Mechanisms of Macrophage Activation and Function in Scleroderma

Dartmouth College, Hanover NH

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Abstract

DESCRIPTION (provided by applicant): Scleroderma is an autoimmune disease associated with vascular injury, fibrosis, and inflammation. Women develop scleroderma 7-12 times more often than men, suggesting estradiol may be involved in disease development and/or progression. There is no known cure for scleroderma and current treatments are limited. Progress in the development of therapies to combat scleroderma has been hampered by a lack of knowledge of the pathophysiology that underlies this disease. We recently reported that miR-125b, a microRNA aberrantly expressed in scleroderma patients, regulates activation of NF-KB. NF-KB is a master regulator of pro-inflammatory cytokines associated with disease activity in scleroderma. We hypothesize that aberrant regulation of miR-125b in scleroderma leads to enhanced activation of NF-KB and pro-inflammatory. We propose to test the following hypotheses: NF-KB cytokine production. The goal of this proposal is to determine how activation is dysregulated in scleroderma macrophages and to evaluate how modulation of miR-125b alters inflammation associated with this disease 1. That NF-KB activation differs between MØs derived from scleroderma patients vs. healthy controls. Activation of NF-KB contributes to pro-inflammatory cytokine production characteristic of scleroderma. Experiments in this aim will elucidate effects on transcriptional activation, DNA binding activity and localization of components of the NF-KB signaling complex. 2. That aberrant expression of miR-125b results in inappropriate activation of NF-KB in scleroderma MØs. Our studies have shown that miR-125b inhibits expression of ?B-Ras2, a negative regulator of NF-KB signaling. Aberrant expression of miR-125b has been reported in scleroderma patients. We will assess how aberrant expression of miR-125b inMØs derived from scleroderma patients affects NF-KB activation and pro-inflammatory cytokine production. 3. That estradiol differentially modulates miR-125b expression and NFkB activation in scleroderma MØs vs. healthy controls. This aim will elucidate how estradiol regulation of miR-125b in scleroderma MØs affects NFkB activation and inflammation.