Psychoneuroimmunology: stress effects on pathogenesis and immunity during infection

Health and growth of veal calves fed milk replacers with or without probiotics

Four experiments with 1-wk-old veal calves were conducted to assess the influence of probiotics on growth and health indicators. In experiments 1 and 2, the liquid probiotic supplements were administered daily from experimental d 1 to 15. The treatment period in experiments 3 and 4 was extended to 56 d. The probiotics used were a multispecies probiotic (MSPB) containing different probiotic species of human origin, or a calf-specific probiotic (CSPB) containing 6 Lactobacillus species isolated from calf feces and selected on the basis of a combination of characteristics. When the data for the 4 experiments were pooled, the probiotics enhanced growth rate during the first 2 wk. During the 8-wk experimental period, average daily gain and feed efficiency were significantly improved in the probiotic-treated groups. The MSPB-induced increase in weight gain was greater when the control calves were considered less healthy based on a health score (an index of diarrhea and therapeutic treatments). Probiotic treatment tended to diminish mortality. The CSPB treatment reduced the incidence of diarrhea and the fecal counts of coliforms. When therapeutic treatment was intensive in the control calves, the ingestion of probiotics reduced the percentage of calves that required therapy and the amount of treatments needed against digestive or respiratory diseases. There was no clear difference in the efficiency of the MSPB and CSPB preparations. Further research is necessary to identify underlying mechanisms and to evaluate the potential of probiotics to improve respiratory health in veal calf production.

Bidirectional communication between the brain and the immune system: implications for physiological sleep and disorders with disrupted sleep

This review describes mechanisms of immune-to-brain and brain-to-immune signaling involved in mediating physiological sleep and altered sleep with disease. The central nervous system (CNS) modulates immune function by signaling target cells of the immune system through autonomic and neuroendocrine pathways. Neurotransmitters and hormones produced and released by these pathways interact with immune cells to alter immune functions, including cytokine production. Cytokines produced by cells of the immune and nervous systems regulate sleep. Cytokines released by immune cells, particularly interleukin-1beta and tumor necrosis factor-alpha, signal neuroendocrine, autonomic, limbic and cortical areas of the CNS to affect neural activity and modify behaviors (including sleep), hormone release and autonomic function. In this manner, immune cells function as a sense organ, informing the CNS of peripheral events related to infection and injury. Equally important, homeostatic mechanisms, involving all levels of the neuroaxis, are needed, not only to turn off the immune response after a pathogen is cleared or tissue repair is completed, but also to restore and regulate natural diurnal fluctuations in cytokine production and sleep. The immune system's ability to affect behavior has important implications for understanding normal and pathological sleep. Sleep disorders are commonly associated with chronic inflammatory diseases and chronic age- or stress-related disorders. The best studied are rheumatoid arthritis, fibromyalgia and chronic fatigue syndromes. This article reviews our current understanding of neuroimmune interactions in normal sleep and sleep deprivation, and the influence of these interactions on selected disorders characterized by pathological sleep.

State and trait affect as predictors of salivary cortisol in healthy adults

We measured affect in 334 healthy adults on each of 7 days over a 3-week period. On the last day, salivary cortisol was assessed 14 times yielding scores for total concentration, morning rise amplitude, and slope of the time function. Trait negative affect (NA) was associated with higher total cortisol concentrations and greater morning rise in men. Cortisol levels for men low in trait positive affect (PA) did not decrease in the afternoon, resulting in a relatively high, flat rhythm. In contrast, women high in trait PA had low morning cortisol resulting in a low flat rhythm. State (person-centered) NA was not associated with same-day cortisol measures. State PA was associated with decreased total cortisol concentration in women. These are the first results showing associations between cortisol and trait PA. Differences in rhythmicity found here are noteworthy given the possible role of cortisol dysregulation in disease incidence, morbidity, mortality, and severity.

The complementarity model of brain–body relationship

We introduce the complementarity concept to understand mind-body relations and the question why the biopsychosocial model has in fact been praised, but not integrated into medicine. By complementarity, we mean that two incompatible descriptions have to be used to describe something in full. The complementarity model states that the physical and the mental side of the human organism are two complementary notions. This contradicts the prevailing materialist notion that mental and psychological processes are emergent properties of an organism. The complementarity model also has consequences for a further understanding of biological processes. Complementarity is a defining property of quantum systems proper. Such systems exhibit correlated properties that result in coordinated behavior without signal transfer or interaction. This is termed EPR-correlation or entanglement. Weak quantum theory, a generalized version of quantum mechanics proper, predicts entanglement also for macroscopic systems, provided a local and a global observable are complementary. Thus, complementarity could be the key to understanding holistically correlated behavior on different levels of systemic complexity.

Shingles Immunity and Health Functioning in the Elderly: Tai Chi Chih as a Behavioral Treatment

Both the incidence and severity of herpes zoster (HZ) or shingles increase markedly with increasing age in association with a decline in varicella zoster virus (VZV)-specific immunity. Considerable evidence shows that behavioral stressors, prevalent in older adults, correlate with impairments of cellular immunity. Moreover, the presence of depressive symptoms in older adults is associated with declines in VZV-responder cell frequency (VZV-RCF), an immunological marker of shingles risk. In this review, we discuss recent findings that administration of a relaxation response-based intervention, tai chi chih (TCC), results in improvements in health functioning and immunity to VZV in older adults as compared with a control group. TCC is a slow moving meditation consisting of 20 separate standardized movements which can be readily used in elderly and medically compromised individuals. TCC offers standardized training and practice schedules, lending an important advantage over prior relaxation response-based therapies. Focus on older adults at increased risk for HZ and assay of VZV-specific immunity have implications for understanding the impact of behavioral factors and a behavioral intervention on a clinically relevant end-point and on the response of the immune system to infectious pathogens.

The interaction of social network size and stressful life events predict delayed-type hypersensitivity among women with metastatic breast cancer

This study examined relationships between social support, stressful life events and antigen-specific cell-mediated immunity. Participants were 72 women with documented metastatic breast carcinoma, who completed self-report measures of social support and life stress. Immune response was assessed using the delayed type hypersensitivity (DTH) skin test. Number of positive antigens was significantly related to the interaction of social network size and stressful life events (p<0.05). Number of positive antigens was greater for women who had experienced a high frequency of stressful life events but who reported a larger network of support. However, social network size was inversely related to DTH response among women who had experienced fewer stressful life events. Average induration size was not significantly related to the quality of social support, life stress per se, or their interactions. The relationship between social network size and immune response in women with metastatic breast cancer depends on prior stressful life experience.

Psychological risk factors for HIV pathogenesis: mediation by the autonomic nervous system

BACKGROUND

Epidemiologic studies have identified psychological risk factors for specific physical diseases, but the biological mechanisms mediating these relationships remain poorly defined.

