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Intestinal microbiome-macrophage crosstalk contributes to cholestatic liver disease by promoting intestinal permeability.

ABSTRACT: Mounting evidence supports an association between cholestatic liver disease and changes in the composition of the microbiome. Still, the role of the microbiome in the pathogenesis of this condition remains largely undefined. To address this, we have used two experimental models, administering ANIT or feeding a 0.1%DDC diet, to induce cholestatic liver disease in germ-free mice and germ-free mice conventionalized with the microbiome from WT SPF animals. Next, we have inhibited macrophage activation by depleting these cells using clodronate-liposomes and inhibiting the inflammasome with a specific inhibitor of Nlrp3. Our results demonstrate that cholestasis, the accumulation of bile acids in the liver, fails to promote liver injury in the absence of the microbiome in vivo. Additional in vitro studies supported that endotoxin sensitizes hepatocytes to bile acid-induced cell death. We also demonstrate that during cholestasis, macrophages contribute to promoting intestinal permeability and to altered microbiome composition via the activation of the inflammasome, overall leading to increased endotoxin flux into the cholestatic liver. In conclusion, we demonstrate that the intestinal microbiome contributes to cholestasis-mediated cell death and inflammation via mechanisms involving the activation of the inflammasome in macrophages.

SUBMITTER: Isaacs-Ten A

PROVIDER: S-EPMC7839474 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Intestinal Microbiome-Macrophage Crosstalk Contributes to Cholestatic Liver Disease by Promoting Intestinal Permeability in Mice.

Isaacs-Ten Anna A Echeandia Marta M Moreno-Gonzalez Mar M Brion Arlaine A Goldson Andrew A Philo Mark M Patterson Angela M AM Parker Aimee A Galduroz Mikel M Baker David D Rushbrook Simon M SM Hildebrand Falk F Beraza Naiara N

Hepatology (Baltimore, Md.) 20201201 6

<h4>Background and aims</h4>Mounting evidence supports an association between cholestatic liver disease and changes in the composition of the microbiome. Still, the role of the microbiome in the pathogenesis of this condition remains largely undefined.<h4>Approach and results</h4>To address this, we have used two experimental models, administering alpha-naphtylisocyanate or feeding a 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet, to induce cholestatic liver disease in germ-free mice and ge ...[more]

PMID: 32168395

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Project description:Impaired intestinal barrier function promotes the progression of various liver diseases, including cholestatic liver diseases. The close association of primary sclerosing cholangitis (PSC) with inflammatory bowel disease highlights the importance of the gut-liver axis. It has been reported that bile duct ligation (BDL)-induced liver fibrosis is significantly reduced in C/EBP homologous protein knockout (CHOP-/- ) mice. However, the underlying mechanisms remain unclear. In the current study, we demonstrate that BDL induces striking and acute hepatic endoplasmic reticulum (ER) stress responses after 1 day, which return to normal after 3 days. No significant hepatocyte apoptosis is detected 7-14 days following BDL. However, the inflammatory response is significantly increased after 7 days, which is similar to what we found in human PSC liver samples. BDL-induced loss of stemness in intestinal stem cells (ISCs), disruption of intestinal barrier function, bacterial translocation, activation of hepatic inflammation, M2 macrophage polarization and liver fibrosis are significantly reduced in CHOP-/- mice. In addition, intestinal organoids derived from CHOP-/- mice contain more and longer crypt structures than those from wild-type (WT) mice, which is consistent with the upregulation of stem cell markers (leucine-rich repeat-containing G-protein-coupled receptor 5, olfactomedin 4, and SRY [sex determining region Y]-box 9) and in vivo findings that CHOP-/- mice have longer villi and crypts as compared to WT mice. Similarly, mRNA levels of CD14, interleukin-1β, tumor necrosis factor-alpha, and monocyte chemotactic protein-1 are increased and stem cell proliferation is suppressed in the duodenum of patients with cirrhosis.ConclusionActivation of ER stress and subsequent loss of stemness of ISCs plays a critical role in BDL-induced systemic inflammation and cholestatic liver injury. Modulation of the ER stress response represents a potential therapeutic strategy for cholestatic liver diseases as well as other inflammatory diseases. (Hepatology 2018;67:1441-1457).

