Figure 3. Influenza infection induced muscle-localized inflammatory gene expression in the gastrocnemius that is prolonged and elevated in aged mice. Young and aged C57BL/6 mice were intranasally infected with 500 EID50 of PR8 influenza. At day 0, 3, 7, 11, and 15, mice fasted for 4-6 hours prior to sacrifice and gastrocnemius muscle was harvested and RNA was isolated. Gene expression was analyzed via RT-qPCR and normalized to reference genes and expression of young mice at day 0 to indicate fold changes. Influenza induced increased expression of IL6 (A) and IL6RA (B). Increased TNF (C) and CXCL10 (D) expression was observed in the aged mice. All data was log-transformed and analyzed via two-way ANOVA with Bonferroni post hoc corrections with effect of flu infection over time (compared to day 0, p<0.05) indicated by brackets above data and differences between young and aged mice (p<0.05) at time points indicated by asterisk.