Relationships among pancreatic beta cell function, the Nrf2 pathway, and IRS2: a cross-sectional study

Association between heme oxygenase-1 and hyperlipidemia in pre-diabetic patients: a cross-sectional study

Background

Although the importance and benefit of heme oxygenase-1 (HO-1) in diabetes rodent models has been known, the contribution of HO-1 in the pre-diabetic patients with hyperlipidemia risk still remains unclear. This cross-sectional study aims to evaluate whether HO-1 is associated with hyperlipidemia in pre-diabetes.

Methods

Serum level of HO-1 was detected using commercially available ELISA kit among 1,425 participants aged 49.3-63.9 with pre-diabetes in a multicenter Risk Evaluation of cAncers in Chinese diabeTic Individuals: A lONgitudinal (REACTION) prospective observational study. Levels of total cholesterol (TC) and triglyceride (TG) were measured and used to defined hyperlipidemia. The association between HO-1 and hyperlipidemia was explored in different subgroups.

Result

The level of HO-1 in pre-diabetic patients with hyperlipidemia (181.72 ± 309.57 pg/ml) was obviously lower than that in pre-diabetic patients without hyperlipidemia (322.95 ± 456.37 pg/ml). High level of HO-1 [(210.18,1,746.18) pg/ml] was negatively associated with hyperlipidemia (OR, 0.60; 95% CI, 0.37-0.97; p = 0.0367) after we adjusted potential confounding factors. In subgroup analysis, high level of HO-1 was negatively associated with hyperlipidemia in overweight pre-diabetic patients (OR, 0.50; 95% CI, 0.3-0.9; p = 0.034), especially in overweight women (OR, 0.42; 95% CI, 0.21-0.84; p = 0.014).

Conclusions

In conclusion, elevated HO-1 level was negatively associated with risk of hyperlipidemia in overweight pre-diabetic patients, especially in female ones. Our findings provide information on the exploratory study of the mechanism of HO-1 in hyperlipidemia, while also suggesting that its mechanism may be influenced by body weight and gender.

Lambda-cyhalothrin-induced pancreatic toxicity in adult albino rats

Lambda-cyhalothrin (LCT) is one of the most frequently utilized pyrethroids. This study aimed to explore the toxic effects of subacute exposure to LCT on the pancreas and the hepatic glucose metabolism in adult male albino rats. 20 rats were equally grouped into; Control group and LCT group. The latter received LCT (61.2 mg/kg b.wt.), orally on a daily basis for 28 days. At the end of experiment, blood samples were collected for the determination of serum glucose and insulin levels. Pancreases were harvested and levels of malondialdehyde (MDA); catalase (CAT); superoxide dismutase (SOD); reduced glutathione (GSH); tumor necrosis factor-α (TNF-α); interleukin-6 (IL-6); nuclear factor erythroid 2-related factor 2 (Nrf2); heme oxygenase 1 (HO-1); and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) were assessed. Also, liver samples were analyzed for the activity of glucose metabolism enzymes, glycogen content, and pyruvate and lactate concentrations. Histopathological and immunohistochemical examinations of pancreatic tissues were undertaken as well. Results revealed hyperglycemia, hypoinsulinemia, increased MDA, TNF-α, IL-6, and NF-κB levels, in association with reduced CAT, SOD, GSH, Nrf2, and HO-1 levels in LCT group. Liver analyses demonstrated a clear disturbance in the hepatic enzymes of glucose metabolism, diminished glycogen content, decreased pyruvate, and increased lactate concentrations. Besides, pancreatic islets displayed degenerative changes and β-cells loss. Immunohistochemistry revealed diminished area percentage (%) of insulin and Nrf2 and increased TNF-α immunoreaction. In conclusion, subacute exposure to LCT induces pancreatic toxicity, mostly via oxidative and inflammatory mechanisms, and dysregulates hepatic glucose metabolism in albino rats.

