In type 2 diabetes induced by cigarette smoking, activation of p38 MAPK is involved in pancreatic β-cell apoptosis

Integrated metabolomic and transcriptomic analysis reveals the effects and mechanisms of Jinqi Jiangtang tablets on type 2 diabetes

BACKGROUND

Type 2 diabetes (T2DM) is one of the major metabolic diseases and poses a serious challenge to human life and global economic development. Jinqi Jiangtang Tablets (JQJT) is effective in ameliorating the effects of T2DM, but the mechanism of JQJT is unclear.

PURPOSE

This study integrated metabolomics and transcriptomics to reveal the mechanism by which JQJT improves T2DM.

METHODS

The T2DM mouse model was established, and the effects of JQJT on improving T2DM were evaluated by determining the levels of blood lipids, fasting blood glucose (FBG), insulin metabolism and hepatic lipid accumulation in mice after JQJT administration for 8 weeks. Serum metabolites were detected using ultra-performance liquid chromatography/quadrupole time-of-flight-tandem mass spectrometry (UPLC-Q-TOF-MS) technology, and mouse liver differential genes were detected using transcriptomic technology. Correlation analysis was used to extract metabolites and RNA with correlations, and potential pathways were enriched and constructed using the common pathway analysis function of MetaboAnalyst 5.0. Finally, the expression of key target proteins and genes was verified by Western blot (WB) and Polymerase Chain Reaction (PCR) to further elucidate the mechanism by which JQJT improves T2DM.

RESULTS

JQJT reduced FBG and lipid levels, improved insulin resistance (IR) and hepatic lipoatrophy in mice. A total of 35 differentially abundant metabolites were identified by metabolomics, and 328 differential genes were detected by transcriptomics. The integrated metabolomics and transcriptomics results suggested that JQJT may ameliorate T2DM mainly by regulating glucose and lipid metabolic pathways. WB and PCR results showed that JQJT regulates the insulin signaling pathway, involved in fatty acid metabolism, glycogen synthesis and catabolism.

CONCLUSIONS

JQJT improved IR in T2DM mice by regulating the insulin signaling pathway, improving glycogen synthesis and glycolysis, and increasing hepatic triglyceride and fatty acid metabolism.

miR-153-3p via PIK3R1 Is Involved in Cigarette Smoke-Induced Neurotoxicity in the Brain

Cigarettes contain various chemicals that cause damage to nerve cells. Exposure to cigarette smoke (CS) causes insulin resistance (IR) in nerve cells. However, the mechanisms for a disorder in the cigarette-induced insulin signaling pathway and in neurotoxicity remain unclear. Therefore, we evaluated, by a series of pathology analyses and behavioral tests, the neurotoxic effects of chronic exposure to CS on C57BL/6 mice. Mice exposed to CS with more than 200 mg/m3 total particulate matter (TPM) exhibited memory deficits and cognitive impairment. Pathological staining of paraffin sections of mouse brain tissue revealed that CS-exposed mice had, in the brain, neuronal damage characterized by thinner pyramidal and granular cell layers and fewer neurons. Further, the exposure of SH-SY5Y cells to cigarette smoke extract (CSE) resulted in diminished insulin sensitivity and reduced glucose uptake in a dose-dependent fashion. The PI3K/GSK3 insulin signaling pathway is particularly relevant to neurotoxicity. microRNAs are involved in the PI3K/GSK3β/p-Tau pathway, and we found that cigarette exposure activates miR-153-3p, decreases PI3K regulatory subunits PIK3R1, and induces Tau hyperphosphorylation. Exposure to an miR-153 inhibitor or to a PI3K inhibitor alleviated the reduced insulin sensitivity caused by CS. Therefore, our results indicate that miR-153-3p, via PIK3R1, causes insulin resistance in the brain, and is involved in CS-induced neurotoxicity.

