Modulation of hippocampal gene expression of microRNA-146a/microRNA-155-nuclear factor-kappa B inflammatory signaling by troxerutin in healthy and diabetic rats

Role of MicroRNA in linking diabetic retinal neurodegeneration and vascular degeneration

Diabetic retinopathy is the major cause of blindness in diabetic patients, with limited treatment options that do not always restore optimal vision. Retinal nerve degeneration and vascular degeneration are two primary pathological processes of diabetic retinopathy. The retinal nervous system and vascular cells have a close coupling relationship. The connection between neurodegeneration and vascular degeneration is not yet fully understood. Recent studies have found that microRNA plays a role in regulating diabetic retinal neurovascular degeneration and can help delay the progression of the disease. This article will review how microRNA acts as a bridge connecting diabetic retinal neurodegeneration and vascular degeneration, focusing on the mechanisms of apoptosis, oxidative stress, inflammation, and endothelial factors. The aim is to identify valuable targets for new research and clinical treatment of diabetic retinopathy.

Flavonols as a Potential Pharmacological Intervention for Alleviating Cognitive Decline in Diabetes: Evidence from Preclinical Studies

Diabetes mellitus is a complex metabolic disease associated with reduced synaptic plasticity, atrophy of the hippocampus, and cognitive decline. Cognitive impairment results from several pathological mechanisms, including increased levels of advanced glycation end products (AGEs) and their receptors, prolonged oxidative stress and impaired activity of endogenous mechanisms of antioxidant defense, neuroinflammation driven by the nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), decreased expression of brain-derived neurotrophic factor (BDNF), and disturbance of signaling pathways involved in neuronal survival and cognitive functioning. There is increasing evidence that dietary interventions can reduce the risk of various diabetic complications. In this context, flavonols, a highly abundant class of flavonoids in the human diet, are appreciated as a potential pharmacological intervention against cognitive decline in diabetes. In preclinical studies, flavonols have shown neuroprotective, antioxidative, anti-inflammatory, and memory-enhancing properties based on their ability to regulate glucose levels, attenuate oxidative stress and inflammation, promote the expression of neurotrophic factors, and regulate signaling pathways. The present review gives an overview of the molecular mechanisms involved in diabetes-induced cognitive dysfunctions and the results of preclinical studies showing that flavonols have the ability to alleviate cognitive impairment. Although the results from animal studies are promising, clinical and epidemiological studies are still needed to advance our knowledge on the potential of flavonols to improve cognitive decline in diabetic patients.

Association of MicroRNA-146a with Type 1 and 2 Diabetes and their Related Complications

Most medical investigations have found a reduced blood level of miR-146a in type 2 diabetes (T2D) patients, suggesting an important role for miR-146a (microRNA-146a) in the etiology of diabetes mellitus (DM) and its consequences. Furthermore, injection of miR-146a mimic has been confirmed to alleviate diabetes mellitus in diabetic animal models. In this line, deregulation of miR-146a expression has been linked to the progression of nephropathy, neuropathy, wound healing, olfactory dysfunction, cardiovascular disorders, and retinopathy in diabetic patients. In this review, besides a comprehensive review of the function of miR-146a in DM, we discussed new findings on type 1 (T1MD) and type 2 (T2DM) diabetes mellitus, highlighting the discrepancies between clinical and preclinical investigations and elucidating the biological pathways regulated through miR-146a in DM-affected tissues.

Biological and Therapeutic Effects of Troxerutin: Molecular Signaling Pathways Come into View

Flavonoids consist a wide range of naturally occurring compounds which are exclusively found in different fruits and vegetables. These medicinal herbs have a number of favourable biological and therapeutic activities such as antioxidant, neuroprotective, renoprotective, anti-inflammatory, anti-diabetic and anti-tumor. Troxerutin, also known as vitamin P4, is a naturally occurring flavonoid which is isolated from tea, coffee and cereal grains as well as vegetables. It has a variety of valuable pharmacological and therapeutic activities including antioxidant, anti-inflammatory, anti-diabetic and anti-tumor. These pharmacological impacts have been demonstrated in in vitro and in vivo studies. Also, clinical trials have revealed the efficacy of troxerutin for management of phlebocholosis and hemorrhoidal diseases. In the present review, we focus on the therapeutic effects and biological activities of troxerutin as well as its molecular signaling pathways.

Ficus pumila L. improves the prognosis of patients infected with HTLV-1, an RNA virus

Human T-cell leukemia virus type 1 was isolated as the retrovirus to be identified in humans. Here, we focused on Ficus pumila L. as a factor that be effective against human T-cell leukemia virus type 1. The significant and novel findings is that symptoms of patients with drinking Ficus pumila L. extracts did not worsen despite a lack of aggressive pharmacotherapy against adult T-cell leukemia, a human T-cell leukemia virus type 1-associated myelopathy, or T-cell leukemia virus type 1 uveitis. Twenty-eight of the 194 inpatients who underwent showed high levels of human T-cell leukemia virus type 1.

