OBJECTIVETo investigate the myocardial protective effect of L-carnitine in children with hand, foot and mouth disease (HFMD) caused by Coxsackie A16 virus and possible mechanisms.

METHODSA total of 60 HFMD children with abnormal myocardial enzyme after Coxsackie A16 virus infection were enrolled and randomly divided into L-carnitine group and fructose-1,6-diphosphate group (fructose group), with 30 children in each group. The two groups were given L-carnitine or fructose diphosphate in addition to antiviral and heat clearance treatment. Another 30 healthy children who underwent physical examination were enrolled as control group. The changes in myocardial zymogram, malondialdehyde (MDA), superoxide dismutase (SOD), and apoptosis factors sFas and sFasL after treatment were compared between groups.

RESULTSThere was no significant difference in treatment response between the L-carnitine group and the fructose group (P>0.05). One child in the fructose group progressed to critical HFMD, which was not observed in the L-carnitine group. Before treatment, the L-carnitine group and the fructose group had significantly higher indices of myocardial zymogram and levels of MDA, sFas, and sFasL and a significantly lower level of SOD than the control group (P<0.05), while there were no significant differences in these indices between the L-carnitine group and the fructose group (P>0.05). After treatment, the L-carnitine group and the fructose group had significant reductions in the indices of myocardial zymogram and levels of MDA, sFas, and sFasL and a significant increase in the level of SOD (P<0.05); the fructose group had a significantly higher level of creatine kinase (CK) than the control group and the L-carnitine group, and there were no significant differences in other myocardial enzyme indices, MDA, sFas, and sFasL between the L-carnitine group and the fructose group, as well as between the L-carnitine and fructose groups and the control group (P>0.05). SOD level was negatively correlated with aspartate aminotransferase, lactate dehydrogenase (LDH), CK, and creatine kinase-MB (CK-MB) (r=-0.437, -0.364, -0.397, and -0.519 respectively; P<0.05), and MDA level was positively correlated with LDH and CK-MB (r=0.382 and 0.411 respectively; P<0.05).

CONCLUSIONSL-carnitine exerts a good myocardial protective effect in children with HFMD caused by Coxsackie A16 virus, possibly by clearing oxygen radicals and inhibiting cardiomyocyte apoptosis.

Carnitine ; therapeutic use ; Child, Preschool ; Coxsackievirus Infections ; complications ; Female ; Hand, Foot and Mouth Disease ; drug therapy ; etiology ; metabolism ; Heart ; drug effects ; Humans ; Infant ; Male ; Malondialdehyde ; analysis ; Myocardium ; metabolism ; pathology ; Superoxide Dismutase ; metabolism

OBJECTIVETo investigate the effect of tranilast on myocardial fibrosis in mice with viral myocarditis (VMC).

METHODSMale balb/c mice (n=72) were randomly divided into control, VMC and tranilast groups (n=24 each). In the VMC and tranilast groups, the mice were infected with Coxsackie virus B3 (CVB3) to prepare VMC model, while the control group was treated with Eagle's medium. After modeling, the tranilast group was administrated with tranilast [200 mg/(kg.d)] until the day before sampling. On days 7, 14 and 28 after CVB3 or Eagle's medium infection, heart specimens (n=8) were taken and examined after Toluidine blue staining and Nissl staining for counts of mast cells (MC), hematoxylin-eosin staining for myocardial pathological changes, and Masson staining for myocardial fibrosis. The expression of CTGF and type I collagen (Col I) in the myocardial tissue was measured by RT-PCR and Western blot. The correlations of CTGF mRNA expression with MC counts and Col I expression were analyzed.

RESULTSThe myocardial pathological changes and collagen volume fraction in the VMC group were significantly higher than in the control group at all three time points (P<0.05). Tranilast treatment significantly decreased the myocardial pathological changes and collagen volume fraction compared with the VMC group (P<0.05). The mRNA and protein expression of CTGF and Col I increased in the VMC group compared with the control group, and the increases were reduced with tranilast treatment (P<0.05). The number of MC was positively correlated to CTGF mRNA expression on the 7th day and 14th day (r=0.439, P=0.049) in the VMC group. There were positive correlations between the mRNA expression of Col I and CTGF on the 7th day and 14th day (r=0.646, P=0.007) and the 28th day (r=0.326, P=0.031).