METHODS

Social inhibition and autonomic nervous system (ANS) activity were assessed on multiple occasions in 54 gay men with asymptomatic human immunodeficiency virus (HIV) infection. Following baseline ANS assessment, plasma HIV-1 viral load and CD4+ T cell levels were monitored for 12-18 months to assess relationships between ANS activity and HIV pathogenesis.

RESULTS

We confirmed the previously reported relationship between socially inhibited temperament and vulnerability to viral pathology. Plasma viral load set-point was elevated eight-fold in socially inhibited individuals, and these individuals showed poorer virologic and immunologic response to initiation of highly active antiretroviral therapy (HAART). Effects were independent of duration of infection, HAART regimen, demographic characteristics, and health-relevant behavior. Neurophysiologic assessments documented elevated ANS activity in socially inhibited individuals, and mediational analyses showed that such differences could account for 64%-92% of the covariance between social inhibition and virologic parameters.

CONCLUSIONS

These data provide the first clinical evidence that differential neural activity mediates relationships between psychological risk factors and infectious disease pathogenesis. Such findings also suggest novel targets for adjunctive therapy in long-term control of HIV-1 disease.

Self reported stressful life events and exacerbations in multiple sclerosis: prospective study

OBJECTIVE

To study the relation between self reported stressful life events not related to multiple sclerosis and the occurrence of exacerbations in relapsing-remitting multiple sclerosis.

DESIGN

Longitudinal, prospective cohort study.

SETTING

Outpatient clinic of department of neurology in the Netherlands.

PARTICIPANTS

Patients aged 18-55 with relapsing-remitting multiple sclerosis, who could walk with a cane or better (score of 0-6.0 on the expanded disability status scale), and had had at least two exacerbations in 24 months before inclusion in the study. Patients with other serious conditions were excluded.

MAIN OUTCOME MEASURE

The risk of increased disease activity as measured by the occurrence of exacerbations after weeks with stressful events.

RESULTS

Seventy out of 73 included patients (96%) reported at least one stressful event. In total, 457 stressful life events were reported that were not related to multiple sclerosis. Average follow up time was 1.4 years. Throughout the study, 134 exacerbations occurred in 56 patients and 136 infections occurred in 57 patients. Cox regression analysis with time dependent variables showed that stress was associated with a doubling of the exacerbation rate (relative risk 2.2, 95% confidence interval 1.2 to 4.0, P = 0.014) during the subsequent four weeks. Infections were associated with a threefold increase in the risk of exacerbation, but this effect was found to be independent of experienced stress.

CONCLUSION

Stressful events were associated with increased exacerbations in relapsing-remitting multiple sclerosis. This association was independent of the triggering effect of infections on exacerbations of multiple sclerosis.

Chronic psychosocial stress-induced down-regulation of immunity depends upon individual factors

The effect of chronic stress on immune functions is strongly biased by individual factors. Mice were subjected to a new model of chronic psychosocial stress in which four different subcategories of stressed animals may be identified: Resident Dominants (RD), Resident Subordinates (RS), Intruder Dominants (InD), and Intruder Subordinates (InS). After 7 days of stress, mice were immunized with keyhole limpet hemocyanine (KLH). Their immune functions were investigated 14 days later with stress continuing trough. Importantly, RS mice, which are mice losing territory ownership, were the more affected, having lower IgG, proliferation, and IL-2. RD and InD showed lower IgG while InS showed no immune alteration. In conclusion, loss of resources could be a key factor in determining individual vulnerability to stressful events.

Effect of transportation and commingling on the acute-phase protein response, growth, and feed intake of newly weaned beef calves

The objective of this study was to investigate the effect of transportation and commingling on measures of the acute-phase protein response in newly weaned beef calves. Thirty-two (Exp. 1; average BW = 266 +/- 20.8 kg) and thirty-six (Exp. 2; average BW = 222 +/- 34.6 kg) Brahman-crossbred calves were randomly allotted to one of four treatments (2 x 2 factorial arrangement [transportation x commingling] in a completely randomized design). Body weight and jugular blood were collected at weaning, after shipment, and 1, 3, and 7 d after transport for Exp. 1, and at weaning and 1, 5, 9, 13, 17, and 21 d after transport for Exp. 2. Feed intake within pen was recorded daily for Exp. 2. Plasma fibrinogen, ceruloplasmin, haptoglobin, and cortisol concentrations were determined for all collection times. Additionally, serum amyloid-A and alpha-acid glycoprotein concentrations were determined in Exp. 1 and 2, respectively. In Exp. 2, commingled calves tended (P = 0.13) to have a higher DMI than noncommingled calves (5.3 and 4.8 kg/d, respectively). Transported calves lost more BW than nontransported calves from the time of weaning to d 1 (2.0 and 3.1% more BW loss for Exp. 1 and 2, respectively). With the exception of haptoglobin in Exp. 1, each of the acute-phase proteins measured in these studies increased over each sampling day. In Exp. 1, transported calves had higher (P < 0.05) mean serum amyloid-A concentrations than nontransported calves (48.9 vs. 33.4 microg/mL). There was a significant sampling day x transportation interaction (P < 0.01) for fibrinogen, ceruloplasmin, and haptoglobin in Exp. 1; transported calves had higher concentrations of fibrinogen following transport and on d 2 and 3, and ceruloplasmin on d 3. Haptoglobin concentrations were higher (P = 0.04) in nontransported calves on d 1 and 2 of Exp. 1. In Exp. 2, overall mean haptoglobin concentrations were higher in nontransported vs. transported calves. The results of these studies indicate that stressors associated with transportation affect the acute-phase protein response in newly weaned beef calves. More research is needed to determine whether these proteins might be valuable indicators of stress following the weaning process.

Coping with melanoma--ten strategies that promote psychological adjustment

The coping strategies discussed above are not right for everyone, but there is good evidence that they are generally helpful to patients who are dealing with cancer, including melanoma. The bottom line is that these strategies help patients feel better and stronger. They feel better because they are facing the illness squarely and working through its emotional impacts, and yet also keeping a perspective on it so that it does not define them or take over their lives. Through all the trials and challenges that cancer can bring, they are keeping their wits about them and able to carry on. They feel stronger because they have support, from other people and from within themselves. They have taken stock of their most cherished reasons for living, which strengthens and sustains them in their fight against cancer. And yet they also feel that their survival is not the only important objective; the quality of their lives and relationships, the values they live by, and their spirituality also deserve attention and effort. They have the peace of knowing that their death from cancer, if it comes to that, will not obliterate the meaning, value, and joy that their life has given to them and their loved ones.

