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.
Keywords: Astrocytes, collagen, endothelial cells, fibrosis, multiple
sclerosis, pericytes