The role of sex differences in autophagy in the heart during coxsackievirus B3-induced myocarditis

Jingfang Granule mitigates Coxsackievirus B3-induced myocardial damage by modulating mucolipin 1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Jingfang Granules (JFG) originate from the traditional herbal formula Jingfang Baidu powder. It has the effects of inducing sweating and dispelling wind. It is a classic medication used for treating external pathogenic factors and viral diseases. However, the therapeutic mechanism of JFG for viral myocarditis needs further clarification.

AIM OF THE STUDY

This study aimed to explore the therapeutic efficacy of JFG on coxsackievirus B3-induced viral myocarditis (VMC), along with the elucidation of its underlying mechanisms.

MATERIALS AND METHODS

C57 BL/6JNifdc mice were divided randomly into several groups: control, model, Jingfang Granule groups (0.23, 0.46, and 0.69 g/20g, respectively), and a positive group (oseltamivir, 19.33 mg/kg). Following the establishment of the VMC model, the mice underwent an 8 -week treatment regimen. Pathological alterations in cardiac tissues and inflammatory protein expression were monitored. Differential gene analysis was conducted utilizing transcriptomic techniques. The differential gene mucolipin 1 (Mcoln1) was knocked down by transfection with siRNA in H9C2 cell, and investigative techniques such as immunoblotting, qRT-PCR, immunofluorescence, JC-1 staining, reactive oxygen species (ROS) detection, and mitochondrial stress testing were employed to examine its mechanism of action.

RESULTS

JFG significantly mitigates the pathological damage observed in the cardiac tissues of CVB3-induced VMC mice and attenuates the expression of inflammatory genes. Subsequently, differentially expressed genes are identified through transcriptomic analysis and validated via PCR. Among these, the upregulation of Mcoln1 promotes autophagy, facilitating the clearance of damaged mitochondria and excessive ROS. This has been substantiated through in vitro experiments. Excessive ROS precipitates a reduction in mitochondrial membrane potential, instigating cell apoptosis. In accordance with TUNEL staining results, JFG acts to inhibit cell apoptosis. To ascertain whether Mcoln1 is a crucial target for JFG in treating VMC, Mcoln1 was suppressed in H9C2 cells. The suppression of Mcoln1 hinders the elevation in autophagy levels post-JFG treatment, obstructs the enhancement of mitochondrial function, and impedes the clearance of ROS. Furthermore, the inhibitory effect of JFG on cell apoptosis is attenuated.

CONCLUSION

The research findings indicate that JFG has a protective effect on CVB3-induced H9C2 cell injury. JFG may exert its effects in VMC treatment by enhancing autophagy to suppress cell apoptosis through the mitochondrial pathway, thereby counteracting cell damage.

LAMP2A, and other chaperone-mediated autophagy related proteins, do not decline with age in genetically heterogeneous UM-HET3 mice

Chaperone-mediated autophagy (CMA) selectively degrades proteins that are crucial for glycolysis, fatty acid metabolism, and the progression of several age-associated diseases. Several previous studies, each of which evaluated males of a single inbred mouse or rat strain, have reported that CMA declines with age in many tissues, attributed to an age-related loss of LAMP2A, the primary and indispensable component of the CMA translocation complex. This has led to a paradigm in the field of CMA research, stating that the age-associated decline in LAMP2A in turn decreases CMA, contributing to the pathogenesis of late-life disease. We assessed LAMP2A levels and CMA substrate uptake in both sexes of the genetically heterogeneous UM-HET3 mouse stock, which is the current global standard for the evaluation of anti-aging interventions. We found no evidence for age-related changes in LAMP2A levels, CMA substrate uptake, or whole liver levels of CMA degradation targets, despite identifying sex differences in CMA.

Cardiovascular Disease in Women: What the Radiologist Needs to Know

BACKGROUND

 Sex-specific disparities are well documented for cardiovascular disease (CVD). There are differences in physiology and pathophysiology, pain perception, spectrum of disease, risk, therapeutic aspects, prognosis, and outcome. CVD represents a broad spectrum of disorders. This review focuses on cardiovascular and cardiac pathology.