The effect of chronic emotional stress on the humoral immune response to Porphyromonas gingivalis in mice

Previous studies have shown that psychological stress plays a significant role in the outcome of infectious diseases, but data related to the effect of stress on periodontal infection is limited. The present study was designed to test the impact of emotional stress on the humoral immune response to the periodontal pathogen Porphyromonas gingivalis in a mouse model of local inflammation. Chambers constructed from titanium wire were implanted in the subcutaneous dorsolumbar region of mice. All mice were immunized with P. gingivalis followed by an intrachamber challenge with the bacteria. One group of mice was used as control, while the other two experienced experimental stress conditions (isolation/restraint stress). Stress-1 group was stressed during the immunization period, while Stress-2 group was stressed during the local challenge period. Chamber exudates and serum were collected and analyzed for levels of anti-P. gingivalis antibodies (IgG, IgG1 and IgG2a). The levels of serum antibodies to P. gingivalis were not different between the three tested groups, excluding increased levels of IgG2a in Stress-1 group at baseline. The levels of antibodies in the chamber exudates were significantly lower in the stressed groups at baseline, but higher at d 7. The IgG1 to IgG2a ratio was significantly higher in the control group compared with the two stressed groups. The findings of the present study suggest that chronic psychological stress had a marked impact on the localized response to P. gingivalis challenge. The lower IgG1/IgG2a ratio observed in the stress groups suggests elevated Th1 response during stress.

Risk factors for postcraniotomy surgical site infection after 1,3-bis (2-chloroethyl)-1-nitrosourea (Gliadel) wafer placement

Gliadel wafers (1,3-bis [2-chloroethyl]-1-nitrosourea; Guilford Pharmaceuticals) are approved for the treatment of malignant gliomas; however, the incidence of and risk factors associated with infection with respect to this new technology are unknown. We identified 32 patients who received Gliadel wafers from December 1996 through October 1999. Nine patients (28%) developed >or=1 surgical site infection (SSI), which included 4 cases of brain abscess. All 3 patients who received vancomycin for surgical prophylaxis developed an SSI. In addition, multivariable analysis revealed an association between infection and a clinical diagnosis of depression. The National Nosocomial Infection Surveillance Surgical Site Index did not predict the onset of SSI after Gliadel wafer implantation. Patients who received a Gliadel wafer had a higher incidence of infection than previously has been reported, and additional studies are required to better quantify this risk and describe the epidemiology of such infections.

The promotion of tumor metastasis by surgery and stress: immunological basis and implications for psychoneuroimmunology

This mini-review emphasizes a psychoneuroimmunology (PNI) perspective of the hypothesis that stress and surgical excision of the primary tumor can promote tumor metastasis. It first establishes the empirical and theoretical basis for control of metastasis by cell-mediated immunity (CMI), as well as the interactive role of non-immunological risk factors. It then describes the various aspects of surgery that suppress CMI, and the neuroendocrine mechanisms mediating suppression by stress and surgery. Last, it briefly reviews the empirical evidence, from animal and human studies, for the promotion of metastasis by stress and surgery, with specific reference to the mediating role of CMI. It is concluded that: (a) Immunological mechanisms most likely play a role in limiting metastasis in patients with solid tumors. (b) Immunosuppression can be deleterious, especially when surgery is conducted early, before the tumor develops insurmountable mechanisms to escape immune destruction. (c) The most sensitive period for the establishment of metastases is the immediate aftermath of surgery. Interventions aiming at reducing stress and immunosuppression should thus strive to start beforehand. (d) 'Psychological and physiological insults activate similar neuroendocrine mechanisms of immunosuppression. Therefore, a multimodal therapeutic approach should be used to prevent tumor metastasis during the perioperative period. (e) Studies employing interventions aimed at reducing the surgical stress response should preferably assess immunological indices with an established clinical relevance, and follow up long-term recurrence provided sample size assure statistical power. (f) The progress toward earlier detection of cancer, and our growing understanding of immunosuppression, continuously improves the chances for successful PNI interventions.

Stress-associated immunomodulation and its implications for responses to vaccination

The rapidly growing field of psychoneuroimmunology involves the elucidation of the complex interactions between the CNS, the endocrine system and the immune system and its effects on health. Although the mechanisms involved in this bidirectional communication is not yet fully understood, studies in psychoneuroimmunology have shown that stress, through the hypothalamic-pituitary-adrenal and the sympathetic-adrenal-medullary axes, can induce modulation of the immune system. In this review, we discuss human studies and animal models, which focus on psychological stress and its effects on the immune response to vaccination, emphasizing the implications of these effects on health.

Phenotypic and functional changes on phagocytic cells recruited at the site of Candida albicans infection after chronic varied stress exposure

The transition of Candida albicans from commensalism to pathogenicity is associated with the immune status of the host; resistance to fungus involves macrophages (Mphi) and polymorphonuclear neutrophils (PMN), which act as effector cells. T-cell function is also involved. Previously, we found that in Wistar rats exposed to chronic varied stress (CVS) immediately after C. albicans infection (Ca-S group) some functions of phagocytic cells, such as killer activity and NO production, were strongly modified compared with unstressed, infected animals (Ca group). We examined the phenotypic and functional changes of these effector cells recruited at the site of C. albicans infection. The recruitment of peritoneal cells (PC) was markedly reduced in Ca-S animals and the arrival of Mphi and PMN was selectively diminished after CVS exposure. The integrin CD11b/CD18, implicated in migration and C. albicans phagocytosis, was downregulated in Mphi of Ca-S animals. The activation markers CD54 and MHC-II were upregulated in Mphi after fungal contact. The expression of CD54 was only changed in Ca-S rats. Finally, TNF-alpha production was reduced in PC of Ca-S animals, suggesting an impairment of functional activity. Taken together, the phenotypic and functional changes detected in effector cells may account for the decreased resistance to candidiasis seen in conjunction with CVS. The changes seen also expand our knowledge of the role of Mphi in the control of C. albicans dissemination.

The relationship of some negative events and psychological factors to periodontal disease in an adult Swedish population 50 to 80 years of age

BACKGROUND

Clinical observations and epidemiological studies suggest that experiences of negative life events, especially those manifested as depression, may contribute to an increased susceptibility to periodontal disease.

OBJECTIVE

In the present study, the prevalence of some negative life events and psychological factors and their relation to periodontal disease were investigated. The sample consisted of individuals 50-80 years of age from an extensive cross-sectional epidemiological study performed in 1993 in the city of Jönköping, Sweden.

METHOD

298 dentate individuals from the Jönköping study were randomly selected. Clinical and radiographic examinations included registration of the number of existing teeth, plaque index, gingival index, pocket depth, and alveolar bone loss. In addition, a questionnaire about socioeconomic status, life events, and psychological and stress-related factors was used.

