Vitamin D receptor activation protects against myocardial reperfusion injury through inhibition of apoptosis and modulation of autophagy

Unravelling the cardioprotective effects of calcitriol in Sunitinib-induced toxicity: A comprehensive in silico and in vitro study

Sunitinib (SUN), a drug used to treat advanced renal cell carcinoma and other cancers, causes cardiotoxicity. This study aimed to identify a potential drug candidate to counteract SUN-induced cardiotoxicity. We analysed real-world data from adverse event report databases of existing clinically approved drugs to identify potential candidates. Through in silico analyses and in vitro experiments, the mechanisms of action were determined. The study identified calcitriol (CTL), an active form of vitamin D, as a promising candidate against SUN-induced cardiotoxicity. In H9c2 cells, SUN decreased cell viability significantly, whereas CTL mitigated this effect significantly. The SUN-treated group exhibited increased autophagy in H9c2 cells, which was reduced significantly in the CTL group. Bioinformatics analysis using Ingenuity Pathway Analysis revealed the mechanistic target of rapamycin (mTOR) as a common factor between autophagy and CTL. Notably, rapamycin, an mTOR inhibitor, nullified the effects of CTL on cell viability and autophagy. Furthermore, SUN treatment led to significant reductions in cardiomyocyte diameters and increases in their widths, changes that were inhibited by CTL. SUN also induced morphological changes in surviving H9c2 cells, causing them to adopt a rounded shape, whereas CTL improved their morphology to resemble the elongated shape of the control group. In conclusion, the findings of the present study suggest that CTL has the potential to prevent SUN-induced cardiomyocyte damage through autophagy, particularly via mTOR-mediated pathways. The findings indicate that CTL could serve as an effective prophylactic agent against SUN-induced cardiotoxicity, offering a promising avenue for further research and potential clinical applications.

Protective Role of Vitamin D Receptor in Cerebral Ischemia/Reperfusion Injury In Vitro and In Vivo Model

BACKGROUND

Vitamin D receptor (VDR) can prevent myocardial ischemia reperfusion injury (MIRI). Hence, we aimed to illuminate the effect of VDR on cerebral ischemia/reperfusion injury (CIRI).

METHODS

C57BL/6 mice and SK-N-SH cells were utilized to establish CIRI and cellular oxygen deprivation/reoxygenation (OGD/R) models. Mice were injected with 1 μg/kg Calcitriol or 1 μg/kg Paricalcitol (PC) and adenovirus-mediated VDR overexpression or knockdown plasmids. 2,3,5-triphenyl-tetrazolium chloride (TTC) and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays were performed to measure the brain infarct volume and the apoptosis of cerebral cells. SK-N-SH cells were treated with 5 mM N-acetyl-L-cysteine (NAC) and transfected with VDR knockdown plasmid. Flow cytometry and Cell Counting Kit-8 (CCK-8) assays were employed to assess the apoptosis and cell viability. Enzyme-Linked Immunosorbent Assay (ELISA), quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) and Western blot were exploited to quantify the levels of reactive species oxygen (ROS), other oxidative stress-related factors, VDR and apoptosis-related factors.

RESULTS

The level of VDR in mouse cerebral tissue was elevated by CIRI (p < 0.001). CIRI-induced cerebral infarction (p < 0.001) and the apoptosis of cerebral cells (p < 0.001) in mice were mitigated by the activation of VDR. VDR overexpression abrogated while VDR silencing enhanced CIRI-induced infarction, oxidative stress and apoptosis of cerebral cells (p < 0.05). Furthermore, VDR silencing aggravated the oxidative stress and apoptosis in OGD/R-treated SK-N-SH cells (p < 0.05). NAC, a scavenger of oxidative stress, could reverse the effects of VDR silencing on apoptosis and oxidative stress in OGD/R-treated SK-N-SH cells (p < 0.01).

CONCLUSION

VDR alleviates the oxidative stress to protect against CIRI.

Vitamin D as a modulator of molecular pathways involved in CVDs: Evidence from preclinical studies

Vitamin D deficiency (VDD) is a widespread global health issue, affecting nearly a billion individuals worldwide, and mounting evidence links it to an increased risk of cardiovascular diseases like hypertension, atherosclerosis, and heart failure. The discovery of vitamin D receptors and metabolizing enzymes in cardiac and vascular cells, coupled with experimental studies, underscores the complex relationship between vitamin D and cardiovascular health. This review aims to synthesize and critically evaluate the preclinical evidence elucidating the role of vitamin D in cardiovascular health. We examined diverse preclinical in vitro (cardiomyocyte cell line) models and in vivo models, including knockout mice, diet-induced deficiency, and disease-specific animal models (hypertension, hypertrophy and myocardial infarction). These studies reveal that vitamin D modulates vascular tone, and prevents fibrosis and hypertrophy through effects on major signal transduction pathways (NF-kB, Nrf2, PI3K/AKT/mTOR, Calcineurin/NFAT, TGF-β/Smad, AMPK) and influences epigenetic mechanisms governing inflammation, oxidative stress, and pathological remodeling. In vitro studies elucidate vitamin D's capacity to promote cardiomyocyte differentiation and inhibit pathological remodeling. In vivo studies further uncovered detrimental cardiac effects of VDD, while supplementation with vitamin D in cardiovascular disease (CVD) models demonstrated its protective effects by decreasing inflammation, attenuating hypertrophy, reduction in plaque formation, and improving cardiac function. Hence, this comprehensive review emphasizes the critical role of vitamin D in cardiovascular health and its potential as a preventive/therapeutic strategy in CVDs. However, further research is needed to translate these findings into clinical applications as there are discrepancies between preclinical and clinical studies.

Nr1h4 and Thrb ameliorate ER stress and provide protection in the MPTP mouse model of Parkinson's

Elevated ER stress has been linked to the pathogenesis of several disease conditions including neurodegeneration. In this study, we have holistically determined the differential expression of all the nuclear receptors (NRs) in the presence of classical ER stress inducers. Activation of Nr1h4 and Thrb by their cognate ligands (GW4064 and T3) ameliorates the tunicamycin (TM)-induced expression of ER stress genes. A combination of both ligands is effective in mitigating cell death induced by TM. Further exploration of their protective effects in the Parkinson's disease (PD) model shows that they reduce MPP+-induced dissipation of mitochondrial membrane potential and ROS generation in an in vitro PD model in neuronal cells. Furthermore, the generation of an experimental murine PD model reveals that simultaneous treatment of GW4064 and T3 protects mice from ER stress, dopaminergic cell death, and functional deficits in the MPTP mouse model of PD. Thus, activation of Nr1h4 and Thrb by their respective ligands plays an indispensable role in ER stress amelioration and mounts protective effects in the MPTP mouse model of PD.

Associations between vitamin D status, VDR gene polymorphisms and echocardiographic markers in Polish patients with cardiovascular disease

Aim: This work was designed to investigate the associations between vitamin D metabolites, VDR gene polymorphisms and echocardiographic markers in a population of patients with cardiovascular disease. Methods: Echocardiographic markers for 42 patients were determined with tissue Doppler techniques. PCR-restriction fragment length polymorphism analysis identified genetic variants ApaI, TaqI, BsmI and FokI. A validated UHPLC-MS/MS method determined vitamin D metabolites. Results: Patients with the ApaI-GT genotype exhibited a lower pressure gradient across the aortic valve than ApaI-TT carriers. BMI, ApaI-GT, TaqI-TC, aortic arch diameter and maximal pressure gradient were significant univariate predictors of hypertension. Conclusion: A potential link exists between VDR gene polymorphisms and cardiovascular function.

Gramine improves sepsis-induced myocardial dysfunction by binding to NF-κB p105 and inhibiting its ubiquitination

BACKGROUND

Sepsis and its associated heart failure are among the leading causes of death. Gramine, a natural indole alkaloid, can be extracted from a wide variety of raw plants, and it exhibits therapeutic potential in pathological cardiac hypertrophy. However, the effect of gramine on inflammatory cardiomyopathy, particularly sepsis-induced myocardial injury, remains an unexplored area.

PURPOSE

To determine the role of gramine in sepsis-induced myocardial dysfunction and explore its underlying mechanism.

STUDY DESIGN AND METHODS

In mice, sepsis was established by intraperitoneally injecting lipopolysaccharide (LPS, 10 mg/kg). Subsequently, the effects of gramine administration (50 or 100 mg/kg) on LPS-triggered cardiac dysfunction in mice were investigated. For in vitro studies, isolated primary cardiomyocytes were used to assess the effect of gramine (25 or 50 µM) on LPS-induced apoptosis and inflammation. Additionally, molecular docking, co-immunoprecipitation and ubiquitination analyzes were conducted to explore the underlying mechanisms.

RESULTS

Gramine visibly ameliorated sepsis-induced cardiac dysfunction, inflammatory response, and mortality in vivo. Moreover, it significantly alleviated LPS-induced apoptotic and inflammatory responses in vitro. Furthermore, target prediction for gramine using the SuperPred website indicated that the nuclear factor NF-κB p105 subunit was one of the molecules ranked in priority order with a high model accuracy and a high probability score. Molecular docking studies demonstrated that gramine effectively docked to the death domain of NF-κB p105. Mechanistic studies revealed that gramine suppressed the processing of NF-κB p105 to p50 by inhibiting NF-κB p105 ubiquitination. Additionally, the protective effect of gramine on cardiac injury was almost abolished by overexpressing NF-κB p105.

