OBJECTIVEto observe the alteration of T helper cells 17(Th17) in mice with acute viral myocarditis (VMC) induced by coxsackie virus B3 (CVB3), explore the role of Th17 in mice VMC.

METHODSCVB3 or PBS was peritoneally injected to Balb/c male mice. Pathological scores were determined in hematoxylin-eosin stained sections and flow cytometric analysis was used to evaluate the frequencies of Th17 subsets in CD4(+) T cells on 7, 14, 21, 28 and 42 days after virus injection.

RESULTSthere were significant difference of the pathological scores between the VMC mice and the control ones (P < 0.05). The pathological scores of 7 d VMC subgroup were higher (1.8 ± 0.5) than those of 0 d VMC subgroup, and the scores of 14 d subgroup were highest (2.8 ± 0.4) among the six subgroup of VMC mice, and then showed a decline tendency from 21 d group. Statistical difference of the proportion of Th17 cells were seen between the VMC and controls on different time points (P < 0.05). When compared with the 0 d VMC subgroup the proportion of spleen Th17 cells increased in 7 d VMC subgroup [(2.23 ± 0.89)%], and peaked on 28 d [(5.00 ± 0.81)%]. The results of Th17 proportion were lower than those of the 28 d subgroup.

CONCLUSIONSour data show that differentiated Th17 cells might be involved in the inflammation process of CVB3 induced VMC in mice.

Animals ; Coxsackievirus Infections ; immunology ; pathology ; Enterovirus ; Male ; Mice ; Mice, Inbred BALB C ; Myocarditis ; immunology ; pathology ; virology ; Myocardium ; pathology ; Th17 Cells ; immunology

OBJECTIVEViral myocarditis (VM) is one of the most common acquired myocardial diseases in children. However, its pathogenesis is not clear. Recent studies indicate that the cytotoxicity mediated by cytotoxic T lymphocyte (CTL) plays an important role in the development of myocardial injury involved in VM. Apoptosis mediated by Fas/FasL pathway is an essential mechanism of target cells damage by CTL. In this study, the authors investigated the regulatory effects of neutralizing anti-Fas ligand (anti-FasL) antibody on apoptosis and caspase-3 expression in experimental coxsackievirus B3 myocarditis and the role of the CTL mediated apoptosis in myocardium through Fas/FasL pathway in the development of VM.

METHODSA total of 80 BALB/c mice were used in the experiments. They were divided randomly into the following groups: normal control group (Gr1), CVB3 control group (Gr2), IgG control group (Gr3) and anti-FasL antibody therapy group (Gr4). The mice in Gr2, Gr3 and Gr4 were inoculated with 0.15 ml of TCID(50) 10(9)/ml coxsackie virus B3 (CVB3) and the mice in Gr1 with 0.15 ml of Eagle reagent. The mice in Gr3 and Gr4 were inoculated with IgG (0.1 mg/kg) and FasL antibody (0.1 mg/kg) on days 0 and days 3 after inoculation (p.i.), respectively. Eight mice in each group were sacrificed on day 10 p.i. Histopathological studies and terminal transferase-mediated dUTP-biotin nick end labeling (TUNEL) assays were used to quantify inflammation, necrosis and apoptosis in myocardium. The expression of active caspase-3 in myocardium was determined by immunohistochemistry. Caspase-3 mRNA and CVB3 mRNA were analyzed by reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS(1) Caspase-3 activation and apoptosis were seen in the myocardium of mice with myocarditis. They had a significantly positive correlation with the changes of myocardial histopathologic scores (r = 0.81, P < 0.05; r = 0.73, P < 0.05). (2) The pathologic scores, average percentages of apoptotic cardiomyocytes, expression of active caspase-3 (protein and mRNA) and expression of CVB3 mRNA in myocardium of mice in Gr4, were significantly reduced compared to those in the myocardium of mice in Gr2 (P < 0.01, P < 0.01, P < 0.01, P < 0.01, and P < 0.05, respectively) and Gr3 (P < 0.01, P < 0.01, P < 0.05, P < 0.01, and P < 0.05, respectively).

