Type 2 diabetes is a heterogeneous disorder that develops as a result of relatively inappropriate insulin secretion and insulin resistance. Increased levels of free fatty acids (FFAs) are one of the important factors for the pathogenesis of type 2 diabetes and contribute to defective β -cell proliferation and increased β -cell apoptosis. Recently, glucagon-like peptide-1 (GLP-1) receptor agonists have been shown to possess an antiapoptotic effect, by increasing β -cell mass and improving β -cell function. However, their effects on β -cells in vitro against lipotoxicity have not been elucidated completely. In this study, we investigated whether the GLP-1 receptor agonist exendin-4 displays prosurvival effects in pancreatic β -cells exposed to chronic elevated FFAs. Results showed that exendin-4 inhibited apoptosis induced by palmitate in MIN6 cells. After 24 h of incubation, exendin-4 caused rapid activation of extracellular signal-related kinase 1/2 (ERK1/2) under lipotoxic conditions. The ERK1/2 inhibitor PD98059 blocked the antilipotoxic effect of exendin-4 on MIN6 cells. Exendin-4 also inhibited the mitochondrial pathway of apoptosis. This inhibition is associated with upregulation of BCL-2. Our findings suggested that exendin-4 may exert cytoprotective effects through activation of ERK1/2 and inhibition of the mitochondrial apoptosis pathway.
As Th22 subsets are identified, their involvement in the pathogenesis of numerous autoimmune diseases has become apparent. In this study, we investigated differentiation of Th22 cells in the autoimmune thyroid diseases including Hashimoto's thyroiditis (HT) and Graves' disease (GD). Besides, we also explored the involvement of Th22 cells in an iodine-induced autoimmune thyroiditis (AIT) model (i.e., NOD.H-2(h4) mice). In HT patients, we showed the level of circulating Th22 cells correlated with the level of serum IL-22, and was significantly higher than in GD patients and healthy control subjects. Levels of serum IL-6, a major Th22 cell differentiation effector, were also higher in HT, and correlated with Th22 cells concentration. Peripheral blood mononuclear cells isolated from HT patients produced larger amounts of IL-6 in vitro than did those isolated from other groups. Furthermore, unlike those from GD patients, T lymphocytes from HT patients showed an enhanced differentiation in vitro into Th22 cells in the presence of recombinant IL-6 and TNF-α. In addition, levels of circulating Th22 cells and titers of thyroid peroxidase antibody were positively correlated in HT patients. In NOD.H-2(h4) mice, higher numbers of Th22 cells were observed in the spleens of the AIT group, while splenocytes of this group also produced larger amounts of IL-6 and IL-22 in vitro compared with the control. Intra-thyroid infiltrating IL-22+ lymphocytes were significantly increased in mice of the AIT group compared with the control. Our results indicate that Th22 cells may contribute to the pathogenesis of HT.
Background: Efficient and targeted delivery of cytotoxic drugs is still a challenge in the fight against cancer. Ultrasound-targeted destruction of cytotoxic drug-loaded lipid microbubbles (LMs) might be a promising method. This study aimed to explore the antitumor effects of docetaxel-loaded LM (DLLM) combined with ultrasound-targeted microbubble destruction (UTMD) on liver cancer. Materials and methods: DLLMs were made by a mechanical vibration technique. The effects of docetaxel, DLLM alone, and DLLM + UTMD on cell viability and cell proliferation (Cell Counting Kit-8 assay) of MHCC-H cells and HepG2 cells were tested. The effects on cell cycle (flow cytometry) and apoptosis (flow cytometry and immunoblotting) of MHCC-H cells were tested. Solid fast-growing tumor mouse models were established and were randomized to blank LM + UTMD (controls) or DLLM + UTMD. Tumor volume was compared between the two groups. Results: DLLMs had an 18%±7% drug-loading capacity, an 80%±3% encapsulation efficiency, and a mean particle size of 2,845 nm (75% range 1,527–5,534 nm). Compared to the other groups, DLLM + UTMD decreased the proliferation and increased the apoptosis of MHCC-H cells. DLLM + UTMD resulted in the inhibition of a higher proportion of cells in the G1 phase. Compared to the control group, the tumor volume in mice receiving DLLM + UTMD was smaller. Conclusion: DLLM + UTMD can increase the proportion of cells arrested in the G1 phase, decrease tumor cell proliferation, and induce MHCC-H cell apoptosis. The growth of solid tumors in mice was inhibited. These results could provide a novel targeted strategy against liver cancer. Keywords: lipid microbubble, liver cancer, docetaxel, ultrasound-triggered drug delivery
