The nonlinear association between triglyceride glucose-body mass index and femoral neck BMD in nondiabetic elderly men: NHANES 2005-March 2020.

BACKGROUND: The triglyceride glucose-body mass index (TyG-BMI) has been considered a surrogate marker for assessing insulin resistance. We aimed to correlate the TyG-BMI, triglyceride glucose combined with body mass index, with femoral neck bone mineral density (FN BMD) in non-diabetic elderly men. METHODS: Using data from the National Health and Nutrition Examination Survey (NHANES) database, totally, 1182 eligible men aged ≥ 50 years without diabetes were included in the current study. Smoothed curves were obtained by a two-piecewise linear regression model and the threshold effects were explored by using a smoothing function. RESULTS: TyG-BMI was positive related with and FN BMD with or without adjustment for confounders. However, no typical dose-dependent positive association between TyG-BMI and FN BMD was observed across the TyG-BMI tertiles, indicating a non-linear association. Further analysis by the weighted two-piecewise linear regression model and recursive algorithm suggested that per SD increase in TyG-BMI increased FN BMD by 0.266 gm/cm2 when TyG-BMI lower than 168.20. However, when TyG-BMI is higher than 168.20, FN BMD only increased 0.046 gm/cm2 for per SD increase of TyG-BMI after fully adjustment (OR = 11.258, 95%CI: 6.034, 16.481). Moreover, subgroup analyses showed that higher TyG-BMI levels were related to elevated FN BMD in all groups, suggesting the consistency of the positive association within these stratas. CONCLUSIONS: This study demonstrated that TyG-BMI is positively associated with FN BMD in a nonlinear fashion among elderly men without diabetes, which may be a reliable marker for the early identification of individuals with lower FN BMD.

U-shaped association between triglyceride and risk of incident diabetes in normoglycemic males with NAFLD: A population-base cohort study.

Background: Serum triglyceride (TG) was an important biomarker for nonalcoholic fatty liver disease (NAFLD), and the association between TG and incident type 2 diabetes mellitus is still under debate with some studies suggesting that elevated TG increase the risk of incident T2DM while others indicative of a negative relationship. These controversial findings may be partially due to the inclusion of the participants with NAFLD. The association between TG and incident type 2 diabetes mellitus in people with NAFLD remained unclear. Therefore, this study aimed to characterize the relationship between the baseline TG levels and incident type 2 diabetes mellitus in a male Japanese cohort with NAFLD. Methods: A total of 1221 males with NAFLD were enrolled from the Nagala (NAFLD in the Gifu Area Longitudinal analysis) study conducted from 2004 to 2015. Cox proportional hazards models were performed to examine the relationship between baseline TG concentration and incident type 2 diabetes mellitus. A two-piecewise linear regression model was explored to evaluate the threshold effect of the baseline TG levels on type 2 diabetes mellitus incidence by using a smoothing function. Results: During a median follow-up of 6.05 years, 39 males with NAFLD at baseline developed type 2 diabetes mellitus. The risk of incident type 2 diabetes mellitus was significantly associated with baseline TG concentration in males with NAFLD after fully adjustment for confounders, with per 10 mg/dl elevation in TG levels increasing the risk of incident diabetes by 8.5% (HR=1.085, CI=1.039-1.132; P<0.001). However, no typical dose-dependent positive association between type 2 diabetes mellitus incidence and the TG levels was observed across the TG tertiles. Interestingly, a U-shaped association between TG concentration and risk of incident type 2 diabetes mellitus was revealed by the two-piecewise linear regression analysis. Baseline TG concentration lower than the threshold values (TG <53mg/dl) were negatively associated with risk of incident type 2 diabetes mellitus. With each 10mg/dl increase in baseline TG levels, the risk of incident type 2 diabetes mellitus decreased by nearly 59% (HR=0.413, 95% CI=0.220-0.778). In contrast, when TG levels were higher than the threshold values (TG>53mg/dl), the risk of incident diabetes increased 9.1% with every 10mg TG elevation (HR=1.091, 95% CI=1.046-1.137). Conclusions: A U-shaped relationship was observed between baseline TG levels and incident type 2 diabetes mellitus in a male normoglycemic Japanese population with NAFLD, although extrapolation of the finding to other populations should be made with caution.

Association between triglyceride to high-density lipoprotein cholesterol ratio and type 2 diabetes risk in Japanese.

