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The intestinal epithelium is a complex, dynamic barrier that separates luminal contents from the immune compartment while mediating nutrient absorption and controlled passage of antigens to convey oral tolerance. A compromised epithelial barrier often leads to inflammation because immune cells in the lamina propria come into direct contact with luminal antigens. Defects in epithelial cell function were also shown to be involved in the etiology of inflammatory bowel diseases. These are severe, chronically relapsing inflammatory conditions of the gastrointestinal tract that also increase the risk of developing colorectal cancer. Despite major efforts of the scientific community, the precise causes and drivers of these conditions still remain largely obscured impeding the development of a permanent cure. Current therapeutic approaches mostly focus on alleviating symptoms by targeting immune cell signaling. The protein family of histone deacetylases (HDACs) has gained increasing attention over the last years, as HDAC inhibitors were shown to be potent tumor cell suppressors and also alleviate morbid inflammatory responses. Recent research continuously identifies new roles for specific HDACs suggesting that HDACs influence the cell signaling network from many different angles. This makes HDACs very interesting targets for therapeutic approaches but predicting effects after system manipulations can be difficult. In this review, we want to provide a comprehensive overview of current knowledge about the individual roles of HDACs in the intestinal epithelium to evaluate their therapeutic potential for inflammatory conditions of the gut.

Intact epithelial barrier function is pivotal for maintaining intestinal homeostasis. Current therapeutic developments aim at restoring the epithelial barrier in inflammatory bowel disease. Histone deacetylase (HDAC) inhibitors are known to modulate immune responses and to ameliorate experimental colitis. However, their direct impact on epithelial barrier function and intestinal wound healing is unknown. In human and murine colonic epithelial cell lines, the presence of the HDAC inhibitors Givinostat and Vorinostat not only improved transepithelial electrical resistance under inflammatory conditions but also attenuated the passage of macromolecules across the epithelial monolayer. Givinostat treatment mediated an accelerated wound closure in scratch assays. In vivo, Givinostat treatment resulted in improved barrier recovery and epithelial wound healing in dextran sodium sulphate-stressed mice. Mechanistically, these regenerative effects could be linked to an increased secretion of transforming growth factor beta1 and interleukin 8, paralleled by differential expression of the tight junction proteins claudin-1, claudin-2 and occludin. Our data reveal a novel tissue regenerative property of the pan-HDAC inhibitors Givinostat and Vorinostat in intestinal inflammation, which may have beneficial implications by repurposing HDAC inhibitors for therapeutic strategies for inflammatory bowel disease.

Inflammatory bowel disease (IBD) is characterized by dysregulated intestinal immune responses. Using mass cytometry (CyTOF) to analyze the immune cell composition in the lamina propria (LP) of patients with ulcerative colitis (UC) and Crohn's disease (CD), we observed an enrichment of CD4 + effector T cells producing IL‐17A and TNF, CD8 + T cells producing IFNγ, T regulatory (Treg) cells, and innate lymphoid cells (ILC). The function of these immune cells is regulated by store‐operated Ca 2+ entry (SOCE), which results from the opening of Ca 2+ release‐activated Ca 2+ (CRAC) channels formed by ORAI and STIM proteins. We observed that the pharmacologic inhibition of SOCE attenuated the production of proinflammatory cytokines including IL‐2, IL‐4, IL‐6, IL‐17A, TNF, and IFNγ by human colonic T cells and ILCs, reduced the production of IL‐6 by B cells and the production of IFNγ by myeloid cells, but had no effect on the viability, differentiation, and function of intestinal epithelial cells. T cell‐specific deletion of CRAC channel genes in mice showed that Orai1 , Stim1 , and Stim2 ‐deficient T cells have quantitatively distinct defects in SOCE, which correlate with gradually more pronounced impairment of cytokine production by Th1 and Th17 cells and the severity of IBD. Moreover, the pharmacologic inhibition of SOCE with a selective CRAC channel inhibitor attenuated IBD severity and colitogenic T cell function in mice. Our data indicate that SOCE inhibition may be a suitable new approach for the treatment of IBD. Synopsis The immune cell composition, signaling cascades, and cytokine networks controlling inflammation in therapy‐refractory inflammatory bowel diseases (IBD) remain incompletely understood. The colon lamina propria (LP) of ulcerative colitis (UC) and Crohn's disease (CD) patients is enriched with CD4 + and CD8 + T cells, IL‐17‐producing innate immune cells (ILC) and Treg cells. Pharmacological inhibition of store‐operated Ca 2+ Entry (SOCE) inhibits the production of proinflammatory cytokines and certain activation markers by human LP T cells, B cells, ILCs and myeloid cells. Inhibition of SOCE does not impair the differentiation and function of human or mouse intestinal epithelial cells in colonic organoid cultures. Pharmacologic inhibition of SOCE or T cell‐specific deletion of the SOCE genes Orai1 and Stim1 in T cells ameliorates intestinal inflammation in mouse models of colitis. SOCE is an important regulator of intestinal immune cell function and a potential drug target for the treatment of IBD. Graphical Abstract The immune cell composition, signaling cascades, and cytokine networks controlling inflammation in therapy‐refractory inflammatory bowel diseases (IBD) remain incompletely understood.

Primary human intestinal epithelial cells (IECs) require microenvironments that reproduce various in vivo cues to maintain survival, differentiation, and function in vitro . In this study, we investigated how intestinal stem cell (ISC)-derived monolayers respond to biomimetic substrates and shear stress using 3D-printed hydrogels based on bioactive decellularized and methacrylated small intestinal submucosa (dSIS-MA) integrated into a custom millifluidic system. Extensive bulk RNA sequencing experiments revealed that, compared with Matrigel-coated tissue culture plastic, dSIS-MA hydrogels supported survival- and differentiation-related signaling, stabilized gene expression over time, and promoted absorptive lineage maturation while reducing crypt-associated signatures. By applying dynamic culture conditions to the hydrogel system, IECs underwent transcriptional remodeling, characterized by activation of metabolic and immune pathways. Longitudinal analysis further indicated that shear stress enhanced metabolic pathway–associated gene expression and promoted differentiation toward absorptive lineages. These findings establish dSIS-MA hydrogels with controlled fluid flow as a biomimetic in vitro model that supports survival, maturation of human IECs and enables transcriptional adaptation to defined biochemical and mechanical cues, supporting future applications in disease modelling, drug testing, and regenerative medicine.

Multicellular cytokine networks drive intestinal inflammation and colitis-associated cancer (CAC). Interleukin-22 (IL-22) exerts both protective and pathogenic effects in the intestine, but the mechanisms that regulate this balance remain unclear. Here, we identify that IL-22 directly induces responsiveness to the IL-6 family cytokine oncostatin M (OSM) in intestinal epithelial cells (IECs) by activating STAT3 and upregulating the OSM receptor. In turn, OSM synergizes with IL-22 to sustain STAT3 activation in IECs and promote proinflammatory epithelial adaptation and immune cell chemotaxis to the inflamed intestine. Conditional deletion of the OSM receptor in IECs protects mice from both colitis and CAC, and pharmacological blockade of OSM attenuates established CAC. Thus, IL-22 and OSM form a pathogenic circuit that drives inflammation and tumorigenesis. Our findings reveal a previously unknown mechanism by which OSM supports intestinal pathology and highlight the IL-22–OSM axis as a promising therapeutic target for inflammatory bowel disease and CAC. Hegazy and colleagues demonstrate that epithelial oncostatin M receptor expression drives gut inflammation and tumor formation.