Effect of IFN-β on MBP-cleaving proteolytic activities.

<p>Primary astrocytes (1×10⁵ cells/ml), incubated in serum-free DMEM, were treated with IFN-β at the indicated concentrations (U/ml) in the presence of LPS (10 µg/ml). After 24 h of incubation culture supernatants were collected and cells were lysed. 30 µl of lysates (A) or 50 µl of supernatants (B) were incubated for 24 h at 37°C with 10 µg of exogenous MBP in the presence of CaCl₂ (10 mM) and then subjected to SDS-PAGE. As controls, MBP was incubated without supernatants or lysates (MBP control) or with supernatants or lysates from non-activated astrocytes (CTRL). The positive control was represented by supernatants or lysates from LPS-activated astrocytes (LPS). Histograms show the percentage of non-degraded MBP compared to MBP control. Results represent the mean values ± SD of three separate experiments using lysates or supernatants from different cell populations. Statistically significant inhibition of MBP degradation in comparison to that of positive control is indicated with * (One way ANOVA followed by Student – Newman – Keuls post hoc test; * = p<0.05; **P<0.005).