The Fibrotic Response in Pericyte Culture Upon Exposure to Multiple Sclerosis Sera.

Introduction: Multiple sclerosis (MS) is a chronic autoimmune and demyelinating disease of central nervous system (CNS) leading to progressive function loss. Besides infiltration of peripheral immune cells into CNS subsequent to neuroinflammation, the accumulation of extracellular matrix (ECM) elements, produced by brain barrier cells, in the enlarged perivascular spaces contributes to the pathophysiology. In this study, we aimed to develop an in-vitro model of MS to investigate fibrosis triggered by sera or cerebrospinal fluid (CSF) from MS patients and evaluate the response of blood-brain barrier (BBB) cells to this model.

Methods: Human brain vascular pericytes, endothelial cells and normal human astrocytes were cultured and exposed to a cytokine reference control (Transforming growth factor beta 1 (TGF-β1)), healthy human sera, and sera/CSF from treatment naïve relapsing-remitting MS patients with the appropriate dilution dose. The pericytes cell proliferation were evaluated by xCELLigence, while the collagen and fibronectin expressions of BBB cells, and pericyte myofibroblastic transformation were analyzed with immunocytochemistry.

Results: TGF-β1 induced fibrosis, characterized by fibronectin overexpression, specifically in pericyte cultures. Furthermore, incubation of pericytes with MS serum but not CSF led to a more robust fibrotic response (fibronectin/collagen overexpression), myofibroblastic transformation as well as increased proliferation. Fibronectin overexpression was also detected in endothelial cell culture with MS serum. Glial fibrillary acidic protein (GFAP) expression is increased, but fibrotic markers are decreased in cultured astrocytes with MS serum.

Conclusion: Pericytes, among BBB-forming cells, were identified as key contributors to fibrosis in response to MS serum. MS-serum-induced in vitro models are promising for studying the individualized tendencies of patients and may be a new approach for high-throughput screening of potential treatment agents.