Melatonin Enhances Autophagy and Decreases Apoptosis Induced by nanosilica in RAW264.7 cells

Melatonin suppresses atherosclerosis by ferroptosis inhibition via activating NRF2 pathway

Melatonin (MLT), a conserved small indole compound, exhibits anti-inflammatory and antioxidant properties, contributing to its cardioprotective effects. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with atherosclerosis disease risk, and is known as an atherosclerosis risk biomarker. This study aimed to investigate the impact of MLT on Lp-PLA2 expression in the atherosclerotic process and explore the underlying mechanisms involved. In vivo, ApoE-/- mice were fed a high-fat diet, with or without MLT administration, after which the plaque area and collagen content were assessed. Macrophages were pretreated with MLT combined with ox-LDL, and the levels of ferroptosis-related proteins, NRF2 activation, mitochondrial function, and oxidative stress were measured. MLT administration significantly attenuated atherosclerotic plaque progression, as evidenced by decreased plaque area and increased collagen. Compared with those in the high-fat diet (HD) group, the levels of glutathione peroxidase 4 (GPX4) and SLC7A11 (xCT, a cystine/glutamate transporter) in atherosclerotic root macrophages were significantly increased in the MLT group. In vitro, MLT activated the nuclear factor-E2-related Factor 2 (NRF2)/SLC7A11/GPX4 signaling pathway, enhancing antioxidant capacity while reducing lipid peroxidation and suppressing Lp-PLA2 expression in macrophages. Moreover, MLT reversed ox-LDL-induced ferroptosis, through the use of ferrostatin-1 (a ferroptosis inhibitor) and/or erastin (a ferroptosis activator). Furthermore, the protective effects of MLT on Lp-PLA2 expression, antioxidant capacity, lipid peroxidation, and ferroptosis were decreased in ML385 (a specific NRF2 inhibitor)-treated macrophages and in AAV-sh-NRF2 treated ApoE-/- mice. MLT suppresses Lp-PLA2 expression and atherosclerosis processes by inhibiting macrophage ferroptosis and partially activating the NRF2 pathway.

The signal pathway of melatonin mediates the monochromatic light-induced T-lymphocyte apoptosis in chicken thymus

Our previous study revealed that under monochromatic red light (RL), the melatonin nuclear receptor reduces the proliferation activity of broiler thymic lymphocytes through the P65 signaling pathway. The main objective of this study was to investigate the signal mechanism by which RL decreases thymic lymphocyte proliferation. Initially, broilers were purchased and randomly assigned to be fed under white light (WL), red light (RL), green light (GL), and blue light (BL). Pinealectomy was performed 3 d later, and the broilers were euthanized after 14 d. The results showed that the expression of the antiapoptotic proteins Bcl-2/Bcl-xl decreased under RL, while the expression of the pro-apoptotic factor Bax/caspase-3 and the pro-inflammatory factors INF-γ/TNF-α/IL-6 increased. After pinealectomy, the expression of Bax/TNF-α/IL-6 increased in conjunction with the decrease in Bcl-2 expression. In vitro experiments demonstrated that exogenous melatonin decreased the expression of Bax/TNF-α/IL-6 in thymic lymphocytes of chicks reared under RL. This melatonin-induced effect was enhanced by SR1078 (RORα/RORγ agonist) but attenuated by SR3335 (RORα antagonist) and BAY (P65 antagonist). These findings revealed that the melatonin nuclear receptor RORα/RORγ promotes the expression of the pro-apoptotic factor Bax/caspase-3 and the pro-inflammatory factors INF-γ/TNF-α/IL-6, while inhibiting the expression of the antiapoptotic factor Bcl-2/Bcl-xl. Our research suggested the signaling pathway of monochromatic red light impacts the apoptosis of thymus lymphocytes in broiler.

Melatonin Derivative-Conjugated Formulations of Pd(II) and Pt(II) Thiazoline Complexes on Mesoporous Silica to Enhance Cytotoxicity and Apoptosis against HeLa Cells