Among human T-cell leukemia virus type 1-infected patients, those who were administered Ficus pumila L. extracts had no human T-cell leukemia virus type 1-related symptoms, while those who were not administered Ficus pumila L. extracts had human T-cell leukemia virus type 1-related diseases and a significantly poorer prognosis. This suggests that the Ficus pumila L. extracts may show some utility against virus infection.

The Protective Roles and Molecular Mechanisms of Troxerutin (Vitamin P4) for the Treatment of Chronic Diseases: A Mechanistic Review

Troxerutin (TRX), a semi-synthetic bioflavonoid derived from rutin, has been reported to exert several pharmacological effects including antioxidant, anti-inflammatory, antihyperlipidemic, and nephroprotective. However, the related molecular details and its mechanisms remain poorly understood. In the present review, we presented evidences from the diversity in vitro and in vivo studies on the therapeutic potential of TRX against neurodegenerative, diabetes, cancer and cardiovascular diseases with the purpose to find molecular pathways related to the treatment efficacy. TRX has a beneficial role in many diseases through multiple mechanisms including, increasing antioxidant enzymes and reducing oxidative damage, decreasing in proapoptotic proteins (APAF-1, BAX, caspases-9 and-3) and increasing the antiapoptotic BCL-2, increasing the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and downregulating the nuclear factor κB (NFκ). TRX also reduces acetylcholinesterase activity and upregulates phosphoinositide 3- kinase/Akt signaling pathway in Alzheimer's disease models. Natural products such as TRX may develop numerous and intracellular pathways at several steps in the treatment of many diseases. Molecular mechanisms of action are revealing novel, possible combinational beneficial approaches to treat multiple pathological conditions.

Pretreatment with vildagliptin boosts ischemic-postconditioning effects on cardioprotection and expression profile of genes regulating autophagy and mitochondrial fission/fusion in diabetic heart with reperfusion injury

The burden of myocardial ischemia/reperfusion (IR) injury is 2-3-folds higher in diabetic patients, so protecting diabetic hearts is clinically important. Here, we investigated the effect of combinational therapy with vildagliptin and ischemic postconditioning (IPostC) on cardioprotection and the expression of genes regulating autophagy and mitochondrial function in diabetic hearts with IR injury. Type 2 diabetes was induced through high-fat diet and streptozotocin protocol in Wistar rats. Vildagliptin was orally administered to diabetic rats 5 weeks before IR injury. Myocardial-IR injury was modeled by ligation of left the coronary artery for 30 min followed by 60-min reperfusion, on a Langendorff-perfusion system. IPostC was applied at early reperfusion as 6 alternative cycles of 10-s reperfusion/ischemia. Creatine-kinase levels were measured spectrometrically, and infarct size was evaluated by TTC staining method. Left ventricles were harvested for assessing the expression levels of autophagy and mitochondrial-related genes using real-time PCR. Induction of diabetes significantly increased creatine-kinase release in comparison to healthy rats, and all treatments significantly reduced the release of enzyme toward control levels (P < 0.05). Only the combination therapy (IPostC + vildagliptin) could significantly reduce the infarct size of diabetic hearts as compared to untreated diabetic-IR group (P < 0.01). The levels of autophagy genes LC3 and p62 were significantly higher in diabetic groups than healthy ones. Induction of IR injury in diabetic hearts enhanced mitochondrial fission (drp-1) and reduced mitochondrial fusion (mfn1 and mfn2) genes. IPostC alone had no significant effect on the gene expression and vildagliptin alone could only affect LC3-II and mfn2 expressions. Nevertheless, administration of combination therapy significantly reduced the expression of both autophagy genes and increased both LC3-II/I and mfn2/1 ratios as compared with diabetic-IR hearts (P < 0.01-0.05). Application of this combination therapy could overcome the diabetes-induced failure of cardioprotection by individual treatments and improve mitochondrial dynamic and autophagy flux.

MicroRNA-146a: A Comprehensive Indicator of Inflammation and Oxidative Stress Status Induced in the Brain of Chronic T2DM Rats

Objective: It was demonstrated that inflammation and oxidative stress induced by hyperglycemia were closely associated with alteration of miR-146a. Here, we investigated the role of miR-146a in mediating inflammation and oxidative stress in the brain of chronic T2DM rats.

Methods: The chronic T2DM (cT2DM) models were induced by intraperitoneal administration of STZ (35 mg/kg) after being fed a high-fat, high-sugar diet for 6 weeks. H&E staining was conducted to observe the morphological impairment of the rat hippocampus. The expressions of inflammatory mediators (COX-2, TNF-α, IL-1β) and antioxidant proteins (Nrf2, HO-1) were measured by western blot. The levels of MDA and SOD were detected by the respective activity assay kit. The levels of p22phox and miR-146a were examined by quantitative real-time PCR (qRT-PCR). The expressions of IRAK1, TRAF6 and NF-κB p65 were measured by western blot and qRT-PCR. Pearson correlation analysis was performed to investigate the correlations between miR-146a and inflammatory mediators as well as oxidative stress indicators.

