Fig. 5

IL-24 augments the expression of suppressive cytokine signaling components by murine astrocytes and limits inflammatory cytokine release by these cells. a Astrocytes were untreated or treated with recombinant IL-24 (10, 30, or 100 ng/mL) for 30 min and the presence of phosphorylated STAT3 and STAT1 was determined by immunoblot analysis. Expression of β-actin is shown as a loading control and these immunoblots are representative of two separate experiments. b Astrocytes were untreated or treated with recombinant IL-24 (10, 30, or 100 ng/mL) for 2 or 4 h, and SOCS3 mRNA expression was determined by semi-quantitative RT-PCR. Expression of the housekeeping gene product GAPDH is shown, and relative SOCS3 expression was determined by densitometric analysis and normalized to untreated cells. Data is expressed as the mean ± the SEM of three independent experiments, and an asterisk indicates a statistically significant difference from unchallenged cells at each time point (p < 0.05). c Astrocytes were untreated or treated with recombinant IL-24 (10, 30, or 100 ng/mL) for 8 h prior to immunoblot analysis for SOCS3 protein expression. Expression of the housekeeping gene β-actin is shown and relative SOCS3 protein expression was determined by densitometric analysis normalized to untreated cells. Asterisks indicate statistically significant differences from unchallenged cells (p < 0.05). d Astrocytes were untreated or treated with IL-24 (0.5, 3, 10, 30, or 100 ng/mL) for 4 h prior to challenge with bacterial LPS (5 ng/mL) or vehicle control for 12 h, and IL-6 secretion was determined by specific capture ELISA. Asterisks indicate a statistically significant difference (p < 0.05) from similarly challenged cells in the absence of IL-24 (n = 3). e Primary astrocytes were untreated or treated with recombinant IL-24 (10, 30, or 100 ng/mL) for 4 h prior to being uninfected or infected with Nm for 48 h before cell viability analysis via MTS assay. Data is presented as the mean absorbance ± SEM for three experiments. 0.1% Triton X-100 was used as a positive control, and an asterisk indicates a statistically significant difference from unchallenged cells in the absence of IL-24 (p < 0.05)