Influence of Insulin Resistance and Adipocytokines on Elevated Serum Alanine Aminotransferase in Obese Patients

Analysis of the relationship between serum alanine aminotransferase and body composition in Chinese women

Objective

To investigate the relationships between serum alanine aminotransferase (ALT) and body composition among postmenopausal women in China.

Methods

A cross-sectional study was conducted with 776 postmenopausal women in China from May to July 2008. Clinical information was collected using a standardized questionnaire. Measures of body composition were obtained using dual X-ray absorptiometry. Body lean mass and fat mass indices were calculated by dividing total body lean/fat weight (kg) by body height squared (kg/m2). Blood samples were collected to assess liver and renal functions and lipid profiles. Analysis of variance, Pearson correlations, and multiple regression were used to analyze the associations between serum ALT and body composition.

Results

We found negative relationships of serum ALT with age, menopause duration, and serum HDL-C levels. Serum ALT was positively correlated with BMI, serum TG levels, and the lean mass index and fat mass index. In a multivariate model adjusted for age, menopause duration, serum TG, and HDL-C levels, a 1-unit increase in the fat mass index was associated with a 0.176 U/L increase in ALT (95% CI 0.020 to 0.050, P < 0.001).

Conclusion

Serum ALT was positively associated with the body fat mass index of postmenopausal women in China.

Citrulline counteracts overweight- and aging-related effects on adiponectin and leptin gene expression in rat white adipose tissue

We recently demonstrated that citrulline (CIT) reduced the expression of inflammatory genes in cultured explants from retroperitoneal (RET) white adipose tissue (WAT) from young (2–4 months) but not old (25 months) rats. Here we show that in RET WAT from old rats and high-fat-diet-fed (HFD) young rats, the basal expression of the leptin gene was increased (275–345%) whereas that of the adiponectin gene was decreased (48–60%), when compared to those from control-diet-fed (CD) young rats. We show also that in RET WAT from old rats, a diet supplemented with CIT for 3 months reduced macrophage (F4/80, CD68) and inflammation (interleukin-6, tumor necrosis factor-α) marker genes 23–97%. CIT supplementation lowered leptin mRNA 62% and increased adiponectin mRNA 232%. In cultured explants of RET WAT from 4 month-old CD, 4 month-old HFD and 25-month-old CD rats, the exposure to 2.5 mmol/L CIT for 24 h up-regulated adiponectin gene expression 151%, 362% and 216% respectively. In contrast, leptin gene expression was down-regulated 66% selectively in CIT-treated explants from 25-month-old CD rats. These results further support the proposed beneficial effect of CIT to counteract the deleterious effects of aging and overweight on the metabolic, inflammatory and endocrine functions of WAT.

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HFD and aging increase leptin mRNA and decrease adiponectin mRNA in rat adipose tissue.

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In old rats a CIT diet reduces leptin mRNA and augments adiponectin mRNA.

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In adipose tissue explants, CIT induces adiponectin mRNA whatever age and diet.

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CIT exposure of adipose tissue explants reduces leptin mRNA selectively in old rats.

Elevation of serum aminotransferase activity increases risk of carotid atherosclerosis in patients with non-alcoholic fatty liver disease

BACKGROUND AND AIM

Patients with non-alcoholic fatty liver disease (NAFLD) have an increased risk of atherosclerosis and alanine aminotransferase (ALT) is associated with insulin resistance independently of metabolic factors. The aim of the present study was to investigate whether NAFLD patients with ALT elevation had a higher risk of carotid atherosclerosis.

METHODS

A total of 190 individuals were enrolled from the health management center. Among them, 20 subjects were excluded due to the presence of hepatitis B surface antigen (HbsAg), anti-hepatitis C virus (HCV) and cardiovascular disease. NAFLD was diagnosed by ultrasound examination. Carotid ultrasonography was used to measure maximal intima-media thickness (IMT) of the common carotid artery (CCA) and IMT (mean) > 1.0 mm was defined as the presence of carotid atherosclerosis.

RESULTS

NAFLD patients with ALT elevation had increased risk of carotid atherosclerosis than those with normal ALT by Fisher's exact test (P < 0.05). Multivariate analyses showed that serum ALT levels were positively associated with carotid atherosclerosis after adjustment for age, sex, number of metabolic syndrome components or status of metabolic syndrome (OR, 1.44; 95% CI 1.09-1.89; OR, 1.45; 95% CI 1.11-1.91). In addition, the higher the serum ALT levels with every 10 IU/L increment, the greater the risk of carotid atherosclerosis.

CONCLUSIONS

Serum ALT levels are positively associated with the risk of carotid atherosclerosis in patients with NAFLD, suggesting that serum ALT levels could serve as a surrogate marker of cardiovascular risk in this special clinical setting.