Immunosuppressive Effects Of Stress Research Articles

Stressing Out about Cancer Immunotherapy

Stress has long been suspected to negatively influence cancer mortality, yet the molecular mechanisms responsible for this effect have only recently been identified. A new study identifies a stress-induced response in dendritic cells-the activation of the glucocorticoid-inducible transcriptional regulator TSC22D3-as a potent, immunosuppressive effect of stress on cancer.

English

The effect of nickel on hematological parameters and behaviour in Cyprinus carpioafter a 96 h exposure to nickel test was investigated. Cyprinus carpio fingerlings were obtained from local fish hatchery. Morphometric characteristics of experimental fish were recorded. Fish of both sexes were stocked without discrimination. The fish were exposed to different concentrations (0, 6, 9, 12, 15 and 18 mg/l) of nickel sulphate using standard screening procedure. The mortality rate of the experimental fish was increased with increase in concentration of nickel. The 96 h median lethal concentration (96 h LC50) was 12.44 mg Ni/L using the logarithmic method with dose-mortality regression line y = 188.224x – 86.52. The dissolved oxygen concentration decreased with increase in the level of Ni. All the blood parameters (erythrocyte, leucocytes, hematocrit and hemoglobin count) decreased with increasing dose of nickel and become significantly lower (P < 0.05) at higher concentration when compared with the control. Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were also lowered with concentration of toxicant when compared with the control. The results of the present study showed that a short-term exposures to high levels of nickel induced stress reactions in C. carpio. Some adaptive changes were observed; preparing the organism to an increased energy expense, whereas other changes showed a considerable immunosuppressive effect of stress. It was concluded that changes observed indicate that hematological parameters can be used as an indicator of Ni stress in C. carpio.   Key words:  Cyprinus carpio, nickel, bioaccumulation, mortality, haematology, behaviour

Toxic Stress of Nickel on African Catfish, <italic>Clarias gariepinus</italic> Fingerlings

Toxic stress in Clarias gariepinusafter a 96-hr exposure to nickel using the seismic bioassay test was investigated. The experimental fish used were Clarias gariepinus fingerlings. The fish were exposed to different concentrations (0, 4, 6,8,10 and 12mg/l) of nickel sulphate after a rangefinding test using a screening procedure. The mortality rate increased with increased concentration of toxicants. The 96-hr median lethal concentration (96-hr LC50) was 8.87mg Ni/L using the logarithmic method with dose-mortality regression line y = 174.74x � 97.711. The dissolved oxygen decreased at higher levels of toxicants. The obtained data showed that a short-term exposures to high levels of nickel induced stress reactions in C.gariepinus. Some adaptive changes prevailed, preparing the organism to an increased energy expense, while other changes indicated a considerable immunosuppressive effect of stress. Thus, the short term exposure induced persistent stress on the fish which may render them more susceptible to diseases.

Restraint stress decreases virus-induced pro-inflammatory cytokine mRNA expression during acute Theiler's virus infection

Stressful life events have been associated with the onset and/or exacerbation of multiple sclerosis (MS). Our previous studies have indicated that restraint stress (RS) reduces inflammation and virus-induced chemokine expression in the Theiler's virus-induced demyelination (TVID) model of MS. Here we report that RS significantly reduced the virus-induced interferon-γ mRNA levels in the brain. Additionally, mRNA levels of lymphotoxin-β, tumor necrosis factor-α, and interferon-γ in the brain were negatively correlated with viral titers in the brain. These results indicated an immunosuppressive effect of stress during early TVID causing impaired viral clearance, which may be a potential exacerbating factor for later demyelination.

Effects of aged garlic extract (AGE) on the immunosuppressive effects of stress

Effects of aged garlic extract (AGE) on the immunosuppressive effects of stress

Acute stressor exposure facilitates innate immunity more in physically active than in sedentary rats.

Most previous stress-immune research focused on the immunosuppressive effects of stress on acquired immunity. More recently, it has become clear that acute stressor exposure can potentiate innate, as well as suppress acquired, immunity. For example, acute stress improves recovery from bacterial inflammation, a classic in vivo measure of innate immunity. The previous work was done in sedentary organisms. Physical activity status can modulate the impact of stress on immune function. The following studies tested the hypothesis that the effect of stress on inflammation after subcutaneous challenge with bacteria (Escherichia coli) is facilitated by physical activity. The results were that sedentary, stressed rats resolved their inflammation 1-2 days faster and have increased circulating neutrophils compared with their nonstressed, sedentary counterparts. In contrast, physically active, stressed rats resolve their inflammation 3-4 days faster and have increased circulating and inflammatory site neutrophils compared with their nonstressed counterparts. Importantly, the beneficial impact of stress on inflammation recovery and neutrophil migration was greater in the physically active, than sedentary, stressed rats. Thus physical activity status facilitates the positive effect of acute stress on innate immunity.

Restraint stress-induced suppression of major histocompatibility complex class II expression by murine peritoneal macrophages

The macrophage plays a central role in the development of immune response. Macrophages take up and process antigen which is presented to antigen-responsive T lymphoctes in assoication with major histocompatibility complex class II (Ia) glycoproteins. We have investigated the effect of restraint stress on Ia expression by murine peritoneal macrophages. Stress resulted in a suppression of Ia expression which coincided with an increase in plasma corticosterone levels. In vitro exprements indicate that suppression of Ia expression can occur within 2 h after exposure to corticosterone. The suppression of this important aspect of macrophage function by stressors has important implications regarding the possible immunosuppressive effects of stress on the response of lymphocytes to antigens that depend on intact macrophage function.

Effect of Stress and Dietary Fatty Acids on Allograft Survival in the Rat

To determine the immunosuppressive effect of stress and a diet rich on linoleic acid on vascularized organ graft survival in the rat, a series of allogeneic heart and kidney grafts were carried out. Restraint stress resulted in a significant prolongation of the survival time. Although 5 days of postoperative stress gave the best results, 3 h of stress given on the first postoperative day already gave a marked prolongation of the survival time of kidney allografts. The beneficial effect of stress on heart survival was abolished when prior adrenalectomy was carried out. A diet high on polyunsaturated fatty acids gave significant prolongation of the survival times of kidney-grafted rats. A diet hgh on saturated fatty acids did not result in a statistical significant prolongation of the survival time, although the difference with the polyunsaturated fatty acid group was very small and not statistically significant. It was concluded that stress and diets high in certain types of fatty acids depress the immune response in rats, possibly via a mechanism which has some common pathways. The adrenal glands could play an important role in this immune inhibition.