The search for alternatives to cisplatin has led to the development of new metal complexes where thiazoline derivatives based on platinum(II) and palladium(II) stand out. In this sense, the Pt(II) and Pd(II) complexes coordinated with the thiazoline derivative ligand 2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine (TdTn), with formula [PtCl2(TdTn)] and [PdCl2(TdTn)], have previously shown good results against several cancer lines; however, in this work, we have managed to improve their activity by supporting them on mesoporous silica nanoparticles (MSN). The incorporation of metal compounds with a melatonin derivative (5-methoxytryptamine, 5MT), which is a well-known antioxidant and apoptosis inducer in different types of cancer, has been able to increase the cytotoxic activity of both MSN-supported and isolated complexes with only a very low amount (0.35% w/w) of this antioxidant. The covalently functionalized systems that have been synthesized are able to increase selectivity as well as accumulation in HeLa cells. The final materials containing the metal complexes and 5MT (MSN-5MT-PtTdTn and MSN-5MT-PdTdTn) required up to nine times less metal to achieve the same cytotoxic activity than their corresponding non-formulated counterparts did, thus reducing the potential side effects caused by the use of the free metal complexes.

Effects of dietary melatonin on antioxidant and immune function of the Pacific white shrimp (Litopenaeus vannamei), as determined by transcriptomic analysis

Melatonin (MT) is regarded as an antioxidant and immunostimulant that can efficiently scavenge free radicals and activate antioxidant enzymes. The aim of this study was to investigate the effects of dietary MT on the growth performance and immune function of the Pacific white shrimp (Litopenaeus vannamei). Six groups of L. vannamei were supplemented with dietary MT at 0, 22.5, 41.2, 82.7, 165.1, and 329.2 mg/kg levels for 2 months. RNA-Seq analysis was performed to obtain transcriptome data of the control group and the group supplemented with dietary MT at 82.7 mg/kg BW. In total, 1220 DEGs (799 up-regulated and 421 down-regulated) were identified. Pathways and genes related to growth performance and immune function were verified by real-time quantitative polymerase chain reaction. The total hemocyte count, phagocytosis rate, and respiratory burst were significantly increased in the MT (82.7 mg/kg BW) group as compared to the control group. Analysis of antioxidant-related enzymes in the hepatopancreas showed that dietary MT (82.7 mg/kg BW) significantly increased activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase, while dietary MT at 41.2 mg/kg BW significantly increased activities of glutathione S-transferase, lysozyme (LZM), and phenoloxidase (PO). At the transcriptional level, dietary MT up-regulated expression levels of genes associated with antioxidant immunity and growth, which included PO, SOD, LZM, GPx, chitin synthase, ecdysone receptor, calcium-calmodulin dependent protein kinase I, and retinoid X receptor. In conclusion, dietary MT may improve the growth performance and immune function of L. vannamei to some extent.

Melatonin Exerts Cardioprotective Effects by Inhibiting NLRP3 Inflammasome-Induced Pyroptosis in Mice following Myocardial Infarction

Myocardial infarction- (MI-) induced myocardial damage is mainly attributed to the loss of cardiomyocytes. Pyroptosis is a newly recognized form of programmed cell necrosis that is associated with the progression of MI. Melatonin has been shown to exert cardioprotective effects against cardiac damage in multiple cardiovascular diseases. However, the effect of melatonin on pyroptosis-induced cardiac injury in MI has not been elucidated. Herein, we found that melatonin administration ameliorated cardiac dysfunction and reduced cardiomyocyte death both in mice following coronary artery ligation and in H9C2 cells exposed to hypoxia. The results also showed that pyroptosis was induced both in vivo and in vitro, as evidenced by increased NLRP3, cleaved caspase-1, GSDMD-N, and mature IL-1β and IL-18 levels, and these changes were decreased by melatonin treatment. Furthermore, we observed that TLR4 and NF-κB levels were increased by MI or hypoxia, and these increases were reversed by melatonin. The antipyroptotic action of melatonin was abrogated by treatment with an agonist of the TLR4/NF-κB signaling pathway. Our results indicate that melatonin can exert cardioprotective effects by inhibiting NLRP3 inflammasome-induced pyroptosis through modulation of the TLR4/NF-κB signaling pathway and provide strong evidence for the utility of melatonin in the treatment of MI.

The Melatonin and Enriched Environment Ameliorated Low Protein-Induced Intrauterine Growth Retardation by IGF-1 And mtor Signaling Pathway and Autophagy Inhibition in Rats

CDATA[Aim: The present study investigated whether melatonin (MEL) and enriched environment (EE) might protect against intrauterine growth retardation (IUGR) in rats.

METHODS

Sprague-Dawley rats were randomly allocated to 3 groups: control (C), model (M) and EE+MEL group. Animals were housed in an enriched environment (EE+MEL group) or remained in a standard environment (C group, M group). IUGR rat model was built by feeding a low protein diet during pregnancy. MEL was administered by gavaging. At day 1 post-birth, the baseline characteristics and serum biochemical parameters, morphology of liver and small intestine, enzyme activities, and mRNA expression levels of fetal rats were determined. The autophagy marker LC3 and Beclin1 were determined by western blot analysis.

