[Cardiac valve MCSF-1 and its receptor expression changes in Staphylococcus aureus induced infective endocarditis].

Objective: To explore the cellular immunology mechanism of infective endocarditis (IE), we investigated the effects of Staphylococcus aureus (S. aureus) on MCSF-1 and its receptor (c-fms) gene expression in cardiac valves.

Methods: Thirty-two rabbits were divided into 4 groups: mitral or tricuspid valve artificial lesions with 5 x 10(4) CFU or 5 x 10(6) CFU S. aureus injection. Control rabbits (n = 7) received 5 x 10(6) CFU S. aureus injection. IE after operation were confirmed by naked eyes and electron microscope observations. MCSF-1, c-fms in mitral and tricuspid valves were detected by RT-PCR.

Results: Twenty-six rabbits survived the operation and 14 rabbits developed IE (2 with 5 x 10(4) CFU and 12 with 5 x 10(6) CFU S. aureus injection) one day post operation. S. aureus injection alone did not induce IE. Compared to control rabbits, MCSF-1 mRNA was significantly upregulated and c-fms mRNA significantly downregulated after 5 x 10(4) CFU S. aureus injection with heart valve artificial lesion in mitral valves or tricuspid valves. MCSF-1 expression in mitral valves was further increased while remained unchanged in tricuspid valve after 5 x 10(6) CFU S. aureus injection compared to that in 5 x 10(4) CFU S. aureus injection group.

Conclusion: High dose bacterial invasion and heart valves lesion were the main factors for inducing infective endocarditis. Development of infective endocarditis was associated with valve MCSF-1/c-fms expression changes in this rabbit model.