Thrombin and TGF-beta promote human leptomeningeal cell proliferation in vitro.

Some disorders of the central nervous system, such as trauma, meningitis, or subarachnoid hemorrhage (SAH), result in inflammation and fibrosis of the arachnoid membranes followed by hydrocephalus. To clarify the role of growth factors in the pathophysiology of arachnoid fibrosis, we investigated the response of leptomeningeal (LM) cells to growth factors elevated in the cerebrospinal fluid (CSF) of patients with subarachnoidal inflammation. We examined the proliferative responses of LM cells to thrombin, transforming growth factor-beta (TGF-beta), epidermal growth factor (EGF), acidic fibroblast growth factor (aFGF), platelet derived growth factor (PDGF), tumor necrosis factor-beta (TNF-beta) and interleukin 1-beta (IL1-beta). Thrombin, TGF-beta, EGF, aFGF and PDGF promoted LM cell proliferation. TGF-beta enhanced the proliferative effect of thrombin and EGF on LM cells. These findings suggest that thrombin and TGF-beta, which may be elevated in CSF following SAH, may cause subarachnoid fibrosis and subsequent hydrocephalus.