Search

Statins are primary drugs in the treatment of hyperlipidemias. This group of drugs is known for its beneficial pleiotropic effects (e.g., reduction of inflammatory state). However, a growing body of evidence suggests its diabetogenic properties. The culpable mechanism is not completely understood and might be related to the damage to pancreatic beta cells. Therefore, we conceived an in vitro study to explore the impact of atorvastatin on pancreatic islet beta cells line (1.1.E7). We evaluated the influence on viability, insulin, low-density lipoprotein (LDL) receptor, and proprotein convertase subtilisin/kexin type 9 (PCSK9) expression. A significant drop in mRNA for proinsulin and insulin expression was noted. Concurrently, a rise in LDL receptor at the protein level in cells exposed to atorvastatin was noted. Further experiments have shown that exenatide -belonging to glucagon-like peptide 1 (GLP-1) analogs that are used in a treatment of diabetes and known for its weight reducing properties -can alleviate the observed alterations. In this case, the mechanism of action of exenatide was dependent on a protein kinase A pathway. In conclusion, our results support the hypothesis that statin may have diabetogenic properties, which according to our study is related to reduced insulin expression. The concomitant use of GLP-1 receptor agonist seemed to successfully revert insulin expression. [ABSTRACT FROM AUTHOR]

Introduction. GLP-1 receptor agonists (e.g., exenatide) are novel drugs used in the treatment of diabetes. These drugs, working with other mechanisms of action, improve glycemic control by increasing secretion of insulin and improving survival of pancreatic islet beta cells. Alterations in the oxidative stress level or the expression of proteins associated with cholesterol uptake might be responsible for those findings. Currently, there are few in vitro studies on the impact of exenatide antioxidant capacity in human islet beta cell lines and none that assess the influence of exenatide on LDL receptors and PCSK9 under hyperglycemia and oxidative stress. Therefore, we evaluated the impact of exenatide on antioxidant capacity, insulin secretion, and proteins involved in cholesterol metabolism. Materials and Method. An in vitro culture of insulin-secreting cells 1.1E7 was subjected to hyperglycemia and oxidative stress. Assessment was made of the expression of enzymes associated with oxidative stress (NADPH oxidase, catalase, glutathione peroxidase, superoxide dismutase, iNOS) and cholesterol uptake (LDL receptors, PCSK9). Additionally, insulin and nitrite levels in culture media were quantified. Results. We showed that exenatide improves expression of catalase and reduces the amount of nitrite in cell cultures in a protein kinase A-dependent manner. Those results were accompanied by a drop in the expression of LDL receptors and PCSK9. Insulin secretion was modestly increased in the culture condition. Conclusions. Our findings show potential protective mechanisms exerted by exenatide in human insulin-secreting pancreatic beta cell line (1.1E7), which may be exerted through increased antioxidant capacity and reduced accumulation of cholesterol. [ABSTRACT FROM AUTHOR]

Reports have indicated that autoimmune bowel disorders affect an increasing number of people on every continent; therefore, it is important to better understand inflammatory bowel disease (IBD) and to explore new treatment options for patients suffering from it. Research has indicated the important role of enterocytes in IBD. Understanding the role of the intestinal epithelium in the pathogenesis of IBD may contribute to a better understanding of the inflammatory processes and aid in the identification of potential therapeutic treatments. The present study aimed to evaluate the effects of tofacitinib on Caco-2 cells cultured in an inflammatory environment induced using cytokines naturally found in patients with ulcerative colitis. Tofacitinib is an orally administered inhibitor of Janus kinases (JAKs) which, by modifying the JAK/STAT signaling pathway, reduces the effect of inflammatory cytokines in the gut. Caco-2 cells were used to model the intestinal epithelium and the culture conditions included the proinflammatory cytokine TNFα and tofacitinib. At the end of the culture period, enzymes involved in oxidative stress (superoxide dismutase 1, catalase, nicotinamide adenine dinucleotide phosphate), a marker of apoptosis (Bcl-2) and a key player in intracellular inflammatory signaling (nuclear factor κB) were assessed by quantitative PCR and western blotting. The in vitro phenotype of Caco-2 cells exposed to an inflammatory environment was observed to be similar to that observed in ulcerative colitis. Notably, tofacitinib was able to improve TNFα-induced changes in an in vitro model of ulcerative colitis, and a reduction in the activity of enzymes associated with oxidative stress was observed. In addition, tofacitinib-induced upregulation of Bcl-2 and claudin-1 may contribute to the beneficial effects of tofacitinib on the intestinal epithelium. Tofacitinib appears to have a protective effect on Caco-2 cells. Notably, in the present study, exposure to TNFα stimulated oxidative stress and apoptotic effects, and disrupted intercellular connectivity. The addition of tofacitinib decreased the activity of the examined parameters of oxidative and apoptotic stress, while increasing the activity of the parameter examined to evaluate the degree of intercellular connections. In conclusion, the inhibitory effects of tofacitinib on oxidative stress, as well as its anti-apoptotic and regenerative effects, provide important information regarding the positive effect of tofacitinib on Caco-2 cells, and therefore constitute potential information about the beneficial effect of the evaluated drug in UC. [ABSTRACT FROM AUTHOR]

