T‐cell immunosuppression in sepsis is augmented by sciatic denervation‐induced skeletal muscle atrophy

Skeletal muscle atrophy is a known risk factor for immunosuppressive conditions and for a poor prognosis in sepsis. However, its immunopathology has not been experimentally elucidated. This study investigated the effects of skeletal muscle atrophy on the immunopathology of sepsis. Male C57BL/6J mice were subjected to sciatic denervation (DN) and caecal ligation and puncture (CLP) to induce muscle atrophy or sepsis. The macrophages, myeloid-derived suppressor cells (MDSC), and T-cells in peritoneal and spleen were analysed using flow cytometry. DN-induced muscle atrophy did not affect macrophage and MDSC populations. In contrast, the percentage of cytotoxic T-lymphocyte-associated antigen (CTLA)-4⁺ CD4⁺ T-cells, programmed death (PD)-1⁺ CD8⁺ T-cells, regulatory T-cells, and the CTLA-4⁺ regulatory T-cells was statistically significantly higher in DN-CLP mice than in sham-CLP mice. Skeletal muscle atrophy before sepsis triggers excessive T cell immunosuppression, which may contribute to the exacerbation of sepsis under skeletal muscle atrophy.