Potential Effects of Regulating Intestinal Flora on Immunotherapy for Liver Cancer

The response of gut microbiota to arsenic metabolism is involved in arsenic-induced liver injury, which is influenced by the interaction between arsenic and methionine synthase

The drivers of changes in gut microbiota under arsenic exposure and the mechanism by which microbiota affect arsenic metabolism are still unclear. Here, C57BL/6 mice were exposed to 0, 5, or 10 ppm NaAsO2 in drinking water for 6 months. The results showed that arsenic exposure induced liver injury and increased the abundance of folic acid (FA)/vitamin B12 (VB12)- and butyrate-synthesizing microbiota. Statistical analysis and in vitro cultures showed that microbiota were altered to meet the demand for FA/VB12 by arsenic metabolism and to resist the toxicity of unmetabolized arsenic. However, at higher arsenic levels, changes of these microbiota were inconsistent. A 3D molecular simulation showed that arsenic bound to methionine synthase (MTR), which was confirmed by SEC-UV-DAD (1 μM recombinant human MTR was purified with 0 or 2 μM NaAsO2 at room temperature for 1 h) and fluorescence-labeled arsenic co-localization (primary hepatocytes were exposed to 0, 0.5, or 1 μM ReAsH-EDT2 for 24 h) in non-cellular and cellular systems. Mechanistically, the arsenic-MTR interaction in the liver interferes with the utilization of FA/VB12, which increases arsenic retention and thus results in a substantial increase in the abundance of butyrate-synthesizing microbiota compared to FA/VB12-synthesizing microbiota. By exposing C57BL/6J mice to 0 or 10 ppm NaAsO2 with or without FA (6 mg/L) and VB12 (50 μg/L) supplementation in their drinking water for 6 months, we constructed an FA/VB12 intervention mouse model and found that FA/VB12 supplementation blocked the disturbance of gut microbiota, restored MTR levels, promoted arsenic metabolism, and alleviated liver injury. We demonstrate that the change of gut microbiota is a response to arsenic metabolism, a process influenced by the arsenic-MTR interaction. This study provides new insights for understanding the relationship between gut microbiota and arsenic metabolism and present therapeutic targets for arseniasis.

Polysaccharides from Eucommia ulmoides Oliv. Leaves Alleviate Acute Alcoholic Liver Injury by Modulating the Microbiota-Gut-Liver Axis in Mice

The interplay among gut microbiota, intestines, and liver is crucial in preventing acute alcoholic liver injury. In this study, the hepatoprotective potential of polysaccharides from Eucommia ulmoides Oliv. leaves (EULP) on acute alcoholic liver injury in Kunming male mice was investigated. The structural features suggested that the EULP appeared as a heterogeneous mixture of polysaccharides with a molecular weight of 186132 Da. A 14-day pretreatment of EULP ameliorated acute alcoholic-induced hepatic inflam mation (TNF-α, IL-6, and IL-10), oxidative stress (GSH, SOD, and T-AOC), and liver damage (ALT and AST) via enhancing intestinal barrier (Occludin, Claudin 1, and ZO-1) and modulating microbiome, which subsequently inhibiting endotoxemia and balancing the homeostasis of the gut-liver axis. EULP restored the composition of intestinal flora with an increase in the relative abundance of Lactobacillaceae and a decrease in Lachnospiraceae and Verrucomicrobiaceae. Notably, prolonged EULP pretreatment (14 days) but no single gavage of EULP achieved excellent hepatoprotection. These findings endorsed the potential of EULP as a functional food for mitigating acute alcoholic-induce d liver damage, attributed to its anti-inflammatory, antioxidant, and prebiotic properties facilitated by the microbiota-gut-liver axis.

Mechanism-guided fine-tuned microbiome potentiates anti-tumor immunity in HCC

Microbiome, including bacteria, fungi, and viruses, plays a crucial role in shaping distal and proximal anti-tumor immunity. Mounting evidence showed that commensal microbiome critically modulates immunophenotyping of hepatocellular carcinoma (HCC), a leading cause of cancer-related death. However, their role in anti-tumor surveillance of HCC is still poorly understood. Herein, we spotlighted growing interests in how the microbiome influences the progression and immunotherapeutic responses of HCC via changing local tumor microenvironment (TME) upon translocating to the sites of HCC through different "cell-type niches". Moreover, we summarized not only the associations but also the deep insight into the mechanisms of how the extrinsic microbiomes interplay with hosts to shape immune surveillance and regulate TME and immunotherapeutic responses. Collectively, we provided a rationale for a mechanism-guided fine-tuned microbiome to be neoadjuvant immunotherapy in the near future.

Genetic predisposition of the gastrointestinal microbiome and primary biliary cholangitis: a bi-directional, two-sample Mendelian randomization analysis

Background

The gut-liver axis indicates a close relationship between the gastrointestinal microbiome (GM) and primary biliary cholangitis (PBC). However, the causality of this relationship remains unknown. This study investigates the causal relationship between the GM and PBC using a bidirectional, two-sample Mendelian randomization (MR) analysis.

Methods

Genome-wide association data for GM and PBC were obtained from public databases. The inverse-variance weighted method was the primary method used for MR analysis. Sensitivity analyses were conducted to assess the stability of the MR results. A reverse MR analysis was performed to investigate the possibility of reverse causality.

Results

Three bacterial taxa were found to be causally related to PBC. Class Coriobacteriia (odds ratio (OR) = 2.18, 95% confidence interval (CI): 1.295-3.661, P< 0.05) and order Coriobacteriales (OR = 2.18, 95% CI: 1.295-3.661, P<0.05) were associated with a higher risk of PBC. Class Deltaproteobacteria (OR = 0.52, 95% CI: 0.362-0.742, P< 0.05) had a protective effect on PBC. There was no evidence of reverse causality between PBC and the identified bacterial taxa.

Conclusion

Previously unrecognized taxa that may be involved in the pathogenesis of PBC were identified in this study, confirming the causality between the GM and PBC. These results provide novel microbial targets for the prevention and treatment of PBC.