METHOD

 This review summarizes the current state of the literature on cardiovascular disease in women from a radiological viewpoint. It aims to provide a deeper understanding of these differences and thereby alerts the reader to the potential of CT and MRI for diagnosing CVD in women. Special attention is paid to disparities in the underlying physiological and pathophysiological processes, clinical presentation, and the quality of care to provide a deep understanding of the topic. Cardiovascular and cardiac pathologies with a sex-specific pattern of disease are presented and typical CT and MRI findings are arranged and illustrated with imaging findings.

RESULTS AND CONCLUSION

 Sex-specific differences are not only sex hormonal in nature but are rooted in the epigenome and encompass a multitude of physiological systems. In fact, cardiovascular disease shows sex-specific characteristics spanning from incidence to clinical presentation, course of disease, and prognosis. This is of significance regarding pretest probabilities, the power of tests, imaging strategies, and interpretation of imaging results. Key sex-specific issues encompass obstructive and non-obstructive coronary artery disease (CAD), microvascular angina, myocardial infarction with non-obstructive CAD, and coronary artery dissection. Sex-specific patterns are also noted in myocardial disease and heart failure such as pregnancy-related heart disease, Takotsubo syndrome, and anthracycline-induced cardiotoxicity.

KEY POINTS

  · Cardiovascular diseases have sex-specific characteristics.. · Imaging strategies and interpretation of imaging results should be adjusted for women.. · Imaging helps in the improvement of the sex-specific management of cardiovascular disease..

A maternal low-protein diet during gestation induces hepatic autophagy-related gene expression in a sex-specific manner in Sprague-Dawley rats

This study investigates the mechanism by which maternal protein restriction induces hepatic autophagy-related gene expression in the offspring of rats. Pregnant Sprague-Dawley rats were fed either a control diet (C, 18 % energy from protein) or a low-protein diet (LP, 8·5 % energy from protein) during gestation, followed by the control diet during lactation and post-weaning. Liver tissue was collected from the offspring at postnatal day 38 and divided into four groups according to sex and maternal diet (F-C, F-LP, M-C and M-LP) for further analysis. Autophagy-related mRNA and protein levels were determined by real-time PCR and Western blotting, respectively. In addition, chromatin immunoprecipitation (ChIP) was performed to investigate the interactions between transcription factors and autophagy-related genes. Protein levels of p- eukaryotic translation initiation factor 2a and activating transcription factor 4 (ATF4) were increased only in the female offspring born to dams fed the LP diet. Correlatively, the mRNA expression of hepatic autophagy-related genes including Map1lc3b, P62/Sqstm1, Becn1, Atg3, Atg7 and Atg10 was significantly greater in the F-LP group than in the F-C group. Furthermore, ChIP results showed greater ATF4 and C/EBP homology protein (CHOP) binding at the regions of a set of autophagy-related genes in the F-LP group than in the F-C group. Our data demonstrated that a maternal LP diet transcriptionally programmed hepatic autophagy-related gene expression only in female rat offspring. This transcriptional programme involved the activation of the eIF2α/ATF4 pathway and intricate regulation by transcription factors ATF4 and CHOP.

A new miRNA-Modified coxsackievirus B3 inhibits triple negative breast cancer growth with improved safety profile in immunocompetent mice

Coxsackievirus B3 (CVB3) displays great oncolytic activity against various cancer cells. Previously, we demonstrated that adding targeting sequences (TS) of miR-145/143, which are downregulated in cancer compared with normal cells, into CVB3 genome drastically attenuates tissue toxicity, while retaining its oncolytic activity towards lung tumor. Here we extended to assess miR-modified CVB3 in breast cancer therapy. We generated a new miRNA-CVB3 by inserting TS of muscle-specific miR-1 and pancreas-selective miR-216 into the above miR-145/143-modified CVB3. We found that this newly established CVB3 (termed miR-CVB3-1.1) is safe without triggering noticeable pathogenesis when applied to immunocompetent mice. In vitro studies revealed that miR-CVB3-1.1 can infect and lyse a wide range of breast cancer cells. Animal experiments using a syngeneic breast cancer mouse model showed that intratumoral inoculation of miR-CVB3-1.1 significantly suppresses tumor growth and metastasis, associated with productive viral growth and enhanced immune cell infiltration in the tumor microenvironment. Moreover, we observed substantially reduced toxicity and prolonged survival in mice treated with miR-CVB3-1.1 compared with wild-type CVB3. Together, our results support miR-CVB3-1.1 as a promising candidate, which can be further evaluated for clinical treatment of breast cancer.