Abstract Liraglutide, a glucagon-like peptide (GLP-1) receptor agonist, has showed favorable effects in the glycaemic control and weight reduction in patients with type 2 diabetes mellitus (T2DM). The meta-analysis was to compare the efficacy and safety of liraglutide added to metformin with other treatments in patients with T2DM. A systematic literature search on PubMed, Embase, Web of Science and the Cochrane library databases were performed. Eligible studies were randomized controlled trials (RCTs) of patients with T2DM who received the combination treatment of liraglutide and metformin. Pooled estimates were performed using a fixed-effects model or random-effects model. A total of nine RCTs met the inclusion criteria. Compared with control (placebo, sitagliptin, glimepiride, dulaglutide, insulin glargine, and NPH), liraglutide in combination with metformin resulted in significant reductions in HbA1c, bodyweight, FPG, and PPG, and similar reductions in SBP, and DBP. Moreover, liraglutide combined with metformin did not increase the risk of hypoglycemia, but induced a higher incidence of gastrointestinal disorders. In conclusion, this meta-analysis confirmed the use of liraglutide as add-on to metformin appeared to be effective and safe for patients with T2DM. However, considering the potential limitations in this study, more large-scale, well-conducted RCTs are needed to identify our findings.
To investigate the protective effect of insulin on burn serum-challenged cardiomyocytes in vitro.Primary culture of cardiomyocytes from Sprague-Dawley (SD) 2-day-old neonate rats were divided into sham group, burn group, insulin group, and insulin activation inhibitor LY294002 pretreatment group (LY group). The model of cardiomyocytes injury induced by burn serum of 3-month-old SD rats [the serum of abdominal aortic was collected at 6 hours after modelling 30% total surface area (TBSA) III degree scald rat] was reproduced. In the insulin group, 10% burn serum and insulin (10 U/L) were added into cell culture medium, and in the LY group, LY294002 (50 μmol/L) was pretreated for 30 minutes before the addition of burn serum and insulin. Sham group was only given 10% serum of sham injured rats (sham rats were only placed in 37 centigrade warm water). After the cells were cultured for 12 hours, the release of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and creatine kinase (CK) were determined by enzyme-linked immunosorbent assay (ELISA). The cardiac troponin T (cTnT) protein expression was examined by Western Blot. Apoptosis of cardiomyocytes was observed after Hoechst 33258 staining.Compared with the sham group, the cardiomyocytes were damaged and released inflammatory cytokines after burn serum-challenged. The levels of TNF-α, IL-6 and CK increased [TNF-α (ng/L): 273±48 vs. 21±6, IL-6 (ng/L): 416±83 vs. 44±11, CK (U/L): 1.44±0.24 vs. 0.14±0.08, all P < 0.01], while the expression of cTnT protein decreased (cTnT/β-actin: 0.12±0.04 vs. 0.86±0.34, P < 0.01), and the cardiomyocyte apoptosis increased [(19.1±5.6)% vs. (5.2±1.3)%, P < 0.01]. Insulin could significantly reduce the damage of cardiomyocytes, decrease the release of TNF-α, IL-6 and CK induced by burn serum [TNF-α (ng/L): 105±37 vs. 273±48, IL-6 (ng/L): 176±77 vs. 416±83, CK (U/L): 0.82±0.26 vs. 1.44±0.24, all P < 0.05], the expression of cTnT protein significantly increased (cTnT/β-actin: 0.41±0.16 vs. 0.12±0.04, P < 0.05), and the cells apoptosis rate significantly decreased [(10.7±3.2)% vs. (19.1±5.6)%, P < 0.05]. Further blocking experiments showed that LY294002 could mitigate the protective effects of insulin.For cardiomyocytes challenged by burn serum, insulin may decrease inflammation, apoptosis and then protect the cardiomyocytes.
