Interleukin 6 (IL-6) is a cytokine that acts on a wide range of tissues influencing cell growth and differentiation. Here we show that IL-6 plays a role in the early vascular development (vasculogenesis) in the central nervous system (CNS). We report that IL-6 induces the proliferation of brain microvascular endothelial cells in vitro. Furthermore, IL-6 significantly accelerates the formation of tube-like structures by these cells in Matrigel basement matrix. Moreover, IL-6 mRNA is expressed in vivo in two physiological conditions in which vascularization in the CNS is important: (1) during normal brain development, (2) during the healing process of a traumatic brain injury. Expression of IL-6 mRNA coincides with the expression of vascular endothelial growth factor (VEGF) mRNA in the developing brain with decreasing expression following birth. However, IL-6 mRNA can be detected in the healing adult murine brain tissue by in situ hybridization coinciding with the period of intense tissue reorganization. The transient upregulation of IL-6 mRNA during normal brain development and at brain injury site and the effect of IL-6 on in vitro vasculogenesis suggest that IL-6 may play a role in normal physiology of vascularization in the CNS.
Copyright 2000 Academic Press.