Burden of Cardiomyopathic Genetic Variation in Lethal Pediatric Myocarditis

BACKGROUND

Acute myocarditis (AM) is a well-known cause of sudden death and heart failure, often caused by prevalent viruses. We previously showed that some pediatric AM correlates with putatively damaging variants in genes related to cardiomyocyte structure and function. We sought to evaluate whether deleterious cardiomyopathic variants were enriched among fatal pediatric AM cases in New York City compared with ancestry-matched controls.

METHODS

Twenty-four children (aged 3 weeks to 20 years) with death due to AM were identified through autopsy records; histologies were reviewed to confirm that all cases met Dallas criteria for AM and targeted panel sequencing of 57 cardiomyopathic genes was performed. Controls without cardiovascular disease were identified from a pediatric database and matched by genetic ancestry to cases using principal components from exome sequencing. Rates of putative deleterious variations (DV) were compared between cases and controls. Where available, AM tissues underwent viral analysis by polymerase chain reaction.

RESULTS

DV were identified in 4 of 24 AM cases (16.7%), compared with 2 of 96 age and ancestry-matched controls (2.1%, P=0.014). Viral causes were proven for 6 of 8 AM cases (75%), including the one DV+ case where tissue was available for testing. DV+ cases were more likely to be female, have no evidence of chronic inflammation, and associate with sudden cardiac death than DV- cases.

CONCLUSIONS

Deleterious variants in genes related to cardiomyocyte integrity are more common in children with fatal AM than controls, likely conferring susceptibility. Additionally, genetically mediated AM may progress more rapidly and be more severe.

Intratonsillar detection of 27 distinct viruses: A cross-sectional study

Palatine tonsils have been observed to harbor several distinct respiratory and herpesviruses in separate studies. In this study, the presence of these viruses in palatine tonsils was comprehensively studied in both children and adults. A cross-sectional analysis of 181 patients (median age 22 years; range, 2.6-66) operated for a benign tonsillar disease was conducted. Real-time polymerase chain reaction was performed to detect 27 distinct viruses in all: eight human herpesviruses, 16 respiratory viruses, parvo B19, and polyoma BK/JC viruses. Clinical characteristics of the patients and underlying conditions were evaluated. In total, 92% of patients had virus detected in tonsils (Epstein-Barr virus 72%, human herpesvirus 7, and 6B 54% and 16%, respectively, enterovirus 18%, parvovirus B19 7% and the rest <4%). No herpes simplex virus 2, varicella zoster virus, polyoma JC virus, parainfluenza-, metapneumo-, or coronaviruses were found. Enterovirus was more common in children and was frequently observed in the presence of HHV6B. None of the viruses showed a positive association to the tonsillar disease. Respiratory symptoms were not associated with the prevalence of viruses. This study comprehensively reports a cross-sectional view of intratonsillar virus infections in elective tonsillectomy patients in a wide age range cohort. Tonsils are a major virus reservoir for distinct herpes and respiratory viruses without a positive association with tonsillar disease or respiratory symptoms.

Aging lowers PEX5 levels in cortical neurons in male and female mouse brains

Peroxisomes exist in nearly every cell, oxidizing fats, synthesizing lipids and maintaining redox balance. As the brain ages, multiple pathways are negatively affected, but it is currently unknown if peroxisomal proteins are affected by aging in the brain. While recent studies have investigated a PEX5 homolog in aging C. elegans models and found that it is reduced in aging, it is unclear if PEX5, a mammalian peroxisomal protein that plays a role in peroxisomal homeostasis and degradation, is affected in the aging brain. To answer this question, we first determined the amount of PEX5, in brain homogenates from young (3 months) and aged (26 through 32+ months of age) wild-type mice of both sexes. PEX5 protein was decreased in aged male brains, but this reduction was not significant in female brains. RNAScope and real-time qPCR analyses showed that Pex5 mRNA was also reduced in aged male brain cortices, but not in females. Immunohistochemistry assays of cortical neurons in young and aged male brains showed that the amount of neuronal PEX5 was reduced in aged male brains. Cortical neurons in aged female mice also had reduced PEX5 levels in comparison to younger female mice. In conclusion, total PEX5 levels and Pex5 gene expression both decrease with age in male brains, and neuronal PEX5 levels lower in an age-dependent manner in the cortices of animals of both sexes.

