The host defense peptide LL-37 a possible inducer of the type I interferon system in patients with polymyositis and dermatomyositis

Neutrophil dysregulation is pathogenic in idiopathic inflammatory myopathies

“…Neutrophil infiltration was observed in IIM skin, while the presence of netting neutrophils was particularly evident in the anti-MDA5-positive group. The presence of infiltrating neutrophils in IIM skin supports the findings of a previous publication reporting that the cathelicidin LL-37, derived from these infiltrating neutrophils, can promote type I IFN responses in IIM (29). Furthermore, levels of circulating NETs significantly correlated with skin disease activity, further implicating these cells in the pathogenesis of DM.…”

Aberrant activation of the type I interferon system may contribute to the pathogenesis of anti‐melanoma differentiation‐associated gene 5 dermatomyositis

“…The levels of cathelicidin LL‐37, an important component of NETs, were demonstrated to be elevated notedly in peripheral blood from patients with anti‐MDA5 DM. LL‐37 has been suggested as a possible inducer of type I IFN system activation in human autoimmune diseases such as lupus and DM . The production of type I IFN could in turn induce the high expression of TLR3–TLR7 and MDA5–RIG‐I, which form the feed‐forward loop contributing to the aberrant overproduction of type I IFN.…”

Exacerbation of Murine Experimental Autoimmune Myositis by Toll‐Like Receptor 7/8

“…Viral infection has been convincingly associated with autoimmunity, activation of TLRs, and the generation of potent adjuvant signals such as type I IFNs (15,22,(24)(25)(26)(27)41). Immune complexes containing relevant myositis antigens, including HisRS, stimulate TLRs of IFN-producing cells (42), which are found in the muscle and skin of IIM patients (43) and amplify IFN production in an autocrine manner (44).…”