Cytokine production and lymphocyte transformation during stress

The relationship of depression and stressors to immunological assays: a meta-analytic review

This is a broad meta-analysis of the relations of both depression and stressors to immunological assays. The number of study samples (greater than 180) and measures (greater than 40) is much more extensive than any so far. Analyses are done by both fixed and random effects. By a fixed-effects analysis, both major depression and naturally occurring acute stressors are associated with (1) an overall leukocytosis, (2) mild reductions in absolute NK-cell counts and relative T-cell proportions, (3) marginal increases in CD4/CD8 ratios, and (4) moderate decreases in T- and NK-cell function. However, the degree of heterogeneity of the studies' results raises questions about their robustness. Therefore, we also did the first random effects analysis to estimate what is likely to appear in future studies. For depression, the analysis showed the immunological correlates included (1) an overall leukocytosis, manifesting as a relative neutrophilia and lymphoenia; (2) increased CD4/CD8 ratios; (3) increased circulating haptoglobin, PGE(2), and IL-6 levels; (4) reduced NK-cell cytotoxicity; and (5) reduced lymphocyte proliferative response to mitogen. For stressors, the random effects analysis showed that future studies are likely to find the following effects: (1) an overall leukocytosis, manifesting as an absolute lymphocytosis; (2) alterations in cytotoxic lymphocyte levels, CD4/CD8 ratios, and natural killer cell cytotoxicity with the direction of change depending on the chronicity of the stressor; (3) a relative reduction of T-cell levels; (3) increased EBV antibody titers; (4) reduced lymphocyte proliferative response and proportion of IL-2r bearing cells following mitogenic stimulation; and (5) increased leukocyte adhesiveness. The random-effects analysis revealed that for both major depression and naturally occurring stressors the following effects are shared: leukocytosis, increased CD4/CD8 ratios, reduced proliferative response to mitogen, and reduced NK cell cytotoxicity. The implications for these findings for disease susceptibility and the pathophysiology of these conditions is discussed.

Immune responsiveness following academic stress in first-year medical students

Many studies illustrate that physical or psychologic stressors can alter human immune function, which might predispose one to an increased susceptibility to infections. In the present study, we monitored immune responsiveness in 16 first-year medical students (age 23.8 +/- 2.2 years) during the first examination session. Baseline blood samples were collected 30 days prior to the first examination session. Subsequently, subjects were randomly assigned to two groups, and blood samples were collected at 24 h (POST24h) or 48 h (POST48h) after an examination. The percentage of CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD3(+)CD45RO(+), CD3(+)CD45RA(+), CD3(-)CD16(+)56(+), CD19(+), and CD14(+) cells in whole blood was examined to determine changes in circulating immune cell populations. Activation of peripheral blood mononuclear cells (PBMC) with a mixture of phorbol myristate acetate (PMA) and ionomycin or lipopolysaccharide (LPS) for 4 h was used to assess the distribution of interleukin-2 (IL-2)-secreting or interferon-gamma (IFN-gamma)-secreting CD4(+) and CD8(+) cells, as well as IL-1alpha-secreting CD14(+) cells. Activation with a combination of phytohemagglutinin (PHA) and LPS was used to assess secretion of IL-2, IFN-gamma, IL-4, IL-10, soluble IL-2 receptor-alpha (sIL-2Ralpha), IL-1beta, and IL-1R antagonist (IL-1Ra) by PBMC in 48-h cell culture. A significantly higher level of total T cells was found at POST24h, and CD14(+) was elevated at both POST24h and POST48h. The percentage of CD4(+) and CD8(+) cells significantly declined at POST24 and POST48h. A significant elevation in the percentage of memory T cells was observed at POST48h, whereas the percentage of naive T cells was elevated at POST24h and POST48h. These changes were accompanied by a significant decline in percentage of natural killer (NK) cells 24 h after the examination. The percentage of IL-2-producing CD4(+) and CD8(+) cells was significantly lower at POST24h, and the percentage of CD8(+)IFN-gamma(+) cells significantly declined at POST48h. The percentage of CD14(+)IL-1alpha(+) significantly declined at both POST24 and POST48h. A significant decrease was observed in IL-2 secretion 24 h after the examinations, and the secretion of IL-4 and IL-1beta significantly declined at POST48h. No changes in IFN-gamma, IL-10, sIL-2Ralpha, and IL-1Ra secretion were observed. We conclude that the stress outcomes of academic examinations in first-year medical students can significantly alter immune cell distribution and in vitro production and secretion of specific cytokines.

Th1 and Th2 cytokine responses to academic stress

Predominant Th2 profiles are associated with the worsening of asthma, and stress is speculated to induce a Th2 profile. The goals of this study were to examine the responses of the cytokines Th1 (IFN-gamma and IL-2) and Th2 (IL-4, IL-5, and IL-6) to a stressor and to look at the relationships between cytokine and psychological responses. Twenty-four students with and without a history of asthma completed questionnaires and gave blood samples during nonexam and exam periods. Cytokines were measured by ELISA from supernatants of stimulated mononuclear cells (MNC) and whole blood. During examinations, there were a significant decrease in IL-2 and a significant increase in IL-6 production (both cultures) and a significant decrease in IFN-gamma production (MNC cultures). Baseline IL-2 levels showed significant negative correlations with several stress and mood scores. Findings of this study indicate a down-regulation of Th1 and a selective up-regulation of Th2 cytokines during a stressful exposure.

