Evidence for a shift in the Th-1 to Th-2 cytokine response associated with chronic stress and aging

BACKGROUND

A number of studies have shown that the chronic stress of caring for persons with dementia can have significant immunological consequences as demonstrated by the down-regulation/dysregulation of the cellular immune response.

METHODS

Utilizing flow cytometry to measure the percentages and absolute numbers of CD-4(+) and CD-8(+) T lymphocytes producing the cytokines indicative of Th-1, Tc1 and Th-2, and Tc2 cells, we compared spousal caregivers and control subjects. The expression of interleukin-2 (IL-2), interferon gamma (IFN-gamma), and interleukin-10 (IL-10) in the cytoplasm of CD-4(+) and CD-8(+) lymphocytes was assessed.

RESULTS

Neither stress nor age was significantly related to the percentage or number of IFNgamma(+)/CD-8(+), IL-2(+)/CD-8(+) cells, or IFNgamma(+), IL-2(+), CD-4(+) cells. However, the percentage of IL-10(+) cells was higher in lymphocytes obtained from caregivers than control subjects. In addition, the significant interaction between stress and aging for IL-10(+)/CD-4(+) and IL-10(+)/CD-8(+) cells demonstrated that the difference between caregivers and control subjects was age dependent; the difference between caregivers and control subjects was substantially larger in younger individuals than in older individuals.

CONCLUSIONS

The data are consistent with previous reports on acute stress and suggest that there may also be a shift from a Th-1 to a Th-2 response associated with a chronic stressor such as caregiving. This shift could have implications for an individual's responses to pathogens.

The effects of an acute psychological stressor on cardiovascular, endocrine, and cellular immune response: a prospective study of individuals high and low in heart rate reactivity

High and low reactors were preselected on the basis of their heart rate reactivity to a speech stressor in a prescreening session. In the main study, subjects were exposed to a mental arithmetic plus noise stressor. Cardiovascular activity was recorded during baseline and stressor, and blood was drawn prior to and following the stressor for endocrine and immune assays. Results revealed that the stressor decreased the blastogenic response to concanavalin A and increased natural killer cell numbers and cytotoxicity, absolute numbers of CD8+ T-lymphocytes, norepinephrine and epinephrine levels, heart rate, and blood pressure responses. In addition, cortisol and natural killer cell cytotoxicity responses to the stressor differentiated individuals high versus low in heart rate reactivity. These results suggest that the interactions among the autonomic nervous system, endocrine system, and immune system are not only amenable to psychophysiological analysis but that such analyses may play an important role in illuminating underlying mechanisms.

Plasma cortisol levels and reactivation of latent Epstein-Barr virus in response to examination stress

In this study, we explored the possibility that glucocorticoid hormones, known to increase under stress, might be one component of the mechanism involved in induction of latent Epstein Barr virus (EBV). We obtained blood samples from 45 male medical students during examinations and approximately 3-4 weeks before the examinations (baseline) and measured antibody titers to EBV and plasma cortisol levels. We found reproducible changes in EBV, virus capsid antigen (VCA) antibody titers, with higher antibody titers observed in the examination blood samples consistent with the reactivation of latent virus. However, we found no evidence that day and night plasma cortisol values across the sampling points changed significantly from baseline to examinations. Therefore, academic stress did not elevate cortisol levels, but increases in EBV VCA antibody titers were still observed. The data suggest in these subjects that other neuropeptides or hormones were involved in the induction of latent EBV.

A biobehavioral model of cancer stress and disease course

Approximately 1 million Americans are diagnosed with cancer each year and must cope with the disease and treatments. Many studies have documented the deteriorations in quality of life that occur. These data suggest that the adjustment process is burdensome and lengthy. There is ample evidence showing that adults experiencing other long-term stressors experience not only high rates of adjustment difficulties (e.g., syndromal depression) but important biologic effects, such as persistent downregulation of elements of the immune system, and adverse health outcomes, such as higher rates of respiratory tract infections. Thus, deteriorations in quality of life with cancer are underscored if they have implications for biological processes, such as the immune system, relating to disease progression and spread. Considering these and other data, a biobehavioral model of adjustment to the stresses of cancer is offered, and mechanisms by which psychological and behavioral responses may influence biological processes and, perhaps, health outcomes are proposed. Finally, strategies for testing the model via experiments testing psychological interventions are offered.

