Mendelian randomisation analysis of clustered causal effects of body mass on cardiometabolic biomarkers

Chinese medicine Jiangzhuo mixture regulates glucose and lipid metabolism in obese rats through TLR4/IB/NF-B signaling pathway

OBJECTIVES

To explore the mechanism of Chinese medicine Jiangzhuo mixture regulating glucose and lipid metabolism in obese rats.

METHODS

Thirty healthy male SD rats were randomly divided into normal control group, model control group, and Jiangzhuo mixture treatment group, with 10 rats in each group. The rats in the normal control group were fed with normal diet, the obesity model was induced by feeding high-fat diet in the model control group and the Jiangzhuo mixture treatment group, the rats in the treatment group were given with Jiangzhuo mixture 50 g/kg by gavage. After 8 weeks of intervention, the blood glucose (GLU), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels were measured in the three groups. Quantitative reverse transcription PCR were used to detect the expression levels of PR domain containing 16 (PRDM16) and uncoupling protein 1 (UCP1) in white and brown adipose tissues of the rats in each group; Western blotting was used to detect the expression of PRDM16 in the white and brown adipose tissue of rats, and Toll-like receptor 4 (TLR4), nuclear factor-κB (NF-κB) and inhibitor of NF-κB alpha (IκBα) in the white adipose tissue; immunohistochemistry was used to detect the expression of UCP1 protein in white and brown adipose tissues.

RESULTS

Compared with the normal control group, the white fat weight (P<0.01), white fat coefficient (P<0.05) and Lee's coefficient (P<0.01) were significantly increased in the model control group; the contents of GLU, TC, TG and LDL-C were all increased, and the content of TG was significantly increased (P<0.05) in the model control group. The mRNA and protein expression levels of PRDM16 and UCP1 in white fat and brown fat were significantly decreased (P<0.05) in the model control group. Compared with the model control group, the white fat weight and white fat coefficient and Lee's coefficient were significantly reduced in the Jiangzhuo mixture treatment group (all P<0.01), the levels of GLU, TC, TG, and LDL-C in the the treatment group were all reduced, and the content of TG was reduced more obviously (P<0.01); expression levels of PRDM16 and UCP1 mRNA and protein were increased in brown and white adipose tissue. Compared with the normal control group, the expression levels of TLR4, phospho-IκBα and NF-κB-p65 proteins in white adipose tissue of the model control group were significantly increased (all P<0.01), while the expression levels of these proteins in the treatment group were significantly lower than those in the model control group (all P<0.05).

CONCLUSIONS

Jiangzhuo mixture can alleviate high-fat diet-induced increase in body fat, abnormal expression of biochemical indexes and promote the expression of key proteins including UCP1 and PRDM16 in white and brown adipose tissues by regulating TLR4/IκBα/NF-κB signaling pathway.

Effect of General Adiposity and Central Body Fat Distribution on the Circulating Metabolome: A Multicohort Nontargeted Metabolomics Observational and Mendelian Randomization Study

Obesity is associated with adverse health outcomes, but the metabolic effects have not yet been fully elucidated. We aimed to investigate the association between adiposity and circulating metabolites and to address causality with Mendelian randomization (MR). Metabolomics data were generated with nontargeted ultraperformance liquid chromatography coupled to time-of-flight mass spectrometry in plasma and serum from three population-based Swedish cohorts: ULSAM (N = 1,135), PIVUS (N = 970), and TwinGene (N = 2,059). We assessed associations of general adiposity measured as BMI and central body fat distribution measured as waist-to-hip ratio adjusted for BMI (WHRadjBMI) with 210 annotated metabolites. We used MR analysis to assess causal effects. Lastly, we attempted to replicate the MR findings in the KORA and TwinsUK cohorts (N = 7,373), the CHARGE Consortium (N = 8,631), the Framingham Heart Study (N = 2,076), and the DIRECT Consortium (N = 3,029). BMI was associated with 77 metabolites, while WHRadjBMI was associated with 11 and 3 metabolites in women and men, respectively. The MR analyses in the Swedish cohorts suggested a causal association (P value <0.05) of increased general adiposity and reduced levels of arachidonic acid, dodecanedioic acid, and lysophosphatidylcholine (P-16:0) as well as with increased creatine levels. The results of the replication effort provided support for a causal association of adiposity with reduced levels of arachidonic acid (P value = 0.03). Adiposity is associated with variation of large parts of the circulating metabolome; however, further investigation of causality is required in well-powered cohorts.