Exploring the relationship between urinary phthalate metabolites and Crohn's disease via oxidative stress, and the potential moderating role of gut microbiota: A conditional mediation model.

OBJECTIVE: Interactions between phthalic acid esters (PAEs) exposure and Crohn's disease (CD) were unknown. This study aims to examine the association between exposure to PAEs and CD activity and to explore the roles of oxidative stress and microbiota. METHODS: A cross-sectional study with 127 CD patients was conducted. The disease activity was evaluated based on symptoms (Harvey-Bradshaw index, HBI), endoscopy findings (Simple Endoscopic Score for CD, SES-CD), and computed tomography enterography (CTE-scores). Ten urinary PAEs metabolites (mPAEs), two urinary oxidative stress biomarkers, including 8-hydroxydeoxyguanosine (8-OHdG) and 8-iso-prostaglandin-F2α (8-iso-PGF2α), as well as 16S rRNA sequencing of stool samples were determined. Multiple linear regression models and Hayes's PROCESS macro for SPSS were used to evaluate the interplays between urinary PAEs metabolites, CD activities, oxidative stress, and microbiota diversity. RESULTS: There were positive associations between most mPAEs and HBI. Oxidative stress mediated 20.69-89.29% of the indirect associations between low molecular weight (LMW) mPAEs and HBI, while the majority of the high molecular weight (HMW) mPAEs were directly associated with HBI. In addition, microbiota diversity moderated the indirect associations of LMW mPAEs on HBI. CONCLUSIONS: PAEs exposure was related to CD activity, and the association could be mediated by oxidative stress and reversed or alleviated by rich gut microbiota.

Resolvin D1 ameliorates hepatic steatosis by remodeling the gut microbiota and restoring the intestinal barrier integrity in DSS-induced chronic colitis.

BACKGROUND AND PURPOSE: The maintenance of intestinalmucosalbarrier function plays an important role in hepatic steatosis. Increasing evidence has shown that resolvin D1 (RVD1) exerts a potential effect on hepatic steatosis. The aims of this study were to explore the mechanisms of RVD1 on hepatic steatosis based on the gut-liver axis and intestinal barrier function. EXPERIMENTAL APPROACH: We established a DSS-induced chronic colitis model to evaluate hepatic steatosis. RVD1 was administered i.p. during the last 4 weeks. The colon and liver samples were stained with hematoxylin and eosin for histopathological analysis. The expression levels of intestinal tight junction genes and inflammatory genes were determined by quantitative PCR. The serum levels of glucose, cholesterol, triglycerides and LPS were measured, and the gut microbiota was analyzed by 16S rRNA gene sequencing. KEY RESULTS: RVD1 prevented weight loss, histopathological changes, and elevated levels of inflammatory cytokines. Moreover, RVD1 administration attenuated DSS-induced hepatic steatosis and inflammatory responses in mice. In addition, RVD1 improved intestinal barrier function by increasing levels of tight junction molecules and decreasing the plasma LPS levels. The RVD1-treated mice also showed a different gut microbiota composition compared with found in the mice belonging to the DSS group but similar to that in normal chow diet-fed mice. CONCLUSIONS AND IMPLICATIONS: RVD1 treatment ameliorates DSS-induced hepatic steatosis by ameliorating gut inflammation, improving intestinal barrier function and modulating intestinal dysbiosis.

Resolvin D1 Prevents Epithelial-to-Mesenchymal Transition and Reduces Collagen Deposition by Stimulating Autophagy in Intestinal Fibrosis.

BACKGROUND: Intestinal fibrosis is the most common complication of inflammatory bowel disease; nevertheless, specific therapies are still unavailable. Resolvin D1 (RvD1), a typical endogenous ω-3 fatty acid-derived lipid mediator, has attracted wide attention due to its remarkable anti-fibrosis effects. However, the efficacy and mechanisms of RvD1 in intestinal fibrosis remain unclear. AIM: To investigate the protective effect of RvD1 in a dextran sulfate sodium (DSS)-induced intestinal fibrosis model and explore the molecular mechanisms underlying its anti-fibrotic effect. METHODS: A DSS-induced intestinal fibrosis model and intestinal epithelial-to-mesenchymal transition (EMT) model were used to observe the efficacy of RvD1, and fibroblasts were stimulated with conditioned medium with or without TGF-ß1 to investigate the probable mechanisms of RvD1 in intestinal fibrosis disease. RESULTS: Intestinal fibrosis was effectively alleviated by RvD1 in a DSS-induced model, both preventively and therapeutically, and autophagy inhibition-induced EMT in intestinal epithelial cells was significantly suppressed in vivo and in vitro. Furthermore, RvD1 reduced epithelial cell EMT paracrine signaling, which promoted the differentiation of local fibroblasts into myofibroblasts. CONCLUSIONS: Our results suggested that RvD1 reduces autophagy-induced EMT in intestinal epithelial cells and ameliorates intestinal fibrosis by disrupting epithelial-fibroblast crosstalk.

Analytical modeling framework for performance degradation of PEM fuel cells during startup-shutdown cycles.

Startup-shutdown cycling is one of the main factors that contribute to fuel cell deterioration related to high cathode potential. In this study, a coupled model with the carbon corrosion model and agglomerate model of the cathode catalyst layer is built to predict performance degradation during startup-shutdown cycles. The carbon corrosion model calculates the carbon loading loss through the rate equations and material balance expressions of seven reactions, while the agglomerate model describes the catalyst layer performance according to the computed structural parameters. A set of operational and structural parametric studies are used to investigate their effects on initial performance and voltage degradation rate. The maximum voltage of the cyclic load is found to have a greater influence over the voltage degradation rate compared with relative humidity, pressure, and minimum voltage of the cyclic load. Among the structural parameters, the carbon loading and platinum loading have the greatest and least impact on voltage degradation rate, respectively, while ionomer fraction has a complex and nonmonotonic effect. An optimal design strategy is provided with a case demonstration. Results may provide a fundamental and important tool for degradation prediction in startup-shutdown conditions and guidance for catalyst layer design and operation.