Abnormal lipid metabolism is known to increases the risk for metabolic diseases, such as type 2 diabetes mellitus(T2DM). The relationship between baseline ratio of triglyceride to HDL cholesterol (TG/HDL-C) and T2DM in Japanese adults was investigated in this study. Our secondary analysis included 8419 male and 7034 female Japanese subjects who were free of diabetes at baseline. The correlation between baseline TG/HDL-C and T2DM was analyzed by a proportional risk regression model, the nonlinear correlation between baseline TG/HDL-C and T2DM was analyzed by a generalized additive model (GAM), and the threshold effect analysis was performed by a segmented regression model. We conducted subgroup analyses in different populations. During the median 5.39 years follow-up, 373 participants, 286 males and 87 females, developed diabetes mellitus. After full adjustment for confounders, the baseline TG/HDL-C ratio positively correlated with the risk of diabetes (hazard ratio 1.19, 95% confidence interval 1.09-1.3), and smoothed curve fitting and two-stage linear regression analysis revealed a J-shaped relationship between baseline TG/HDL-C and T2DM. The inflection point for baseline TG/HDL-C was 0.35. baseline TG/HDL-C > 0.35 was positively associated with the development of T2DM (hazard ratio 1.2, 95% confidence interval 1.10-1.31). Subgroup analysis showed no significant differences in the effect between TG/HDL-C and T2DM in different populations. A J-shaped relationship was observed between baseline TG/HDL-C and T2DM risk in the Japanese population. When TG/HDL-C was higher than 0.35, there was a positive relationship between baseline TG/HDL-C and the incidence of diabetes mellitus.

LRP6 Bidirectionally Regulates Insulin Sensitivity through Insulin Receptor and S6K Signaling in Rats with CG-IUGR.

OBJECTIVE: Intrauterine growth restriction followed by postnatal catch-up growth (CG-IUGR) increases the risk of insulin resistance-related diseases. Low-density lipoprotein receptor-related protein 6 (LRP6) plays a substantial role in glucose metabolism. However, whether LRP6 is involved in the insulin resistance of CG-IUGR is unclear. This study aimed to explore the role of LRP6 in insulin signaling in response to CG-IUGR. METHODS: The CG-IUGR rat model was established via a maternal gestational nutritional restriction followed by postnatal litter size reduction. The mRNA and protein expression of the components in the insulin pathway, LRP6/ß-catenin and mammalian target of rapamycin (mTOR)/S6 kinase (S6K) signaling, was determined. Liver tissues were immunostained for the expression of LRP6 and ß-catenin. LRP6 was overexpressed or silenced in primary hepatocytes to explore its role in insulin signaling. RESULTS: Compared with the control rats, CG-IUGR rats showed higher homeostasis model assessment for insulin resistance (HOMA-IR) index and fasting insulin level, decreased insulin signaling, reduced mTOR/S6K/ insulin receptor substrate-1 (IRS-1) serine307 activity, and decreased LRP6/ß-catenin in the liver tissue. The knockdown of LRP6 in hepatocytes from appropriate-for-gestational-age (AGA) rats led to reductions in insulin receptor (IR) signaling and mTOR/S6K/IRS-1 serine307 activity. In contrast, LRP6 overexpression in hepatocytes of CG-IUGR rats resulted in elevated IR signaling and mTOR/S6K/IRS-1 serine307 activity. CONCLUSION: LRP6 regulated the insulin signaling in the CG-IUGR rats via two distinct pathways, IR and mTOR-S6K signaling. LRP6 may be a potential therapeutic target for insulin resistance in CG-IUGR individuals.

Nonlinear association between changes in fasting plasma glucose and the incidence of diabetes in a nondiabetic Chinese cohort.

BACKGROUND: Limited data show that changes in fasting plasma glucose (FPG changes) are related to the incidence of type 2 diabetes (T2D). We aimed to correlate FPG changes with incident diabetes and evaluate FPG changes as a marker to screen participants at high risk of T2D in China. METHODS: A total of 116,816 individuals were followed during a median follow-up of 3.10 years by secondary analysis in a nondiabetic Chinese cohort. The turning points were derived from a receiver operating characteristic curve. Hazard ratios (HRs) were evaluated by Cox proportional hazards models. RESULTS: A total of 2669 cases of T2D were identified (788 women and 1881 men). The age-standardized incidence of diabetes was 12.87 per 1000 person-years (women: 11.04; men: 14.69). A nonlinear relationship between FPG changes and incident diabetes is shown by the fitting curves. The curves were categorized into three stages by two turning points (-0.04 and 1.25 mmol/L) and conformed to the hook-like pattern: an initial decrease (stage-1), then a transient sharp elevation (stage-2), followed by a slow increase (stage-3). HRs per SD of FPG changes on incident diabetes varied with stage: stage-1: 0.16 (0.12, 0.23), stage-2: 0.20 (0.15, 0.28) and stage-3: 0.22 (0.16, 0.31). Compared with stage-1, the HR in stage-3 was significantly higher at 28.05 (23.99, 32.79), while the increase in stage-2 was slight at 2.16 (1.79, 2.61), and the HR in stage-3 rose to 30.09 (25.02, 36.19). CONCLUSIONS: FPG changes had a strong correlation with the incidence of T2D and was a steady indicator that was used to distinguish the participants at high risk of diabetes.

