Clinical significance and pathogenic role of anti-cardiac myosin autoantibody in dilated cardiomyopathy

Objective In order to explore the possible roles played by the autoimmune mechanism in the progression of myocarditis into dilated cardiomyopathy (DCM) using an animal model, we investigated whether autoimmune myocarditis might develop into DCM.Methods Experimental Balb/C mice (n = 20) were immunized with cardiac myosin with Freund‘s complete adjuvant at days 0, 7 and 30. The control Balb/C mice ( n = 10 ) were immunized with Freund‘s complete adjuvant in the same mannere. Serum and myocardium samples were collected after the first immunization at clays 15, 21 and 120. The anti-myosin antibody was examined by enzyme-linked immunosorbent assay and immunoblotting.Results Pathological findings demonstrated that there was myocardial necrosis or inflammatory infiltration during acute stages and fibrosis mainly in the late phase of experimental group, but the myocardial lesions were not found in the control group. Autoimmunity could induce myocarditis andDCM in the absence of viral infection. High titer anti-myosin IgG antibodies were found in theexperimental group, but not in the control group. Furthermore, the anti-myosin heavy chain (200 KD)antibody was positive in 21 of 48 patients with DCM and viral myocarditis, but only 4 of 20 patients with coronary heart disease, including 1 case and 3 cases that reacted with heavy and light chains(27. 5 KD), respectively. The antibodies were not detected in healthy donors.Conclusion Cardiac myosin might be an autoantigen that provokes autoimmunity and leads to the transformation of myocarditis into DCM. Detection of anti-myosin heavy chain antibody might contribute to diagnosis for DCM and viral myocarditis.     

High-frequency ultrasound evaluation of effects of early treatment with metoprolol on myocardial inflammatory cytokine expression in rats with acute myocardial infarction

This study evaluated the effects of early treatment with β-adrenergic blocker metoprolol on ventricular remodeling and function after acute myocardial infarction (AMI) by using high frequency ultrasound.The relationship between the efficacy and the expression level of cardiac myocardial inflammatory cytokine was examined in rats.The rat model of AMI was induced by ligating the left ante-rior descending artery.The surviving rats were randomly assigned to two experimental groups:MI control (MI) group and MI metoprolol (MI-B) group,with the rats undergoing sham operation serving as normal control (Sham).MI-B group was given metoprolol for 4 weeks (refer to the CCS-2 protocol) and the other two groups received equal volume of saline via intragastric (i.g.) administation.The ventricular remodeling and function were evaluated by high frequency ultrasound 4 weeks after the treatment.Then all rats were sacrificed for pathological examination and immunohistochemistrical detection of inflammatory cytokines,including IL-1β,IL-6,IL-10 and TNF-α.Compared with the MI group,the left ventricular end-systolic dimension,end-diastolic dimension,end-systolic volume and end-diastolic volume of the MI-B group were significantly decreased (P<0.01),while the left ventricular anterior wall end-diastolic thickness,ejection fraction and fractional shortening were obviously increased (P<0.01).The conspicuous improvement in the left ventricular morphology and function was coincident with the markedly reduced TNF-α and IL-1β expression and the increased IL-10 expression.We are led to conclude that early metoprolol treatment for AMI can regulate myocardial inflammatory cytokine expression to improve cardiac function and the underlying mechanism might be that it decreases the level of pro-inflammatory cytokines and increases the level of its anti-inflammatory counterparts in cardiac myocytes.Our study also showed that echocardiography is a useful technique for the structural and functional assessment of left ventricle after acute my     

The effect of spinal cord injury on the expression of TGF-β and TNF-α in rat articular cartilage

