Silencing of SAA1 inhibits palmitate- or high-fat diet induced insulin resistance through suppression of the NF-κB pathway.

BACKGROUND: Obesity is one of the leading causes of insulin resistance. Accumulating reports have highlighted that serum amyloid A-1 (SAA1) is a potential candidate that is capable of attenuating insulin resistance. Hence, we conducted the current study with aims of investigating our proposed hypothesis that silencing SAA1 could inhibit the progression of obesity-induced insulin resistance through the NF-κB pathway. METHODS: Gene expression microarray analysis was initially performed to screen differentially expressed genes (DEGs) associated with obesity. Palmitate (PA)-induced insulin resistance Huh7 cell models and high-fat diet (HFD)-induced mouse models were established to elucidate the effect of SAA1/Saa1 on insulin resistance. The NF-κB pathway-related expression was subsequently determined through the application of reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. RESULTS: Saa1 was identified as an obesity-related gene based on the microarray data of GSE39549. Saa1 was determined to be highly expressed in HFD-induced insulin resistance mouse models. PA-induced Huh7 cells, treated with silenced SAA1 or NF-κB pathway inhibition using BAY 11-7082, displayed a marked decrease in both Saa1 and SOCS3 as well as an elevation in 2DG, IRS1 and the extent of IRS1 phosphorylation. HFD mice treated with silenced Saa1 or inhibited NF-κB pathway exhibited improved fasting blood glucose (FBG) levels as well as fasting plasma insulin (FPI) levels, glucose tolerance and systemic insulin sensitivity. Saa1/SAA1 was determined to show a stimulatory effect on the transport of the NF-κBp65 protein from the cytoplasm to the nucleus both in vivo and in vitro, suggesting that Saa1/SAA1 could activate the NF-κB pathway. CONCLUSION: Taken together, our key findings highlight a novel mechanism by which silencing of SAA1 hinders PA or HFD-induced insulin resistance through inhibition of the NF-κB pathway.

Anxa2 gene silencing attenuates obesity-induced insulin resistance by suppressing the NF-κB signaling pathway.

Insulin resistance (IR) continues to pose a major threat to public health due to its role in the pathogenesis of metabolic syndrome and its ever-increasing prevalence on a global scale. The aim of the current study was to investigate the efficacy of Anxa2 in obesity-induced IR through the mediation of the NF-κB signaling pathway. Microarray analysis was performed to screen differentially expressed genes associated with obesity. To verify whether Anxa2 was differentially expressed in IR triggered by obesity, IR mouse models were established in connection with a high-fat diet (HFD). In the mouse IR model, the role of differentially expressed Anxa2 in glycometabolism and IR was subsequently detected. To investigate the effect of Anxa2 on IR and its correlation with inflammation, a palmitic acid (PA)-induced IR cell model was established, with the relationship between Anxa2 and the NF-κB signaling pathway investigated accordingly. Anxa2 was determined to be highly expressed in IR. Silencing Anxa2 was shown to inhibit IR triggered by obesity. When Anxa2 was knocked down, elevated expression of phosphorylated insulin receptor substrate 1 (IRS1), IRS1 and peroxisome proliferator-activated receptor coactivator-1a, and glucose tolerance and insulin sensitivity along with 2-deoxy-d-glucose uptake was detected, whereas decreased expression of suppressor of cytokine signaling 3, IL-6, IL-1ß, TNF-α, and p50 was observed. Taken together, the current study ultimately demonstrated that Anxa2 may be a novel drug strategy for IR disruption, indicating that Anxa2 gene silencing is capable of alleviating PA or HFD-induced IR and inflammation through its negative regulatory role in the process of p50 nuclear translocation of the NF-κB signaling pathway.

Expression of MicroRNA-448 and SIRT1 and Prognosis of Obese Type 2 Diabetic Mellitus Patients After Laparoscopic Bariatric Surgery.

BACKGROUND/AIMS: This study sought to investigate the expression and prognostic value of peripheral blood microRNA-448 (miR-448) and its target gene SIRT1 after laparoscopic bariatric surgery in obese type 2 diabetic mellitus (T2DM) patients. METHODS: Obese T2DM patients were selected and treated with laparoscopic bariatric surgery. Enzyme-linked immunosorbent assay (ELISA) was used to measure SIRT1 protein expression. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was employed to determine the mRNA expression of the related gene. Endothelial progenitor cells (EPCs) were grouped into blank, negative control (NC), miR-448 mimic, miR-448 inhibitor, siRNA-SIRT1 and miR-448 inhibitor + siRNA-SIRT1 groups. Transwell assays and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays were applied to determine cell invasion and cell viability. A tube formation assay and an adherence test were utilized to assess the angiogenic and adhesive capacities of the cells. RESULTS: In peripheral blood, the expression of miR-448 was reduced, whereas the mRNA and protein expression of SIRT1 was increased after surgery compared to before surgery. miR-448 expression was lower and mRNA and protein expression of SIRT1 was higher in the effective group than in the ineffective group after surgery. SIRT1 is a target gene of miR-448. miR-448 can suppress viability and invasion, and it reflects the angiogenic and adhesive capacity of EPCs and the protein expression of relative genes in EPCs through targeting SIRT1. CONCLUSION: The results demonstrated that miR-448 and its target gene SIRT1 can serve as prognostic indicators for obese T2DM patients after laparoscopic bariatric surgery.

Serum vaspin level as a predictive indicator in the amelioration of fatty liver and metabolic disturbance in patients with severe obesity after laparoscopic vertical banded gastroplasty.

BACKGROUND: This study is all about predicting the value of serum vaspin level in the amelioration of fatty liver and metabolic disturbance in patients with severe obesity after laparoscopic vertical banded gastroplasty (LVBG). METHODS: A total of 164 patients (from January 2012 to May 2015) with severe obesity were chosen and performed LVBG. Enzyme-linked immunosorbent assay was performed to detect the serum vaspin level. The patients were given a biochemical automatic analyzer to measure the biochemical indicators. Homeostasis model assessment (HOMA) helps in the calculation of fasting insulin level (FINS) and insulin resistance (IR). The changes in fatty liver were examined by computed tomography (CT). Receiver operating characteristic curve is used to increase the predictive value of serum vaspin level in the amelioration of liver function and disturbances in the metabolism. RESULTS: Weight, BMI, waist circumference, serum vaspin level, and triglyceride (TG) decreased, but CT value of liver increased at 4th, 7th, and 12th month after surgery. After the 7th and 12th month period of surgery, the alanine aminotransferase, aspartate aminotransferase, FINS, and HOMA-IR reduced in the patients (P <.005). The area under ROC curve (AUC) is about 0.871 ±â€Š0.031 with 95%CI of 0.810-0.931 (P <.001). The sensitivity, specificity, and accuracy of serum vaspin level ≤0.9 were 87.80%, 78.05%, and 83.28%, respectively. BMI, FINS, and serum vaspin level ≤0.9 were the influencing factors of the amelioration of fatty liver and metabolic disturbance. CONCLUSION: This study proves that the serum vaspin level serves as a predictive indicator in the amelioration of fatty liver and metabolic disturbance in patients with severe obesity after LVBG.