Research Viewpoints

Pillar Articles: Stress and Cancer Growth

In the 1950s/1960s, links between stress and tumor growth were found, but molecular pathways were discovered not until the 1970/80s. One publication critically transformed the field of scientific inquiry.

Viewpoint On:

van den Brenk HA, Stone MG, Kelly H, Sharpington C. Lowering of innate resistance of the lungs to the growth of blood-borne cancer cells in states of topical and systemic stress. Br J Cancer. 1976;33(1):60-78. PMID: 175820

The first author

Hendrick (Athos Sydney) van den Brenk was born on 22^nd June 1921 in Sydney, Australia (he died on the 21^st of August 1992). He qualified as Bachelor of Medicine & Bachelor of Surgery in 1944, and he received his Master of Science in 1954. After two years of practice as a general surgeon, he was consultant radiotherapy research officer at the Melbourne Cancer Institute from 1956 to 1967. Then, he was awarded a Fellowship in Cancer research, and he became honorary consultant physician at St Thomas’s Hospital, London, from 1967 to 1978, becoming the Foundation Richard Dimbleby Professor of Cancer Research at St Thomas’s Hospital Medical School from 1975 to 1978. On returning to Australia due to private reasons, he became senior medical officer on the Repatriation Committee from 1979 and senior medical officer of the Commonwealth Department of Veterans’ Affairs. He had an international reputation as a clinical radiotherapist, radiobiologist and experimental oncologist, and he published over 250 papers (1).

The starting point

Until 1976, there existed contrasting results concerning the influence of stress or stressful treatment on tumor growth with either tumor-inhibiting (2,3) or tumor-propagating effects (4-6). However, in all these studies the immune system was not investigated, and these experiments were carried out without a focus on molecular pathways that might inhibit or propagate tumor growth. Form these studies (4-6), van den Brenk and colleagues reasoned “systemic stress indirectly lowers an innate resistance of tissues to growth of cancer cells”. And he further wrote that, presumably, “these results from pharmacologically induced changes in the target tissue which are mediated via neuroendocrinal pathways.”

The discovery

They investigated rats given Walker (W256) tumor cells, prepared in single cell suspension, and injected intravenously. These cells soon colonized the lungs to form metastases. To simulate a stressful situation, they used several different methods: 1) injection of adrenergic drugs, 2) injection of phosphodiesterase inhibitors (that increase effects through cyclic AMP), 3) local x-irradiation of the thorax, 4) convulsive seizures induced by pentylenetetrazole, and 5) restraint stress. Of all stressful interventions, irradiation (moderate effects), injection of isoproterenol (β1/β2-agonist with strong effects), of aminophylline (phosphodiesterase inhibitor with weak effects), of isoproterenol plus aminophylline (strongest effects), induction of convulsive seizures (moderate effects), and restraint stress (moderate effects) increased cancer colony growth in the lungs. The effects of restraint stress-induced increase of tumor colonies were inhibited by adrenalectomy. Furthermore, they recognized that cyclic AMP has a center role in the propagating effects on tumor growth.

In their discussion, they excluded effects through the immune system on obscure theoretical reasons, which might have prevented the ‘Author of this Blog’ to use this particular publication as an important contribution to the field. However, since van den Brenk and colleagues identified the important molecular cAMP-β-adrenergic pathway, which has later been clearly linked to inhibitory immune cell function and increased tumor growth (7-10, and many more), this paper was a trigger to transform this field of scientific inquiry.

Neuroimmunomodulation also published papers on the link between cancer, the immune system, and neuroendocrine modulation (11-16 and more).

References

1. URL: https://livesonline.rcseng.ac.uk/client/en_GB/lives/search/ — enter “E008377” in the search field
2. Rashkis HA. Systemic stress as an inhibitor of experimental tumors in Swiss mice. Science. 1952;116(3007):169-171. PMID: 14950226.
3. Anderson MR. Variations in the rate of induction of chemical carcinogenesis according to differing psychological states in rats. Nature. 1964;204:55-56. PMID: 14240113.
4. Fisher B, Fisher ER. Experimental studies of factors influencing hepatic metastases. III. Effect of surgical trauma with special reference to liver injury. Ann Surg. 1959;150(4):731-744. PMID: 13823186
5. Fisher B, Fisher ER. Experimental studies of factors influencing hepatic metastases. XI. Effect of hepatic trauma in hypophysectomized animals. Proc Soc Exp Biol Med. 1962;109:62-64. PMID: 13893220.
6. Robinson KP, Hoppe E. The development of blood-borne metastases. Effect of local trauma and ischemia. Arch Surg. 1962 Nov; 85:720-4. PMID: 13974455.
7. Stefanski V, Ben-Eliyahu S. Social confrontation and tumor metastasis in rats: defeat and beta-adrenergic mechanisms. Physiol Behav. 1996;60(1):277-282. PMID: 8804676.
8. Shakhar G, Ben-Eliyahu S. In vivo beta-adrenergic stimulation suppresses natural killer activity and compromises resistance to tumor metastasis in rats. J Immunol. 1998;160(7):3251-3258. PMID: 9531281.
9. Hodgson DM, Yirmiya R, Chiappelli F, Taylor AN. Intracerebral interleukin-1beta impairs response to tumor invasion: involvement of adrenal catecholamines. Brain Res. 1999;816(1):200-208. PMID: 9878736.
10. Kalinichenko VV, Mokyr MB, Graf LH Jr, Cohen RL, Chambers DA. Norepinephrine-mediated inhibition of antitumor cytotoxic T lymphocyte generation involves a beta-adrenergic receptor mechanism and decreased TNF-alpha gene expression. J Immunol. 1999;163(5):2492-2499. PMID: 10452985.
11. Blom JM, Tamarkin L, Shiber JR, Nelson RJ. Learned immunosuppression is associated with an increased risk of chemically-induced tumors. Neuroimmunomodulation. 1995;2(2):92-99. PMID: 8521145.
12. Ben-Eliyahu S, Shakhar G, Page GG, Stefanski V, Shakhar K. Suppression of NK cell activity and of resistance to metastasis by stress: a role for adrenal catecholamines and beta-adrenoceptors. Neuroimmunomodulation. 2000;8(3):154-64. PMID: 11124582.
13. Shavit Y, Ben-Eliyahu S, Zeidel A, Beilin B. Effects of fentanyl on natural killer cell activity and on resistance to tumor metastasis in rats. Dose and timing study. Neuroimmunomodulation. 2004;11(4):255-260. PMID: 15249732.
14. ThyagaRajan S, Tran L, Molinaro CA, Gridley DS, Felten DL, Bellinger DL. Prevention of Mammary Tumor Development through Neuroimmunomodulation in the Spleen and Lymph Nodes of Old Female Sprague-Dawley Rats by L-Deprenyl. Neuroimmunomodulation. 2013;20(3):141-151. PMID: 23445569.
15. Alves GJ, Palermo-Neto J. Odor cues released by Ehrlich tumor-bearing mice are aversive and induce psychological stress. Neuroimmunomodulation. 2015;22(3):121-129. PMID: 24714518.
16. Anastassis I, Konsman JP. Causal Histories of Psychological Factors and Cancer: From Psychosomatic Medicine to Neuroimmunomodulation. Neuroimmunomodulation. 2024;31(1):143-156. PMID: 38934151.

(Featured image declaration: modified from brfx from Flickr and macrovector from Flickr)

Pillar Articles: Coping and Immunosuppression

In the 1960s/1970s, it became clear that stress alters immune function (viewpoint of March 28,2024). One publication in 1983 found that controllability or coping of stress is decisive for immunosuppression.

Viewpoint On:

Laudenslager ML, Ryan SM, Drugan RC, Hyson RL, Maier SF. Coping and immunosuppression: inescapable but not escapable shock suppresses lymphocyte proliferation. Science. 1983;221(4610):568-570

The first and senior author

Mark L. Laudenslager (1947 – 2020) received his PhD in 1976 from the University of California, Santa Barbara, followed by a postdoc at the Scripps Institute of Oceanography in San Diego. His first publication in the context of his PhD studies appeared in Nature (1). In 1980, as a postdoctoral trainee, he moved to the Department of Psychiatry, University of Colorado School of Medicine, Denver. Beginning in 1995, he served as Director of the UCHSC-Primate Research Facility for six years. ln the same year, Mark L. Laudenslager was elected as Developmental Psychobiology Research Group (DPRG) Executive Director and continued as a major influence in the DPRG, serving again as Executive Director from 2007-2010. He became a full professor in the same institute in 2008. He received the 2013 Norman Cousins Award from the Psychoneurolmmunology Research Society (PNIRS). In December 2020, he died from a Covid-19 infection.

Steven F. Maier (1943) graduated from the Bronx High School of Science in 1959 and from New York University (NYU) in 1963. He received his PhD in 1968 from the University of Pennsylvania, Philadelphia, and he has been at the University of Colorado at Boulder, since 1973. He received the 2002 Norman Cousins Award from the Psychoneurolmmunology Research Society (PNIRS) and he is winner of the Award for Distinguished Scientific Contributions of the American Psychological Association. Presently, he is Distinguished Professor and Director of the Center for Neuroscience at the University Colorado Boulder.