CONCLUSIONSTranilast may inhibit the aggregation of MC and down-regulate the expression of CTGF, relieving myocardial fibrosis of mice with VMC.

Animals ; Collagen Type I ; genetics ; Connective Tissue Growth Factor ; genetics ; Coxsackievirus Infections ; drug therapy ; Enterovirus B, Human ; Fibrosis ; Male ; Mice ; Mice, Inbred BALB C ; Myocarditis ; drug therapy ; Myocardium ; pathology ; RNA, Messenger ; analysis ; ortho-Aminobenzoates ; pharmacology

OBJECTIVETo investigate the dynamic expression and role of vitamin D receptor (VDR) in the myocardium of mice with viral myocarditis (VMC).

METHODSOne hundred and twenty 4-week-old male BALB/c mice were selected and assigned into control (n=40) and experimental groups (n=80). The mice in the experimental group were injected intraperitoneally with Coxsackievirus B3 to establish the model of VMC, while the mice in the control group were injected intraperitoneally with an equal volume of DMEM solution. Fifteen mice in the experimental group and ten mice in the control group were sacrificed at 3, 7, 14, or 28 days after injection, and the myocardial specimens were obtained. The dynamic expression of VDR in the myocardium was determined by the immunohistochemical technique. The pathological changes in the myocardium were examined using hematoxylin and eosin staining.

RESULTSIn the experimental group, the mice had significantly increased expression of VDR after virus injection (P<0.01); the expression of VDR reached the peak at 7 days after injection, and then declined gradually; the expression of VDR remained high at 28 days after injection. At 3, 7, 14, and 28 days after injection, the expression of VDR in the experimental group was significantly higher than that in the control group (P<0.01). Moreover, in the experimental group, the changes in the pathological score of the myocardium were in accordance with the changes in the expression of VDR; the expression level of VDR in the myocardium was positively correlated with the pathological changes in the myocardium in the experimental group (P<0.01).

CONCLUSIONSVDR may be involved in the inflammatory-immune process in the pathogenesis of VMC.

Animals ; Coxsackievirus Infections ; metabolism ; Enterovirus B, Human ; Immunohistochemistry ; Male ; Mice ; Mice, Inbred BALB C ; Myocarditis ; metabolism ; pathology ; Myocardium ; chemistry ; pathology ; Receptors, Calcitriol ; analysis ; physiology

OBJECTIVE: Astragaloside is a simple substance of saponin and the active constituent of astragali. It was reported that the astragaloside exerted therapeutical eff ect on viral myocarditis and dilated cardiomyopathy. The purpose of this study was to investigate the effect of astragaloside on TL1A expression in viral myocarditis. METHODS: A total of 100 BALB/c mice were randomly divided into 6 groups: the normal control group (group A, n=10), the high-dose control group (group B, n=10), the myocarditis control group (group C, n=20), the low-dose group (group D, n=20), the middle-dose group (group E, n=20) and the high-dose group (group F, n=20). Mice in group A and group B were injected intraperitoneally with 0.1 mL EMEM solution, while mice in group C, D, E and F were treated with 0.1 mL of 1×102 TCID50 CVB3 (diluted in EMEM). Then, mice in group A and group B were treated with carboxymethycellulose solution and 9% astragaloside for 1 week, respectively. At the same time, mice in group C, D, E and F were treated with sodium carboxymethycellulose solution, 1% [0.07 g/(kg.d)], 3% [0.2 g/(kg.d)] and 9%[0.6 g/(kg.d)] astragaloside for 1 week, respectively. After 14 days, the mice were sacrificed and their hearts were collected. The expression levels of TL1A mRNA and protein in the myocardium were examined by RT-PCR and immunohistochemistry, respectively. RESULTS: There was no death in the group A and B. The mortality in the group C, D, E and F was 45% (9/20), 30% (6/20), 25% (5/20) and 10% (2/20), respectively. Compared with the group C, the mortality in the group F was significantly decreased (P<0.05), but there no significant difference in mortality between the group C and the group D or E (P>0.05). There was no any pathological lesion in the group A and B. The TL1A mRNA and protein expression in the myocardium of mice in the group A and B was at low level, with no difference between them (P>0.05). Compared with the group A, the expression levels of TL1A mRNA and protein in the group C were markedly up-regulated (P<0.01), which was dramatically attenuated by the intervention of astragaloside at high dosage (the group F, P<0.01) but not at low (the group D) or middle-dosage (the group E) (P>0.05). CONCLUSION Astragaloside may play a pivotal role in protection of the heart injury in viral myocarditis by suppressing the expression of TL1A.
Acute Disease ; Animals ; Cardiomyopathy, Dilated ; drug therapy ; Coxsackievirus Infections ; drug therapy ; Drugs, Chinese Herbal ; pharmacology ; Mice ; Mice, Inbred BALB C ; Myocarditis ; drug therapy ; virology ; Myocardium ; metabolism ; pathology ; RNA, Messenger ; Saponins ; pharmacology ; Tumor Necrosis Factor Ligand Superfamily Member 15 ; metabolism ; Up-Regulation

