Prenatal stress promotes insulin resistance without inflammation or obesity in C57BL/6J male mice.

During gestation, stress exposure increases the risk of developing cognitive and physiological alterations in either the long or short term. Among them, metabolic alterations have been described. Adipose tissue is responsible for the secretion of several factors involved in controlling body weight and energy expenditure, the regulation of insulin sensitivity, and the development of inflammation, among others. Moreover, the liver regulates glucose homeostasis and lipid metabolism, playing an essential role in developing insulin resistance. In this work, we analyzed if prenatal stress leads to alterations in metabolism and the relationship between these alterations and gene expression in the adipose tissue and the liver. Prenatal stress-exposed animals developed disturbances in the glucose and insulin response curve, showing in both tests higher glycemia than the control group. However, they did not exhibit increased body weight. At the same time, in the adipose tissue, we observed an increase in mRNA expression of Leptin and Resistin and a decrease in Adiponectin. In the liver, we observed a lower mRNA expression of several genes involved in glucose metabolism and fatty acid oxidation, such as Sirt1, Pgc1α, Pparα, among others. In both tissues, we observed a lower expression of inflammatory genes. These results suggest that prenatal stress exposure produces insulin resistance at both physiological and molecular levels without pro-inflammatory signaling or obesity.

Altered interferon-γ expression in lymphocytes as a potential peripheral marker of chronic stress-induced cognitive deficit.

It is known that long-term exposure to stressful situations can produce severe consequences affecting behavioral, endocrine and immunological parameters. We have previously shown that stressed BALB/c mice had poor learning performance, which was reverted by glatiramer acetate treatment through a mechanism that likely involved the regulation of the cytokine balance and adult neurogenesis. In addition, recent results suggest that cytokine and neurotrophin expression in the hippocampus displayed similar tendencies as those in the serum. However, if lymphoid cells could be good candidates as peripheral markers of memory impairment have not yet been investigated. For this purpose, we analyzed the spatial memory and the neutrophin and cytokine mRNA levels in lymph nodes and hippocampus in mice submitted to chronic stress treated or not with glatiramer acetate. Results indicated that there was a correlation between the cytokine and neurotrophin mRNA levels in the hippocampus and in the peripheral lymph nodes, and the cognitive performance in BALB/c mice. In particular, our results suggest that altered IFN-γ levels could be used as peripheral biomarker of cognitive deficit and treatment response.

Immunomodulatory effects of fluoxetine: A new potential pharmacological action for a classic antidepressant drug?

Selective serotonin reuptake inhibitors are frequently used antidepressants. In particular, fluoxetine is usually chosen for the treatment of the symptoms of depression, obsessive-compulsive, panic attack and bulimia nervosa. Antidepressant therapy has been associated with immune dysfunction. However, there is contradictory evidence about the effect of fluoxetine on the immune system. Experimental findings indicate that lymphocytes express the serotonin transporter. Moreover it has been shown that fluoxetine is able to modulate the immune function through a serotonin-dependent pathway and through a novel independent mechanism. In addition, several studies have shown that fluoxetine can alter tumor cell viability. Thus, it was recently demonstrated in vivo that chronic fluoxetine treatment inhibits tumor growth by increasing antitumor T-cell activity. Here we briefly review some of the literature referring to how fluoxetine is able to modify, for better or worse, the functionality of the immune system. These results of our analysis point to the relevance of the novel pharmacological action of this drug as an immunomodulator helping to treat several pathologies in which immune deficiency and/or deregulation is present.

Current Understanding of the Roles of Gut-Brain Axis in the Cognitive Deficits Caused by Perinatal Stress Exposure.

The term 'perinatal environment' refers to the period surrounding birth, which plays a crucial role in brain development. It has been suggested that dynamic communication between the neuro-immune system and gut microbiota is essential in maintaining adequate brain function. This interaction depends on the mother's status during pregnancy and/or the newborn environment. Here, we show experimental and clinical evidence that indicates that the perinatal period is a critical window in which stress-induced immune activation and altered microbiota compositions produce lasting behavioral consequences, although a clear causative relationship has not yet been established. In addition, we discuss potential early treatments for preventing the deleterious effect of perinatal stress exposure. In this sense, early environmental enrichment exposure (including exercise) and melatonin use in the perinatal period could be valuable in improving the negative consequences of early adversities. The evidence presented in this review encourages the realization of studies investigating the beneficial role of melatonin administration and environmental enrichment exposure in mitigating cognitive alteration in offspring under perinatal stress exposure. On the other hand, direct evidence of microbiota restoration as the main mechanism behind the beneficial effects of this treatment has not been fully demonstrated and should be explored in future studies.