The starting point

In the year 1967, Seligman and Maier published a seminal paper on the “Failure to escape traumatic shock” (2). The publication deals with escapable and inescapable shock, and it was the platform of a depression model called “learned helplessness.” In the early 1980s, in Colorado, Maier was approached by Laudenslager about collaborating on some studies designed to determine whether and how stress might alter immune function. They hypothesized that immune function was differently influenced by controllability of the stressor.

The discovery

Rats were placed in a small “wheel-turn” box and shock was applied through fixed tail electrodes (3). Each escapable shock ended when the subject turned the wheel in the front of the chamber. Twelve rats were given an average of one escapable shock per minute, for a total of eighty shocks. A second group of twelve rats received inescapable shock. Each was paired with an escapable shock subject; shocks began at the same time as for the escapable shock subject and ended when the latter responded. A third group (N = 8) was restrained in the apparatus for an equivalent period of time but was not shocked (control group). Twenty-four hours later all three groups were given five 5-second, 0.6-mA footshocks in a shuttle box. Blood was then collected. They used a simple immunological test that investigated mitogen-induced proliferation of lymphocytes in vitro (mitogens: Concanavalin A and phytohemagglutinin; proliferation test with [methyl-3H]thymidine) (3). They wrote:

Neither exposure to escapable shock nor restraint stress affected lymphocyte proliferation. However, inescapable shock was associated with suppression of lymphocyte proliferation. Thus, a single session of eighty brief shocks moderate intensity can substantially inhibit lymphocyte proliferation in vitro if the subject has no control over the shocks. However, identical shocks produce no decrease in proliferation if the subject can escape them. Thus, the ability to exert control over the stressor completely prevented immunosuppression.

Criticism

Although a first seminal paper like the one of Mark L. Laudenslager et al. can stimulate a whole research field, it can also induce a lot of criticism because other authors find different things. The first group of authors that publicly criticized the work were the authors themselves (4). From my point of view, this is a respectable sign of good scientific behavior. They discussed that the results were highly variable depending on many individual parameters. They also recognized that the immune parameter, whether lymphocyte proliferation or antigen-induced antibody production, can influence the direction of the results (4). Nevertheless, immunosuppression after inescapable shock was confirmed by several studies of other authors (5-9, and several more), but these studies also demonstrated the variable influences of the environment. While in the 1980s, most researchers in the field of PsychoNeuroImmunology thought that stress – particularly strong stress – inhibits immune functions, this picture has changed to the opposite direction during the 1990s (10-12), later summarized in a seminal review (13). From this point of view, stress can have immunosuppressive (when strong and long-standing) but also immunoactivating functions (when acute).

Neuroimmunomodulation also published a paper of the senior author (14). This time, inescapable shock helped to resolve bacteria-induced skin inflammation significantly faster in challenged than in non-stressed rats (14). This latter publication corresponded to the general picture of the late 1990s.

References

1. Carlisle HJ, Laudenslager ML. Inhibition of airlicking in thirsty rats by cooling the preoptic area. Nature. 1975;255(5503):72-73
2. Seligman ME, Maier SF. Failure to escape traumatic shock. J Exp Psychol. 1967;74:1-9
3. Laudenslager ML, Ryan SM, Drugan RC, Hyson RL, Maier SF. Coping and immunosuppression: inescapable but not escapable shock suppresses lymphocyte proliferation. Science. 1983;221(4610):568-570
4. Maier SF, Laudenslager ML. Inescapable shock, shock controllability, and mitogen stimulated lymphocyte proliferation. Brain Behav Immun. 1988;2:87-91
5. Bukilica M, Djordjević S, Marić I, Dimitrijević M, Marković BM, Janković BD. Stress-induced suppression of experimental allergic encephalomyelitis in the rat. Int J Neurosci. 1991;59:167-175
6. Zalcman S, Richter M, Anisman H. Alterations of immune functioning following exposure to stressor-related cues. Brain Behav Immun. 1989;3:99-109
7. Sandi C, Borrell J, Guaza C. Behavioral factors in stress-induced immunomodulation. Behav Brain Res. 1992;48:95-98
8. Fleshner M, Watkins LR, Lockwood LL, Bellgrau D, Laudenslager ML, Maier SF. Specific changes in lymphocyte subpopulations: a potential mechanism for stress-induced immunomodulation. J Neuroimmunol. 1992;41:131-142
9. Kusnecov AW, Rabin BS. Inescapable footshock exposure differentially alters antigen- and mitogen-stimulated spleen cell proliferation in rats. J Neuroimmunol. 1993;44:33-42
10. Dhabhar FS, McEwen BS. Stress-induced enhancement of antigen-specific cell-mediated immunity. J Immunol. 1996;156:2608-2615
11. Dhabhar FS, McEwen BS. Acute stress enhances while chronic stress suppresses cell-mediated immunity in vivo: a potential role for leukocyte trafficking. Brain Behav Immun. 1997;11:286-306
12. Dhabhar FS, McEwen BS. Enhancing versus suppressive effects of stress hormones on skin immune function. Proc Natl Acad Sci U S A. 1999;96:1059-1064
13. Dhabhar FS. The short-term stress response – Mother nature’s mechanism for enhancing protection and performance under conditions of threat, challenge, and opportunity. Front Neuroendocrinol. 2018;49:175-192
14. Deak T, Nguyen KT, Fleshner M, Watkins LR, Maier SF. Acute stress may facilitate recovery from a subcutaneous bacterial challenge. Neuroimmunomodulation. 1999;6:344-354

(Featured image declaration: Modified from Bennett from Flickr and NIAID from Flickr and Flickr)

Pillar Articles: Sympathetic Nerve Fibers in a Lymphoid Organ – The Spleen

The brain uses efferent sympathetic nerve fibers with its neurotransmitter noradrenaline to make contact with immune cells in peripheral lymphoid organs like the spleen. Who discovered it?

Viewpoint On:

von Euler US. A specific sympathomimetic ergone in adrenergic nerve fibres (sympathin) and its relations to adrenaline and nor-adrenaline. Acta Physiol Scand 1946;12:73-97

von Euler US. A substance with sympathin E properties in spleen extracts. Nature 1946;157:369

The idea

Already in the mid-19^th century, the Swiss professor of anatomy, Albert von Kölliker, described the innervation of the spleen as nerve fibers accompanying blood vessels. He mentioned that nerve fibers of ox and sheep are huge, similarly in size like the splenic artery (1). Kölliker also recognized that these nerve fibers were unmyelinated – called Remak fibers according to Robert Remak (1815-1865) who found them elsewhere. However, the subtype of the nervous system – whether sympathetic or parasympathetic – was not known.

Different involuntary autonomic nerve fiber types were already known in the early 20^th century when John Newport Langely, in 1921, distinguished the sympathetic, from the parasympathetic, and from the enteric nervous system (2). However, the individual neurotransmitters of the different nerve fiber types were not found. Different groups discovered adrenaline in the adrenal glands at the transition from the 19th to the 20^th century (3-5), and adrenaline was discussed to be the first hormone isolated (6).

In studying the sympathomimetic properties of stimulation of sympathetic nerve fibers Cannon and Bacq, initially, thought that adrenaline is released from the sympathetic nerve fibers (7). However, further studies of Cannon and Rosenbluth showed that stimulation of sympathetic nerves elicited remote actions, which were different from adrenaline effects (8). This prompted several groups to study the real neurotransmitters of sympathetic nerve fibers.

The discovery

The Swede Ulf S. von Euler (1905-1983, Nobel Prize in 1970) started his work in the Karolinska Institute, Stockholm, Sweden. In his thesis, he worked on vasoconstriction, and at the beginning of the 1930s, he thrived in the laboratory of Sir Henry Dale, London. Returning to Stockholm, he was appointed full professor in 1939 at the Karolinska Institute. He worked on prostaglandins and angiotensin before he began to study neurotransmitters of the sympathetic nervous system. From the start, he recognized that the spleen is an ideal organ because it contained high amounts of a pressor substance (vasoconstriction). In his seminal papers of the year 1946 (9, 10), he described noradrenaline in splenic extracts (9) and in sympathetic nerves of the spleen (10). Noradrenaline was identified by a multitude of biological tests that were standard at the time of von Euler. He also recognized that cutting the sympathetic nerve fibers to the spleen leads to a clear reduction of the sympathomimetic pressor substance in the spleen (10). In many further studies, von Euler refined his early work (e.g. 11, 12).

Illustration showing the contact between a spleen cell and the sympathetic nerve ending. Schematics were created by the blogger.