Stress-induced suppression of herpes simplex virus (HSV)-specific cytotoxic T lymphocyte and natural killer cell activity and enhancement of acute pathogenesis following local HSV infection

Stressful events suppress a broad spectrum of both humoral and cellular immunological responses. However, studies of the effects of stress on the development of specific antiviral immune responses have not been reported. We have utilized an established murine model of an acute, local footpad Herpes simplex virus type 1 (HSV-1) infection to study the effect of restraint stress on the generation of HSV-specific cytotoxic T lymphocytes (CTL) and natural killer (NK) cell activity. Lymphoproliferative responses in the popliteal lymph nodes following footpad infection as well as the generation of HSV-specific CTL and NK cell activity were depressed in restrained mice compared to infected, unrestrained controls. Frequency analyses of HSV-specific pre-CTL indicated that suppression of the CTL response occurred early in the sequence of events that precedes the generation of functionally lytic CTL and was not mediated by a diminished IL-2 response. Although restrained mice exhibited fewer lymphocytes in the popliteal lymph nodes, the subset distribution was the same as that in the unrestrained controls. Furthermore, stress-induced immunosuppression resulted in a higher titer of infectious HSV at the site of infection. Overall, these findings provide evidence that physiological changes associated with restraint stress can influence the immune response to a specific viral infection and alter the course of viral pathogenesis.

Immunological consequences of acute and chronic stressors: mediating role of interpersonal relationships

This review presents recent studies examining the relationship between acute and chronic stressors, changes in immune function, and interpersonal relationships. Data are given which document immunosuppressive effects of commonplace, short-term stressors, as well as more prolonged stressors, such as marital disruption and caregiving for a relative with Alzheimer's disease. Immune changes included both quantitative and qualitative changes in immune cells, including changes in herpes virus latency, decreases in the percentages of T-helper lymphocytes and decreases in the numbers and function of natural killer cells. These effects occurred independently of changes in nutrition. Psychological variables, including loneliness, attachment and depression were related to the immune changes. The data are discussed in a framework in which quality interpersonal relationships may serve to attenuate the adverse immunological changes associated with psychological distress, and may have consequences for disease susceptibility and health.

Psychological influences on surgical recovery. Perspectives from psychoneuroimmunology

Greater fear or distress prior to surgery is associated with a slower and more complicated postoperative recovery. Although anxiety presumably interferes with recuperation through both behavioral and physiological mechanisms, the pathways have been unclear. Recent work in psychoneuroimmunology (PNI) has demonstrated that stress delays wound healing. In addition, a second line of research has illustrated the adverse effects of pain on endocrine and immune function. A biobehavioral model is described that is based on these and other data; it suggests a number of routes through which psychological and behavioral responses can influence surgery and post-surgical outcomes. Clinical and research implications are highlighted.

Stress and the transformation of lymphocytes by Epstein-Barr virus

Although various stressors appear to influence herpesvirus infections, the underlying mechanisms have not been studied. A prospective design was used to examine the effects of examination stress and loneliness on the transformation of B lymphocytes in mixed cultures of T and B lymphocytes by Epstein-Barr virus (EBV). Three blood samples were drawn from 42 EBV-seropositive medical students, with the baseline sample taken 1 month before their final examinations, the stress sample drawn on the first day of final examinations, and the third sample taken the first week after their return from summer vacation. A median split on the UCLA Loneliness Scale divided the subjects into high- and low-scoring loneliness groups. There were significant effects for change over trials, with the lowest transformation levels (i.e., more virus required to transform cells) found in the stress sample. There was also a significant main effect for loneliness, in which high loneliness was associated with lower transformation levels. Possible immunological pathways for the observed changes are discussed.

