5-Aminosalicylic acid (5-ASA) is a first-line agent in both remission and maintenance therapy for ulcerative colitis (UC). However, the mucosal concentration of 5-ASA was significantly lower in patients with severe histological inflammation, which further led to a poor response to 5-ASA treatment. Our study aimed to clarify the mechanism of 5-ASA uptake into colonic epithelial cells and to further explore the reason for the decreased colonic mucosal 5-ASA concentration in UC patients. Our results demonstrated that the colonic 5-ASA concentration was notably reduced in DSS-induced colitis mice and inversely correlated with colonic inflammation. 5-ASA was not a substrate of carnitine/organic cation transporter 1/2 (OCTN1/2) or multidrug resistance protein 1 (MDR1), whereas organic anion transporting polypeptide 2B1 (OATP2B1) and sodium-coupled monocarboxylate transporter 1 (SMCT1) mediated the uptake of 5-ASA, with a greater contribution from OATP2B1 than SMCT1. Inhibitors and siRNAs targeting OATP2B1 significantly reduced 5-ASA absorption in colonic cell lines. Moreover, OATP2B1 expression was dramatically downregulated in colon tissues from UC patients and dextran sodium sulfate (DSS)-induced colitis mice, and was also negatively correlated with colonic inflammation. Mechanistically, mixed proinflammatory cytokines downregulated the expression of OATP2B1 in a time- and concentration-dependent manner through the hepatocyte nuclear factor 4 α (HNF4α) pathway. In conclusion, OATP2B1 was the pivotal transporter involved in colonic 5-ASA uptake, which indicated that inducing OATP2B1 expression may be a strategy to promote 5-ASA uptake and further improve the concentration and anti-inflammatory efficacy of 5-ASA in UC.

Background/Aims: The aim of this study was to analyze the chronological changes in postoperative complications in surgical ulcerative colitis patients over the past decade in China and to investigate the potential parameters that contributed to the changes. Methods: Ulcerative colitis patients who underwent surgery during 2008-2017 were retrospectively enrolled from 13 hospitals in China. Postoperative complications were compared among different operation years. Risk factors for complications were identified by logistic regression analysis. Results: A total of 446 surgical ulcerative colitis patients were analyzed. Fewer short-term complications (24.8% vs. 41.0%, P = 0.001) and more laparoscopic surgeries (66.4% vs. 25.0%, P < 0.001) were found among patients who received surgery during 2014-2017 than 2008-2013. Logistic regression suggested that independent protective factors against short-term complications were a higher preoperative body mass index (odds ratio [OR], 0.870; 95% confidence interval [CI], 0.785-0.964; P = 0.008), laparoscopic surgery (OR, 0.391; 95% CI, 0.217-0.705; P = 0.002) and elective surgery (OR, 0.213; 95% CI, 0.067-0.675; P = 0.009). The chronological decrease in short-term complications was associated with an increase in laparoscopic surgery. Conclusions: Our data revealed a downward trend of short-term postoperative complications among surgical ulcerative colitis patients in China during the past decade, which may be due to the promotion of minimally invasive techniques among Chinese surgeons.

The rapid dissemination of antibiotic resistance accelerates the desire for new antibacterial agents. Here, a class of antimicrobial peptides (AMPs) is designed by modifying the structural parameters of a natural chickpea‐derived AMP–Leg2, termed “functionalized chickpea‐derived Leg2 antimicrobial peptides” (FCLAPs). Among the FCLAPs, KTA and KTR show superior antibacterial efficacy against the foodborne pathogen Escherichia coli ( E. coli ) O157:H7 (with MICs in the range of 2.5–4.7 µmol L −1 ) and demonstrate satisfactory feasibility in alleviating E. coli O157:H7‐induced intestinal infection. Additionally, the low cytotoxicity along with insusceptibility to antimicrobial resistance increases the potential of FCLAPs as appealing antimicrobials. Combining the multi‐omics profiling andpeptide‐membrane interaction assays, a unique dual‐targeting mode of action is characterized. To specify the antibacterial mechanism, microscopical observations, membrane‐related physicochemical properties studies, and mass spectrometry assays are further performed. Data indicate that KTA and KTR induce membrane damage by initially targeting the lipopolysaccharide (LPS), thus promoting the peptides to traverse the outer membrane. Subsequently, the peptides intercalate into the peptidoglycan (PGN) layer, blocking its synthesis, and causing a collapse of membrane structure. These findings altogether imply the great potential of KTA and KTR as promising antibacterial candidates in combating the growing threat of E. coli O157:H7.

