Skeletal muscle is a potential source of cytokines during heat stroke recovery in mice

Abstract

Skeletal muscle (SM) produces cytokines in response to exercise, but its role in cytokine production during heat stroke (HS) recovery is unknown. Mice show hypothermia and fever during HS recovery and these core temperature (Tc) responses are associated with high plasma cytokine and soluble cytokine receptor levels. We hypothesized that SM is a source of these proteins during mouse HS recovery. Gene expression of cytokines (IL‐1β, IL‐6, IL‐10, TNFα), cytokine receptors (gp130, IL‐6R) and TNFα converting enzyme (ADAM17) was measured in C57BL/6J mouse quadriceps at HS collapse (Tc,Max=42.7°C), hypothermia (HYPO; 29.3±0.4°C) and fever (24h; 37.8±0.3°C). HSP‐72 and ‐27 expression increased at Tc,Max, peaked at HYPO (217‐ and 40‐fold) and was elevated above controls at 24h (4‐ and 9‐fold). IL‐6 and IL‐10 expression increased ~4‐fold at HYPO with ~4‐fold decrease below controls by 24h. ADAM17 expression was ~6‐fold lower than controls at 24h. IL‐1β, TNFα, gp130 and IL‐6R did not change. These data suggest that HS induces cytokine gene expression in SM and this tissue may be a source of these proteins during HS recovery in mice. Research supported by MRMC. Author views not official US Army or DoD policy.