Interaction of miR-146a-5p with oxidative stress and inflammation in complications of type 2 diabetes mellitus in male rats: Anti-oxidant and anti-inflammatory protection strategies in type 2 diabetic retinopathy

The Interplay Between Cytokines and MicroRNAs to Regulate Metabolic Disorders

Metabolic disorders represent significant public health challenges worldwide. Emerging evidence suggests that cytokines and microRNAs (miRNAs) play crucial roles in the pathogenesis of metabolic disorders by regulating various metabolic processes, including insulin sensitivity, lipid metabolism, and inflammation. This review provides a comprehensive overview of the intricate interplay between cytokines and miRNAs in the context of metabolic disorders, including obesity, type 2 diabetes, and cardiovascular diseases. We discuss how dysregulation of cytokine-miRNA networks contributes to the development and progression of metabolic disorders and explore the therapeutic potential of targeting these interactions for disease management.

Renoprotective effect of a novel combination of 6-gingerol and metformin in high-fat diet/streptozotocin-induced diabetic nephropathy in rats via targeting miRNA-146a, miRNA-223, TLR4/TRAF6/NLRP3 inflammasome pathway and HIF-1α

BACKGROUND

MiRNA-146a and miRNA-223 are key epigenetic regulators of toll-like receptor 4 (TLR4)/tumor necrosis factor-receptor-associated factor 6 (TRAF6)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome pathway, which is involved in diabetic nephropathy (DN) pathogenesis. The currently available oral anti-diabetic treatments have been insufficient to halt DN development and progression. Therefore, this work aimed to assess the renoprotective effect of the natural compound 6-gingerol (GR) either alone or in combination with metformin (MET) in high-fat diet/streptozotocin-induced DN in rats. The proposed molecular mechanisms were also investigated.

METHODS

Oral gavage of 6-gingerol (100 mg/kg) and metformin (300 mg/kg) were administered to rats daily for eight weeks. MiRNA-146a, miRNA-223, TLR4, TRAF6, nuclear factor-kappa B (NF-κB) (p65), NLRP3, caspase-1, and hypoxia-inducible factor-1 alpha (HIF-1α) mRNA expressions were measured using real-time PCR. ELISA was used to measure TLR4, TRAF6, NLRP3, caspase-1, tumor necrosis factor-alpha (TNF-α), and interleukin-1-beta (IL-1β) renal tissue levels. Renal tissue histopathology and immunohistochemical examination of fibronectin and NF-κB (p65) were performed.

RESULTS

6-Gingerol treatment significantly reduced kidney tissue damage and fibrosis. 6-Gingerol up-regulated miRNA-146a and miRNA-223 and reduced TLR4, TRAF6, NF-κB (p65), NLRP3, caspase-1, TNF-α, IL-1β, HIF-1α and fibronectin renal expressions. 6-Gingerol improved lipid profile and renal functions, attenuated renal hypertrophy, increased reduced glutathione, and decreased blood glucose and malondialdehyde levels. 6-Gingerol and metformin combination showed superior renoprotective effects than either alone.

CONCLUSION

6-Gingerol demonstrated a key protective role in DN by induction of miRNA-146a and miRNA-223 expression and inhibition of TLR4/TRAF6/NLRP3 inflammasome signaling. 6-Gingerol, a safe, affordable, and abundant natural compound, holds promise for use as an adjuvant therapy with metformin in diabetic patients to attenuate renal damage and stop the progression of DN.

Advances in Research Related to MicroRNA for Diabetic Retinopathy

Diabetic retinopathy (DR) is a severe microvascular complication of diabetes and is one of the primary causes of blindness in the working-age population in Europe and the United States. At present, no cure is available for DR, but early detection and timely intervention can prevent the rapid progression of the disease. Several treatments for DR are known, primarily ophthalmic treatment based on glycemia, blood pressure, and lipid control, which includes laser photocoagulation, glucocorticoids, vitrectomy, and antivascular endothelial growth factor (anti-VEGF) medications. Despite the clinical efficacy of the aforementioned therapies, none of them can entirely shorten the clinical course of DR or reverse retinopathy. MicroRNAs (miRNAs) are vital regulators of gene expression and participate in cell growth, differentiation, development, and apoptosis. MicroRNAs have been shown to play a significant role in DR, particularly in the molecular mechanisms of inflammation, oxidative stress, and neurodegeneration. The aim of this review is to systematically summarize the signaling pathways and molecular mechanisms of miRNAs involved in the occurrence and development of DR, mainly from the pathogenesis of oxidative stress, inflammation, and neovascularization. Meanwhile, this article also discusses the research progress and application of miRNA-specific therapies for DR.