Glatiramer acetate reverts stress-induced alterations on adult neurogenesis and behavior. Involvement of Th1/Th2 balance.

Long-term exposure to stressful situations has deleterious effects on adult neurogenesis, behavior, and the immune system. We have previously shown that stressed BALB/c mice show poor learning performance, which correlates with an increase in the T helper 1/T helper 2 (Th1/Th2) cytokine balance. Glatiramer acetate (GA) can stimulate autoreactive T cells. In this work we investigated the effects of GA treatment on BALB/c mice exposed to chronic mild stress (CMS). Stressed mice exhibited a significant decline in their performance in the open field and Y-maze tasks, which was accompanied by a reduction in dentate gyrus neurogenesis and an altered Th1/Th2 balance. Interestingly, after 6 weeks of CMS exposure administration of GA reestablished normal levels of adult neurogenesis, restored the Th1/Th2 balance, and improved learning performance. These results demonstrate that GA treatment can reverse the learning impairment induced by stress through a mechanism that likely involves the regulation of the cytokine balance and adult neurogenesis.

Leukotrienes antagonize the antiproliferative effect of Larrea divaricata Cav. on a lymphoma cell line interfering with cAMP intracellular level and PKC activity.

Larrea divaricata exerts a dual effect on the proliferation of BW5147 cells. The aim of this work was to analyze the effect of leukotrienes on the antiproliferative action of the extract in relation to cyclic adenosine monophosphate production and protein kinase C activation. The extracts induced cyclic adenosine monophosphate and inhibited protein kinase C but induced leukotriene B4 production, which exerted contrary effects. These results suggest the finding of an extract free of compounds, which can increase leukotriene B4 level, in order to obtain a more active extract to be used in the treatment of lymphomas, positively modulated by leukotrienes.

Immunomodulation induced by central nervous system-related peptides as a therapeutic strategy for neurodegenerative disorders.

Neurodegenerative diseases (NDD) are disorders characterized by the progressive loss of neurons affecting motor, sensory, and/or cognitive functions. The incidence of these diseases is increasing and has a great impact due to their high morbidity and mortality. Unfortunately, current therapeutic strategies only temporarily improve the patients' quality of life but are insufficient for completely alleviating the symptoms. An interaction between the immune system and the central nervous system (CNS) is widely associated with neuronal damage in NDD. Usually, immune cell infiltration has been identified with inflammation and is considered harmful to the injured CNS. However, the immune system has a crucial role in the protection and regeneration of the injured CNS. Nowadays, there is a consensus that deregulation of immune homeostasis may represent one of the key initial steps in NDD. Dr. Michal Schwartz originally conceived the concept of "protective autoimmunity" (PA) as a well-controlled peripheral inflammatory reaction after injury, essential for neuroprotection and regeneration. Several studies suggested that immunizing with a weaker version of the neural self-antigen would generate PA without degenerative autoimmunity. The development of CNS-related peptides with immunomodulatory neuroprotective effect led to important research to evaluate their use in chronic and acute NDD. In this review, we refer to the role of PA and the potential applications of active immunization as a therapeutic option for NDD treatment. In particular, we focus on the experimental and clinical promissory findings for CNS-related peptides with beneficial immunomodulatory effects.

Influence of prenatal stress on metabolic abnormalities induced by postnatal intake of a high-fat diet in BALB/c mice.

