Fig. 4.
Acute and chronic activation stimulate differential expression of TIMP-1, MMP-2, and MMP-1 in human astrocytes. In order to assess the effect of chronic immune activation on TIMP-MMP balance, astrocytes were cultured for different days, as indicated, in media with or without 20 ng/ml IL-1β and TIMP-1 profiles were compared. Control cells cultured in the absence of IL-1β were maintained in parallel. Culture medium was completely exchanged daily with media supplemented with or without IL-1β. All culture super-natant samples were collected and cellular MTT activity was measured. Supernatant samples were analyzed using TIMP-1 (A), MMP-2 (B), and MMP-1 (C) ELISA kits. Each time point was performed in independent triplicate determinations. Data were analyzed with GraphPad Prism 3.0 and one-way ANOVA. Error bars represent standard error of the mean. The effect of chronic activation was evaluated using three independent astrocyte donors.