Mycophenolate mofetil (MMF) is one of the most used immunosuppressive drugs in organ transplantation, but frequent gastrointestinal (GI) side effects through unknown mechanisms limit its clinical use. Gut microbiota and its metabolites were recently reported to play a vital role in MMF-induced GI toxicity, but the specific mechanism of how they interact with the human body is still unclear. Here, we found that secondary bile acids (BAs), as bacterial metabolites, were significantly reduced by MMF administration in the gut of mice. Microbiome data and fecal microbiota transfer model supported a microbiota-dependent effect on the reduction of secondary BAs. Supplementation of the secondary BA lithocholic acid (LCA) alleviated MMF-induced weight loss, colonic inflammation, and oxidative phosphorylation damage. Genetic deletion of the vitamin D3 receptor (VDR), which serves as a primary colonic BA receptor, in colonic epithelial cells (VDR^ΔIEC) abolished the therapeutic effect of LCA on MMF-induced GI toxicity. Impressively, we discovered that paricalcitol, an FDA-approved VDR agonist that has been used in clinics for years, could effectively alleviate MMF-induced GI toxicity. Our study reveals a previously unrecognized mechanism of gut microbiota, BAs, and VDR signaling in MMF-induced GI side effects, offering potential therapeutic strategies for clinics.

Acute pancreatitis is a rare complication in postoperative colorectal cancer patients after FOLFOX6 (oxaliplatin + calcium folinate +5-FU [5-fluorouracil]) chemotherapy. In this paper, a total of 62 patients with gastrointestinal cancer were observed after the burst of acute pancreatitis. Surgery of the 62 cases of colorectal cancer patients was completed successfully. But when they underwent FOLFOX6 chemotherapy, five patients got acute pancreatitis (8.06%), four (6.45%) had mild acute pancreatitis, and one (1.61%) had severe acute pancreatitis, of which two were males (3.23%) and three females (4.84%). No patients (0.00%) had acute pancreatitis on the 1st day after chemotherapy; one patient (1.61%) got it in the first 2 and 3 days after chemotherapy; and three others (4.83%) got it in the first 4 days after chemotherapy. In the 62 patients with malignant tumors, the body mass index (BMI) was less than 18 (underweight) in six of them, with two cases of acute pancreatitis (33.33%); the BMI was 18–25 (normal weight) in 34 cases, with one case (2.94%) of acute pancreatitis; the BMI was 25–30 (overweight) in 13 cases, with 0 cases (0.00%) of acute pancreatitis; and the BMI was ≥30 (obese) in nine patients, with two cases of acute pancreatitis (22.22%). After symptomatic treatment, four patients were cured and one died; the mortality rate was 1.61%. Most of them appeared in the first 4 days after chemotherapy; the probability of this complication is significantly higher in slim and obese patients than in normal weight patients. Postoperative colorectal cancer patients after FOLFOX6 chemotherapy have a sudden onset of acute pancreatitis occult, especially in patients with severe acute pancreatitis; the symptoms are difficult to control, there is high mortality and it is worthy of clinician’s attention.

Excessive consumption of ultra-processed foods (UPFs) containing non-nutritive sweeteners (NNS) has been implicated in inflammatory bowel disease (IBD), yet the effects of erythritol on intestinal inflammation remain poorly understood. In this study, we assessed NNS-containing UPF exposure in patients with IBD and healthy controls, and then investigated the effects of erythritol in a dextran sulfate sodium (DSS)-induced colitis. Food frequency questionnaire (FFQ) results showed that patients with IBD, particularly those with active disease, had a higher proportion of NNS-containing UPF categories among total UPFs consumed. In mice, erythritol administration exacerbated DSS-induced colitis, as evidenced by sustained body weight loss, increased disease activity index, impaired intestinal barrier integrity, and elevated inflammatory cytokine expression. Transcriptomic analysis revealed significant enrichment of ferroptosis-related pathways in the colonic mucosa of erythritol-treated colitic mice. Furthermore, erythritol markedly altered gut microbial composition, characterized by increased abundance of potentially pathogenic bacteria and enrichment of Alistipes sp. CHKCI003. Untargeted metabolomics demonstrated alteration of tryptophan metabolism. Consistently, erythritol aggravated depression-like behavior in DSS-induced mice. Collectively, these findings suggest that erythritol exacerbates experimental colitis and depression-like behavior, potentially through microbiota dysbiosis, ferroptosis-associated alterations, and disrupted tryptophan metabolism.