Targeting intracellular oncoproteins with dimeric IgA promotes expulsion from the cytoplasm and immune-mediated control of epithelial cancers

Dimeric IgA (dIgA) can move through cells via the IgA/IgM polymeric immunoglobulin receptor (PIGR), which is expressed mainly on mucosal epithelia. Here, we studied the ability of dIgA to target commonly mutated cytoplasmic oncodrivers. Mutation-specific dIgA, but not IgG, neutralized KRASG12D within ovarian carcinoma cells and expelled this oncodriver from tumor cells. dIgA binding changed endosomal trafficking of KRASG12D from accumulation in recycling endosomes to aggregation in the early/late endosomes through which dIgA transcytoses. dIgA targeting of KRASG12D abrogated tumor cell proliferation in cell culture assays. In vivo, KRASG12D-specific dIgA1 limited the growth of KRASG12D-mutated ovarian and lung carcinomas in a manner dependent on CD8+ T cells. dIgA specific for IDH1R132H reduced colon cancer growth, demonstrating effective targeting of a cytoplasmic oncodriver not associated with surface receptors. dIgA targeting of KRASG12D restricted tumor growth more effectively than small-molecule KRASG12D inhibitors, supporting the potential of this approach for the treatment of human cancers.

Intestinal Epithelial Responses to IL-17 in Adult Stem Cell-derived Human Intestinal Organoids

BACKGROUND

Th17 cells and their signature cytokine, interleukin-17A [IL-17], are considered as the main pathogenic factors in inflammatory bowel diseases [IBDs]. However, IL-17 neutralising antibodies, a theoretically curative medication for IBDs, paradoxically aggravated intestinal inflammation. The mechanisms by which IL-17 mediates the protective and pathological effects of IL-17 remain unclear in the intestinal epithelium.

METHODS

The intestinal epithelial responses induced by IL-17 were evaluated using the human small intestinal organoid [enteroid] model.

RESULTS

Organoid-forming efficiency, cell viability, and proliferation of enteroids were decreased in proportion to IL-17 concentration. The IL-17 induced cytotoxicity was predominantly mediated by pyroptosis with activation of CASP1 and cleavage of GSDMD. Bulk RNA-sequencing revealed the enrichment of secretion signalling in IL-17 treated enteroids, leading to mucin exocytosis. Among its components, PIGR was up-regulated significantly as the concentration of IL-17 increased, resulting in IgA transcytosis. Mucin exocytosis and IgA transcytosis have a protective role against enteric pathogens. Single-cell RNA sequencing identified that CASP1-mediated pyroptosis occurred actively in intestinal stem cells [ISCs] and enterocytes. IL-17 neutralising antibody completely restored IL-17 induced cytotoxicity, but suppressed mucin secretion and IgA transcytosis. Pyroptosis inhibition using CASP1 inhibitors significantly improved IL-17 induced cytotoxicity without diminishing its beneficial effects.

CONCLUSIONS

IL-17 induces the pyroptosis of ISCs and enterocytes, as well as mucin secretion of goblet cells and IgA transcytosis of epithelial cells. Paradoxical gastrointestinal effects of IL-17 neutralising antibodies may be associated with inhibition of mucin secretion and IgA transcytosis. The inhibition of pyroptosis using CASP1 inhibitors prevents IL-17 induced cytotoxicity without compromising its beneficial effects.