IUGR with catch-up growth programs impaired insulin sensitivity through LRP6/IRS-1 in male rats.

Intrauterine growth restriction combined with postnatal accelerated growth (CG-IUGR) could lead to long-term detrimental metabolic outcomes characterized by insulin resistance. As an indispensable co-receptor of Wnt signaling, LRP6 plays a critical role in the susceptibility of metabolic disorders. However, whether LRP6 is involved in the metabolic programing is still unknown. We hypothesized that CG-IUGR programed impaired insulin sensitivity through the impaired LRP6-mediated Wnt signaling in skeletal muscle. A CG-IUGR rat model was employed. The transcriptional and translational alterations of the components of the Wnt and the insulin signaling in the skeletal muscle of the male CG-IUGR rats were determined. The role of LRP6 on the insulin signaling was evaluated by shRNA knockdown or Wnt3a stimulation of LRP6. Compared with controls, the male CG-IUGR rats showed an insulin-resistant phenotype, with impaired insulin signaling and decreased expression of LRP6/ß-catenin in skeletal muscle. LRP6 knockdown led to reduced expression of the IR-ß/IRS-1 in C2C12 cell line, while Wnt3a-mediated LRP6 expression increased the expression of IRS-1 and IGF-1R but not IR-ß in the primary muscle cells of male CG-IUGR rats. The impaired LRP6/ß-catenin/IGF-1R/IRS-1 signaling is probably one of the critical mechanisms underlying the programed impaired insulin sensitivity in male CG-IUGR.

U-shaped association between the triglyceride-glucose index and the risk of incident diabetes in people with normal glycemic level: A population-base longitudinal cohort study.

BACKGROUND: Previous studies have shown that a high baseline triglyceride-glucose (TyG) index is a potential risk factor for type 2 diabetes mellitus (T2DM). However, for a low TyG index, findings have been inconsistent. Moreover, the association between the baseline TyG index and incident T2DM in individuals with normal glycemic levels remains unclear. Therefore, this longitudinal study further examined and characterized the association between the baseline TyG index and incident T2DM in Japanese adults with normal glycemic levels. . METHODS: The participants (7857 men and 6440 women) were selected from the NAGALA (NAfld in the Gifu Area Longitudinal Analysis) study that was conducted from 2004 to 2015. Cox proportional hazards models were used to evaluate the associations between baseline TyG index and T2DM incidence, and a two-piecewise linear regression model was used to examine the threshold effect of the baseline TyG index on incident T2DM using a smoothing function. RESULTS: During a median follow-up period of 5.26 (women) and 5.88 (men) years, 47 women and 182 men developed T2DM. The risk of T2DM was strongly associated with the baseline TyG index in the fully adjusted model in men but not in women, and no dose-dependent positive relationship between incident T2DM and the TyG index was observed across the TyG tertiles. Interestingly, the two-piecewise linear regression analysis revealed a U-shaped association between the baseline TyG index and incident T2DM. Baseline TyG index lower than the threshold values (TyG index < 7.27 in women and <7.97 in men) were negatively associated with incident T2DM (hazard ratio [HR] = 0.09, 95% confidence interval [CI] = 0.01-0.93, P = 0.0435 for women and HR = 0.21, 95% CI = 0.08-0.57, P = 0.0021 for men). In contrast, baseline TyG index higher than the threshold values (TyG index > 7.27 in women and >7.97 in men) were positively associated with incident T2DM (HR = 2.76, 95% CI = 1.20-6.34, P = 0.0166 for women and HR = 2.42, 95% CI = 1.66-3.53, P < 0.0001 for men). CONCLUSIONS: A U-shaped association was observed between the baseline TyG index and incident T2DM in a Japanese population.

Changes of LRP6/ß-catenin pathway in adipose tissue of rats with intrauterine growth restriction with catch-up growth.

