Differentiated embryonic chondrocyte expressed gene-1 is a central signaling component in the development of collagen-induced rheumatoid arthritis

Stigmasterol mitigates rheumatoid arthritis progression by decreasing Nrf2/NLRP3-mediated pyroptosis in chondrocyte

Stigmasterol (Stig), a phytosterol with anti-inflammatory and antioxidant properties, has been shown to have potential therapeutic effects. In this study, we aimed to investigate whether Stig mitigates rheumatoid arthritis (RA) progression by reducing chondrocyte injury. A mouse model of RA was established by intradermally injecting type II collagen into the tail roots of mice. The arthritic score and spleen index were measured in RA mice to assess the effects of Stig on RA progression. Lipopolysaccharide (LPS)-treated chondrocytes were used as a cellular model of RA. The roles of Stig in chondrocyte viability, proliferation, migration, inflammation, and injury were assessed using Cell Counting Kit-8, EdU, Transwell assays, quantitative real-time PCR, and western blotting, respectively. The results demonstrated that Stig exhibited no significant cytotoxicity in CHON-001 chondrocytes. Interestingly, it effectively inhibited LPS-induced apoptosis and increased cell viability, proliferation, and migration. Stig also alleviated LPS-induced pro-inflammatory responses and CHON-001 cell injury. Mechanistically, Stig activated nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, which led to the inactivation of the NOD-like receptor protein 3 (NLRP3) inflammasome and a subsequent decrease in CHON-001 cell pyroptosis. However, the protective effects of Stig were abrogated by ML385, a specific inhibitor Nrf2. Stig treatment further improved the clinical severity in RA mice. In summary, Stig reduces LPS-induced chondrocyte injury and mitigates RA progression by inhibiting Nrf2/NLRP3-mediated pyroptosis, offering a potential therapeutic approach for RA.

Bhlhe40 deficiency attenuates LPS-induced acute lung injury through preventing macrophage pyroptosis

BACKGROUND

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) as common life-threatening lung diseases with high mortality rates are mostly associated with acute and severe inflammation in lungs. Recently, increasing evidence supports activated inflammation and gasdermin D (GSDMD)-mediated pyroptosis in macrophage are closely associated with ALI. Basic helix-loop-helix family member e40 (Bhlhe40) is a transcription factor that is comprehensively involved in inflammation. However, there is little experimental evidence connecting Bhlhe40 and GSDMD-driven pyroptosis. The study sought to verify the hypothesis that Bhlhe40 is required for GSDMD-mediated pyroptosis in lipopolysaccharide (LPS)-induced inflammatory injury.

METHOD

We performed studies using Bhlhe40-knockout (Bhlhe40 -/-) mice, small interfering RNA (siRNA) targeting Bhlhe40 and pyroptosis inhibitor disulfiram to investigate the potential roles of Bhlhe40 on LPS-induced ALI and the underlying mechanisms.

RESULTS

Bhlhe40 was highly expressed in total lung tissues and macrophages of LPS-induced mice. Bhlhe40-/- mice showed alleviative lung pathological injury and inflammatory response upon LPS stimulation. Meanwhile, we found that Bhlhe40 deficiency significantly suppressed GSDMD-mediated pyroptosis in macrophage in vivo and in vitro. By further mechanistic analysis, we demonstrated that Bhlhe40 deficiency inhibited GSDMD-mediated pyroptosis and subsequent ALI by repressing canonical (caspase-1-mediated) and non-canonical (caspase-11-mediated) signaling pathways in vivo and in vitro.

CONCLUSION

These results indicate Bhlhe40 is required for LPS-induced ALI. Bhlhe40 deficiency can inhibit GSDMD-mediated pyroptosis and therefore alleviate ALI. Targeting Bhlhe40 may be a potential therapeutic strategy for LPS-induced ALI.