Sex differences underlying preexisting cardiovascular disease and cardiovascular injury in COVID-19

The novel 2019 coronavirus disease (COVID-19), resulting from severe acute respiratory syndrome coronarvirus-2 (SARS-CoV-2) infection, typically leads to respiratory failure in severe cases; however, cardiovascular injury is reported to contribute to a substantial proportion of COVID-19 deaths. Preexisting cardiovascular disease (CVD) is among the most common risk factors for hospitalization and death in COVID-19 patients, and the pathogenic mechanisms of COVID-19 disease progression itself may promote the development of cardiovascular injury, increasing risk of in-hospital death. Sex differences in COVID-19 are becoming more apparent as mounting data indicate that males seem to be disproportionately at risk of severe COVID-19 outcome due to preexisting CVD and COVID-19-related cardiovascular injury. In this review, we will provide a basic science perspective on current clinical observations in this rapidly evolving field and discuss the interplay sex differences, preexisting CVD and COVID-19-related cardiac injury.

Luteolin inhibits CVB3 replication through inhibiting inflammation

Coxsackievirus B3 (CVB3) infection causes many inflammation-related diseases, such as viral myocarditis and aseptic meningitis. However, no vaccines or drugs have been approved for prevention or therapy of CVB3-induced diseases. In this study, luteolin (3,4,5,7-tetrahydroxyflavone) had been found that could dose-dependently reduce the production of viral progeny and synthesis of CVB3 RNA and protein. The luteolin-mediated inhibition of CVB3 was found to be mechanistically possible, at least in part, through depressing the phosphorylation of p38 MAPK and JNK MAPK, and inhibiting NF-κB nuclear translocation and subsequently attenuated the expression of inflammatory cytokines in CVB3-infected cells. Luteolin may be a potential agent or supplement against CVB3 infection by inhibiting inflammation.

Sex differences in autophagy-mediated diseases: toward precision medicine

Nearly all diseases in humans, to a certain extent, exhibit sex differences, including differences in the onset, progression, prevention, therapy, and prognosis of diseases. Accumulating evidence shows that macroautophagy/autophagy, as a mechanism for development, differentiation, survival, and homeostasis, is involved in numerous aspects of sex differences in diseases such as cancer, neurodegeneration, and cardiovascular diseases. Advances in our knowledge regarding sex differences in autophagy-mediated diseases have enabled an understanding of their roles in human diseases, although the underlying molecular mechanisms of sex differences in autophagy remain largely unexplored. In this review, we discuss current advances in our insight into the biology of sex differences in autophagy and disease, information that will facilitate precision medicine.Abbreviations: AD: Azheimer disease; AMBRA1: autophagy and beclin 1 regulator 1; APP: amyloid beta precursor protein; AR: androgen receptor; AMPK: AMP-activated protein kinase; ATG: autophagy related; ATP6AP2: ATPase H+ transporting accessory protein 2; BCL2L1: BCL2 like 1; BECN1: beclin 1; CTSD: cathepsin D; CYP19A1: cytochrome P450 family 19 subfamily A member 1; DSD: disorders of sex development; eALDI: enhancer alternate long-distance initiator; ESR1: estrogen receptor 1; ESR2: estrogen receptor 2; FYCO1: FYVE and coiled-coil domain autophagy adaptor 1; GABARAP: GABA type A receptor-associated protein; GLA: galactosidase alpha; GTEx: genotype-tissue expression; HDAC6: histone deacetylase 6; I-R: ischemia-reperfusion; LAMP2: lysosomal associated membrane protein 2; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; m6A: N6-methyladenosine; MYBL2: MYB proto-oncogene like 2; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PSEN1: presenilin 1; PSEN2: presenilin 2; RAB9A, RAB9A: member RAS oncogene family; RAB9B, RAB9B: member RAS oncogene family; RAB40AL: RAB40A like; SF1: splicing factor 1; SOX9: SRY-box transcription factor 9; SRY: sex determining region Y; TFEB: transcription factor EB; ULK1: unc-51 like autophagy activating kinase 1; UVRAG: UV radiation resistance associated; VDAC2: voltage dependent anion channel 2; WDR45: WD repeat domain 45; XPDS: X-linked parkinsonism and spasticity; YTHDF2: YTH N6-methyladenosine RNA binding protein 2.