CONCLUSION

Gramine is a promising bioactive small molecule for treating sepsis-induced myocardial dysfunction, which acts by docking to NF-κB p105 and inhibiting NF-κB p105 ubiquitination, thus preventing its processing to NF-κB p50. Therefore, gramine holds potential as a clinical drug for treating myocardial depression during sepsis.

Vitamin D Receptor Activation Reduces Hepatic Inflammation via Enhancing Macrophage Autophagy in Cholestatic Mice

Macrophage autophagy dysfunction aggravates liver injury by activating inflammasomes, which can cleave pro-IL-1β to its active, secreted form. We investigated whether the vitamin D/vitamin D receptor (VDR) axis could up-regulate macrophage autophagy function to inhibit the activation of inflammasome-dependent IL-1β during cholestasis. Paricalcitol (PAL; VDR agonist) was intraperitoneally injected into bile duct-ligated mice for 5 days. Up-regulation of VDR expression by PAL reduced liver injury by reducing the oxidative stress-induced inflammatory reaction in macrophages. Moreover, PAL inhibited inflammasome-dependent IL-1β generation. Mechanistically, the knockdown of VDR increased IL-1β generation, whereas VDR overexpression exerted the opposite effect following tert-butyl hydroperoxide treatment. The inflammasome antagonist glyburide, the caspase-1-specific inhibitor YVAD, and the reactive oxygen species (ROS) scavenger N-acetyl-l-cysteine (NAC) blocked the increase in Vdr shRNA-induced IL-1β production. Interestingly, up-regulation of VDR also enhanced macrophage autophagy. Autophagy reduction impaired the up-regulation of VDR-inhibited macrophage inflammasome-generated IL-1β, whereas autophagy induction showed a synergistic effect with VDR overexpression through ROS-p38 mitogen-activated protein kinase (MAPK) pathway. This result was confirmed by p38 MAPK inhibitor, MAPK activator, and ROS inhibitor NAC. Collectively, PAL triggered macrophage autophagy by suppressing activation of the ROS-p38 MAPK pathway, which, in turn, suppressed inflammasome-generated cleaved, active forms of IL-1β, eventually leading to reduced inflammation. Thus, triggering the VDR may be a potential target for the anti-inflammatory treatment of cholestatic liver disease.

YTHDF2-regulated matrilin-3 mitigates post-reperfusion hemorrhagic transformation in ischemic stroke via the PI3K/AKT pathway

Hemorrhagic transformation can complicate ischemic strokes after recanalization treatment within a time window that requires early intervention. To determine potential therapeutic effects of matrilin-3, rat cerebral ischemia-reperfusion was produced using transient middle cerebral artery occlusion (tMCAO); intracranial hemorrhage and infarct volumes were assayed through hemoglobin determination and 2,3,5-triphenyltetrazoliumchloride (TTC) staining, respectively. Oxygen-glucose deprivation (OGD) modeling of ischemia was performed on C8-D1A cells. Interactions between matrilin-3 and YTH N6-methyladenosine RNA binding protein F2 (YTHDF2) were determined using RNA immunoprecipitation assay and actinomycin D treatment. Reperfusion after tMCAO modeling increased hemorrhage, hemoglobin content, and infarct volumes; these were alleviated by matrilin treatment. Matrilin-3 was expressed at low levels and YTHDF2 was expressed at high levels in ischemic brains. In OGD-induced cells, matrilin-3 was negatively regulated by YTHDF2. Matrilin-3 overexpression downregulated p-PI3K/PI3K, p-AKT/AKT, ZO-1, VE-cadherin and occludin, and upregulated p-JNK/JNK in ischemic rat brains; these effects were reversed by LY294002 (a PI3K inhibitor). YTHDF2 knockdown inactivated the PI3K/AKT pathway, inhibited inflammation and decreased blood-brain barrier-related protein levels in cells; these effects were reversed by matrilin-3 deficiency. These results indicate that YTHDF2-regulated matrilin-3 protected ischemic rats against post-reperfusion hemorrhagic transformation via the PI3K/AKT pathway and that matrilin may have therapeutic potential in ischemic stroke.

Physiological Evidence and Therapeutic Outcomes of Vitamin D on Cardiovascular Diseases

Vitamin D hormone is an important regulator of various physiological functions, and its deficiency is characterized by an imbalance in parathyroid hormone and calcium homeostasis. The role of vitamin D in cardiovascular physiology is well demonstrated in animal and humanbased studies. In this context, hyperlipidemia, increased atherogenic plaques, cardiac inflammation, hypertension, myocarditis, myocardial infarction, and heart failure are some of the commonest known conditions connected with vitamin D deficiency. Supplementation of vitamin D is recommended to achieve normal serum vitamin D concentrations, nonetheless, in clinical trials often seen discrepancies concerning the supplementation effects and effectiveness. This review summarizes the data on the role of vitamin D in cardiovascular health along with some recent clinical findings regarding the effects of vitamin D supplementation.

Calcitriol reverses age-related hypertension via downregulating renal AP1/AT1R pathway through regulating mitochondrial function

BACKGROUND

The vitamin D level in the blood is associated with the incidence of hypertension. The present study investigated whether or not calcitriol, an active form of vitamin D, reverses age-related hypertension.

METHODS

Young (3-month-old) and aged (12-month-old) C57BL/6 male mice were administered with or without calcitriol at 150 ng/kg per day by oral gavage for 8 weeks. Blood pressure was measured by tail-cuff plethysmography and telemetry, and superoxide production in renal tissue was assessed by fluorescence imaging, and the protein expression of AP1/AT1R signaling pathway was examined by Western blot.

RESULTS

We showed that 24-hour renal sodium excretion was impaired and blood pressure was increased in aged mice, which was related to the enhancement of renal AT1R expression and function. In addition, the expression of transcription factor AP1 (a dimer of c-Fos and c-Jun) and the binding of AP1 to the AT1R promoter region was significantly enhanced, accompanied by decreased nuclear translocation of Nrf2, abnormal mitochondrial function including decreased ATP production, NAD+/NADH ratio and mtDNA copy numbers, and increased reactive oxygen species. Calcitriol increased 24-hour urinary sodium excretion and reduced blood pressure in aged mice. Mechanically, calcitriol increased the nuclear translocation of Nrf2, improved mitochondrial function, reduced AP1 binding ability to AT1R promoter, which reversed enhanced AT1R expression and function, and lowered blood pressure in aged mice.

CONCLUSIONS

Our findings indicated that calcitriol reversed age-related hypertension via downregulating renal AP1/AT1R pathway through regulating mitochondrial function. Thus, calcitriol may be a valuable therapeutic strategy for age-related hypertension.

Effects of Vitamin D3 Supplementation and Aerobic Training on Autophagy Signaling Proteins in a Rat Model Type 2 Diabetes Induced by High-Fat Diet and Streptozotocin

The aim of this study was to investigate the combined effects of vitamin D3 supplementation and aerobic training on regulating the autophagy process in rats with type 2 diabetic induced by a high-fat diet and streptozotocin. A total of 40 Wistar rats were divided into five groups: normal control (NC), diabetic control (DC), diabetic + aerobic training (DAT), diabetic + vitamin D3 (DVD), and diabetic + aerobic training + vitamin D3 (DVDAT). The rats underwent eight weeks of aerobic training with an intensity of 60% maximum running speed for one hour, along with weekly subcutaneous injections of 10,000 units of vitamin D3. The protein levels of different autophagy markers were assessed in the left ventricular heart tissue. The results showed that the protein levels of AMPK, pAMPK, mTOR, and pmTOR were significantly lower in the DC group compared to the NC group. Conversely, the levels of ULK, Beclin-1, LC3II, Fyco, and Cathepsin D proteins were significantly higher in the DC group. However, the interventions of aerobic training and vitamin D3 supplementation, either individually or in combination, led to increased levels of AMPK, pAMPK, mTOR, and pmTOR, and decreased levels of ULK, Beclin-1, LC3II, Fyco, and Cathepsin D (p < 0.05). Additionally, the aerobic capacity in the DAT and DVDAT groups was significantly higher compared to the NC, DC, and DVD groups (p < 0.05). These findings suggest that type 2 diabetes is associated with excessive autophagy in the left ventricle. However, after eight weeks of vitamin D3 supplementation and aerobic training, a significant reduction in excessive autophagy was observed in rats with type 2 diabetes.

Unfolded Protein Response Signaling in Liver Disorders: A 2023 Updated Review

Endoplasmic reticulum (ER) is the site for synthesis and folding of secreted and transmembrane proteins. Disturbance in the functioning of ER leads to the accumulation of unfolded and misfolded proteins, which finally activate the unfolded protein response (UPR) signaling. The three branches of UPR-IRE1 (Inositol requiring enzyme 1), PERK (Protein kinase RNA-activated (PKR)-like ER kinase), and ATF6 (Activating transcription factor 6)-modulate the gene expression pattern through increased expression of chaperones and restore ER homeostasis by enhancing ER protein folding capacity. The liver is a central organ which performs a variety of functions which help in maintaining the overall well-being of our body. The liver plays many roles in cellular physiology, blood homeostasis, and detoxification, and is the main site at which protein synthesis occurs. Disturbance in ER homeostasis is triggered by calcium level imbalance, change in redox status, viral infection, and so on. ER dysfunction and subsequent UPR signaling participate in various hepatic disorders like metabolic (dysfunction) associated fatty liver disease, liver cancer, viral hepatitis, and cholestasis. The exact role of ER stress and UPR signaling in various liver diseases is not fully understood and needs further investigation. Targeting UPR signaling with drugs is the subject of intensive research for therapeutic use in liver diseases. The present review summarizes the role of UPR signaling in liver disorders and describes why UPR regulators are promising therapeutic targets.