Results: The expression of miR-146a was negatively correlated with inflammation and oxidative stress status. In the brain tissues of cT2DM rats, it was observed that the expressions of inflammatory mediators (COX-2, TNF-α, IL-1β) and oxidative stress indicators including MDA and p22phox were elevated, which were negatively correlated with the expression of miR-146a. While, the antioxidant proteins (Nrf2, HO-1, SOD) levels decreased in the brain of cT2DM rats, which were positively correlated with the miR-146a level. The expressions of NF-κB p65 and its specific modulators (IRAK1&TRAF6) were elevated in the brain of cT2DM rats, which might be inhibited by miR-146a.

Conclusion: Our results implied that increased inflammation and oxidative stress status were associated with brain impairment in cT2DM rats, which were negatively correlated with miR-146a expression. Thus, miR-146a may serve as a negative comprehensive indicator of inflammation and oxidative stress status in the brain of chronic T2DM rats.

Troxerutin and Cerebroprotein Hydrolysate Injection Protects Neurovascular Units from Oxygen-Glucose Deprivation and Reoxygenation-Induced Injury In Vitro

Cerebral ischemia/reperfusion (I/R) injury involves complex events of cellular and molecular processes. Previous studies suggest that a neurovascular unit (NVU) acts as an intricate network to maintain the neuronal homeostatic microenvironment. The present study established an NVU model for oxygen-glucose deprivation and reoxygenation (OGD/R) damage, trying to target the major components of the NVU using a coculture of rat neurons, astrocytes, and rat brain microvascular endothelial cells (rBMECs) to investigate the therapeutic effects of troxerutin and cerebroprotein hydrolysate injections (TCHis). The study observed that OGD/R downregulated the expressions of GAP-43, Claudin-5, and AQP-4 obviously detected by Western blotting and immunocytochemical analysis, respectively, while TCHi ameliorated the effect of OGD/R significantly. Meanwhile, TCHi alleviated the abnormalities of ultrastructure of neurons and rBMECs induced by OGD/R. Furthermore, both levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α) and cell adhesion molecules (VCAM-1 and ICAM-1) detected by ELISA in NVU supernatant were found elevated significantly through OGD/R, but TCHi ameliorated the trend. In addition, TCHi also mitigated the increase of proapoptotic factors (Bax, p53, and caspase-3) induced by OGD/R in NVU model statistically. All these findings demonstrated that TCHis played a protective role, which was reflected in anti-inflammation, antiapoptosis, and blood–brain barrier maintenance. The results of the study concluded that the NVU is an ideal target and TCHi acts as a neuroprotective agent against cerebral I/R injuries.

Exosomes Derived From Mesenchymal Stromal Cells Pretreated With Advanced Glycation End Product-Bovine Serum Albumin Inhibit Calcification of Vascular Smooth Muscle Cells

Background: The osteogenic differentiation of vascular smooth muscle cell (VSMCs) is important for the development of vascular calcification (VC), particularly in diabetes. Exosomes derived from Mesenchymal Stromal Cells (MSCs) are effective against cardiovascular diseases, yet their role in VC remains unclear. Advanced glycation end products (AGEs) inhibit bone marrow stromal cell osteogenesis by targeting osteogenesis-associated genes. Thus, we investigated the role of exosomes derived from MSCs pretreated with AGEs-BSA in VC and its potential mechanisms. Methods: Primary VSMCs and MSCs were isolated from the aorta and bone marrow of Sprague-Dawley rats, respectively. VSMCs were cultured with AGEs-BSA to induce osteogenic differentiation. Exosomes were harvested from MSCs by ultracentrifugation. MSCs and VSMCs were cocultured in Transwells, and exosomes were added to VSMC culture medium to assess their effects on osteogenic differentiation. Double luciferase reporter assay was applied to confirm that miR-146a directly targets the 3' UTR of the thioredoxin-interacting protein (TXNIP) gene. Results: Pretreatment of VSMCs with AGEs-BSA increased the expression of thioredoxin-interacting protein (TXNIP) by inhibiting that of miR-146a, resulting in enhanced ROS production and VSMC calcification. By contrast, the expression of miR-146a in MSCs was increased by AGEs-BSA treatment. Thus, miR-146a was transferred from AGEs-BSA-pretreated or miR-146a-transfected MSCs to VSMCs via exosomes. After coculture with miR-146a-containing exosomes, the AGEs-BSA-mediated increase in VSMC calcification was diminished, accompanied by decreased TXNIP expression and ROS production. Furthermore, TXNIP overexpression counteracted the anti-calcification effects of MSC-derived miR-146a-containing exosomes. In addition, TXNIP was identified as a target gene of miR-146a, and the results of double luciferase reporter assay confirmed that TXNIP was the direct target gene of miR-146a. Conclusions: Exosomes secreted by MSCs pretreated with AGEs-BSA contained a high level of miR-146a, which was transferred to VSMCs and inhibited AGEs-BSA-induced calcification in a TXNIP-dependent manner. Thus, miR-146a-containing exosomes may be a potential therapeutic target for VC.

Erratum: Modulation of hippocampal gene expression of microRNA-146a/microRNA-155-nuclear factor-kappa B inflammatory signaling by troxerutin in healthy and diabetic rats

[This corrects the article on p. 675 in vol. 48, PMID: 28066106.].