RESULTS

The results revealed that, in addition to the well-documented periodontal disease risk factors such as increased age, oral hygiene status, and smoking, the loss of a spouse (being a widow or widower) and the personality trait of exercising extreme external control were also associated with severe periodontal disease.

CONCLUSION

The findings support recent studies suggesting that traumatic life events such as the loss of a spouse may increase the risk for periodontal disease. Above all, the present results indicate that an individual's ability to cope with stressful stimuli (coping behavior), as measured by the beliefs of locus of control of reinforcements may play a role in the progression of periodontal disease.

Psychoneuroimmunology of depression: clinical implications

Psychoneuroimmunology is a field that investigates the interactions between the brain and the immune system. One important goal of this field of research is to translate basic research in order to understand how behavior affects health and resistance to disease in humans. This review evaluates the impact of depression on morbidity and mortality risk and asks whether neuroimmune mechanisms contribute to this association. Examples are drawn from three diseases: cardiovascular disease, infectious disease, and rheumatoid arthritis. Finally, the potential for biobehavioral interventions to impact psychological adaptation and the course of immune related disease is discussed.

Toxoplasma gondii: cold stress-induced modulation of antibody responses

Physical or psychological stressors have been shown to have significant consequences in the immune function and the outcome of disease in human and animal models. Recent work has demonstrated that products released during stress, such as glucocorticoids and catecholamines, can profoundly influence the in vitro growth of pathogens by modulating immune responses. The present study examined the effects of a physical stressor (cold stress) on antigens of Toxoplasma gondii that elicits an antibody-mediated immune response during the acute and chronic phases of infection. Sera obtained from different groups of mice subjected to cold stress during the acute and chronic phases of T. gondii infection were used to measure the levels of antibodies and to localize by Western blot the dominant antigens eliciting IgG and IgM antibody responses. Serum antibodies collected from stressed and infected mice recognized antigens different from those recognized by infected mice without stress. During the acute phase, a stronger IgM antibody response against antigens of 30, 42, 54, and 60 kDa was detected in stressed animals at 3 weeks postinfection. In addition, a 5-kDa antigen was specifically detected in mice subjected to stress during the acute and chronic phases of infection. Levels of specific IgG were increased in infected and in infected and stressed animals that underwent stress in the chronic phase. IgM production did not increase following cold stress in the chronic phase. These results suggest that the strong antibody response in stressed animals is associated with longer parasite persistence in circulation. Stress modulated not only the host immune response but also the ability of parasite antigens to elicit specific antibody responses by the host.

Chronic fatigue syndrome: neurological findings may be related to blood--brain barrier permeability

Despite volumes of international research, the etiology of chronic fatigue syndrome (CFS) remains elusive. There is, however, considerable evidence that CFS is a disorder involving the central nervous system (CNS). It is our hypothesis that altered permeability of the blood-brain barrier (BBB) may contribute to ongoing signs and symptoms found in CFS. To support this hypothesis we have examined agents that can increase the blood-brain barrier permeability (BBBP) and those that may be involved in CFS. The factors which can compromise the normal BBBP in CFS include viruses, cytokines, 5-hydroxytryptamine, peroxynitrite, nitric oxide, stress, glutathione depletion, essential fatty acid deficiency, and N-methyl-D-aspartate overactivity. It is possible that breakdown of normal BBBP leads to CNS cellular dysfunction and disruptions of neuronal transmission in CFS. Abnormal changes in BBBP have been linked to a number of disorders involving the CNS; based on review of the literature we conclude that the BBB integrity in CFS warrants investigation.

In vivo immunomodulation by peripheral adrenergic and cholinergic agonists/antagonists in rat and mouse models

Our work is devoted to defining relationships between the immune system and the adrenergic and cholinergic systems in vivo. In the rat model, we have shown that the cells of different immune compartments express the genes of a defined set of adrenergic/cholinergic receptors, and it was shown that lymphocytes are a site of non-neuronal production of norepinephrine and acetylcholine. Furthermore, using implantable slow-release tablets containing adrenergic or cholinergic agonists/antagonists, distinct and partly opposite effects were observed on peripheral immune functions. Concerning sympathetic immunoregulation, our data--in contrast to those of other studies--suggest that an enhanced adrenergic tonus leads to immunosuppression primarily via alpha 2-receptor-mediated mechanisms. Beta-blockade strongly enhances this effect, most likely by inhibition of pineal melatonin synthesis. In recent experiments on the kinetics it was found that the continuous alpha-adrenergic treatment entails a strong suppression of cellular responsiveness during the first few hours, which is increasingly followed by a general loss of lymphocytes in blood and lymphoid organs most likely due to enhanced apoptosis. More recently, we have extended our studies to the mouse model. First data obtained with RNAse protection assays suggest a biphasic effect on the gene expression of several cytokines in spleen cells due to adrenergic in vivo treatment.

Dexamethasone promotes type 2 cytokine production primarily through inhibition of type 1 cytokines

Glucocorticoids, at concentrations mimicking stress-physiologic plasma levels, cause an in vitro shift in the type 1/type 2 cytokine balance of human peripheral blood mononuclear cells (PBMC) toward a predominant type 2 response. The mechanisms of these immune alterations are currently unknown but may involve modulation of key cytokines known to regulate the type 1/type 2 cytokine balance. Therefore, we sought to determine the role of cytokines previously reported to regulate the type 1/type 2 cytokine balance, including interleukin-12 (IL-12), interferon-gamma (IFN-gamma, IL-10, IL-4, and IL-13, in the glucocorticoid-mediated human type 1/type 2 cytokine alterations. Human PBMC were stimulated in vitro with tetanus toxoid in the presence of 10(-8) M dexamethasone (DEX). Cultures were supplemented with recombinant human (rHuIL-12), rHuIFN-gamma, or neutralizing monoclonal antibodies (mAb) against IL-4, IL-10, or IL-13. DEX decreased IFN-gamma production and increased IL-4 and IL-10 production by tetanus-stimulated PBMC. The addition of either recombinant IL-12p70 or IFN-gamma abrogated the DEX-mediated decrease in IFN-gamma and increase in IL-4 production. Neutralization of IL-4 activity partially abrogated the DEX-induced alterations in IFN-gamma and IL-4, but not IL-10, production. Neutralization of IL-10 or IL-13 had no effect on the Dex-mediated type 1/type 2 cytokine alterations. Therefore, the DEX-mediated type 1/type 2 cytokine alterations in tetanus-stimulated PBMC are primarily the result of downregulation of type 1 cytokines, subsequently permitting the production of type 2 cytokines.

