Oxidative stress in cardiac and skeletal muscle dysfunction associated with diabetes mellitus

Simultaneous Administration of Berberine and Transplantation of Endometrial Stem Cell-Derived Insulin Precursor Cells on a Nanofibrous Scaffold to Treat Diabetes Mellitus in Mice

Today, significant success has been achieved in treating diabetes with cell therapy derived from various sources of stem and progenitors. The replacement of beta cells is one of the new diabetes treatment methods. To this end, the production of pancreatic beta precursors in cell culture has created an important research field for diabetes treatment. Endometrial stem cells were isolated using an enzymatic method, and after their identity was confirmed using a flow cytometry and differentiation potential assay, the isolated cells were cultured on an electrospun PCL/CS scaffold. Endometrial cells were differentiated into insulin-producing cells (IPCs), and gene expression was analyzed using the qRT-PCR and immunofluorescence to confirm the creation of IPCs. Then, IPCs on the scaffold along with berberine were applied to 5 groups of diabetic mice, and after 6 weeks, insulin, blood glucose, and weight of the animals were measured. The findings revealed that pancreatic markers were significantly expressed in IPCs compared to control cells. In addition, when compared to the control group and scaffolds, the receiving group of IPCs on scaffolds had a significant improvement (p ≤ 0.0015), and this improvement increased with the addition of berberine (decrease in blood sugar (133 mg/dL), and an increase in weight (5/39 g) and insulin (2.29 MIU/L). Thus, tissue engineering is a promising new strategy for treating diabetes and can be used in the future for cell therapy and suitable drugs for diabetic patients.

Understanding diabetes-induced cardiomyopathy from the perspective of renin angiotensin aldosterone system

Experimental and clinical evidence suggests that diabetic subjects are predisposed to a distinct cardiovascular dysfunction, known as diabetic cardiomyopathy (DCM), which could be an autonomous disease independent of concomitant micro and macrovascular disorders. DCM is one of the prominent causes of global morbidity and mortality and is on a rising trend with the increase in the prevalence of diabetes mellitus (DM). DCM is characterized by an early left ventricle diastolic dysfunction associated with the slow progression of cardiomyocyte hypertrophy leading to heart failure, which still has no effective therapy. Although the well-known "Renin Angiotensin Aldosterone System (RAAS)" inhibition is considered a gold-standard treatment in heart failure, its role in DCM is still unclear. At the cellular level of DCM, RAAS induces various secondary mechanisms, adding complications to poor prognosis and treatment of DCM. This review highlights the importance of RAAS signaling and its major secondary mechanisms involving inflammation, oxidative stress, mitochondrial dysfunction, and autophagy, their role in establishing DCM. In addition, studies lacking in the specific area of DCM are also highlighted. Therefore, understanding the complex role of RAAS in DCM may lead to the identification of better prognosis and therapeutic strategies in treating DCM.

Amelioration of diabetes-induced inflammation mediated pyroptosis, sarcopenia, and adverse muscle remodelling by bone morphogenetic protein-7

BACKGROUND

Diabetic myopathy involves hyperglycaemia and inflammation that causes skeletal muscle dysfunction; however, the potential cellular mechanisms that occur between hyperglycaemia and inflammation, which induces sarcopenia, and muscle dysfunction remain unknown. In this study, we investigated hyperglycaemia-induced inflammation mediating high-mobility group box 1 activation, which is involved in a novel form of cell death, pyroptosis, diabetic sarcopenia, atrophy, and adverse muscle remodelling. Furthermore, we investigated the therapeutic potential of bone morphogenetic protein-7 (BMP-7), an osteoporosis drug, to treat pyroptosis, and diabetic muscle myopathy.

METHODS

C57BL6 mice were treated with saline (control), streptozotocin (STZ), or STZ + BMP-7 to generate diabetic muscle myopathy. Diabetes was established by determining the increased levels of glucose. Then, muscle function was examined, and animals were sacrificed. Gastrocnemius muscle or blood samples were analysed for inflammation, pyroptosis, weight loss, muscle atrophy, and adverse structural remodelling of gastrocnemius muscle using histology, enzyme-linked immunosorbent assay, immunohistochemistry, western blotting, and reverse transcription polymerase chain reaction.

RESULTS

A significant (P < 0.05) increase in hyperglycaemia leads to an increase in inflammasome (high-mobility group box 1, toll-like receptor-4, and nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain containing protein 3) formation in diabetic muscle cells. Further analysis showed an up-regulation of the downstream pyroptotic pathway with significant (P < 0.05) number of positive muscle cells expressing pyroptosis-specific markers [caspase-1, interleukin (IL)-1β, IL-18, and gasdermin-D]. Pyroptotic cell death is involved in further increasing inflammation by releasing pro-inflammatory cytokine IL-6. Structural analysis showed the loss of muscle weight, decreased myofibrillar area, and increased fibrosis leading to muscle dysfunction. Consistent with this finding, BMP-7 attenuated hyperglycaemia (~50%), pyroptosis, inflammation, and diabetic adverse structural modifications as well as improved muscle function.

