ABSTRACT
Objective:To investigate the expression profile of IL-36 family members in patients with coronary atherosclerotic heart disease (CAHD) and to assess the regulatory effects of exogenous IL-36 on CD8 + T cell function in CAHD patients. Methods:Twenty controls and 82 CAHD patients including 31 with stable angina pectoris (SAP), 27 with unstable angina pectoris (UAP) and 24 with acute myocardial infarction (AMI) were enrolled in this study. Anti-coagulant peripheral blood samples were collected. Plasma and peripheral blood mononuclear cells were isolated. The levels of IL-36α, IL-36β, IL-36γ and IL-36 receptor antagonist (IL-36RA) in plasma were measured by ELISA. CD8 + T cells were enriched. The expression of IL-36 receptor subunits at mRNA level was semi-quantified by real time PCR. Flow cytometry was used to detect the expression of programmed death-1 (PD-1), cytotoxic T lymphocytes associated protein-4(CTLA-4) and lymphocyte-activation gene-3 (LAG-3) in CD8 + T cells. Levels of periforin, granzyme B, granulysin, IFN-γ and TNF-α in the culture supernatants of CD8 + T cells were measured by ELISA. Purified CD8 + T cells from controls and AMI patients were stimulated with recombinant human IL-36RA. Changes in the expression of immune checkpoint molecules and the secretion of cytotoxic molecules and cytokines after IL-36RA stimulation were analyzed. One-way analysis of variance or paired t-test was used for statistical analysis. Results:There were no significant differences in plasma IL-36α, IL-36β or IL-36γ level between the control, SAP, UAP and AMI groups ( P>0.05). Plasma IL-36RA level was significantly down-regulated in the AMI group as compared with that in the control, SAP and UAP groups[(1 159.57±297.83) pg/ml vs (1 773.47±754.29) pg/ml, (1 600.12±740.48) pg/ml and (1 578.72±720.42) pg/ml; P<0.05]. The expression of IL-1 receptor 6 (IL-1R6) and IL-1 receptor accessory protein (IL-1RAcP) at mRNA level, the expression of PD-1 and CTLA-4, and the secretion of IFN-γ and TNF-α by CD8 + T cells showed no significant differences between the four groups ( P>0.05). Periforin, granzyme B and granulysin levels secreted by CD8 + T cells of the AMI group were significantly higherthan those of the control, SAP and UAP groups ( P<0.05). In the control group, recombinant human IL-36RA stimulation did not affect the expression of immune checkpoint molecule or the secretion of cytotoxic molecules and cytokines by CD8 + T cells ( P>0.05). In the AMI group, the percentage of PD-1 + CD8 + T cells increased after recombinant human IL-36RA stimulation ( P=0.033), but no significant change in the percentage of CTLA-4 + CD8 + T cells was observed ( P=0.288). Moreover, recombinant human IL-36RA stimulation suppressed the CD8 + T cells of AMI patients to secrete periforin, granzyme B and granulysin ( P<0.05), but not affect the secretion of IFN-γ and TNF-α ( P>0.05). Conclusions:The reduced IL-36RA level in AMI patients might induce the enhancement of CD8 + T cell activity by promoting CD8 + T cells to secrete cytotoxic molecules, which was involved in the immunopathogenesis of AMI.