Objective： To observe the expression of TGF-β and TNF-α in the spinal cord injured rat model and discuss the significance of the articular cartilage metabolism. Methods： 36 SD female rats were randomly divided into 2 groups： Rats models of spinal cord injury were implemented by Allen method. T10 laminectomy was performed in the control group. Both groups of rats were killed respectively in 1w, 3w and 6w. Hematoxylin-eosin stain was given to each slice in the model group and control group. Immunohistochemical stain was applied by using ABC method in the expression of TGF-β and TNF-α. Those expressed level were performed in image analysis and statistics process. Results： TGF-β and TNF-α were mainly distributed on the surface layer of the articular cartilage, with a weak expression in control group. The expression of TNF-α in the model group was more significant than that in the control group in the lw, and still remained an evident difference with that in control group until the 6w（P 〈 0.05）. TGF-β expression of the model group had no remarkable difference with the control group in the lw （P 〉 0.05） and prominently became stronger at 6w（P 〈 0.05）. Conclusion： The expression of TNF-α occurred early in the development of spinal cord injury, and the expression of TGF-β became stronger with the revival of spinal neural function. Both expressions were strengthened in articular cartilage in the 3rd week.     

Matrix metalloproteinase-8 inhibitors mitigate sepsis-induced myocardial injury in rats

Background Sepsis-induced myocardial injury （SIMI） is caused by a variety of mechanisms. The aim of the study is to investigate the effects of metalloproteinase-8 （MMP-8） on SIMI and its mechanisms in rats. Methods Forty male Sprague Dawley rats were randomly divided into four groups： MMP-8 inhibitor （M81）, dexamethasone （DEX）, sepsis, and sham groups. The sepsis model was established by cecal ligation and puncture （CLP）. Rats in the M81 group immediately received an intraperitoneal injection of M81 （0.1 mg/kg） after CLP. Rats in the DEX group immediately received an intraperitoneal （IP） injection of DEX （2 mg/kg）. Rats in the sepsis and sham groups received intraperitoneal injections of normal saline. Rats were sacrificed 12 hours after CLP. Paraffin sections were stained with hematoxylin and eosin to observe the myocardium. The myocardial ultrastructure was observed with transmission electron microscopy. MMP-8, tumor necrosis factor-Q （TNF-a）, and interleukin-113 （IL-113） were detected by immunohistochemistry. The expression of MMP-8 was measured by Western blotting. TNF-a and IL-113 levels in serum and myocardial tissue were determined by enzyme-linked immunosorbent assay. Results Compared with the sham group, the myocardium in the sepsis group was seriously injured. MMP-8, TNF-α and IL-1β expression was higher in the sepsis group than in the sham group, Treatment with M81 or DEX, however, attenuated sepsis induced histopathological changes in the heart, and was associated with significant reductions in serum and myocardial levels of TNF-a and IL-113 （P 〈0.05）. M81 significantly inhibited MMP-8 expression in myocardial tissue （P 〈0.05）. In addition, treatment with DEX was not associated with a change in myocardial levels of MMP-8 （P 〉0.05）. Conclusion MMP-8 inhibitor attenuated myocardial injury in septic rats, which might be related to reduced expression of TNF-α and IL-1β.     

Electrophysiological and pathological observations on experimental coxsackie B-3 viral myocarditis in mice.

Electrophysiological action of right ventricular myocardium examined by standard intracellular microelectrode technique and real-time microcomputer data processor system and histological and ultrastructural changes of myocardium in BALB/c mice infected with coxsackie B-3 virus from 3 days to 9 months were observed. It was found that electrophysiologic parameters of action potential changed very quickly at the early stage (3 days to 1 month) of the disease. Those abnormalities became most apparent by the 5-30th day, and 7 patterns of abnormal action potential occurred frequently within the same period. These changes were basically parallel to the myocardial lesions. At the late stage (3-9 months) the electrophysiological parameters were nearly normal, while the myocardial lesions decreased gradually. However, the abnormal patterns of action potential were still detected, even though they were improved gradually. The results suggest that myocardial damages caused by viral infection may lead to changes of cardiac electric action, which may be one of the factors in arrhythmias in the episode of viral myocarditis.