CONCLUSIONS

In conclusion, we report for the first time that increased hyperglycaemia and inflammation involve cellular pyroptosis that induces significant muscle cell loss and adverse remodelling in diabetic myopathy. We also report that targeting pyroptosis with BMP-7 improves diabetic muscle pathophysiology and muscle function. These findings suggest that BMP-7 could be a potential therapeutic option to treat diabetic myopathy.

Pathway attenuation of fatty acid beta-oxidation in the skeletal muscle of a type 2 diabetic mouse model

RATIONALE

Whether catabolic abnormalities of fatty acids exist in the skeletal muscle of type 2 diabetes mellitus (T2DM) has not been determined. In this study, we postulated that a systematic evaluation of the protein abundance and metabolic activity related to fatty acids in the skeletal muscle tissues of a T2DM mouse model was feasible to address this question.

METHODS

Mitochondria were extracted from wild-type (WT) and db/db mice followed by quantitative analysis of the proteins involved in mitochondrial fatty acid oxidation (mFAO). The pathway activity of mFAO in skeletal muscle tissues was monitored in vitro using mass spectrometry, and tissue lipidomic analysis was conducted in profiling and target mode to distinguish the levels of long-chain acylcarnitines between WT and db/db mice.

RESULTS

Two proteins related to the mFAO pathway were significantly downregulated in the skeletal muscle mitochondria of db/db mice. The measurement of mFAO pathway activity in vitro revealed that the abundance of long-chain acylcarnitines (C14 to C18) in db/db mice was lower than that in WT mice, and the determination of acylcarnitines in skeletal muscle tissues in vivo revealed that most long-chain acylcarnitines were decreased in db/db mice.

CONCLUSIONS

The findings of lower abundance of ACAD9 and CPT1B, reduced activity of the mFAO pathway in vitro and decreased acylcarnitines in vivo firmly support that the mFAO pathway in the skeletal muscle of diabetic mice is attenuated, possibly resulting in cell/tissue dysfunction in diabetes.

Nutritional Aspects in Diabetic CKD Patients on Tertiary Care

Background and objectives: Diabetes is largely prevalent in the chronic kidney disease (CKD) population. Both conditions have metabolic and nutritional abnormalities that affect body composition and the presence of diabetes makes the dietary management of CKD patients more difficult. The aim of this study was to assess peculiar nutritional and functional aspects of diabetic patients in an adult/elderly CKD population, and their predictive significance. Materials and methods: This prospective cohort study included 144 out-patients aged >55 years, affected by stage 3b-4 CKD, on tertiary care clinic; 48 (40 males) were type 2 diabetics and 96 (80 males) were nondiabetics. The two groups have similar age, gender, and residual renal function (30 ± 9 vs. 31 ± 11 mL/min×1.73). All patients underwent a comprehensive nutritional and functional assessment and were followed for 31 ± 14 months. Results: Diabetic CKD patients showed higher waist circumference and fat body mass, lower muscle mass, and lower number of steps per day and average daily METs. Meanwhile, resting energy expenditure (REE), as assessed by indirect calorimetry, and dietary energy intake were similar as well as hand-grip and 6 min walking test. Diabetic patients did not show a greater risk for all-cause mortality and renal death with respect to nondiabetics. Middle arm muscle circumference, phase angle, serum cholesterol, and serum albumin were negatively related to the risk of mortality and renal death after adjustment for eGFR. Conclusions: CKD diabetic patients differed from nondiabetics for a greater fat mass, lower muscle mass, and lower physical activity levels. This occurred at the same REE and dietary energy intake. The outcome of diabetic or nondiabetic CKD patients on tertiary care management was similar in terms of risk for mortality or renal death. Given the same residual renal function, low levels of muscle mass, phase angle, serum albumin, and cholesterol were predictive of poor outcome. Overall, a malnutrition phenotype represents a major predictor of poor outcome in diabetic and nondiabetic CKD patients.

