Significance of detection of enterovirus RNA in myocardial tissues by reverse transcription-polymerase chain reaction

Detection of enterovirus RNA in postoperative thyroid tissue specimens

CONTEXT

Autoimmune thyroiditis is a very common disease. A genetic predisposition and environmental factors such as viruses are thought to contribute to the development of autoimmune thyroiditis. Enteroviruses, which are involved in other autoimmune diseases, are attractive candidates.

OBJECTIVE

To investigate the presence of enteroviral genome sequences in postoperative thyroid tissues with lymphocytic infiltration, a common histological feature of thyroiditis.

SUBJECTS AND METHODS

Postoperative thyroid specimens collected prospectively from 86 patients were blindly frozen at -80 degrees C. The presence of EV genome sequences in the samples was blindly investigated by real-time RT-PCR. Clinical data, histological findings and levels of anti-TPO antibodies were collected.

RESULTS

EV-RNA detection was positive (up to 36 cycles) or weakly positive (37-39 cycles) in 22 out of 86 patients (25%). EV-RNA (positive or weakly positive signal) was detected in 5 out of 27 (18.5%) thyroid specimens with lymphocytic infiltration, and in 17 out of 59 (29%) thyroid specimens without lymphocytic infiltration (P = 0.4). No correlation was observed between EV-RNA detection in thyroid and the presence of anti-TPOAb. EV-RNA was detected in 3 out of 11 patients histologically diagnosed as thyroiditis (27.3%) and in 18 out of 74 patients (24.3%) with thyroid tumours (multinodular goitre, adenoma and carcinoma) (P = 0.5) and in one patient with a normal thyroid.

CONCLUSION

EV-RNA can be detected in thyroid tissue from patients with various thyroid diseases, but there is no relationship between the presence of EV-RNA and thyroiditis. Further studies are needed to clarify the role of EV in thyroid diseases.

Idiopathic dilated cardiomyopathy. Elastic parallel element dysfunction as a physiopathological hypothesis for ventricular failure

BACKGROUND

Idiopathic dilated cardiomyopathy is a disease of unknown etiology, although the viral-immunologic pathogenesis has recently emerged as an important hypothesis. Its distinctive anatomopathologic features are: macroscopically, a great ventricular dilation with little hypertrophy, and microscopically marked diffuse interstitial fibrosis not observed in other pathologic entities with dilation. Hemodynamically, its main characteristic is a progressive loss of the systolic function, although the diastolic function is also impaired. To date it is accepted that in dilated states ventricular remodeling occurs due to sliding of fiber with a maximal sarcomere distention; it is also assumed that the ventricular dysfunction is due to a primary deficit in contractility caused by the injury and loss of myocites.

HYPOTHESIS

The aggressive agent mainly attacks the interstitial tissue, thus damaging the elastic parallel element structures. This results in a loss of absorbing power during diastole, starting a progressive dilation which results in maximum sarcomere distention, and compromises the ventricular function. The organ response is to create a new parallel element, which results in an increased fibrosis which also compromises this function.

Enteroviral genome in native hearts may influence outcome of patients who undergo cardiac transplantation

The Enterovirus may be the most common agent responsible for viral myocarditis and cardiomyopathy. Very little of the literature is available concerning the follow-up of patients who underwent transplantation with enteroviral positivity in native hearts. In the present study, 45 explanted hearts from patients who underwent orthotopic heart transplant at University of Padova were studied by reverse transcriptase (RT)-polymerase chain reaction (PCR): 27 patients had dilated cardiomyopathy (DC), 12 had ischemic cardiopathy (IC), 2 had valvular disease (VD), 2 had arrhythmogenic right ventricular cardiomyopathy (ARVC), 1 had giant cell myocarditis (GCM), and 1 had lymphocytic myocarditis (LM). Two sets of PCR primers from the highly conserved region of Enterovirus and Rhinovirus were used. Samples of both ventricles and septum were analyzed in every patients. The RT-PCR and nucleotide sequencing of amplicons were also performed on all post-transplantation follow-up biopsies in patients with Enterovirus positivity in the native heart. The viral genome was detectable in only 1 of 27 patients with DC (3%) and in 1 patient with LM. Nucleotide sequence analysis of the amplified product showed differences in nucleotide sequence of PCR samples compared with the sequence of the coxsackievirus B3 used in the current study. The patient with Enterovirus-positive DC showed a higher index of severe rejection (>3A) in the first 6 months, compared with the other patients tested. The patient with Enterovirus-positive LM died of disease recurrence 2 months after transplantation. The present study reveals a scarce presence of Enterovirus in the myocardium of patients with chronic myocardial disease. Because Enterovirus infection was predictive of a poor prognosis in these two patients, molecular studies are useful in excluding viral involvement in native hearts of transplanted patients.

Meta-analysis of the association of enteroviruses with human heart disease

The role of viruses in the genesis of both dilated cardiomyopathy (DCM) and acute myocarditis remains uncertain. Modern molecular techniques such as polymerase chain reaction (PCR) and in situ hybridisation are sensitive means of detecting viral genomic material in human myocardial tissue and may help to resolve the quest. Meta-analysis of the papers in the literature records studies of both acute myocarditis and DCM where molecular techniques were used to demonstrate enteroviruses. This review studies information from the published literature as well as statistical analysis of the cumulative molecular data relating enteroviruses to DCM, and to compare these findings with the information available on the role of enteroviruses in acute myocarditis. Twelve papers reported studies in acute myocarditis, of which 11 found higher percentages of enteroviral RNA positivity in the diseased population, giving an overall odds ratio of 4.4. Seventeen papers reported studies in DCM, with 11 recording higher positivity rates in these patients. Cumulative analysis of these data suggests an overall odds ratio of 3.8. The causative role of enteroviruses in acute myocarditis, particularly in children, is supported by meta-analysis of the available literature. The data on DCM is suggestive of an association but a proportion of the studies are negative.

Experimental CVB3-induced chronic myocarditis in two murine strains: evidence of interrelationships between virus replication and myocardial damage in persistent cardiac infection

In order to analyse the relationships between enteroviral replication and the myocardial damage at the onset of chronic cardiac infection, 2 mouse strains with different degrees of immunological competence (NMRI nu/nu, DBA/2) were infected by a myocarditic Coxsackie virus B3 (CVB3-M1) variant. At 31 days post-inoculation, plaque-forming assay, polymerase chain reaction (RT-PCR), and immunohistochemistry were carried out for detecting viruses and viral components in the myocardium. The virological findings were related to histopathological changes in the myocardium as well to the dilatation of both cardiac ventricles. Chronic myocardial lesions characterized by large fibrosis areas and interstitial inflammatory infiltrates were detected together with cardiomegalia in 52.6% (10/19) of athymic mice and in 9% (2/22) of euthymic mice. Viral replication foci were located and were found only in myocarditic cells adjacent to myocardial inflammatory lesions by immunostaining myocardial tissue sections with anti-serum to VP1 virus capsid protein. Using PCR followed by microwell capture hybridization assay, a large excess of viral positive strand RNA over negative strand was semiquantified in heart tissue from mice with chronic myocarditis, whereas approximately equal amounts of plus and minus strand RNA were detected in cases of persistent cardiac infection without chronic myocardial injuries. These findings provide evidence of the major role of viral replication in the pathogenesis of chronic murine CVB3-induced cardiomyopathy. The results indicate that the cardiac persistence of enteroviral RNAs can be observed without chronic cardiomyopathy, which could be explained by a defective viral positive RNA replication.