RESULTS

EE+MEL markedly improved the baseline characteristics, hepatic and intestinal morphology of IUGR fetuses. In addition, the lactase activities in the fetal intestine were markedly increased by the EE+MEL. The levels of serum somatostatin (SST), Growth hormone (GH), GH releasing hormone (GHRH), Insulin-like Growth Factor 1 (IGF-1), triiodothyronine (T3), and tetraiodothyronine (T4) were found to be recovered by EE+MEL. In addition, the EE+MEL significantly ameliorated the mRNA expression of SST, GHRH, and GHRH receptor (GHRHR), GH, GHR, IGF-1, and IGF-1 receptor (IGF1R), IGF binding protein-1 (IGFBP1), mammalian target of rapamycin (mTOR), S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E (eIF4E)-binding protein 1 (4EBP1) in fetuses. In IUGR fetal livers, LC3 and Beclin1 were found to be increased at birth, while LC3 and Beclin1 were observed to be significantly decreased in the EE+MEL group.

CONCLUSION

EE+MEL could improve fetal rats' baseline characteristics, serum biochemical parameters, birth weight, intestinal and hepatic morphology and enzyme activities. These effects could be explained by the activation of the IGF-1/IGFBP1 and IGF-1/mTOR/S6K1/4EBP1 signaling pathway and autophagy inhibition.

Melatonin prevents neuroinflammation and relieves depression by attenuating autophagy impairment through FOXO3a regulation

Major depressive disorder (MDD) is a life-threatening illness characterized by mood changes and high rates of suicide. Although the role of neuroinflammation in MMD has been studied, the mechanistic interplay between antidepressants, neuroinflammation, and autophagy is yet to be investigated. The present study investigated the effect of melatonin on LPS-induced neuroinflammation, depression, and autophagy impairment. Our results showed that in mice, lipopolysaccharide (LPS) treatment induced depressive-like behaviors and caused autophagy impairment by dysregulating ATG genes. Moreover, LPS treatment significantly increased the levels of cytokines (TNFα, IL-1β, IL-6), enhanced NF-ᴋB phosphorylation, caused glial (astrocytes and microglia) cell activation, dysregulated FOXO3a expression, increased the levels of redox signaling molecules such as ROS/TBARs, and altered expression of Nrf2, SOD2, and HO-1. Melatonin treatment significantly abolished the effects of LPS, as demonstrated by improved depressive-like behaviors, normalized autophagy-related gene expression, and reduced levels of cytokines. Further, we investigated the role of autophagy in LPS-induced depressive-like behavior and neuroinflammation using autophagy inhibitors 3-MA and Ly294002. Interestingly, inhibitor treatment significantly abolished and reversed the anti-depressive, pro-autophagy, and anti-inflammatory effects of melatonin. The present study concludes that the anti-depressive effects of melatonin in LPS-induced depression might be mediated via autophagy modulation through FOXO3a signaling.

A Comprehensive Review of Autophagy and Its Various Roles in Infectious, Non-Infectious, and Lifestyle Diseases: Current Knowledge and Prospects for Disease Prevention, Novel Drug Design, and Therapy

Autophagy (self-eating) is a conserved cellular degradation process that plays important roles in maintaining homeostasis and preventing nutritional, metabolic, and infection-mediated stresses. Autophagy dysfunction can have various pathological consequences, including tumor progression, pathogen hyper-virulence, and neurodegeneration. This review describes the mechanisms of autophagy and its associations with other cell death mechanisms, including apoptosis, necrosis, necroptosis, and autosis. Autophagy has both positive and negative roles in infection, cancer, neural development, metabolism, cardiovascular health, immunity, and iron homeostasis. Genetic defects in autophagy can have pathological consequences, such as static childhood encephalopathy with neurodegeneration in adulthood, Crohn's disease, hereditary spastic paraparesis, Danon disease, X-linked myopathy with excessive autophagy, and sporadic inclusion body myositis. Further studies on the process of autophagy in different microbial infections could help to design and develop novel therapeutic strategies against important pathogenic microbes. This review on the progress and prospects of autophagy research describes various activators and suppressors, which could be used to design novel intervention strategies against numerous diseases and develop therapeutic drugs to protect human and animal health.