Perceived stress and cellular immunity: when coping counts

This cross-sectional study investigated whether active and avoidance coping methods were differentially related to immune function depending on stress level. Perceived stress and coping method were assessed in 173 healthy older adults and related to the number and percentage of CD3+, CD4+, and CD8+ T lymphocytes as well as the proliferative response of peripheral blood leukocytes to phytohemagluttinin (PHA) and concanavalin A (Con A). Both active and avoidance coping significantly interacted with perceived stress on proliferative responses to both mitogens. Higher levels of active coping were significantly related to a more vigorous proliferative response to PHA and Con A, particularly at high stress levels. At low stress levels, active coping was not significantly related to proliferative responses, whereas avoidance coping was significantly associated with a greater proliferative response to Con A. These results suggest that the relationships between certain coping methods and immune function depend on perceived stress level.

Stress and the memory T-cell response to the Epstein-Barr virus in healthy medical students

This study investigated the memory T-cell proliferative response to several early and late Epstein-Barr virus (EBV) polypeptides. Blood samples were collected twice, 1 month before a 3-day block of examinations and again on the last day of the exam series. Ss were 25 healthy, EBV seropositive medical students. The proliferative response to 5 of the 6 EBV polypeptides significantly decreased during examinations. In addition, Ss high (above the median) in seeking support, as measured by the COPE, had lower proliferative responses to 3 EBV polypeptides (p17, p52/50, and p85), as well as higher levels of antibody to EBV virus capsid antigen. The data provide further evidence that psychological stress can modulate the cellular immune response to latent EBV.

Marital stress: immunologic, neuroendocrine, and autonomic correlates

Ninety newlywed couples (mean age = 25), selected on the basis of extremely stringent mental and physical health criteria, were admitted to a hospital research unit for 24 hours to provide a detailed assessment of conflict-resolution behaviors and changes in autonomic, endocrine, and immune function. Among these newlyweds, negative or hostile behaviors during marital conflict (coded from videotaped interactions) were associated with increased levels of epinephrine, norepinephrine, growth hormone, and ACTH as well as greater immunological change over the subsequent 24 hours. Wives demonstrated greater and more persistent physiological changes related to marital conflict than husbands. To assess the generalizability of these physiological changes, a similar laboratory paradigm was used with 31 older couples (mean age = 67) who had been married an average of 42 years. Consistent with the data from newlyweds, both endocrinological and immunological data showed significant relationships to negative behavior during marital conflict in these older couples. These findings suggest that abrasive marital interactions have important endocrinological and immunological correlates.

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.

Predictors of risk for different stages of adolescent smoking in a biracial sample

This investigation was designed to identify the risk factors associated with different stages of cigarette use in a large biracial adolescent sample. A questionnaire assessing smoking habits and variables thought to be related to smoking was administered to 6,967 7th graders. Analysis revealed that the best predictor of experimentation with cigarettes was the perception that they were easily available. Regular smoking appeared to be heavily influenced by cost. Social influences contributed to both experimental and regular smoking, but the impact of social models varied with ethnicity and gender. Analysis further revealed that weight-related variables were closely tied to regular smoking. Implications of the findings for smoking prevention programs are discussed.

The influence of psychological stress on the immune response to vaccines

We compared virus-specific antibody and T-cell responses to influenza virus vaccination in 32 caregivers of Alzheimer's disease (AD) patients and matched control subjects. Caregivers showed a poorer antibody response and virus-specific T-cell response following vaccination compared to the control subjects as measured by fourfold increases in antibody titers to the vaccine and lower levels of virus-induced IL-2 levels in vitro. We performed a second study in which forty-eight medical students were inoculated with a series of three injections of the hepatitis-B (HEP-B) vaccine to coincide with the third day of three, three-day examination blocks. Twelve of the 48 medical students seroconverted after the first injection; these students were characterized by falling into the lower stressed/lower anxiety group of students. Students who reported greater social support and lower anxiety and stress demonstrated a higher antibody response to the vaccine and a more vigorous T-cell response to HEP-B surface antigen at the end of the third examination experience. The differences in antibody and T-cell responses to HEP-B and influenza virus vaccinations provide a demonstration of how stress may be able to alter both the cellular and humoral immune responses to vaccines and novel pathogens in both younger and older adults.