To investigate the expression of low-density lipoprotein receptor-related protein 6 (LRP6)/ß-catenin pathway related proteins in adipose tissue of rats with intrauterine growth restriction with catch-up growth SD rats were randomly divided into nutrition-restriction rats and normal feed rats during pregnancy. CG-IUGR model was established by reducing the number of offspring in the nutrition-restriction rats (CG-IUGR group); while the rats in the control group were offspring of the normal feed pregnant rats. In order to exclude the interference of gender, male offspring mice were selected in both the CG-IUGR group and the control group in the following studies. The CG-IUGR group and the control group were subjected to glucose tolerance test at 12 weeks of age, and the perirenal adipose tissue samples were taken to observe the adipose structure by HE staining. Expression of LRP6, ß-catenin and insulin receptor substrate 1 (IRS-1) in adipocytes were examined by confocal microscopy. Protein expression of LRP6, ß-catenin and IRS-1 were measured by Western blotting. Blood glucose level and the area under the cure of CG-IUGR group were significantly higher than that of control group (both <0.05). Adipocyte size in the CG-IUGR group was significantly larger than that of control group, and the expression of LRP6, ß-catenin and IRS-1 protein in adipose tissue of the CG-IUGR group was significantly lower than that of control group (all <0.05). : The expression of LRP6/ß-catenin pathway related proteins is reduced in the adipose tissue in CG-IUGR rats, probably contributing to the insulin resistance in these rats.

ACE2 modulates glucose homeostasis through GABA signaling during metabolic stress.

The angiotensin-converting enzyme 2 (ACE2)/angiotensin 1-7 (A1-7)/MAS axis and glutamate decarboxylase 67 (GAD67)/gamma-aminobutyric acid (GABA) signal both exist in the islet and play important roles in regulating blood glucose metabolism. It has been reported that the activation of ACE2 in the brain increases GABA expression to improve biological effects; however, it is unclear whether there is functional correlation between the ACE2/A1-7/MAS axis and GAD67/GABA signal in the islet. In this study, we showed that the ACE2/A1-7/MAS and GABA signaling systems decreased in the islet of different metabolic stress models. In ACE2-knockout mice, we found that GAD67 and GABA expression decreased significantly, which was reversed by exogenous administration of A1-7. Furthermore, A1-7 mediated PDX1 and AKT activation was inhibited by allylglycine (a specific GAD67 inhibitor) in MIN6 cells. Moreover, giving A1-7 and GABA could significantly reduce beta-cell dedifferentiation and improved glucose metabolism during metabolic stress in vivo and in vitro. In conclusion, our study reveals that the ACE2/A1-7/MAS axis improves beta-cell function through regulating GAD67/GABA signal in beta cells and that up-regulating the ACE2/A1-7/MAS axis and GABA signals delays the development of obesity-induced diabetes.

Liraglutide Attenuates Non-Alcoholic Fatty Liver Disease in Mice by Regulating the Local Renin-Angiotensin System.

The renin-angiotensin system (RAS) is involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and represents a potential therapeutic target for NAFLD. Glucagon-like peptide-1 (GLP-1) signaling has been shown to regulate the RAS within various local tissues. In this study, we aimed to investigate the functional relationship between GLP-1 and the local RAS in the liver during NAFLD. Wild-type and ACE2 knockout mice were used to establish a high-fat-induced NAFLD model. After the mice were treated with liraglutide (a GLP-1 analogue) for 4 weeks, the key RAS component genes were up-regulated in the liver of NAFLD mice. Liraglutide treatment regulated the RAS balance, preventing a reduction in fatty acid oxidation gene expression and increasing gluconeogenesis and the expression of inflammation-related genes caused by NAFLD, which were impaired in ACE2 knockout mice. Liraglutide-treated HepG2 cells exhibited activation of the ACE2/Ang1-7/Mas axis, increased fatty acid oxidation gene expression, and decreased inflammation, which could be reversed by A779 and AngII. These results indicate that the local RAS in the liver becomes overactivated in response to NAFLD. Moreover, ACE2 knockout increases the severity of liver steatosis. Liraglutide has a negative and antagonistic effect on the ACE/AngII/AT1R axis, a positive impact on the ACE2/Ang1-7/Mas axis, and is mediated through the PI3K/AKT pathway. This may represent a potential new mechanism by which liraglutide improves NAFLD.

Activation of ACE2/angiotensin (1-7) attenuates pancreatic ß cell dedifferentiation in a high-fat-diet mouse model.

