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Background Exosomes derived from mesenchymal stem cells have shown therapeutic effects for colitis. As a more clinically accessible resource, the therapeutic potential of exosomes from adipose-derived stem cells (ASCs) has not been fully elucidated, and whether hypoxia precondition could improve the therapeutic effect of ASC-derived exosomes in colitis remains elusive. Methods In this study, exosomes were derived from ASCs under normoxia (NExos) and hypoxia (HExos) and were identified by detecting their morphology, size distribution, and exosome surface markers. The concentration of inflammation-related cytokines was detected by ELISA, and macrophage phenotype–related genes were determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence. A miRNA microarray sequencing analysis was conducted to confirm the differentially expressed miRNAs. Dextran sulfate sodium–induced colitis was employed as an in vivo assay. Results Administration of NExos alleviated inflammation by modulating the balance of macrophages both in cellular assays and in vivo experiments, and HExos showed higher therapeutic efficiency than NExos. The miR-216a-5p in HExos was significantly enriched and promoted macrophage M2 polarization through transfer to macrophages by exosomes. The miR-216a-5p was confirmed to target the 3’-UTR of HMGB1. Mechanistically, hypoxia-induced ASCs release miR-216a-5p in an exosomal way that induced macrophage M2 polarization by regulating the HMGB1/TLR4/NF-κB signaling pathway. Conclusions Exosomal miR-216a-5p released from hypoxia-prime ASCs showed higher therapeutic efficiency than NExos in experimental colitis by promoting the M2 macrophage phenotype, which indicated that hypoxia prime may represent a promising approach to optimizing the function of ASC-derived exosomes.

Background An excessive postoperative inflammatory response is common after surgery for inflammatory bowel disease (IBD) and may be associated with an increased incidence of postoperative ileus. This study assessed the role of perioperative dexamethasone in postoperative ileus after IBD surgery. Method Patients undergoing elective IBD surgery were randomized to either an intravenous 8-mg dose of dexamethasone (n = 151) or placebo (n = 151) upon induction of anesthesia. The primary outcome was the incidence of prolonged postoperative ileus. Secondary outcomes included incidence of reported nausea or vomiting, time to first passage of flatus and stool, GI-2 recovery, postoperative pain, length of stay, and surgical complications. Results An intention-to-treat analysis revealed that patients who received dexamethasone exhibited a lower incidence of prolonged postoperative ileus (22.5% vs 38.4%; P = 0.003), shorter time to first passage of stool (28 vs 48 h, P Conclusion A single, intravenous 8-mg dose of dexamethasone upon induction of anesthesia reduced the incidence of prolonged postoperative ileus, the intensity of postoperative pain, and shortened the postoperative length of stay for IBD patients undergoing elective surgery. ClinicalTrials.gov: NCT03456752.

Background Although the interaction between gut microbiota and pouchitis after ileal pouch anal anastomosis (IPAA) for ulcerative colitis (UC) has been confirmed, evidence of commensal mycobiota in the etiology of pouchitis is still lacking. This study aimed to investigate the role of fungi in the pathogenesis of pouchitis. Methods Fecal samples were collected from UC patients with or without pouchitis after IPAA. Experimental pouchitis was induced by 5% dextran sulfate sodium for 7 consecutive days in a rat model of IPAA. Fungal dysbiosis was induced by 0.5% fluconazole (Flu), and commensal fungal recognition through dectin-1 was blocked by 5% laminarin. Fecal fungal composition was analyzed using internal transcribed spacer 2 sequencing. Severity of pouchitis and activation of the CARD9-nuclear factor kappa-B pathway was determined among different groups. Results Patients with pouchitis had a lower alpha (α) diversity in mycobiota composition and a higher abundance of Saccharomyces at the genus level compared with those with a normal pouch. In the rat model of pouchitis, Flu treatment decreased fungal burden but induced fungal dysbiosis, characterized by increased α diversity, a decreased relative abundance of Kazachstania, and increased Polythrincium and Saccharomyces. In addition, Flu treatment worsened dextran sulfate sodium pouchitis, as indicated by increased mortality, weight loss, higher histological score, and CD4+ cell infiltration. Laminarin also increased the severity of pouchitis. In the Flu and laminarin groups, the expression of interferon-γ, tumor necrosis factor-α, CARD9, and phosphorylated nuclear factor kappa-B inhibitor alpha was decreased. Conclusions Patients with pouchitis had altered fungal composition. Fungal dysbiosis or recognition deficiency by the host may exacerbate experimental pouchitis. Strategies targeting commensal mycobiota may provide therapeutic potential against pouchitis, especially for antibiotic-refractory patients.