Discussion

Between the 1940s and mid-1960s, scientists thought that sympathetic regulation in the spleen serves solely vasoregulation and perhaps storage of red blood cells – and nothing else. The term sympathetic neuroimmunomodulation was not born. This changed with the work of several groups in the late 1960s (13). This was corroborated by new staining techniques of sympathetic nerve fibers (14-17). After the discovery of the key enzyme of catecholamine production – the tyrosine hydroxylase (18) – specific staining of sympathetic nerve fibers became possible. Both techniques – chemical and immunological – together with the understanding of a crosstalk between immune cells and sympathetic nerve fibers (13) led to clear evidence of anatomical contact sites between nerve fibers and immune cells in lymphoid organs studied by David Felten and his group (summarized in 19, and some more publications).

Sympathetic neuroimmune interactions stood the test of time, and Neuroimmunomodulation published some relevant experiments (20 – 24, and many more).

References

1. von Kölliker A. Handbuch der Gewebelehre des Menschen für Aerzte und Studirende. Verlag W.Engelmann, Leipzig, 1852, p. 445
2. Langely JN. The autonomic nervous system. Cambridge: W. Heffer and Sons, Ltd; 1921
3. Oliver G, Schäfer EA. The physiological effects of extracts of the suprarenal capsules. J Physiol. 1895;18(3):230–276.
4. Abel J. On epinephrine, the active constituent of the suprarenal capsule and its compounds. Proc Am Physiol Soc. 1898(3–4):3–5.
5. Takamine J. Adrenalin, the active principle of the suprarenal glands, and its mode of preparation. Am J Pharm. 1901;73:523–31.
6. Rao Y. The first hormone: adrenaline. Trends Endocrinol Metab. 2019;30:331–334.
7. Cannon WB, Bacq ZM Studies on the conditions of activity in endocrine organs A Hormone Produced by Sympathetic Action on Smooth Muscle. Am J Physiol 1931;96: 392-412
8. Cannon WB, Rosenbluth A. A comparison of the effects of sympathin and adrenine on the iris. Am J Physiol 1935;113:251-258
9. von Euler US. A substance with sympathin E properties in spleen extracts. 1946;157:369
10. von Euler US. A specific sympathomimetic ergone in adrenergic nerve fibres (sympathin) and its relations to adrenaline and nor-adrenaline. Acta Physiol Scand 1946;12:73-97
11. von Euler US, Stjärne L. Studies on the release of the adrenergic neurotransmitter in the perfused ox spleen. II. Effects of various membrane active substances. Acta Physiol Scand Suppl. 1955;33(118):70-74
12. von Euler US, Hillarp NA. Evidence for the presence of noradrenaline in submicroscopic structures of adrenergic axons. Nature 1956;177:44-45
13. demonstrated in the Viewpoint of July 24, 2024: https://researchviewpoints.karger.com/on-research/pillar-articles-adrenergic-modulation-of-leukocytes-anni-mirabiles-1968-to-1970/
14. Falck B, Torp A. A fluorescence method for histochemical demonstration of noradrenalin in the adrenal medulla. Med Exp Int J Exp Med. 1961;5(6):429–432.
15. Dahlstroem AB, Zetterstroem BE. Noradrenaline stores in nerve terminals of the spleen: changes during hemorrhagic shock. Science. 1965;147(3665):1583–1585.
16. Gillespie JS, Kirpekar SM. The histological localization of noradrenaline in the cat spleen. J Physiol 1966;187:69-79
17. Hamberger B, Malmfors T, Stjärne L. Noradrenaline uptake and fluorescence histochemistry in bovine splenic nerves. Acta Physiol Scand. 1971;82(1):107–114.
18. Nagatsu T, Levitt M, Udenfriend S. Tyrosine hydroxylase. J Biol Chem. 1964;239(9):2910–2917.
19. Felten DL, Felten SY, Bellinger DL, Carlson SL, Ackerman KD, Madden KS, et al. Noradrenergic sympathetic neural interactions with the immune system: structure and function. Immunol Rev. 1987;100:225–260
20. Genaro AM, Cremaschi GA, Gorelik G, Sterin-Borda L, Borda ES. Downregulation of beta adrenergic receptor expression on B cells by activation of early signals in alloantigen-induced immune response. Neuroimmunomodulation. 2000;8:114-21
21. Page GG, Ben-Eliyahu S. Natural killer cell activity and resistance to tumor metastasis in prepubescent rats: deficient baselines, but invulnerability to stress and beta-adrenergic stimulation. Neuroimmunomodulation. 2000;7:160-168
22. Oberbeck R, Schmitz D, Wilsenack K, Schüler M, Pehle B, Schedlowski M, Exton MS. Adrenergic modulation of survival and cellular immune functions during polymicrobial sepsis. Neuroimmunomodulation. 2004;11:214-223
23. Kitamura H, Shiva D, Woods JA, Yano H. Beta-adrenergic receptor blockade attenuates the exercise-induced suppression of TNF-alpha in response to lipopolysaccharide in rats. Neuroimmunomodulation. 2007;14:91-96
24. Straub RH, Dufner B, Rauch L. Proinflammatory α-Adrenergic Neuronal Regulation of Splenic IFN-γ, IL-6, and TGF-β of Mice from Day 15 onwards in Arthritis. Neuroimmunomodulation. 2020;27:58-68

(Featured image declaration: Obtained from”Overview of splenic innervation of a C57BL/6 mouse” from Hu, D., Al-Shalan, H.A.M., Shi, Z. et al. Distribution of nerve fibers and nerve-immune cell association in mouse spleen revealed by immunofluorescent staining. Sci Rep 10, 9850 (2020). https://doi.org/10.1038/s41598-020-66619-0, CC BY 4.0 license )

Pillar Articles: Sex Hormones Influence the Immune System

Viewpoint On:

Laqueur E, Hart PC, de Jongh SE. Ueber weibliches Sexualhormon (Menformon), das Hormon des östrischen Zyklus III. Dtsch Med Wochenschr. 1926;30:1247-1250

Korenchevsky V, Dennison M, Schalit R. CLVI. The response of castrated male rats to the injection of testicular hormone. Biochem J. 1932;26:1306-1314

The idea

The two author groups of The Netherlands (Laqueur et al., Amsterdam, pharmacotherapeutic laboratory of the university) and England (Korenchevsky et al., London, Lister Institute) were interested in methods of testing the activity and strength of estrogenic (1) and testicular hormones (2). At the time, without knowing the exact nature of the tested hormones, biological test methods were very common. Biological test methods allowed for isolation of increasingly pure test substances, which finally led to the description of the authentic sex hormones and their exact molecular structure (3-4).

The discovery

In a multitude of investigations, the two author groups recognized that the hormone preparations significantly influenced the thymus – the location of naïve T lymphocytes, as we know it today. Indeed, the hormonal preparations, whether estrogenic or testicular, lead to thymus involution / shrinkage. The authors did not know the exact function of the thymus, but they clearly showed the first influence of sex hormones on a lymphoid organ. Later, it was also recognized that estrogens/testosterone has a strong influence on the B lymphocyte equivalent of the thymus, where naïve B lymphocytes are produced, the Bursa Fabricius of birds (5).

Discussion

Many groups have supported the concept of thymus involution with the appearance of gonadal hormones, also in humans. Before, and during the process of puberty, the thymus markedly shrinks. Real readout parameters of the immune system appeared later in the history of immunology in the form of antigen-specific antibodies, and it was demonstrated that the antibody response is sex-dependent, and that orchiectomy increased the specific antibody response (6). The later information speaks for the immunoinhibitory role of testosterone.

Thymus involution remains an enigma in immunology, but we know that it happens in all vertebrates and, thus, it is likely an evolutionary conserved program. From an evolutionary standpoint, strong early thymus activity allows for a diverse T cell repertoire to fight infections, particularly in the young. During the early years, a fixed T cell repertoire is established which serves the immune system for most of the available infections in a given local environment. Since the maintenance of thymus function is energy consuming, some believe that shrinkage of the thymus is necessary to devote energy to other physiological processes (7). In addition, the force of natural selection declines with age. Until maturity and reproduction, this force of natural selection is strongest but, thereafter, it shrinks, and involution of the thymus just happened independent of selection.

Since many autoimmune disease are more prevalent in women than men, the immunostimulatory nature of estrogens (mainly on B lymphocytes) and the immunoinhibitory influence of androgens was often reviewed in the context of autoimmune diseases (8-11).

Sex hormone regulation of immune reactions stood the test of time, and Neuroimmunomodulation published some relevant experiments (12-16, and many more).

