NLRC3 affects the development of psoriasis by modulating the NF-κB signaling pathway mediated inflammatory response through its interaction with TRAF6.

Abstract

Objective: The function and mechanism of NOD-like receptor family CARD-containing 3 (NLRC3) in psoriasis are not yet reported, even though it plays a crucial role in innate and adaptive immunity by inhibiting inflammation. Therefore, this research aims to investigate the role and mechanism of NLRC3 in psoriasis.

Methods: HaCaT cells were induced to form a psoriasis cell model using 20 ng/mL IL-1β, 20 ng/mL IL-17A, 20 ng/mL IL-23, 50 ng/mL TNF-α, and 20 ng/mL oncostatin M. Cell Counting Kit-8 (CCK-8) assay and flow cytometry were assessed to determine the proliferation, cell cycle, and apoptosis of HaCaT cells. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was utilized to measure the knockdown efficiency of NLRC3 and TRAF6 interfering RNA in HaCaT cells. Western blot analysis was performed to determine the expression levels of NLRC3, TRAF6, and proteins associated with the NF-κB signaling pathway. A mouse model of psoriasis-like dermatitis was established by evenly applying miquimod cream (62.5 mg/day) to both ears. Hematoxylin-eosin staining was used to measure ear thickness and inflammatory infiltrates in mice. Histological analysis, immunohistochemistry, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL were performed to detect cell proliferation and apoptosis. Interactions between NLRC3 and TRAF6 were predicted using the STRING database (https://cn.string-db.org/). Co-Immunoprecipitation was used to confirm interactions between NLRC3 and TRAF6. Ubiquitination of TRAF6 was assessed by Western blot.

Results: Knockdown of NLRC3 expression promoted cell proliferation and inhibited cell apoptosis in HaCaT cells. In vivo, knockdown of NLRC3 expression significantly increased the infiltration of inflammatory cells and the proliferation of Ki-67 positive cells within mouse ear epidermis, while decreasing the number of apoptotic cells. NLRC3 interacted with TRAF6 and influenced its K63 ubiquitination level. Knockdown of TRAF6 expression resulted in increased cell proliferation and decreased cell apoptosis in HaCaT cells. In vivo, knockdown of TRAF6 expression led to a significant increase in inflammatory cell infiltration and Ki-67 positive cells in mouse ear epidermis, and a decrease in apoptotic cells. Inhibiting the NF-κB signaling pathway alleviated the progression of psoriasis, and interfering with TRAF6 activated the NF-κB signaling axis, contributing to the onset and advancement of psoriasis.

Conclusion: NLRC3 affects the occurrence of psoriasis by regulating TRAF6 and influencing the NF-κB signaling axis-mediated inflammatory response. This finding offers a theoretical foundation for the treatment of psoriasis.