OBJECTIVETo explore the apoptotic pathway mediated by endoplasmic reticulum stress in the mouse myocardium with heart failure induced by acute viral myocarditis caused by B-3 Coxsackie virus.

METHODSForty BALB/c male mice were randomly divided into 2 groups (n = 20): the control group and the virus infection group. The BALB/c mouse myocarditis was induced by B-3 Coxsackie virus and the mouse behavior was observed conventionally. All the mice were sacrificed on day 7 and the changes of left ventricular pressure (LVP) and the rate of change of left ventricular pressure (LV dp/dt) were measured. The cardiomyocytic apoptosis was analyzed by TUNEL method and the mRNA expression level of endoplasmic reticulum haperones glucose-regulated protein (GRP)78 and GRP94 was detected by RT-PCR.

RESULTS(1) Compared with those of control group, the parameters of cardiac hemodynamics in the virus infection group were significantly decreased (P < 0.01); (2) Compared with that of control group, myocardial apoptosis was significantly increased in the myocardial cells from mice with heart failure induced by acute viral myocarditis (P < 0.01); (3) The mRNA expression level of GRP78 and GRP94 were increased significantly in the virus infection group compared with the control group.

CONCLUSIONThese findings suggest the endoplasmic reticulum stress may mediate the apoptosis of myocardial cells in the mice myocardium of heart failure induced by acute viral myocarditis caused by B-3 Coxsackie virus.

Animals ; Apoptosis ; Coxsackievirus Infections ; physiopathology ; Endoplasmic Reticulum Stress ; Heart ; physiopathology ; Heart Failure ; physiopathology ; virology ; Heat-Shock Proteins ; metabolism ; Male ; Membrane Glycoproteins ; metabolism ; Mice ; Mice, Inbred BALB C ; Myocarditis ; physiopathology ; virology ; Myocardium ; pathology ; Myocytes, Cardiac ; cytology

OBJECTIVETo investigate the role and significance of cardiac mast cells and Toll-like receptor 4 (TLR4) in the development and progression of viral myocarditis (VMC).

METHODSForty-eight Balb/c mice were randomly divided into a control group (n=24) and a model group (n=24). Coxsackievirus B3 was intraperitoneally injected into the model group mice to establish a VMC model. In each group, cardiac tissues were collected from 8 mice at 7, 14 and 28 days after the model was established. The cardiac tissues were stained with hematoxylin and eosin as well as Masson trichrome to observe pathological changes in cardiac tissues. The number and degranulation of cardiac mast cells at each time point were measured and evaluated by toluidine blue staining and transmission electron microscopy. The mRNA and protein expression of TLR4 in cardiac tissues was measured by RT-PCR and immunohistochemistry. In the model group, the correlation between number of cardiac mast cells and mRNA expression of TLR4 at all time points was analyzed.

RESULTSThe model group had significantly higher pathological scores of cardiac tissues than the control group at all time points (P<0.05). The myocardial collagen volume fraction in the model group at 28 days was significantly higher than in the control group at all time points and higher than in the model group at 7 and 14 days (P<0.05). At each time point, the model group had a significantly increased number of mast cells (P<0.05), and significantly increased mRNA and protein expression of TLR4 (P<0.05) compared with the control group. In the model group, the number of cardiac mast cells was positively correlated with the mRNA expression of TLR4 at all time points (R²=0.877, P<0.05).