     

Assessment of the number and function of macrophages in the placenta of gestational diabetes mellitus patients

In order to assess the number and function of macrophages in the placenta of pregnancy complicated with gestational diabetes mellitus （GDM） as well as those of normal pregnancies, placenta samples were collected from 15 GDM patients （GDM group） and 10 normal pregnant women （control group）. The expression levels of macrophage markers （CD68/CD14） and inflammatory cytokines （IL-6/TNF-α） in placenta were detected using immunohistochemistry and PCR. The results showed that the number of CD68＋ or CD14＋ cells in the GMD group was remarkably higher than that in the control group （P〈0.05）, indicating that the number of macrophages in the GDM group was significantly greater than that in the control group. The mRNA expression levels of CD68＋, IL-6 and TNF-α were higher in the GMD group than in the control group. In conclusion, more macrophages accumulate in placenta of pregnancy complicated with GDM, and the expression levels of pro-inflammation factors are also in- creased in GDM pregnancies, suggesting that macrophages and inflammatory mediators （IL-6 and TNF-α） mav olav an imoortant role in GDM.     

Microarray analysis of extracellular matrix genes expression in myocardium of mouse with Coxsackie virus B3 myocarditis

Background Extracellular matrix (ECM) orchestrates cell behaviour including growth, death, apoptosis, adhesion, migration, and invasion by activating several signalling pathways. Certain components of ECM, such as integrins, may act as receptors or co-receptors of enterovirus. ECMactivated gene expressions in myocardium of viral heart disease including myocarditis and partial cardiomyopathy remain elusive. This study was to investigate the expression of ECM-activated genes in myocardium of mouse with viral myocarditis. Methods BALB/c mice were infected with Coxsackie virus B3 (CVB3) to establish an animal model of myocarditis. Uninfected mice were also prepared and served as controls. Specific mRNA expression pattern in myocarditic mouse heart was analysed by an in-house cDNA microarray containing 8192 genes. Overexpressed ECM genes were selected and subsequently confirmed by Northern blot analysis. Results Nine ECM genes were isolated, from the array of 8192 genes, as overexpressed genes in hearts of myocarditic mice in comparison with controls. Subsequent Northern blot analysis confirmed that four of the nine genes were highly expressed. Expression of these four genes, Fin15, ILk, Lamrl and ADAMTS-1, has not been reported previously to be induced by Coxsackie virus. Conclusion CVB3-induced myocarditis is associated with gene expression profiles of certain ECM components.     

Ketamine Promotes Inflammation through Increasing TLR4 Expression in RAW264.7 Cells

Summery: Ketamine(KTM), a N-methyl-D-aspartate(NMDA) receptor antagonist, was found to has an anti-inflammatory effect, but some patients suffered from exacerbated pro-inflammatory reactions after anesthesia with KTM. The present study was aimed to examine the underlying mechanism of pro-inflammatory effects of KTM. In this study, RAW264.7 cells were exposed to KTM and NMDA alone or combined for 30 min before lipopolysaccharide(LPS) stimulation. The expression levels of IL-6 and TNF-α were detected by RT-PCR and ELISA, and those of NMDA receptors by RT-PCR in RAW264.7 cells. Additionally, the TLR4 expression was determined by RT-PCR and flow cytometry, respectively. The results showed that in RAW264.7 cells, KTM alone promoted the TLR4 expression, but did not increase the expression of IL-6 or TNF-α. In the presence of LPS, KTM caused a significantly higher expression of IL-6 and TNF-α than LPS alone. NMDA could neither alter the IL-6 and TNF-α m RNA expression, nor reverse the enhanced expression of IL-6 and TNF-α m RNA by KTM in LPS-challenged cells. After TLR4-si RNA transfection, RAW264.7 cells pretreated with KTM no longer promoted the IL-6 and TNF-α expression in the presence of LPS. In conclusion, KTM accelerated LPS-induced inflammation in RAW264.7 cells by promoting TLR4 expression, independent of NMDA receptor.     

The Expression of TNF-α and ICAM-1 in Lesions of Lichen Planus and Its Implication

In order to investigate the role of TNF-α and ICAM-1 in the pathogenesis of lichen planus, immunohistochemistry was used to detect the expression of TNF-α and ICAM-1 in skin le- sions of the patients with lichen planus and skin tissues of normal subjects. The results showed that positive rates of TNF-α and ICAM-1 expressions in lichen planus were significantly higher than those in normal skins (both P<0.05). Meanwhile, there was a obvious correlation between the in- crease of TNF-α and that of ICAM-1 in lichen planus. The expression of TNF-α and ICAM-1 might play an important role in the development of lichen planus.     