References

1. Laqueur E, Hart PC, de Jongh SE. Ueber weibliches Sexualhormon (Menformon), das Hormon des östrischen Zyklus III. Dtsch Med Wochenschr. 1926;30:1247-1250
2. Korenchevsky V, Dennison M, Schalit R. CLVI. The response of castrated male rats to the injection of testicular hormone. Biochem J. 1932;26:1306-1314
3. David K, Dingemanse E, Freud J, Laqueur E. Über krystallinisches männliches Hormon aus Hoden (Testosteron), wirksamer als aus Harn oder aus Cholesterin bereitetes Androsteron. Biol Chem. 1935;233:281–283
4. Butenandt A, Hanisch G. Über Testosteron. Umwandlung des Dehydroandrosterons in Androstendiol und Testosteron; ein Weg zur Darstellung des Testosterons aus Cholesterin. Biol Chem. 1935;237:89–97
5. Selye H. Morphological changes in the fowl following chronic overdosage with various steroids. J Morphol 1943;73:401-421
6. Batchelor JR, Chapman BA. The influence of sex upon the antibody response to an incompatible tumour. Immunology 1965;9:553-564
7. Shanley DP, Aw D, Manley NR, Palmer DB. An evolutionary perspective on the mechanisms of immunosenescence. Trends Immunol. 2009;30:374-381
8. Cohn DA. High sensitivity to androgens as a contributing factor in sex differences in the immune Response. Arthritis Rheum 1979;22:1218-1233
9. Ansar Ahmed S, Penhale WJ, Talal N. Sex hormones, immune responses, and autoimmune diseases. Mechanisms of sex hormone action. Am J Pathol. 1985;121:531-551
10. Cutolo M, Sulli A, Seriolo B, Accardo S, Masi AT. Estrogens, the immune response and autoimmunity. Clin Exp Rheumatol 1995;13:217-226
11. Cutolo M, Straub RH. Sex steroids and autoimmune rheumatic diseases: state of the art. Nat Rev Rheumatol. 2020;16:628-644
12. Suescun M, Chisari AN, Carino M, Hadid R, Gaillard RC, Spinedi E. Sex steroid regulation of the hypothalamo-pituitary-adrenal axis activity in middle-aged mice during endotoxic shock. Neuroimmunomodulation. 1994;1:315-320
13. Di Santo E, Foddi MC, Ricciardi-Castagnoli P, Mennini T, Ghezzi P. DHEAS inhibits TNF production in monocytes, astrocytes and microglial cells. 1996;3:285-288
14. Shelat SG, Aird F, Redei E. Exposure to dehydroepiandrosterone in utero affects T-cell function in males only. Neuroimmunomodulation. 1997;4:154-162
15. Nanamiya W, Takao T, Asaba K, De Souza EB, Hashimoto K. Effect of orchidectomy on the age-related modulation of IL-1beta and IL-1 receptors following lipopolysaccharide treatment in the mouse. Neuroimmunomodulation. 2000;8:13-19
16. Macció DR, Calfa G, Roth GA. Oral testosterone in male rats and the development of experimental autoimmune encephalomyelitis. Neuroimmunomodulation. 2005;12:246-254

(Featured image declaration: Modified from brgfx on freepik and NEUROtiker on Wikipedia)

Pillar Articles: Brain Lesions Influence the Immune Response

Viewpoint On:

Janković BD, Isaković K. Neuro-endocrine correlates of immune response. I. Effects of brain lesions on antibody production, Arthus reactivity and delayed hypersensitivity in the rat. Int Arch Allergy Appl Immunol. 1973;45:360-372

Branislav D. Janković (1920-1994) studied Medicine at the Belgrade University School of Medicine and graduated in 1947 (ref. 1). He then went on to pursue Ph.D. training in Immunology which he finished in 1954. In 1964, he became full professor of Microbiology and Immunology. Between, 1954 to 1985, he was director of the Institute of Microbiology and Immunology at the School of Pharmacy in Belgrade. During this time, he founded two other research centers in former Yugoslavia: in 1965, the International Laboratory for Brain Research (Dobrota, Montenegro); in 1969, the lmmunology Research Center (Belgrade, Serbia). He was co-founder of the European Federation of Immunological Societies (EFIS) in 1975 and of the International Society for Neuroimmunomodulation (ISNIM) in 1986. In 1991, he became President of the Science Society of Serbia (ref. 1).

Katarina Isaković was born in Lalić in 1926 (ref. 2). She graduated from the Belgrade University School of Medicine in 1953 and defended her PhD thesis in the field of immunology in 1962. In 1956, she entered the Institute of Microbiology and Immunology, where she remained until her retirement in 1992. She became full professor in 1977. She contributed to the foundation and development of the lmmunology Research Center (Belgrade, Serbia), and she was Director of the Center between 1985-1990. The period between 1963 and 1964 she spent at Yale University, USA, and she also spent some time in Belgium, Switzerland and Finland. She is a member of the Serbian Scientific Society and Society of Yugoslav Immunologists (one of its founders) (ref. 2).

The idea

The authors wished to study possible links between the brain and the immune system in the sense of neuroimmunomodulation (3). For these studies, they lesioned certain areas in the brain and, afterwards, checked the humoral and cellular immune response to an immunization with bovine serum albumin (BSA).

The discovery

In order to check for possible connections, they lesioned different areas in the brain by means of electrolytic defects applied through stainless steel electrodes. Lesions were directed towards the following structures (postmortem identification): hypothalamus, reticular formation, thalamus, superior colliculus, caudate nucleus, and amygdala. They included a large number of verum and control animals. Immunization with BSA was performed 24 hours after brain lesioning, and skin hypersensitivity and anti-BSA-antibody response were tested 10, 20, and 30 days after immunization. Lesioning of the hypothalamus and the reticular formation led to clear reductions in skin hypersensitivity and anti-BSA-antibody response. In the discussion to this paper (3), the authors demonstrated – in figures 5 to 8 – very nice explanations how the brain might interfere with the immune system through endocrine and neuronal pathways. The mentioned speculative pathways in figures 5-8 have been confirmed in later decades.

E.g., original figure 5 of reference 3 (copyrights by Karger, Basel, Switzerland):

Neuro-Endocrine System and Immune Response

Fig. 5. Scheme of the relationship between the lymphatic cells, and the anterior hypothalamus, adenohypophysis, adrenals and gonades.

The publication of Janković and Isaković was supported by their own work from the same year (4), where the two authors demonstrated morphological changes in lymphatic organs upon electrolytic brain lesions.

The central nervous system regulation of immune reactions stood the test of time, and Neuroimmunomodulation published some relevant experiments with brain lesions (5-9).

References

1. Marković BM, Dimitrijević M, Radulovic J, Laban O. In Memoriam – Branislav. D. Janković (1920-1994). Brain Behav Immun 1994;8:279-281
2. From: https://nds.edu.rs/clanovi/prof-dr-katarina-z-isakovic/?lang=lat
3. Janković BD, Isaković K. Neuro-endocrine correlates of immune response. I. Effects of brain lesions on antibody production, Arthus reactivity and delayed hypersensitivity in the rat. Int Arch Allergy Appl Immunol. 1973;45:360-372
4. Isaković K, Janković BD. Neuro-endocrine correlates of immune response. II. Changes in the lymphatic organs of brain-lesioned rats. Int Arch Allergy Appl Immunol. 1973;45:373-384
5. Gushchin GV, Jakovleva EE, Kataeva GV, Korneva EA, Gajewski M, Grabczewska E, Laskowska-Bozek H, Maslinski W, Ryzewski J. Muscarinic cholinergic receptors of rat lymphocytes: effect of antigen stimulation and local brain lesion. Neuroimmunomodulation 1994;1:259-264
6. Tsuboi H, Miyazawa H, Wenner M, Iimori H, Kawamura N. Lesions in lateral hypothalamic areas increase splenocyte apoptosis. Neuroimmunomodulation 2001;9:1-5
7. Irie M, Nagata S, Endo Y. Anterior hypothalamic lesions inhibit antigen-induced airway eosinophilia in rats. Neuroimmunomodulation. 2002-2003;10:305-309
8. Hahm ET, Lee JJ, Lee WK, Bae HS, Min BI, Cho YW. Electroacupuncture enhancement of natural killer cell activity suppressed by anterior hypothalamic lesions in rats. Neuroimmunomodulation. 2004;11:268-272
9. Dutta G, Mondal N, Goswami A, Majumdar D, Ghosh T. Effects of electrolytic lesion of medial septum on some immune responses in rats. Neuroimmunomodulation 2011;18:232-239

(Featured image declaration: Modified from kjpargeter on Freepik and NIAID on Flickr)

Pillar Articles: The Sympathetic Nervous System Influences the Primary Immune Response

Viewpoint On:

Besedovsky HO, del Rey A, Sorkin E, Da Prada M, Keller HH. Immunoregulation mediated by the sympathetic nervous system. Cell Immunol. 1979;48(2):346-355

del Rey A, Besedovsky HO, Sorkin E, da Prada M, Arrenbrecht S. Immunoregulation mediated by the sympathetic nervous system, II. Cell Immunol. 1981;63(2):329-334

Adriana del Rey (1950) is an Argentinian-German from Rosario who was educated in Argentina and studied Biology there. From 1975 to 1976, she was research assistant in the Institute of Immunology of the Medical Faculty of the University of Rosario. In 1977, she moved to Switzerland, Davos, to become scientist in the Department of Medicine in the Swiss Research Institute in Davos, where she stayed until 1988. From 1989-1992, she became senior scientist in the Division of Neurobiology in the Department of Research of the Basel Cantonal Hospital, Switzerland. In 1992, she moved to Marburg, Department of Immunophysiology at the University of Marburg, Germany, where she still works and lives.