Stress-induced changes in skin barrier function in healthy women

Despite clear exacerbation of several skin disorders by stress, the effect of psychologic or exertional stress on human skin has not been well studied. We investigated the effect of three different stressors, psychologic interview stress, sleep deprivation, and exercise, on several dermatologic measures: transepidermal water loss, recovery of skin barrier function after tape stripping, and stratum corneum water content (skin conductance). We simultaneously measured the effects of stress on plasma levels of several stress-response hormones and cytokines, natural killer cell activity, and absolute numbers of peripheral blood leukocytes. Twenty-five women participated in a laboratory psychologic interview stress, 11 women participated in one night of sleep deprivation, and 10 women participated in a 3 d exercise protocol. The interview stress caused a delay in the recovery of skin barrier function, as well as increases in plasma cortisol, norepinephrine, interleukin-1beta and interleukin-10, tumor necrosis factor-alpha, and an increase in circulating natural killer cell activity and natural killer cell number. Sleep deprivation also decreased skin barrier function recovery and increased plasma interleukin-1beta, tumor necrosis factor-alpha, and natural killer cell activity. The exercise stress did not affect skin barrier function recovery, but caused an increase in natural killer cell activity and circulating numbers of both cytolytic T lymphocytes and helper T cells. In addition, cytokine responses to the interview stress were inversely correlated with changes in barrier function recovery. These results suggest that acute psychosocial and sleep deprivation stress disrupts skin barrier function homeostasis in women, and that this disruption may be related to stress-induced changes in cytokine secretion.

Hypnosis as a modulator of cellular immune dysregulation during acute stress

To assess the influence of a hypnotic intervention on cellular immune function during a commonplace stressful event, the authors selected 33 medical and dental students on the basis of hypnotic susceptibility. Initial blood samples were obtained during a lower stress period, and a second sample was drawn 3 days before the first major exam of the term. Half of the participants were randomly assigned to hypnotic-relaxation training in the interval between samples. Participants in the hypnotic group were, on average, protected from the stress-related decrements that were observed in control participants' proliferative responses to 2 mitogens, percentages of CD3+ and CD4+ T-lymphocytes, and interleukin 1 production by peripheral blood leukocytes. More frequent hypnotic-relaxation practice was associated with higher percentages of CD3+ and CD4+ T-lymphocytes. These data provide encouraging evidence that interventions may reduce the immunological dysregulation associated with acute stressors.

How does stress affect you? An overview of stress, immunity, depression and disease

OBJECTIVE

Stress is a term that has become synonymous with modern life. This review aims to appraise the evidence linking stress with disease with particular reference to the major causes of morbidity and mortality in the Western World, cardiovascular disease, cancer, and depression. Changes in immune parameters in stressful situations were reviewed as a possible pathophysiological mechanism for such effects.

METHOD

A Medline search was carried out for the period 1996-2000 to identify recent findings in this field using the terms "stress", "disease", "immune system". Relevant references that were found in all identified publications were also followed up.

RESULTS

There is evidence to link stress with the onset of major depression and with a poorer prognosis in cardiovascular disease and cancer. Few small studies suggest that stress management strategies may help to improve survival. Chronic stress appears to result in suppression of the immune response, whereas immune activation and suppression have been associated with acute stress. Inflammatory cytokines, soluble mediators of the immune response, can result in symptoms of depression.

CONCLUSION

Further prospective epidemiologically based studies are needed to clarify the role of stress on disease onset, course, and prognosis. Stress management strategies, aimed at prolonging survival in patients with cardiovascular disease, cancer, and possibly other chronic illnesses, are an exciting area of further research. Immune system changes may account for the relationship between stress and disease. We propose the "stress, cytokine, depression" model as a biological pathway to explain the link between stressful life events and depression.

Circulating dopamine level, in lung carcinoma patients, inhibits proliferation and cytotoxicity of CD4+ and CD8+ T cells by D1 dopamine receptors: an in vitro analysis

Besides cardiovascular and renal functions, the role of dopamine in periphery as an endogenous regulator of immune functions is in the limelight. In human malignancy, depression of T cell functions is known. Interestingly, recent evidences indicate significant elevation of plasma dopamine in malignancy due to stress of the disease process. Therefore, this study evaluates whether this increased plasma dopamine exerts any influence on the proliferation and cytotoxicity of CD4+ and CD8+ T cells. Patients with lung carcinoma were selected for this study due to the high prevalence rate of this kind of cancer in developing countries and also due to strong positive biochemical and psychological criteria of stress in most of the patients. Results showed significant elevation of plasma dopamine (48.6 +/- 5.1 pg/ml) in lung cancer patients than normal controls (10.2 +/- 0.9 pg/ml). In vitro dopamine concentration, simulating the plasma concentration of the patients, significantly inhibited the proliferation and cytotoxicity of T cells of these patients and also of the normal volunteers, in presence of their respective serum. The mechanism has been attributed to be D1 class of dopamine receptor mediated elevation of intracellular cAMP in these cell populations. The results may be of significance in understanding the role of peripheral dopamine as an immunomodulator in human health and diseases.