The Effect of Ginkgo Biloba Extract on the Expression of PKCα in the Inflammatory Cells and the Level of IL-5 in Induced Sputum of Asthmatic Patients

To investigate the effect of the Ginkgo Biloba Extract （GBE） on the asthma and examine its possible mechanisms, 75 asthma patients were divided into 4 groups and the patients were respectively treated with fluticasone propionate for 2 weeks or 4 weeks, or treated with fluticasone propionate plus GBE for 2 weeks or 4 weeks. Fifteen healthy volunteers served as healthy controls. Sputum inhalation with inhaling hypertonic saline （4%-5%） was performed. Lung ventilatory function and forced expiratory volume in one second （FEVI） were measured. The numbers of different cells in induced sputum were calculated. The expression of PKCα in the cells was immunocytochemically detected and the percentages of positive cells in different cells were counted. Interleukin-5 （IL-5） in sputum supernatants was detected with enzyme-linked immunosorbent assay. The percentage of eosinophils, lymphocytes, PKCα positive inflammatory cells and the concentration of IL-5 in asthmatic patients were higher than those in the controls （P〈0.05）, and the eosinophils, lymphocytes, positive expression of PKCα and the level of IL-5 were significantly decreased in asthmatic patients after they were treated with fluticasone propionate or fluticasone propionate plus GBE. However, they were still significantly higher than those of the controls. Compared to the group treated with glucocorticosteroid for 2 weeks, no significant decrease was found in the percentage of eosinophils, lymphocytes, PKCα positive inflammatory cells and the IL-5 in the supernatant of induced sputum. Compared with the group treated with glucocorticosteroid for 2 or 4 weeks, significant decrease in the same parameters was observed in the group treated with fluticasone propionate and GBE for 4 weeks. The IL-5 level in the supernatant of induced sputum was positively correlated with the percentage of PKCα-positive inflammatory cells and the percentage of eosinophils in the induced sputum in asthma patient groups respectively （n=150, r=0.83, P〈0.01; n=150,     

Expression of Toll-like receptor 4 in neonatal cord blood mononuclear cells in patients with preeclampsia

The expression of Toll-like receptor 4 (TLR4) in neonatal cord blood mononuclear cells (MNCs) and serum TNF-α were investigated in order to explore the roles of TLR4 in the pathogenesis of preeclampsia.The study enrolled 27 patients suffering from preeclampsia (experimental group) and 21 normal pregnancy patients (control group).After MNCs were separated, the expression of TLR4 mRNA and protein was detected by using real-time quantitative PCR and Western blotting respectively, and the expression of TNF-α by using ELISA.The results showed the TLR4 mRNA level in cord blood MNCs (2-CT:0.07±0.17), TLR4 protein expression level (absorbance ratio:0.81%±0.15%) and TNF-α level (9.5±1.73 pg/mL) were all increased in experimental group as compared with control group with the differences being statistically significant (P<0.05).There was a positive correlation between the expression of TLR4 mRNA and TNF-α in both experimental group and control group (r=0.54 and 0.53, respectively, P<0.05).It was concluded that TLR4 expression in the experimental group of cord blood MNCs was increased and there was a positive correlation between the expression of TLR4 mRNA and TNF-α in both groups.TLR4-mediated release of inflammatory cytokines may be one of the important reasons leading to preeclampsia.     

EFFECT OF PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR ACTIVATORS ON TUMOR NECROSIS FACTOR-αL EXPRESSION IN NEONATAL RAT CARDIAC MYOCYTES A