The curriculum vitae of Hugo Oscar Besedovsky (1939) and Ernst Sorkin (1920 – 2009) have been described in the blog of January 28, 2025, with the title “The Primary Immune Response Changes the Body’s Own Hormones”.

The idea

As described in the preceding blog of January 28, 2025, the authors found a clear response of the hypothalamic-pituitary adrenal (HPA) axis consequently to an antigenic stimulus. They discussed the possibility of a feedback regulation of the HPA axis on the immune system (1). With this information in their hands, Adriana del Rey and her coauthors wanted to investigate the second most important efferent system that connects the brain to the periphery. They hypothesized that the sympathetic nervous system (SNS) directly influences the immune response to a foreign antigen, and – vice versa – that the immune response influences the SNS.

The discovery

In their first publication of 1979, they recognized that surgical and chemical removal of the sympathetic nervous system increased the stimulated immune response in the spleen (plaque forming cell response as an indication of IgM antibody production). In other words, the SNS had a clear inhibitory influence on IgM antibody formation (2). In their hands, an α2-adrenergic agonist – clonidine – dose-dependently inhibited the stimulated antibody response in vitro using spleen cells (2). Other authors, who corroborated the α2-adrenergic inhibition of the primary antibody response, later studied the time dependency of the sympathetic influence on the antibody response (3).

Vice versa, during the immune response during 8 consecutive days, the IgM antibody response started to rise strongly on day 3 to reach a maximum on day 4 and then turned down to zero on day 8 (2), which is typical for the IgM antibody response to a foreign antigen. During the same period of 8 days, the amount of noradrenaline – the sympathetic neurotransmitter from splenic nerve fibers – went down from 100% at the beginning to 25% on day 3 and 30% on day 4 to reach the starting level of 100% between day 6 and 8 (2). These data clearly demonstrated the reciprocal influence of activated immune cells on noradrenaline content in the spleen. The reduction of noradrenaline in the spleen must be viewed as an increased loss of the neurotransmitter relative to the local production in the nerve ending after a period of stimulated SNS activity.

This paper (2) and two follow-up papers (4,5) clearly demonstrated the mutual interaction of splenic immune cells and sympathetic nerve fibers / neurotransmitters. In further studies, the authors demonstrated that the duration of the decrease in splenic noradrenaline depends on the intensity of the immune response (5). Other groups – a little later – supported the same sympathetic neuroimmunomodulation (6,7).

Adriana del Rey and her coworkers wrote (4): “The decrease in catecholamine levels induced by immune responses is therefore likely to reflect the existence of sympathetic immunoregulatory circuits. What one likes to know now is the nature of the links between the immune system and the sympathetic nervous system and how sympathetic signals are coordinated with autoregulatory immunologic circuits.”

The sympathetic regulation of splenic immune reactions stood the test of time, and Neuroimmunomodulation published some relevant experiments (8-12).

References

1. Besedovsky H, Sorkin E, Keller M, Müller J. Changes in blood hormone levels during the immune response. Proc Soc Exp Biol Med. 1975;150:466-470
2. Besedovsky HO, del Rey A, Sorkin E, Da Prada M, Keller HH. Immunoregulation mediated by the sympathetic nervous system. Cell Immunol. 1979;48:346-355
3. Sanders VM, Munson AE. Role of alpha adrenoceptor activation in modulating the murine primary antibody response in vitro. J Pharmacol Exp Ther. 1985;232:395-400
4. del Rey A, Besedovsky HO, Sorkin E, da Prada M, Arrenbrecht S. Immunoregulation mediated by the sympathetic nervous system, II. Cell Immunol. 1981;63(2):329-334
5. del Rey A, Besedovsky HO, Sorkin E, Da Prada M, Bondiolotti GP. Sympathetic immunoregulation: difference between high- and low-responder animals. Am J Physiol. 1982;242:R30-R33
6. Williams JM, Peterson RG, Shea PA, Schmedtje JF, Bauer DC, Felten DL. Sympathetic innervation of murine thymus and spleen: evidence for a functional link between the nervous and immune systems. Brain Res Bull. 1981;6:83-94
7. Miles K, Quintáns J, Chelmicka-Schorr E, Arnason BG. The sympathetic nervous system modulates antibody response to thymus-independent antigens. J Neuroimmunol. 1981;1:101-105
8. Esquifino AI, Cardinali DP. Local regulation of the immune response by the autonomic nervous system. Neuroimmunomodulation. 1994;1:265-273
9. Leo NA, Callahan TA, Bonneau RH. Peripheral sympathetic denervation alters both the primary and memory cellular immune responses to herpes simplex virus infection. Neuroimmunomodulation. 1998;5:22-35
10. Hori T, Katafuchi T, Take S, Shimizu N. Neuroimmunomodulatory actions of hypothalamic interferon-alpha. Neuroimmunomodulation. 1998;5:172-177
11. Molina PE. Noradrenergic inhibition of TNF upregulation in hemorrhagic shock. Neuroimmunomodulation. 2001;9:125-133
12. Straub RH, Dufner B, Rauch L. Proinflammatory α-Adrenergic Neuronal Regulation of Splenic IFN‑g, IL-6, and TGF-β of Mice from Day 15 onwards in Arthritis. Neuroimmunomodulation. 2020;27:58-68

(Featured image declaration: created by Rainer H. Straub)

Pillar Articles: The Primary Immune Response Changes the Body’s Own Hormones

Viewpoint On:

Besedovsky H, Sorkin E, Keller M, Müller J. Changes in blood hormone levels during the immune response. Proc Soc Exp Biol Med. 1975;150:466-470. doi: 10.3181/00379727-150-39057. PMID: 1208563.

Hugo Oscar Besedovsky (26.10.1939 – ) is a contemporary Argentinian-German from Rosario with Russian roots who was educated in Argentina, studied medicine in Argentina and became physiologist and pediatrician in Argentina in the 1960s. Due to his interest in Science and challenging times in Argentina (anti-democratic military government), he moved to Switzerland, in the early 1970s to become a senior scientist in the Department of Medicine in the Swiss Research Institute in Davos. This special Research Institute has a very lively history, as it started with tuberculosis research in 1905, was a physical-meteorological observatory, a research institute for high altitude climate, and became – from 1962 to 1985 – an Institute of Neuroendocrine-Immune Interactions under Ernst Sorkin. Hugo Besedovsky was its Director between 1986 and 1987 (after Sorkin’s retirement). In 1988, the name of the institute was changed into Swiss Institute of Allergy and Asthma Research, a subject that is still the focus today (see: https://www.siaf.uzh.ch/index.html). In 1989 to 1991, Besedovsky became Head of the research group in the Division of Neurobiology in the Department of Research of the Cantonal Hospital Basel, Switzerland. In 1991, he became full professor of Human Physiology at the University of Marburg, Germany, where he still lives and works with his wife Adriana del Rey (see Blog 12). The couple has two daughters.

Ernst Sorkin (1920 – 2009) was born in Basel, Switzerland. He received his Ph.D. in 1946 from the University of Basel, became professor in the same town in 1952 and then moved to Copenhagen as a researcher in the World Health Organization from 1953-1961. Then, he was offered the Director position of the Swiss Research Institute, Davos, in 1961, and he hold this position until 1985 – until retirement. He was also President of the Swiss Society of Immunology and Consultant at the Basel Institute of Immunology. He died in 2009.

The discovery

In their publication (1), the authors wrote:

“Investigations on the involvement of hormones in the immune response have generally involved the parenteral administration of hormones to experimental animals and man … these experiments demonstrate that changes in the level of various hormones can considerably influence immune performance. … However, to the best of our knowledge the possibility that the immune response would itself bring about changes in hormone levels has not been previously considered.”

Indeed, this was the seminal idea of Besedovsky et al. because they were interested in the physiological effects of a primary immune reaction by looking on the hormonal response. They injected different types of antigens into rats (sheep red blood cells, trinitrophenyl – hemocyanin [TNP]) and mice (TNP-horse erythrocytes) and observed the course of serum corticosterone and serum thyroxine after injection for several days. Parallel to the increase of the stimulated immune response (plaque forming cell response as an indication of antibody production between day 3-8), serum levels of corticosterone rose at day 3-10 by a factor of 3 to 5, and thyroxine levels fall by 20-30% in the same observation period. The data presented in Figure 1 of this publication (1) are impressively clear. The authors wrote:

“The present work has far greater implications in that it makes evident that the immune response itself affects hormonal levels in the blood. The corticosterone levels attained at the peak of the immune response in rats were of the same magnitude as the concentrations observed in blood of stressed or ACTH-treated mice which inhibited the capacity of spleen in vitro to respond to sheep red blood cells with plaque formation.”

And further down: “The present studies show that during the immune response hormonal changes occur that could regulate at least in part by a feedback mechanism the duration and possibly even the magnitude of the immune response.”

For the first time, the authors recognized the possibility of a feedback regulation of the endogenous hormonal apparatus on the immune response, which had been subject of further studies of Besedovsky et al. (2-7, and some more). One of these studies directly investigated the hypothalamic electrical response measured at neurons in the ventromedial hypothalamus (3), which demonstrated the involvement of other important parts of the hypothalamic-pituitary-adrenal axis.