BACKGROUND:Obesity is associated with an increased risk of developing Crohn's disease (CD), higher disease activity, and comparatively worse clinical outcomes.AIM:To investigate the role of mesenteric adipose tissue-derived exosomes in the pathogenesis of CD aggravation in obese individuals.METHODS:First, we induced colitis in mice initiated on high-fat and normal diets and compared the severity of colitis. We then extracted and identified exosomes from mesenteric adipose tissue and determined the levels of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in mesenteric adipose tissue-derived exosomes and the colon. Next, we demonstrated an interaction between MALAT1 and the miR-15a-5p/activating transcription factor 6 (ATF6) axis. Finally, we explored the effects of mesenteric adipose tissue-derived exosomes extracted from mice fed a high-fat or normal diet on the severity of 2,4,6-trinitrobe-nzenesulfonic acid (TNBS)-induced colitis and ATF6-related endoplasmic reticulum stress pathways.RESULTS:High-fat diet was found to aggravate TNBS-induced colitis in mice. The expression of MALAT1 in mesenteric adipose tissue-derived exosomes of high-fat diet-fed mice increased. The increased expression of MALAT1 in colon tissue exacerbated TNBS-induced colitis and activated the ATF6 endoplasmic reticulum stress pathway. This effect was partially reversed by the reduced expression of MALAT1 and overexpression of miR-15a-5p.CONCLUSION:Mesenteric adipose tissue-derived exosome-encapsulated long noncoding RNAs MALAT1 targets the colon and aggravates TNBS-induced colitis in obese mice, which may potentially act on the miR-15a-5p/ATF6 axis and activate endoplasmic reticulum stress.

BACKGROUND:Intestinal fibrosis is a common complication of Crohn's disease (CD) and is characterized by the excessive accumulation of extracellular matrix produced by activated myofibroblasts. Caveolin-1 (CAV1) inhibits fibrosis. However, limited data show that CAV1 affects intestinal fibrosis.METHODS:Human CD tissue samples were gained from patients with CD who underwent surgical resection of the intestine and were defined as stenotic or nonstenotic areas. A dextran sodium sulfate-induced mouse model of intestinal fibrosis was established. For in vitro experiments, we purchased CCD-18Co intestinal fibrosis cells and isolated and cultured human primary colonic fibroblasts. These fibroblasts were activated by transforming growth factor β administration for 48 hours. In the functional experiments, a specific small interfering RNA or overexpression plasmid was transfected into fibroblasts. The messenger RNA levels of fibrosis markers, such as α-smooth muscle actin, fibronectin, connective tissue growth factor, and collagen I1α, were determined using quantitative polymerase chain reaction. Western blot analysis was applied to detect the expression of CAV1, SQSTM1/p62 (sequestosome 1), and other fibrosis markers.RESULTS:In human CD samples and the dextran sodium sulfate-induced mouse model of intestinal fibrosis, we observed a downregulation of CAV1 in fibrosis-activated areas. Mechanistically, CAV1 knockdown in both human primary colonic fibroblasts and CCD-18Co cells promoted fibroblast activation, while CAV1 overexpression inhibited fibroblast activation in vitro. We found that SQSTM1/p62 positively correlated with CAV1 expression levels in patients with CD and that it was indirectly modulated by CAV1 expression. Rescue experiments showed that CAV1 decreased primary human intestinal fibroblast activation by inhibiting fibroblast autophagy through the modulation of SQSTM1/p62.CONCLUSIONS:Our data demonstrate that CAV1 deficiency induces fibroblast activation by indirectly regulating SQSTM1/p62 to promote fibroblast autophagy. CAV1 or SQSTM1/p62 may be potential therapeutic targets for intestinal fibrosis.

We previously showed that the vitamin D receptor (VDR) plays a crucial role in acute inflammatory bowel disease and that intestinal fibrosis is a common complication of Crohn's disease (CD). Epithelial-mesenchymal transition (EMT) is an important hallmark of fibrogenesis through which epithelial cells lose their epithelial phenotype and transform into mesenchymal cells. It is known that the VDR plays an essential role in epithelial integrity and mitochondrial function, but its role in intestinal fibrosis remains unknown. Here, we investigated whether the VDR is involved in epithelial mitochondrial dysfunction that results in EMT in intestinal fibrosis. Using human CD samples, intestine-specific VDR-KO mice, and fibroblast cellular models, we showed that the expression of the VDR was significantly lower in intestinal stenotic areas than in nonstenotic areas in patients with chronic CD. Genetic deletion of the VDR in the intestinal epithelium exacerbated intestinal fibrosis in mice administered with dextran sulfate sodium or 2,4,6-trinitrobenzene sulfonic acid, two experimental colitis inducers. In addition, we found that vitamin D dietary intervention regulated intestinal fibrosis by modulating the intestinal expression of the VDR. Mechanistically, knocking down the VDR in both CCD-18Co cells and human primary colonic fibroblasts promoted fibroblast activation, whereas VDR overexpression or VDR agonist administration inhibited fibroblast activation. Further analysis illustrated that the VDR inhibited EMT in the HT29 cell model and that mitochondrial dysfunction mediated epithelial integrity and barrier function in VDR-deficient epithelial cells. Together, our data for the first time demonstrate that VDR activation alleviates intestinal fibrosis by inhibiting fibroblast activation and epithelial mitochondria-mediated EMT.