Timing within the menstrual cycle, sex, and the use of oral contraceptives determine adrenergic suppression of NK cell activity

Physiological responses that involve adrenergic mechanisms, such as stress-induced changes in cardiovascular indices, were reported to fluctuate along the menstrual cycle. Metastatic development following surgery was also reported to vary according to the menstrual phase during which a primary breast tumour was removed. Natural killer (NK) cells are believed to play an important role in controlling metastases. Our recent studies in rats demonstrated that adrenergic suppression of NK activity and of resistance to metastasis is more profound during oestrous phases characterized by high levels of oestradiol. In the current study in humans, we examined the in vitro impact of a beta-adrenergic agonist, metaproterenol (MP), on NK activity, comparing blood drawn from (a) women tested at 3-4 different phases of their menstrual cycle (n = 10), (b) women using oral contraceptives (OC) (n = 10), and (c) men (n = 7). NK activity in each blood sample was assessed in the presence of 5 different concentrations of MP (10(-8)M to 10(-6)M), and in its absence (baseline). The results indicated marked group differences in the magnitude of NK suppression by MP: EC(50)was 2. 6-fold lower in the luteal phase compared to the follicular phase, and 1.8-fold lower in OC users compared to men, who were least susceptible to the effects of MP. No significant group differences or menstrual effects in baseline levels of NK activity were evident. These findings provide the first empirical evidence for menstrual regulation of adrenergic impact on cellular immune competence. Relevance of these findings to the relation between the timing of breast cancer excision within the menstrual cycle and survival rates is discussed.

Immunity in barren and enriched housed pigs differing in baseline cortisol concentration

It was shown in a recent study [De Jong IC, Prelle IT, Van de Burgwal JA, Lambooij E, Korte SM, Blokhuis HJ, Koolhaas JM. Effects of environmental enrichment on behavioral responses to novelty, learning and memory and the circadian rhythm in cortisol in growing pigs. Physiol Behav, in press.] that barren housed pigs (small pens, no substrate) have a blunted circadian rhythm of salivary cortisol as compared to enriched housed pigs (large pens with daily fresh bedding). In the light period, enriched housed pigs showed significantly higher concentrations of cortisol in saliva than barren housed pigs, whereas in the dark period, cortisol concentrations were low in both enriched and barren housed pigs. In the present study, the immunological consequences of the difference in baseline salivary cortisol concentration in the light period were evaluated. It appeared that leukocyte and lymphocyte distributions, and in vitro lymphocyte proliferation following ConcanavalineA (ConA) stimulation in the assay using purified lymphocytes were not affected. However, barren and enriched housed pigs did show a different proliferation response to ConA in the whole blood assay. At day 2 of culture, proliferation was higher in barren housed pigs than in enriched housed pigs, whereas at day 4 of culture, proliferation was higher in enriched housed pigs than in barren housed pigs. Lymphocyte proliferation at day 2 of culture in the whole blood assay correlated negatively with plasma cortisol levels, which might thus explain the higher proliferation in barren housed pigs at day 2 of culture. The in vivo humoral and cellular (delayed type hypersensitivity, DTH) immune response to KLH was not affected by housing conditions. We conclude that, although baseline salivary cortisol concentrations differ between enriched and barren housed pigs, immune function appears to be relatively unaffected.

On the development of psychoneuroimmunology

Psychoneuroimmunology, the study of interactions among behavioral, neural and endocrine, and immune processes, coalesced as an interdisciplinary field of study in the late 1970s. Some of the early research that was critical in establishing neuroanatomical, neurochemical and neuroendocrine pathways and functional relationships between the brain and the immune system is outlined here. These and subsequent studies have led to the general acknowledgment that the nervous and immune systems are components of an integrated system of adaptive processes, and that immunoregulatory processes can no longer be studied as the independent activity of an autonomous immune system. This paradigm shift in the study of immunoregulatory processes and the elaboration of the mechanisms underlying behaviorally induced alterations of immune function promise a better understanding and a new appreciation of the multi-determined etiology of pathophysiological states.

Multipoint linkage analysis of a candidate gene locus in rheumatoid arthritis demonstrates significant evidence of linkage and association with the corticotropin-releasing hormone genomic region

OBJECTIVE

Rheumatoid arthritis (RA) is the most common disabling autoimmune disease, affecting approximately 1% of the population. The disease etiology is unknown, but it involves inflammation and immune dysregulation and is influenced by genetic variation at both HLA and other, as-yet-unidentified genetic loci. Corticotropin-releasing hormone (CRH; or corticotropin-releasing factor), a primary regulator of the hypothalamic-pituitary-adrenal axis and a key element in the response to stress and inflammation, is a strong candidate gene for RA. We examined the role of DNA variation across the region containing this gene in multicase families with RA.

METHODS

We genotyped fluorescently labeled simple tandem repeat genetic markers from chromosome 8q13 in 295 families with multiple cases of RA. Singlepoint and multipoint nonparametric linkage analysis and association analysis using transmission disequilibrium testing (TDT) were also used.

RESULTS

Single-point linkage analysis using a microsatellite within 30 kb of the CRH locus (CRH.PCR at position 8q13) showed a significant excess of allele sharing in 295 United Kingdom RA families with at least 2 affected members (MapMaker/Sibs logarithm of odds [LOD] 1.4; P = 5.5x10(-3); mean identity by descent [ibd] sharing 55.9%). To provide a more detailed linkage map, a multipoint analysis was conducted with an additional 7 dinucleotide microsatellite markers (average heterozygosity 0.75) flanking the CRH locus. Significant linkage was detected over a 22-cM region between D8S285 and D8S530, with the maximum singlepoint LOD score of 1.77 at D8S1723 (MapMaker/Sibs P = 2.2x10(-3); mean ibd sharing 59.3%). Multipoint analysis showed strongest evidence for linkage at the same marker (multipoint LOD 1.78, P = 2.1x10(-3), mean ibd sharing 55.8%). TDT analysis showed significant association at the CRH locus (P = 2.6x10(-3)). CRH has a sibling relative risk of 1.14, and contributes <10% to the sibling relative risk of RA.

CONCLUSION

With the exception of HLA, this is the strongest evidence yet of a genetic locus that is both linked to and associated with RA, and provides an avenue for further genetic characterization and potentially novel therapeutic intervention.

Social isolation may influence responsiveness to infection with bovine herpesvirus 1 in veal calves

An experiment was performed to develop a model to study the impact of stress on responsiveness to infection with bovine herpesvirus 1 (BHV1) in veal calves. Social isolation after previous group-housing was used as a putatively stressful treatment. Group-housed specific pathogen-free veal calves (n=8) were experimentally infected with BHV1 at the age of 12 weeks. Half of the calves were socially isolated at the time of infection. Clinical, virological and serological responses to BHV1, and adreno-cortical reactivity to exogenous ACTH were examined. In comparison with group-housed calves, calves socially isolated at the time of infection showed a diminished clinical and fever response, and delayed viral excretion after primary infection with BHV1. Four weeks after social isolation, basal cortisol levels before, and the integrated cortisol response after administration of a low dose of ACTH, were significantly depressed in socially isolated calves. The results suggest that social isolation in veal calves influences the response to an experimental BHV1 infection. A possible mechanism is discussed.

