Bile acid receptors regulate the metabolic and immune functions of circulating enterohepatic bile acids. This process is disrupted by administration of parenteral nutrition (PN), which may induce progressive hepatic injury for unclear reasons, especially in the newborn, leading to PN-associated liver disease. To explore the role of bile acid signaling on neonatal hepatic function, we initially observed that Takeda G protein receptor 5 (TGR5)-specific bile acids were negatively correlated with worsening clinical disease markers in the plasma of human newborns with prolonged PN exposure. To test our resulting hypothesis that TGR5 regulates critical liver functions to PN exposure, we used TGR5 receptor deficient mice (TGR5−/−). We observed PN significantly increased liver weight, cholestasis, and serum hepatic stress enzymes in TGR5−/− mice compared with controls. Mechanistically, PN reduced bile acid synthesis genes in TGR5−/−. Serum bile acid composition revealed that PN increased unconjugated primary bile acids and secondary bile acids in TGR5−/− mice, while increasing conjugated primary bile acid levels in TGR5-competent mice. Simultaneously, PN elevated hepatic IL-6 expression and infiltrating macrophages in TGR5−/− mice. However, the gut microbiota of TGR5−/− mice compared with WT mice following PN administration displayed highly elevated levels of Bacteroides and Parabacteroides, and possibly responsible for the elevated levels of secondary bile acids in TGR5−/− animals. Intestinal bile acid transporters expression was unchanged. Collectively, this suggests TGR5 signaling specifically regulates fundamental aspects of liver bile acid homeostasis during exposure to PN. Loss of TGR5 is associated with biochemical evidence of cholestasis in both humans and mice on PN. NEW & NOTEWORTHY Parenteral nutrition is associated with deleterious metabolic outcomes in patients with prolonged exposure. Here, we demonstrate that accelerated cholestasis and parental nutrition-associated liver disease (PNALD) may be associated with deficiency of Takeda G protein receptor 5 (TGR5) signaling. The microbiome is responsible for production of secondary bile acids that signal through TGR5. Therefore, collectively, these data support the hypothesis that a lack of established microbiome in early life or under prolonged parenteral nutrition may underpin disease development and PNALD.

Background and aims This is the first time that obesity and diabetes mellitus (DM) as protein conformational diseases (PCD) are reported in children and they are typically diagnosed too late, when β-cell damage is evident. Here we wanted to investigate the level of naturally-ocurring or real (not synthetic) oligomeric aggregates of the human islet amyloid polypeptide (hIAPP) that we called RIAO in sera of pediatric patients with obesity and diabetes. We aimed to reduce the gap between basic biomedical research, clinical practice-health decision making and to explore whether RIAO work as a potential biomarker of early β-cell damage. Materials and methods We performed a multicentric collaborative, cross-sectional, analytical, ambispective and blinded study; the RIAO from pretreated samples (PTS) of sera of 146 pediatric patients with obesity or DM and 16 healthy children, were isolated, measured by sound indirect ELISA with novel anti-hIAPP cytotoxic oligomers polyclonal antibody (MEX1). We carried out morphological and functional studied and cluster-clinical data driven analysis.

Activation of bile acid (BA) receptor, farnesoid X receptor (FXR) has been shown to inhibit inflammatory responses and improve tissue ischemia-reperfusion injury (IRI). This study investigated the effect of FXR deficiency on liver IRI, using a liver warm IRI mouse model. We demonstrate that liver IRI resulted in decreased FXR expression in the liver of WT mice. FXR -/mice displayed greater liver damage and inflammatory responses than WT mice, characterized by significant increases in liver weight, serum AST and ALT, hepatocyte apoptosis and liver inflammatory cytokines. Liver IRI increased expression of X box binding protein 1 (XBP1) and FGF21 in WT liver, but not in FXR -/liver, which conversely increased CHOP expression, suggesting a loss of ER stress protection in the absence of FXR. FXR deficiency increased circulating total BAs and altered BA composition with reduced TUDCA and hepatic BA synthesis markers. FXR deficiency also reshaped gut microbiota composition with increased Bacteroidetes and Proteobacteria and decreased Firmicutes. Curiously, Bacteroidetes were positively and Firmicutes were negatively correlated with serum ALT levels. Administration of FXR agonist CDCA inhibited NF-B activity and TNFα expression in vitro and improved liver IRI in vivo. Our findings demonstrate that FXR signaling plays an important role in the modulation of liver IRI.