Sex differences in inflammation, redox biology, mitochondria and autoimmunity

Autoimmune diseases are characterized by circulating antibodies and immune complexes directed against self-tissues that result in both systemic and organ-specific inflammation and pathology. Most autoimmune diseases occur more often in women than men. One exception is myocarditis, which is an inflammation of the myocardium that is typically caused by viral infections. Sex differences in the immune response and the role of the sex hormones estrogen and testosterone are well established based on animal models of autoimmune viral myocarditis as well as in mitochondrial function leading to reactive oxygen species production. RNA viruses like coxsackievirus B3, the primary cause of myocarditis in the US, activate the inflammasome through mitochondrial antiviral signaling protein located on the mitochondrial outer membrane. Toll-like receptor 4 and the inflammasome are the primary signaling pathways that increase inflammation during myocarditis, which is increased by testosterone. This review describes what is known about sex differences in inflammation, redox biology and mitochondrial function in the male-dominant autoimmune disease myocarditis and highlights gaps in the literature and future directions.

Deletion of Nrip1 Extends Female Mice Longevity, Increases Autophagy, and Delays Cell Senescence

Using age of female sexual maturation as a biomarker, we previously identified nuclear receptor interacting protein 1 (Nrip1) as a candidate gene that may regulate aging and longevity. In the current report, we found that the deletion of Nrip1 can significantly extend longevity of female mice (log-rank test, p = .0004). We also found that Nrip1 expression is altered differently in various tissues during aging and under diet restriction. Remarkably, Nrip1 expression is elevated with aging in visceral white adipose tissue (WAT), but significantly reduced after 4 months of diet restriction. However, in gastrocnemius muscle, Nrip1 expression is significantly upregulated after the diet restriction. In mouse embryonic fibroblasts, we found that the deletion of Nrip1 can suppress fibroblast proliferation, enhance autophagy under normal culture or amino acid starvation conditions, as well as delay oxidative and replicative senescence. Importantly, in WAT of old animals, the deletion of the Nrip could significantly upregulate autophagy and reduce the number of senescent cells. These results suggest that deleting Nrip1 can extend female longevity, but tissue-specific deletion may have varying effects on health span. The deletion of Nrip1 in WAT may delay senescence in WAT and extend health span.

Role of estrogen and its receptors mediated-autophagy in cell fate and human diseases

Studies have shown that morbidity of several diseases varies between males and females. This difference likely arises due to sex-related hormones. Estrogen, a primary female sex steroid hormone, plays a critical role in mediating many of the physiological functions like growth, differentiation, metabolism, and cell death. Recently, it has been demonstrated that estrogen mediates autophagy through its receptors (ERs) namely ERα, ERβ, and G-protein coupled estrogen receptor (GPER). However, the specific role of estrogen and its receptors mediated-autophagy in cell fate and human diseases such as cancers, cardiovascular disease and nervous system disease remains unclear. In this review, we comprehensively summarize the complex role of estrogen and its receptors-mediated autophagy in different cell lines and human diseases. In addition, we further discuss the key signaling molecules governing the role of ERs in autophagy. This review will serve as the basis for a proposed model of autophagy constituting a new frontier in estrogen-related human diseases. Here, we discuss the dual role of ERα in classical and non-classical autophagy through B-cell lymphoma 2 (BCL2)-associated athanogene 3 (BAG3). Next, we review the role of ERβ in pro-survival pathways through the promotion of autophagy under stress conditions. We further discuss activation of GPER via estrogen often mediates autophagy or mitophagy suppression, respectively. In summary, we believe that understanding the relationship between estrogen and its receptors mediated-autophagy on cell fate and human diseases will provide insightful knowledge for future therapeutic implications.

ADAR1p150 Forms a Complex with Dicer to Promote miRNA-222 Activity and Regulate PTEN Expression in CVB3-Induced Viral Myocarditis