Norepinephrine stimulates in vitro growth but does not increase pathogenicity of Salmonella choleraesuis in an in vivo model

Norepinephrine stimulates growth of Escherichia coli, Yersinia enterocolitica, and Pseudomonas aeruginosa in serum-supplemented media, and in vivo increases in norepinephrine may be important in the pathogenesis of sepsis by gram-negative bacteria. Because salmonellosis often is associated with stress, the effects of norepinephrine on in vitro growth, and in vivo pathogenicity of the swine pathogen Salmonella choleraesuis were investigated. When RPMI 1640 with and without pig serum was inoculated with fewer than 100 S. choleraesuis/ml and incubated overnight, bacterial numbers were 10(4) to 10(6) lower in RPMI containing serum. Norepinephrine restored bacterial growth in RPMI with serum to normal levels, but it did not increase growth in serum-free RPMI. Similar results were obtained with SAPI, a nutrient-poor medium previously used to study the effect of norepinephrine on growth of gram-negative bacteria. Conditioned media were produced by growing S. choleraesuis in RPMI containing serum with and without norepinephrine and filter sterilizing. Conditioned medium produced with norepinephrine stimulated growth of S. choleraesuis but not E. coli, whereas conditioned medium produced without norepinephrine stimulated growth of both bacteria. To determine the in vivo effects of norepinephrine, rats were implanted with tablets that secrete norepinephrine for 20 to 24 hours or with identical tablets without norepinephrine and infected intraperitoneally with graded doses of S. choleraesuis. The LD-50 of S. choleraesuis was the same in both groups, and norepinephrine did not affect the carrier rate at 30 days after infection. We concluded that although norepinephrine stimulates in vitro growth of S. choleraesuis in serum-based media, the increase in norepinephrine levels in the present in vivo system was probably not sufficient to influence the pathogenesis of S. choleraesuis infection.

Experimental stress suppresses recruitment of macrophages but enhanced their P. gingivalis LPS-stimulated secretion of nitric oxide

BACKGROUND

Epidemiological studies have suggested that stress can alter the onset and progression of periodontal disease. However, the mechanisms involved are not clear. The present study was designed to examine whether the functional response of mouse macrophages stimulated by Porphyromonas gingivalis lipopolysaccharide (LPS) is affected by experimental stress, and to investigate the role of corticosterone (CS) in the stress-related effects.

METHODS

Two models of stress were used: emotional (isolation) and physical (cold). We measured thioglycollate-induced macrophage recruitment in vivo, and LPS-induced nitric oxide (NO) secretion by the macrophages in vitro. Two groups of mice were exposed to the stress conditions: isolation or cold. A third group was injected daily with CS, and a fourth group was used as a control (no stress). After 3 days of stress conditions, thioglycollate was injected into the peritoneal cavity. Four days later, peritoneal macrophages were isolated, counted, and cultured. The secretion of NO by the cultured cells was evaluated with and without P. gingivalis LPS stimulation.

RESULTS

The number of cells in the peritoneal lavage of stressed mice was significantly reduced in comparison to macrophages isolated from non-stressed animals. The number of macrophages from CS-treated mice did not differ from controls. NO secretion from unstimulated macrophages did not differ between the stressed and control groups. Stimulation of the macrophages with P. gingivalis LPS significantly enhanced NO secretion by macrophages from the control and stressed animals, but not by the CS-treated group. NO levels secreted by P. gingivalis-stimulated cells from the two stressed groups were significantly higher than the levels secreted by controls, and the isolation group released significantly higher levels than the cold group. Stimulation of the macrophages with P. gingivalis LPS and interferon (IFN)-gamma resulted in enhanced NO secretion in the 4 groups compared to LPS alone, with no significant differences between the groups.

CONCLUSIONS

The results suggest that experimental stress modulates the response of macrophages to inflammatory stimulants, and that CS is not the sole mediator involved. The presence of IFN-gamma in the culture may mask the functional differences induced by stress. The stress-induced upregulation of NO secretion might be involved in the accelerated periodontal destruction in stressed subjects.

Immune deviation following stress odor exposure: role of endogenous opioids

Olfactory cues can alter immune function. BALB/c mice exposed to odors produced by footshock stressed donor mice have increased antibody responses and increased splenic interleukin (IL)-4 production following immunization relative to recipients of odors from unstressed animals. Here we document that exposure to stress odors results in analgesia that is blocked by the non-selective opioid receptor antagonist naltrexone. The stress odor-induced increase in antigen-driven IL-4 and antibody is also blocked by oral administration of naltrexone. Thus, we provide evidence that immune deviation can occur following a psychosocial stressor, and that the deviation appears to be mediated by endogenous opioid production.

Immunological markers of frequently recurrent genital herpes simplex virus and their response to hypnotherapy: a pilot study

Patients were recruited for hypnotherapy from a clinic for patients with frequently recurrent genital herpes simplex virus (rgHSV). Psychological and immunological parameters were measured 6 weeks prior to hypnotherapy and 6 weeks afterwards, during which time each patient kept a diary of symptoms of rgHSV. Following hypnotherapy there was a significant overall reduction in the number of reported episodes of rgHSV, accompanied by an increase in the numbers of CD3 and CD8 lymphocytes, which may represent a non specific effect of hypnosis. The improvers showed significant rises in natural killer (NK) cell counts, HSV specific lymphokine activated killer (LAK) activity, and reduced levels of anxiety when compared to non-improvers. NK cell numbers and HSV specific LAK activity may therefore be important in the reduction in rgHSV following hypnotherapy.

[Psychoimmunology: a questionable model?]

INTRODUCTION

The concept of "psychoimmunology" that had long been supported by clinical observation and common sense, has acquired a sound scientific basis in the last two decades. The discovery of neuro-mediators and cytokines and their receptors shared by the central nervous system and the immune system has prompted research work using reliable methodologies to study the relationship between a 'hard' scientific field, such as immunology, and a 'soft' one, such as the behavioral sciences.

