Bioinformatics Multivariate Analysis Determined a Set of Phase-Specific Biomarker Candidates in a Novel Mouse Model for Viral Myocarditis
Background—Myocarditis is an inflammatory disease of the cardiac muscle and is mainly caused by viral infections. Viral myocarditis has been proposed to be divided into three phases; the acute viral phase, the subacute immune phase, and the chronic cardiac remodeling phase. Although individualized therapy should be applied depending on the phase, no clinical or experimental studies have found biomarkers that distinguish between the three phases. Theiler's murine encephalomyelitis virus (TMEV) belongs to the genus Cardiovirus, and can cause myocarditis in susceptible mouse strains.
Methods and Results—Using this novel model for viral myocarditis induced with TMEV, we conducted multivariate analysis including echocardiography, serum troponin and viral RNA titration, and microarray to identify the biomarker candidates that can discriminate the three phases. Using C3H mice infected with TMEV on 4, 7, and 60 days post infection (dpi), we conducted bioinformatics analyses, including principal component analysis (PCA) and k-means clustering of microarray data, since our traditional cardiac and serum assays, including two-way comparison of microarray data, did not lead to the identification of a single biomarker. PCA separated heart samples clearly between the groups of 4, 7, and 60 dpi. Representative genes contributing to the separation were as follows: 4 and 7 dpi, innate immunity-related genes, such as Irf7, and Cxcl9; 7 and 60 dpi, acquired immunity-related genes, such as Cd3g and H2-Aa; and cardiac remodeling-related genes, such as Mmp12 and Gpnmb.
Conclusions—Sets of molecules, not single molecules, identified by unsupervised PCA, were found to be useful as phase-specific biomarkers.
- picornavirus infections
- computational biology
- transcriptome profiles
- interferon-induced protein
- systems biology
- Received January 7, 2014.
- Revision received May 5, 2014.
- Accepted May 29, 2014.