Adenosine deaminases acting on RNA (ADAR) are enzymes that regulate RNA metabolism through post-transcriptional mechanisms. ADAR1 is involved in a variety of pathological conditions including inflammation, cancer, and the host defense against viral infections. However, the role of ADAR1p150 in vascular disease remains unclear. In this study, we examined the expression of ADAR1p150 and its role in viral myocarditis (VMC) in a mouse model. VMC mouse cardiomyocytes showed significantly higher expression of ADAR1p150 compared to the control samples. Coimmunoprecipitation verified that ADAR1p150 forms a complex with Dicer in VMC. miRNA-222, which is involved in many cardiac diseases, is highly expressed in cardiomyocytes in VMC. In addition, the expression of miRNA-222 was promoted by ADAR1p150/Dicer. Among the target genes of miRNA-222, the expression of phosphatase-and-tensin (PTEN) protein was significantly reduced in VMC. By using a bioinformatics tool, we found a potential binding site of miRNA-222 on the PTEN gene’s 3′-UTR, suggesting that miRNA-222 might play a regulatory role. In cultured cells, miR-222 suppressed PTEN expression. Our findings suggest that ADAR1p150 plays a key role in complexing with Dicer and promoting the expression of miRNA-222, the latter of which suppresses the expression of the target gene PTEN during VMC. Our work reveals a previously unknown role of ADAR1p150 in gene expression in VMC.

Sexual dimorphism in activation of placental autophagy in obese women with evidence for fetal programming from a placenta-specific mouse model

The incidence of maternal obesity and its co-morbidities (diabetes, cardiovascular disease) continues to increase at an alarming rate, with major public health implications. In utero exposure to maternal obesity has been associated with development of cardiovascular and metabolic diseases in the offspring as a result of developmental programming. The placenta regulates maternal-fetal metabolism and shows significant changes in its function with maternal obesity. Autophagy is a cell-survival process, which is responsible for the degradation of damaged organelles and misfolded proteins. Here we show an activation of autophagosomal formation and autophagosome-lysosome fusion in placentas of males but not females from overweight (OW) and obese (OB) women vs. normal weight (NW) women. However, total autophagic activity in these placentas appeared to be decreased as it showed an increase in SQSTM1/p62 and a decrease in lysosomal biogenesis. A mouse model with a targeted deletion of the essential autophagy gene Atg7 in placental tissue showed significant placental abnormalities comparable to those seen in human placenta with maternal obesity. These included a decrease in expression of mitochondrial genes and antioxidants, and decreased lysosomal biogenesis. Strikingly, the knockout mice were developmentally programmed as they showed an increased sensitivity to high-fat diet-induced obesity, hyperglycemia, hyperinsulinemia, increased adiposity, and cardiac remodeling. In summary, our results indicate a sexual dimorphism in placental autophagy in response to maternal obesity. We also show that autophagy plays an important role in placental function and that inhibition of placental autophagy programs the offspring to obesity, and to metabolic and cardiovascular diseases.

Monocytic myeloid-derived suppressor cells from females, but not males, alleviate CVB3-induced myocarditis by increasing regulatory and CD4(+)IL-10(+) T cells

Coxsackievirus group B type 3 (CVB3) is a common etiologic agent of viral myocarditis and often causes sexually dimorphic myocarditis with increased incidence and mortality in male. So far, the underlying mechanism for the high male prevalence is not well elucidated. In this study, we deciphered the role of myeloid-derived suppressor cells (MDSCs) in the gender bias in murine CVB3-induced myocarditis by comparing their frequencies, subsets as well as immune suppressive functions. We found that much more myocardial MDSCs were enriched in infected females than males, with dramatically higher percentage ratio of CD11b⁺Ly6G-Ly6C^high monocytic subset (M-MDSCs) to CD11b⁺Ly6G⁺Ly6C^low granulocytic subset (G-MDSCs). Interestingly, more potent suppression on T cell proliferation was also evidenced in female-derived M-MDSCs. Consistently, adoptive transfer of female- but not male-derived M-MDSCs efficiently alleviated CVB3-induced myocarditis in male recipient mice, and this protection could be ascribed to the increased induction of regulatory and CD4⁺IL-10⁺ T cells. Our study suggested that myocardial MDSCs were distinctively induced not only in quantities but also in phenotypes and immune suppressive functions in CVB3-infected males and females; and female-derived more suppressive M-MDSCs contributed to their insensitivity to CVB3-induced myocarditis.