A Short-Term High-Fat Diet Alters Glutathione Levels and IL-6 Gene Expression in Oxidative Skeletal Muscles of Young Rats

Obesity and ensuing disorders are increasingly prevalent worldwide. High-fat diets (HFD) and diet-induced obesity have been shown to induce oxidative stress and inflammation while altering metabolic homeostasis in many organs, including the skeletal muscle. We previously observed that 14 days of HFD impairs contractile functions of the soleus (SOL) oxidative skeletal muscle. However, the mechanisms underlying these effects are not clarified. In order to determine the effects of a short-term HFD on skeletal muscle glutathione metabolism, young male Wistar rats (100–125 g) were fed HFD or a regular chow diet (RCD) for 14 days. Reduced (GSH) and disulfide (GSSG) glutathione levels were measured in the SOL. The expression of genes involved in the regulation of glutathione metabolism, oxidative stress, antioxidant defense and inflammation were measured by RNA-Seq. We observed a significant 25% decrease of GSH levels in the SOL muscle. Levels of GSSG and the GSH:GSSG ratio were similar in both groups. Further, we observed a 4.5 fold increase in the expression of pro-inflammatory cytokine interleukin 6 (IL-6) but not of other cytokines or markers of inflammation and oxidative stress. We hereby demonstrate that a short-term HFD significantly lowers SOL muscle GSH levels. This effect could be mediated through the increased expression of IL-6. Further, the skeletal muscle antioxidant defense could be impaired under cellular stress. We surmise that these early alterations could contribute to HFD-induced insulin resistance observed in longer protocols.

Aging, physical activity, and diabetic complications related to loss of muscle strength in patients with type 2 diabetes

Patients with type 2 diabetes may have motor dysfunctions such as loss of muscle strength. Compared with non-diabetic subjects, patients with diabetes show decreased lower extremity muscle strength. The aim of this review was to describe the influence of factors associated with loss of muscle strength in patients with type 2 diabetes. Aging promotes an accelerated loss of muscle strength in patients with diabetes. Physical inactivity may cause a decline in muscle strength in patients with diabetes. Gradual loss of muscle strength is related to the presence and severity of diabetic neuropathy. Diabetic nephropathy may be a factor contributing to loss of muscle strength, because decrease in skeletal muscle mass is a hallmark of end-stage renal disease. Resistance exercise is an essential component of diabetes treatment regimens and also plays a role in the prevention and management of sarcopenia. Intensive physical therapy intervention should be provided to patients with diabetes having decreased muscle strength.

Recovery of Cardiac Remodeling and Dysmetabolism by Pancreatic Islet Injury Improvement in Diabetic Rats after Yacon Leaf Extract Treatment

Yacon (Smallanthus sonchifolius) is a native Andean plant rich in phenolic compounds, and its effects on dysmetabolism and cardiomyopathy in diabetic rats was evaluated. The rats (10/group) were allocated as follows: C, controls; C + Y, controls treated with Yacon leaf extract (YLE); DM, diabetic controls; and DM + Y, diabetic rats treated with YLE. Type 1 diabetes (T1DM) was induced by the administration of streptozotocin (STZ; 40 mg⁻¹/kg body weight, single dose, i.p.), and treated groups received 100 mg/kg body weight YLE daily via gavage for 30 d. The YLE group shows an improvement in dysmetabolism and cardiomyopathy in the diabetic condition (DM versus DM + Y) promoting a significant reduction of glycemia by 63.39%, an increase in insulin concentration by 49.30%, and a decrease in serum triacylglycerol and fatty acid contents by 0.39- and 0.43-fold, respectively, by ameliorating the pancreatic islet injury, as well as increasing the activity of the antioxidant enzymes (catalase, superoxide dismutase, and glutathione peroxidase) and decreasing the fibrosis and cellular disorganization in cardiac tissue. The apparent benefits of YLE seem to be mediated by ameliorating dysmetabolism and oxidative stress in pancreatic and cardiac tissues.

Influence of the PDE5 inhibitor tadalafil on redox status and antioxidant defense system in C2C12 skeletal muscle cells

Phosphodiesterase type 5 inhibitors (PDE5Is), widely known for their beneficial effects onto male erectile dysfunction, seem to exert favorable effects onto metabolism as well. Tadalafil exposure increases oxidative metabolism of C2C12 skeletal muscle cells. A rise in fatty acid (FA) metabolism, requiring more oxygen, could induce a larger reactive oxygen species (ROS) release as a byproduct thus leading to a redox imbalance. The aim of this study was to determine how PDE5I tadalafil influences redox status in skeletal muscle cells to match the increasing oxidative metabolism. To this purpose, differentiated C2C12 skeletal muscle cells were treated with tadalafil and analyzed for total antioxidant capacity (TAC) and glutathione levels as marker of redox status; enzyme activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) engaged in antioxidant defense; and lipid peroxidation (TBARS) and protein carbonyls (PrCar) as markers of oxidative damage. Tadalafil increased total intracellular glutathione (tGSH), CAT, SOD, and GPx enzymatic activities while no changes were found in TAC. A perturbation of redox status, as showed by the decrease in the ratio between reduced/oxidized glutathione (GSH/GSSG), was observed. Nevertheless, it did not cause any change in TBARS and PrCar levels probably due to the enhancement in the antioxidant enzymatic network. Taken together, these data indicate that tadalafil, besides improving oxidative metabolism, may be beneficial to skeletal muscle cells by enhancing the enzymatic antioxidant system capacity.

