Analysis of glial cell TIMP-1 expression in response to cytokines and LPS. TIMP-1 expression was examined by western blot of cell culture supernatants, as described in Materials and Methods. A. The influence of LPS on TIMP-1 expression in the three different types of glial culture. MGC, astrocytes, and microglial cultures were treated with LPS for 2 days, then cell culture supernatants examined for TIMP-1 expression. Note that cultures not treated with LPS did not express TIMP-1, and TIMP-1 protein (~28 kD band) was induced only in MGC following LPS stimulation. B. TIMP-1 induction in astrocytes in the presence of activated microglia or MG-CM. Pure astrocyte cultures received either: LPS, microglia + LPS, or LPS-activated MG-CM. Note that the presence of LPS-activated microglia or LPS-activated MG-CM strongly induced TIMP-1 expression in astrocytes. C. The influence of cytokines on TIMP-1 expression by astrocytes. Pure astrocyte cultures were treated with a panel of different cytokines for 2 days, and the supernatants analyzed for TIMP-1 expression. Note that of the cytokines tested, only IL-1β stimulated TIMP-1 expression in astrocytes.