Psychological stress may induce increased humoral and decreased cellular immunity

Stress alters immune function and affects different immune cell populations in different ways. The authors examined whether psychological stress has different effects on the production of macrophage, T-helper 1(Th1) cell, and T-helper 2(Th2) cell-derived cytokines. Forty-two college students were recruited and their blood was sampled on the day they were to take a stressful academic examination and again 4 weeks after the examination. The stress from the academic examination significantly increased IL-1 beta, IL-6, and IL-10 and decreased IFN-gamma production. These findings suggest that examination stress may increase Th2 cell-mediated humoral immunity and macrophage activities and may decrease Th1 cell-mediated cellular immunity.

Aberrant nuclear expression of AP-1 and NFkappaB in lymphocytes of women stressed by the experience of breast biopsy

We have investigated the expression of AP-1 and NFkappaB in peripheral blood lymphocytes of women scheduled for breast biopsy. Samples were collected when women were informed of the need for biopsy (prebiopsy, T1, 5-7 days prior to the actual biopsy) and 7-10 days after they learned the result of their biopsy (postbiopsy, T2). At the time of blood collection, psychological stress was evaluated using Speilberger's State Trait Anxiety Inventory (STAI) and the Profile of Mood States (POMS). Women scheduled to undergo breast biopsy reported significant increases in anxiety (STAI) and mood disturbance (POMS). Gel shift mobility assays showed that mitogen stimulated peripheral blood lymphocytes of these women were less capable of the nuclear expression of AP-1 or NFkappaB at T1. Similar assessments, 7-10 days after the women learned of the results of their breast biopsy, showed these same women to have a marked reduction in anxiety and mood disturbance and an increased nuclear translocation of AP-1 and NFkappaB. These results show a significant decrease in nuclear AP-1 and NFkappaB expression during the period of emotional distress prior to biopsy with a return of nuclear transcription activity to normal levels when distress was relieved. Several studies have correlated increased psychological stress with decreased immune function. The results of this study suggest that psychological stress may mediate immunosuppression by altering the expression of the transcription factors, AP-1 and NFkappaB.

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.

Anticipatory symptoms and anticipatory immune responses in pediatric cancer patients receiving chemotherapy: features of a classically conditioned response?

There is considerable evidence from studies in adult patients that classical conditioning contributes to anticipatory nausea and/or vomiting (ANV) in cancer chemotherapy: The stimuli predicting the infusion serve as conditioned stimuli (CS). When reexposed to the CS, some patients experience ANV prior to infusion onset. In adult patients, anticipatory immunomodulation (AIM) has also been observed. The present study examines whether ANV and AIM occur in pediatric cancer patients and whether they show features of a conditioned response.

METHODS

Nineteen pediatric cancer patients (M = 10.1 years, > 2 previous chemotherapies) were studied over two consecutive cycles (A, B). In both cycles, self-reported symptoms, for example nausea and vomiting, were recorded from two days prior to the onset (Day -2), during infusion, and two days after the end of the infusion (Day +2). In Cycle B, blood was drawn at home at Day -2, and at Day 0 in the hospital prior to infusion onset, thus using a quasi-experimental variation of the CS content of the environment. Immune parameters valid for tumor defense and cytotoxic competence (natural killer cell activity [NKCA], plasma interleukin [IL]-1beta, IL-2, IL-10, interferon [IFN]-gamma, tumor necrosis factor [TNF]-alpha) and cortisol were measured.

RESULTS

ANV was reported by 7 patients in at least one cycle. In Cycle A, ANV was positively associated with emetogenity of chemotherapy. Features of ANV-duration and occurrence-tended to be positively associated with those of posttreatment nausea and vomiting. AN increased as infusion onset time approached. NKCA and IFN-gamma increased from home to hospital, independent from cortisol level. The NKCA increase was predominantly observed in patients with ANV.

CONCLUSIONS

ANV in pediatric patients showed features of a CR. Immune parameters were sensitive to the CS content of the environment, predominantly in patients with ANV. This is consistent with the manifestation of multiple CRs.

Psychoneuroimmunology and cancer: fact or fiction?

There is substantial evidence from both healthy populations as well as individuals with cancer linking psychological stress with immune downregulation. This discussion highlights natural killer (NK) cells, because of the role that they may play in malignant disease. In addition, distress or depression is also associated with two important processes for carcinogenesis: poorer repair of damaged DNA, and alterations in apoptosis. Conversely, the possibility that psychological interventions may enhance immune function and survival among cancer patients clearly merits further exploration, as does the evidence suggesting that social support may be a key psychological mediator. These studies and others suggest that psychological or behavioural factors may influence the incidence or progression of cancer through psychosocial influences on immune function and other physiological pathways.

