Immunomodulatory effects of the pentapeptide YGSRS on human peripheral-blood mononuclear cells.

CONTEXT The pentapeptide YGSRS is originated from coffee bean, while its pharmacological features have little been examined. OBJECTIVES We investigated the effects of YGSRS on proliferation, cytokine production and CD4+ CD25+ Foxp3+ regulatory T (Treg) cell frequency of human peripheral blood mononuclear cells (PBMCs) activated by T-cell mitogen. MATERIALS AND METHODS The effects of YGSRS on T-cell mitogen-activated PBMCs were assessed by WST assay procedures. Concentrations of Th1/Th2/Th17 cytokines in the PBMCs culture medium were analyzed with beads-array procedures followed by analysis with flow cytometry. The CD4+ CD25+ Foxp3+ Treg cells in mitogen-activated PBMCs were stained with fluorescence-labeled specific antibodies followed by flow cytometry. RESULTS YGSRS at 1-10,000 ng/ml (1.56-15,600 nM) has a tendency to promote the mitogen-activated proliferation of PBMCs, but the effects were not statistically significant. YGSRS affect the production of tumor necrosis factor (TNF) α, interleukin (IL)-4, IL-6 and IL-10 from the activated PBMCs, and statistically significant increase in the concentrations of IL-6 and IL-10 in the medium were observed at 1-1000 ng/ml (1.56-1560 nM) (p < 0.05). YGSRS has a tendency to decrease the frequency of Treg cells in the activated PBMCs, but the difference was not statistically significant. DISCUSSION AND CONCLUSIONS The data suggest that the pentapeptide YGSRS affects the production of several types of cytokines from activated human peripheral T cells, which may modulate Th2 type immunity.