Background Malnutrition is prevalent among patients with inflammatory bowel disease (IBD). Nutritional profiles among Asian patients with IBD have seldom been investigated. We assessed the prevalence of and risk factors for malnutrition, use of nutrition support, and sociopsychological status associated with malnutrition among patients with IBD in China. Methods Patients with ulcerative colitis and Crohn’s disease (CD) recruited from 43 tertiary referral hospitals were screened for malnutrition and nutrient deficiencies in this cross-sectional study. The use of nutrition support was recorded. The sociopsychological status was assessed by subjective questionnaires. Factors associated with malnutrition were analyzed, and multivariate regression was used to determine independent predictors for malnutrition. Results We recruited 1013 patients with a median age of 35.0 years, 58.5% of them had CD, and 61.4% of all patients were male. Overall, 49.5% (n = 501) of patients were diagnosed with malnutrition, including 57.0% of patients with CD, 38.8% of patients with ulcerative colitis, and 44.1% of patients with quiescent or mildly active disease. Nutrient deficiencies were prevalent despite the absence of malnutrition. Malnutrition was associated with adverse sociopsychological status, including decreased social support, higher perceived stress, and impaired quality of life. Moderate to severe disease activity and extensive disease were 2 independent risk factors for malnutrition. In total, 41.6% of patients received nutrition support, and patients with risk factors were more likely to receive nutrition support. Conclusions Malnutrition was highly prevalent and associated with adverse consequences in Chinese patients with IBD. Malnutrition screening and early initiation of nutrition support are essential components in IBD care.

BACKGROUND The role of interleukin-6 (IL-6) in the prediction of intra-abdominal septic complications (IASCs) in patients with Crohn's disease (CD) remains unclear. We assessed the serum IL-6 time course and its association with postoperative IASCs in patients undergoing elective intestinal operations for CD. METHODS In total, 118 patients who underwent intestinal operations for CD were prospectively evaluated. They were divided into an IASC group and non-IASC group. Multivariate analyses were used to identify risk factors, and receiver operating characteristic curve analysis was performed. RESULTS Multivariate analysis showed that a high IL-6 concentration of >137.25 pg/mL on postoperative day (POD) 1 was independently associated with IASCs (odds ratio, 5.74; 95% confidence interval [CI], 1.46-22.67; P = 0.012) and a longer postoperative length of hospitalization (6 vs 9 days, P < 0.001). The median interval between surgery and IASCs (interquartile range) was 6 (4-22) days, and the IL-6 concentration was significantly different between patients with and without IASCs on PODs 1, 3, and 5. The ideal IL-6 cutoff value on POD 1 for the prediction of postoperative IASCs was 137.25 pg/mL, yielding a sensitivity of 81%, specificity of 58%, and area under the curve of 0.71 (95% CI, 0.59-0.83), with a negative predictive value of 0.93. CONCLUSIONS A high IL-6 concentration on POD 1 is independently associated with the occurrence of postoperative IASCs in patients undergoing elective surgery for CD and could allow for earlier diagnosis and earlier intervention for IASCs compared with C-reactive protein.

Crohn's disease (CD) is a complex gastrointestinal disorder involving multiple levels of cross talk between the immunological, neural, vascular, and endocrine systems. The current dominant theory in CD is based on the unidirectional axis of dysbiosis-innate immunity-adaptive immunity-mesentery-body system. Emerging clinical evidence strongly suggests that the axis be bidirectional. The morphologic and/or functional abnormalities in the mesenteric structures likely contribute to the disease progression of CD, to a less extent the disease initiation. In addition to adipocytes, mesentery contains nerves, blood vessels, lymphatics, stromal cells, and fibroblasts. By the secretion of adipokines that have endocrine functions, the mesenteric fat tissue exerts its activity in immunomodulation mainly through response to afferent signals, neuropeptides, and functional cytokines. Mesenteric nerves are involved in the pathogenesis and prognosis of CD mainly through neuropeptides. In addition to angiogenesis observed in CD, lymphatic obstruction, remodeling, and impaired contraction maybe a cause and consequence of CD. Lymphangiogenesis and angiogenesis play a concomitant role in the progress of chronic intestinal inflammation. Finally, the interaction between neuropeptides, adipokines, and vascular and lymphatic endothelia leads to adipose tissue remodeling, which makes the mesentery an active participator, not a bystander, in the disease initiation and precipitation CD. The identification of the role of mesentery, including the structure and function of mesenteric nerves, vessels, lymphatics, and fat, in the intestinal inflammation in CD has important implications in understanding its pathogenesis and clinical management.