Influence of academic stress and season on 24-hour mean concentrations of ACTH, cortisol, and beta-endorphin

We investigated the influence of a common stressful event, i.e., academic examinations, on the 24-h mean concentration of adrenocorticotropic hormone (ACTH), cortisol, and/or beta-endorphin. In addition, we evaluated the effect of season on the endocrine response to this stressor. We studied medical students (n = 55), screened for a variety of health and life style factors, from three consecutive medical school classes 1 month before, during, and 2 weeks following examinations. Hourly blood samples were obtained from an indwelling catheter and two serum pools were made (0800-2200h = day and 2300-0700h = night). Examinations produced a significant (p < .001) increase in perceived stress scores. In addition, we found a significant (p < .001) effect of examination stress on the increase in mean daytime but not nocturnal ACTH levels during autumn, but not during the spring. In contrast, the examination stress did not significantly affect day or night mean cortisol levels from baseline to examination week. We further divided the students by whether their perceived stress scores increased during examination week and fell during recovery (Group 1) or whether their perceived stress scores did not follow the expected pattern (Group 2). We found that in the Group 1 students who perceived the most stress, cortisol levels significantly increased (p < .001) from baseline to examination. Therefore, the nature of the stressor and the state of the responder were of equal importance in the observed cortisol response during examinations among these students. Further, academic stress had no significant effect on beta-endorphin levels. Finally, we found that the mean day and night ACTH levels were higher (p < .001) in the spring than in the fall; a seasonal influence on cortisol and beta-endorphin concentrations, however, was not observed. In summary, we have demonstrated that stress associated with the taking of examinations produces a dissociation among mean 24-h levels of ACTH, cortisol, and beta-endorphin. In addition, daytime cortisol levels increased during examinations only in the group of students whose perceived stress scores increased. Further, a seasonal influence on ACTH secretion was suggested by these results with higher levels observed in the spring than in the fall.

The differential impact of training stress and final examination stress on herpesvirus latency at the United States Military Academy at West Point

In this study, we searched for evidence for reactivation of three latent herpesviruses, Epstein-Barr virus (EBV), herpes simplex virus type-1 (HSV-1), and human herpesvirus 6 (HHV-6), in West Point cadets experiencing two different stressors. Blood samples were obtained from cadets before and after a 6-week training period known as "Cadet Basic Training" (CBT), at a baseline prior to final examinations, and then once again during the week of final examinations. Antibody titers to latent HSV-1, EBV, and HHV-6 were determined as a measure of the steady-state expression of latent virus. EBV virus capsid antigen (VCA) IgG antibody titers were unchanged in blood samples obtained prior to and immediately after CBT. However, EBV antibody titers were significantly higher in the blood sample obtained during examination week than in the baseline period before examination; they were also higher than antibody titers before/after CBT. None of the serum samples were positive for EBV VCA IgM antibodies, indicating that the changes in antibody titers to EBV were not associated with recent EBV infections in the class. No significant changes in antibody titers to HSV-1 or HSV-6 were found over the identical time periods, including examination week. Academic stress but not CBT modulated the steady-state expression of latent EBV, resulting in the reactivation of latent virus. The same stressors, however, did not affect the steady-state expression of latent HSV-1 or HSV-6, at least as measured by changes in antibody titers. The data provide additional evidence of the impact of different psychological stressors on the steady-state expression of latent herpesviruses.

Postmenopausal hormone replacement: effects on autonomic, neuroendocrine, and immune reactivity to brief psychological stressors

OBJECTIVE

Postmenopausal status increases some aspects of women's physiological responses to psychological stress; however, the influences of chronic hormone replacement with estrogen and progestogen on these responses are not known. We investigated possible effects of long-term estrogen replacement therapy (ERT), both with and without progestogen, on physiological reactivity to brief laboratory stressors.

METHOD

We studied three groups of postmenopausal women: 16 on estrogen alone, 14 on estrogen and progestogen, and 25 control participants receiving no replacement therapy. Cardiovascular, neuroendocrine, and immune data were collected at baseline and after speech and math tasks.