The hormonal response to primary immune reactions stood the test of time and some relevant experiments have also been published in Neuroimmunomodulation (8-15, and several more).

References

1. Besedovsky H, Sorkin E, Keller M, Müller J. Changes in blood hormone levels during the immune response. Proc Soc Exp Biol Med. 1975;150:466-470
2. Besedovsky H, Sorkin E. Network of immune-neuroendocrine interactions. Clin Exp Immunol. 1977;27:1-12
3. Besedovsky H, Sorkin E, Felix D, Haas H. Hypothalamic changes during the immune response. Eur J Immunol. 1977;7:323-325
4. Besedovsky HO, Sorkin E, Keller M. Changes in the concentration of corticosterone in the blood during skin-graft rejection in the rat. J Endocrinol. 1978;76:175-176
5. Besedovsky HO, Del Rey A, Sorkin E. Antigenic competition between horse and sheep red blood cells as a hormone-dependent phenomenon. Clin Exp Immunol. 1979;37:106-113
6. Besedovsky HO, del Rey AE, Sorkin E. Immune-neuroendocrine interactions. J Immunol. 1985;135(2 Suppl):750s-754s
7. Besedovsky H, del Rey A, Sorkin E, Dinarello CA. Immunoregulatory feedback between interleukin-1 and glucocorticoid hormones. Science. 1986;233:652-654
8. Schotanus K, Makara GB, Tilders FJ, Berkenbosch F. ACTH response to a low dose but not a high dose of bacterial endotoxin in rats is completely mediated by corticotropin-releasing hormone. Neuroimmunomodulation. 1994;1:300-307
9. Suescun M, Chisari AN, Carino M, Hadid R, Gaillard RC, Spinedi E. Sex steroid regulation of the hypothalamo-pituitary-adrenal axis activity in middle-aged mice during endotoxic shock. Neuroimmunomodulation. 1994;1:315-320
10. Hadid R, Spinedi E, Giovambattista A, Chautard T, Gaillard RC. Decreased hypothalamo-pituitary-adrenal axis response to neuroendocrine challenge under repeated endotoxemia. Neuroimmunomodulation. 1996;3:62-68
11. Savino W, Arzt E, Dardenne M. Immunoneuroendocrine connectivity: the paradigm of the thymus-hypothalamus/pituitary axis. Neuroimmunomodulation. 1999;6:126-136
12. Ando T, Dunn AJ. Mouse tumor necrosis factor-alpha increases brain tryptophan concentrations and norepinephrine metabolism while activating the HPA axis in mice. Neuroimmunomodulation. 1999;6:319-329
13. Hadid R, Spinedi E, Chautard T, Giacomini M, Gaillard RC. Role of several mediators of inflammation on the mouse hypothalamo-pituitary-adrenal axis response during acute endotoxemia. Neuroimmunomodulation. 1999;6:336-343
14. Kusnecov AW, Rossi-George A. Potentiation of interleukin-1beta adjuvant effects on the humoral immune response to antigen in adrenalectomized mice. Neuroimmunomodulation. 2001;9:109-118
15. Nicolaides NC, Kyratzi E, Lamprokostopoulou A, Chrousos GP, Charmandari E. Stress, the stress system and the role of glucocorticoids. Neuroimmunomodulation. 2015;22:6-19

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Pillar Articles: Leukocytes Produce Hormones

Viewpoint On:

Smith EM, Blalock JE. Human leukocyte production of corticotropin and endorphin-like substances: Association with leukocyte interferon. Proc. Natl. Acad. Sci. USA 1981;78:7530-7534

J. Edwin Blalock received his B.S. and Ph.D. degrees in 1971 and 1976 from the University of Florida. After one-year postdoctoral training at the University of Texas Medical Branch, Galveston, he joined the faculty in 1977 and earned the title of Professor of Microbiology in 1984. Dr. Blalock joined the University of Alabama at Birmingham (UAB) faculty in 1986 as Professor of Physiology and Biophysics. Then, he entered the UAB Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine in 2009. Blalock is internationally recognized for his research in neuroimmunology, rational drug design, as well as the role of inflammation in chronic lung diseases. Due to his expertise on rational drug design, he joined the team of CuraVac, a Belgian pharmaceutical company, that used Blalock’s “vaccine production technique” in order to find medicaments to treat autoimmune diseases like myasthenia gravis.

Concerning his partner, Eric M. Smith, there is insufficient data on the internet to report on his full CV. However, at the time they met, he was a medical scientist at the Department of Microbiology, University of Texas Medical Branch, Galveston. Eric M. Smith is a renowned researcher in the field of neuroendocrine immunology. Together with J. Edwin Blalock, he published more than 40 papers on these subjects.

The discovery of Blalock and Smith

In the late 1970s, Blalock was interested in antiviral activities of interferons, and he observed that these lymphokines had “hormone-like activities” and hormones were shown to have cell-specific interferon-like activities (1). In a paper of 1980 (2), Blalock and Smith showed “strong antigenic relatedness among human leukocyte interferon, ACTH, and endorphins, implying that there are underlying structural similarities.” Later, IFN-α was cloned and analysis of the DNA showed that there were no ACTH sequences in the protein. Thus, structural relatedness was not the key solution to the problem. It seemed that ACTH was co-produced with IFN-α and present in the preparation at the same time. Indeed, the important paper showed that affinity purification and separation on SDS–polyacrylamide gels demonstrated that a 22-Kd biosynthetic intermediate of pro-opiomelanocortin (POMC, precursor of ACTH) had been co-purified with the 23-Kd form of IFN-α (3). Subsequent studies established that leukocyte ACTH was biologically active and antigenically identical to the pituitary peptide. Thus, leukocytes produce peptide hormones.

In this decisive work on leukocyte hormone production, the authors wrote: “The detection of ACTH and endorphin-like materials in lymphocytes demonstrates that the immune system can produce substances that are related to known polypeptide hormones and that are capable of signaling the neuroendocrine system.”

Based on these results, Blalock later developed the concept of the sixth sense (4,5). Through the sharing of ligands and receptors the immune system could serve as a sixth sense to detect things the body cannot otherwise hear, see, smell, taste or touch.

In one form or the other, the existence of hormone production in immune cells stood the test of time and some relevant experiments have also been published in Neuroimmunomodulation (6-11).

References

1. Blalock JE, Stanton JD. Common pathways of interferon and hormonal action. Nature. 1980;283(5745):406-408
2. Blalock JE, Smith EM. Human leukocyte interferon: structural and biological relatedness to adrenocorticotropic hormone and endorphins. Proc Natl Acad Sci U S A. 1980;77(10):5972-5974
3. Smith EM, Blalock JE. Human Leukocyte production of corticotropin and endorphin-like substances: Association with leukocyte interferon. Proc. Natl. Acad. Sci. USA 1981;78:7530-7534
4. Blalock JE. The syntax of immune-neuroendocrine communication. Immunol Today. 1994;15:504-511
5. Blalock JE, Smith EM. Conceptual development of the immune system as a sixth sense. Brain Behav Immun. 2007;21:23-33
6. Liu Q, Arkins S, Biragyn A, Minshall C, Parnet P, Dantzer R, Kelley KW. Competitive reverse transcriptase-polymerase chain reaction using a synthetic internal RNA standard to quantitate transcripts for leukocyte-derived hormones. Neuroimmunomodulation 1994;1:33-41
7. Rohn WM, Weigent DA. Cloning and nucleotide sequencing of rat lymphocyte growth hormone cDNA. Neuroimmunomodulation. 1995;2:108-114
8. Throsby M, Pleau J, Dardenne M, Homo-Delarche F. Thymic expression of the pancreatic endocrine hormones. Neuroimmunomodulation 1999;6:108-114
9. Weigent DA, Vines CR, Long JC, Blalock JE, Elton TS. Characterization of the promoter-directing expression of growth hormone in a monocyte cell line. Neuroimmunomodulation 2000;7:126-134
10. Arnold RE, Weigent DA. The inhibition of apoptosis in EL4 lymphoma cells overexpressing growth hormone. Neuroimmunomodulation 2004;11(3):149-159
11. Markus RP, Ferreira ZS, Fernandes PA, Cecon E. The immune-pineal axis: a shuttle between endocrine and paracrine melatonin sources. Neuroimmunomodulation 2007;14:126-133

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Pillar Articles: Leukocytes Produce Neurotransmitters Like Acetylcholine

Viewpoint On:

Dale HH, Dudley HW. The presence of histamine and acetylcholine in the spleen of the ox and the horse. J Physiol. 1929;68:97-123

Sir Henry Hallet Dale was born in 1875 in Islington, London, U.K. He visited Tollington Park College, The Leys School Cambridge, and in 1894 he entered Trinity College, Cambridge. In 1909, he received his Doctor of Medicine degree from Cambridge. Dale devoted his work to acetylcholine in studying its effects on various bodily functions (e.g., blood pressure). In parallel to this early work in the 1910s and 1920s, Otto Loewi (1873-1961) born in Frankfurt and working in Graz discovered that acetylcholine is a neurotransmitter from the vagus nerve (he called it the Vagusstoff). Dale and Loewi received the Nobel Prize in Physiology or Medicine in 1936 for their work on neurotransmission.