CURRENT KNOWLEDGE AND KEY POINTS

The complexity of the studies on stress and immunity lies upon the choice of immunological measurements and the development of reproducible stress protocols. Models of stress in experimental animals may address acute versus chronic stress, and individual versus social stress. In humans, typical situations such as academic exams, and care given to patients with dementia, for instance, have been chosen to study large groups of subjects. The development of self-questionnaires for a reliable evaluation of stress and its consequences has led to more accurate measurements of psychosocial events. In animals, acute stress usually drives the immune response towards a Th2, grossly 'immunosuppressive,' profile. In humans, acute stress associates an endocrine response (characterized by glucocorticoid secretion and hyperprolectinemia) with an immunosuppression. Chronic stress is more likely to induce a range of effects, depending on the capacity of the subject to cope with stress, and on his/her social environment. Among the numerous mediators of the hypothalamo-pituitary cascade, Corticotropin Releasing Hormone is a key factor in the stress-immunity relationship. Several studies in humans have demonstrated the influence of stress on the susceptibility to infections (including HIV infection) and on survival in malignant diseases. In autoimmune diseases, a high prevalence of depression, as well as a particular sensitivity to stressful events, seem to modify the course of conditions such as systemic lupus erythematosus, rhumatoid arthritis or Sjögren's disease. The relationship between stress and diseases is based on the pathogenic model which involves the following chain of events: stressor, reaction to stress, neuro-endocrine changes, abnormalities of the immune response, and occurrence (or aggravation) of a disease. The evolution from health to disease could be associated, at least partially, with a 'passive' immunosuppressive mode of response, mediated by the pituitary-adrenal axis, typically the opposite of an 'active,' immunostimulant mode of response, mediated by adrenergic stimulation.

FUTURE PROSPECTS AND PROJECTS

Concept-related problems still remain to be solved: adaptation to stress ('coping'), is both genetically and socially mediated; the significance and interpretation of stress-related abnormalities and their precise involvement in the pathogenesis of diseases may be ambiguous. However, available epidemiological and pathophysiological evidence is currently sufficient to allow physicians in their everyday practice to take stress and depression into account in order to markedly improve the prognosis of many diseases related to immune responses. Prospective studies of neuropsychological intervention, using either pharmacologic or behavioral approaches, should be made to provide the necessary rational to a psychoimmunological management of patients.

Immune correlates of depression

The relation of depression to immunological assays is complex and variable. However, meta-analyses have demonstrated that depressed subjects are likely to show changes in several immune assays. Depressed subjects are likely to have changes in major immune cell classes with an increase in total white blood cell counts and a relative increase in numbers of neutrophils. However, the relative number of lymphocytes is likely to be reduced in depressed subjects. Depression also appears to be associated with increases in at least one measure of immune activation, although further investigations are clearly needed to replicate these interesting observations. Finally, depression is reliably associated with a suppression of mitogen-induced lymphocyte proliferation and with a reduction of NK activity. Despite the heterogeneity of findings, the effect sizes in the relationship between depression and lymphocyte proliferation and NK activity are large as compared to those observed in other areas of psychological and medical research. Several moderating factors may explain and account for the heterogeneity that has been found in the depression-immune results. Future immunologic studies in depressed subjects are needed to clarify the effects of gender and reproductive hormones on the relation between depression and immunity. Severity of melancholic symptoms and sleep disturbance appear to moderate the immune changes in depression but the biological mechanisms that account for the link between these neurovegetative symptoms and depression are not yet known. Finally, assessment of co-morbidity in depressed subjects deserves an increased focus. Data generated from our laboratory clearly show that assessment of alcohol- and tobacco dependence is critical in the interpretation of immune changes in depressed subjects. The clinical significance of changes in immune responses in depressed subjects remains an unanswered question. Studies that use immune measures with disease specific endpoints, as has been recently conducted in the study of VZV immune responses, would help identify the possible link between depression, immune system alterations, and health outcomes.

Effects of social conflict on immune responses and E. coli growth within closed chambers in mice

Social conflict has been shown to affect the neuroendocrine stress response in rodents. The current study was designed to characterize the effects of social conflict on leukocyte subset distribution and function as well as in vivo bacterial growth. Male DBA/2 mice implanted or not implanted with a closed chamber containing Escherichia coli were repeatedly challenged by temporary placement in the territory of a dominant CF-1 mouse five times a day for 2 consecutive days. Nonstressed animals were similarly handled, but were not exposed to social conflict. Effects on immune responses and E. coli growth were analyzed 13 h after the last social conflict session. Social conflict alone was associated with an increase in plasma corticosterone concentration and decreases in thymocyte numbers and splenocyte ability to proliferate in vitro in the presence of lipopolysaccharide (p < 0.05). After social conflict, immature CD4+CD8+ thymocytes decreased, whereas mature T cells increased (p < 0.05). In the presence of E. coli, social conflict induced a significant increase in plasma concentration of interleukin-1beta, and a decrease in the number of thymocytes and the percentage of CD4+CD8+ T cells in the thymus (p < 0.05). In addition to the lymphocyte subpopulation changes observed with social conflict alone, the proportion of CD3+ and major histocompatibility complex (MHC) class II IAd+ cells were significantly higher in stressed mice implanted with a closed chamber containing E. coli (p < 0.05). Social conflict tended to favor E. coli growth in the closed chamber, indicating possible direct bacterial-neuroendocrine hormone interactions. Taken together, these results suggest that stress may modulate the host immune response by altering both bacterial growth and resistance to infection.

Chiropractic management of a patient with myasthenia gravis and vertebral subluxations

OBJECTIVE

The chiropractic management of a patient with myasthenia gravis and vertebral subluxation is described. We discuss the pathophysiology, clinical features, and treatment of patients with these diseases.

CLINICAL FEATURES

The 63-year-old male patient suffered from complaints associated with the disease myasthenia gravis along with signs of vertebral subluxation. The patient had an initial complaint of dysphagia. In addition, the patient experienced swelling of the tongue, nausea, digestive problems, weakness in the eye muscles, difficulty breathing, myopia, diplopia, and headaches. Balance and coordination problems resulted in walking difficulties.

INTERVENTION AND OUTCOME

Contact specific, high-velocity, low-amplitude adjustments were applied to sites of patient subluxation. Myasthenia gravis is no longer debilitating to the patient; he is medication free and has resumed a "normal life."

CONCLUSION

The clinical aspects of the disease, including the possible role of chiropractic intervention in the treatment of patients suffering from myasthenia gravis, are also discussed. This case study encourages further investigation into the holistic approach to patient management by chiropractors vis-a-vis specific adjustments of vertebral subluxation.

