[Effects of activated CD4+ T cell-derived exosomes on cardiac remodeling after myocardial infarction].

OBJECTIVE

To explore the role of activated CD4+ T cells in cardiac remodeling after myocardial infarction (MI).

METHODS

(1) Experiment in vitro: naive CD4+ T cells were isolated in mouse spleen, and then stimulated with plate-bound anti-CD3 and anti-CD28 for 48 hours. Exosomes isolated from the supernatant of activated CD4+ T cells were incubated with cardiac fibroblasts (CFs) for 48 hours, and then the ability of CFs proliferation, migration and differentiation were detected by cell counting kit-8 (CCK-8) assay, Transwell assay, and immunofluorescence assay. (2) Experiment in vivo: 40 male C57 mice were divided into 4 groups according to random number table method, including control group (Ctrl group), sham operation group (Sham group), MI group, and exosome treatment group (MI+Exo group), with 10 in each group. The mice model of MI was established by ligating the left anterior descending coronary artery. In MI+Exo group, 40 μg/d exosomes were injected intravenously into the tail after modeling. Cardiac function and cardiac fibrosis post-MI were assessed by echocardiography and quantitative polymerase chain reaction (qPCR) at 4th week.

RESULTS

(1) In vitro: exosomes derived from activated CD4+ T cells significantly promote CFs proliferation, migration and differentiation [proliferation ability (A value): 0.31±0.01 vs. 0.21±0.01, migration capability (cells/MP): 79.20±3.34 vs. 48.80±2.13, differentiation ability (α-smooth muscle actin, α-SMA; fluorescence intensity): 1.56±0.03 vs. 1.00±0.02, all P < 0.05]. (2) In vivo: echocardiographic analysis showed that exosomes derived from activated CD4+ T cells aggravated the deterioration of cardiac dysfunction post-MI than MI group, as indicated by left ventricular ejection fraction (LVEF) and fractional shortening (FS) decreased significantly [LVEF: 0.185±0.008 vs. 0.257±0.022, FS: (9.72±1.72)% vs. (14.08±1.08)%, both P < 0.05], left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD) increased significantly [LVEDD (mm): 5.43±0.29 vs. 4.62±0.35, LVESD (mm): 4.94±0.12 vs. 3.69±0.29, both P < 0.05]. Additionally, qPCR showed that exosomes derived from activated CD4+ T cells remarkably promoted myocardial fibrosis post-MI than MI group, as indicated by the mRNA expression of α-SMA, collagens (Col1a1, Col3a1) in MI+Exo group was significantly higher than that in MI group [α-SMA (2-ΔΔCT): 4.72±0.89 vs. 3.58±0.78, Col1a1 (2-ΔΔCT): 6.59±0.56 vs. 4.23±0.42, Col3a1 (2-ΔΔCT): 13.40±1.03 vs.4.96±0.36, all P < 0.05].

CONCLUSIONS

Activated CD4+ T cells promote cardiac remodeling following MI through transferring exosomes to CFs.