Psoriasis is a common chronic autoinflammatory/autoimmune
skin disease associated with elevated pro-inflammatory
cytokines. The pivotal role of
interleukin (IL)-1β and
nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing
protein 3 (NLRP3)
inflammasome in the pathogenesis of
psoriasis has been widely described. Accordingly, the suppression of NLRP3-dependent IL-1β release is a potential
therapy for
psoriasis. Repurposing marketed drugs is a strategy for identifying new inhibitors of NLRP3
inflammasome activation. Herein,
chlorquinaldol (CQD), a historic
antimicrobial agent used as a topical treatment for skin and vaginal
infections, was found to have a distinct effect by inhibiting NLRP3
inflammasome activation at concentrations ranging from 2 to 6 μM. CQD significantly suppressed apoptosis-associated speck-like
protein containing a caspase-recruitment domain (ASC) oligomerization, NLRP3-ASC interaction, and pyroptosis in macrophages. The levels of cleaved IL-1β and caspase-1 were reduced by CQD in the cell lysates of macrophages, suggesting that CQD acted on upstream of pore formation in the cell membrane. Mechanistically, CQD reduced mitochondrial
reactive oxygen species production but did not affect the nuclear factor-κB (NF-κB) pathway. Intraperitoneal administration of CQD (15 mg/kg) for 6 days was found to improve the skin lesions in the
imiquimod-induced psoriatic mouse model (male C57BL/6 mice), while secretion of pro-inflammatory
cytokines (IL-17 and IL-1β) and keratinocyte proliferation were significantly suppressed by CQD. In conclusion, CQD exerted inhibitory effects on NLRP3
inflammasome activation in macrophages and decreased the severity of psoriatic response in vivo. Such findings indicate that the repurposing of the old
drug, CQD, is a potential pharmacological approach for the treatment of
psoriasis and other NLRP3-driven diseases.