A single social defeat transiently suppresses the anti-viral immune response in mice

Most of the studies dealing with effects of stress on anti-viral immunity have been carried out with stressors that are of long duration and that bear little relationship to the nature of the species. In this paper, we investigated the effect of a stressor mimicking real-life situations more closely, being social defeat of male mice, on anti-viral immunity. A single social defeat was applied at 3 or 6 days after inoculation with pseudorabies virus, a herpes virus. It appeared that lymph node cellularity, virus specific IL-2 and IFN-gamma production and lymphocyte proliferation were suppressed at 1 day after defeat, but these parameters restored to control values quickly thereafter. We conclude that the stress of a single social defeat evokes a transient immune suppression, which might have consequences if a pathogenic or lethal virus is involved.

Reactivation of tuberculosis is associated with a shift from type 1 to type 2 cytokines

The pattern of cytokines produced by T cells from mice with latent tuberculosis and during reactivation of tuberculosis was determined. A type 1 cytokine pattern was observed in T cells isolated from the lung of mice with latent disease. Reactivation of mycobacterial growth, by activation of the hypothalamic-pituitary-adrenal (HPA) axis, resulted in a shift from a type 1 to a type 2 cytokine pattern in both CD4 and CD8 T cells. Classification of the T cells based on their differential expression of CD45 and CD44 showed that the phenotypically different populations of CD4 and CD8 cells exhibited a type 1 cytokine pattern at latency and that reactivation of latent tuberculosis was associated with a shift in cytokines produced by these populations to a type 2 cytokine response. Control of mycobacterial growth resulted in a return to the type 1 cytokine pattern found during latent disease.

The Effect of Stress on the Inflammatory Response toPorphyromonas gingivalisin a Mouse Subcutaneous Chamber Model

BACKGROUND

The impact of emotional stress on the outcome of infectious diseases was studied in animal models and humans, but data related to the effect of stress on periodontal infection are limited. Using the subcutaneous chamber model in mice, the present study was carried out to investigate the effect of stress on the host response to Porphyromonas gingivalis.

METHODS

Mice with subcutaneous chambers (2 per animal) were divided into 4 treatment groups: cold-stress; isolation-stress; corticosterone (CS)-injected; and controls. On the third day of stress conditions, heat-killed P. gingivalis were injected into the chambers. The chambers were sampled 1 and 5 days later and analyzed for leukocyte number, tumor necrosis factor (TNF)-alpha levels, and interferon (IFN)-gamma levels.

RESULTS

Injection of P. gingivalis induced the migration of leukocytes into the chambers and increased the intrachamber levels of IFN-gamma and TNF-alpha. There were no significant differences in cell number and IFN-gamma levels between the different treatment groups, but the levels of TNF-alpha were significantly lower in the isolation-stress and cold-stress groups compared to control animals. CS-injected animals were not different from controls. In addition, the levels of TNF-alpha in the stressed animals were lower on the fifth day post-injection than on the first day, but not in the CS and control group.

CONCLUSIONS

The results suggest that the levels of TNF-alpha induced by P. gingivalis in the infection site are downregulated in stressed animals, and CS is not the sole mediator responsible. The stress-induced reduction in TNF-alpha levels might have an impact on the pathogenesis of periodontal disease in humans experiencing emotional stress.

Restraint stress-induced immunosuppression by inhibiting leukocyte migration and Th1 cytokine expression during the intraperitoneal infection of Listeria monocytogenes

In this study, a murine model of Listeria monocytogenes infection was used to investigate effects of restraint stress (RST) on host defense. We observed that the L. monocytogenes infection as well as RST induced an elevation of endogenous corticosterone (CORT) levels and RST synergistically enhanced endogenous CORT levels during the listerial infection. RST suppressed the migration of leukocytes including macrophages, neutrophils, NK cells and lymphocytes into the peritoneal cavities after the intraperitoneal inoculation of L. monocytogenes. RST also suppressed the increase of the surface MHC class II antigen expression in both peritoneal macrophages and B cells during the listerial infection. Interestingly, gene expression of iNOS, MCP-1 (JE) and Th1-type cytokines including IFN-gamma and IL-12 was down-regulated but Th2-type cytokine (IL-4 and IL-6) gene expression in the PEC was rather up-regulated on day 7 after infection, indicating that Th2-type immune response is more resistant to the elevated endogenous CORT levels than Th1-type response. Treatment of mice with RU486, a glucocorticoid receptor antagonist, restored the immune responses suppressed by RST to their normal levels in the infected mice, suggesting that the RST-induced elevation of endogenous corticosterone levels is mainly responsible for the induction of the immunosuppressive events during L. monocytogenes infection.

Glucocorticoid-induced type 1/type 2 cytokine alterations in humans: a model for stress-related immune dysfunction

Increased psychologic and physiologic stressors can have profound effects on the immune system. Previously believed to be immunosuppressive, there is mounting evidence that stress may actually induce a shift in the type 1/type 2 cytokine balance toward a type 2 cytokine response. Cortisol is elevated in response to stress and has been reported to alter cytokine production in murine and human peripheral blood mononuclear cells (PBMC). The current investigation examined the effects of dexamethasone (DEX) mimicking basal, stress, and supraphysiologic levels of cortisol on production of interferon-gamma (IFN-gamma) (type-1), interleukin (IL)-12p40 (type 1), IL-10 (type 2), and IL-4 (type 2) by human PBMC. Both supraphysiologic and stress levels of DEX decreased production of type 1 cytokines and either increased or maintained production of type 2 cytokines PBMC stimulated with phytohemagglutinin (PHA), immobilized anti-CD3, lipopolysaccharide (LPS) or tetanus. Although preincubation with DEX was sufficient to induce a type 2 switch in short-term mitogen cultures, PBMC cultures for extended periods of time required DEX at the initiation and throughout the duration of culture. Mifepristone, a glucocorticoid receptor antagonist, blocked the DEX-induced shift in the type 1/type 2 cytokine balance. These data demonstrated the ability of the glucocorticoid dexamethasone, to induce a shift in the type 1/type 2 cytokine balance toward a type 2 cytokine response and simulate the type 1/type 2 cytokine alterations observed in in vivo stress models. This model will allow detailed investigation of the cellular and molecular mechanisms of stress-induced immune alterations in humans.

An unusual manifestation of encephalitozoonosis in chinchilla rabbits

This disease occurred in 6 rabbits in which leukemic changes after infection with the bovine leukemia virus were being studied.

Stress-related modulation of central nervous system immunity in a murine model of herpes simplex encephalitis

This study assesses the immunomodulatory effects of stress on the pathogenesis of herpes simplex encephalitis (HSE) in a mouse model. Physical restraint served as the stressor and HSE developed subsequent to HSV-1 inoculation into the tongues of subject animals. Clinical data showed that stressed mice lost more weight and had greater mortality rates than unrestrained animals during the course of infection. Histologic tissue sections demonstrated a stress-related reduction of the cellular inflammatory response in the central nervous system (CNS). This model may be useful to further investigate the mechanisms of stress-related immunosuppression in the CNS.