Background: Gastrointestinal stromal tumor (GIST) is a common tumor that originates from mesenchyme in the alimentary system. Compared to the typical gastrointestinal carcinomas, GISTs exhibit unique malignant behaviors. Bioinformatic tools and subsequent experiments were applied to investigate novel targets involved in GIST progression and imatinib resistance. Methods: Differences of gene expression profiles between advanced and non-advanced GISTs were comprehensively analyzed based on Gene Expression Omnibus (GEO) dataset GSE136755. A protein-protein interaction (PPI) network was conducted to identify the potential target gene. Gene set enrichment analysis (GSEA) was used to elucidate relevant biological events of the target gene based on dataset GSE47911. Subsequently, immunohistochemistry and Kaplan-Meier analysis were performed to validate the prognostic value of the target gene in GISTs. Overexpression of the target gene was conducted to analyze its functions in proliferation, apoptosis, migration, and imatinib resistance of GIST/T1 cells. Results: In current study, a total of 606 differentailly expressed genes (DEGs) were screened based on dataset GSE136755 and the upregulated DEGs in advanced GISTs were mainly involved in cell division through functional annotations. The intersected hub gene, Aurora Kinase A (AURKA), was identified by degree and bottleneck algorithms. GSEA revealed that AURKA was involved in cell cycle-related biological processes. Oncomine and GEPIA databases supported an elevated expression pattern of AURKA in most human malignances. Clinical assay demonstrated that AURKA could be an independent prognostic factor for GISTs. Additionally, overexpression of AURKA was experimentally demonstrated to promote cell proliferation and survival, and enhance imatinib resistance of GIST/T1 cells. Conclusions: These findings indicated that overexpression of AURKA promoted GIST progression and enhanced imatinib resistance, implying the potential of AURKA as a therapeutic target for GISTs.

Inflammatory bowel diseases (IBD) are characterized by chronic relapsing disorders of the gastrointestinal tract. OCTN2 (SLC22A5) and its substrate l-carnitine (l-Car) play crucial roles in maintaining normal intestinal function. An aim of this study was to delineate the expression alteration of OCTN2 in IBD and its underlying mechanism. We also investigated the impact of OCTN2 on IBD progression and the possibility of improving IBD through OCTN2 regulation. Our results showed decreased OCTN2 expression levels and l-Car content in inflamed colon tissues of IBD patients and mice, which negatively correlated with the degree of colonic inflammation in IBD mice. Mixed proinflammatory cytokines TNF-α, IL-1β and IFNγ downregulated the expression of OCTN2 and subsequently reduced the l-Car content through PPARγ/RXRα pathways in FHC cells. OCTN2 silencing reduced the proliferation rate of the colon cells, whereas OCTN2 overexpression increased the proliferation rate. Furthermore, the ability of PPARγ agonist, luteolin, to increase OCTN2 expression resulted in the alleviation of colonic inflammatory responses. In conclusion, OCTN2 was downregulated in IBD by proinflammatory cytokines via the PPARγ/RXRα pathways, which reduced l-Car concentration and subsequently induced IBD deterioration. Upregulation of OCTN2 by the PPARγ agonist alleviated colonic inflammation. Our findings suggest that, OCTN2 may serve as a therapeutic target for IBD therapy.

The peptide/histidine transporter SLC15A3 is responsible for transporting histidine, certain dipeptide and peptidomimetics from inside the lysosome to cytosol. Previous studies have indicated that SLC15A3 transcripts are mainly expressed in the lymphatic system, however, its regulation and biological role in innate immune responses and inflammatory diseases are as yet unknown. In this study, mouse peritoneal macrophages (PMs), mouse bone marrow-derived macrophages (BMDMs), the human acute monocytic leukemia cell line THP-1 and the human lung epithelial carcinoma cell line A549 were used to investigate the regulation and biological role of SLC15A3 in TLR-mediated inflammatory responses. Our results showed that SLC15A3 was upregulated by TLR2, TLR4, TLR7 and TLR9 ligands in macrophages at both the mRNA and protein levels via activation of NF-κB (nuclear factor-kappa-B), MAPK (mitogen-activated protein kinase) and IRF3 (interferon regulatory factor 3). Furthermore, knockdown or overexpression of SLC15A3 influenced the TLR4-triggered expression of proinflammatory cytokines. A reporter gene assay showed that the SLC15A3 promotor contained potential NF-κB binding sites, which were reasonable for regulating SLC15A3 by TLR-activation through NF-κB signaling. Additionally, SLC15A3 expression was increased and positively related to inflammation in mice with bacterial peritonitis. The collective findings suggest that SLC15A3 is regulated by various TLRs, and that it plays an important role in regulating TLR4-mediated inflammatory responses.