Prenatal insults during fetal development result in increased likelihood of developing chronic disease. Obesity, the biggest risk factor for the development of metabolic disease, is affected by several genetic and environmental factors. High-fat diet (HFD) consumption is usually linked with the development of obesity. The main goal of this study was to analyze the impact of the exposure to a HFD in prenatally stressed animals. For this purpose, we subjected pregnant BALB/c mice to restraint stress for 2 h a day between gestational day (GD) 14 and GD 21. Prenatally stressed and control offspring of both sexes were postnatally exposed to a HFD for 24 weeks. We found that prenatal stress (PS) per se produced disturbances in males such as increased total blood cholesterol and triglycerides, with a decrease in mRNA expression of sirtuin-1. When these animals were fed a HFD, we observed a rise in glucose and insulin levels and an increase in visceral adipose tissue gene expression of leptin, resistin, and interleukin-1 beta. Although females proved to be more resilient to PS consequences, when they were fed a HFD, they showed significant metabolic impairment. In addition to the changes observed in males, females also presented an increase in body weight and adiposity and a rise in cholesterol levels.

Chronic Stress and Glucocorticoid Receptor Resistance in Asthma.

PURPOSE: Chronic and persistent exposure to negative stress can lead to adverse consequences on health. Particularly, psychosocial factors were found to increase the risk and outcome of respiratory diseases like asthma. Glucocorticoids (GCs) are the most efficient anti-inflammatory therapy for asthma. However, a significant proportion of patients don't respond adequately to GC administration. GC sensitivity is modulated by genetic and acquired disease-related factors. Additionally, it was proposed that endogenous corticosteroids may limit certain actions of synthetic GCs, contributing to insensitivity. Psychological and physiological stresses activate the hypothalamic-pituitary-adrenal axis, increasing cortisol levels. Here, we review the mechanism involved in altered GC sensitivity in asthmatic patients under stressful situations. Strategies for modulation GC sensitivity and improving GC therapy are discussed. METHODS: PubMed was searched for publications on psychological chronic stress and asthma, GC resistance in asthma, biological mechanisms for GC resistance, and drugs for steroid-resistant asthma, including highly potent GCs. FINDINGS: GC resistance in patients with severe disease remains a major clinical problem. In asthma, experimental and clinical evidence suggests that chronic stress induces inflammatory changes, contributing to a worse GC response. GC resistant patients can be treated with other broad-spectrum anti-inflammatory drugs, but these generally have major side effects. Different mechanisms of GC resistance have been described and might be useful for developing new therapeutic strategies against it. Novel drugs, such as highly potent GCs, phosphoinositide 3-kinase-delta inhibitors that reestablish histone deacetylase-2 function, decrease of GC receptor phosphorylation by p38 mitogen-activated protein kinase inhibitors, or phosphatase activators, are currently in clinical development and might be combined with GC therapy in the future. Furthermore, microRNAs (small noncoding RNA molecules) operate as posttranscriptional regulators, providing another level of control of GC receptor levels. Empirical results allow postulating that the detection and study of microRNAs might be a promising approach to better characterize and treat asthmatic patients. IMPLICATIONS: Many molecular and cellular pathobiological mechanisms are responsible of GC resistance. Therefore detecting specific biomarkers to help identify patients who would benefit from new therapies is crucial. Stress consitutes a negative aspect of current lifestyles that increase asthma morbidity and mortality. Adequate stress management could be an important and positive intervention.

Fluoxetine directly counteracts the adverse effects of chronic stress on T cell immunity by compensatory and specific mechanisms.

Chronic stress and depression are widely known to down-regulate the immune system, and several antidepressants can reverse this impairment, with or without effects in normal subjects. Although the central nervous system is undoubtedly involved in these events, some psychotropic drugs can also exert direct effects on lymphoid cells. We have recently shown that the antidepressant fluoxetine enhances T cell proliferation and T(H)1 cytokine production in vivo, without changes on CD4/CD8 subsets. In vitro, a direct action of fluoxetine upon T lymphocyte reactivity by complex mechanisms was also described. In another work, we also found that chronic stress reduces T cell mediated immunity, namely a decrease of T cell response to mitogens, T(H)1 cytokine production and CD4+-but not CD8+--T lymphocytes. Here we investigated the effects of fluoxetine on chronic stress-driven immune system depression. We found that fluoxetine restored T cell proliferation and interleukin-2, interferon-gamma and tumor necrosis factor-alpha production by compensatory mechanisms. In addition, CD4/CD8 ratio was also normalized by antidepressant administration, but this seems to be a non-compensatory effect associated specifically to stress. No changes were observed in other lymphoid cells, i.e. natural killer cells and B lymphocytes. Finally, we observed that fluoxetine is able to reverse T cell reactivity impairment in vitro by a direct action at clinically relevant doses. These results highlight the relevance of pharmacological treatment of stress and depression, and may help to begin elucidating the complex events triggered--directly and/or indirectly--by antidepressants in non-neuronal cell types.