The measurement of stress-related immune dysfunction in psychoneuroimmunology

In recent years there has been a dramatic increase in research dedicated to the psycho-behavioural modulation of immune function, i.e. the field of Psychoneuroimmunology (PNI). This has led, necessarily, to the use of several in vitro and in vivo techniques in attempts to delineate the relationship between these two phenomena. However, since the field's inception, considerable uncertainty has existed over the significance of the immune outcomes detected and this has been compounded by the equivocal nature of some of the published data. A great deal of this uncertainty could, however, be overcome if a clearer understanding was achieved on the advantages and limitations conferred by the manifold immune assays described in the literature. This would, in turn, encourage their more appropriate use within PNI. Hence, in this review we describe the rationale behind, and offer an evaluation of, some of the more frequently used in vitro and in vivo immunological and virological techniques. We hope that a clear understanding of the rationale behind such assays and their inherent advantages and limitations will inform the discussion of the significance of stress-related immune impairment.

Review of psychosocial stress and asthma: an integrated biopsychosocial approach

Environmental stressors may impact asthma morbidity through neuroimmunological mechanisms which are adversely impacted and/or buffered y social networks, social support, and psychological functioning. In addition, life stress may impact on health beliefs and behaviours that may affect asthma management. Whereas earlier psychosomatic models have supported a role for psychological stress in contributing to variable asthma morbidity among those with existing disease, a growing appreciation of the interactions between behavioural, neural, endocrine, and immune processes suggest a role for these psychosocial factors in the genesis of asthma as well. While a causal link between stress and asthma has not bee established, this review provides a framework in which we can begin to see links between these systems that might provide new insights to guide future explorations. The complexity of these interactions underscore the need for a multidisciplinary approach which combines the idea that the origin of asthma is purely psychogenic in nature with the antithetical consideration that the biological aspects are all important. These distinctions are artificial, and future research that synthesizes biological, psychological, sociocultural, and family parameters is urgently needed to further our understanding of the rising burden of asthma.

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.

Cytokine dysregulation associated with exam stress in healthy medical students

The mechanisms of stress-related immune alterations have not been fully elucidated. Cell-mediated immune responses as well as antibody and certain cytokines are reported as being suppressed during times of high stress. However, the role of suppression vs dysregulation has not been established in human stress models. The effect of exam stress on regulatory cytokines in 16 healthy medical students was assessed by measuring type-1 (IFN-gamma) and type-2 (IL-10) cytokines from 72-h PHA/PMA-stimulated PBMC 4 weeks before and 48 h after exams. Results demonstrated decreased IFN-gamma accompanied by increased IL-10 during exam stress that resulted in a decreased IFN-gamma:IL-10 ratio. There was a significant correlation between the cytokine response to PHA/PMA and number and subjective adjustment to daily hassles. Additionally, students who reported greater levels of loneliness also reported greater numbers of and poorer subjective adjustment to hassles. The differences were consistent in both males and females but did not correlate with AM cortisol levels. Additionally, when individuals were grouped into high vs low preexam hassle levels, the type-1/type-2 shift in the IFN-gamma:IL-10 ratio occurred in the low hassles group only. These data suggest that psychologically stressful situations shift type-1/type-2 cytokine balance toward type-2 and result in an immune dysregulation rather than overall immunosuppression. This may partially explain the increased incidence of type-2-mediated conditions such as increased viral infections, latent viral expression, allergic/asthmatic reactions, and autoimmunity reported during periods of high stress.

Immunosuppressive effect of vestibulo-cerebellar lesion in rats

Kainate lesion of the vestibulo cerebellum induces sympathetic hyperactivity, but the mechanism of immunosuppression observed as a result is not yet clarified. Here we report that vestibulo cerebellum lesioned (VCL) rats have depressed secretion of haematopoietic cytokines (bioimmunomodulator or BIM, a 12.7 kD peptide and thymosin FrV) in tissue cultures of bone marrow and thymus, respectively, compared with controls (P < 0.01). Peripheral blood leukocyte concentration, neutrophil myeloperoxydase response, T-SRBC rosette and antibody titre to sheep red blood cells (SRBC) are also significantly less, compared with control (P < 0.01). Injection of BIM (concentration 0.01 microg/g body weight) in VCL rats corrected the immunodeficiency. Partial restoration of immune competence is observed after injection of thymosin FrV (0.01 microg/g body weight) or after prolonged vestibular stimulation (18 rpm for 15 min/day for 21 days). The results indicate that the vestibular nodule (VN) through autonomic nerves (AN) can modulate the immune function of rats by regulating the secretion of cytokines from bone marrow and thymus.

An immunological model connecting the pathogenesis of stress, depression and carcinoma

Recently there has been considerable conjecture in the literature concerning a possible relationship between stress, depression and bereavement, and carcinoma. We shall propose a causal model in which the relationship between stress, depression and carcinoma is clarified. This relationship is grounded on dysregulation of the inflammatory cytokines in stress and depression. Stress is associated with increased expression of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha), and reduced expression of IL-2, interferon-gamma (IFN-gamma), major histocompatability complex (MHC) class II molecules and natural killer cell activity (NKA). Depression is associated with elevated IFN-gamma and IL-1 beta, downregulated IL-2, and reduced NKA. Most organ-related carcinomas are associated with elevated TNF-alpha, which inhibits the activity of protein tyrosine phosphatase (PTPase), the enzyme that initiates activation of the MHC class I pathway. Sustained elevation of TNF-alpha inhibits the activity of PTPase which results in diminished expression of the MHC class I antigen on the cell surface and thus, malignant cells escape immune surveillance. Therefore, stress and depression can foster tumor progression by means of inhibiting the expression of MHC class I and II molecules and through the reduction of NKA.

