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P010 GSDMB-mediated pyroptosis exacerbates intestinal inflammation by destroying intestinal epithelium in Crohn’s disease

Gong, W.(1);Liu, P.(2);Ren, J.(3);

(1)Southeast University, School of Medicine, Nanjing, China;(2)Nanjing University, School of Medicine, Nanjing, China;(3)Jinling Hospital, General Surgerry, Nanjing, China

Background

Intestinal epithelial injury acts an essential role in the pathogenesis and development of Crohn’s disease (CD). Recent studies indicated that gasdermin D (GSDMD) mediated pyroptosis in intestinal epithelial cell (IEC) contributes to the epithelial injury during intestinal inflammation. However, how gasdermin B (GSDMB) mediated pyroptosis regulates intestinal epithelial injury in CD remains unknown.

Methods

We studied the characteristics of GSDMB mediated pyroptosis in CD patients and intestinal epithelial cells (Caco-2, HT-29 and primary IECs). The CD8+ T cells were extracted from intestinal mucosa of CD patients and health controls, and then co cultured with normal primary IECs to observe the pyroptosis of IECs. We further analyzed the CD8+ T cell subsets that promote pyroptosis in intestinal biopsies of CD patients. In addition, we screened out four single nucleotide polymorphism (SNP) of GSDMB that related to disease risk of CD in the public IBD exomes database (https://ibd.broadinstitute.org/), and investigated their effects on pyroptosis.

Results

GSDMB mediated pyroptosis was notably increased in intestinal mucosa of active human CD, and only existed in intestinal epithelial cells (Figure 1). Granzyme A (GrzA) initiated the killing results by the cleavage of GSDMB in intestinal epithelial cells, and interferon gamma (IFN-γ) up-regulated GSDMB expression in intestinal epithelial cells and promoted pyroptosis (Figure 2). GSDMB in primary IECs was significantly cleaved when co cultured with CD8+ T cells from active CD patients, while the phenomenon weakened a lot when GrzA in CD8+ T cells or GSDMB in epithelial cells was knocked down (Figure 3). We also found that IL26 possive CD8+ T cells were the main CD8+ T cells subsets secreting GrzA (Figure 3). We screened out two SNP of GSDMB related to increased disease risk of CD (rs2305480 and rs11078928) and two related to decreased disease risk (rs35104165 and rs143933205), and constructed these four mutant plasmids. Compared with wild type of GSDMB, rs2305480 promoted the cleavage while rs35104165 blocked the cleavage (Figure 4).

Conclusion

GSDMB-mediated pyroptosis results in intestinal epithelial injury, which will exacerbate intestinal inflammation. Modulation of the GSDMB-mediated pyroptosis emerges as a potential therapeutic strategy to target epithelium damage and treat CD. 

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