Different effect of chronic stress on learning and memory in BALB/c and C57BL/6 inbred mice: Involvement of hippocampal NO production and PKC activity.

Nitric oxide (NO) has been involved in many pathophysiological brain processes. Recently, we showed that neuronal nitric oxide synthase (nNOS)-mediated decrease in NO production is involved in memory impairment induced by chronic mild stress (CMS) in BALB/c mice. Two genetically different inbred murine strains, C57BL/6 and BALB/c, show distinct behavioral responses, neurodevelopmental and neurochemical parameters. Here, we perform a comparative study on CMS effects upon learning and memory in both strains, analyzing the role of NO production and its regulation by protein kinase C (PKC). Stressed BALB/c, but not C57Bl/6 mice, showed a poor learning performance in both the open field and passive avoidance inhibitory tasks. Also, CMS induced a diminished NO production by nNOS, associated with an increment in gamma and zeta PKC isoenzymes in BALB/c mice. In C57BL/6 mice, CMS had no effect on NO production, but increased delta and decreased betaI PKC isoforms. In vivo administration of a NOS inhibitor induced behavioral alterations in both strains. These results suggest a differential effect of stress, with BALB/c being more vulnerable to stress than C57BL/6 mice. This effect could be related to a differential regulation of NOS and PKC isoenzymes, pointing to an important role of NO in learning and memory.

Immune-endocrine interactions in autoimmune thyroid diseases.

Autoimmune thyroid diseases (AITD) are the most common organ-specific autoimmune disorders affecting approximately 5% of the overall population. An aberrant interaction between abnormal thyrocytes, abnormal antigen-presenting cells and abnormal T cells forms the basis for the atypical autoimmune reaction targeting thyroid antigens. It was proposed that nongenetic (environmental and hormonal) factors play a crucial etiological role in AITD development, through altering immune-endocrine interactions. The most outstanding fact is that in genetically predisposed individuals, the disruption of these neuroendocrine-immune interactions by environmental factors results in thyroid autoimmune dysfunction. These interactions are able to incline the balance between Th1-Th2 immune response toward one side, resulting in a Th1-cell-mediated autoimmune reaction with thyrocyte destruction and hypothyroidism in Hashimoto's thyroiditis but to a hyperreactive Th2-mediated humoral response against TSH receptor with stimulatory antibodies leading to Graves' disease hyperthyroidism. In this review the main mechanisms involved are summarized. In this sense, the participation of stress-mediated activation of the sympathoadrenal system and hypothalamic-pituitary-adrenal axis, the hormonal changes occurring during pregnancy and postpartum acting on antigen-presenting cells and influencing, in this way, the balance of the immune status are shown to participate in AITD etiology. The possibility that altered levels of thyroid hormones during the course of the AITD may alter immune function is also discussed.

Beneficial Effect of Fluoxetine and Sertraline on Chronic Stress-Induced Tumor Growth and Cell Dissemination in a Mouse Model of Lymphoma: Crucial Role of Antitumor Immunity.

