polysaccharides alleviate ER stress in 5-FU-induced intestinal epithelial injury and mucositis via ARRB1 modulation.

polysaccharides (ATPS) were investigated for their protective effects against 5-fluorouracil (5-FU)-induced intestinal mucositis in intestinal epithelial cell 6 (IEC-6) cells and a murine model, with a focus on the role of β-arrestin1 (ARRB1) in endoplasmic reticulum stress (ERS) suppression. The study evaluated cell viability, apoptosis, inflammatory cytokine secretion (interleukin-1β, interleukin-6, tumor necrosis factor-α), and lactate dehydrogenase (LDH) release in IEC-6 cells, whereas diarrhea severity, body weight loss, intestinal histopathology, and tight junction protein expression were assessed in C57BL/6 mice. Western blot, immunohistochemistry, and transmission electron microscopy were used to investigate the underlying mechanisms of ATPS-mediated ERS inhibition. ATPS significantly improved cell survival and proliferation, reduced inflammatory cytokines and apoptosis, alleviated diarrhea severity, mitigated weight loss, and preserved intestinal barrier integrity by upregulating tight junction protein. Mechanistically, ATPS suppressed ERS activation by reducing glucose-regulated protein 78 (GRP78), phosphorylated protein kinase R-like endoplasmic reticulum kinase (p-PERK), phosphorylated eukaryotic translation initiation factor 2α subunit (p-eIF2α), and C/EBP homologous protein (CHOP) expression, effects that were significantly attenuated in ARRB1-knockdown IEC-6 cells and mice, indicating that ARRB1 is essential for ATPS-mediated ERS suppression and intestinal protection. These findings suggest that ATPS protects against 5-FU-induced intestinal mucositis by modulating ARRB1 and inhibiting ERS, highlighting its potential as a novel therapeutic strategy for chemotherapy-induced intestinal injury. This study provides new insights into the therapeutic potential of ATPS in alleviating 5-FU-induced intestinal mucositis by modulating ARRB1 and suppressing ERS. The protective effects of ATPS were validated in both IEC-6 cells and a murine model, demonstrating its ability to enhance intestinal barrier integrity, inhibit apoptosis, and reduce inflammation. These findings suggest that ARRB1-mediated ERS suppression is a critical mechanism underlying ATPS-induced intestinal protection, presenting a novel strategy for mitigating chemotherapy-induced gastrointestinal toxicity.