Endoplasmic reticulum aminopeptidase 2 regulates CD4+ T cells pyroptosis in rheumatoid arthritis

Abstract

Objective Rheumatoid arthritis (RA) is a chronic, progressive autoimmune disease with a complex pathogenesis that has not yet been fully elucidated, and T-cell pyroptosis is an important pathogenetic factor in RA. This study aimed to investigate the role of endoplasmic reticulum aminopeptidase 2 (ERAP2) in the pyroptosis of CD4+ T cells in RA and the specific molecular mechanism. Methods Peripheral venous blood was collected from human subjects, and CD4+ T cells were isolated and activated to measure the level of pyroptosis and ERAP2 expression. Pyroptosis levels were assessed using immunofluorescence, flow cytometry, qRT-PCR, and Western blotting. Changes in pyroptosis levels were observed upon knockdown or overexpression of ERAP2. To detect activated Caspase-1 in tissues, chimeric mice were engrafted with human synovial tissue and reconstituted with human CD4+ T cells. CD4 + T cells were treated with GLI1 antagonists and SMO receptor agonists to detect changes in pyroptosis levels. Results CD4+ T cell levels undergoing pyroptosis were found to be elevated in the blood and synovium of RA patients. The gene and protein expression of ERAP2 were significantly higher in CD4+ T cells from RA patients. Deletion of ERAP2 suppressed pyroptosis of these cells, attenuated the activation of Caspase-1 in tissue T cells, and reduced tissue inflammatory responses. Reciprocally, overexpression of ERAP2 triggered inflammasome assembly, activated Caspase-1, and induced pyroptosis in CD4+ T cells. Mechanistically, ERAP2 inhibits the Hedgehog signaling pathway and upregulates the expression of nucleotide-binding oligomerization segment-like receptor family 3(NLRP3), cleaved Caspase-1, and Gasdermin D to promote pyroptosis in CD4+ T cells. Conclusions Taken together, our results identify a novel mechanism by which ERAP2 regulates RA development and document the effect of the ERAP2/Hedgehog signaling axis on pyroptosis of CD4+ T cells from RA patients.

ERAP Inhibitors in Autoimmunity and Immuno-Oncology: Medicinal Chemistry Insights

“…41 More recently, ERAP2 has been shown to inhibit the Hh signaling pathway that promotes pyroptosis in rheumatoid arthritis. 42 ERAP1 has also been implicated in cytokine receptors shedding or in inflammatory 4). (B) Alternatively ERAP enzymes can trim antigens into peptides that cannot bind the MHC-I anymore (5), resulting in no antigen to load on MHC-I (6) and no presentation (7).…”

“…For example, ERAP1 is a previously unknown player in the Hedgehog (Hh) signaling pathway and that its genetic inhibition suppresses Hh-dependent tumor growth both in vitro and in vivo , suggesting that ERAP1 is as a promising therapeutic target for Hh-driven tumors . More recently, ERAP2 has been shown to inhibit the Hh signaling pathway that promotes pyroptosis in rheumatoid arthritis . ERAP1 has also been implicated in cytokine receptors shedding or in inflammatory response as it induces macrophage phagocytosis and is involved in NO synthesis. , …”

“… 41 More recently, ERAP2 has been shown to inhibit the Hh signaling pathway that promotes pyroptosis in rheumatoid arthritis. 42 ERAP1 has also been implicated in cytokine receptors shedding or in inflammatory response as it induces macrophage phagocytosis and is involved in NO synthesis. 43 , 40 …”