The bile acid induced hepatokine orosomucoid suppresses adipocyte differentiation

The Hepatokine Orosomucoid 2 Mediates Beneficial Metabolic Effects of Bile Acids

Bile acids (BAs) are pleiotropic regulators of metabolism. Elevated levels of hepatic and circulating BAs improve energy metabolism in peripheral organs, but the precise mechanisms underlying the metabolic benefits and harm still need to be fully understood. In the current study, we identified orosomucoid 2 (ORM2) as a liver-secreted hormone (i.e., hepatokine) induced by BAs and investigated its role in BA-induced metabolic improvements in mouse models of diet-induced obesity. Contrary to our expectation, under a high-fat diet (HFD), our Orm2 knockout (Orm2-KO) exhibited a lean phenotype compared with C57BL/6J control, partly due to the increased energy expenditure. However, when challenged with a HFD supplemented with cholic acid, Orm2-KO eliminated the antiobesity effect of BAs, indicating that ORM2 governs BA-induced metabolic improvements. Moreover, hepatic ORM2 overexpression partially replicated BA effects by enhancing insulin sensitivity. Mechanistically, ORM2 suppressed interferon-γ/STAT1 activities in inguinal white adipose tissue depots, forming the basis for anti-inflammatory effects of BAs and improving glucose homeostasis. In conclusion, our study provides new insights into the molecular mechanisms of BA-induced liver-adipose cross talk through ORM2 induction.

ARTICLE HIGHLIGHTS

Microbiological and metabolic pathways analysing the mechanisms of alfalfa polysaccharide and sulfated alfalfa polysaccharide in alleviating obesity

Alfalfa polysaccharide (AP) and sulfated alfalfa polysaccharide (SAP) exhibit potential for alleviating obesity. This study aimed to analyze the mechanism of action of AP and SAP in alleviating obesity through combined microbiomics and metabolomics. The research selected validated optimal AP and SAP concentration for experiment. The results showed that AP and SAP down-regulated colonic inflammatory gene expression, regulated intestinal pH to normal, and restored intestinal growth. Microbial sequencing showed that AP and SAP altered the microbial composition ratio. AP increased the relative abundance of Muribaculaceae and Romboutsia. SAP increased the relative abundance of Dubosiella, Fecalibaculum and Desulfovibrionaceae. Metabolomic analysis showed that AP regulated steroid hormone biosynthesis, neuroactive ligand-receptor interactions and bile secretion pathways. SAP focuses more on pathways related to amino acid metabolism. Meanwhile, AP and SAP down-regulated the mRNA expression of colonic COX-2, PepT-1 and HK2 and up-regulated the mRNA expression of TPH1. Correlation analysis showed a strong correlation between metabolites and gut bacteria. Dubosiella, Faecalibaculum may be the critical marker flora for polysaccharides to alleviate obesity. This study indicates that AP and SAP alleviate obesity through different pathways and that specific polysaccharide modifications affect characteristic microbial and metabolic pathways, providing new insights into polysaccharide modifications.

Serum Orosomucoid Is Associated with Serum Adiponectin, Adipose Tissue Insulin Resistance Index, and a Family History of Type 2 Diabetes in Young Normal Weight Japanese Women

INTRODUCTION

Adipose tissue (AT) expandability may be facilitated by adiponectin and suppressed by orosomucoid, and reduced AT expandability may be associated with first-degree relatives of type 2 diabetes. We tested the hypothesis that orosomucoid may be associated not only with adiponectin and adipose tissue insulin resistance but also with a family history of type 2 diabetes (FHD). Research Design and Methods. Anthropometric and metabolic variables, adipokines, and measures of inflammatory and insulin resistance were cross-sectionally investigated in 153 young normal weight Japanese women. Stepwise multivariate linear regression analyses were used to identify the most important determinants of orosomucoid.

RESULTS

Orosomucoid was higher in women with positive (n = 57) compared to women with negative FHD and was associated positively with FHD (both p = 0.01). Orosomucoid also showed positive associations with fasting glucose (p < 0.001), free fatty acids (p = 0.001), and HbA1c (p = 0.007), whereas there was no association with fasting insulin and serum lipids. In addition, orosomucoid was associated inversely with adiponectin (p = 0.02) and positively with adipose tissue-insulin resistance index (AT-IR, the product of fasting insulin and free fatty acids; p = 0.001) but not with homeostasis model assessment-insulin resistance, leptin, and high-sensitivity C-reactive protein. In multivariate analyses, AT-IR (standardized β, 0.22; p = 0.003), serum adiponectin (standardized β, -0.163; p = 0.032), FHD+ (standardized β, 0.178; p = 0.029), and HbA1c (standardized β, 0.213; p = 0.005) emerged as independent determinants of orosomucoid and explained 15.2% of its variability.

CONCLUSIONS

These results are the first to demonstrate that orosomucoid is associated not only with adipose tissue-insulin resistance and adiponectin but also with FHD.

Into the Labyrinth of the Lipocalin α1-Acid Glycoprotein

α₁-acid glycoprotein (AGP), also known as Orosomucoid (ORM), belongs to the Lipocalin protein family and it is well-known for being a positive acute-phase protein. AGP is mostly found in plasma, with the liver as main contributor, but it is also expressed in other tissues such as the brain or the adipose tissue. Despite the vast literature on AGP, the physiological functions of the protein remain to be elucidated. A large number of activities mostly related to protection and immune system modulation have been described. Recently created AGP-knockout models have suggested novel physiological roles of AGP, including regulation of metabolism. AGP has an outstanding ability to efficiently bind endogenous and exogenous small molecules that together with the complex and variable glycosylation patterns, determine AGP functions. This review summarizes and discusses the recent findings on AGP structure (including glycans), ligand-binding ability, regulation, and physiological functions of AGP. Moreover, this review explores possible molecular and functional connections between AGP and other members of the Lipocalin protein family.

Total flavonoids of Astragalus Ameliorated Bile Acid Metabolism Dysfunction in Diabetes Mellitus

Astragalus Radix is one of the common traditional Chinese medicines used to treat diabetes. However, the underlying mechanism is not fully understood. Flavones are a class of active components that have been reported to exert various activities. Existing evidence suggests that flavones from Astragalus Radix may be pivotal in modulating progression of diabetes. In this study, total flavones from Astragalus Radix (TFA) were studied to observe its effects on metabolism of bile acids both in vivo and in vitro. C57BL/6J mice were treated with STZ and high-fat feeding to construct diabetic model, and HepG2 cell line was applied to investigate the influence of TFA on liver cells. We found a serious disturbance of bile acids and lipid metabolism in diabetic mice, and oral administration or cell incubation with TFA significantly reduced the production of total cholesterol (TCHO), total triglyceride, glutamic oxalacetic transaminase (AST), glutamic-pyruvic transaminase (ALT), and low-density lipoprotein (LDL-C), while it increased the level of high-density lipoprotein (HDL-C). The expression of glucose transporter 2 (GLUT2) and cholesterol 7α-hydroxylase (CYP7A1) was significantly upregulated on TFA treatment, and FXR and TGR5 play pivotal role in modulating bile acid and lipid metabolism. This study supplied a novel understanding towards the mechanism of Astragalus Radix on controlling diabetes.