Cells were stimulated with different concentrations of GPC81–95 peptide (1, 5 and 10 μg/ml) and cultured in the presence or absence of TLR1–9 ligands and the expression
levels of membrane-bound LAP (TGF-β1) were analysed using flow cytometry. None of TLR ligands, including LPS, increased the expression of LAP (TGF-β1) on GPC81–95 peptide-stimulated T cells (data not shown). Anti-CD3 antibody induces LAP (TGF-β1) on T cells and suppresses inflammatory condition in a TGF-β1-dependent manner.3 Moreover, it has been shown that vascular endothelial growth factor (VEGF) induces TGF-β1.20 To compare the ability of these ligands with GPC81–95 to induce LAP (TGF-β1), PBMCs were stimulated with different concentrations of anti-CD3 antibody, VEGF, VIP, PMA/ionomycin, staphylococcal enterotoxin B, purified protein Tamoxifen derivative or GPC81–95 and the percentage of LAP (TGF-β1)+ CD4+ T cells was analysed using flow cytometry. GPC81–95 and anti-CD3 antibody (1 and 5 μg/ml) induced LAP (TGF-β1) on CD4 T cells,
whereas VEGF, VIP, PMA/ionomycin, staphylococcal enterotoxin B and purified protein derivative did not induce LAP (TGF-β1) expression (Fig. 3e). Apoptotic cells are known to produce TGF-β1.21 To determine whether check details peptide-induced LAP (TGF-β) expression on CD4+ T cells is the result of T-cell apoptosis, CD4+ Jurkat T cells were treated with different concentrations of GPC81–95 peptide (5–30 μg/ml). The percentages of cell death and early apoptosis were analysed by 7-AAD and annexin Baricitinib V staining, respectively, 5 and 24 hr after exposure. GPC81–95 did not induce cell death or apoptosis in Jurkat T cells (Fig. 4a). All the assays were performed in triplicate and the results were confirmed in two independent experiments. Moreover, peptide-induced LAP (TGF-β1)+ CD4+ Jurkat T cells were 7-AAD− annexin
V−, demonstrating that these cells are not dead or dying (Fig. 4b,c). The PBMCs isolated from healthy donors were cultured with GPC81–95 or an irrelevant peptide (AFP365–373) and then stimulated with 10 ng/ml LPS. The concentrations of different pro-inflammatory cytokines (TNF-α, IL-1β, IL-6 and RANTES) were measured in the supernatant after 24 hr (Fig. 5a). Treatment of the cells with an irrelevant peptide (AFP365–373) did not alter the concentration of pro-inflammatory cytokines in comparison with non-treated cells or cells treated with PBS diluents (data not shown), suggesting that the irrelevant peptide has no inhibitory effect. In contrast, GPC81–95-treatment inhibited the production of TNF-α but not the production of IL-1β, IL-6 or RANTES (Fig. 5a). The average percentages of inhibition from four independent experiments are shown in Fig. 5(b), demonstrating that TNF-α is the only pro-inflammatory cytokine measured that was consistently inhibited by GPC81–95 treatment (AFP365–373 was used as an irrelevant peptide). Inhibition of TNF-α by GPC81–95 treatment was seen over a range of LPS doses (Fig. 5c).