Inflammation & glucocorticoid signaling in early life stress and major depression

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DESCRIPTION (provided by applicant): Major Depression (MD) has been associated with increased baseline inflammatory responses that are believed to contribute to the association of MD with certain medical co-morbidities. MD is also often accompanied by hypothalamic-pituitary adrenal axis abnormalities, including altered cortisol release and impaired glucocorticoid receptor (GR) function. Interestingly, recent data indicates that male MD patients with increased early life stress (ELS) exhibit increased stress-induced inflammatory responses that are associated with reduced plasma cortisol responses to stress and preliminary evidence of decreased glucocorticoid sensitivity. The long term objectives of the proposed research are to further examine the contribution of altered cortisol release and GR function (reduced glucocorticoid sensitivity) to excessive inflammation in patients with MD, and to evaluate the contribution of ELS. The primary hypothesis of the proposed work is that excessive inflammation under resting conditions and after stress in men with MD and ELS is the result of insufficient glucocorticoid inhibition of inflammatory responses; a process that is modulated by independent contributions from ELS (reduced cortisol secretion) and MD (reduced GR function). To test this hypothesis, the following specific aims are proposed: Aim 1) to measure baseline and stress-induced activation of inflammatory responses in male MD patients and healthy controls with or without ELS (n=17 per group), Aim 2) to correlate activation of inflammatory responses with baseline and stress-induced activation of cortisol as well as GR function, and Aim 3) to measure molecular interactions between inflammatory signaling pathways and GR signaling pathways in vivo and in vitro. Men will be recruited from an ongoing Emory Conte Center project examining the consequences of ELS on neurobiology and behavior. For studies examining stress-induced immune and neuroendocrine activation, the Trier Social Stress Test (TSST) will be employed. Inflammatory measures before, during, and after stress will include inflammatory signaling pathway activation (e.g. NF- and MAPK) and plasma inflammatory markers including acute phase reactants and proinflammatory cytokines. Neuroendocrine measures will include plasma cortisol and assessments of GR function (e.g. GR-DNA-binding and GR nuclear localization). In vitro studies (conducted on blood samples obtained prior to the TSST) will employ lipopolysaccharide and anisomycin to activate NF- dexamethasone to activate GR signaling pathways. Protein-protein interactions between relevant inflammatory and GR signaling pathways will be explored by immunoprecipitation and DNA-binding characteristics of relevant neuroendocrine and inflammatory transcription factors. Informed by the results from these experiments, future studies will focus on a similar sample of female subjects. This application will help to identify molecular targets at the endocrine-immune interface and may provide novel insights into the pathophysiology of MD and ELS and their relationship to medical illnesses. Excessive inflammation and abnormal endocrine function are emerging as important elements in major depression. The goal of this grant is to understand differences in the underlying pathophysiology of major depression in men with traumatic early life experiences (e.g. sexual abuse), compared to men without such a history. Such an understanding may help individualize treatment strategies for individuals with major depression based on both psychosocial and biological phenotypes.