MMP9 and polymyositis: IL-15 promotes the production of MMP9 in human peripheral blood mononuclear cells (PBMCs),[59] or induces macrophage infiltration in polymyositis through regulating the NF-kB signaling pathway.[60]MMP9 is a macrophage gene, and its expression is upregulated in patients with sepsis.[61] Our present study showed the expression of IL-15, NFKBIA, MMP8, and MMP9 were significantly upregulated in the neutrophil samples from patients with sepsis-induced immunosuppression.