Influence of academic examination stress on hematological measurements in subjectively healthy volunteers

Some recent reports showed that a brief exposure to a mental stressor during 3-20 min may induce hematological changes in humans. The aim of the present study was to examine the effects of academic examination stress on erythron variables, such as the number of red blood cells (RBC), hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), mean cell Hb (MCH), mean cell Hb concentration (MCHC), RBC distribution width (RDW), and serum iron and transferrin (Tf). The above variables were determined in 41 students in three conditions, i.e. the stress condition (the day before a difficult oral exam) and two baseline conditions, i.e. a few weeks earlier and later. At the same occasions, subjects completed the Perceived Stress Scale (PSS), the state version of the State-Trait Anxiety Inventory (STAI) and the Profile of Mood States (POMS). Academic examination stress significantly increased Ht, Hb, MCV, MCH and MCHC and significantly decreased RDW. There were significant relationships between the stress-induced changes in the PSS, STAI and POMS scores and those in Ht, Hb, MCV and MCH (allpositive) and RDW (negative). It is concluded that academic examination stress induces significant hematological changes indicative of an increased number of large RBC and increased hemoglobinisation, which cannot be explained by shifts of fluid out of the intravascular space, concentrating non-diffusible blood constituents.

Stressor-induced alteration of cytokine production in multiple sclerosis patients and controls

OBJECTIVE

We administered an acute psychological stressor to multiple sclerosis (MS) patients and normal controls to determine whether differences in subjective and physiological responses to stress may underlie the susceptibility of MS patients to stress-related exacerbations.

METHOD

Twenty-five MS patients (18 female, 7 male) and 25 age- and gender-matched controls participated in the study. They were asked to give a 5-minute videotaped speech defending themselves in a hypothetical scenario in which they were wrongly accused of stealing. Subjective and autonomic responses were monitored, and blood was sampled at baseline, 5, 20, and 60 minutes after the stressor to assess mitogen-stimulated production of interleukin-1beta(IL-1beta), interleukin-4 (IL-4), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma).

RESULTS

MS patients and controls demonstrated similar subjective and physiological responses to the stressor that were independent of gender, mood, and disability status. The macrophage-derived cytokines IL-1beta and TNF-alpha were increased during the stressor, and remained elevated through 60 minutes. Th1 lymphocyte-derived IFN-gamma production also was increased at 5 and 60 minutes relative to baseline; however, there was no change in the Th2 lymphocyte-derived cytokine IL-4.

CONCLUSIONS

These results favor the hypothesis that MS patients do not differ in stress response from normal controls; however, psychological stress may enhance cellular immune responses that would be potentially harmful to MS patients.

Sympathetic activation triggers systemic interleukin-10 release in immunodepression induced by brain injury

The mechanism of immunodepression after brain injury is not yet clear. Here we demonstrate rapid systemic release of the immunoinhibitory cytokine interleukin-10, monocytic deactivation and a high incidence of infection in patients with 'sympathetic storm' due to acute accidental or iatrogenic brain trauma. In vitro studies showed that within minutes catecholamines trigger the secretion of interleukin-10 from unstimulated monocytes through a beta-adrenoreceptor-mediated, cAMP/protein kinase A-dependent pathway. We found that in a rat model of acute brain injury, the beta-receptor antagonist propranolol prevented the increase of interleukin-10 plasma levels. Rapid monocytic interleukin-10 release after sympathetic activation may represent a common pathway for immunodepression induced by stress and injury.

Increase in gingival inflammation under academic stress

Several correlational questionnaire studies have observed a positive relationship between psychological stress and periodontal diseases. This paper analyses the effects of academic stress on periodontal health in a prospective quasi-experimental design. 26 medical students participating in a major exam and the same number of medical students not participating in any exam throughout the study period volunteered for the study. Bleeding on probing was assessed 4 weeks prior to the exam period (baseline) and at the last day of the exam. Severe deterioration in gingival health from baseline to the last exam day were observed more frequently in exam students than in controls (p=0.014). 6 exam students but only 1 control person developed a severe gingivitis at at least one formerly healthy tooth throughout the study period. These results further support the hypothesis that psychological stress is a significant risk factor for periodontal inflammation. Future studies should examine factors mediating this relationship.

Cytokine profiles of stimulated blood lymphocytes in asthmatic and healthy adolescents across the school year

T cell cytokines play an important role in mediating airway inflammation in asthma. The predominance of a Th2 cytokine profile, particularly interleukin (IL)-4 and IL-5, is associated with the pathogenesis and course of asthma. The aim of this study was to test the hypothesis that a stressful life event alters the pattern of cytokine release in asthmatic individuals. Thirteen healthy controls and 21 asthmatic adolescents gave blood samples three times over a semester: midsemester, during the week of final examinations, and 2-3 weeks after examinations. Interferon-gamma (IFN-gamma), IL-2, IL-4, and IL-5 were measured from supernatants of cells stimulated with PHA/PMA for 24 h. Cells from asthmatic subjects released significantly more IL-5 during the examination and postexamination periods, whereas cells from healthy controls released significantly more IL-2 during the midsemester and examination periods, thereby indicating a bias for a Th2-like pattern in asthmatics and a Th1-like pattern in healthy controls. IL-4 and IL-5 production showed a marked decrease during and after examinations in healthy controls, whereas this decline was absent in asthmatics. The ratios of IFN-gamma:IL-4 and IFN-gamma:IL-5 also revealed significant changes in the profile of cytokine release across the semester. These results indicate differential cytokine responses in asthmatics that may become pronounced during periods of cellular activation.

