Melatonin ameliorates myocardial infarction in obese diabetic individuals: The possible involvement of macrophage apoptotic factors

Melatonin modulates mitochondrial function and inhibits atherosclerosis progression through NRF2 activation and OPA1 inhibition

BACKGROUND

Atherosclerosis (AS), a major cardiovascular disease, is characterized by chronic inflammation and oxidative stress. Melatonin (MLT) has emerged as a potential therapeutic agent due to its anti-inflammatory and antioxidant properties, although the specific mechanisms underlying its action, especially as far as mitochondrial function in AS is concerned, have yet to be fully elucidated.

METHODS

In this study, ApoE-/- mice were fed a high-fat diet with or without MLT treatment. Aortic tissues were analyzed using hematoxylin and eosin, Masson staining, qPCR, and immunofluorescence. Oxidized low-density lipoprotein-treated RAW264.7 macrophages were assessed for AS progression, mitochondrial function, and oxidative stress using electron microscopy, Seahorse analysis, and molecular docking.

RESULTS

MLT treatment significantly reduced atherosclerotic plaque formation, systemic and mitochondrial oxidative stress, and inflammation. MLT treatment was found to enhance mitochondrial function through upregulating the expression of key regulators of mitochondrial biogenesis and the activity of mitochondrial respiratory chain complexes, whereas markers of mitochondrial fusion [for example, optic atrophy protein 1 (OPA1)] were downregulated. Mechanistically, MLT was shown to directly interact with nuclear factor erythroid 2-related factor 2 (NRF2), thereby activating its antioxidant pathway, which in turn regulated mitochondrial function. Additionally, OPA1 was identified as a downstream target of MLT, and its inhibition improved mitochondrial function and reduced inflammation.

CONCLUSION

This study is the first to elucidate that MLT synergistically ameliorates mitochondrial dysfunction through dual mechanisms-activating the NRF2 antioxidant pathway and suppressing OPA1-mediated mitochondrial fusion-providing novel therapeutic targets for AS.

Cardiosplenic axis-targeted immunomodulatory liposome for myocardial ischemia-reperfusion injury treatment

Monocyte/macrophage (Mo/Mϕ) infiltration is critical in myocardial ischemia-reperfusion injury (MIRI). However, the complex composition of the myocardium severely hinders drug accumulation and makes it challenging to modulate the Mo/Mϕ immune response at the MIRI site. The spleen, acting as a Mo/Mϕ reservoir, plays a crucial role in the development of MIRI along the cardiosplenic axis. Compared to directly delivering medications to the MIRI site, targeting the spleen for Mo/Mϕ immunomodulation provides an alternative strategy to modulate the immunological phenotype on-site. Therefore, we developed a melatonin-loaded liposome (ST-MT@lipo2) that specifically targets the spleen and can effectively regulate the immunological response of splenic monocytes and macrophages, consequently enhancing their immune response at the site of MIRI. Additionally, the splenectomy mouse model revealed that ST-MT@lipo2 regulated MIRI's immune response through the cardiosplenic axis by regulating the MCP-1/CCR2 pathway to reduce circulating inflammatory monocyte migration from the spleen to the MIRI site. Moreover, pathological staining and echocardiography showed that ST-MT@lipo2 reduced myocardial damage and improved cardiac function in MIRI mice. This study demonstrates the crucial importance of modulating the immune response in the cardiosplenic axis for treating MIRI, which also inspired the treatments for inflammatory diseases by controlling the spleen immunological milieu.

Melatonin Alleviates Oxidative Stress-Induced Mitochondrial Dysfunction Through Ameliorating NAD+ Homeostasis of hDPSCs for Cell-Based Therapy

Human dental pulp stem cells (hDPSCs) exhibit amazing therapeutic abilities in a variety of diseases due to their remarkable self-renewal capacity and multi-differentiation potential. However, their therapeutic potential could be weakened by various factors such as oxidative stress in cell survival microenvironment In Vivo. Here, we explored the protective effect and mechanism of melatonin (Mel) on hDPSCs transplanted in a type 1 diabetes mellitus (T1DM) rat model. Nicotinamide adenine dinucleotide (NAD+) metabolism and mitochondrial function were remarkably impaired in T1DM rats caused by oxidative stress, while the combination of Mel and post-hDPSCs transplantation could rebalance NAD+ homeostasis through regulating NAMPT-NAD+-SIRT1 axis. Furthermore, Mel significantly reduced intracellular and mitochondrial reactive oxygen species, and alleviated cell senescence and apoptosis of hDPSCs exposed to hydrogen peroxide through ameliorating NAD+ depletion and mitochondrial dysfunction. The protective role of Mel could be extremely essential to stem cells in tissue engineering and regenerative medicine.