His partner in the publication of 1929 (1) was Harold Ward Dudley (1887-1935), born in Leeds, U.K. He studied chemistry at the University of Leeds, and he received his doctoral degree in chemistry in the environment of Emil Fischer at the University of Berlin in 1912. After a short stay in New York City and active participation in World War I, he joined the team of Henry Dale in the National Institute for Medical Research in Hampstead (London).

The discovery of Dale and Dudley

In their early paper of 1929, Dale and Dudley discovered, for the first time, acetylcholine in an animal body. For their discovery, they used the horse spleen, and they showed the physiological function of extracted acetylcholine (1). In this paper, they wrote in the discussion:

“It appears to us that the case for acetylcholine as a physiological agent is now materially strengthened by the fact that we have been able to isolate it from an animal organ and thus to show that it is a natural constituent of the body. We have yet no conception of the meaning of its presence in the spleens of these large ungulates [AU: hoofed animal].”

The discussion of the paper in 1929 clearly shows that Dale and Dudley had no idea why acetylcholine should be present in the spleen. They did not realize that it must be produced by immune or endothelial cells because their focus was not on the spleen as a reservoir of immune cells. Nevertheless, this first work clearly showed the non-neuronal acetylcholine release.

The discovery of acetylcholine in immune cells – Kawashima and colleagues

Today, we know that the spleen is not innervated by parasympathetic nerve fibers that carry acetylcholine as a neurotransmitter (3). Thus, production of acetylcholine in the spleen must depend on another cellular source. Indeed, acetylcholine can be produced from single cells very different from neuronal cells such as in fungi (4) or bacteria (5) (see also ref. 6 for more examples). The discovery of acetylcholine production in immune and endothelial cells lasted until the late 1980s and early 1990s (7-9). Today, we clearly recognize an extra-neuronal cholinergic system in immune cells (6). We also recognize immunomodulating effects through the nicotinic acetylcholine receptor alpha7 subunit (6, 10). Another neurotransmitter to be discovered in leukocytes was noradrenaline at the beginning of the 1990s (11,12). Release of acetylcholine in the spleen is independent of electrical tissue stimulation, which demonstrates its non-neuronal source (different for noradrenaline, ref. 13).

In one form or the other, the existence of the extra-neuronal cholinergic system in immune cells stood the test of time (6), and some relevant experiments have also been published in Neuroimmunomodulation (14-16).

References

1. Dale HH, Dudley HW. The presence of histamine and acetylcholine in the spleen of the ox and the horse. J Physiol. 1929;68:97-123
2. Dale HH. Harold Ward Dudley. 1887-1935. Obituary Notices of Fellows of the Royal Society 1935;1:595-606
3. Fujii T, Mashimo M, Moriwaki Y, Misawa H, Ono S, Horiguchi K, Kawashima K. Expression and function of the cholinergic system in immune cells. Front Immunol. 2017;8:1085. doi: 10.3389/fimmu.2017.01085
4. Ewins AJ. Acetylcholine, a new active principle of ergot. Biochem J. 1914;8:44-49
5. Stephenson M, Rowatt E. The production of acetylcholine by a strain of lactobacillus plantarum – with an addendum on the isolation of acetylcholine as a salt of hexanitrodiphenylamine by Alyne K. Harrison. J Gen Microbiol 1947;1:279-98
6. Kawashima K, Mashimo M, Nomura A, Fujii T. Contributions of Non-Neuronal Cholinergic Systems to the Regulation of Immune Cell Function, Highlighting the Role of α7 Nicotinic Acetylcholine Receptors. Int J Mol Sci. 2024;25:4564. doi: 10.3390/ijms25084564
7. Kawashima K, Oohata H, Fujimoto K, Suzuki T. Extraneuronal localization of acetylcholine and its release upon nicotinic stimulation in rabbits. Neurosci Lett. 1989;104:336-339
8. Kawashima K, Watanabe N, Oohata H, Fujimoto K, Suzuki T, Ishizaki Y, Morita I, Murota S. Synthesis and release of acetylcholine by cultured bovine arterial endothelial cells. Neurosci Lett. 1990;119:156-158
9. Kawashima K, Kajiyama K, Suzuki T, Fujimoto K. Presence of acetylcholine in blood and its localization in circulating mononuclear leukocytes of humans. Biog Amines 1993;9:251–258.
10. Wang H, Yu M, Ochani M, Amella CA, Tanovic M, Susarla S, Li JH, Wang H, Yang H, Ulloa L, Al-Abed Y, Czura CJ, Tracey KJ. Nicotinic acetylcholine receptor alpha7 subunit is an essential regulator of inflammation. Nature. 2003;421:384-388
11. Bergquist J, Tarkowski A, Ekman R, Ewing A. Discovery of endogenous catecholamines in lymphocytes and evidence for catecholamine regulation of lymphocyte function via an autocrine loop. Proc Natl Acad Sci U S A. 1994;91:12912-12916
12. Josefsson E, Bergquist J, Ekman R, Tarkowski A. Catecholamines are synthesized by mouse lymphocytes and regulate function of these cells by induction of apoptosis. Immunology 1996;88:140-146
13. Straub RH, Rauch L, Fassold A, Lowin T, Pongratz G. Neuronally released sympathetic neurotransmitters stimulate splenic interferon-gamma secretion from T cells in early type II collagen-induced arthritis. Arthritis Rheum. 2008;58:3450-3460
14. Rinner I, Globerson A, Kawashima K, Korsatko W, Schauenstein K. A possible role for acetylcholine in the dialogue between thymocytes and thymic stroma. Neuroimmunomodulation. 1999;6:51-55.
15. van der Zanden EP, Hilbers FW, Verseijden C, van den Wijngaard RM, Skynner M, Lee K, Ulloa L, Boeckxstaens GE, de Jonge WJ. Nicotinic acetylcholine receptor expression and susceptibility to cholinergic immunomodulation in human monocytes of smoking individuals. Neuroimmunomodulation. 2012;19:255-265
16. Aripaka SS, Mikkelsen JD. Anti-Inflammatory Effect of Alpha7 Nicotinic Acetylcholine Receptor Modulators on BV2 Cells. Neuroimmunomodulation. 2020;27:194-202

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Pillar Articles: Behavioral Conditioned Immunosuppression – The Anti-Metalnikov Effect

Viewpoint On:

Ader R. Letter: Behaviorially conditioned immunosuppression. Psychosom Med. 1974;36:183-184

Ader R, Cohen N. Behaviorally conditioned immunosuppression. Psychosom Med. 1975;37:333-340

Robert “Bob” Ader was born in 1932 in the Bronx, New York City. He graduated from the Horace Mann School, a remarkable place of famous alumni (1). In 1953, he finished a bachelor’s degree in psychology from Tulane University in New Orleans. He earned the Ph.D. in psychology from Cornell University in 1957. After moving to Rochester, state of New York, Robert Ader spent his entire career at the University of Rochester. He was director of the Division of Behavioral and Psychosocial Medicine in the University of Rochester’s department of psychology and director of the Center for Psychoneuroimmunology Research. He died in December 2011 in the age of 79.

His partner Nicolas Cohen was born in 1938. He received his bachelor in biology from Princeton University in 1959 and his Ph.D. from the University of Rochester, N.Y., in 1966. Between 1965 and 1967, as a postdoctoral scholar, he trained in microbiology and immunology at the University of California in Los Angeles. He joined the University of Rochester, N.Y., Department of Microbiology and Immunology in 1967. He took a sabbatical at the Basel Institute for Immunology, Basel, Switzerland in 1975-76. He was Director of the Division of Immunology (1979-2004). He retired in 2004.

The Idea of Ader and Cohen

While Metalnikov and Chorine in the late 1920s demonstrated conditioned immunoactivation (2), Ader and Cohen focused on immunosuppression. The first important paper of the two authors appeared in 1975 (3). In this paper, they described that an illness-induced taste aversion was conditioned in rats by pairing saccharin with cyclophosphamide, an immunosuppressive agent. To induce a clearly defined immunological readout, they injected sheep red blood cells into the animals that induced hemagglutinating antibodies measured 6 days after antigen administration. High titers were observed in placebo-treated rats, in non-conditioned animals and in conditioned animals that were not subsequently exposed to saccharin. No agglutinating antibody was detected in conditioned animals treated with cyclophosphamide at the time of antigen administration (positive control to show immunosuppression through the agent). Conditioned animals exposed to saccharin at the time of or following the injection of antigen were significantly immunosuppressed (the important conditioned group). For the first time, these data showed strong inhibition of the immune system through Pavlovian conditioning. It complemented the work of Metalnikov and Chorine form the late 1920s (the anti-Metalnikov effect). This work was replicated one year later (4). Important studies of Ader and Cohen followed (5, 6).

