Activation of NLRP3 Inflammasome in the Skin of Patients with Systemic and Cutaneous Lupus Erythematosus

Abstract

NLRP3 inflammasome is suggested to contribute to the complex pathogenesis of systemic lupus erythema-tosus, but its role in cutaneous lupus erythematosus has not been addressed. This study investigated the expression of NLRP3 inflammasome components and levels of type I interferons in the skin of 20 patients with cutaneous lupus erythematosus. Expression of NLRP1/3, adaptor protein ASC (apoptosis-associated speck-like protein), caspase-1, interferon-α (IFN-α), myxovirus resistance protein (MxA), and interferon-induced proteins 1 and 2 (IFIT 1/2) in the skin was assessed using reverse transcription quantitative real-time PCR (RT-qPCR), western blotting and immu-nohistochemistry. Serum interferon-α protein levels from 12 patients were measured using digital enzyme-linked immunoassay (ELISA). Interleukin-1β expression was significantly upregulated in the lesional skin of patients with cutaneous lupus erythematosus compared with their uninvolved skin. However, NLRP1/3, ASC and caspase-1 were not significantly upregulated compared with the skin of control persons. IFN-α and IFN-induced proteins MxA and IFIT1/2 were strong-ly expressed in cutaneous lupus erythematosus skin. Variability in the expression of NLRP3 inflammasome components among patients suggests heterogeneity of pathological pathways in cutaneous lupus erythematosus.