Coxsackievirus B3 Infection Early in Pregnancy Induces Congenital Heart DefectsThrough Suppression of Fetal Cardiomyocyte Proliferation
AimsCoxsackievirus B (CVB), the most common cause of viral myocarditis, targets cardiomyocytes through Coxsackie and Adenovirus Receptor, which is highly expressed in the fetal heart. We hypothesized CVB3, a well-recognized culprit for viral myocarditis, can precipitate congenital heart defects (CHD), when fetal infection occurs during critical window of gestation. Methods & ResultsWe infected C57Bl/6 pregnant mice with CVB3 during serial time points in early gestation (E5, E7, E9 and E11). We used different viral titers to examine possible dose- response relationship and assessed viral loads in various fetal organs as well as kinetics of virus passage into the fetus during gestation. Provided viral exposure occurred between E7-E9, we observed characteristic features of ventricular septal defect (33.6%), abnormal myocardial architecture resembling non-compaction (23.5%), and double outlet right ventricle (4.4%) among 209 viable fetuses examined. We observed a direct relationship between viral titers, severity and incidence of CHD, with apparent predominance among female fetuses. Infected dams remained healthy; we did not observe any maternal heart or placental injury suggestive of direct viral effects on developing heart as likely cause of CHD. We examined signaling pathways in CVB3-exposed hearts using RNAseq, KEGG enrichment analysis and immunohistochemistry. Signaling proteins of the Hippo, tight junction, transforming growth factor {beta}1 and extracellular matrix proteins were the most highly enriched in CVB3-infected fetuses with VSD (log fold change >1.9, P<0.02). Moreover, cardiomyocyte proliferation was 50% lower in fetuses with VSD compared with uninfected controls. ConclusionPrenatal CVB3 infection can induce CHD, provided the infection occurs during a critical window. Alterations in myocardial proliferate capacity and consequent changes in cardiac architecture and trabeculation appear to account for the majority of observed phenotypes. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=179 HEIGHT=200 SRC="FIGDIR/small/104844v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@79d320org.highwire.dtl.DTLVardef@1419b8org.highwire.dtl.DTLVardef@1a49082org.highwire.dtl.DTLVardef@10b72bb_HPS_FORMAT_FIGEXP M_FIG C_FIG