Melatonin as an adjunctive therapy in cardiovascular disease management

Melatonin, N-acetyl-5-methoxytryptamine, is a neuroendocrine hormone secreted by the pineal gland. This pleiotropic indoleamine possesses amphiphilic properties, allowing it to penetrate most biological barriers and exert its effects at the subcellular level. Importantly, melatonin also plays a crucial role in regulating the body's response to circadian rhythms, adapting to internal and external environmental cues. Melatonin functions as a powerful antioxidant and free radical scavenger, protecting cells from oxidative damage. Its diverse physiological roles include maintaining the functional integrity of endothelial cells, thereby preventing atherosclerosis, a major contributor to cardiovascular disease. Additionally, melatonin exhibits antioxidant and free radical scavenging properties, potentially improving metabolic disorders. These combined effects suggest a unique adjunctive therapeutic potential for melatonin in treating cardiovascular diseases. This review aims to explore the mechanisms by which melatonin interacts with the cardiovascular system and investigates its potential use as an adjunctive therapeutic agent in managing cardiovascular disease.

Therapeutic strategies targeting mechanisms of macrophages in diabetic heart disease

Diabetic heart disease (DHD) is a serious complication in patients with diabetes. Despite numerous studies on the pathogenic mechanisms and therapeutic targets of DHD, effective means of prevention and treatment are still lacking. The pathogenic mechanisms of DHD include cardiac inflammation, insulin resistance, myocardial fibrosis, and oxidative stress. Macrophages, the primary cells of the human innate immune system, contribute significantly to these pathological processes, playing an important role in human disease and health. Therefore, drugs targeting macrophages hold great promise for the treatment of DHD. In this review, we examine how macrophages contribute to the development of DHD and which drugs could potentially be used to target macrophages in the treatment of DHD.

The Dual Angiogenesis Effects via Nrf2/HO-1 Signaling Pathway of Melatonin Nanocomposite Scaffold on Promoting Diabetic Bone Defect Repair

Purpose

Given the escalating prevalence of diabetes, the demand for specific bone graft materials is increasing, owing to the greater tendency towards bone defects and more difficult defect repair resulting from diabetic bone disease (DBD). Melatonin (MT), which is known for its potent antioxidant properties, has been shown to stimulate both osteogenesis and angiogenesis.

Methods

MT was formulated into MT@PLGA nanoparticles (NPs), mixed with sodium alginate (SA) hydrogel, and contained within a 3D printing polycaprolactone/β-Tricalcium phosphate (PCL/β-TCP) scaffold. The osteogenic capacity of the MT nanocomposite scaffold under diabetic conditions was demonstrated via in vitro and in vivo studies and the underlying mechanisms were investigated.

Results

Physicochemical characterization experiments confirmed the successful fabrication of the MT nanocomposite scaffold, which can achieve long-lasting sustained release of MT. The in vitro and in vivo studies demonstrated that the MT nanocomposite scaffold exhibited enhanced osteogenic capacity, which was elucidated by the dual angiogenesis effects activated through the NF-E2-related factor 2/Heme oxygenase 1 (Nrf2/HO-1) signaling pathway, including the enhancement of antioxidant enzyme activity to reduce the oxidative stress damage of vascular endothelial cells (VECs) and directly stimulating vascular endothelial growth factor (VEGF) production, which reversed the angiogenesis-osteogenesis uncoupling and promoted osteogenesis under diabetic conditions.

Conclusion

This study demonstrated the research prospective and clinical implications of the MT nanocomposite scaffold as a novel bone graft for treating bone defect and enhancing bone fusion in diabetic individuals.