GLP-1 agonists such as exenatide and liraglutide are novel drugs for the treatment of diabetes and obesity. While improvements in glycemic control can rely on an incretin effect, the mechanisms behind the loss of weight following therapy have yet to be completely elucidated, and seem to be associated with alterations in eating habits, resulting from changes in cytokines e.g. interleukin 1β (IL-1β) and oxidative signaling in the central nervous system (CNS). Increased levels of IL-1β and reactive oxygen species have been demonstrated to exert anorexigenic properties, and astrocytes appear to actively participate in maintaining the integrity of the CNS, which includes the paracrine secretion of inflammatory cytokines and involvement in the redox status. Therefore, the present study decided to explore the influence of exenatide [a glucagon-like peptide 1 (GLP-1 agonist)] on inflammatory and oxidative stress markers in cultured human astrocytes as a potential target for weight reduction therapies. In an experimental setting, normal human astrocytes were subjected to various glycemic conditions, including 40 mg/dl-hypoglycemic, 100 mg/dl-normoglycemic and 400 mg/dl-hyperglycemic, and exenatide, which is a GLP-1 agonist. The involvement of intracellular signaling by a protein kinase A (PKA) in the action of exenatide was estimated using a specific PKA inhibitor-PKI (14–22). The expression levels of IL-1β, nuclear factor kappa κB (NFκB), glial-fibrillary acidic protein (GFAP), p22 NADPH oxidase, glutathione peroxidase, catalase, superoxide dismutase 1, and reactive oxidative species were measured. The present study demonstrated that varying glucose concentrations in the culture media did not affect the protein expression or the level of reactive oxygen species. Conversely, exenatide led to an increase in IL-1β in normoglycemic culture conditions, which was accompanied by the increased expression of p22, glutathione peroxidase and the reduced expression of GFAP. Changes in the expression of IL-1β and p22 were dependent on the activation of PKA. The present study concluded that exenatide predominantly affected astrocytes in normoglycemic conditions, and hypothesize that this impact demonstrated one of novel mechanisms associated with astrocyte signaling that may contribute to weight loss. [ABSTRACT FROM AUTHOR]

A new peptide nucleic acid (PNA) mediated QPCR technique for the detection and quantification of the Multiple Sclerosis-Associated Retrovirus (MSRV) belonging to the human endogenous retrovirus-W (HERV-W) family has been developed. The assay utilizes a PNA probe which is fully complementary to the ERVWE1 sequence, another member of the HERV-W family which is closely related to MSRV. Due to its excellent affinity to a completely matched template, PNA probe selectively blocks the amplification of ERVWE1 thus allowing the specific and exclusive detection and quantification of the MSRV as PNA does not interfere with the amplification of MSRV. Using this newly developed method we found that MSRV is predominantly expressed over ERWVE1 in astrocyte-derived U-87 MG cell line but not in human umbilical vein endothelial cells or human placental cells. [ABSTRACT FROM AUTHOR]

Introduction: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a healthcare issue of growing concern. Its development is multifactorial, and it is more commonly seen in obese patients. In those circumstances, intracellular lipid overload ensues, resulting in oxidative stress that might be responsible for progression toward steatohepatitis. Novel therapeutic approaches that are effective in weight management are expected to improve the course of MASLD. One of the potential mechanisms involved in such protective properties may relate to the reduction in oxidative stress., Material and Methods: The induction of steatosis and the assessment of oxidative stress level and expression of antioxidant enzymes (superoxide dismutase - SOD, glutathione peroxidase - GPx and catalase - Cat) in HepG2 hepatoma cell line subjected to glucagon and exenatide treatment., Results: Exenatide monotherapy successfully reduced lipid accumulation by 25%. Significant reductions in markers of oxidative stress (reactive oxygen species and malondialdehyde) were obtained in cells subjected to combined treatment with glucagon and exenatide (by 24 and 21%, respectively). Reduced burden of oxidative stress was associated with elevated expression of SOD and GPx but not Cat., Conclusions: Combined activation of glucagon-like peptide-1 (GLP-1) and glucagon receptors reduces oxidative stress in HepG2 steatotic cell cultures. This observation may stem from increased antioxidative potential.