Xenobiotics Delivered by Electronic Nicotine Delivery Systems: Potential Cellular and Molecular Mechanisms on the Pathogenesis of Chronic Kidney Disease

Chronic kidney disease (CKD) is characterized as sustained damage to the renal parenchyma, leading to impaired renal functions and gradually progressing to end-stage renal disease (ESRD). Diabetes mellitus (DM) and arterial hypertension (AH) are underlying diseases of CKD. Genetic background, lifestyle, and xenobiotic exposures can favor CKD onset and trigger its underlying diseases. Cigarette smoking (CS) is a known modified risk factor for CKD. Compounds from tobacco combustion act through multi-mediated mechanisms that impair renal function. Electronic nicotine delivery systems (ENDS) consumption, such as e-cigarettes and heated tobacco devices, is growing worldwide. ENDS release mainly nicotine, humectants, and flavorings, which generate several byproducts when heated, including volatile organic compounds and ultrafine particles. The toxicity assessment of these products is emerging in human and experimental studies, but data are yet incipient to achieve truthful conclusions about their safety. To build up the knowledge about the effect of currently employed ENDS on the pathogenesis of CKD, cellular and molecular mechanisms of ENDS xenobiotic on DM, AH, and kidney functions were reviewed. Unraveling the toxic mechanisms of action and endpoints of ENDS exposures will contribute to the risk assessment and implementation of proper health and regulatory interventions.

Statistical Bioinformatics to Uncover the Underlying Biological Mechanisms That Linked Smoking with Type 2 Diabetes Patients Using Transcritpomic and GWAS Analysis

Type 2 diabetes (T2D) is a chronic metabolic disease defined by insulin insensitivity corresponding to impaired insulin sensitivity, decreased insulin production, and eventually failure of beta cells in the pancreas. There is a 30–40 percent higher risk of developing T2D in active smokers. Moreover, T2D patients with active smoking may gradually develop many complications. However, there is still no significant research conducted to solve the issue. Hence, we have proposed a highthroughput network-based quantitative pipeline employing statistical methods. Transcriptomic and GWAS data were analysed and obtained from type 2 diabetes patients and active smokers. Differentially Expressed Genes (DEGs) resulted by comparing T2D patients’ and smokers’ tissue samples to those of healthy controls of gene expression transcriptomic datasets. We have found 55 dysregulated genes shared in people with type 2 diabetes and those who smoked, 27 of which were upregulated and 28 of which were downregulated. These identified DEGs were functionally annotated to reveal the involvement of cell-associated molecular pathways and GO terms. Moreover, protein–protein interaction analysis was conducted to discover hub proteins in the pathways. We have also identified transcriptional and post-transcriptional regulators associated with T2D and smoking. Moreover, we have analysed GWAS data and found 57 common biomarker genes between T2D and smokers. Then, Transcriptomic and GWAS analyses are compared for more robust outcomes and identified 1 significant common gene, 19 shared significant pathways and 12 shared significant GOs. Finally, we have discovered protein–drug interactions for our identified biomarkers.

lncRNA TUG1 protects intestinal epithelial cells from damage induced by high glucose and high fat via AMPK/SIRT1

he incidence of obesity and type 2 diabetes mellitus (T2DM) is increasing year by year and shows a trend towards younger age groups worldwide. It has become a disease that endangers the health of individuals all over the world. Among numerous weight loss surgeries, sleeve gastrectomy (SG) has become one of the most common surgical strategies for the treatment of T2DM. However, SG‑mediated alterations to the molecular mechanism of metabolism require further investigation. Thus, reverse transcription‑quantitative PCR was used to detect the expression levels of long non‑coding (lnc)RNA taurine‑upregulated gene 1 (TUG1), Sirtuin 1 (SIRT1), AMP‑activated protein kinase (AMPK) and uncoupling protein 2 (UCP2) in the serum of T2DM patients, as well as in HIEC‑6 and SW480 cells following treatment with high glucose and high fat (HGHF). Protein expression was detected by western blotting. Cell Counting Kit‑8 assays were performed to analyze cell viability, and flow cytometry and a TUNEL assay was performed to evaluate cell apoptosis. The secretion of ILs in the culture medium was detected by conducting ELISAs. The results showed that lncRNA TUG1 and UCP2 expression was upregulated, SIRT1 and AMPK expression levels were decreased by SG. Under HGHF conditions, HIEC‑6 and SW480 cell viability was inhibited, apoptosis was promoted, TUG1 expression was downregulated, and SIRT1 and AMPK expression levels were upregulated. The secretory levels of IL‑1β, IL‑6 and IL‑8 were increased, whereas the secretion of IL‑10 was decreased under HGHF conditions. lncRNA TUG1 overexpression significantly reversed the effects of HGHF on cell viability, apoptosis and SIRT1, AMPK, UCP2 and Bcl‑2 expression levels. Together, the findings of the present study demonstrated that lncRNA TUG1 alleviated the damage induced by HGHF in intestinal epithelial cells by downregulating SIRT1 and AMPK expression, and upregulating UCP2 expression. Thus, the lncRNA TUG1/AMPK/SIRT1/UCP2 axis may serve an important role in the treatment of T2DM.

