Detection of transforming growth factor beta 1 of normal dogs and dogs with degenerative mitral valve disease

Degenerative mitral valve disease (DMVD) is the most common cause of acquired cardiac diseases in adult small and medium sized dogs. Transforming growth factor beta 1 (TGF-β1), a cytokine controlling extracellular matrix homeostasis within valves is thought to be involved in valve degenerative process. The expression of TGF-β1 protein was reported markedly increase in the DMVD valves. The first objective of this study was to measure the concentration of TGF-β1 in plasma of normal and DMVD dogs by ELISA technique. The second objective was to compare TGF-β1 mRNA expression between normal and DMVD dogs from mitral valve (MV) samples by RT-PCR. Comparison of plasma TGF-β1 concentrations was performed with Mann Whitney U test. P-value less than 0.05 was considered statistically significant. The result showed no statistical difference in median of plasma TGF-β1 concentrations between 22 normal (1.14(0.94-1.33) ng/mL) and 27 DMVD (1.21(0.92-1.32) ng/mL) dogs. The expression of TGF-β1 mRNA from 10 MV (normal = 5, DMVD = 5) samples showed positive band. For positive bands, the mean ± SD of TGF-β1 and GAPDH band intensity ratio was compared between normal and DMVD dogs assessed by independent t-test. The result between normal (0.55 ± 0.07) and DMVD (0.95 ± 0.06) valves were significantly different (p < 0.05). In conclusion, the concentration of TGF-β1 protein is very low in circulation. It is possible that cells within mitral valves are the major source of TGF-β1 in dogs affected with DMVD.