Metabolomics – the complementary field in systems biology: a review on obesity and type 2 diabetes

This paper highlights the metabolomic roles in systems biology towards the elucidation of metabolic mechanisms in obesity and type 2 diabetes.

Oxidative stress and cardiovascular health: therapeutic potential of polyphenols

Reactive oxygen species (ROS) are important in normal cellular function and physiology. However, oxidative stress resulting from an accumulation of ROS has a detrimental impact on cellular function, and ROS has been implicated in the pathogenesis of a number of diseases, including cardiovascular diseases. This review provides a summary of the impact of ROS on cardiovascular health and diseases, highlighting the therapeutic use of antioxidants. In addition, this review summarizes the health benefits of polyphenols, and the recent progress on understanding the cellular and physiological actions by which polyphenols may impart their beneficial properties on cardiovascular health.

Exercise training prevents oxidative stress and ubiquitin-proteasome system overactivity and reverse skeletal muscle atrophy in heart failure

Background

Heart failure (HF) is known to lead to skeletal muscle atrophy and dysfunction. However, intracellular mechanisms underlying HF-induced myopathy are not fully understood. We hypothesized that HF would increase oxidative stress and ubiquitin-proteasome system (UPS) activation in skeletal muscle of sympathetic hyperactivity mouse model. We also tested the hypothesis that aerobic exercise training (AET) would reestablish UPS activation in mice and human HF.

Methods/Principal Findings

Time-course evaluation of plantaris muscle cross-sectional area, lipid hydroperoxidation, protein carbonylation and chymotrypsin-like proteasome activity was performed in a mouse model of sympathetic hyperactivity-induced HF. At the 7^th month of age, HF mice displayed skeletal muscle atrophy, increased oxidative stress and UPS overactivation. Moderate-intensity AET restored lipid hydroperoxides and carbonylated protein levels paralleled by reduced E3 ligases mRNA levels, and reestablished chymotrypsin-like proteasome activity and plantaris trophicity. In human HF (patients randomized to sedentary or moderate-intensity AET protocol), skeletal muscle chymotrypsin-like proteasome activity was also increased and AET restored it to healthy control subjects’ levels.

Conclusions

Collectively, our data provide evidence that AET effectively counteracts redox imbalance and UPS overactivation, preventing skeletal myopathy and exercise intolerance in sympathetic hyperactivity-induced HF in mice. Of particular interest, AET attenuates skeletal muscle proteasome activity paralleled by improved aerobic capacity in HF patients, which is not achieved by drug treatment itself. Altogether these findings strengthen the clinical relevance of AET in the treatment of HF.

Eryptosis and oxidative damage in type 2 diabetic mellitus patients with chronic kidney disease

It has been suggested that oxidative stress may participate in the progression of diabetes and its complications. Long-term complications of type 2 diabetes mellitus (T2DM) include retinopathy, atherosclerosis, shortened life span of erythrocytes, nephropathy, and chronic kidney disease (CKD). Oxidative damage has been associated with erythrocyte apoptosis induction in other pathological conditions. Our aim was to study the presence of eryptosis and its possible relationship with oxidative damage in patients with T2DM without CKD (T2DM/CKD(-)) and in patients with T2DM and CKD (T2DM/CKD(+)).Oxidative damage of lipids erythrocytes were increased in diabetic patients. The highest lipoperoxidation was found in T2DM/CKD(+). Likewise, the lower plasma total antioxidant capacity, GSH/GSSG ratio, and GSH in erythrocytes were found in T2DM/CKD(+) patients. A negative correlation was found between plasma total antioxidant capacity and oxidative damage. Phosphatidylserine (PS) externalization was measured in erythrocytes to evaluate eryptosis. Annexin binding in erythrocytes of T2DM/CKD(+) patients was higher than in healthy subjects and T2DM/CKD(-) patients. A positive correlation between lipoperoxidation and PS externalization in erythrocytes was found. This work showed that the erythrocytes of diabetic patients have increased oxidative damage, a reduction of antioxidant systems and more erythrocyte PS externalization. The duration of diabetes and the presence of CKD increase both oxidative damage and eryptosis. It is possible that a longer time of evolution induces an increase in erythrocyte oxidative damage and the consumption of blood antioxidant systems, adding to the osmotic stress in CKD and so contributes to an increase in PS externalization in diabetic patients.