Background: CD100 is an immune semaphorin family member that highly expressed on T cells, which take part in the development of acute myocardial infarction (AMI). Matrix metalloproteinases (MMPs) are important mediators for membrane-bound CD100 (mCD100) shedding from T cells to generate soluble CD100 (sCD100), which has immunoregulatory effect on T cells. The aim of this study was to investigate modulatory role of CD100 on CD8+ T cell activity in AMI patients.
Methods: Peripheral sCD100 and MMP-2 level, as well as mCD100 level on T cells was assessed in patients with stable angina pectoris (SAP), unstable angina pectoris (UAP), and AMI. The regulatory function of MMP-2 on mCD100 shedding, sCD100 formation, and cytotoxicity of CD8+ T cells was analyzed in direct and indirect contact co-culture system.
Results: AMI patients had higher peripheral sCD100 and lower mCD100 expression on CD8+ T cells in comparison with SAP, UAP, and controls. CD8+ T cells in AMI patients showed elevated direct cytotoxicity, enhanced cytokine production, and increased perforin/granzyme B secretion. Recombinant sCD100 stimulation promoted cytolytic function of CD8+ T cells in controls and AMI patients. Furthermore, AMI patients also had elevated circulating MMP-2 level. Recombinant MMP-2 stimulation induced mCD100 shedding from CD8+ T cells and sCD100 generation, resulting in enhancement of CD8+ T cell cytotoxicity in AMI patients.
Conclusion: Up-regulation of MMP-2 might contribute to elevation of mCD100 shedding and sCD100 formation, leading to increased cytotoxicity CD8+ T cells in AMI patients.
Keywords: Acute myocardial infarction; CD100; Immunoregulation; T lymphocytes.