Causal effect of education on type 2 diabetes: A network Mendelian randomization study

BACKGROUND

The causality between education and type 2 diabetes (T2DM) remains unclear.

AIM

To identify the causality between education and T2DM and the potential metabolic risk factors [coronary heart disease (CHD), total cholesterol, low-density lipoprotein, triglycerides (TG), body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), fasting insulin, fasting glucose, and glycated hemoglobin] from summarized genome-wide association study (GWAS) data used a network Mendelian randomization (MR).

METHODS

Two-sample MR and network MR were performed to obtain the causality between education-T2DM, education-mediator, and mediator-T2DM. Summary statistics from the Social Science Genetic Association Consortium (discovery data) and Neale Lab consortium (replication data) were used for education and DIAGRAMplusMetabochip for T2DM.

RESULTS

The odds ratio for T2DM was 0.392 (95%CI: 0.263-0.583) per standard deviation increase (3.6 years) in education by the inverse variance weighted method, without heterogeneity or horizontal pleiotropy. Education was genetically associated with CHD, TG, BMI, WC, and WHR in the discovery phase, yet only the results for CHD, BMI, and WC were replicated in the replication data. Moreover, BMI was genetically associated with T2DM.

CONCLUSION

Short education was found to be associated with an increased T2DM risk. BMI might serve as a potential mediator between them.

Nicotine-mediated upregulation of microRNA-141 expression determines adipokine-intervened insulin resistance

MicroRNAs (miRNAs) are non-coding RNAs that are associated with adipokine homeostasis and insulin resistance. Whereas, smoking can disturb metabolic homeostasis. Present study was aimed to investigate the level of miRNA-141 in experimental animal model that were exposed with graded doses of nicotine. We further aimed to investigate the possible interplay of miRNA-141 expression change with adipokine homeostasis and occurrence of insulin resistance in nicotine-exposed experimental animals. Nicotine (0.5, 1.0, 3.0 and 6.0 mg/Kg) was administered to early adolescent; postnatal days ranging from 25 to 30 Wistar rats for one month. Serum was analyzed for leptin, adipokines, IL-6, MDA, HbA1c, insulin, G6PDH, hexokinase, and lipid profile. While miRNA-141 expression level was determined in plasma. Higher doses of nicotine were associated with higher glucose, HbA1c, leptin, IL-6, MDA and lipids levels, while, insulin, adiponectin, G6PDH, hexokinase and HDL levels were lower. Higher doses of nicotine also impaired glucose tolerance and exhibited significant increase in miR-141 expression signifying that nicotine exposure may influence adipokines regulation altering glycemic profile. This is accompanied with aggravated inflammatory responses where genetic expression of miRNA-141 can be an accessible biomarker for metabolic disturbances with insulin resistance and glucose intolerance.

Loss of Caveolin-1 Is Associated with a Decrease in Beta Cell Death in Mice on a High Fat Diet

