Induction of injury to endothelium of pulmonary artery due to entero superantigen by up regulation of lymphocyte chemokine receptor 5

Abstract

To observe the injurious effect of T cell activated by Staphylococcus enterotoxin B (SEB) on human pulmonary artery endothelial cell (HPAEC) and explore its possible mechanism. HPAEC was cocultured with SEB-activated T cells supernatant, and the secretion of chemotactic factors from HPAEC was examined. The Transwell inserts was used in chemoattraction assays. After HPAECs were cocultured with T cells and 10 ng/ml SEB for 3 days, HPAEC damage was monitored by microscopy and the terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay. Three kinds of tested chemokines showed a time dependent increase in all supernatant of HPAEC incubated with different concentrations of T cells. After 72 hours, the monocyte chemoattractant protein 1 (MCP 1, ng/ml) in 1×10(-2) , 1×10(-1), 1×10(0) T cell supernatant groups was 1.240±0.103, 4.200±0.305, 6.500±0.500, respectively, macrophage inflammatory protein 1α (MIP 1α, ng/ml) was 0.210±0.015, 0.287±0.012, 0.531±0.037, respectively , and Rantes (ng/ml) was 1.420±0.074, 7.634±0.630, 15.700±1.300, respectively. Rantes presented a two phase secretion mode: in early 6 hours it increased swiftly, but relatively slow at 12, 24, 48, 72 hours. T cell adherent to polycarbonate membrane increased after SEB stimulation in superantigen group compared with control group without SEB stimulation (86.38±14.50 vs. 16.50±2.50, P<0.01). When 10 ng/ml SEB-activated T cell was cocultured with HPAEC, more of originally suspended cultured T cells adhered to HPAEC monolayer [(15.50±1.08)% vs. (1.60±0.22)%, PP<0.01], whereas the cell adhesion ratio decreased markedly in 1 μg/ml Met Rantes group [(4.39±0.66)%, PP<0.01). FACs test of HPAEC adherent T cell showed lymphocyte chemokine receptor 5 (CCR5)/CD4 and CCR5/CD8 increased over 2.5 folds and 2.8 folds compared with 100 ng/ml SEB-activated T cell. Cell death rate of HPAEC was increased when cocultured with SEB-activated T cell in superantigen group compared with HPAEC normal incubation group [(32.50±4.50)% vs. (3.50±0.50)%, P<0.01]. Increased chemoattraction and adherence of SEB-activated T cells to HPAEC could damage HPAEC; this effect was possibly due to up regulation of CCR5 on T cell.