Paricalcitol improved cardiac hypertrophy and fibrosis through upregulation of fibroblast growth factor-23 and downregulation of transforming growth factor-beta in a rat model of isoproterenol-induced cardiomyopathy

Acute cardiomyopathy is a significant global health concern and one of the leading causes of death in developed countries. Prior studies have shown an association between acute cardiomyopathy and low vitamin D levels. Although paricalcitol, a vitamin D receptor (VDR) activator, has demonstrated clinical benefits in patients with advanced kidney disease, its effect on cardiac remodeling in cardiomyopathy is unknown. This study aimed to investigate the relative effects of paricalcitol on cardiomyopathy in rats. Wistar-Kyoto rats were administered vehicle (sham control group) or isoproterenol to induce cardiomyopathy. Rats administered isoproterenol were subsequently treated with paricalcitol (experimental group) or vehicle (isoproterenol group). Picrosirius red and immunofluorescence staining were used to analyze cardiac fibrosis and hypertrophy. Immunohistochemistry staining was used to confirm the molecular mechanisms involved in isoproterenol-induced cardiomyopathy in rats. Injection of paricalcitol could reduce collagen and transforming growth factor-beta 1 (TGF-β1) levels while activating fibroblast growth factor receptor 1 (FGFR1) and fibroblast growth factor-23 (FGF23) without the help of Klotho, thereby reducing myocardial hypertrophy and fibrosis. As a VDR activator, paricalcitol reduces isoproterenol-induced cardiac fibrosis and hypertrophy by reducing the expression of TGF-β1 and enhancing the expression of VDR, FGFR1, and FGF23.

Adverse effect propensity: A new feature of Gulf War illness predicted by environmental exposures

A third of 1990-1 Gulf-deployed personnel developed drug/chemical-induced multisymptom illness, "Gulf War illness" (GWI). Veterans with GWI (VGWI) report increased drug/exposure adverse effects (AEs). Using previously collected data from a case-control study, we evaluated whether the fraction of exposures that engendered AEs ("AE Propensity") is increased in VGWI (it was); whether AE Propensity is related to self-rated "chemical sensitivity" (it did); and whether specific exposures "predicted" AE Propensity (they did). Pesticides and radiation exposure were significant predictors, with copper significantly "protective"-in the total sample (adjusted for GWI-status) and separately in VGWI and controls, on multivariable regression. Mitochondrial impairment and oxidative stress (OS) underlie AEs from many exposures irrespective of nominal specific mechanism. We hypothesize that mitochondrial toxicity and interrelated OS from pesticides and radiation position people on the steep part of the curve of mitochondrial impairment and OS versus symptom/biological disruption, amplifying impact of new exposures. Copper, meanwhile, is involved in critical OS detoxification processes.

Vitamin D3/VDR inhibits inflammation through NF-κB pathway accompanied by resisting apoptosis and inducing autophagy in abalone Haliotis discus hannai

Vitamin D3 is believed to be a contributing factor to innate immunity. Vitamin D receptor (VDR) has a positive effect on inhibiting nuclear factor κB (NF-κB)-mediated inflammation. The underlying molecular mechanisms remain unclear, particularly in mollusks. Consequently, this study will investigate the process of vitamin D3/VDR regulating NF-κB pathway and further explore their functions on inflammation, autophagy, and apoptosis in abalone Haliotis discus hannai. Results showed that knockdown of VDR by using siRNA and dsRNA of VDR in vitro and in vivo led to more intense response of NF-κB signaling to lipopolysaccharide and higher level of apoptosis and autophagy. In addition, 1,25(OH)2D3 stimulation after VDR silencing could partially alleviate apoptosis and induce autophagy. Overexpression of VDR restricted the K48-polyubiquitin chain-dependent inhibitor of κB (IκB) ubiquitination and apoptosis-associated speck-like protein containing CARD (ASC) oligomerization. Besides, VDR silencing resulted in increase of ASC speck formation. In further mechanistic studies, we showed that VDR can directly bind to IκB and IKK1 in vitro and in vivo. In the feeding trial, H&E staining, TUNEL, and electron microscope results showed that vitamin D3 deficiency (0 IU/kg) could recruit more basophilic cells and increase more TUNEL-positive apoptotic cells and lipid droplets (LDs) than vitamin D3 supplement (1000 IU/kg and 5000 IU/kg). In summary, abalone VDR plays a negative regulator role in NF-κB-mediated inflammation via interacting with IκB and inhibiting ubiquitin-dependent degradation of IκB. Vitamin D3 in combination with VDR is essential to establish a delicate balance between autophagy and apoptosis in response to inflammation.

The inhibitory effect of vitamin D on myocardial homocysteine levels involves activation of Nrf2-mediated methionine synthase

BACKGROUND

Homocysteine (Hcy) is a synthetic amino acid containing sulfhydryl group, which is an intermediate product of the deep metabolic pathway of methionine and cysteine. The abnormal increase in fasting plasma total Hcy concentration caused by various factors is called hyperhomocysteine (HHcy). HHcy is closely relevant to the occurrence and progression of diverse cardiovascular and cerebrovascular diseases, such as coronary heart disease, hypertension and diabetes, etc. Vitamin D/vitamin D receptor (VDR) pathway is pointed out that prevent cardiovascular disease by reducing serum homocysteine levels. Our research is designed to explore the potential mechanism of vitamin D in the prevention and treatment of HHcy.

METHODS AND RESULTS

The Hcy and 25(OH)D₃ levels in mouse myocardial tissue, serum or myocardial cells were detected using ELISA kits. The expression levels of VDR, Nrf2 and methionine synthase (MTR) were observed using Western blotting, immunohistochemistry and real time polymerase chain reaction (PCR). General information of the mice, including diet, water intake and body weight, was recorded. Vitamin D up-regulated the mRNA and protein expression of Nrf2 and MTR in mouse myocardial tissue and cells. CHIP assay determined that the combination of Nrf2 binding to the S1 site of the MTR promoter in cardiomyocytes using traditional PCR and real time PCR. Dual Luciferase Assay was applied to detect the transcriptional control of Nrf2 on MTR. The up-regulation effect of Nrf2 on MTR was verified by Nrf2 knockout and overexpression in cardiomyocytes. The role of Nrf2 in vitamin D inhibition of Hcy was revealed using Nrf2-knockdown HL-1 cells and Nrf2 heterozygous mice. Western blotting, real time PCR, IHC staining and ELISA showed that Nrf2 deficiency could restrain the increase in MTR expression and the decrease in Hcy level induced by vitamin D. The transcriptional activities of Nrf2/MTR were activated by vitamin D/VDR with a decrease in Hcy.

CONCLUSION

Vitamin D/VDR upregulates MTR in an Nrf2-dependent manner, thereby reducing the risk of HHcy.

Regulation of autophagy of the heart in ischemia and reperfusion

Ischemia/reperfusion (I/R) of the heart leads to increased autophagic flux. Preconditioning stimulates autophagic flux by AMPK and PI3-kinase activation and mTOR inhibition. The cardioprotective effect of postconditioning is associated with activation of autophagy and increased activity of NO-synthase and AMPK. Oxidative stress stimulates autophagy in the heart during I/R. Superoxide radicals generated by NADPH-oxidase acts as a trigger for autophagy, possibly due to AMPK activation. There is reason to believe that AMPK, GSK-3β, PINK1, JNK, hexokinase II, MEK, PKCα, and ERK kinases stimulate autophagy, while mTOR, PKCδ, Akt, and PI3-kinase can inhibit autophagy in the heart during I/R. However, there is evidence that PI3-kinase could stimulate autophagy in ischemic preconditioning of the heart. It was found that transcription factors FoxO1, FoxO3, NF-κB, HIF-1α, TFEB, and Nrf-2 enhance autophagy in the heart in I/R. Transcriptional factors STAT1, STAT3, and p53 inhibit autophagy in I/R. MicroRNAs could stimulate and inhibit autophagy in the heart in I/R. Long noncoding RNAs regulate the viability and autophagy of cardiomyocytes in hypoxia/reoxygenation (H/R). Nitric oxide (NO) donors and endogenous NO could activate autophagy of cardiomyocytes. Activation of heme oxygenase-1 promotes cardiomyocyte tolerance to H/R and enhances autophagy. Hydrogen sulfide increases cardiac tolerance to I/R and inhibits apoptosis and autophagy via mTOR and PI3-kinase activation.

Effects of Mitochondrial ATP-Sensitive Potassium Channel in Rats with Acute Myocardial Infarction and Its Association with the AKT/mTOR Pathway

BACKGROUND

Myocardial infarction is associated with the autophagy and apoptosis of cardiomyocytes, and the protein kinase B/mammalian target of rapamycin (AKT/mTOR) pathway plays a crucial role in this mechanism.

METHODS

Acute myocardial infarction rat models were assessed 0.5, 2, 4, and 6 hours after the induction of the myocardial infarction using hematoxylin and eosin staining, triphenyl tetrazolium chloride staining, myocardial enzyme measurements, and levels of autophagic activity. Additionally, diazoxide, 5-hydroxydecanoate, and LY294002 were intraperitoneally administered to rat models at peak myocardial injury to assess their effects on cardiac injury. The expression levels of autophagy-related and apoptosis-related proteins, as well as p-AKT and p-mTOR, were measured. Electron microscopy was used to assess the ultrastructure and the number of autophagosomes in the cardiac tissue.

