SNX10‐mediated LPS sensing causes intestinal barrier dysfunction via a caspase‐5‐dependent signaling cascade

Abstract

Altered intestinal microbial composition promotes intestinal barrier dysfunction and triggers the initiation and recurrence of inflammatory bowel disease (IBD). Current treatments for IBD are focused on control of inflammation rather than on maintaining intestinal epithelial barrier function. Here, we show that the internalization of Gram-negative bacterial outer membrane vesicles (OMVs) in human intestinal epithelial cells promotes recruitment of caspase-5 and PIKfyve to early endosomal membranes via sorting nexin 10 (SNX10), resulting in LPS release from OMVs into the cytosol. Caspase-5 activated by cytosolic LPS leads to Lyn phosphorylation, which in turn promotes nuclear translocalization of Snail/ Slug, downregulation of E-cadherin expression, and intestinal barrier dysfunction. SNX10 deletion or treatment with DC-SX029, a novel SNX10 inhibitor, rescues OMV-induced intestinal barrier dysfunction and ameliorates colitis in mice by blocking cytosolic LPS release, caspase-5 activation, and downstream signaling. Our results show that targeting SNX10 may be a new therapeutic approach for restoring intestinal epithelial barrier function and promising strategy for IBD treatment.

Gut bacterial extracellular vesicles: important players in regulating intestinal microenvironment

“…In addition, knocking out SNX10 using CRISPR/Cas9 or treating with the SnX10 inhibitor DC-SX029 blocks LPS release, caspase-5 activation, and downstream signaling, effectively alleviating intestinal barrier dysfunction induced by E. coli BL21 EVs. 119 Although the E. coli BL21 used in this study is not a typical strain in the host gut, these findings are significant for research on IBD pathogenesis. Apart from LPS, GBEVs secreted by some enteropathogenic bacteria contain protein hydrolases.…”

“…Wang et al incubated E. coli BL21 EVs with Caco-2, HT-29, and NCM460 cells, and found that GBEVs reduced E-cadherin expression in cells in a concentration-dependent manner. 119 The team further found that internalization of E. coli BL21 EVs by IECs promotes the recruitment of caspase-5 and PIKfyve (involved in endosome maturation) to early endosomal membranes by sorting nexin 10 (SNX10, a member of the SNX family proteins), while promoting the release of LPS from GBEVs into the cytosol. Activated caspase-5 also leads to the phosphorylation of Lyn, the upstream regulator of Snail/Slug, which promotes nuclear translocalization of Snail/Slug and downregulates E-cadherin expression, ultimately leading to intestinal barrier dysfunction.…”

Caspase-4 and -5 Biology in the Pathogenesis of Inflammatory Bowel Disease

“…However, in the context of IBD the differential contributions of caspase-4 and -5 to inflammatory and other pathological events are not clear. Recently, Wang et al proposed that caspase-5 may contribute to intestinal barrier dysfunction, rather than pyroptosis, during IBD ( Wang et al, 2021 ). Sorting nexin 10 (SNX10) was shown to facilitate cytosolic release of LPS from OMVs by recruiting caspase-5 to the endosomal membrane.…”

“…Sorting nexin 10 (SNX10) was shown to facilitate cytosolic release of LPS from OMVs by recruiting caspase-5 to the endosomal membrane. Caspase-5 is reported to facilitate the down regulation of E-cadherin expression in a process dependent on Lyn phosphorylation and activation of Snail/Slug transcription factors ( Wang et al, 2021 ). Furthermore, knockdown or inhibition of SNX10 rescued OMV-induced barrier dysfunction and DSS-induced colitis symptoms in mice ( Wang et al, 2021 ).…”

“…Caspase-5 is reported to facilitate the down regulation of E-cadherin expression in a process dependent on Lyn phosphorylation and activation of Snail/Slug transcription factors ( Wang et al, 2021 ). Furthermore, knockdown or inhibition of SNX10 rescued OMV-induced barrier dysfunction and DSS-induced colitis symptoms in mice ( Wang et al, 2021 ). This finding provides further evidence for the complex and varied roles of non-canonical caspases at mucosal sites and the necessity for further research into basic caspase biology and their involvement in IBD pathogenesis.…”