Expression of genes encoding matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in normal and diseased canine mitral valves.

The pathogenesis of canine chronic valvular disease (CVD) is not fully characterized. The present study investigates the expression of genes encoding matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in normal and diseased mitral valves (MVs). Samples from normal (n=15) or diseased (n=10) canine MVs were subject to real-time polymerase chain reaction (PCR) for quantification of mRNA encoding MMP-1, -2, -9 and -14 and TIMP-2, -3 and -4. In normal valves there was low expression of mRNA encoding MMP-2, -9 and -14 and TIMP-3. In the valves from dogs with CVD there was significantly increased transcription of mRNA encoding MMP-1 and -14 and TIMP-2, -3 and -4, but no elevation in mRNA encoding MMP-2 and -9. MMPs and TIMPs are therefore likely to be involved in extracellular matrix metabolism in normal canine MVs and there are significant alterations in the expression of genes encoding these molecules during CVD.