OBJECTIVE: Angiotensin-converting enzyme 2 (ACE2) has been identified in pancreatic islets and can preserve ß cells. In this study, we aimed to examine the possible role of ACE2 and its end product, angiotensin 1-7 (A1-7), in reducing ß cell dedifferentiation during metabolic stress. METHODS: First, a lineage-tracing experiment was performed to track ß cells in mice fed a high-fat diet (HFD). Second, the ACE2/A1-7 axis was evaluated in the HFD mouse model. Intraperitoneal glucose tolerance tests (IPGTTs) and intraperitoneal insulin tolerance tests (IPITTs) were conducted. Phenotypic changes in ß cells were detected by immunohistochemistry and quantitative real-time PCR. Pancreatic sections were immunostained for vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS). Finally, the effects of the ACE2/A1-7 axis were explored in isolated mouse islets exposed to different concentrations of glucose. Glucose-stimulated insulin release and levels of insulin mRNA and OCT4 mRNA were measured. RESULTS: Pancreatic ß cell dedifferentiation occurred both in vitro and in vivo in response to metabolic stress and was accompanied by ACE2 reduction. HFD-induced insulin resistance and glucose intolerance were exacerbated in ACE2-knockout (ACE2KO) mice but were alleviated by exogenous A1-7 in C57BL/6J mice. Approximately 20% of ß cells were dedifferentiated in ACE2KO mice fed a standard rodent chow diet (SD). A higher percentage of dedifferentiated ß cells was detected in ACE2KO mice than in wild-type (WT) mice under HFD conditions. In contrast, the administration of A1-7 alleviated HFD-induced ß cell dedifferentiation in C57BL/6J mice. Moreover, the exogenous injection of A1-7 improved microcirculation in islets and decreased the production of iNOS in islets of C57BL/6J mice fed an HFD. Additionally, ACE2 was found to be mainly expressed in α cells of mice, while Mas, the receptor of A1-7, was distributed in ß cells. CONCLUSIONS: Overall, this study is the first to demonstrate that the ACE2/A1-7/Mas axis may be one of the intra-islet paracrine mechanisms of communication between α and ß cells. Enhancing the ACE2/A1-7 axis exerts a protective effect by ameliorating ß cell dedifferentiation, and this effect might be partially mediated through improvements in islet microcirculation and suppression of islet iNOS.

Anti-profibrotic effects of artesunate on bleomycin-induced pulmonary fibrosis in Sprague Dawley rats.

The present study aimed to determine whether artesunate has beneficial effects on bleomycin-induced pulmonary fibrosis in rats and to examine the possible mechanisms underlying these effects. All experiments were performed with male Sprague Dawley rats weighing 180-250 g. Animals were randomly divided into four experimental groups that were administered either saline alone, artesunate alone, bleomycin alone or bleomycin + artesunate. Lung histopathology was investigated by hematoxylin and eosin staining and Masson staining. Lung profibrotic molecules were analyzed by reverse transcription polymerase chain reaction, immunoblotting and immunohistochemistry. In rats treated with artesunate, pulmonary fibrosis induced by bleomycin was significantly reduced. Administration of artesunate significantly improved bleomycin-induced morphological alterations. Profibrotic molecules, including transforming growth factor-ß1, Smad3, heat shock protein 47, α-smooth muscle actin and collagen type I were also reduced by artesunate. These findings suggest that artesunate improves bleomycin-induced pulmonary fibrosis pathology in rats possibly by inhibiting profibrotic molecules associated with pulmonary fibrosis.

[Relationship between artesunate influence on the process of TGF-beta1 induced alveolar epithelial cells transform into mesenchymal cells and on idiopathic pulmonary fibrosis].

This study is to investigate the effect of artesunate on transforming growth factor-beta1 (TGF-beta1) induced epithelial-mesenchymal transition (EMT) and its possible mechanism. After the in vitro cultured RLE-6TN cells were treated with TGF-beta1 then artesunate intervened on it, after 24 h, expression of the markers of mesenchymal cell was assayed using Western blotting and real-time PCR analysis. Western blotting was also used to detect the effect of TGF-beta1 on the Smad3 and Smad7 expressions of RLE-6TN cells. Morphological alterations were examined by phase-contrast microscope, and ultrastructure changes by electron microscope. Incubation of RLE-6TN cells with TGF-beta1 resulted in the up-regulation of the expression of the mesenchymal cell markers, after artesunate intervened on it, resulted in the down-regulation of the expression. Meanwhile, incubation with artesunate intervened on RLE-6TN cells could lead to the apparent down-regulation of the expression of Smad3 and up-regulation of Samd7 and the transition of RLE-6TN cells to mesenchymal-like by TGF-beta1 induction, after artesunate intervened on it, RLE-6TN cells to epithelial-like. TGF-beta1 induced epithelial-mesenchymal transition process; artesunate can inhibit TGF-beta1-induced epithelial-mesenchymal transition process, the possible mechanism is up-regulation of the expression of Smad7 and down-regulation of the expression of Smad3, meanwhile inhibits phosphorylation of Smad3.