New Perspectives on the Role and Therapeutic Potential of Melatonin in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death and disability worldwide. It is essential to develop novel interventions to prevent/delay CVDs by targeting their fundamental cellular and molecular processes. Melatonin is a small indole molecule acting both as a hormone of the pineal gland and as a local regulator molecule in various tissues. It has multiple features that may contribute to its cardiovascular protection. Moreover, melatonin enters all cells and subcellular compartments and crosses morphophysiological barriers. Additionally, this indoleamine also serves as a safe exogenous therapeutic agent. Increasing evidence has demonstrated the beneficial effects of melatonin in preventing and improving cardiovascular risk factors. Exogenous administration of melatonin, as a result of its antioxidant and anti-inflammatory properties, has been reported to decrease blood pressure, protect against atherosclerosis, attenuate molecular and cellular damage resulting from cardiac ischemia/reperfusion, and improve the prognosis of myocardial infarction and heart failure. This review aims to summarize the beneficial effects of melatonin against these conditions, the possible protective mechanisms of melatonin, and its potential clinical applicability in CVDs.

Melatonin protects against myocardial ischemia-reperfusion injury by inhibiting excessive mitophagy through the Apelin/SIRT3 signaling axis

Excessive or uncontrolled mitophagy may result in a drastic shortage of healthy mitochondrial for ATP supply after reperfusion, leading to irreversible myocardial damage. Melatonin, a hormone produced by the pineal gland, has been proven to ameliorate myocardial ischemia-reperfusion (I/R) injury via regulating mitophagy. However, its underlying mechanism has not been fully elucidated. The present study focused on the role of mitophagy in the cardioprotective effects of melatonin by using the myocardial I/R rat model. The rats were pretreated with or without the apelin inhibitor ML221, the sirtuin 3 (SIRT3) inhibitor 3-TYP and then subjected to I/R injury, with melatonin administrated 10 min before reperfusion. The effects of melatonin on myocardial infarct size, biomarkers of myocardial injury, oxidative stress, and mitochondrial function were detected, and the expression of apelin, SIRT3, and mitophagy-related proteins were also measured. Excessive mitophagy was activated after I/R injury and was correlated with oxidative stress and mitochondrial dysfunction. Melatonin pretreatment ameliorated myocardial injury by decreasing oxidative stress, restoring mitochondrial function, and inhibiting excessive mitophagy. However, ML221 or 3-TYP disrupted these beneficial effects of melatonin on I/R injury. Taken together, these results suggest that melatonin pretreatment ameliorates myocardial I/R injury through regulating the apelin/SIRT3 pathway to inhibit excessive mitophagy.

Therapeutic Benefits of Melatonin against COVID-19

The assumption of the pineal hormone melatonin as a therapeutic use for COVID-19-affected people seems promising. Its intake has shown significant improvement in the patients' conditions. Higher melatonin titers in children may provide a protective shield against this disease. The hormone melatonin works as an anti-inflammatory, antioxidant, immunomodulator, and strategically slows down the cytokine release which is observed in the COVID-19 disease, thereby improving the overall health of afflicted patients. The medical community is expected shortly to use remedial attributes like anti-inflammatory, antioxidant, antivirals, etc., of melatonin in the successful prevention and cure of COVID-19 morbidity. Thus, the administration of melatonin seems auspicious in the cure and prevention of this COVID-19 fatality. Moreover, melatonin does not seem to reduce the efficiency of approved vaccines against the SARS-CoV-2 virus. Melatonin increases the production of inflammatory cytokines and Th1 and enhances both humoral and cell-mediated responses. Through the enhanced humoral immunity, melatonin exhibits antiviral activities by suppressing multiple inflammatory products such as IL-6, IL1β, and tumor necrosis factor α, which are immediately released during lung injury of severe COVID-19. Hence, the novel use of melatonin along with other antivirals as an early treatment option against COVID-19 infection is suggested. Here, we have chalked out the invasion mechanisms and appropriate implications of the latest findings concerned with melatonin against the virus SARS-CoV-2. Nevertheless, within the setting of a clinical intervention, the promising compounds must go through a series of studies before their recommendation. In the clinical field, this is done in a time-ordered sequence, in line with the phase label affixed to proper protocol of trials: phase I-phase II and the final phase III. Nevertheless, while medical recommendations can only be made on the basis of reassuring evidence, there are still three issues worth considering before implementation: representativeness, validity, and lastly generalizability.