Searching for the biological pathways between stress and health

Population-based, person-specific health surveys, with concomitant biological measures, should provide important information about the processes by which socioeconomic and psychosocial factors embed themselves in human health. Questionnaire responses allow for assessment of the perceived psychosocial environment, but biological measurements will measure the status of the psychoneuroimmunology/ psychoneuroendocrinology (PNI/PNE) pathways and may allow us to identify people who have "adapted" to their stress because of experience, expectations, stoicism, etc. This review sets criteria to evaluate potential physiological markers of chronic stress. Because population health surveys involve a massive number of samples, special consideration must be given to the laboratory analysis method and transportation time of the markers chosen. We reviewed five areas: glycosylated proteins, the immune system, hemostasis peripheral benzodiazepine receptors, and the waist-hip ratio.

Increased production of interleukin-2 (IL-2) but not soluble interleukin-2 receptors (sIL-2R) in unmedicated patients with schizophrenia and schizophreniform disorder

This study investigated immune activation, as measured by production of interleukin-2 (IL-2) and soluble interleukin-2 receptors (sIL-2R) from stimulated lymphocytes, in schizophrenia and schizophreniform disorder. The study included 13 neuroleptic-free patients, 13 medicated patients and 13 age- and sex-matched control subjects. Production of IL-2 and sIL-2R by peripheral blood mononuclear cells (PBMCs) was measured after in vitro stimulation with phytohaemagglutinin (PHA). Patients' symptoms were rated on the Scales for Assessment of Positive (SAPS) and Negative Symptoms (SANS) and the Brief Psychiatric Rating Scale (BPRS). IL-2 production by stimulated lymphocytes was significantly elevated in neuroleptic-free patients compared with both medicated patients and control subjects. IL-2 production was inversely correlated with the SAPS subscales of bizarre behaviour and formal thought disorder. The pattern of increased IL-2 production is in contrast to previous findings in patients with schizophrenia. Significant associations with clinical rating scores suggest that IL-2 production may vary in different biological subgroups of schizophrenia and schizophreniform disorder.

Preanalytical factors and the measurement of cytokines in human subjects

Cytokines are widely measured in research. However, cytokine analyses are influenced by a myriad of factors. For instance, a delay in the separation of plasma from cells may lead to a 50% decrease in the concentration of tumor necrosis factor in plasma. Another example is the secretion of interleukin-1 beta in women which can be twice as high during the follicular phase as in the luteal phase. The factors influencing the outcome of these tests can be divided into in vivo preanalytical factors (e.g., aging, chronobiological rhythms, diet, etc), in vitro preanalytical factors (e.g., specimen collection, equipment, transport, storage, etc), and analytical factors. To improve the value of the cytokine tests, factors strongly influencing the results have to be controlled. This can be done by using standardized assays and specimen collection procedures. In general, sufficient attention is not given to the preanalytical factors, especially in the measurement of cytokines. This article reviews the preanalytical factors which may influence the outcome of these tests in human subjects.

The effects of acute psychologic stress on cellular adhesion molecules

Cellular adhesion molecules, or CAMs, constitute a family of cell-surface receptors responsible for mediating interactions among leukocytes, platelets, and vascular endothelium. This pilot study (N = 22 healthy men and women) examined the effects of a 6-minute speaking stressor on several CAMs, including L-selectin, ICAM-1, and the integrins. The psychologic stressor caused a significant decrease in L-selectin (p = 0.04). Significant task by gender interactions indicated that during stress women increased whereas men decreased in 3 markers of the integrin family, LFA-1, LFA-2, and LFA-3 (all p < 0.05). There was no significant task effect on ICAM-1 nor group differences in state anger or anxiety ratings following the task. Across all subjects, the changes (task minus baseline) in LFA-1 and LFA-2 were negatively correlated with the subjects' age (r(=) = -0.49, p = 0.02 and r(=)-0.53, p = 0.01, respectively), indicating that older subjects showed less change in these markers than did younger subjects. These preliminary findings suggest that the immune activation that accompanies acute psychologic stress may be sufficient to alter the expression of certain cellular adhesion molecules. Further study should be directed towards determining whether cellular adhesion molecule expression is altered equally across various leukocyte subsets or is restricted to specific cell types.