Project description:BackgroundThe hepatoprotective effect of interleukin 22 (IL-22) has been reported in several models of liver injuries, including alcohol-associated liver disease (ALD). However, the intestinal role of IL-22 in alcoholic hepatitis remains to be elucidated.MethodsIntestinal IL-22 levels were measured in mice fed with alcohol for 8 weeks. IL-22 was then administered to alcohol-fed mice to test its protective effects on alleviating alcoholic hepatitis, focusing on intestinal protection. Acute IL-22 treatment was conducted in mice to further explore the link between IL-22 and the induction of antimicrobial peptide (AMP). Intestinal epithelial cell-specific knockout of signal transducer and activator of transcription 3 (STAT3) mice were generated and used for organoid study to explore its role in IL-22-mediated AMP expression and gut barrier integrity.ResultsAfter alcohol feeding for 8 weeks, the intestinal levels of IL-22 were significantly reduced in mice. IL-22 treatment to alcohol-fed mice mitigated liver injury as indicated by normalized serum transaminase levels, improved liver histology, reduced lipid accumulation, and attenuated inflammation. In the intestine, alcohol-reduced Reg3γ and α-defensins levels were reversed by IL-22 treatment. IL-22 also improved gut barrier integrity and decreased endotoxemia in alcohol-fed mice. While alcohol feeding significantly reduced Akkermansia, IL-22 administration dramatically expanded this commensal bacterium in mice. Regardless of alcohol, acute IL-22 treatment induced a fast and robust induction of intestinal AMPs and STAT3 activation. By using in vitro cultured intestinal organoids isolated from WT mice and mice deficient in intestinal epithelial-STAT3, we further demonstrated that STAT3 is required for IL-22-mediated AMP expression. In addition, IL-22 also regulates intestinal epithelium differentiation as indicated by direct regulation of sodium-hydrogen exchanger 3 via STAT3.ConclusionOur study suggests that IL-22 not only targets the liver but also benefits the intestine in many aspects. The intestinal effects of IL-22 include regulating AMP expression, microbiota, and gut barrier function that is pivotal in ameliorating alcohol induced translocation of gut-derived bacterial pathogens and liver inflammation.

Project description:Placental growth factor (PlGF), a member of the vascular endothelial growth factor (VEGF) family, mediates wound healing and inflammatory responses, exerting an effect on liver fibrosis and angiogenesis; however, the precise mechanism remains unclear. The aims of this study are to identify the role of PlGF in liver inflammation and fibrosis induced by bile duct ligation (BDL) in mice and to reveal the underlying molecular mechanism. PlGF small interfering RNA (siRNA) or non-targeting control siRNA was injected by tail vein starting 2 days after BDL. Liver inflammation, fibrosis, angiogenesis, macrophage infiltration, and hepatic stellate cells (HSCs) activation were examined. Our results showed that PlGF was highly expressed in fibrotic livers and mainly distributed in activated HSCs and macrophages. Furthermore, PlGF silencing strongly reduced the severity of liver inflammation and fibrosis, and inhibited the activation of HSCs. Remarkably, PlGF silencing also attenuated BDL-induced hepatic angiogenesis, as evidenced by attenuated liver endothelial cell markers CD31 and von Willebrand factor immunostaining and genes or protein expression. Interestingly, these pathological ameliorations by PlGF silencing were due to a marked reduction in the numbers of intrahepatic F4/80+, CD68+, and Ly6C+ cell populations, which were reflected by a lower expression of these macrophage marker molecules in fibrotic livers. In addition, knockdown of PlGF by siRNA inhibited macrophages activation and substantially suppressed the expression of pro-inflammatory cytokines and chemokines in fibrotic livers. Mechanistically, evaluation of cultured RAW 264.7 cells revealed that VEGF receptor 1 (VEGFR1) mainly involved in mediating the role of PlGF in macrophages recruitment and activation, since using VEGFR1 neutralizing antibody blocking PlGF/VEGFR1 signaling axis significantly inhibited macrophages migration and inflammatory responses. Together, these findings indicate that PlGF plays an important role in liver inflammation, angiogenesis, and fibrosis by promoting hepatic macrophage recruitment and activation, and suggest that blockage of PlGF could be a promising novel therapy for chronic fibrotic liver diseases.

Dataset Information

Intestinal microbiome-macrophage crosstalk contributes to cholestatic liver disease by promoting intestinal permeability.

Publications

Intestinal Microbiome-Macrophage Crosstalk Contributes to Cholestatic Liver Disease by Promoting Intestinal Permeability in Mice.

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