TNF-alpha and psychologically stressful events in healthy subjects: potential relevance for multiple sclerosis relapse

Elevated Circulating Th2 Cells in Women With Asthma and Psychological Morbidity: A New Asthma Endotype?

PURPOSE

Psychological stress shifts the immune system toward the production of T-helper (Th)-2-mediated cytokines and eosinophilia, increases the risks for both asthma and depression, and can precipitate asthma exacerbations. Th2-mediated inflammation is a characteristic of allergic asthma. We have shown that the levels of CD4⁺ Th2 cells in the peripheral blood of patients with asthma are associated with severity and/or control of the disease. To improve our understanding of the interactions between stress and asthma symptoms, we evaluated the effects of psychological comorbidity on Th2-mediated inflammation in patients with asthma.

METHODS

Sixty-six asthmatic patients were recruited from the University of Alberta Asthma Clinic after they gave informed consent. Stress-related effects on asthma and psychological morbidity were assessed using the Asthma Control Questionnaire, completed by the patients at recruitment. Venous blood was collected at recruitment and Th2-mediated immunity evaluated by flow cytometry, quantitative real-time reverse-transcription polymerase chain reaction and enzyme-linked immunosorbent assay.

FINDINGS

Patients with stress-triggered asthma (n = 12) had higher percentage of CD4⁺ T cells (P = 0.006) and Th2 cells (CD4⁺CRTh2⁺ T cells; P = 0.002) in peripheral blood compared to patients with asthma who did not experience stress-related worsening of disease (n = 54). The same was true when we analyzed patients with any form of psychological comorbidity (n = 19) compared to those without psychological comorbidities (n = 47). These differences were evident among women, but not among men. Women with psychological comorbidity also required higher doses of inhaled and oral corticosteroids compared to those without psychological comorbidity.

IMPLICATIONS

Asthma involving psychological morbidity associates with an elevated level of circulating Th2 cells and increased corticosteroid usage, and may be more prevalent in women. Larger-scale prospective studies are required for assessing whether these women constitute a new endotype of Th2-high asthma responsive to treatments aimed to improve psychological comorbidities.

A review of stress-relapse interactions in multiple sclerosis: important features and stress-mediating and -moderating variables

Studies do not provide a consensus opinion of the relationship between stress and relapse in relapsing=remitting multiple sclerosis (RRMS). Few studies have defined the critical features of these stressful situations, or examined the role of stress-mediating and -moderating variables. Available evidence indicates that the relationship between life stress and relapse is complex, and is likely to depend on factors such as stressor chronicity, frequency, severity and type, and individual patient characteristics such as depression, health locus of control and coping strategy use. Little is known about how these factors, individually or in combination, are related to MS disease activity. Viral infections are also likely to precipitate relapse in MS, and significant life-stress may further enhance this relationship. The nature and strength of these interrelationships have strong clinical implications. MS patients are particularly vulnerable to a deteriorating cycle of stressful life events, illness episodes and disability. Timely multidisciplinary care interventions aimed at both minimizing psychological distress and physical symptoms may halt this downward reciprocal cycle. Little is known of the pathogenesis of these putative stress-induced changes in disease activity, and almost all stressor studies suffer from some biases or limitations.

Antidepressant-like effect of α-tocopherol in a mouse model of depressive-like behavior induced by TNF-α

Taking into account that pro-inflammatory cytokines and oxidative and nitrosative stress are implicated in the pathogenesis of depression and that α-tocopherol has antidepressant, anti-inflammatory and antioxidant properties, this study investigated the ability of α-tocopherol to abolish the depressive-like behavior induced by i.c.v. administration of TNF-α in the mouse TST. Additionally, we investigated the occurrence of changes in the levels of Bcl2 and Bax and phosphorylation of GSK-3β (Ser9) in the hippocampus of mice. The administration of TNF-α (0.001fg/site, i.c.v.) increased the immobility time in the TST, which was prevented by the administration of α-tocopherol at the doses of 10, 30 and 100mg/kg (p.o.). Subeffective doses of α-tocopherol (10mg/kg, p.o.) and/or the antidepressants fluoxetine (5mg/kg, p.o.), imipramine (0.1mg/kg, p.o.) and bupropion (1mg/kg, p.o.), the NMDA receptor antagonist MK-801 (0.001mg/kg, p.o.) or the neuronal nitric oxide synthase inhibitor 7-nitroindazole (25mg/kg, i.p.) prevented the depressive-like effect induced by TNF-α. None of the treatments altered the locomotor activity of mice. Treatment with TNF-α and/or α-tocopherol did not alter the levels of Bax and Bcl2 or the phosphorylation of GSK-3β in the hippocampus of mice. Together, our results show a synergistic antidepressant-like effect of α-tocopherol with antidepressants against the depressive-like behavior induced by an inflammatory insult, suggesting that this vitamin may be useful to optimize conventional pharmacotherapy of depression, including depressive states associated with inflammatory conditions.