Psychosocial and immune effects of self-hypnosis training for stress management throughout the first semester of medical school

This study was a 19-week prospective conducted to determine the effectiveness of a self-hypnosis/relaxation intervention to relieve symptoms of psychological distress and moderate immune system reactivity to examination stress in 35 first-year medical students. Twenty-one subjects were randomly selected for training in the use of self-hypnosis as a coping skill and were encouraged to practice regularly and to maintain daily diary records related to mood, sleep, physical symptoms, and frequency of relaxation practice. An additional 14 subjects received no explicit training in stress-reduction strategies, but completed similar daily diaries. Self-report psychosocial and symptom measures, as well as blood draws, were obtained at four time points: orientation, late semester, examination period, and postsemester recovery. It was found that significant increases in stress and fatigue occurred during the examination period, paralleled by increases in counts of B lymphocytes and activated T lymphocytes, PHA-induced and PWM-induced blastogenesis, and natural killer cell (NK) cytotoxicity. No immune decreases were observed. Subjects in the self-hypnosis condition reported significantly less distress and anxiety than their nonintervention counterparts, but the two groups did not differ with respect to immune function. Nevertheless, within the self-hypnosis group, the quality of the exercises (ie, relaxation ratings) predicted both the number of NK cells and NK activity. It was concluded that stress associated with academic demands affects immune function, but immune suppression is not inevitable. Practice of self-hypnosis reduces distress, without differential immune effects. However, individual responses to the self-hypnosis intervention appear to predict immune outcomes.

Psychosocial modulation of cytokine-induced natural killer cell activity in older adults

The objective of this study was to address the cellular and psychological mechanisms underlying previously observed changes in natural killer (NK) cell cytotoxicity associated with chronic stress. We compared 28 current and former spousal caregivers of patients with Alzheimer's disease (AD) and 29 control subjects. NK cells were enriched (E-NK) using a 4-step procedure that resulted in a cell preparation consisting of 88.2% NK cells. These cells were then incubated with either recombinant interferon-gamma (rIFN-gamma) or recombinant interleukin-2 (rIL-2) for 65 hours. Although an average of over 3 years had elapsed since the death of the patient with AD for the former caregivers, current and former caregivers did not differ in the E-NK cell responses to rIFN-gamma and rIL-2. However, the E-NK cell response for the combined caregiver group was significantly suppressed compared with controls, which is consistent with a previous report from our laboratory. Higher E-NK cell responses to each cytokine were associated with heightened levels of positive emotional and tangible social support, independent of levels of depression. Preliminary data suggest that defects of NK cell function in response to rIFN-gamma and rIL-2 as a consequence of caregiver stress may be independent of non-NK cells. Finally, our data are consistent with other studies regarding the role of social support in immune modulation.

Immune system of cold-exposed and cold-adapted humans

The aim of this study was to investigate whether or not the human immune system can be activated by a noninfectious stimulus, thereby improving the physiological status of the individual. The effect of a single cold water immersion (14 degrees C for 1 h) on the immune system of athletic young men, monitored immediately after immersion, was minimal. With the continuation of the cold water immersions (three times a week for a duration of 6 weeks) a small, but significant, increase in the proportions of monocytes, lymphocytes with expressed IL2 receptors (CD25) and in plasma tumour necrosis factor alpha content was induced. An increase in the plasma concentrations of some acute phase proteins, such as haptoglobin and haemopexin, was also observed. After 6 weeks of repeated immersions a trend towards an increase in the plasma concentrations of IL6 and the amount of total T lymphocytes (CD3), T helper cells (CD4), T suppressor cells (CD8), activated T and B lymphocytes (HLA-DR) and a decrease in the plasma concentration of alpha 1-antitrypsin was observed. Concentrations of IL1 beta, neopterin, C-reactive protein, orosomucoid, ceruloplasmin, macroglobulin, immunoglobulins (IgG, IgM, IgA) and C3, C4 components of the complement, as well as the total number of erythrocytes, leucocytes, granulocytes and neutrophils showed no significant changes after the repeated cold water immersions. It was concluded that the stress-inducing noninfectious stimuli, such as repeated cold water immersions, which increased metabolic rate due to shivering the elevated blood concentrations of catecholamines, activated the immune system to a slight extent. The biological significance of the changes observed remains to be elucidated.

Effects of social reorganization on cellular immunity in male cynomolgus monkeys

Exposure to acute stressors has been shown to impair cellular immunity in human beings and other animal species. Comparatively little is known, however, about the effects of long-term stressors on immune function and how individual behavioral characteristics may mediate differences in immune function and clinical disease susceptibility. To determine the effects of social stress on cellular immunity and reactivation of a latent herpesvirus, 20 Herpes B virus-positive male cynomolgus monkeys were exposed to four periodic reorganizations of social group memberships over 5 months. Observations were made to categorize individuals as high or low in expression of aggressive, fearful, and affiliative behaviors. Complete blood counts, lymphocyte proliferation tests, and natural killer cell cytotoxicity assays were performed immediately before and 4 days after reorganizations. Herpesvirus-specific immunoglobulin G antibody levels were measured, and oral and conjunctival swabs were cultured for virus. Reorganization was associated with increased lymphocyte counts (P = 0.0009) and decreased lymphocyte proliferation in response to phytohemagglutinin (P < 0.005), particularly among monkeys showing high levels of fear (P = 0.0137). High-aggressive monkeys showed lower baseline natural killer cell activity (P = 0.0013) and higher lymphocyte counts (P = 0.013) than low-aggressive monkeys. Herpesvirus antibody titers decreased over time (P < 0.004) and no positive virus cultures were obtained. Measures of cellular immunity and behavior were unrelated to virus-specific antibody titers. These results suggest that repeated exposure to a social stressor alters several measures of cellular immunity, and that some of these changes may be predicted by individual differences in agonistic behavior. In contrast to human studies, the results suggest that some psychological stressors may not cause reactivation of a common herpesvirus in this species. © 1996 Wiley-Liss, Inc.