RESULTS

In all groups, the stressors reduced vagal cardiac control (indexed by respiratory sinus arrhythmia); increased heart rate and plasma epinephrine, adrenocorticotropic hormone, and cortisol levels; and altered T lymphocyte response (measured by mitogen-induced cell proliferation), natural killer cell lysis, and circulating leukocyte subsets. Women on either type of ERT had higher total cortisol levels (reflecting an estrogen effect on cortisol binding globulin) and greater mitogen-induced blastogenesis across measurement periods than controls. They also showed greater vagal withdrawal and less decline in mitogen-stimulated blastogenesis in response to the stressors. Combined estrogen and progestogen was associated with higher epinephrine and lower circulating total lymphocytes, T cells, and CD4+ T cells across measurement periods, and with intermediate levels of vagal withdrawal in response to the stressors.

CONCLUSIONS

Long-term ERT was associated with enhanced parasympathetic responsiveness to stress, suggesting possible reduced demand for potentially detrimental sympathetic activation; and with higher overall levels and smaller stress-induced reductions of mitogen-stimulated blastogenesis, suggesting up-regulated T cell function.

Stress-induced modulation of the primary cellular immune response to herpes simplex virus infection is mediated by both adrenal-dependent and independent mechanisms

A murine model of herpes simplex virus (HSV) infection was used to examine the role of the adrenal gland in restraint stress-induced suppression of viral immunity. Adrenal-dependent mechanisms were important for suppressing the generation of HSV-specific cytotoxic T lymphocytes (CTL) but not the associated diminished lymphadenopathy in response to local HSV infection. While exogenous corticosterone administration alone was unable to suppress lymphadenopathy and CTL generation in adrenalectomized mice, an adrenal-independent mechanism induced by restraint stress functioned in synergy with corticosterone to suppress lymphadenopathy and CTL development. These results suggest that both adrenal-dependent and independent mechanisms contribute to stress-induced modulation of HSV immunity.

Rescue of Epstein-Barr virus from somatic cell hybrids of Burkitt lymphoblastoid cells

A Burkitt lymphoblastoid cell line, P3J-HR-1, was fused and hybridized to a human sternal marrow cell line. The somatic cell hybrids were negative when examined for Epstein-Barr virus (EBV) markers. When the hybrid cells were exposed to 5-iododeoxyuridine, both EBV-specific antigens and virus particles were induced as determined by the immunofluorescence test and by electron microscopy. The data presented suggest that the EBV genome can be transferred from a lymphoblastoid cell to another cell type during cell hybridization, that the EBV genome can persist in the hybrid cells for long periods of time, and that synthesis of the virus can be induced in the heterokaryons.

Host cell regulation of induction of Epstein-Barr virus

When Epstein-Barr virus (EBV) negative cells (Raji) were treated with iododeoxyuridine, only the early antigen (EA) component was induced. There was no significant increase in EBV DNA and no virus particles were observed. Somatic-cell hybrids were prepared from the fusion of Raji and D98 cells (D98/Raji). When these cells were treated with iododeoxyuridine, early antigen EBV DNA, and virus particles were synthesized. These data suggest cellular control over the expression of the EBV genome.

Frequency and levels of antibodies to Epstein-Barr virus-specific DNase are elevated in patients with nasopharyngeal carcinoma

Sera from healthy individuals and patients with infectious mononucleosis, Burkitt lymphoma, nasopharyngeal carcinoma, or other malignancies were examined for their capacity to neutralize Epstein-Barr virus (EBV)-induced DNase activity. Sera were found that neutralized the EBV DNase but not herpes simplex virus type 1 or type 2 DNases, and vice versa. Sera from 46 of the 49 patients with nasopharyngeal carcinoma examined (94%) neutralized > 6 units of EBV DNase per ml of serum. In contrast, only 19% of 47 patients with Burkitt lymphoma, 12% of 183 patient with other malignancies, 4% of 58 patients with infectious mononucleosis, and none of 101 healthy individuals had such levels of neutralizing activity. The neutralizing factor was found in the IgG fraction derived from nasopharyngeal carcinoma sera. There was no correlation between the concentration of these antibodie and the titers of IgG ad IgA antibodies to the EBV capsid antigen, the early antigen complex, or the EBV-associated nuclear antigen.