Clinical data and experimental studies have suggested a relationship between psychosocial factors and cancer prognosis. Both, stress effects on the immune system and on tumor biology were analyzed independently. However, there are few studies regarding the stress influence on the interplay between the immune system and tumor biology. Moreover, antidepressants have been used in patients with cancer to alleviate mood disorders. Nevertheless, there is contradictory evidence about their action on cancer prognosis. In this context, we investigated the effect of chronic stress on tumor progression taking into account both its influence on the immune system and on tumor biology. Furthermore, we analyzed the action of selective serotonin reuptake inhibitors, fluoxetine and sertraline, in these effects. For this purpose, C57BL/6J mice submitted or not to a chronic stress model and treated or not with fluoxetine or sertraline were subcutaneously inoculated with EL4 cells to develop solid tumors. Our results indicated that chronic stress leads to an increase in both tumor growth and tumor cell dissemination. The analysis of cell cycle regulatory proteins showed that stress induced an increase in the mRNA levels of cyclins A2, D1, and D3 and a decrease in mRNA levels of cell cycle inhibitors p15, p16, p21, p27, stimulating cell cycle progression. Moreover, an augment of mRNA levels of metalloproteases (MMP-2 and MMP-9), a decrease of inhibitors of metalloproteases mRNA levels (TIMP 1, 2, and 3), and an increase in migration ability were found in tumors from stressed animals. In addition, a significant decrease of antitumor immune response in animals under stress was found. Adoptive lymphoid cell transfer experiments indicated that the reduced immune response in stressed animals influenced both the tumor growth and the metastatic capacity of tumor cells. Finally, we found an important beneficious effect of fluoxetine or sertraline treatment on cancer progression. Our results emphasize the crucial role of the immune system in tumor progression under stress situations. Although a direct effect of stress and drug treatment on tumor biology could not be ruled out, the beneficial effect of fluoxetine and sertraline appears to be mainly due to a restoration of antitumor immune response.

Altered nitric oxide synthase and PKC activities in cerebellum of gamma-irradiated neonatal rats.

In this study, we show that one single dose of gamma-irradiation at birth induces an inhibition of the cerebellar calcium dependent nitric oxide synthase (NOS) activity, probably correlated to the motor abnormalities and the disarrangement in the cerebellar cytoarchitecture observed in adult rats. This decrease in calcium dependent NOS activity could be associated with an increased protein kinase C (PKC) activity. PKC inhibition partially restores calcium dependent NOS activity, indicating that PKC activity could be negatively modulating the catalytic activity of calcium dependent NOS. These findings suggest that a decrease in nitric oxide (NO) production and the related increase in PKC activity could be intracellular events that participate in the onset of motor and cerebellar abnormalities induced by postnatal gamma-irradiation at early stages of life.

Involvement of nitric oxide in improving stress-induced behavioural alteration by glatiramer acetate treatment in female BALB/c mice.

RATIONALE: Oxidative stress and neurotrophins are among the most important factors involved in several pathophysiological brain processes. In addition, long-term exposure to stressful situations has deleterious effects on behaviour. We have previously shown that stressed female BALB/c mice show poor learning performance and that this behaviour is reversed by glatiramer acetate (GA) treatment. OBJECTIVES: We investigated the involvement of the hippocampal oxidative status and neurotrophin levels in cognitive deficit and the improvement of this deficit by GA treatment in chronic stressed BALB/c mice. METHODS: Female BALB/c mice were exposed to a chronic mild stress (CMS) model for 9 weeks. During the last 3 weeks of the stress exposure, one group of mice was subcutaneously injected four times with 100 µg GA/mouse. Following this period, behavioural studies were performed. The mice were then sacrificed, and biochemical studies were performed on the hippocampus. RESULTS: The stressed mice exhibited a significant decline in their performance in the open-field and in object-in-place tasks. This decline was accompanied by an increase in reactive oxygen species (ROS) and a decrease in nitric oxide (NO) production by neuronal nitric oxide synthase (nNOS). Neither antioxidant defences nor neurotrophin protein levels were involved in this process. Interestingly, the administration of GA re-established the normal levels of ROS, restored nNOS activity and improved learning performance. CONCLUSIONS: The GA treatment improved learning and memory in female BALB/c mice under chronic stress through a mechanism that involves the regulation of NO production, which in turn modulates the ROS levels.

Acute and chronic stress exert opposing effects on antibody responses associated with changes in stress hormone regulation of T-lymphocyte reactivity.

Here we show that stress exerts a differential effect on T-cell-dependent antibody production. IgG production is augmented after acute stress and impaired in a chronic situation. We found catecholamines and corticosterone levels were increased in acute situations although they were not modified after prolonged stress conditions. However, lymphocyte sensitivity to corticosterone and catecholamines was altered under stress conditions. These results point out the role of the adrenal's hormones as mediators of the differential effects of stress on the immune response providing the basis for a functional significance of stress hormone receptors on lymphocytes.

Altered lymphocyte catecholamine reactivity in mice subjected to chronic mild stress.

