Lipopolysaccharide released from gut activates pyroptosis of macrophages via Caspase 11-Gasdermin D pathway in systemic lupus erythematosus.

Noncanonical pyroptosis is triggered by Caspase 4/5/11, which cleaves Gasdermin D (GSDMD), leading to cell lysis. While GSDMD has been studied previously in systemic lupus erythematosus (SLE), the role of pyroptosis in SLE pathogenesis remains unclear and contentious, with limited understanding of Caspase 11-mediated pyroptosis in this condition. In this study, we explored the level of Caspase 11-mediated pyroptosis in SLE, identifying both the upstream pathways and the interaction between pyroptosis and adaptive immune responses. We observed increased Caspase 5/11 and GSDMD-dependent pyroptosis in the macrophages/monocytes of both lupus patients and mice. We identified serum lipopolysaccharide (LPS), released from the gut due to a compromised gut barrier, as the signal that triggers Caspase 11 activation in MRL/lpr mice. We further discovered that pyroptotic macrophages promote the differentiation of mature B cells independently of T cells. Additionally, inhibiting Caspase 11 and preventing LPS leakage proved effective in improving lupus symptoms in MRL/lpr mice. These findings suggest that elevated serum LPS, resulting from a damaged gut barrier, induces Caspase 11/GSDMD-mediated pyroptosis, which in turn promotes B cell differentiation and enhances autoimmune responses in SLE. Thus, targeting Caspase 11 could be a viable therapeutic strategy for SLE.