Endolysosomal two-pore channels regulate autophagy in cardiomyocytes

KEY POINTS

Two-pore channels (TPCs) were identified as a novel family of endolysosome-targeted calcium release channels gated by nicotinic acid adenine dinucleotide phosphate, as also as intracellular Na(+) channels able to control endolysosomal fusion, a key process in autophagic flux. Autophagy, an evolutionarily ancient response to cellular stress, has been implicated in the pathogenesis of a wide range of cardiovascular pathologies, including heart failure. We report direct evidence indicating that TPCs are involved in regulating autophagy in cardiomyocytes, and that TPC knockout mice show alterations in the cardiac lysosomal system. TPC downregulation implies a decrease in the viability of cardiomyocytes under starvation conditions. In cardiac tissues from both humans and rats, TPC transcripts and protein levels were higher in females than in males, and correlated negatively with markers of autophagy. We conclude that the endolysosomal channels TPC1 and TPC2 are essential for appropriate basal and induced autophagic flux in cardiomyocytes, and also that they are differentially expressed in male and female hearts.

ABSTRACT

Autophagy participates in physiological and pathological remodelling of the heart. The endolysosomal two-pore channels (TPCs), TPC1 and TPC2, have been implicated in the regulation of autophagy. The present study aimed to investigate the role of TPC1 and TPC2 in basal and induced cardiac autophagic activity. In cultured cardiomyocytes, starvation induced a significant increase in TPC1 and TPC2 transcripts and protein levels that paralleled the increase in autophagy identified by increased LC3-II and decreased p62 levels. Small interfering RNA depletion of TPC2 alone or together with TPC1 increased both LC3II and p62 levels under basal conditions and in response to serum starvation, suggesting that, under conditions of severe energy depletion (serum plus glucose starvation), changes in the autophagic flux (as assessed by use of bafilomycin A1) occurred either when TPC1 or TPC2 were downregulated. The knockdown of TPCs diminished cardiomyocyte viability under starvation and simulated ischaemia. Electron micrographs of hearts from TPC1/2 double knockout mice showed that cardiomyocytes contained large numbers of immature lysosomes with diameters significantly smaller than those of wild-type mice. In cardiac tissues from humans and rats, TPC1 and TPC2 transcripts and protein levels were higher in females than in males. Furthermore, transcript levels of TPCs correlated negatively with p62 levels in heart tissues. TPC1 and TPC2 are essential for appropriate basal and induced autophagic flux in cardiomyocytes (i.e. there is a negative effect on cell viability under stress conditions in their absence) and they are differentially expressed in male and female human and murine hearts, where they correlate with markers of autophagy.

Neurotropic Enterovirus Infections in the Central Nervous System

Enteroviruses are a group of positive-sense single stranded viruses that belong to the Picornaviridae family. Most enteroviruses infect humans from the gastrointestinal tract and cause mild symptoms. However, several enteroviruses can invade the central nervous system (CNS) and result in various neurological symptoms that are correlated to mortality associated with enteroviral infections. In recent years, large outbreaks of enteroviruses occurred worldwide. Therefore, these neurotropic enteroviruses have been deemed as re-emerging pathogens. Although these viruses are becoming large threats to public health, our understanding of these viruses, especially for non-polio enteroviruses, is limited. In this article, we review recent advances in the trafficking of these pathogens from the peripheral to the central nervous system, compare their cell tropism, and discuss the effects of viral infections in their host neuronal cells.

Panax Notoginseng Saponins Ameliorates Coxsackievirus B3-Induced Myocarditis by Activating the Cystathionine-γ-Lyase/Hydrogen Sulfide Pathway

This study is to determine the therapeutic effects of Panax notoginseng saponins (PNSs) on coxsackievirus B3 (CVB3)-induced myocarditis, and whether cystathionine-γ-lyase (CSE)/hydrogen sulfide (H2S) pathway is involved. Mouse model of myocarditis was induced by CVB3 infection, and the mice were subjected to vehicle (saline) or drug treatments (sodium bisulfide (NaHS), propargylglycine (PAG), or PNSs). The results showed that there were inflammatory cell infiltrations, interstitial edemas, and elevated inflammatory cytokines, in CVB3-induced myocarditis. PAG administration increased, whereas NaHS treatment decreased the severity of the myocarditis. PNS treatment dramatically alleviated these myocardial injuries and decreased the viral messenger RNA (mRNA) expression by the enhanced expression of CSE/H2S pathway. Moreover, the therapeutic effects of PNSs on myocarditis were stronger than those of NaHS. Finally, the effect of PNSs on CSE/H2S pathway and cardiac cell protection were verified in cultured cardiac cells. PNSs may be a promising medication for viral myocarditis therapy.