Background Mesenteric fat wrapping and thickening are typical characteristics of Crohn's disease (CD). The purpose of this study was to explore the cause of mesenteric adipose hypertrophy and analyze the role of lymphatic vessels in mesenteric adipose tissue in CD. Methods Twenty-three CD patients who underwent ileocolonic resection were included. In CD patients, specimens were obtained from hypertrophic mesenteric adipose tissue (htMAT) next to the diseased ileum. The mesenteric lymphatic vessels in mesenteric adipose tissue were separated under stereoscope microscope. Transmission electron microscopy and immunofluorescence were used to observe the structure of mesenteric lymphatic vessels. The NF-κB signaling pathway in mesenteric adipose tissue was detected in CD specimens using Western blotting. Results Electron microscopy showed that the structure of mesenteric lymphatic vessel was discontinuous, and the microstructure of lymphatic endothelial cells appeared ruptured and incomplete. Through an immunofluorescence technique, we found that the surface of lymphatic endothelial cells lacked tight junction protein staining in CD. Also, the expression of claudin-1, occludin, and ZO-1 in the mesenteric lymphatic vessel of htMAT was significantly lower than that of control. These results indicated that the structure of the mesenteric lymphatic vessel in htMAT was mispatterned and ruptured, which could lead to lymph leakage. Leaky lymph factors could stimulate adipose tissue to proliferate. Antigens that leaked into the mesenteric adipose tissue could effectively elicit an immune response. The levels of cytokines (TNF-a, IL-1β, IL-6) was increased in the htMAT of CD patients by activated NF-κB signaling pathway. Conclusions Our findings demonstrated that the hypertrophy of mesenteric adipose tissue may result from mispatterned and ruptured lymphatic vessels. Alteration of mesenteric adipose tissue was associated with activated NF-κB signaling pathway. This study enhances support for elucidating the importance of mesenteric lymphatic vessels and adipose tissue in CD.

BACKGROUND Mesenteric fat plays an important role in the pathogenesis of Crohn's disease (CD), and a higher ratio of visceral fat area (VFA) to subcutaneous fat area (SFA) is related to complicated disease status. Exclusive enteral nutrition (EEN) is an effective treatment option for patients with CD, and the aims of this study were to assess the effects of EEN on abdominal fat in patients with CD. METHODS Patient data were obtained from a prospectively maintained database. The SFA and VFA were measured in 38 patients with CD before and after 8-week EEN therapy, and the mesenteric fat index (MFI), defined as the ratio of VFA to SFA, was calculated. The correlations between MFI and CD activity index and C-reactive protein level were also evaluated. RESULTS The median age of the patients in our study was 29 years, and the median duration of disease was 3.05 years. Both VFA (P = 0.029) and MFI (P = 0.021) were significantly decreased in patients after EEN, but no significant change was observed in SFA (P = 0.335). MFI was significantly correlated with CD activity index (r = 0.523, P = 0.001) and C-reactive protein (r = 0.634, P < 0.0001) in patients with active CD before EEN, although no positive correlations were observed in patients after EEN treatment. CONCLUSIONS EEN induction therapy was associated with a significant decrease in VFA in patients with CD, and MFI was significantly correlated with CD activity index and C-reactive protein in active CD. Thus, our data reveal additional beneficial therapeutic mechanisms of enteral nutrition treatment in CD.

BACKGROUND Abnormalities in mesenteric adipose tissue (MAT) have long been recognized; however, the functional changes in the mesenteric adipocytes as well as the underlying mechanisms are not entirely clear. The aim of this study was to analyze the function and morphology of the MAT in patients with Crohn's disease (CD) and the underlying mechanism. METHODS The MAT specimens were obtained from areas adjacent to the intestinal wall in patients with CD (n = 33) and without CD (control, n = 23) who underwent intestinal resection. For patients with CD, paired samples were obtained from the macroscopically hypertrophic mesenteric adipose tissue (htMAT), adjacent to the involved ileum, and the macroscopically normal mesenteric adipose tissue (nMAT), contiguous with the healthy segment of the ileum. Morphological and molecular techniques were used to detect the characteristics of the MAT of CD and compare them with the characteristics of the control tissues. Hypoxia was confirmed by a high expression of hypoxia-inducible factor 1α. RESULTS The function and morphology of the nMAT in patients with CD were similar to those of the control tissues. htMAT of CD was dysfunctional based on the evidence that htMAT exhibited decreased lipid store, fatty acid synthase, and adipose triglyceride lipase, but increased levels of glucose transporter 1, aldolase C, and lactate when compared with those from nMAT and control tissues (P < 0.01). In addition, the structure of htMAT was found to be disorganized and characterized by higher levels of collagen content, interleukin 1β, interleukin 6, tumor necrosis factor α, and MCP-1 when compared with nMAT and control tissues (P < 0.01). htMAT was in a hypoxic condition, based on the findings that htMAT had a higher level of hypoxia-inducible factor 1α and a decreased number of vessels per adipocyte compared with those of nMAT and the control tissues (P < 0.01). The transforming growth factor β/Smad and nuclear factor-kappa B signaling pathways were found to be activated in htMAT, which may be associated with hypoxia. CONCLUSIONS The disorganized structure and dysfunction of mesenteric adipocyte tissue in CD was confirmed, and these alterations may be associated with hypoxia. It is possible that amelioration of mesenteric adipocyte hypoxia may help attenuate CD with underlying MAT inflammation.