2'-Fucosyllactose promotes Lactobacillus rhamnosus KLDS 8001 to repair LPS-induced damage in Caco-2 cells

Phase-dependent iron depletion differentially regulates the niche of intestinal stem cells in experimental colitis via ERK/STAT3 signaling pathway

Introduction

Ulcerative colitis (UC) is a global gastrointestinal disease, which is mainly caused by both dysfunctional epithelial barrier and inflammation response. Iron is a critical fundamental element for both the maintenance of homeostasis and the mediation of inflammation in many tissues. However, the role and mechanism of iron in the phase of enteritis and the subsequent repairing phase of intestinal stem cells has not been elucidated. In this study, we aimed to explore whether and how iron depletion would affect the occurrence and outcome of experimental colitis.

Methods

Iron depletion was realized by deferoxamine (DFO) at either the early stage or late stage of dextran sulfate sodium (DSS) induced experimental colitis in mice. The gross images of colons, general health, histology, barrier integrity, and qRT-PCR were performed. Meanwhile, cell culture and colonic organoids were used to examine the influence of iron depletion in vitro. Signaling pathway and inflammatory infiltration were investigated by immunostaining.

Results

Iron depletion within the early stage of DSS treatment significantly inhibited the onset of the inflammatory response, maintained the integrity of the colonic epithelium, and preserved the activity of intestinal stem cells (ISCs) both in vivo and in vitro. However, both continuous iron depletion by DFO and late DFO treatment aggravated colonic injury and postponed the recovery from colitis. Early DFO-induced iron depletion was able to maintain the p-STAT3 and p-ERK1/2 signaling pathways within the colonic epithelium at the early phase of colitis, but late DFO treatment inhibited the activity of these two pathways.

Discussion

Our study demonstrated that the manipulation of iron depletion by DFO might greatly affect the outcomes of experimental colitis in a phase-dependent manner, which suggests that the balance of iron metabolism might be an effective therapeutic target for the clinical treatment of IBD patients.

The Human Milk Oligosaccharide 2′-Fucosyllactose Alleviates Liver Steatosis, ER Stress and Insulin Resistance by Reducing Hepatic Diacylglycerols and Improved Gut Permeability in Obese Ldlr-/-.Leiden Mice

Non-alcoholic fatty liver disease (NAFLD) is a complex multifactorial disorder that is associated with gut dysbiosis, enhanced gut permeability, adiposity and insulin resistance. Prebiotics such as human milk oligosaccharide 2′-fucosyllactose are thought to primarily improve gut health and it is uncertain whether they would affect more distant organs. This study investigates whether 2′-fucosyllactose can alleviate NAFLD development in manifest obesity. Obese hyperinsulinemic Ldlr-/-.Leiden mice, after an 8 week run-in on a high-fat diet (HFD), were treated with 2′-fucosyllactose by oral gavage until week 28 and compared to HFD-vehicle controls. 2′-fucosyllactose did not affect food intake, body weight, total fat mass or plasma lipids. 2′-fucosyllactose altered the fecal microbiota composition which was paralleled by a suppression of HFD-induced gut permeability at t = 12 weeks. 2′-fucosyllactose significantly attenuated the development of NAFLD by reducing microvesicular steatosis. These hepatoprotective effects were supported by upstream regulator analyses showing that 2′-fucosyllactose activated ACOX1 (involved in lipid catabolism), while deactivating SREBF1 (involved in lipogenesis). Furthermore, 2′-fucosyllactose suppressed ATF4, ATF6, ERN1, and NUPR1 all of which participate in endoplasmic reticulum stress. 2′-fucosyllactose reduced fasting insulin concentrations and HOMA-IR, which was corroborated by decreased intrahepatic diacylglycerols. In conclusion, long-term supplementation with 2′-fucosyllactose can counteract the detrimental effects of HFD on gut dysbiosis and gut permeability and attenuates the development of liver steatosis. The observed reduction in intrahepatic diacylglycerols provides a mechanistic rationale for the improvement of hyperinsulinemia and supports the use of 2′-fucosyllactose to correct dysmetabolism and insulin resistance.