Objecfive To investigate the effect ofperoxisome proliferator-αctivated receptor-α (PPARα) and PPARγ activators on tumor necrosis factor-α (TNFα) expression in neonatal rat cardiac myocytes. Primary cultures of cardiac myocytes from 1- to 3-dayold Wistar rats were prepared, and myocytes were ex-posed to lipopolysaccharide (LPS) and varying concentrations of PPARα or PPARγ activator (fenofibrate or pioglitazone).RT-PCR and ELISA were used to measure TNFα, PPARα, and PPARγ expression in cultured cardiac myocytes. Transient transfection of TNFα promoter with or without nuclear factor-kappaB (NF-κB) binding site to cardiac myocytes was performed. Performed Pretreatment of cardiac myocytes with fenofibrate or pioglitazone inhibited LPS-induced TNFα mRNA and protein expression in a dose-dependent manner. However, no significant changes were observed on PPARα or PPARα mRNA expression when cardiac myocytes were pretreated with fenofibrate or pioglitazone. Proportional suppression of TNFα promoter activity was observed when myocytes was transiently transfected with whole length of TNFα promoter (-721/ 17) after being stimulated with LPS and fenofibrate or pioglitazone, whereas no change of promoter activity was observed with transfection of TNFα reporter construct in deletion of NF-κBbinding site (- 182/ 17). Conchusions PPARα and PPARγ activators may inhibit cardiac TNFα expression but not accompanied by change of PPARα or PPARγ mRNA expression. Therefore PPARα and PPARγ activators appear to play a role in anti-inflammation.The mechanism may partly be involved in suppression of the NF-κBpathway.     

Lentivector-mediated RNAi efficiently downregulates expression of murine TNF-α gene in vitro and in vivo

In order to explore the role of TNF-α in Niemann-Pick type C （NPC） disease, lentiviral-delivered RNA interference （RNAi） was used to silence the expression of murine TNF-α gene in vitro and in npc mice. Interference efficiency of the lentivirus expressing TNF-α-siRNA, previously constructed with the concentration of 2 x 108 ifu/mL, was determined by RT-PCR and ELISA in BV-2 cells and astrocytes. At the same time, the constructed Lenti-TNF-α-siRNA was intracerebroventricularly infused into 4-week old npc mice for a 4-week period, and the mice were divided into 3 groups： Lenti-TNF-α-siRNA （n=6）, control lentivirus （n=6）, and NPC mice without any intervention （n=4）. By using immunohistochemistry and real-time PCR, the down-regulation of the target genes was detected. The Lenti-TNF-α-siRNA downregulated the expression of murine TNF-α gene efficiently in vitro and the interference efficiency was 66.7%. Lentivirus could be expressed stably for long-term in the npc mice brain. Immunohistochemistry and real-time PCR revealed that, as compared with non-intervention group and Lenti-control group, Lenti-TNF-α-siRNA efficiently down-regulated the expression of murine TNF-α gene with the interference efficiency being 66.9%. TNF-α-siRNA downregulated the expression of TNF-α gene in vitro and in vivo, which provided a potential tool for studying and treating neurodegenerative diseases and TNF-α-related diseases.     

EFFECT OF PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR ACTIVATORS ON TUMOR NECROSIS FACTOR-α EXPRESSION IN NEONATAL RAT CARDIAC MYOCYTES

Objective To investigate the effect ofperoxisome proliferator-activated receptor-α (PPARα) and PPARγ activators on tumor necrosis factor-α (TNFα) expression in neonatal rat cardiac myocytes.Methods Primary cultures of cardiac myocytes from 1- to 3-day-old Wistar rats were prepared, and myocytes were exposed to lipopolysaccharide (LPS) and varying concentrations of PPARα or PPARγ activator (fenofibrate or pioglitazone).RT-PCR and ELISA were used to measure TNFα, PPARα, and PPARγexpression in cultured cardiac myocytes. Transient transfection of TNFα promoter with or without nuclear factor-kappaB (NF-κB) binding site to cardiac myocytes was performed.Results Pretreatment of cardiac myocytes with fenofibrate or pioglitazone inhibited LPS-induced TNFα mRNA and protein expression in a dose-dependent manner. However, no significant changes were observed on PPARα or PPARγ mRNA expression when cardiac myocytes were pretreated with fenofibrate or pioglitazone. Proportional suppression of TNFαpromoter activity was observed when myocytes was transiently transfected with whole length of TNFα promoter (-721/ 17) after being stimulated with LPS and fenofibrate or pioglitazone, whereas no change of promoter activity was observed with transfection of TNFα reporter construct in deletion of NF-κB binding site (-182/ 17).Conclusions PPARα and PPARγ activators may inhibit cardiac TNFα expression but not accompanied by change of PPARα or PPARγmRNA expression. Therefore PPARα and PPARγ activators appear to play a role in anti-inflammation.The mechanism may partly be involved in suppression of the NF-κB pathway.     

