Highlights d Fasting reduces the numbers of circulating monocytes in healthy humans and mice d Fasting also reduces monocyte metabolic and inflammatory activity d Hepatic energy-sensing regulates homeostatic monocyte numbers via CCL2 production d Fasting improves inflammatory diseases without compromising antimicrobial immunity

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide, and therapeutic options for advanced HCC are limited. Here, we observe that intestinal dysbiosis affects antitumor immune surveillance and drives liver disease progression towards cancer. Dysbiotic microbiota, as seen in Nlrp6−/− mice, induces a Toll-like receptor 4 dependent expansion of hepatic monocytic myeloid-derived suppressor cells (mMDSC) and suppression of T-cell abundance. This phenotype is transmissible via fecal microbiota transfer and reversible upon antibiotic treatment, pointing to the high plasticity of the tumor microenvironment. While loss of Akkermansia muciniphila correlates with mMDSC abundance, its reintroduction restores intestinal barrier function and strongly reduces liver inflammation and fibrosis. Cirrhosis patients display increased bacterial abundance in hepatic tissue, which induces pronounced transcriptional changes, including activation of fibro-inflammatory pathways as well as circuits mediating cancer immunosuppression. This study demonstrates that gut microbiota closely shapes the hepatic inflammatory microenvironment opening approaches for cancer prevention and therapy.

Proton pump inhibitor or long-term antibiotics intake, which have been linked to intestinal dysbiosis, are associated with increased risk of acute liver failure in the 500,000 participants of the UK BioBank population-based cohort. In mice, APAP intoxication prompts intestinal dysbiosis, barrier impairment, and bacterial translocation. Dysbiotic microbiota of Nlrp6-/mice induces a Ly6C hi phenotype of hepatic monocyte-derived macrophages and amplifies acute liver injury, a phenotype that is transferable to WT mice by fecal microbiota transfer. BACKGROUND & AIMS: Acute liver failure (ALF) represents an unmet medical need in Western countries. Although the link between intestinal dysbiosis and chronic liver disease is well-established, there is little evidence for a functional role of gut-liver interaction during ALF. Here we hypothesized that intestinal dysbiosis may affect ALF. METHODS: To test this hypothesis, we assessed the association of proton pump inhibitor (PPI) or long-term antibiotics (ABx) intake, which have both been linked to intestinal dysbiosis, and occurrence of ALF in the 500,000 participants of the UK Bio-Bank population-based cohort. For functional studies, male Nlrp6-/mice were used as a dysbiotic mouse model and injected with a sublethal dose of acetaminophen (APAP) or lipopolysaccharide (LPS) to induce ALF. RESULTS: Multivariate Cox regression analyses revealed a significantly increased risk (odds ratio, 2.3-3) for developing ALF in UK BioBank participants with PPI or ABx. Similarly, dysbiotic Nlrp6-/mice displayed exacerbated APAP-and LPS

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