Craig Sharkey

Catecholamines mediate stress-induced increases in peripheral and central inflammatory cytokines.

Proinflammatory cytokines act at receptors in the CNS to alter physiological and behavioral responses. Exposure to stressors increases both peripheral and central proinflammatory cytokines, yet the mechanism(s) of induction remain unknown. Experiments here examined the role of catecholamines in the in vivo induction of proinflammatory cytokines following tailshock stress. Rats were pretreated i.p. with 2.0 mg/kg prazosin (alpha1-adrenoceptor antagonist), 10.0 mg/kg propranolol (beta-adrenoceptor antagonist), or 5.0 mg/kg labetalol (alpha1- and beta-adrenoceptor antagonist) 30 min prior to tailshock exposure and plasma interleukin-1beta (IL-1beta) and IL-6, along with tissue interleukin-1beta from the hypothalamus, hippocampus, and pituitary were measured immediately following stressor termination. Prazosin attenuated stress-induced plasma IL-1beta and IL-6, but had no effect on tissue IL-1beta levels, while propranolol attenuated plasma IL-6 and blocked tissue IL-1beta elevation, and labetalol, which cannot cross the blood-brain barrier, attenuated plasma IL-1beta and IL-6, blocked pituitary IL-1beta, but had no effect on central tissue IL-1beta levels. Furthermore, administration of 50.0 mg/kg N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride, a neurotoxin that lesions neural projections from the locus coeruleus, prevented stress-induced elevation in hippocampal IL-1beta, a region highly innervated by the locus coeruleus, but had no effect on hypothalamic IL-1beta, a region that receives few locus coeruleus projections. Finally, i.p. injection of 5.0 mg/kg isoproterenol (beta-adrenoceptor agonist) was sufficient to induce circulating IL-1 and IL-6, and tissue IL-1beta. These data suggest catecholamines play an important role in the induction of stress-induced proinflammatory cytokines and that beta-adrenoceptors are critical for tissue IL-1beta induction, while both alpha- and beta-adrenoceptors contribute to the induction of plasma cytokines.

Splenic norepinephrine depletion following acute stress suppresses in vivo antibody response

Exposure to an intense acute stressor immediately following immunization leads to a reduction in anti-KLH IgM, IgG, and IgG2a, but not IgG1. Stress also depletes splenic norepinephrine (NE) content. Immunization during pharmacological (alpha-methyl-p-tyrosine) or stress-induced splenic NE depletion results in antibody suppression similar to that found in rats immunized prior to stressor exposure. Prevention of splenic NE depletion during stress by tyrosine, but not pharmacological elevation (mirtazapine) of NE, resulted in normal antibody responses. These data support the hypothesis that splenic NE depletion is necessary and sufficient for stress-induced suppression of antibody to a T-cell dependent antigen.

Stress-induced facilitation of host response to bacterial challenge in F344 rats is dependent on extracellular heat shock protein 72 and independent of alpha beta T cells

Activation of the in vivo stress response can facilitate antibacterial host defenses. One possible mechanism for this effect is stress-induced release of heat shock protein 72 (Hsp72) into the extracellular environment. Hsp72 is a ubiquitous cellular protein that is up-regulated in response to cellular stress, and modulates various aspects of immune function including macrophage inflammatory/bactericidal responses and T-cell function when found in the extracellular environment. The current study tested the hypothesis that in vivo extracellular Hsp72 (eHsp72) at the site of inflammation contributes to stress-induced restricted development of bacteria, and facilitated recovery from bacteria-induced inflammation, and that this effect is independent of alpha beta (αβ) T cells. Male F344 rats were exposed to either inescapable electrical tail-shocks or no stress, and subcutaneously injected with Escherichia coli (ATCC 15746). The role of eHsp72 was investigated by Hsp72-immunoneutralization at the inflammatory site. The potential contribution of T cells was examined by testing male athymic (rnu/rnu) nude rats lacking mature αβ T cells and heterozygous thymic intact control (rnu/+) rats. The results were that stressor exposure increased plasma concentrations of eHsp72 and facilitated recovery from bacterial inflammation. Immunoneutralization of eHsp72 at the inflammatory site attenuated this effect. Stressor exposure impacted bacterial inflammation and eHsp72 equally in both athymic and intact control rats. These results support the hypothesis that eHsp72 at the site of inflammation, and not αβ T cells, contributes to the effect of stressor exposure on subcutaneous bacterial inflammation.

