Mechanism of Metabolic Response to Hepatectomy by Integrated Analysis of Gut Microbiota, Metabolomics, and Proteomics

The integrated analysis of gut microbiota and metabolome revealed steroid hormone biosynthesis is a critical pathway in liver regeneration after 2/3 partial hepatectomy

Introduction: The liver is the only organ capable of full regeneration in mammals. However, the exact mechanism of gut microbiota and metabolites derived from them relating to liver regeneration has not been fully elucidated. Methods: To demonstrate how the gut-liver axis contributes to liver regeneration, using an LC-QTOF/MS-based metabolomics technique, we examine the gut microbiota-derived metabolites in the gut content of C57BL/6J mice at various points after 2/3 partial hepatectomy (PHx). Compound identification, multivariate/univariate data analysis and pathway analysis were performed subsequently. The diversity of the bacterial communities in the gastrointestinal content was measured using 16S rRNA gene sequencing. Then, the integration analysis of gut microbiota and metabolome was performed. Results: After 2/3 PHx, the residual liver proliferated quickly in the first 3 days and had about 90% of its initial weight by the seventh day. The results of PLS-DA showed that a significant metabolic shift occurred at 6 h and 36 h after 2/3 PHx that was reversed at the late phase of liver regeneration. The α and β-diversity of the gut microbiota significantly changed at the early stage of liver regeneration. Specifically, Escherichia Shigella, Lactobacillus, Akkermansia, and Muribaculaceae were the bacteria that changed the most considerably during liver regeneration. Further pathway analysis found the most influenced co-metabolized pathways between the host and gut bacteria including glycolysis, the TCA cycle, arginine metabolism, glutathione metabolism, tryptophan metabolism, and purine and pyrimidine metabolism. Specifically, steroid hormone biosynthesis is the most significant pathway of the host during liver regeneration. Discussion: These findings revealed that during liver regeneration, there was a broad modification of gut microbiota and systemic metabolism and they were strongly correlated. Targeting specific gut bacterial strains, especially increasing the abundance of Akkermansia and decreasing the abundance of Enterobacteriaceae, may be a promising beneficial strategy to modulate systemic metabolism such as amino acid and nucleotide metabolism and promote liver regeneration.

From Hypothalamic Obesity to Metabolic Dysfunction-Associated Steatotic Liver Disease: Physiology Meets the Clinics via Metabolomics

Metabolic health is tightly regulated by neuro-hormonal control, and systemic metabolic dysfunction may arise from altered function of the hypothalamic-anterior pituitary axis (HAPA). Ancient experimental observations of hypothalamic obesity (HO) and liver cirrhosis occurring among animals subjected to hypothalamic injury can now be explained using the more recent concepts of lipotoxicity and metabolic dysfunction-associated steatotic liver disease (MASLD). Lipotoxicity, the range of abnormalities resulting from the harmful effects of fatty acids accumulated in organs outside of adipose tissue, is the common pathogenic factor underlying closely related conditions like hypothalamic syndrome, HO, and MASLD. The hormonal deficits and the array of metabolic and metabolomic disturbances that occur in cases of HO are discussed, along with the cellular and molecular mechanisms that lead, within the MASLD spectrum, from uncomplicated steatotic liver disease to steatohepatitis and cirrhosis. Emphasis is placed on knowledge gaps and how they can be addressed through novel studies. Future investigations should adopt precision medicine approaches by precisely defining the hormonal imbalances and metabolic dysfunctions involved in each individual patient with HO, thus paving the way for tailored management of MASLD that develops in the context of altered HAPA.

d-Pinitol Improves Diabetic Sarcopenia by Regulation of the Gut Microbiome, Metabolome, and Proteome in STZ-Induced SAMP8 Mice

d-Pinitol (DP) is primarily found in Vigna sinensis, which has been shown to have hypoglycemic and protective effects on target organs. However, the mechanism of DP in treating diabetic sarcopenia (DS) is still unclear. To explore the underlying mechanism of DS and the protective targets of DP by high-throughput analysis of 16S rRNA gene, metabolome, and the proteome. Streptozotocin-induced SAMP8 mice were intragastrically administrated DP (150 mg/kg) for 8 weeks. Fecal 16S rRNA gene sequencing and gastrocnemius muscle metabolomic and proteomic analyses were completed to investigate the gut-muscle axis interactions. DP significantly alleviated the muscle atrophy in diabetic mice. Dysfunction of the gut microbiota was observed in the DS mice. DP significantly reduced the Parabacteroides, Akkermansia, and Enterobacteriaceae, while it increased Lachnospiraceae_NK4A136. Metabolome and proteome revealed that 261 metabolites and 626 proteins were significantly changed in the gastrocnemius muscle of diabetic mice. Among these, DP treatment restored 44 metabolites and 17 proteins to normal levels. Functional signaling pathways of DP-treated diabetic mice included nucleotide metabolism, β-alanine, histidine metabolism, ABC transporters, and the calcium signaling pathway. We systematically explored the molecular mechanism of DS and the protective effect of DP, providing new insights that may advance the treatment of sarcopenia.

Molecular mechanism and therapeutic significance of essential amino acids in metabolically associated fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), also known as metabolically associated fatty liver disease (MAFLD), is a systemic metabolic disease characterized by lipid accumulation in the liver, lipid toxicity, insulin resistance, intestinal dysbiosis, and inflammation that can progress from simple steatosis to nonalcoholic steatohepatitis (NASH) and even cirrhosis or cancer. It is the most prevalent illness threatening world health. Currently, there are almost no approved drug interventions for MAFLD, mainly dietary changes and exercise to control weight and regulate metabolic disorders. Meanwhile, the metabolic pathway involved in amino acid metabolism also influences the onset and development of MAFLD in the body, and most amino acid metabolism takes place in the liver. Essential amino acids are those amino acids that must be supplemented from outside the diet and that cannot be synthesized in the body or cannot be synthesized at a rate sufficient to meet the body's needs, including leucine, isoleucine, valine (collectively known as branched-chain amino acids), tryptophan, phenylalanine (which are aromatic amino acids), histidine, methionine, threonine and lysine. The metabolic balance of the body is closely linked to these essential amino acids, and essential amino acids are closely linked to the pathophysiological process of MAFLD. In this paper, we will focus on the metabolism of essential amino acids in the body and further explore the therapeutic strategies for MAFLD based on the studies conducted in recent years.