Nuclear factor E2–related factor 2 (Nrf2) is a transcription factor that functions as a master regulator of the cellular adaptive response to oxidative stress. Our previous studies showed that Nrf2 plays a critical role in adipogenesis by regulating expression of CCAAT/enhancer-binding protein β and peroxisome proliferator–activated receptor γ. To determine the role of Nrf2 in the development of obesity and associated metabolic disorders, the incidence of metabolic syndrome was assessed in whole-body or adipocyte-specific Nrf2-knockout mice on a leptin-deficient ob/ob background, a model with an extremely positive energy balance. On the ob/ob background, ablation of Nrf2, globally or specifically in adipocytes, led to reduced white adipose tissue (WAT) mass, but resulted in an even more severe metabolic syndrome with aggravated insulin resistance, hyperglycemia, and hypertriglyceridemia. Compared with wild-type mice, WAT of ob/ob mice expressed substantially higher levels of many genes related to antioxidant response, inflammation, adipogenesis, lipogenesis, glucose uptake, and lipid transport. Absence of Nrf2 in WAT resulted in reduced expression of most of these factors at mRNA or protein levels. Our findings support a novel role for Nrf2 in regulating adipose development and function, by which Nrf2 controls the capacity of WAT expansion and insulin sensitivity and maintains glucose and lipid homeostasis.
The transcription factor nuclear factor erythroid 2-like 1 (NFE2L1 or NRF1) is involved in various critical cell processes such as maintenance of ubiquitin-proteasome system and regulation of the cellular antioxidant response. We previously determined that pancreatic β-cell-specific Nfe2l1-knockout mice had hyperinsulinemia and that silencing of Nfe2l1 in mouse islets or MIN6 insulinoma β-cells induced elevated basal insulin release and altered glucose metabolism. Hypoglycemia is a major issue with aggressive insulinomas, although a role of NFE2L1 in this pathology is not defined. In the present work, we studied the tumorigenicity of Nfe2l1-deficient insulinoma MIN6 cells (Nfe2l1-KD) and sensitivity to chemotherapy. Nfe2l1-KD cells grew faster and were more aggressive than Scramble cells in vitro In a mouse allograft transplantation model, insulinomas arising from Nfe2l1-KD cells were more aggressive and chemoresistant. The conclusion was amplified using streptozotocin (STZ) administration in an allograft transplantation model in diabetic Akita background mice. Furthermore, Nfe2l1-KD cells were resistant to damage by the chemotherapeutic drugs STZ and 5-fluorouracil, which was linked to binding of hexokinase 1 with mitochondria, enhanced mitochondrial membrane potential and closed mitochondrial potential transition pore. Overall, both in vitro and in vivo data from Nfe2l1-KD insulinoma cells provided evidence of a previously un-appreciated action of NFE2L1 in suppression of tumorigenesis. Nfe2l1 silencing desensitizes insulinoma cells and derived tumors to chemotherapeutic-induced damage, likely via metabolic reprograming. These data indicate that NFE2L1 could potentially play an important role in the carcinogenic process and impact chemosensitivity, at least within a subset of pancreatic endocrine tumors.
Oxidative stress is implicated in the pathogenesis of pancreatic β -cell dysfunction that occurs in both type 1 and type 2 diabetes. Nuclear factor E2-related factor 2 (NRF2) is a master regulator in the cellular adaptive response to oxidative stress. The present study found that MIN6 β -cells with stable knockdown of Nrf2 ( Nrf2 -KD) and islets isolated from Nrf2 -knockout mice expressed substantially reduced levels of antioxidant enzymes in response to a variety of stressors. In scramble MIN6 cells or wild-type islets, acute exposure to oxidative stressors, including hydrogen peroxide (H 2 O 2 ) and S-nitroso-N-acetylpenicillamine, resulted in cell damage as determined by decrease in cell viability, reduced ATP content, morphology changes of islets, and/or alterations of apoptotic biomarkers in a concentration- and/or time-dependent manner. In contrast, silencing of Nrf2 sensitized MIN6 cells or islets to the damage. In addition, pretreatment of MIN6 β -cells with NRF2 activators, including CDDO-Im, dimethyl fumarate (DMF), and tert -butylhydroquinone (tBHQ), protected the cells from high levels of H 2 O 2 -induced cell damage. Given that reactive oxygen species (ROS) are involved in regulating glucose-stimulated insulin secretion (GSIS) and persistent activation of NRF2 blunts glucose-triggered ROS signaling and GSIS, the present study highlights the distinct roles that NRF2 may play in pancreatic β -cell dysfunction that occurs in different stages of diabetes.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)