Fig. 5.

The influence of LPS, IL-1β, or TNF-α on MMP-9 expression in mixed glial cultures (MGC), pure astrocytes (astro) or pure microglia. The three different types of culture were prepared, as described in the Materials and Methods section, and then cultured in serum-free medium on poly-d-lysine coated plates. After 2-days culture, cell supernatants were analyzed for MMP-9 activity by gel zymography. Note that LPS and TNF-α stimulated strong expression of MMP-9 in both the MGC and pure microglial cultures. In contrast, pure cultures of astrocytes did not express MMP-9 in response to LPS and expressed only minimal levels in response to TNF-α. IL-1β evoked no detectable MMP-9 in any of the cultures.