CONCLUSIONMyocytic apoptosis is a key mechanism responsible for myocardial damage in viral myocarditis. Anti-FasL antibody can effectively reduce expression of active caspase-3 protein and mRNA, viral replication, cardiomyocytic apoptosis and myocardial injury in the experimental CVB3 myocarditis.

Animals ; Antibodies, Neutralizing ; therapeutic use ; Apoptosis ; Caspase 3 ; immunology ; Coxsackievirus Infections ; drug therapy ; immunology ; Enterovirus B, Human ; physiology ; Fas Ligand Protein ; immunology ; Mice ; Mice, Inbred BALB C ; Myocarditis ; drug therapy ; immunology ; virology ; Myocardium ; immunology ; pathology ; Virus Replication

OBJECTIVETo observe the alteration of interleukin-17 and interferon-γ double positive cells (IL-17(+)/IFN-γ(+) cells) in mice with coxsackie virus B3 (CVB3) induced acute viral myocarditis (VMC).

METHODSVMC was induced in male Balb/c mice by peritoneal injection of CVB3. Control mice received PBS injection. At 0, 1, 2, 3, 4 and 6 weeks after injection, pathological scores were determined on hematoxylin-eosin stained heart sections and flow cytometric analysis was performed to evaluate the percent of IL-17(+)/IFN-γ(+) cells among CD4(+) T cells.

RESULTSCompared to control mice, the pathological scores of VMC mice were higher on CVB3 infection week 1 (1.8 ± 0.5), peaked on week 2 (2.8 ± 0.5) and declined thereafter. However, the proportion of IL-17(+)/IFN-γ(+) cells remained steadily at a low level throughout the observation period and was similar between VMC and control mice.

CONCLUSIONSOur data shows that IL-17(+)/IFN-γ(+) cells might not be involved in the inflammation process of CVB3 induced VMC mice model.

Animals ; Coxsackievirus Infections ; immunology ; pathology ; Disease Models, Animal ; Enterovirus ; Interferon-gamma ; metabolism ; Interleukin-17 ; metabolism ; Male ; Mice ; Mice, Inbred BALB C ; Myocarditis ; immunology ; pathology ; virology ; Myocardium ; pathology ; Th17 Cells ; immunology ; metabolism

Endomyocardial biopsy often fails to show myocardial inflammation for patients with clinically suspected myocarditis. The serum isoforms of troponin T (cTnT) level is a very sensitive marker of myocardial injury and it is elevated even in the absence of myocardial inflammation. We investigated the correlations for myocardial injury, virus titers and inflammation in acute viral infection. Using the murine coxsackievirus group B3 (CVB3) myocarditis model, the histopathologic findings and virus titers in mouse hearts were compared with the serum cTnT levels measured by ELISA at various time points. Viable virus titers in the hearts peaked at 3 days after infection (8.22+/-0.13 log10 PFU/100 mg of heart); they decreased at day 7 and no viable virus was detected from day 14. Myocardial inflammation was minimal at day 3, peaked at day 7 and markedly decreased at day 14. The individual serum TnT levels were significantly increased at day 3 (7.37+/-1.46 ng/ml), persisted to day 7 (0.73+/-0.08 ng/ml), and normalized at day 14. Serum cTnT levels were correlatable with virus titers in the heart (r=0.744, P <0.01), but the serum cTnT levels were not correlated with the degrees of inflammation. Using the less myocarditic strain of CVB3, similar relationships were observed between the changes for the serum cTnT levels and the heart virus titers. During the course of viral infection, myocardial injury precedes the pathologic evidence of inflammation, and the elevated cTnT levels provide evidence of myocardial injury even in the absence of any histologic findings of myocarditis.
Acute Disease ; Animals ; Coxsackievirus Infections/*pathology ; Enterovirus B, Human/isolation & purification/pathogenicity/*physiology ; Female ; Heart/*virology ; Hela Cells ; Humans ; Inflammation/*immunology ; Mice ; Mice, Inbred BALB C ; Myocardial Infarction/immunology/*pathology ; Myocarditis/immunology/pathology/*virology ; *Myocardium/immunology/pathology ; Research Support, Non-U.S. Gov't ; Troponin T/blood ; Virus Replication