Elevated free fatty acids (FFAs) impair beta cell function and reduce beta cell mass as a consequence of the lipotoxicity that occurs in type 2 diabetes (T2D). We previously reported that the membrane protein caveolin-1 (CAV1) sensitizes to palmitate-induced apoptosis in the beta pancreatic cell line MIN6. Thus, our hypothesis was that CAV1 knock-out (CAV1 KO) mice subjected to a high fat diet (HFD) should suffer less damage to beta cells than wild type (WT) mice. Here, we evaluated the in vivo response of beta cells in the pancreatic islets of 8-week-old C57Bl/6J CAV1 KO mice subjected to a control diet (CD, 14% kcal fat) or a HFD (60% kcal fat) for 12 weeks. We observed that CAV1 KO mice were resistant to weight gain when on HFD, although they had high serum cholesterol and FFA levels, impaired glucose tolerance and were insulin resistant. Some of these alterations were also observed in mice on CD. Interestingly, KO mice fed with HFD showed an adaptive response of the pancreatic beta cells and exhibited a significant decrease in beta cell apoptosis in their islets compared to WT mice. These in vivo results suggest that although the CAV1 KO mice are metabolically unhealthy, they adapt better to a HFD than WT mice. To shed light on the possible signaling pathway(s) involved, MIN6 murine beta cells expressing (MIN6 CAV) or not expressing (MIN6 Mock) CAV1 were incubated with the saturated fatty acid palmitate in the presence of mitogen-activated protein kinase inhibitors. Western blot analysis revealed that CAV1 enhanced palmitate-induced JNK, p38 and ERK phosphorylation in MIN6 CAV1 cells. Moreover, all the MAPK inhibitors partially restored MIN6 viability, but the effect was most notable with the ERK inhibitor. In conclusion, our results suggest that CAV1 KO mice adapted better to a HFD despite their altered metabolic state and that this may at least in part be due to reduced beta cell damage. Moreover, they indicate that the ability of CAV1 to increase sensitivity to FFAs may be mediated by MAPK and particularly ERK activation.

Nicotine triggers islet β cell senescence to facilitate the progression of type 2 diabetes

Cigarette smoking is a well-recognized risk factor for type 2 diabetes (T2DM), and may result in islet β cell damage and impaired insulin secretion. However, the underlying mechanisms remain largely elusive. In the present study, we demonstrated that nicotine induced premature senescence of pancreatic β cells in vitro and in vivo. The senescence-associated β-galactosidase (SA-β-Gal) assay showed that nicotine exposure induced apparent senescence phenotype of β-TC-6 cells at an initiating dose of 100 μM and starting from 12 h. In addition, 100 and 500 μM of nicotine exposure altered the expression of senescence marker proteins, such as p16, p19 and p21. Furthermore, we uncovered that the levels of intracellular Ca²⁺ and reactive oxygen species (ROS) were significantly elevated in β-TC-6 cells following exposure to 100 and 500 μM nicotine, while calcium channel blocker can reverse this effect. Furthermore, the senescence-inducing phenotype was confirmed in rat insulinoma INS-1 cells at a similar dose range, whereas blockade of nAChRs, calcium and ROS led to apparent impairment of senescence. Finally, we found that administration with 100 and 200 μg/mL nicotine in drinking water for 28 days significantly exacerbated aberrant glucose homeostasis in a mouse model of fat-induced T2DM. Of great intrigue, pancreatic β cells exhibited significantly enhanced senescence following nicotine administration. Taken together, this study suggests that premature senescence plays a pivotal role in nicotine-triggered β cell destruction and glucose intolerance, providing a theoretical basis for targeted prevention and treatment of smoking-induced T2DM.

Influence of SIRT1 polymorphisms for diabetic foot susceptibility and severity

The present study aimed to explore the influence of sirtuin 1 (SIRT1) polymorphisms (rs12778366 and rs3758391) on diabetic foot (DF) susceptibility and severity in patients with type 2 diabetes mellitus (T2DM).This case-control study recruited 142 patients with DF, 148 patients with T2DM, and 148 healthy controls. SIRT1 gene polymorphisms were sequenced by polymerase chain reaction (PCR) and direct sequencing method. The relative expression of SIRT1 mRNA was estimated using quantitative real-time PCR (qRT-PCR) assay. Odds ratio (OR) with 95% confidence interval (95% CI) were used to represent the association of SIRT1 polymorphisms with DF susceptibility and severity. The results were adjusted using logistic regression analysis.C allele of rs12778366 polymorphism was significantly correlated with reduced DF susceptibility which deriving from healthy controls (adjusted OR = 0.364, 95% CI = 0.158-0.835) so was patients with T2DM (P = .047, OR = 0.591, 95%CI = 0.349-0.998), but the results became nonsignificant adjusted by clinical features (adjusted OR = 0.654, 95% CI = 0.391-1.094). We failed to find any significant association between rs3758391 polymorphisms and T2DM, DF susceptibility. No significant association has been discovered between SIRT1 polymorphisms and DF severity or characteristics. In addition, compared to healthy control and T2DM cases, patients with DF exhibited significant downregulation of SIRT1. The 2 studied polymorphisms had no effects on its gene expression (P > .05 for all).SIRT1 rs12778366 polymorphism C allele might act as a protective factor for DF onset.