Citrus flavanone metabolites significantly modulate global proteomic profile in pancreatic β-cells under high-glucose-induced metabolic stress

Hesperidin and narirutin are the major citrus flavanones. Several studies have associated these compounds with pancreatic β-cell survival through their capacity to reduce oxidative stress, inflammation, and inhibit apoptosis. However, the molecular mechanisms of action of flavanones in pancreatic β-cells under high-glycemic stress is still largely unknown. Therefore, this study aimed to decipher molecular mechanisms of flavanone metabolites in pancreatic β-cells treated with high glucose concentration using untargeted shotgun proteomics. We identified 569 proteins differentially expressed in cells exposed to hesperetin 7-glucuronide (H7G) and 265 in cells exposed to 3-(4'-hydroxyphenyl) propanoic acid (PA). Comparison of global proteomic profiles suggest that these metabolites could counteract changes in protein expression induced by high glucose stress. The bioinformatic analyses suggested that H7G and PA modulated the expression of proteins involved in cell adhesion, cell signaling, metabolism, inflammation, and protein processing in endoplasmic reticulum (ER) pathways. Taken together, this study suggests that H7G and PA can modulate the expression of proteins that may prevent dysfunction of pancreatic β-cells under stress induced by high glucose.

The Positive Effect of 6-Gingerol on High-Fat Diet and Streptozotocin-Induced Prediabetic Mice: Potential Pathways and Underlying Mechanisms

The purposes of the present work are to assess how 6-gingerol (6G) positively influences serum glucose regulation in mice with prediabetes triggered by streptozotocin (STZ) plus a high-fat diet (HFD) and to clarify its underlying mechanisms. An analysis of prediabetic symptoms and biochemical characteristics found that 6G intervention was significantly associated with reduced fasting glucose levels, alleviated insulin resistance, better glucose tolerance, hepatic and pancreatic impairment, and dyslipidemia. For the recognition of the target gut microbiota and the pathways linked to 6G's hypoglycemic function, a combination of hepatic RNA and 16S rRNA sequencing was employed. Specifically, 6G significantly improved the dysbiosis of the gut microbiota and elevated the relative abundances of Alistipes, Alloprevotella, and Ruminococcus_1. Furthermore, 6G supplementation inhibited gluconeogenesis and stimulated glycolysis by activating the PI3K/AKT axis, which also repressed the oxidative stress through Nrf2/Keap1-axis initiation. In addition, Spearman's correlation analyses reveal a complex interdependency set among the gut microbiota, metabolic variables, and signaling axes. Taken together, the hypoglycemic effect of 6G is partially mediated by altered gut microbiota, as well as by activated Nrf2/Keap1 and PI3K/AKT axes. Thus, 6G may be used as a candidate dietary supplement for relieving prediabetes.

Dysregulation of β-Cell Proliferation in Diabetes: Possibilities of Combination Therapy in the Development of a Comprehensive Treatment

Diabetes mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia as a result of insufficient insulin levels and/or impaired function as a result of autoimmune destruction or insulin resistance. While Type 1 DM (T1DM) and Type 2 DM (T2DM) occur through different pathological processes, both result in β-cell destruction and/or dysfunction, which ultimately lead to insufficient β-cell mass to maintain normoglycemia. Therefore, therapeutic agents capable of inducing β-cell proliferation is crucial in treating and reversing diabetes; unfortunately, adult human β-cell proliferation has been shown to be very limited (~0.2% of β-cells/24 h) and poorly responsive to many mitogens. Furthermore, diabetogenic insults result in damage to β cells, making it ever more difficult to induce proliferation. In this review, we discuss β-cell mass/proliferation pathways dysregulated in diabetes and current therapeutic agents studied to induce β-cell proliferation. Furthermore, we discuss possible combination therapies of proliferation agents with immunosuppressants and antioxidative therapy to improve overall long-term outcomes of diabetes.

The Role of Oxidative Stress in Pancreatic β Cell Dysfunction in Diabetes

Diabetes is a chronic metabolic disorder characterized by inappropriately elevated glucose levels as a result of impaired pancreatic β cell function and insulin resistance. Extensive studies have been conducted to elucidate the mechanism involved in the development of β cell failure and death under diabetic conditions such as hyperglycemia, hyperlipidemia, and inflammation. Of the plethora of proposed mechanisms, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, and oxidative stress have been shown to play a central role in promoting β cell dysfunction. It has become more evident in recent years that these 3 factors are closely interrelated and importantly aggravate each other. Oxidative stress in particular is of great interest to β cell health and survival as it has been shown that β cells exhibit lower antioxidative capacity. Therefore, this review will focus on discussing factors that contribute to the development of oxidative stress in pancreatic β cells and explore the downstream effects of oxidative stress on β cell function and health. Furthermore, antioxidative capacity of β cells to counteract these effects will be discussed along with new approaches focused on preserving β cells under oxidative conditions.