CONCLUSIONSMice with VMC have significantly increased numbers of cardiac mast cells and expression of TLR4 compared with control mice at all time points, suggesting that mast cells and TLR4 may play important roles in the inflammatory response and fibrosis of VMC.

Animals ; Coxsackievirus Infections ; immunology ; Enterovirus B, Human ; Female ; Mast Cells ; physiology ; Mice ; Mice, Inbred BALB C ; Myocarditis ; immunology ; Myocytes, Cardiac ; pathology ; Toll-Like Receptor 4 ; analysis ; genetics ; physiology

Coxsackievirus A16 belongs to the family Picornaviridae, and is a major agent of hand-foot-and-mouth disease that infects mostly children, and to date no vaccines or antiviral therapies are available. 2A protease of enterovirus is a nonstructural protein and possesses both self-cleavage activity and the ability to cleave the eukaryotic translation initiation factor 4G. Here we present the crystal structure of coxsackievirus A16 2A protease, which interestingly forms hexamers in crystal as well as in solution. This structure shows an open conformation, with its active site accessible, ready for substrate binding and cleavage activity. In conjunction with a previously reported "closed" state structure of human rhinovirus 2, we were able to develop a detailed hypothesis for the conformational conversion triggered by two "switcher" residues Glu88 and Tyr89 located within the bll2-cII loop. Substrate recognition assays revealed that amino acid residues P1', P2 and P4 are essential for substrate specificity, which was verified by our substrate binding model. In addition, we compared the in vitro cleavage efficiency of 2A proteases from coxsackievirus A16 and enterovirus 71 upon the same substrates by fluorescence resonance energy transfer (FRET), and observed higher protease activity of enterovirus 71 compared to that of coxsackievirus A16. In conclusion, our study shows an open conformation of coxsackievirus A16 2A protease and the underlying mechanisms for conformational conversion and substrate specificity. These new insights should facilitate the future rational design of efficient 2A protease inhibitors.
Coxsackievirus Infections ; virology ; Crystallography, X-Ray ; Cysteine Endopeptidases ; chemistry ; genetics ; Fluorescence Resonance Energy Transfer ; Hand, Foot and Mouth Disease ; enzymology ; pathology ; virology ; Humans ; Picornaviridae ; chemistry ; enzymology ; genetics ; Protein Conformation ; Structure-Activity Relationship ; Substrate Specificity ; Viral Proteins ; chemistry ; genetics

OBJECTIVE: To discuss the myocardial expression of Spry1 and MAPK proteins of viral myocarditis (VMC), to reveal its mechanism of sudden death, and to provide guides for forensic identification of sudden cardiac death. METHODS: Thirty Balb/c male mice were randomly divided into VMC group and control group, inoculated intraperitoneally with Coxsackievirus B3 and Eagel's solution, respectively. After the mice were sacrificed, the cardiac tissues of the mice were taken to proceed regular pathological examination. The changes of Spry1 protein, Spry1 mRNA and MAPK protein were detected by immunohistochemistry, Western blotting and real-time PCR. RESULTS: Under light microscope, the pathologic changes included myocardial interstitial edema, inflammatory cells infiltration, myocardial necrosis, and focal and patchy necrosis of myocardial fiber in VMC group. The expression of Spry1 protein in VMC group was lower than that in control group (P < 0.05). There was slightly decreased expression of Spry1 of the mRNA level in VMC group (P > 0.05). But the MAPK protein expression in VMC group was higher than that in control group (P < 0.05). CONCLUSION The pathway of MAPK/ERK involving Spry1 protein accelerates the expression of collagen, which may contribute to arrhythmia, heart failure and even sudden cardiac death.
Adaptor Proteins, Signal Transducing/metabolism* ; Animals ; Coxsackievirus Infections/pathology* ; Death, Sudden, Cardiac/pathology* ; Disease Models, Animal ; Immunohistochemistry ; Male ; Membrane Proteins/metabolism* ; Mice ; Mice, Inbred BALB C ; Mitogen-Activated Protein Kinases/metabolism* ; Myocarditis/virology* ; Myocardium/pathology* ; Phosphoproteins/metabolism* ; RNA, Messenger/metabolism* ; Random Allocation ; Real-Time Polymerase Chain Reaction

OBJECTIVETo investigate the relationship between endothelial-to-mesenchymal transition (EndMT) and myocardial fibrosis in acute viral myocarditis (VMC).

