Sciatic denervation-induced skeletal muscle atrophy is associated with persistent inflammation and increased mortality during sepsis.

BACKGROUND: Patients with underlying skeletal muscle atrophy are likely to develop aggravated sepsis. However, no study has experimentally verified the association between the prognosis of sepsis and muscle atrophy, and the mechanism of aggravation of sepsis under muscle atrophy remains unclear. In this study, we investigated the effect of skeletal muscle atrophy induced by sciatic denervation (DN), an experimental muscle atrophy model, on sepsis prognosis.

METHODS: Skeletal muscle atrophy was induced by DN of the sciatic nerve in C57BL/6 J male mice. Cecal ligation and puncture (CLP) was performed to induce sepsis.

RESULTS: The survival rates of the sham and DN groups 7 days after CLP were 63% and 35%, respectively, wherein an approximately 30% reduction was observed in the DN group (P < 0.05, vs. sham-CLP). The DN group had a higher bacterial count in the blood 48 h after CLP (P < 0.05, vs. sham-CLP). Notably, NOx (a metabolite of nitric oxide) concentrations in DN mice were higher than those in sham mice after CLP (P < 0.05, vs. sham-CLP), whereas serum platelet levels were lower 48 h after CLP (P < 0.05, vs. sham-CLP). In organ damage analysis, DN mice presented increased protein expression of the kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL), a kidney injury marker, after CLP (NGAL 48 h after CLP, P < 0.05, vs. sham-CLP; KIM-1 24 h after CLP, P < 0.01, vs. sham-CLP). Furthermore, nitro tyrosine levels in the kidneys of DN mice were higher 48 h after CLP compared with those in sham-CLP mice, indicating the accumulation of nitrative stress (P < 0.05, vs. sham-CLP). Serum cytokine levels were increased in both groups after CLP, but decreased in the sham group 48 h after CLP and remained consistently higher in the DN group (tumor necrosis factor (TNF)-α: P < 0.05, sham-CLP vs. DN-CLP; interleukin (IL)-1β: P < 0.01, sham-CLP vs. DN-CLP; IL-6: P < 0.05, DN vs. DN-CLP; IL-10: P < 0.05, sham-CLP vs. DN-CLP).

CONCLUSIONS: We verified that skeletal muscle atrophy induced by DN is associated with poor prognosis after CLP-induced sepsis. Importantly, mice with skeletal muscle atrophy presented worsening sepsis prognosis at late onset, including prolonged infection, persistent inflammation, and kidney damage accumulation, resulting in delayed recovery.