RESULTS

We demonstrated that the degree of myocardial injury and the level of autophagy were significantly elevated in the experimental cohort compared with the control cohort. In addition, the myocardial infarct size was significantly smaller in diazoxide-treated acute myocardial infarction rats compared with untreated rats. Diazoxide also decreased the levels of myocardial injury markers, autophagy, and apoptosis, while it also induced the levels of AKT and mTOR phosphorylation, decreased the number of autophagosomes, and improved the myocardial ultrastructure of the acute myocardial infarction rats. 5-Hydroxydecanoate treatment resulted in an opposite effect to those observed upon diazoxide treatment. LY294002 was also able to reverse diazoxide treatment effects.

CONCLUSION

Peak levels of myocardial tissue injury and autophagy were observed 2 hours post-acute myocardial infarction induction in rats. Diazoxide treatment inhibited myocardial autophagy and apoptosis while protecting cardiac tissue from ischemic injury, which is likely to have proceeded through activation of the AKT/mTOR pathway.

Endoplasmic reticulum as a target in cardiovascular diseases: Is there a role for flavonoids?

Flavonoids are found in natural health products and plant-based foods. The flavonoid molecules contain a 15-carbon skeleton with the particular structural construction of subclasses. The most flavonoid's critical subclasses with improved health properties are the catechins or flavonols (e.g., epigallocatechin 3-gallate from green tea), the flavones (e.g., apigenin from celery), the flavanones (e.g., naringenin from citrus), the flavanols (e.g., quercetin glycosides from berries, onion, and apples), the isoflavones (e.g., genistein from soya beans) and the anthocyanins (e.g., cyanidin-3-O-glucoside from berries). Scientific data conclusively demonstrates that frequent intake of efficient amounts of dietary flavonoids decreases chronic inflammation and the chance of oxidative stress expressing the pathogenesis of human diseases like cardiovascular diseases (CVDs). The endoplasmic reticulum (ER) is a critical organelle that plays a role in protein folding, post-transcriptional conversion, and transportation, which plays a critical part in maintaining cell homeostasis. Various stimuli can lead to the creation of unfolded or misfolded proteins in the endoplasmic reticulum and then arise in endoplasmic reticulum stress. Constant endoplasmic reticulum stress triggers unfolded protein response (UPR), which ultimately causes apoptosis. Research has shown that endoplasmic reticulum stress plays a critical part in the pathogenesis of several cardiovascular diseases, including diabetic cardiomyopathy, ischemic heart disease, heart failure, aortic aneurysm, and hypertension. Endoplasmic reticulum stress could be one of the crucial points in treating multiple cardiovascular diseases. In this review, we summarized findings on flavonoids' effects on the endoplasmic reticulum and their role in the prevention and treatment of cardiovascular diseases.

Vitamin D Receptor Activation Targets ROS-Mediated Crosstalk Between Autophagy and Apoptosis in Hepatocytes in Cholestasic Mice

BACKGROUND & AIMS

Observational epidemiologic studies have associated vitamin D deficiency with cholestasis. We reported previously that activation of the vitamin D/vitamin D receptor (VDR) axis in cholangiocytes mitigates cholestatic liver injury by remodeling the damaged bile duct. However, the function of VDR in hepatocytes during cholestasis remains unclear.

METHODS

Paricalcitol (VDR agonist, 200 ng/kg) was injected intraperitoneally into bile duct-ligated mice every other day for 5 days. Primary hepatocytes and HepG2 hepatoma cells were transfected with Vdr short hairpin RNA, control short hairpin RNA, Vdr plasmid, control vector, Atg5 small interfering RNA (siRNA), and control siRNA. Liver histology, cell proliferation, and autophagy were evaluated.

RESULTS

Treatment with the VDR agonist paricalcitol improved liver injury in bile duct-ligated mice by up-regulating VDR expression in hepatocytes, which in turn reduced hepatocyte apoptosis by inhibiting reactive oxygen species (ROS) generation via suppressing the Ras-related C3 botulinum toxin substrate 1/reduced nicotinamide adenine dinucleotide phosphate oxidase 1 pathway. Mechanistically, upon exposure to an ROS-inducing compound, Vdr siRNA contributed to apoptosis, whereas the Vdr overexpression caused resistance to apoptosis. Interestingly, up-regulated VDR expression also increased the generation of autophagosomes and macroautophagic/autophagic flux, which was the underlying mechanism for reduced apoptosis following VDR activation. Autophagy depletion impaired the positive effects of VDR overexpression, whereas autophagy induction was synergystic with VDR overexpression. Importantly, up-regulation of VDR promoted autophagy activation by suppressing the activation of the extracellular signal-regulated kinase (ERK)/p38 mitogen-activated protein kinase (p38MAPK) pathway. Thus, a p38MAPK inhibitor abrogated the Vdr siRNA-induced decrease in autophagy and the Vdr siRNA-induced increase in apoptosis. In contrast, a Mitogen-activated protein kinase kinase (MEK)/ERK activator prevented the enhancement of autophagy and decreased apoptosis following Vdr overexpression. Moreover, the ROS inhibitor N-acetylcystein (NAC) blocked Vdr siRNA-enhanced activation of the ERK/p38MAPK pathway.

CONCLUSIONS

VDR activation mitigated liver cholestatic injury by reducing autophagy-dependent hepatocyte apoptosis and suppressing the activation of the ROS-dependent ERK/p38MAPK pathway. Thus, VDR activation may be a potential target for the treatment of cholestatic liver disease.

Vitamin D Receptor Regulates Autophagy to Inhibit Apoptosis and Promote Proliferation in Hepatocyte Injury

BACKGROUND

Oxidative stress is an important mechanism in liver ischemia/reperfusion (I/R) injury. Hepatocyte apoptosis and proliferation occur in parallel with liver I/R injury, and the degree of apoptosis and proliferation determines the effects on hepatocytes. Vitamin D receptor (VDR) can lessen liver I/R injury, but previous studies focused mostly on inflammation and immunity.

METHODS

H₂O₂ was used to induce hepatocyte injury. Before treatment with H₂O₂, Hep-3B cells were pretreated with paricalcitol (PC) and siRNA-VDR. Rapamycin and chloroquine were also applied in the study.

RESULTS

The number of apoptotic cells was measured with an annexin V (AV) -fluorescein isothiocyanate apoptosis detection kit. Expression of proteins was measured by western blotting. As compared with the H₂O₂+Hep-3B group, levels of AV/PI, cleaved caspase-3, and p62 were lower, and expression levels of Bcl-2, proliferating cell nuclear antigen, and VDR were higher, in the PC+H₂O₂+Hep-3B group. When the VDR gene was silenced by siRNA-VDR in the siRNA-VDR+H₂O₂+Hep-3B group, expressions of AV/PI, cleaved caspase-3, and p62 were upregulated, and expressions of Bcl-2, proliferating cell nuclear antigen, and VDR were downregulated, as compared with values for the siRNA-NC+H₂O₂+Hep-3B group. Treatment with rapamycin or chloroquine partially reversed the effect of PC and siRNA-VDR on apoptosis and proliferation.

CONCLUSIONS

VDR mediates hepatocyte apoptosis and proliferation through autophagy.

SMAD3 interacts with vitamin D receptor and affects vitamin D-mediated oxidative stress to ameliorate cerebral ischaemia-reperfusion injury

Cerebral ischaemia/reperfusion (I/R) injury is caused by blood flow restoration after an ischaemic insult, and effective treatments targeting I/R injury are still insufficient. Oxidative stress plays a critical role in the pathogenesis of cerebral I/R injury. This study investigated whether vitamin D receptor (VDR) could inhibit oxidative stress caused by cerebral I/R injury and explored the detailed mechanism. VDR was highly expressed in brain tissues of mice with cerebral I/R injury. Pretreatment with the active vitamin D calcitriol and synthetic vitamin D analogue paricalcitol (PC) reduced autophagy and apoptosis, improved neurological deficits and decreased infarct size in mice after cerebral I/R. Calcitriol or PC upregulated VDR expression to prevent cerebral I/R injury by affecting oxidative stress. Silencing of VDR reversed the protective effects of calcitriol or PC on brain tissues in mice with cerebral I/R. The bioinformatics analysis revealed that VDR interacted with SMAD family member 3 (SMAD3). It was validated through the chromatin immunoprecipitation assay that SMAD3 can bind to the VDR promoter and VDR can bind to the SMAD3 promoter. Collectively, these findings provide evidence that reciprocal activation between SMAD3 and VDR transcription factors defines vitamin D-mediated oxidative stress to prevent cerebral I/R injury.

Vitamin D supplementation modulates autophagy in the pristane-induced lupus model

Introduction/objectives

Clinical evidence of skeletal muscle involvement is not uncommon in systemic lupus erythematosus (SLE). Because of the poor understanding of signaling pathways involved in SLE muscle wasting, the  aim of this study was to evaluate the effects of vitamin D supplementation on skeletal muscle in mice with pristane-induced lupus.

Methods

Balb/c mice with lupus-like disease induced by pristane injection were randomized into three groups: pristane-induced lupus (PIL; n = 10), pristane-induced lupus + vitamin D supplementation (PIL + VD; n = 10) and healthy controls (CO; n = 8). Physical function was evaluated on days 0, 60, 120 and 180. The tibialis anterior and gastrocnemius muscles were collected to evaluate myofiber cross-sectional area (CSA) and protein expression.

Results

The PIL + VD group showed lower muscle strength compared to the CO and PIL groups at different time points. PIL mice showed similar myofiber CSA compared to CO and PIL + VD groups. LC3-II expression was higher in PIL compared to CO and PIL + VD groups. MyoD expression was higher in PIL mice compared to PIL + VD, while myostatin expression was higher in PIL + VD than PIL group. Myogenin expression levels were decreased in the PIL + VD group compared with the CO group. The Akt, p62 and MuRF expressions and mobility assessment showed no significance.

