Regulatory role of NADPH oxidase in glycated LDL-induced upregulation of plasminogen activator inhibitor-1 and heat shock factor-1 in mouse embryo fibroblasts and diabetic mice

Nox4 as a novel therapeutic target for diabetic vascular complications

Diabetic vascular complications can affect both microvascular and macrovascular. Diabetic microvascular complications, such as diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and diabetic cardiomyopathy, are believed to be caused by oxidative stress. The Nox family of NADPH oxidases is a significant source of reactive oxygen species and plays a crucial role in regulating redox signaling, particularly in response to high glucose and diabetes mellitus. This review aims to provide an overview of the current knowledge about the role of Nox4 and its regulatory mechanisms in diabetic microangiopathies. Especially, the latest novel advances in the upregulation of Nox4 that aggravate various cell types within diabetic kidney disease will be highlighted. Interestingly, this review also presents the mechanisms by which Nox4 regulates diabetic microangiopathy from novel perspectives such as epigenetics. Besides, we emphasize Nox4 as a therapeutic target for treating microvascular complications of diabetes and summarize drugs, inhibitors, and dietary components targeting Nox4 as important therapeutic measures in preventing and treating diabetic microangiopathy. Additionally, this review also sums up the evidence related to Nox4 and diabetic macroangiopathy.

Bioactive Components and Health Benefits of Saskatoon Berry

In response to the recent rise in numbers of diabetes patients, many treatments have been developed; but currently, oral antihyperglycemic agents and insulin are still the main clinical treatments. Since current drugs have limitations and harmful side effects, research in alternative treatments has been sought. This article reviews recent research updates of Saskatoon berries (SB), covering its background information, its main active ingredients, its structure, and its function. Flavonoid compounds in Saskatoon berries, in particular flavanol, anthocyanin, and proanthocyanin, possess anti-inflammatory, antitumor, and antidiabetes impacts. The current review synthesizes the latest research on the health benefits of Saskatoon berry in a variety of domains. With further research, SB has the potential to help treat and prevent diabetes in the future.

Diabetic Cardiomyopathy: Impact of Biological Sex on Disease Development and Molecular Signatures

Diabetic cardiomyopathy refers to a unique set of heart-specific pathological variables induced by hyperglycemia and insulin resistance. Given that cardiovascular disease (CVD) is the leading cause of death in the world, and type 2 diabetes incidence continues to rise, understanding the complex interplay between these two morbidities and developing novel therapeutic strategies is vital. Two hallmark characteristics specific to diabetic cardiomyopathy are diastolic dysfunction and cardiac structural mal-adaptations, arising from cardiac cellular responses to the complex toxicity induced by hyperglycemia with or without hyperinsulinemia. While type 2 diabetes is more prevalent in men compared to women, cardiovascular risk is higher in diabetic women than in diabetic men, suggesting that diabetic women take a steeper path to cardiomyopathy and heart failure. Accumulating evidence from randomized clinical trials indicate that although pre-menopausal women have lower risk of CVDs, compared to age-matched men, this advantage is lost in diabetic pre-menopausal women, which suggests estrogen availability does not protect from increased cardiovascular risk. Notably, few human studies have assessed molecular and cellular mechanisms regarding similarities and differences in the progression of diabetic cardiomyopathy in men versus women. Additionally, most pre-clinical rodent studies fail to include female animals, leaving a void in available data to truly understand the impact of biological sex differences in diabetes-induced dysfunction of cardiovascular cells. Elegant reviews in the past have discussed in detail the roles of estrogen-mediated signaling in cardiovascular protection, sex differences associated with telomerase activity in the heart, and cardiac responses to exercise. In this review, we focus on the emerging cellular and molecular markers that define sex differences in diabetic cardiomyopathy based on the recent clinical and pre-clinical evidence. We also discuss miR-208a, MED13, and AT2R, which may provide new therapeutic targets with hopes to develop novel treatment paradigms to treat diabetic cardiomyopathy uniquely between men and women.