Splenic norepinephrine depletion suppresses in vivo antibody response in physically active animals

dritic cell (DC). These studies aimed to understand how melatonin affects DCs’ differentiation and maturation using an in vitro bone marrow dendritic cells (BMDC) culture system. Since melatonin has also been shown to regulate the stress-induced hormone corticosterone (CORT), CORT was also included in the study. It was found that 24 h pretreatment with melatonin caused dose-responsive enhancement of LPS-induced DC maturation, while CORT, as expected, caused dose-responsive inhibition of DC maturation. Furthermore, DCs exposed to moderate amounts of melatonin greatly increased their IL-12 production. On the other hand, when BM cells were treated with hormones throughout the culture period without LPS stimulation, their development into DCs was not affected by melatonin, but was negatively affected by CORT. Surprisingly, when both hormones were applied, the effects of CORT were dominant in all cases. All together, melatonin positively regulates DCs during immune responses, but does not influence the CORT’s effects on DCs. Continuing studies will help the arising clinical use of DCs.

Regulation of brain IL-1 production following peripheral E. coli challenge: A role for the nucleus tractus solitarius and locus coeruleus

The relationship between stress and post-surgical WBC count among women undergoing total abdominal hysterectomy with bilateral salpingo oophorectomy (TAH-BSO) for suspected endometrial cancer Sally E. Jensen , Deidre B. Pereira , Stacy M. Dodd , Melissa Hosonitz , Daylene Ripley , Linda Morgan b a Department of Clinical and Health Psychology, University of Florida, USA b Department of Obstetrics and Gynecology, University of Florida, USA

102 The female intracellular Hsp72 stress response

ther the immunoregulatory effects of counter-irritation, we have tested the effects of turpentine injections into themuscle (IM), skin (ID)or plantar foot (PF) of the hindlimbof rats on endotoxin (LPS) induced plasma and splenic cytokines and catecholamine levels and plasma corticosterone. One hour following saline or turpentine injections (50–100 ll), rats were injected IV with LPS (10 lg) and then sacrificed one hour later. Relative to saline injections, both IM and PF injections of turpentine produced a significant decrease in plasma and splenic levels of TNF protein whereas IL-1 and IL-6 levels were unaltered by pretreatment with turpentine. In addition, PF injections of turpentine produced a significant decrease of corticosterone levels. In contrast, the effects of ID injections of turpentine were limited to a significant increase in splenic TNF levels and a tendency to increase plasma TNF levels. To examine the role of the sympathetic nervous system, we pretreated rats IP with the peripheral beta-adrenergic blocking agent Nadolol (2 mg/kg) 30 min prior to an IM injection of saline or turpentine. LPS was injected 1 h post-turpentine/saline and the rats were sacrificed one hour later. Pretreatment with Nadolol blocked the suppression in splenic and plasma levels of TNF produced by IM turpentine, consistent with the sympathetic mediation of the immunoregulatory effects of counter-irritation. Our data indicate further that the immunomodulatory effects of ID turpentine may be quite distinct from that observed with IM and PF injections. Supported by the NIMH of the United States (MH 43778).

40 Activation of the acute stress response promotes host defense and T cell dependent immunological memory against bacterial challenge

role in the development of IFN-a (cytokine)-induced behavioral change. To further explore the potential role of CRF in IFN-a-induced behavioral alterations, we have examined IFN-a-induced neuroendocrine, immune, and behavioral responses in rhesus monkeys. To first determine whether IFN-a activates relevant signaling pathways in rhesus monkeys, we evaluated the expression of phosphoSTAT1 (a major signaling pathway activated by IFN-a) in monkey peripheral blood mononuclear cells (PBMCs) treated with rHu-IFN-a (1000 IU/ml) in vitro using both flow cytometry and Western blot. IFN-a increased phospho-STAT-1 in monkey PBMCs at 15, 30, and 60 min, a pattern similar to that seen in humans. We then investigated the acute and chronic effects of IFN-a on neuroendocrine, immune, and behavioral responses in these animals. Consistent with the activation of upstream neuroendocrine secretagogues including CRF, acute administration of IFN-a (10 and 20 MIU/m2) to rhesus monkeys markedly increased ACTH and cortisol as well as IL-6 compared to saline in 8 young adult (6 male, 2 female) animals. We additionally treated 4 monkeys (2 male and 2 female), with IFN-a (20 MIU/m2) or saline for 4 weeks. Interestingly, the neuroendocrine and immune responses to chronic IFN-a exposure in monkeys appeared to depend on the social status of the animal. Whereas acute elevations in cortisol, ACTH, and IL-6 concentrations returned to saline levels by week 2 in dominant animals, the concentration of these hormones remained high throughout IFN-a treatment in subordinant animals. Behavioral changes included the induction of huddling (2 out 4 animals) and marked aggressive behavior in one of the dominant monkeys. Neither aggression nor huddling was present during saline treatment. Of note huddling has been previously described in monkeys treated with icv CRF. Taken together, these data provide evidence that rhesus monkeys exhibit similar immune, neuroendocrine, and behavioral responses to IFN-a as humans, and support the idea that activation of CRF pathways may be involved. Future studies using CRF antagonists will further elucidate the role of CRF in IFN-a induced neuroendocrine, immune, and behavioral changes, thus providing insight into novel approaches to the treatment of cytokine-induced behavioral syndromes.