Conclusions

Changes in skeletal muscle in PIL model happen before CSA reduction, possibly due to autophagy degradation, and treatment with Vitamin D has a impact on physical function by decreasing muscle strength and time of fatigue.. Vitamin D supplementation has a potential role modulating physical parameters and signaling pathways in muscle during pristane-induced lupus model.

The Role of CD147 in Pathological Cardiac Hypertrophy Is Regulated by Glycosylation

CD147, also known as EMMPRIN or basigin, is a transmembrane glycoprotein receptor that activates matrix metalloproteinases and promotes inflammation. CD147 function is regulated by posttranslational modifications of which glycosylation has attracted the most attention. In this study, we demonstrated that glycosylated CD147 was the dominant form in heart tissue, and its levels were markedly elevated in response to transverse aortic constriction (TAC). Adeno-associated virus 9-mediated, cardiac-specific overexpression of wild-type CD147 in mice significantly promoted pressure overload-induced pathological cardiac remodeling accompanied by augmented oxidative stress and ferroptosis. By contrast, mutations of CD147 glycosylation sites notably weakened these detrimental effects of CD147. Mechanistically, CD147 exacerbated TAC-induced pathological cardiac remodeling via direct binding with the adaptor molecule TRAF2 and subsequent activation of TAK1 signalling, which was dependent on glycosylation of CD147. Collectively, our findings provide the first evidence that CD147 promoted pathological cardiac remodeling and dysfunction in a glycosylation-dependent manner through binding the adaptor protein TRAF2 and activating the downstream TRAF2-TAK1 signalling pathway. Thus, glycosylation of CD147 may be a potent interventional target for heart failure treatment.

New insights into the role of melatonin in diabetic cardiomyopathy

Diabetic cardiovascular complications and impaired cardiac function are considered to be the main causes of death in diabetic patients worldwide, especially patients with type 2 diabetes mellitus (T2DM). An increasing number of studies have shown that melatonin, as the main product secreted by the pineal gland, plays a vital role in the occurrence and development of diabetes. Melatonin improves myocardial cell metabolism, reduces vascular endothelial cell death, reverses microcirculation disorders, reduces myocardial fibrosis, reduces oxidative and endoplasmic reticulum stress, regulates cell autophagy and apoptosis, and improves mitochondrial function, all of which are the characteristics of diabetic cardiomyopathy (DCM). This review focuses on the role of melatonin in DCM. We also discuss new molecular findings that might facilitate a better understanding of the underlying mechanism. Finally, we propose potential new therapeutic strategies for patients with T2DM.

The transcription factor interferon regulatory factor-1 is an endogenous mediator of myocardial ischemia reperfusion injury

Myocardial ischemia reperfusion (MIR) injury negatively affects the prognosis of acute myocardial infarction (AMI), while effective suppression of MIR injury remains a largely unmet clinical need. Interferon regulatory factors (IRF) are key players in chronic cardiac disorders such as cardiac remodeling. However, their roles in acute MIR injury remain largely unknown. In the current study, microarray data indicated that IRF1 expression was consistently changed in the human ischemic heart and ischemic reperfused mouse heart. Western blot analysis confirmed the expression alterations of IRF1 in ischemic reperfused mouse heart. Cardiac-specific IRF1 knockdown significantly decreased infarct size, improved cardiac function, and suppressed myocardial apoptosis after MIR injury. Conversely, cardiac-specific IRF1 overexpression significantly promoted MIR injury. Further investigation revealed that IRF1 transcriptionally regulated the expression of inducible nitric oxide synthase (iNOS), and augmented oxidative stress. Taken together, we presented the first direct evidence that IRF1 served as a mediator of MIR injury, and IRF1 may represent a potential therapeutic target for alleviating MIR injury.

EGCG protects against myocardial I/RI by regulating lncRNA Gm4419-mediated epigenetic silencing of the DUSP5/ERK1/2 axis

BACKGROUND

Epigallocatechin gallate (EGCG) has attracted increasing attention due to its beneficial effect on cardiovascular health. The aim of this study was to investigate the underlying mechanism by which EGCG protects against myocardial ischaemia/reperfusion injury (I/RI).

METHODS

Murine myocardial I/RI and H2O2-induced cardiomyocyte injury models were established to evaluate the therapeutic effects of EGCG. In the myocardial I/RI mouse model, the echocardiographic parameters of ejection fraction (EF) and fraction shortening (FS) levels, infarct size, histological evaluation and transmission electron microscopy (TEM) were used to evaluate cardiac tissue damage and autophagy. MTT assays, TUNEL staining, flow cytometry and immunofluorescence (IF) were used to monitor cell viability, apoptosis and autophagy in vitro. qRT-PCR and western blotting were used to determine the mRNA and protein levels of key molecules, respectively. The epigenetic regulation of DUSP5 was assessed via RNA immunoprecipitation (RIP), RNA pull-down and chromatin immunoprecipitation (ChIP) assays.

RESULTS

EGCG significantly improved cardiac function, reduced infarct size, enhanced cell viability and inhibited autophagic activity in both myocardial I/RI mouse models and H2O2-induced cardiomyocyte injury models. Moreover, EGCG suppressed H2O2- or myocardial I/R-increased Gm4419 expression, and Gm4419 overexpression dramatically abolished EGCG-mediated protective effects against myocardial I/RI. Mechanistically, Gm4419 epigenetically suppressed DUSP5 by recruiting EZH2, thus activating ERK1/2 pathway-mediated autophagy. Furthermore, the in vivo experiments further verified that the Gm4419-mediated disruptive effects of EGCG on myocardial I/RI were potentiated by DUSP5 knockdown but attenuated by DUSP5 overexpression.

CONCLUSIONS

In conclusion, our findings demonstrated that EGCG protected against myocardial I/RI by modulating Gm4419/DUSP5/ERK1/2-mediated autophagy.

Hypertrophic preconditioning attenuates myocardial ischemia/reperfusion injury through the deacetylation of isocitrate dehydrogenase 2

To test the hypothesis that transient nonischemic stimulation of hypertrophy would render the heart resistant to subsequent ischemic stress, short-term transverse aortic constriction (TAC) was performed in mice and then withdrawn for several days by aortic debanding, followed by subsequent myocardial exposure to ischemia/reperfusion (I/R). Following I/R injury, the myocardial infarct size and apoptosis were markedly reduced, and contractile function was significantly improved in the TAC preconditioning group compared with the control group. Mechanistically, hypertrophic preconditioning remarkably alleviated I/R-induced oxidative stress, as evidenced by the increased reduced nicotinamide adenine dinucleotide phosphate (NADPH)/nicotinamide adenine dinucleotide phosphate (NADP) ratio, increase in the reduced glutathione (GSH)/oxidized glutathione (GSSH) ratio, and reduced mitochondrial reactive oxygen species (ROS) production. Moreover, TAC preconditioning inhibited caspase-3 activation and mitigated the mitochondrial impairment by deacetylating isocitrate dehydrogenase 2 (IDH2) via a sirtuin 3 (SIRT3)-dependent mechanism. In addition, the expression of a genetic deacetylation mimetic IDH2 mutant (IDH2 K413R) in cardiomyocytes, which increased IDH2 enzymatic activity and decreased mitochondrial ROS production, and ameliorated I/R injury, whereas the expression of a genetic acetylation mimetic (IDH2 K413Q) in cardiomyocytes abolished these protective effects of hypertrophic preconditioning. Furthermore, both the activity and expression of the SIRT3 protein were markedly increased in preconditioned mice exposed to I/R. Treatment with an adenovirus encoding SIRT3 partially emulated the actions of hypertrophic preconditioning, whereas genetic ablation of SIRT3 in mice blocked the cardioprotective effects of hypertrophic preconditioning. The present study identifies hypertrophic preconditioning as a novel endogenous self-defensive and cardioprotective strategy for cardiac I/R injury that induces IDH2 deacetylation through a SIRT3-dependent mechanism. A therapeutic strategy targeting IDH2 may be a promising treatment for cardiac ischemic injury.

Vitamin D in autophagy signaling for health and diseases: Insights on potential mechanisms and future perspectives

Vitamin D regulates the pleiotropic effect to maintain cellular homeostasis and epidemiological evidence establishes an association between vitamin D deficiency and various human diseases. Here, the role of autophagy, the cellular self-degradation process, in vitamin D-dependent function is documented in different cellular settings and discussed the molecular aspects for treating chronic inflammatory, infectious diseases, and cancer. Vitamin D activates autophagy through a genomic and non-genomic signaling pathway to influence a wide variety of physiological functions of different body organs along with bone health and calcium metabolism. Moreover, it induces autophagy as a protective mechanism to inhibit oxidative stress and apoptosis to regulate cell proliferation, differentiation, and immune modulation. Furthermore, vitamin D and its receptor regulate autophagy signaling to control inflammation and host immunity by activating antimicrobial defense mechanisms. Vitamin D has been revealed as a potent anticancer agent and induces autophagy to increase the response to radiation and chemotherapeutic drugs for potential cancer therapy. Increasing vitamin D levels in the human body through timely exposure to sunlight or vitamin D supplements could activate autophagy as part of the homeostasis mechanism to prevent multiple human diseases and aging-associated dysfunctions.

