Figure 4. Prolonged (15 days) exposure to IFNγ significantly reduces HO-1 protein expression, but not RNA expression in astrocytes.

Primary human fetal astrocytes were exposed to TNFα, LPS, and IFNγ (alone or in combination) for 15 days. Media and treatments were replaced every 3 days. (A) HO-1 and (B) HO-2 RNA expression was determined by real-time quantitative PCR. Fold change in expression was calculated relative to vehicle after normalization. (C) Representative Western blot from a single biological replicate. Quantification of (D) HO-1, (E) HO-2 and (F) NQO1 protein expression relative to vehicle after normalization. Data were log transformed and values represent mean ± SEM (n = 4 biological replicates) of the fold change in expression from vehicle (dotted line). Statistical comparisons to vehicle were made by RM-ANOVA with post hoc Holm-Sidak test. *P < 0.05; **P < 0.01; ***P < 0.001. Fold change in RNA and protein expression of (G) HO-1 and (H) HO-2 were individually plotted for each treatment condition from (n = 3 biological replicates, treatments and protein and RNA extraction occured in parallel wells). Solid black circles represent TNFα, LPS, and TNFα + LPS; solid red circles represent IFNγ, IFNγ + TNFα, and IFNγ + LPS.