Background: Crohn’s disease (CD) is an incurable chronic intestinal inflammatory disease with no recognized cause. It has been reported that the mechanosensitive ion channel PIEZO1 initiates proinflammatory responses. However, little is known about the role of PIEZO1 in CD. Methods: Ileum biopsies were obtained from 30 patients with CD and 15 healthy volunteers. Clinical data were collected to determine the relationship between CD and PIEZO1. First, HT29 cells were incubated with Yoda1 and GsMTx4 (Grammostola spatulata mechanotoxin 4) to activate and inhibit PIEZO1, respectively. Second, PIEZO1 knockdown was performed using small interfering RNA. Third, calcium imaging, flow cytometry, and immunofluorescence were used to detect intracellular calcium and mitochondrial function. Last, real-time quantitative polymerase chain reaction, immunoblotting, and enzyme-linked immunosorbent assay were used to quantify PIEZO1, proinflammatory cytokines, and NLRP3 (NOD-like receptor 3)–related compounds. Results: PIEZO1 was highly expressed in the ileum of patients with CD and correlated positively with the Crohn’s Disease Activity Index, platelet count, and hematocrit and fecal calprotectin levels. In HT29 cells, Yoda1 triggered calcium influx, which was inhibited by GsMTx4 treatment and small interfering RNA–mediated PIEZO1 knockdown. Increased calcium concentrations resulted in increased reactive oxygen species accumulation and decreased mitochondrial membrane potential, whereas decreased calcium concentrations caused by GsMTx4 and PIEZO1 knockdown had the opposite effect. Mechanistically, molecules in the NLRP3 pathway were activated in patients with CD and HT29 cells were stimulated by lipopolysaccharide; these effects were reversed by the knockdown of PIEZO1. Finally, PIEZO1 and NLRP3 knockdown decreased proinflammatory cytokine levels in HT29 cells. Conclusions: PIEZO1 in intestinal epithelial cells caused calcium influx, which resulted in mitochondrial dysfunction and activated the NLRP3 inflammasome, mediating intestinal inflammation.

Background: Intestinal barrier dysfunction and persistent inflammatory response are key pathophysiologic features of ulcerative colitis (UC). High mobility group box‐1 protein (HMGB1), an important inflammatory mediator and immunomodulatory factor, has been shown to be involved in the pathogenesis of UC. However, the association between HMGB1 and intestinal barrier dysfunction is unclear. Methods: In this study, we investigated the mechanism of HMGB1 driving intestinal barrier damage by integrating clinical data, animal models, and cellular experiments in UC. First, HMGB1 levels and its correlation with intestinal barrier protein expression in UC patients were verified based on Gene Expression Omnibus (GEO) dataset GSE75214 analysis and western blotting (WB) assay. Subsequently, colitis was induced in C57BL/6J mice using dextran sodium sulfate (DSS) and intervened with dipotassium glycyrrhizinate (DPG), and the effects of HMGB1 on colonic inflammation, ferroptosis, and intestinal barrier were assessed by histopathological scoring, qRT‐PCR, enzyme‐linked immunosorbent assay (ELISA), WB assay, immunofluorescence, and transmission electron microscopy (TEM) examination. Lastly, the influence of HMGB1 on ferroptosis‐related genes expression, TLR4/NF‐κB/GPX4 pathway activation and intestinal barrier damage were revealed by transepithelial electrical resistance (TEER) value measures, FITC‐dextran permeability detections, qRT‐PCR, and WB assays in vitro Caco‐2 cell models. Results: HMGB1 expression was significantly elevated in colonic tissues of UC patients (especially in active stage), and was negatively correlated with barrier protein expression. In DSS‐induced colitis mouse model, HMGB1 upregulation accompanied by changes in TLR4, NF‐κB, and GPX4 expression and ferroptosis‐related genes upregulation, while inhibition of HMGB1 attenuated inflammation, restored barrier function, and reversed ferroptosis. Moreover, cellular experiments further confirmed HMGB1 induced ferroptosis and intestinal barrier damage in Caco‐2 cells via the TLR4/NF‐κB/GPX4 pathway. Conclusion: Our results suggest that HMGB1 drives ferroptosis through the TLR4/NF‐κB/GPX4 signaling pathway, thereby exacerbating intestinal inflammation and barrier damage in UC. Targeting this pathway may provide a novel therapeutic strategy for UC.

Data from single-center experience or small sample-sized studies have shown that chromoendoscopy (CE) might be superior to white-light endoscopy (WLE) for dysplasia surveillance in ulcerative colitis (UC) patients. We performed a prospective randomized trial with a long-term follow-up to compare the detection rate of dysplasia among WLE with targeted biopsies (WLT), WLE with random biopsies (WLR), and dye-based CE with targeted biopsies (CET) in UC patients. Patients with long-standing UC were enrolled from 11 medical centers from March 2012 to December 2013 and randomized into three arms (WLT, WLR, and CET). Only high-definition endoscopy was used in all three groups. The patients were followed up by annual endoscopy with biopsies through December 2017. With a median follow-up time of 55 months, a total of 122 patients with 447 colonoscopies were finally analysed in the per-protocol set: WLT (n = 43), WLR (n = 40), and CET (n = 39). A total of 34 dysplastic lesions were found in 29 colonoscopies of 21 patients. WLR and CET could identify more colonoscopies that diagnosed dysplasia than WLT (8.1% and 9.7% vs 1.9%; P = 0.014 and 0.004, respectively). WLR obtained more biopsied samples than WLT and CET (16.4 ± 5.1 vs 4.3 ± 1.4 and 4.3 ± 1.4; both P < 0.001). During the second half of the follow-up (37 − 69 months), CET could identify more colonoscopies that diagnosed dysplasia than WLT (13.3% vs 1.6%, P = 0.015) and showed a trend for increasing the detection rate compared with WLR (13.3% vs 4.9%, P = 0.107). For a better outcome of cancer/dysplasia surveillance in patients with long-standing UC, CET appeared to be more effective than WLT and less tedious than WLR. CET was found to be particularly useful when a long-term (>3 years) follow-up was conducted for dysplasia surveillance. The trial was registered on www.chictr.org.cn (ChiCTR1900023689).