Unfolded protein response during cardiovascular disorders: a tilt towards pro-survival and cellular homeostasis

The endoplasmic reticulum (ER) is an organelle that orchestrates the production and proper assembly of an extensive types of secretory and membrane proteins. Endoplasmic reticulum stress is conventionally related to prolonged disruption in the protein folding machinery resulting in the accumulation of unfolded proteins in the ER. This disruption is often manifested due to oxidative stress, Ca²⁺ leakage, iron imbalance, disease conditions which in turn hampers the cellular homeostasis and induces cellular apoptosis. A mild ER stress is often reverted back to normal. However, cells retaliate to acute ER stress by activating the unfolded protein response (UPR) which comprises three signaling pathways, Activating transcription factor 6 (ATF6), inositol requiring enzyme 1 alpha (IRE1α), and protein kinase RNA-activated-like ER kinase (PERK). The UPR response participates in both protective and pro-apoptotic responses and not much is known about the mechanistic aspects of the switch from pro-survival to pro-apoptosis. When ER stress outpaces UPR response then cell apoptosis prevails which often leads to the development of various diseases including cardiomyopathies. Therefore, it is important to identify molecules that modulate the UPR that may serve as promising tools towards effective treatment of cardiovascular diseases. In this review, we elucidated the latest advances in construing the contribution imparted by the three arms of UPR to combat the adverse environment in the ER to restore cellular homeostasis during cardiomyopathies. We also summarized the various therapeutic agents that plays crucial role in tilting the UPR response towards pro-survival.

Metal ion homeostasis with emphasis on zinc and copper: Potential crucial link to explain the non-classical antioxidative properties of vitamin D and melatonin

Metal ion homeostasis is an essential physiological mechanism necessary for achieving an adequate balance of these ions' concentrations in the different cellular compartments. This fact is of great importance because both an excess and a deficiency of cellular metal ion levels are usually equally harmful due to the exacerbated increase in oxidative stress that may occur in both cases. Metal ion homeostasis ensures an equilibrium among multiple functions associated with the body's antioxidative defense network controlled by metallic micronutrients such as zinc and copper, some of the central regulators of redox processes. These micronutrients significantly modulate the activity of some isoforms of superoxide dismutase (SOD) and other enzymes such as metallothioneins (MTs) and ceruloplasmin (CP), which are directly or indirectly involved in the regulation of redox homeostasis. Although it is well known that both melatonin (MEL) and vitamin D have important roles as natural antioxidants, often some of these effects are related to their actions on antioxidative processes dependent on metal ions. Thus, in addition to their classical antioxidative properties usually associated with mitochondrial effects, it is known that MEL and vitamin D modulate the expression and activity of Cu/Zn-dependent SOD isoforms, MTs and CP; function as copper chelators and regulate genomic and non-genomic mechanisms related to the zinc transport. This review summarizes the main findings related to the crucial participation of zinc and copper in physiological antioxidative status and their relationship with the non-classical antioxidant effects of MEL and vitamin D, suggesting a potential synergism among these four micronutrients.

Paricalcitol inhibits oxidative stress-induced cell senescence of the bile duct epithelium dependent on modulating Sirt1 pathway in cholestatic mice

BACKGROUND

Clinical studies indicate that vitamin D receptor (VDR) expression is reduced in primary biliary cirrhosis patient livers. However, the mechanism by which activated VDR effect cholestatic liver injury remains unclear.

METHODS

Mice were injected intraperitoneally with the VDR agonist paricalcitol or a vehicle 3 days prior to bile duct ligation (BDL) and for 5 or 28 days after surgery. The analyses of liver morphology and necrotic areas were based on H&E staining. Serum biochemical indicators of liver damage were analyzed by commercial kits. The mechanisms of paricalcitol on cholestatic liver injury were determined by Western blot analysis.

RESULTS

Paricalcitol ameliorated the BDL-induced liver damage in mice. Paricalcitol increased the proliferation of BECs to promote the repair of the bile duct. Paricalcitol also reduced the BDL-induced oxidative stress level in the mice. Mechanistic analysis revealed that paricalcitol decreased the number of SA-β-gal-positive cells and downregulated the expression of p53, p21 and p16 proteins which was associated with reducing oxidative stress. Additionally, paricalcitol exerted the inhibitory effect of cell senescence was through reducing DNA damage and promoting DNA repair. Interesting, we found that paricalcitol prevented the downregulation of oxidative stress-induced Sirt1 expression in the BDL mice and t-BHP-induced BECs models. Moreover, paricalcitol suppressed cell senescence through a Sirt1-dependent pathway. These results were confirmed by antioxidant ALCAR and the Sirt1 inhibitor EX-527.

CONCLUSION

Paricalcitol alleviated cholestatic liver injury through promoting the repair of damaged bile ducts and reducing oxidative stress-induced cell senescence of the bile duct via modulating Sirt1 pathway.

Hypertrophic Preconditioning Attenuates Myocardial Ischaemia-Reperfusion Injury by Modulating SIRT3-SOD2-mROS-Dependent Autophagy

Background

Ischaemic preconditioning elicited by brief periods of coronary occlusion and reperfusion protects the heart from a subsequent prolonged ischaemic insult. Here, we test the hypothesis that short‐term non‐ischaemic stimulation of hypertrophy renders the heart resistant to subsequent ischaemic injury.

Methods and Results

Transient transverse aortic constriction (TAC) was performed for 3 days in mice and then withdrawn for 4 days by aortic debanding, followed by subsequent exposure to myocardial ischaemia‐reperfusion (I/R) injury. Following I/R injury, myocardial infarct size and apoptosis were significantly decreased, and cardiac dysfunction was markedly improved in the TAC preconditioning group compared with the control group. Mechanistically, TAC preconditioning markedly suppressed I/R‐induced autophagy and preserved autophagic flux by deacetylating SOD2 via a SIRT3‐dependent mechanism. Moreover, treatment with an adenovirus encoding SIRT3 partially mimicked the effects of hypertrophic preconditioning, whereas genetic ablation of SIRT3 in mice blocked the cardioprotective effects of hypertrophic preconditioning. Furthermore, in vivo lentiviral‐mediated knockdown of Beclin 1 in the myocardium ameliorated the I/R‐induced impairment of autophagic flux and was associated with a reduction in cell death, whereas treatment with a lentivirus encoding Beclin 1 abolished the cardioprotective effect of TAC preconditioning.

Conclusions

The present study identifies TAC preconditioning as a novel strategy for induction of an endogenous self‐defensive and cardioprotective mechanism against cardiac injury. Specifically, TAC preconditioning reduced myocardial autophagic cell death in a SIRT3/SOD2 pathway‐dependent manner.

The long and winding road to target protein misfolding in cardiovascular diseases

BACKGROUND

In the last decades, cardiovascular diseases (CVD) have remained the first leading cause of mortality and morbidity in the world. Although several therapeutic approaches have been introduced in the past, the development of novel treatments remains an important research goal, which is hampered by the lack of understanding of key mechanisms and targets. Emerging evidences in recent years indicate the involvement of misfolded proteins aggregation and the derailment of protein quality control in the pathogenesis of cardiovascular diseases. Several potential interventions targeting protein quality control have been translated from the bench to the bedside to effectively employ the misfolded proteins as promising therapeutic targets for cardiac diseases, but with trivial results.

DESIGN

In this review, we describe the recent progresses in preclinical and clinical studies of protein misfolding and compromised protein quality control by selecting and reporting studies focusing on cardiovascular diseases including cardiomyopathies, cardiac amyloidosis, atherosclerosis, atrial fibrillation and thrombosis.

RESULTS

In preclinical models, modulators of several molecular targets (eg heat shock proteins, unfolded protein response, ubiquitin protein system, autophagy and histone deacetylases) have been tested in various conditions with promising results although lacking an adequate transition towards clinical setting.

CONCLUSIONS

At present, no therapeutic strategies have been reported to attenuate proteotoxicity in patients with CVD due to a lack of specific biomarkers for pinpointing upstream events in protein folding defects at a subclinical stage of the diseases requiring an intensive collaboration between basic scientists and clinicians.

Activation of Paraventricular Melatonin Receptor 2 Mediates Melatonin-Conferred Cardioprotection Against Myocardial Ischemia/Reperfusion Injury

Previous studies have shown that melatonin (Mel) can effectively ameliorate myocardial ischemia/reperfusion (MI/R) injury, but the mechanism is yet to be fully elucidated. Mel receptors are expressed in the paraventricular nucleus (PVN), which is also involved in regulating cardiac sympathetic nerve activity. The aim of this study was to examine whether Mel receptors in the PVN are involved in the protective effects of Mel against MI/R injury. The results of quantitative polymerase chain reaction, western blot, and immunofluorescence assays indicated that Mel receptor 2 (MT2) expression in the PVN was upregulated after MI/R. Intraperitoneal administration of Mel significantly improved post-MI/R cardiac function and reduced the infarct size, whereas shRNA silencing of MT2 in the PVN partially blocked this effect. Intraperitoneal administration of Mel reduced sympathetic nerve overexcitation caused by MI/R, whereas shRNA silencing of MT2 in the PVN partially diminished this effect. Furthermore, enzyme-linked immunosorbent assay and western blot results indicated that intraperitoneal administration of Mel lowered the levels of inflammatory cytokines in the PVN after MI/R injury, whereas the application of sh-MT2 in the PVN reduced this effect of Mel. Mel significantly reduced the levels of NF-κB after astrocyte oxygen and glucose deprivation/reoxygenation injury, and this effect was offset when MT2 was silenced. The above experimental results suggest that MT2 in the PVN partially mediated the protective effects of Mel against MI/R injury, and its underlying mechanisms may be related to postactivation amelioration of PVN inflammation and reduction of cardiac sympathetic nerve overexcitation.