METHODSTwenty-eight Balb/c mice were randomized into 3 groups: control group (n=8), VMC group(n=10) and intervention group(n=10). Mice in VMC and intervention groups were injected intraperitoneally(i.p) with single dose of coxsackievirus B3, mice in control group were injected with equal amount of viral-free vehicle. In the following day, mice in control and VMC groups were injected i.p with 0.1 ml of saline and intervention group with 0.1 ml of recombinant human bone morphogenetic protein 7(rh-BMP7) at a concentration of 300 μg/kg. The mice hearts were harvested after 7 d, cardiac collagen volume fraction (CVF) was calculated on picrosirius red-stained sections. mRNA and protein expression of TGF-β1, CD31, VE-cadherin, fibroblast special protein 1 (FSP-1) and α-smooth muscle actin (α-SMA) and collagen 1α1 in myocardiac tissues were detected by real-time RT-PCR and Western blot analysis, respectively.

RESULTSCompared to controls, overt fibrosis was presented in necrotic area of myocardium in VMC group. Meanwhile, marked increase of TGF-β1 expression accompanied with EndMT characterized by loss of endothelial phenotype (decreased expression of CD31 and VE-cadherin), gain of mesenchymal proteins (overexpression of FSP-1 and α-SMA) and increased synthesis of collagen was also demonstrated. Both EndMT and cardiac fibrosis were simultaneously reversed by TGF-β1 inhibition.

CONCLUSIONEndMT is involved in cardiac fibrosis in acute viral myocarditis, TGF-β1 might be a main mediator.

Acute Disease ; Animals ; Antigens, CD ; metabolism ; Cadherins ; metabolism ; Collagen ; metabolism ; Coxsackievirus Infections ; metabolism ; pathology ; Disease Models, Animal ; Endothelium ; pathology ; Fibrosis ; Male ; Mesoderm ; pathology ; Mice ; Mice, Inbred BALB C ; Myocarditis ; metabolism ; pathology ; virology ; Myocardium ; metabolism ; pathology ; Transforming Growth Factor beta1 ; metabolism

BACKGROUNDMacrophage migration inhibitory factor (MIF) is an upstream regulator in immune and inflammatory responses. However, its role in viral myocarditis remains unknown. In this study, we investigated the role of the MIF in coxsackievirus B3 (CVB3)-induced myocarditis.

METHODSMice were randomized into two groups receiving either Eagle's minimal essential medium (EMEM, control group) or virus solution (infected group). Subsets of mice in the infected group were sacrificed on days 3, 7, 14 and 28 after inoculation. Expression of MIF was detected using an enzyme-linked immunosorbent assay (ELISA), reverse transcription polymerase chain reaction and immunohistochemistry. A neutralizing antibody (Ab) to MIF was injected intraperitoneally from day 0 to 7 after inoculation. Disease severity was estimated by histopathology of the heart and by the heart weight to body weight ratio, and the interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α) in the myocardium were measured by ELISA on day 14.

RESULTSThe serum MIF concentration and expression levels of myocardial MIF mRNA and protein were significantly elevated in mice on days 7 and 14 post-infection. The survival rate was markedly higher and disease severity was obviously less in mice treated with anti-MIF Ab. Furthermore, MIF blockade significantly decreased the IL-1β and TNF-α in the myocarditic heart.

CONCLUSIONThese results demonstrate that MIF is an important naturally occurring inflammatory cytokine in CVB3-induced myocarditis, and anti-MIF Ab may lessen the inflammatory response.

Animals ; Coxsackievirus Infections ; metabolism ; pathology ; virology ; Enterovirus B, Human ; Enzyme-Linked Immunosorbent Assay ; Immunohistochemistry ; Interleukin-1beta ; metabolism ; Macrophage Migration-Inhibitory Factors ; metabolism ; Male ; Mice ; Mice, Inbred BALB C ; Myocarditis ; metabolism ; pathology ; virology ; Myocardium ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Tumor Necrosis Factor-alpha ; metabolism