There is considerable evidence that the sympathetic nervous system influences the immune response via activation and modulation of beta(2)-adrenergic receptors (beta(2)R). Furthermore, it has been suggested that stress has effects on the sympathetic nervous system. In the present study, we analyzed the influence of catecholamines on the reactivity of lymphocytes from mice exposed to a chronic mild stress (CMS) model of depression (CMS-animals). The effects of the CMS treatment on catecholamine and corticosterone levels and on beta(2)R lymphoid expression were also assessed. For this purpose, animals were subjected to CMS for 8 weeks. Results showed that catecholamines (epinephrine and norepinephrine) exert an inhibitory effect on mitogen-induced normal T-cell proliferation and a stimulatory effect on normal B-cell proliferation in response to selective B lymphocyte mitogens. Specific beta- and beta(2)-antagonists abolished these effects. Lymphocytes from mice subjected to CMS had an increased response to catecholamine-mediated inhibition or enhancement of proliferation in T and B cells, respectively. Moreover, a significant increase in beta(2)R density was observed in animals under CMS compared to normal animals. This was accompanied by an increment in cyclic AMP production after beta-adrenergic stimulation. On the other hand, neither catecholamine levels, determined in both urine and spleen samples, nor serum corticosterone levels showed significant variation between normal and CMS-animals. These findings demonstrate that chronic stress is associated with an increased sympathetic influence on the immune response and may suggest a mechanism through which chronic stress alters immunity.

Effects of chronic mild stress on lymphocyte proliferative response. Participation of serum thyroid hormones and corticosterone.

There is increasing evidence that stress produces changes in various immune processes. Some of these changes may be due to neurochemical and hormonal alterations including thyroid hormones levels. This work was carried out to study the impact of chronic mild stress (CMS) exposure on proliferative responses and its correlation with serum thyroid hormone levels. In addition, the influence of serum corticosterone levels on these responses was also studied. For this purpose, mice were submitted from1 to 6 weeks to a CMS model. After undergoing the stress schedule for 4 weeks, an alteration in the proliferative response was observed. Lymphocytes from exposed animals showed a decrease in T-cell response to concanavalin-A (Con A) and phytohemagglutinin (PHA) and an increase in B-cell proliferation to lipopolysaccharides (LPS). In parallel, a reduction in T3 and T4 serum levels was observed. On the contrary, serum corticosterone levels increased in animals exposed to CMS for 1 or 2 weeks and then return to normal values. Lowering serum thyroid hormone levels by propylthiouracil (PTU) treatment negatively modulates T-cell response without affecting B-cell response. On the other hand, the substitutive T4 treatment in stressed animals improved significantly the proliferative T-cell response. Non-significative changes in CD4/CD8 ratio were observed neither in stressed, PTU- or T4-treated animals. Taken together, our results suggest an impact of chronic stress on thyroid function that in turn alters T-cell response. These findings may help to elucidate the physiological mechanisms through which stress plays a roll in the etiology of many diseases.

Prenatal stress induces up-regulation of glucocorticoid receptors on lymphoid cells modifying the T-cell response after acute stress exposure in the adult life.

It has been demonstrated that a short-duration stress (acute stress) may result in immunopreparatory or immunoenhancing physiological conditions. The aim of the present study was to investigate whether exposure to prenatal restraint stress (PRS) influences the impact of acute stress on the T-cell response in the adult life. We found that female mice exposed to PRS (PS mice) did not exhibit changes in the T-cell-dependent IgG antibody production with respect to prenatally non-stressed mice (no-PS mice). However, no-PS mice exposed to acute stress showed an increase of antibody production after antigen stimulation. In contrast, PS mice exhibited a decreased response after an acute situation. Spleen catecholamines and plasma corticosterone levels were increased in acute stress in both PS and no-PS mice. Nevertheless, lymphocyte response to hormones was altered in PS mice. Particularly, inhibitory effect of corticosterone was higher on lymphocytes from PS mice. In addition, an increase in protein levels and mRNA expression of glucocorticoid receptor was found in lymphoid cells from PS mice. These results show that prenatal stress alters the immune intrinsic regulatory mechanism that in turn induces an increased vulnerability to any stressful situation able to modify immune homeostasis.