Hypertrophic preconditioning cardioprotection after myocardial ischaemia/reperfusion injury involves ALDH2-dependent metabolism modulation

Brief episodes of ischaemia and reperfusion render the heart resistant to subsequent prolonged ischaemic insult, termed ischaemic preconditioning. Here, we hypothesized that transient non-ischaemic stress by hypertrophic stimulation would induce endogenous cardioprotective signalling and enhance cardiac resistance to subsequent ischaemic damage. Transient transverse aortic constriction (TAC) or Ang-Ⅱ treatment was performed for 3-7 days in male mice and then withdrawn for several days by either aortic debanding or discontinuing Ang-Ⅱ treatment, followed by subsequent exposure to regional myocardial ischaemia by in situ coronary artery ligation. Following ischaemia/reperfusion (I/R) injury, myocardial infarct size and apoptosis were markedly reduced and contractile function was significantly improved in the TAC preconditioning group compared with that in the control group. Similar results were observed in mice receiving Ang-Ⅱ infusion. Mechanistically, TAC preconditioning enhanced ALDH2 activity, promoted AMPK activation and improved mitochondrial energy metabolism by increasing myocardial OXPHOS complex expression, elevating the mitochondrial ATP content and improving viable myocardium glucose uptake. Moreover, TAC preconditioning significantly mitigated I/R-induced myocardial iNOS/gp91^phox activation, inhibited endoplasmic reticulum stress and ameliorated mitochondrial impairment. Using a pharmacological approach to inhibit AMPK signalling in the presence or absence of preconditioning, we demonstrated AMPK-dependent protective mechanisms of TAC preconditioning against I/R injury. Furthermore, treatment with adenovirus-encoded ALDH2 partially emulated the actions of hypertrophic preconditioning, as evidenced by improved mitochondrial metabolism, inhibited oxidative stress-induced mitochondrial damage and attenuated cell death through an AMPK-dependent mechanism, whereas genetic ablation of ALDH2 abrogated the aforementioned actions of TAC preconditioning. The present study demonstrates that preconditioning with hypertrophic stress protects the heart from I/R injury via mechanisms that improve mitochondrial metabolism, reduce oxidative/nitrative stress and inhibit apoptosis. ALDH2 is obligatorily required for the development of cardiac hypertrophic preconditioning and acts as the mediator of this process.

Pretreatment of Huoxue Jiedu Formula Ameliorates Myocardial Ischaemia/Reperfusion Injury by Decreasing Autophagy via Activation of the PI3K/AKT/mTOR Pathway

Background: Myocardial ischaemia/reperfusion (I/R) results in myocardial injury via excessive autophagy. Huoxue Jiedu Formula (HJF) has been widely applied in China for the treatment of ischaemic heart disease. However, the mechanisms of HJF are still poorly understood. Thus, the present experiment was designed to observe the effects of HJF on myocardial I/R injury and explore the possible mechanism.

Methods: Myocardial injury in rats subjected to myocardial I/R was reflected by nitrotetrazolium blue chloride staining, thioflavin S staining, serum creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT). Autophagy was determined by electron microscopy, laser confocal microscopy, Q-PCR and western blot. The possible pathway was predicted by network pharmacology and validated in vivo and in vitro.

Results: Pretreatment of HJF decreased the no-reflow area, infarcted area, serum CK-MB levels and serum cTnT levels in I/R rat model. In addition, pretreatment of HJF decreased autophagy in heart tissues (decrease in Beclin-1 and LC3-II, and increase in Bcl-2, p62 and ratio of LC3-I/LC3-II). In the vivo study, pretreatment of HJF significantly decreased hypoxia/reoxygenation (H/R)-induced autophagy in H9C2 cells. Network pharmacology was applied to predict the possible mechanism by which HJF affects cardiac autophagy, and the PI3K/AKT/mTOR signalling pathway was the most significantly enriched pathway. And experimental studies demonstrated that pretreatment of HJF increased the phosphorylation of AKT and mTOR, and the effects of HJF on autophagy would be offset by PI3K inhibitor LY294002.

Conclusion: Pretreatment of HJF ameliorates myocardial I/R injury by decreasing autophagy through activating PI3K/AKT/mTOR pathway.

Antagonistic effect of VDR/CREB1 pathway on cadmium-induced apoptosis in porcine spleen

Cadmium (Cd) is a toxic trace element that can enter the environment with industrial waste and accumulate in the body but the health effects of Cd on ternary pigs are still lacking in research. In order to explore the effect of Cd on the apoptosis of pig spleen and its mechanism, this study chose ternary pig as the research object to detect relevant indicators in pig spleen under Cd exposure. The results of this study showed that Cd exposure can induce apoptosis by promoting the absorption of various toxic trace elements in the spleen and inducing oxidative stress. We also found that the mechanism of Cd-induced apoptosis is closely related to the VDR/CREB1 pathway. On the one hand, Cd exposure can activate VDR, and indirectly regulate the CYP family, affecting the normal function of the spleen. On the other hand, VDR and its downstream genes antagonize the toxicity of Cd by maintaining the stability of the mitochondrial-related endoplasmic reticulum membrane structure. Our research will help researchers to further understand the physiological toxicity of Cd.

Short-term Effects of Alfacalcidol on Hospital Length of Stay in Patients Undergoing Valve Replacement Surgery: A Randomized Clinical Trial

PURPOSE

Vitamin D deficiency is highly prevalent in critically ill patients, and has been associated with more prolonged length of hospital stay and poor prognosis. Patients undergoing open-heart surgery are at higher risk due to the associated life-threatening postoperative complications. This study investigated the effect of alfacalcidol treatment on the length of hospital stay in patients undergoing valve-replacement surgery.

METHODS

This single-center, randomized, open-label, controlled trial was conducted at El-Demerdash Cardiac Academy Hospital (Cairo, Egypt), from April 2017 to January 2018. This study included adult patients undergoing valve-replacement surgery who were randomized to the intervention group (n = 47; alfacalcidol 2 μg/d started 48 h before surgery and continued throughout the hospital stay) or to the control group (n = 42). The primary end points were lengths of stay (LOS) in the intensive care unit (ICU) and in the hospital. Secondary end points were the prevalence of postoperative hospital-acquired infections, cardiac complications, and in-hospital mortality.

FINDINGS

A total of 86 patients were included in the final analysis, with 51 (59.3%) being vitamin D deficient on hospital admission. Treatment with alfacalcidol was associated with a statistically significant decrease in ICU LOS (hazard ratio = 1.61; 95% CI, 1.77-2.81; P = 0.041) and hospital LOS (hazard ratio = 1.63; 95% CI, 1.04-2.55; P = 0.034). Treated patients had a significantly lower postoperative infection rate than did the control group (35.5% vs 56.1%; P = 0.017). The median epinephrine dose was lower in the intervention group compared to that in the control group (5.9 vs 8.2 mg; P = 0.019). The rate of in-hospital mortality was not significantly different between the 2 groups.

IMPLICATIONS

Early treatment with 2 μg of alfacalcidol in patients undergoing valve-replacement surgery is promising and well tolerated. This effect may be attributed to its immunomodulatory and cardioprotective mechanisms. ClinicalTrials.gov identifier: NCT04085770.

Vitamin D Attenuates Ischemia/Reperfusion-Induced Cardiac Injury by Reducing Mitochondrial Fission and Mitophagy

Myocardial infarction is the leading cause of morbidity and mortality worldwide. Although myocardial reperfusion after ischemia (I/R) is an effective method to save ischemic myocardium, it can cause adverse reactions, including increased oxidative stress and cardiomyocyte apoptosis. Mitochondrial fission and mitophagy are essential factors for mitochondrial quality control, but whether they play key roles in cardiac I/R injury remains unknown. New pharmacological or molecular interventions to alleviate reperfusion injury are currently considered desirable therapies. Vitamin D₃ (Vit D₃) regulates cardiovascular function, but its physiological role in I/R-exposed hearts, especially its effects on mitochondrial homeostasis, remains unclear. An in vitro hypoxia/reoxygenation (H/R) model was established in H9c2 cells to simulate myocardial I/R injury. H/R treatment significantly reduced H9c2 cell viability, increased apoptosis, and activated caspase 3. In addition, H/R treatment increased mitochondrial fission, as manifested by increased expression of phosphorylated dynein-related protein 1 (p-Drp1) and mitochondrial fission factor (Mff) as well as increased mitochondrial translocation of Drp1. Treatment with the mitochondrial reactive oxygen species scavenger MitoTEMPO increased cell viability and decreased mitochondrial fission. H/R conditions elicited excessive mitophagy, as indicated by increased expression of BCL2-interacting protein 3 (BNIP3) and light chain (LC3BII/I) and increased formation of autolysosomes. In contrast, Vit D₃ reversed these effects. In a mouse model of I/R, apoptosis, mitochondrial fission, and mitophagy were induced. Vit D₃ treatment mitigated apoptosis, mitochondrial fission, mitophagy, and myocardial ultrastructural abnormalities. The results indicate that Vit D₃ exerts cardioprotective effects against I/R cardiac injury by protecting mitochondrial structural and functional integrity and reducing mitophagy.