Injection of resistin into the paraventricular nucleus produces a cardiovascular response that may be mediated by glutamatergic transmission in the rostral ventrolateral medulla

Objectives

High levels of resistin are associated with metabolic diseases and their complications, including hypertension. The paraventricular nucleus (PVN) is also involved in metabolic disorders and cardiovascular diseases, such as hypertension. Therefore, this study aimed to study cardiovascular (CV) responses evoked by the injection of resistin into the lateral ventricle (LV) and PVN and determine the mechanism of these responses in the rostral ventrolateral medulla (RVLM).

Materials and Methods

Arterial pressure (AP) and heart rate (HR) were evaluated in urethane-anesthetized male rats (1.4 g/kg intraperitoneally) before and after all injections. This study was carried out in two stages. Resistin was injected into LV at the first stage, and AP and HR were evaluated. After that, the paraventricular, supraoptic, and dorsomedial nuclei of the hypothalamus were chosen to evaluate the gene expression of c-Fos. Afterward, resistin was injected into PVN, and cardiovascular responses were monitored. Then to detect possible neural mechanisms of resistin action, agonists or antagonists of glutamatergic, GABAergic, cholinergic, and aminergic transmissions were injected into RVLM.

Results

Resistin injection into LV or PVN could increase AP and HR compared to the control group and before injection. Resistin injection into LV also increases the activity of RVLM, paraventricular, supraoptic, and dorsomedial areas. Moreover, the CV reflex created by the administration of resistin in PVN is probably mediated by glutamatergic transmission within RVLM.

Conclusion

It can be concluded that hypothalamic nuclei, including paraventricular, are important central areas for resistin actions, and glutamatergic transmission in RVLM may be one of the therapeutic targets for high AP in obese people or with metabolic syndrome.

Evaluation of Expression of Cytochrome P450 Aromatase and Inflammatory, Oxidative, and Apoptotic Markers in Testicular Tissue of Obese Rats (Pre)Treated with Garlic Powder

Today, adolescent obesity is recognized as an epidemic and a cause of reproductive disorders. Decreased testosterone levels occur due to functional defects in the hypothalamus-pituitary axis, excessive activity of cytochrome P450 aromatase enzyme, and testicular dysfunction in these people. Oxidative damage, inflammation, and apoptosis are also the main mechanisms of testicular damage during obesity. The use of herbal products such as garlic can improve this disorder due to its anti-inflammatory and antioxidant properties. Therefore, the aim of this study is to investigate the effect of pretreatment and treatment of garlic powder on the expression of cytochrome P450 aromatase enzyme and the expression of genes involved in testosterone synthesis, inflammation, oxidative damage, apoptosis in testicular tissue, and metabolic function of liver tissue in young male obese rats. Eighty male Wistar rats were divided into the controlled and treated groups. Serum levels of lipid, glucose, and insulin as metabolic factors were measured along with the testicular antioxidant and inflammation markers. The expression of Bcl2, Bax, and caspase-3 along with NF-κB, SREBP-1c, CPT-1beta, Nrf-2, CD36, FAS, CYP19A1, P450scc, StAR, 17βHSD, PPARα, and aromatase (CYP19, P450arom) was also measured. Testicular histological evaluation and spermatogenic process was also performed. The results showed that oxidative, inflammatory, and metabolic factors significantly increased in obese rats. The testicular expression of aromatase, NF-κB, Bax, and caspase 3 increased and Nrf2 expression decreased in obese rats, while (pre) treatment with garlic powder significantly decreased the expression of these genes in obese rats. These results were also confirmed by the findings of the histological evaluation and sperm analysis. It can be concluded that garlic powder could improve reproductive dysfunction in obese rats.

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.