Cytokine production and lymphocyte subpopulations in aged humans. An assessment during nocturnal sleep

The view of a general impairment of immune functions associated with aging has been challenged by recent studies including a more detailed evaluation of various cytokines and lymphocyte subsets. In the present human study, effects of age on the production of cytokines by T cells and monocytes were assessed, together with age-dependent changes in subset populations of mononuclear cells (MNC). Blood was collected every 30 min during nocturnal sleep in 16 aged (mean: 79.6 +/- 7.5 years) and in 16 young controls (mean: 24.6 +/- 3.1 years). Nocturnal sleep was chosen as a well-defined period within the 24-h cycle with minimal exogenous influences. The in vitro production of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) was measured after mitogen stimulation with lipopolisaccharide from E. coli (LPS). Production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) was measured after stimulation with phytohemagglutinin (PHA). Regarding MNC subsets, monocytes, lymphocytes, CD3+, CD4+, CD8+, HLA-DR, CD16+, CD25+, and CD19+ were determined. Advanced age was associated with a decreased number of T cells (CD3+) and decreases in the major T cell subsets (CD4+, CD8+, P < 0.001). Production of IL-2 was not affected. However, production of IFN-gamma tended to be enhanced, and numbers of activated T cells (HLA-DR/CD3+), natural killer cells (CD16+), and T cells expressing IL-2 receptors (CD25+/CD3+) were markedly increased in the aged. While monocyte counts were unchanged in the elderly production of IL-1 beta and TNF-alpha mainly derived from these cells, was enhanced (p < 0.05). Results indicate a state of enhanced responsiveness of the T cell compartment and of monocytes in aged which may compensate for the substantial decrease in T cells.

Effects of sleep on the production of cytokines in humans

The restorative functions of sleep may affect immunologic functioning. The present study examined the effects of sleep on stimulated cytokine release in 13 healthy men. The subjects spent 2 experimental nights in the sleep laboratory. In one condition, lights were turned off at 11:00 PM to enable sleep for 3.5 hours. Thereafter, they stayed awake till 7:00 AM. In the other condition, conversely, subjects stayed awake between 11:00 PM and 3:00 AM. Then, lights were turned off for a 3.5-hour phase of sleep. Blood was sampled every 30 minutes between 11:00 PM and 7:00 AM. Sleep was monitored by polysomnographic recordings. Release of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) was determined after stimulation of mononuclear cells with lipopolysaccharide from Escherichia coli. The release of IL-2 was stimulated with phytohemagglutinin. Compared with wakefulness, after 3 hours of sleep, production of TNF-alpha and IL-1 beta was substantially diminished (p < .01). Production of IL-2 was enhanced during sleep (p < .05), with this effect being limited to the second nocturnal sleep phase after 3:00 AM. Sleep-dependent changes in stimulated cytokine release were independent of changes in plasma cortisol concentrations. These results indicate a specific reducing effect of sleep (vs. wakefulness) on cytokine production by monocytes (TNF-alpha and IL-1 beta). The rather slow development of the effects calls for further studies to establish the exact time course of the influence of sleep on cytokine production.

Influence of pain stimulation on interleukin-2 production in mice

We previously demonstrated that plaque-forming cell (PFC) production in the spleen of mice immunized with sheep red blood cells (SRBC) was enhanced by pain stimulation. This phenomenon was due to activation of antigen nonspecific L3T4-/Lyt-2- T lymphocytes (double-negative T cells) by the beta-adrenergic action of endogenous catecholamines released from the adrenal gland after pain stimulation. Further study also demonstrated that interleukin-2 (IL-2) production of spleen cells was enhanced in mice by pain stimulation. In this study spleen cells of BALB/c mice were cultured with Con A and SRBC, respectively, and the IL-2 level was measured by incorporation of 3H-thymidine into CTLL-2 cells during culture for 24 hours. Interleukin-2 production of spleen cells from mice given pain stimulation was significantly increased compared with spleen cells of normal mice. The IL-2 production of spleen cells of normal mice was also markedly enhanced by the mixed culture with spleen cells from pain-stimulated mice. Enhancement of IL-2 production in the spleen cells of mice given pain stimulation did not occur with anti-Thy-1.2 antibody and complement treatment, but production was maintained by treatment with anti-L3T4 antibody and complement. These data suggest that the enhanced production of IL-2 in mice given pain stimulation resulted from the activation of L3T4- T cells by endogenous catecholamines released from the adrenal gland after pain stimulation. It can be assumed that activated L3T4- T cells interact with antigen-specific L3T4+ T cells and lead to enhanced IL-2 production.

Plasma interleukin-1 beta concentrations in panic disorder

Plasma interleukin-1 beta (IL-1 beta) concentrations were measured in 10 outpatients with panic disorder before and on days 30 and 32 of treatment with alprazolam (2-2.5 mg/day). IL-1 beta concentrations were found to be significantly higher in patients than in control subjects both before and during therapy. Thus, IL-1 beta levels may be a marker of panic disorder that is not related to the current level of symptomatology.