Autophagy participates in the protection role of 1,25-dihydroxyvitamin D3 in acute myocardial infarction via PI3K/AKT/mTOR pathway

Vitamin D deficiency is associated with acute myocardial infarction (AMI); thus we aimed to explore improvement effects of 1,25-dihydroxyvitamin D3 (VD3) on the AMI and its potential mechanism. AMI models were constructed using male C57/BL6J mice and randomly treated with normal saline or VD3, using sham rats as control. Heart functions, myocardial damage, apoptosis, and inflammation were evaluated. Cardiomyocytes isolated from 3-day-old suckling mice were used for in vitro verification. After VD3 treatment, AMI-induced cardiac dysfunction was reversed with better cardiac function parameters. VD3 treatment reduced inflammatory cell infiltration and myocardial infarction area accompanied by the reduction of inflammatory factors and myocardial infarction markers compared with the AMI group. VD3 treatment obviously alleviated AMI-induced myocardial apoptosis, along with Bcl-2 upregulation and downregulation of caspase-3, caspase-9, and Bax. Both in vivo and in vitro experiments revealed that VD3 enhanced the expression of LC3II and Beclin-1 and decreased soluble p62. Furthermore, VD3 enhanced the AMI-caused inhibition of PI3K, p-AKT, and p-mTOR expression, which was conversely reversed by the addition of 3-methyladenine in vitro. The study highlights the improvement effects of VD3 on cardiac functions. We proposed a potential mechanism that VD3 protects against myocardial damage, inflammation, and apoptosis by promoting autophagy through PI3K/AKT/mTOR pathway.

Autophagy Induction Contributes to the Neuroprotective Impact of Intermittent Fasting on the Acutely Injured Spinal Cord

Spinal cord injury (SCI) is one of the leading causes of neurological disability and death. So far, there is no satisfactory treatment for SCI, because of its complex and ill-defined pathophysiology. Recently, autophagy has been implicated as protective in acute SCI rat models. Here, we investigated the therapeutic value of a dietary intervention, namely, intermittent fasting (IF), on neuronal survival after acute SCI in rats, and its underlying mechanism related to autophagy regulation. We found remarkable improvement in both behavioral performance and neuronal survival at the injured segment of the spinal cord of animals previously subjected to IF. Western blotting revealed a marked decrease in apoptosis-related markers such as cleaved caspase 3 levels and the bax/bcl-2 ratio in the IF group, which suggested an inhibition of the intrinsic apoptosis pathway. In addition, the expression of the autophagy markers LC3-II and beclin 1 was also increased in the IF group compared with ad libitum fed animals. In parallel, IF decreased the levels of the substrate protein of autophagy, p62, indicative of an upregulation of the autophagic processes. Treatment with 3-methyladenine (3-MA), a selective inhibitor of autophagy, reversed the downregulated apoptosis-related markers by IF. Finally, IF could activate the adenosine monophosphate (AMP)-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway and enhance lysosome function by upregulating transcription factor (TF)EB expression. Altogether, the present findings suggest that IF exerts a neuroprotective effect after acute SCI via the upregulation of autophagy, and further points to dietary interventions as a promising combinatorial treatment for SCI.

Supplemental 25-hydroxycholecalciferol Alleviates Inflammation and Cardiac Fibrosis in Hens

Broiler breeder hens with efficient feed conversion rate under restricted feed intake (R-hens) or allowed unlimited access to feed (Ad-hens) progressed with cardiac functional failure and suffered early sudden death. A supplement of 69 μg 25-hydroxycholecalciferol (25-OH-D₃)/kg feed improved heart health and rescued livability in both R- and Ad-hens throughout laying stage (26–60 wks). Improvements occurred through cardiac hypertrophic remodeling, reduced arrhythmias, and pathological cues. Here, we further demonstrated consistently decreased circulating and cardiac IL-6 and IL-1β levels in conjunction with reduced cardiac chemoattraction and leukocyte infiltration by 25-OH-D₃ in Ad-hens and in R-hens at later time points (35 and 47 wks) (p < 0.05). Supplemental 25-OH-D₃ also ameliorated cardiac fibrosis, endoplasmic reticulum (ER) stress, and autophagy, mostly in Ad-hens, as both collagen content and expression of COL3A1, as well as CCAAT box binding enhancer homologous protein (CHOP) and activating transcription factor 6 (ATF6), were consistently decreased, and suppression of microtubule-associated protein 1 light Chain 3 beta (LC3B) and Sequestosome 1 (SQSTM1) was rescued at 35 and 47 wks (p < 0.05). Vitamin D receptor-NF-κB signaling was shown to mediate these beneficial effects. The present results demonstrate that ER stress and autophagic processes along the sequence from inflammation to fibrotic changes contribute to pathological cardiac remodeling and functional compromise by Ad-feed intake. 25-OH-D₃ is an effective anti-inflammatory and anti-fibrotic supplement to ameliorate cardiac pathogenesis in broiler breeder hens.

Biogenesis and functions of circular RNAs and their role in diseases of the female reproductive system

A member of the newly discovered RNA family, circular RNA (circRNA) is considered as the intermediate product of by-product splicing or abnormal RNA splicing. With the development of RNA sequencing, circRNA has recently drawn research interest. CircRNA exhibits stability, species conservatism, and tissue cell specificity. It acts as a miRNA sponge in the circRNA-microRNA (miRNA-mRNA axis, which can regulate gene transcription and protein translation. Studies have confirmed that circRNA is ubiquitous in eukaryotic cells, which play an important role in the regulation of human gene expression and participate in the occurrence and development of various human diseases. CircRNA may be closely related to the occurrence and development of female reproductive system diseases. By analyzing the biological functions and mechanism of circRNA, we find that circRNA has certain development prospects as biomarkers of the female reproductive system diseases. The production and degradation of circRNA, biological functions, and their association with the occurrence of diseases of female reproductive system are reviewed in this article.

TXNIP/Redd1 signalling and excessive autophagy: a novel mechanism of myocardial ischaemia/reperfusion injury in mice

AIMS

Either insufficient or excessive autophagy causes cellular death and contributes to myocardial ischaemia/reperfusion (I/R) injury. However, mechanisms controlling the 'right-level' of autophagy in the heart remains unidentified. Thioredoxin-interacting protein (TXNIP) is a pro-oxidative molecule knowing to contribute to I/R injury. However, whether and how TXNIP may further inhibit suppressed autophagy or promote excessive cardiac autophagy in I/R heart has not been previously investigated.

METHODS AND RESULTS

Wild type or gene-manipulated adult male mice were subjected to myocardial I/R. TXNIP was increased in myocardium during I/R. Cardiac-specific TXNIP overexpression increased cardiomyocytes apoptosis and cardiac dysfunction, whereas cardiac-specific TXNIP knock-out significantly mitigated I/R-induced apoptosis and improved cardiac function. Importantly, TXNIP overexpression significantly promoted cardiac autophagy and TXNIP knock-out significantly inhibited cardiac autophagy. In vitro studies demonstrated that TXNIP increased autophagosome formation but inhibited autophagosome clearance during myocardial reperfusion. Atg5 siRNA significantly decreased hypoxia/reoxygenation induced apoptosis in cardiomyocytes with TXNIP overexpression. Mechanistically, TXNIP suppressed autophagosome clearance via increasing reactive oxygen species (ROS) level. However, TXNIP-increased autophagosome formation was not mediated by ROS as a ROS scavenger failed to block increased autophagosome formation in TXNIP overexpression heart. Finally, TXNIP directly interacted and stabilized Redd1 (an autophagy regulator), resulting in mTOR inhibition and autophagy activation. Redd1 knock-down significantly reduced autophagy formation and ameliorated I/R injury in TXNIP overexpression hearts.

CONCLUSIONS

Our results demonstrated that increased TXNIP-Redd1 expression is a novel signalling pathway that contributes to I/R injury by exaggerating excessive autophagy during reperfusion. These observations advance our understanding of the mechanisms of myocardial I/R injury.

Implications of Oxidative Stress and Potential Role of Mitochondrial Dysfunction in COVID-19: Therapeutic Effects of Vitamin D

Due to its high degree of contagiousness and like almost no other virus, SARS-CoV-2 has put the health of the world population on alert. COVID-19 can provoke an acute inflammatory process and uncontrolled oxidative stress, which predisposes one to respiratory syndrome, and in the worst case, death. Recent evidence suggests the mechanistic role of mitochondria and vitamin D in the development of COVID-19. Indeed, mitochondrial dynamics contribute to the maintenance of cellular homeostasis, and its uncoupling involves pathological situations. SARS-CoV-2 infection is associated with altered mitochondrial dynamics with consequent oxidative stress, pro-inflammatory state, cytokine production, and cell death. Furthermore, vitamin D deficiency seems to be associated with increased COVID-19 risk. In contrast, vitamin D can normalize mitochondrial dynamics, which would improve oxidative stress, pro-inflammatory state, and cytokine production. Furthermore, vitamin D reduces renin–angiotensin–aldosterone system activation and, consequently, decreases ROS generation and improves the prognosis of SARS-CoV-2 infection. Thus, the purpose of this review is to deepen the knowledge about the role of mitochondria and vitamin D directly involved in the regulation of oxidative stress and the inflammatory state in SARS-CoV-2 infection. As future prospects, evidence suggests enhancing the vitamin D levels of the world population, especially of those individuals with additional risk factors that predispose to the lethal consequences of SARS-CoV-2 infection.

Circular RNA as a potential diagnostic and/or therapeutic target for endometriosis

Endometriosis is a pathology form of endometrium that behaves in a similar way to malignancies, such as invasion and resistance to apoptosis. Circular RNAs (CircRNAs) are a class of noncoding RNAs that have several biological functions including, miRNA sponging, sequestering of proteins, enhancing parental gene expression and translation resulting in polypeptides. In this review, we highlighted the roles of circRNAs as potential diagnostic and therapeutic biomarkers in endometriosis. Moreover, we summarized the roles of circRNAs in the pathogenesis of endometriosis via different signaling pathways, such as the miRNA network and apoptosis.