Mast cells and inflammation

Mast cells are well known for their role in allergic and anaphylactic reactions, as well as their involvement in acquired and innate immunity. Increasing evidence now implicates mast cells in inflammatory diseases where they are activated by non-allergic triggers, such as neuropeptides and cytokines, often exerting synergistic effects as in the case of IL-33 and neurotensin. Mast cells can also release pro-inflammatory mediators selectively without degranulation. In particular, IL-1 induces selective release of IL-6, while corticotropin-releasing hormone secreted under stress induces the release of vascular endothelial growth factor. Many inflammatory diseases involve mast cells in cross-talk with T cells, such as atopic dermatitis, psoriasis and multiple sclerosis, which all worsen by stress. How mast cell differential responses are regulated is still unresolved. Preliminary evidence suggests that mitochondrial function and dynamics control mast cell degranulation, but not selective release. Recent findings also indicate that mast cells have immunomodulatory properties. Understanding selective release of mediators could explain how mast cells participate in numerous diverse biologic processes, and how they exert both immunostimulatory and immunosuppressive actions. Unraveling selective mast cell secretion could also help develop unique mast cell inhibitors with novel therapeutic applications. This article is part of a Special Issue entitled: Mast cells in inflammation.

Stress and body mass index each contributes independently to tumor necrosis factor-alpha production in prepubescent Latino children

This investigation extended prior work by determining if stress and body mass index (BMI) contributed independently to tumor necrosis factor-alpha (TNF-alpha) levels among prepubescent Latino children and if sex and family history of type 2 diabetes mellitus (T2DM) modified these relationships. Data were collected in South Florida from 112 nondiabetic school-aged Hispanic children, of whom 43.8% were obese (BMI >/= 95th percentile) and 51.8% presented with a family history of T2DM. Stressful life events were assessed via parental report using a life events scale. Plasma TNF-alpha levels were determined with enzyme-linked immunosorbent assay. The relative contributions of stress and BMI with TNF-alpha levels and the potential interaction effects of sex and family history of T2DM were analyzed with multiple linear regression analyses. Stress and BMI each accounted for a significant proportion of the unique variance associated with TNF-alpha. The association between stress and TNF-alpha was not modified by sex or family history of T2DM. These findings implicate BMI and stress as independent determinants of TNF-alpha (an inflammatory cytokine and adipocytokine) among Latino children. Future investigations should examine the potential roles of exercise, nutritional status, age, and growth hormone in explicating the relationship between TNF-alpha production and psychosocial distress and risk for infection among obese children.

Stress and hypothalamic-pituitary-adrenal axis function in experimental autoimmune encephalomyelitis and multiple sclerosis - a review

Multiple sclerosis (MS) is an inflammatory and degenerative disease of the CNS with an assumed autoimmune-mediated pathogenesis. Stressful life events have been hypothesized as potential triggers of disease exacerbation. Animal studies using experimental autoimmune encephalomyelitis (EAE), as a model for MS, suggest that decreased hypothalamic-pituitary-adrenal (HPA) function may play a role in the increased susceptibility and severity of the disease. Histopathological studies of the hypothalamus point to disturbances in corticotropin-releasing hormone (CRH) regulation as a result of MS lesions in this area. Functional endocrine tests (e.g., the combined Dexamethasone-CRH test) showed a disturbed negative feedback after steroid application in MS patients. Hyper- and hypoactivity of the HPA axis, have been described to be associated with more severe courses. This paper presents an overview of the evidence for a role of HPA dysfunction in EAE and MS based on stress-experimental studies.

Differential release of mast cell mediators and the pathogenesis of inflammation

Mast cells are well known for their involvement in allergic and anaphylactic reactions, during which immunoglobulin E (IgE) receptor (Fc epsilon RI) aggregation leads to exocytosis of the content of secretory granules (1000 nm), commonly known as degranulation, and secretion of multiple mediators. Recent findings implicate mast cells also in inflammatory diseases, such as multiple sclerosis, where mast cells appear to be intact by light microscopy. Mast cells can be activated by bacterial or viral antigens, cytokines, growth factors, and hormones, leading to differential release of distinct mediators without degranulation. This process appears to involve de novo synthesis of mediators, such as interleukin-6 and vascular endothelial growth factor, with release through secretory vesicles (50 nm), similar to those in synaptic transmission. Moreover, the signal transduction steps necessary for this process appear to be largely distinct from those known in Fc epsilon RI-dependent degranulation. How these differential mast cell responses are controlled is still unresolved. No clinically available pharmacological agents can inhibit either degranulation or mast cell mediator release. Understanding this process could help develop mast cell inhibitors of selective mediator release with novel therapeutic applications.