In a review paper, Ader wrote (7) “This study (3) demonstrated that, like other physiological processes, the immune system was subject to classical (Pavlovian) conditioning, providing dramatic evidence of an inextricable relationship between the brain and the immune system.”

In one form or the other, immune conditioning stood the test of time (8), and some of the experiments have also been published in Neuroimmunomodulation (9-15).

References

1. https://en.wikipedia.org/wiki/List_of_Horace_Mann_School_alumni
2. Metalnikov S, Chorine V. Role des reflexes conditionnels dans l’immunite. Ann Inst Pasteur (Paris) 1926;40:893–900 [we reported on Metalnikov / Chorine in a special Pillar Article]
3. Ader R, Cohen N. Behaviorally conditioned immunosuppression. Psychosom Med. 1975;37:333-340
4. Rogers MP, Reich P, Strom TB, Carpenter CB. Behaviorally conditioned immunosuppression: replication of a recent study. Psychosom Med. 1976;38:447-451
5. Bovbjerg D, Ader R, Cohen N. Behaviorally conditioned suppression of a graft-versus-host response. Proc Natl Acad Sci U S A. 1982;79:583-585
6. Ader R, Cohen N. Behaviorally conditioned immunosuppression and murine systemic lupus erythematosus. Science. 1982;215:1534-1536
7. Ader R. Historical perspectives on psychoneuroimmunology. In: Friedman TW, Klein AL, Friedman AL (Eds.) Psychoneuroimmunology, stress and infection. CRC Press, Boca Raton, 1995, pp. 1-21.
8. Hadamitzky M, Lückemann L, Pacheco-López G, Schedlowski M.: Pavlovian Conditioning of Immunological and Neuroendocrine Functions. Physiol Rev. 2020;100:357-405
9. Bauer D, Busch M, Pacheco-López G, Kasper M, Wildschütz L, Walscheid K, Bähler H, Schröder M, Thanos S, Schedlowski M, Heiligenhaus A.: Behavioral conditioning of immune responses with cyclosporine a in a murine model of experimental autoimmune uveitis. Neuroimmunomodulation. 2017;24:87-99
10. Vidal J, Chamizo VD.: The conditioned stimulus elicits taste aversion but not sickness behavior in conditioned mice. Neuroimmunomodulation. 2010;17:325-32
11. Pacheco-López G, Niemi MB, Kou W, Baum S, Hoffman M, Altenburger P, del Rey A, Besedovsky HO, Schedlowski M.: Central blockade of IL-1 does not impair taste-LPS associative learning. Neuroimmunomodulation. 2007;14:150-156
12. Haour F.: Mechanisms of the placebo effect and of conditioning. Neuroimmunomodulation. 2005;12:195-200
13. Mei L, Li L, Li Y, Deng Y, Sun C, Ding G, Fan S.: Conditioned immunosuppressive effect of cyclophosphamide on delayed-type hypersensitivity response and a preliminary analysis of its mechanism. Neuroimmunomodulation. 2000;8:45-50
14. Exton MS, von Hörsten S, Strubel T, Donath S, Schedlowski M, Westermann J.: Conditioned alterations of specific blood leukocyte subsets are reconditionable. Neuroimmunomodulation. 2000;7:106-14
15. Rogers CF, Ghanta VK, Demissie S, Hiramoto N, Hiramoto RN.: Lidocaine interrupts the conditioned natural killer cell response by interfering with the conditioned stimulus. Neuroimmunomodulation. 1994;1:278-83

(Featured image declaration: by Alan O’Rourke from flickr.com)

Pillar Articles: Adrenergic Modulation of Leukocytes – anni mirabiles 1968 to 1970

Viewpoint On

Szentvanyi A. The beta-adrenergic theory of the atopic abnormality in bronchial asthma. J Allergy 1968;42:203-232

Benner MH, Enta T, Lockey Jr S, Makino S, Reed CE. The immunosuppressive effect of epinephrine and the adjuvant effect of beta-adrenergic blockade. J Allergy 1968;41:110-111 (Abstract – never published in paper form)

Smith JW, Steiner AL, Newberry Jr. WM, Parker CW. Cyclic nucleotide inhibition of lymphocyte transformation. Clin. Res. 1969;17:549 (Abstract – later published in J Clin Invest. 1971;50:432-441)

May CD. Effects of compounds which inhibit lymphocyte stimulation on the utilization of glucose by leukocytes. J Allergy 1970;46:21-28

Hadden JW, Hadden EM, Middleton E Jr. Lymphocyte blast transformation. I. Demonstration of adrenergic receptors in human peripheral lymphocytes. Cell Immunol. 1970;1:583-595

For this 7^th Pillar Article Series, the editor found it extremely difficult to just mention one single author or a single author group that started “adrenergic modulation of leukocytes”. Therefore, the presentation differs from the usual report.

Andras Szentvanyi is credited for his insight into beta-adrenergic mechanisms in asthma where he clearly mentioned the beta-adrenergic effect on cell proliferation (1). This publication was seen as a theoretical starter although the author already had long-standing experiences on adrenergic effects in asthma. In this publication, Szentvanyi wisely summarized the effect on mitosis of adrenergically-induced intracellular glucose changes, which was studied early in non-immune cells such as fibroblasts (2). Two important abstracts given on research conferences showed inhibitory effects of adrenaline and cyclic adenosine monophosphate (cAMP) on leukocyte proliferation (3, 4). Glucose utilization was again an important aspect for lymphocyte proliferation, and cAMP was inhibitory in experiments with phytohemagglutinin-stimulated cells (5).

With this information present, it was John W. Hadden (23. Oct. 1939 – 1. April 2013) and colleagues in 1970 who showed very clear effects of adrenergic compounds on phytohemagglutinin-stimulated leukocyte proliferation (6). He observed inhibitory effects through β-adrenergic pathways (think of the cAMP effects from above because that is the canonic signaling pathway) and mainly stimulatory effects through α‑adrenergic pathways (inhibition of cAMP). The studies were carried out with tritiated thymidine incorporation into peripheral blood leukocyte cells of healthy donors.

The groups around Charles W. Parker (St. Louis, USA), Charles E. Reed (Wisconsin, USA) and Charles D. May (New York, USA) lost more and more contact to adrenergic immunomodulation. They were strong allergologists, and this field moved on to more immunological and therapeutic aspects of allergy. In contrast, John W. Hadden remained faithful to neuroimmunomodulation for one more decade before he moved to drugs and biologicals for immunotherapy. In 1993, he formed a biotech company that focused on immunotherapy of cancer and infection. He and Andras Szentvanyi edited the first and second volume of Immunopharmacology Reviews in 1990 and 1996, respectively.

The journal Neuroimmunomodulation published more than 80 papers related to the link between catecholamines and immunomodulation, some of which are given in the reference list (7-11).

References

1. Szentvanyi A. The beta-adrenergic theory of the atopic abnormality in bronchial asthma. J Allergy 1968;42:203-232
2. Lettré H, Albrecht M. Zur Wirkung von β-Phenyläthylaminen auf in vitro gezüchtete Zellen. Hoppe-Seylers Zeitschrift f. physiol. Chemie (now: Biological Chemistry) 1941;271:200-207
3. Benner MH, Enta T, Lockey Jr S, Makino S, Reed CE. The immunosuppressive effect of epinephrine and the adjuvant effect of beta-adrenergic blockade. J Allergy 1968;41:1110-111 (Abstract)
4. Smith JW, Steiner AL, Newberry Jr. WM, Parker CW. Cyclic nucleotide inhibition of lymphocyte transformation. Clin. Res. 1969;17:549 (Abstract)
5. May CD. Effects of compounds which inhibit lymphocyte stimulation on the utilization of glucose by leukocytes. J Allergy 1970;46:21-28
6. Hadden JW, Hadden EM, Middleton E Jr. Lymphocyte blast transformation. I. Demonstration of adrenergic receptors in human peripheral lymphocytes. Cell Immunol. 1970;1:583-595
7. Genaro AM, Cremaschi GA, Gorelik G, Sterin-Borda L, Borda ES. Downregulation of beta adrenergic receptor expression on B cells by activation of early signals in alloantigen-induced immune response. 2000;8:114-21
8. Page GG, Ben-Eliyahu S. Natural killer cell activity and resistance to tumor metastasis in prepubescent rats: deficient baselines, but invulnerability to stress and beta-adrenergic stimulation. 2000;7:160-168
9. Oberbeck R, Schmitz D, Wilsenack K, Schüler M, Pehle B, Schedlowski M, Exton MS. Adrenergic modulation of survival and cellular immune functions during polymicrobial sepsis. 2004;11:214-223
10. Kitamura H, Shiva D, Woods JA, Yano H. Beta-adrenergic receptor blockade attenuates the exercise-induced suppression of TNF-alpha in response to lipopolysaccharide in rats. 2007;14:91-96
11. Straub RH, Dufner B, Rauch L. Proinflammatory α-Adrenergic Neuronal Regulation of Splenic IFN-γ, IL-6, and TGF-β of Mice from Day 15 onwards in Arthritis. Neuroimmunomodulation. 2020;27:58-68