Aspirin inhibits tumor necrosis factor-α-stimulated fractalkine expression in human umbilical vein endothelial cells

Background Fractalkine is an important chemokine mediating local monocyte accumulation and inflammatory reactions in the vascular wall. Aspirin inhibits inflammatory cytokine expression closely related to atherosclerosis through the way independent of platelet and cyclooxygenase （COX）. There has been no report about the effect of aspirin on fractalkine expression. We aimed to determine the fractalkine expression in human umbilical vein endothelial cell （HUVEC） stimulated by tumor necrosis factor （TNF）-α and the effect of aspirin intervention.
Methods Six of 8 HUVEC groups received either different concentrations of aspirin （0.02, 0.2, 1.0, 5.0 mmol/L） or 40 μmol/L pyrrolidinecarbodithioc acid （PDTC） or 0.5 μmol/L NS-398. The other two groups were negative control and positive control （TNF-α-stimulated）. After being incubated for 24 hours, cells of the 8 groups except the negative control one were stimulated with TNF-α （4 ng/ml） for another 24 hours. After that, the cells were collected for RNA isolation and protein extraction.
Results Both mRNA and protein expressions of fractalkine in HUVEC were upregulated by 4 ng/ml TNF-α stimulation. Aspirin inhibited fractalkine expression in a dose-dependent manner at mRNA and protein levels. Nuclear factor-kappa B inhibitor, PDTC, effectively decreased the fractalkine expression. Fractalkine expression was not influenced by COX-2 selective inhibitor NS-398. COX-1 protein expression was not changed by either TNF-α stimulation or aspirin, PDTC, NS-398 intervention. Both mRNA and protein expression of COX-2 in HUVEC were upregulated by 4 ng/ml TNF-α stimulation. Aspirin decreased COX-2 expression in a dose-dependent manner at mRNA and protein levels.
Conclusions TNF-α-stimulated fractalkine expression is suppressed by aspirin in a dose-dependent manner through the nuclear factor-kappa B p65 pathway.     

Protective effects of erythropoietin pretreatment on myocardium with hypoxia／reoxygenation injury in rats

To establish the rat model with myocardial hypoxia/reoxygenation (H/R) injury, and investigate the protective effect of EPO pretreatment on the myocardium. Methods: Sixty male adult Wistar rats were randondv divided into 3 groups: control group, H/R group, and EPO group, 20 in each group. The rats in EPO group accepted injection of 5000 U/kg recombinant human erythropoietin (RHuEPO) through vein, and the other rats accepted the injection of the same volume of saline. Twenty-four hours after the injection, rats in the EPO and H/R groups were put into the hypoxia environment for 12h and then returned to the nonnoxic environment for 2 h, and then the samples of blood and myocardium were collected. Serum myocardial enzyme activity, apoptosis, ultrastructure, myocardial MDA contents, EPO receptor (EPOR) expression in cardiac myocytes and cardiac functions were tested. Results: EPOR expression was positive in cardiac myocytes of adult rat according to the result of immunohistochemitry assayng. Compared to those in H/R group, rats in EPO group presented lighter injury of myocardial ultrastructure, the reduction of serum myocardial erzyme activity, inhibition of apoptosis, the better recovery of cardiac functions, and the less production of oxygen-derived free radicals. Conclusion: Adult rat cardiac myocytes could express EPOR, and EPO pretreatment produced protective effects on myocardium with H/R injury.     

Impairment of Myocardial and Skeletal Mitochondria in Mice with Viral Myocarditis and Their Correlation