Regulation of the mammalian heat shock factor 1

Living organisms are endowed with the capability to tackle various forms of cellular stress due to the presence of molecular chaperone machinery complexes that are ubiquitous throughout the cell. During conditions of proteotoxic stress, the transcription factor heat shock factor 1 (HSF1) mediates the elevation of heat shock proteins, which are crucial components of the chaperone complex machinery and function to ameliorate protein misfolding and aggregation and restore protein homeostasis. In addition, HSF1 orchestrates a versatile transcriptional programme that includes genes involved in repair and clearance of damaged macromolecules and maintenance of cell structure and metabolism, and provides protection against a broad range of cellular stress mediators, beyond heat shock. Here, we discuss the structure and function of the mammalian HSF1 and its regulation by post-translational modifications (phosphorylation, sumoylation and acetylation), proteasomal degradation, and small-molecule activators and inhibitors.

Suppression of EC-SOD by oxLDL During Vascular Smooth Muscle Cell Proliferation

Reactive oxygen species (ROS) produced by endothelial cells and macrophages play important roles in atherogenesis because they promote the formation of oxidized low-density lipoproteins (oxLDL). Extracellular-superoxide dismutase (EC-SOD) is mainly produced by vascular smooth muscle cells (VSMCs), is secreted into the extracellular space, and protects cells from the damaging effects of the superoxide anion. Thus, the expression of EC-SOD in VSMCs is crucial for protecting cells against atherogenesis; however, oxLDL-induced changes in the expression of EC-SOD in VSMCs have not yet been examined. We herein showed that oxLDL decreased EC-SOD mRNA and protein levels by binding to lectin-like oxidized LDL receptor-1 (LOX-1). Moreover, we demonstrated the significant role of mitogen-activated protein kinase (MEK)/extracellular-regulated protein kinase (ERK) signaling in oxLDL-elicited reductions in the expression of EC-SOD and proliferation of VSMCs. The results obtained with the FCS treatment indicate that oxLDL-elicited reductions in the expression of EC-SOD are related to the proliferation of VSMCs. We herein showed for the first time that luteolin, a natural product, restored oxLDL-induced decreases in the expression of EC-SOD and proliferation of VSMCs. Collectively, the results of the present study suggest that oxLDL accelerates the development of atherosclerosis by suppressing the expression of EC-SOD and also that luteolin has potential as a treatment for atherosclerosis. J. Cell. Biochem. 117: 2496-2505, 2016. © 2016 Wiley Periodicals, Inc.

Effects of Saskatoon berry powder on monocyte adhesion to vascular wall of leptin receptor-deficient diabetic mice

HYPOTHESIS

Atherosclerotic cardiovascular complications are the leading cause of death in diabetic patients. Monocyte adhesion is an early event for atherogenesis. Previous studies demonstrated that dark-skin berries had cardiovascular protective effects. We hypothesize that Saskatoon berry (SB) powder may reduce monocyte adhesion in leptin receptor-deficient (db/db) diabetic mice.

METHODS

Wild-type and db/db mice were fed with chow or supplemented with SB powder. Anthocyanins in SB powder were identified using mass spectrometry. Mouse monocytes were incubated with mouse aorta. Monocyte adhesion was counted under microscopy. Inflammatory or metabolic markers in blood or tissue were analyzed using immunological or biochemical methods.

RESULTS

SB powder significantly reduced monocyte adhesion to aorta from diabetic db/db mice compared to regular chow. The increased monocyte adhesion to aorta was normalized in db/db mice treated with ≥5% of SB powder for 4 weeks. Increased contents of Nicotinamide adenine dinucleotide phosphate oxidase (NADPH) oxidase-4, heat shock factor-1, monocyte chemotactic protein (MCP)-1, intracellular adhesion molecule (ICAM)-1, P-selectin, tumor necrosis factor-α, plasminogen activator inhibitor (PAI)-1 and urokinase plasminogen activator in aorta or heart apex, elevated plasma PAI-1 and MCP-1 were detected in db/db mice on chow compared to wild-type mice on the same diet; 5% SB powder inhibited the increases of inflammatory, fibrinolytic or stress regulators in aorta or heart apex of db/db mice. Monocyte adhesion positively correlated with blood glucose, cholesterol, body weight, heart MCP-1, PAI-1 or ICAM-1.

CONCLUSION

The findings suggest that SB powder attenuated monocyte adhesion to aorta of db/db mice, which was potentially mediated through inhibiting the inflammatory, stress and/or fibrinolyic regulators.