Online

Voorhees, Grace Kathryn

Pharmacology

2019

M.S.

Multiple Sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system, characterized by axonal demyelination and multifocal inflammation. Like many autoimmune diseases, it is a sexually dimorphic disease, being 3-4 times more common in females than in males. p38[alpha] MAP kinase (MAPK) has an integral role in modulating inflammatory processes in autoimmunity. Conditionally ablating p38[alpha] MAPK in myeloid cells in B6 mice shows a sex difference in the animal model of MS, experimental autoimmune encephalomyelitis (EAE). In the absence of sex hormones, this sex difference was reversed, suggesting a role for sex hormones in modulating p38[alpha] MAPK signaling in EAE. Based on these findings, we hypothesized that pro-inflammatory functions in EAE is p38-indepdendent in the presence of androgens and p38-dependent in the presence of estrogens. For the purposes of this project, the role of androgens was evaluated. Both in vivo and in vitro techniques were used to assess how androgen receptor (AR) signaling: 1) impacts EAE pathogenesis, and 2) impacts the role of p38[alpha] in EAE pathogenesis and macrophage function. To this end, using Cre-Lox technology, we generated mice deficient in: 1) AR globally or conditionally in macrophages, as well as 2) mice doubly deficient in AR and p38[alpha]. In vivo results from p38[alpha]-sufficient global AR knockout mice show no effect of global AR deletion on EAE pathogenesis. Surprisingly, results from p38[alpha]-sufficient conditional AR knockout mice showed significant worsening in disease compared to WT counterparts, suggesting that AR signaling in myeloid cells has a protective role in EAE pathogenesis. These findings implicate a protective role for AR signaling in EAE. Studies with mice doubly deficient in p38[alpha] and AR to determine whether AR regulates the role of p38[alpha] in EAE are ongoing, but so far show no effect on AR deletion on the role of p38[alpha] MAPK. Further studies with larger cohorts of mice are needed elucidate the relationship between AR and p38[alpha] MAPK signaling in myeloid cells in EAE pathogenesis. In vitro studies using the immortalized macrophage cell line RAW 264.7 showed that pharmacologic inhibition of p38 MAPK after stimulation with LPS reduced the production of classic pro-inflammatory cytokines IL-6 and TNF[alpha], and effect that was not affected by treatment with 5-dihydrotestosterone, suggesting that the AR does not modulate the role of p38[alpha] in cytokine production. These findings implicate no direct role of AR signaling on the functional role of p38[alpha] MAPK in the myeloid cell lineage in inflammatory and autoimmune responses.