Background & AimsHigh-fat diet (HFD) feeding is associated with gastrointestinal motility disorders. We recently reported delayed colonic motility in mice fed a HFD for 11 weeks. In this study, we investigated the contributing role of gut microbiota in HFD-induced gut dysmotility.MethodsMale C57BL/6 mice were fed a HFD (60% kcal fat) or a regular/control diet (RD) (18% kcal fat) for 13 weeks. Serum and fecal endotoxin levels were measured, and relative amounts of specific gut bacteria in the feces were assessed by real-time polymerase chain reaction. Intestinal transit was measured by fluorescent-labeled marker and a bead expulsion test. Enteric neurons were assessed by immunostaining. Oligofructose (OFS) supplementation with RD or HFD for 5 weeks also was studied. In vitro studies were performed using primary enteric neurons and an enteric neuronal cell line.ResultsHFD-fed mice had reduced numbers of enteric nitrergic neurons and showed delayed gastrointestinal transit compared with RD-fed mice. HFD-fed mice had higher fecal Firmicutes and Escherichia coli and lower Bacteroidetes compared with RD-fed mice. OFS supplementation protected against enteric nitrergic neuron loss in HFD-fed mice, and improved intestinal transit time. OFS supplementation resulted in a reduction in fecal Firmicutes and Escherichia coli and serum endotoxin levels. In vitro, palmitate activation of TLR4 induced enteric neuronal apoptosis in a Phospho–c-Jun N-terminal kinase–dependent pathway. This apoptosis was prevented by a c-Jun N-terminal kinase inhibitor and in neurons from TLR4-/- mice.ConclusionsTogether our data suggest that intestinal dysbiosis in HFD-fed mice contribute to the delayed intestinal motility by inducing a TLR4-dependent neuronal loss. Manipulation of gut microbiota with OFS improved intestinal motility in HFD mice.

The consumption of a high-fat diet (HFD) is associated with myenteric neurodegeneration, which in turn is associated with delayed colonic transit and constipation. We examined the hypothesis that an inherent increase in plasma free fatty acids (FFA) in the HFD together with an HFD-induced alteration in gut microbiota contributes to the pathophysiology of these disorders. C57BL/6 mice were fed a Western diet (WD) (35% kcal from fat enriched in palmitate) or a purified regular diet (16.9% kcal from fat) for 3, 6, 9 and 12 weeks. Gut microbiota dysbiosis was investigated by fecal lipopolysaccharide (LPS) measurement and metabolomics (linear trap quadrupole-Fourier transform mass spectrometer) analysis. Plasma FFA and LPS levels were assessed, in addition to colonic and ileal nitrergic myenteric neuron quantifications and motility. Compared to regular diet-fed control mice, WD-fed mice gained significantly more weight without blood glucose alteration. Dysbiosis was exhibited after 6 weeks of feeding, as reflected by increased fecal LPS and bacterial metabolites and concomitant higher plasma FFA. The numbers of nitrergic myenteric neurons were reduced in the proximal colon after 9 and 12 weeks of WD and this was also associated with delayed colonic transit. WD-fed Toll-like receptor 4 (TLR4) mice did not exhibit myenteric cell loss or dysmotility. Finally, LPS (0.5-2 ng·ml ) and palmitate (20 and 30 μm) acted synergistically to induce neuronal cell death in vitro, which was prevented by the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester. In conclusion, WD-feeding results in increased levels of FFA and microbiota that, even in absence of hyperglycaemia or overt endotoxaemia, synergistically induce TLR4-mediated neurodegeneration and dysmotility.

Objective: To systematically evaluate the prevalence of disclosed and undisclosed financial conflicts of interest (FCOI) among clinical practice guidelines (CPGs). Methods: In this systematic review, we ascertained the prevalence and types of FCOI for CPGs from January 1, 1980, to March 3, 2019. The primary outcome was the prevalence of FCOI among authors of CPGs. FCOI disclosures were compared between medical subspecialties and societies producing CPGs. Results: Among the 37 studies including 14,764 total guideline authors, 45% had at least one FCOI. The prevalence of FCOI per study ranged from 6% to 100%. More authors had FCOI involving general payments (39%) compared with research payments (29%). Oncology, neurology, and gastroenterology had the highest prevalence of FCOI compared with other medical specialties. Among the 8 studies that included the monetary values in US dollars of FCOI, average payments per author ranged from $578 to $242,300. Among the 10 studies that included data on undisclosed FCOI, 32% of authors had undisclosed industry payments. Conclusion: There are numerous FCOI among authors of CPGs, many of which are undisclosed. Our study found a significant difference in FCOI prevalence based on types of FCOI and CPG sponsor society. Additional research is required to quantify the implications of FCOI on clinical judgment and patient care.

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INTRODUCTION: De-escalation of biologic therapy is a commonly encountered clinical scenario. Although biologic discontinuation has been associated with high rates of relapse, the effectiveness of dose de-escalation is unclear. This review was performed to determine the effectiveness of dose de-escalation of biologic therapy in inflammatory bowel disease. METHODS: We searched EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials from inception to October 2019. Randomized controlled trials and observational studies involving dose de-escalation of biologic therapy in adults with inflammatory bowel disease in remission were included. Studies involving biologic discontinuation only and those lacking outcomes after dose de-escalation were excluded. Risk of bias was assessed using the Newcastle-Ottawa Scale. RESULTS: We identified 1,537 unique citations with 20 eligible studies after full-text review. A total of 995 patients were included from 18 observational studies (4 prospective and 14 retrospective), 1 nonrandomized controlled trial, and 1 subgroup analysis of a randomized controlled trial. Seven studies included patients with Crohn's disease, 1 included patients with ulcerative colitis, and 12 included both. Overall, clinical relapse occurred in 0%–54% of patients who dose de-escalated biologic therapy (17 studies). The 1-year rate of clinical relapse ranged from 7% to 50% (6 studies). Eighteen studies were considered at high risk of bias, mostly because of the lack of a control group. DISCUSSION: Dose de-escalation seems to be associated with high rates of clinical relapse; however, the quality of the evidence was very low. Additional controlled prospective studies are needed to clarify the effectiveness of biologic de-escalation and identify predictors of success.

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