Mitochondrial maintenance failure in aging and role of sexual dimorphism

Gene expression changes during aging are partly conserved across species, and suggest that oxidative stress, inflammation and proteotoxicity result from mitochondrial malfunction and abnormal mitochondrial-nuclear signaling. Mitochondrial maintenance failure may result from trade-offs between mitochondrial turnover versus growth and reproduction, sexual antagonistic pleiotropy and genetic conflicts resulting from uni-parental mitochondrial transmission, as well as mitochondrial and nuclear mutations and loss of epigenetic regulation. Aging phenotypes and interventions are often sex-specific, indicating that both male and female sexual differentiation promote mitochondrial failure and aging. Studies in mammals and invertebrates implicate autophagy, apoptosis, AKT, PARP, p53 and FOXO in mediating sex-specific differences in stress resistance and aging. The data support a model where the genes Sxl in Drosophila, sdc-2 in Caenorhabditis elegans, and Xist in mammals regulate mitochondrial maintenance across generations and in aging. Several interventions that increase life span cause a mitochondrial unfolded protein response (UPRmt), and UPRmt is also observed during normal aging, indicating hormesis. The UPRmt may increase life span by stimulating mitochondrial turnover through autophagy, and/or by inhibiting the production of hormones and toxic metabolites. The data suggest that metazoan life span interventions may act through a common hormesis mechanism involving liver UPRmt, mitochondrial maintenance and sexual differentiation.

Antiviral and myocyte protective effects of IL-28A in coxsackievirus B3-induced myocarditis

OBJECTIVE

This study aimed to investigate whether interleukin-28A (IL-28A) plays a role in murine myocarditis induced by coxsackievirus B3 (CVB3), and to explore its possible mechanism involved.

METHODS

Male BALB/c mice both infected and not infected by CVB3 were randomly divided into four groups (n=40), untreated or treated with different doses of IL-28A for 4 days, and then sacrificed on days 4 and 7 post-infection. The heart samples were collected for histopathologic examination. Cardiac viral load was determined by a plaque assay. Additionally, immunoblot analysis, TUNEL assay, and immunohistochemistry were performed to examine the expression of signal transducer, activator of transcription 1 and 2 (STAT1 and STAT2), CVB3-induced apoptosis and the expression of Bcl-2, BAX and Caspase-3.

RESULTS

Compared to uninfected mice, the CVB3 infected mice exhibited higher mortality rate (p<0.001), apparent inflammation and myocardial lesion (p<0.01), and higher cardiac viral load (p<0.01). After CVB3 infection, IL-28A treated mice presented no death (p<0.001), reduced inflammation and myocardial lesion (p<0.01), and lower viral load (p<0.01) compared to untreated mice. Besides, treatment with IL-28A markedly increased the expressions of STAT1 and STAT2, and inhibited CVB3-induced apoptosis in myocardial cells with increased ratio of Bcl-2/BAX.

CONCLUSION

The antiviral and myocyte protective effects of IL-28A in CVB3-induced myocarditis are regulated by STAT1 and STAT2.

Unresolved issues in theories of autoimmune disease using myocarditis as a framework

Many theories of autoimmune disease have been proposed since the discovery that the immune system can attack the body. These theories include the hidden or cryptic antigen theory, modified antigen theory, T cell bypass, T cell-B cell mismatch, epitope spread or drift, the bystander effect, molecular mimicry, anti-idiotype theory, antigenic complementarity, and dual-affinity T cell receptors. We critically review these theories and relevant mathematical models as they apply to autoimmune myocarditis. All theories share the common assumption that autoimmune diseases are triggered by environmental factors such as infections or chemical exposure. Most, but not all, theories and mathematical models are unifactorial assuming single-agent causation of disease. Experimental and clinical evidence and mathematical models exist to support some aspects of most theories, but evidence/models that support one theory almost invariably supports other theories as well. More importantly, every theory (and every model) lacks the ability to account for some key autoimmune disease phenomena such as the fundamental roles of innate immunity, sex differences in disease susceptibility, the necessity for adjuvants in experimental animal models, and the often paradoxical effect of exposure timing and dose on disease induction. We argue that a more comprehensive and integrated theory of autoimmunity associated with new mathematical models is needed and suggest specific experimental and clinical tests for each major theory that might help to clarify how they relate to clinical disease and reveal how theories are related.