In order to investigate the impairment of mitochondrial membrane phospholipid local- ization and DNA3867 (mtDNA3867) deletion and the correlation between cardiac and skeletal muscle cells in mice with viral myocarditis, 50 BALB/c mice were divided into two groups randomly. In ex- perimental group (n=40), the mice were intraperitoneally injected with 0.1 mL Eagle liquid with CVB3 (TCID50=108), while in the control group (n=10), the mice were subjected to equal volume of Eagle liquid. The impairment of mitochondrial membrane phospholipid localization and mtDNA3867 deletion rate of cardiac and skeletal muscle were detected separately at day 3, 11 and 24 after injec- tion. The correlation of mitochondrial membrane phospholipid localization and mtDNA3867 deletion rate between cardiac and skeletal muscle cells cells was analyzed using Spearman method. At the day 3 after injection, in both cardiac and skeletal muscle cells, mtDNA3867 deletion rate was significantly higher in experimental group than in control group (P<0.05), but the localization of mitochondrial membrane phospholipid showed no difference between two groups (P>0.05). At day 11 after injec- tion, the mtDNA3867 deletion rate of both cells in experimental group was increased to the peak level (P<0.05), and the impairment of mitochondrial membrane phospholipid localization of both cells also increased markedly in experimental group as compared with control group (P>0.05). At the day 24 after injection, the impairment of mitochondrial membrane phospholipid localization and mtDNA3867 deletion of both cells showed a recovery tendency, but still severer than those at the day 3 after injec- tion (P<0.05). The impairment of mitochondrial membrane phospholipid localization and mtDNA3867 deletion were consistent and synchronistic between cardiac and skeletal muscle cells, and showed good correlations (P<0.05). The impairment of mitochondria plays an important role in the patho- genesis of viral myocarditis, and the skeletal muscle cells might act as a peripheral "window" to re- flect the mitochondrial damage of cardiac myocytes.     

Dynamic changes in myocardial matrix metalloproteinase activity in mice with viral myocarditis

Background Matrix metalloproteinases (MMPs) are the major regulators of collagen degradation involved in the pathogenesis of several diseases of the heart. The purpose of this study was to investigate the dynamic changes in myocardial MMP activity in mice with viral myocarditis (VM), the relationship between MMP activity and both cardiac function and the quantity of myocardial collagen, and the role MMPs playing in the pathological lesions of VM.Methods Sixty-five six-week-old male DBA/2 mice were divided into two groups. Mice in the infected group (n=50) were inoculated intraperitoneally with 0.14 ml of Coxsackievirus B3 (CVB3, Nancy strain). Control mice (n=15) were inoculated intraperitoneally with 0.14 ml of Eagle’s medium. Eight infected mice and three control mice were sacrificed on each of days 3, 7, 10, 21 and 30 after inoculation. MMP activity was measured on an SDS-PAGE substrate gel embedded with type Ⅰ gelatin (zymography). Echocardiographic studies were performed under anesthesia with 3% chloralhydrate administered intraperitoneally (0.01 ml/g-0.015 ml/g). Cardiac systolic function indices, such as peak velocity of the aorta (Vp), flow velocity integral of the aorta (Vi), ejection fraction (EF), and fractional shortening (FS) were determined by echocardiography. Histological cross sections of the hearts were stained with hematoxylin-eosin and myocardial histopathological scores were determined under an optical microscope. The amount of myocardial collagen was measured by means of hydroxyproline quantification. Results In virus-infected mice, both MMP-2 and MMP-9 activities were significantly higher than in control mice, reaching a peak on day 10 (P&lt;0.01). On day 10, cardiac systolic function indices (EF, FS, Vp, and Vi) were all significantly lower compared both to other stages following viral inoculation and to the control group (P&lt;0.05). In the acute stage, the amount of myocardial collagen in mice with VM was not significantly different from normal control mice (P&gt;0.05). However, the amount of myocardial collagen in infected mice at the recovery stage (on days 21 and 30) was significantly greater than those of the control mice. MMP-2 and MMP-9 activities positively correlated with myocardial histopathological scores (r=0.801,0.821, P&lt;0.01) and negatively correlated with Vp (r=-0.649, -0.683, P&lt;0.01) and Vi (r=-0.711, -0.755, P&lt;0.01). However, Vp negatively correlated with myocardial histopathological scores (r=-0.756, P&lt;0.01).Conclusions In mice with VM, the activities of myocardial MMP-2 and MMP-9 increase significantly during the acute stage, and the total quantity of myocardial collagen increases by the time of recovery. These changes are associated with myocardial interstition remodeling and cardiac dysfunction. MMP activity is an important reference marker for myocardial pathological lesions and can be used to evaluate the severity of myocardial interstitial damage and cardiac dysfunction.