Anti-Gal(alpha)1-3Gal antibody response to porcine bone marrow in unmodified baboons and baboons conditioned for tolerance induction

BACKGROUND

Mixed lymphohematopoietic chimerism can provide an effective means of inducing longterm immunological tolerance and has been documented in a monkey allograft model. A conditioning regimen including nonmyeloablative or myeloablative irradiation and splenectomy has been used to induce chimerism in a pig-to-primate transplantation model. Since the presence of anti-Gal(alpha)1-3Gal (alphaGal) natural antibodies leads to the hyperacute rejection of pig organs transplanted into primates, extracorporeal immunoaffinity adsorption (EIA) of anti-alphaGal antibodies is also included in the regimen. The effect of the tolerance induction protocol on the anti-alphaGal antibody response has been assessed.

METHODS

Anti-alphaGal antibody was measured after the EIA of plasma through an alphaGal immunoaffinity column in baseline studies involving two unmodified baboons, one splenectomized baboon, and one baboon that received a challenge with porcine bone marrow (BM), and in three groups of baboons (n=2 in each group) that received different conditioning regimens for tolerance induction. Group 1 received a nonmyeloablative conditioning regimen without porcine BM transplantation. Group 2 received nonmyeloablative conditioning with pig BM transplantation and pig cytokine therapy. Group 3 received myeloablative conditioning, an autologous BM transplant (with BM depleted of CD2+ or CD2+/CD20+ cells), and pig BM transplantation.

RESULTS

In the baseline studies, a single EIA of anti-alphaGal antibodies in an unmodified animal initially depleted anti-alphaGal antibody, followed by a mild rebound. Nonmyeloablative conditioning (group 1) in the absence of pig cell exposure reduced the rate of anti-alphaGal antibody return. Pig BM cells markedly stimulated anti-alphaGal antibody production in an unmodified baboon (alphaGal IgM and IgG levels increased 40- and 220-fold, respectively). This response was significantly reduced (to an only 2- to 5.5-fold increase of IgM and IgG) in baboons undergoing nonmyeloablative conditioning (group 2). A myeloablative conditioning regimen (group 3) prevented the antibody response to pig BM, with the reduction in response being greater in the baboon that received autologous BM depleted of both CD2+ and CD20+ cells. No new antibody directed against pig non-aGal antigens was detected in any baboon during the 1 month follow-up period.

CONCLUSIONS

(i) EIA of anti-alphaGal antibody in unmodified baboons results in a transient depletion followed by a mild rebound of antibody; (ii) exposure to pig BM cells results in a substantial increase in anti-alphaGal antibody production; (iii) a nonmyeloablative conditioning regimen reduces the rate of antibody return and (iv) markedly reduces the response to pig BM cells; (v) the anti-alphaGal response is completely suppressed by a myeloablative regimen if CD2+ and CD20+ cells are eliminated from the autologous BM inoculum. Furthermore, (vi) challenge with pig BM cells appears to stimulate only an anti-alphaGal antibody response without the development of other (non-alphaGal) anti-pig antibodies. We conclude that regimens used for T-cell tolerance induction can be beneficial in reducing the anti-alphaGal antibody response to porcine BM.

Effects of stress on methyltransferase synthesis: An important DNA repair enzyme

The enhancement of tumor development following acute stress has been demonstrated in some animal studies. This study was designed to explore mechanisms that would account in part for the relationship between stress and tumor development at the level of DNA repair, using a rat model. Forty-four rats were given the carcinogen dimethylnitrosamine in their drinking water, and half were randomly assigned to a rotational stress condition. The levels of methyltransferase, a DNA repair enzyme induced in response to carcinogen damage, were significantly lower in spleens from the stressed animals. These data suggest that stress may impair DNA repair.