Pseudostellaria heterophylla protein hydrolysate has been reported to be a potential nutraceutical supplement to strengthen the immune system. A specific peptide from P. heterophylla protein hydrolysate with proliferation promotion effect on spleen lymphocytes was purified by RP-HPLC. The amino acid sequence of the peptide was determined to be RGPPP, with molecular weight of 522.29 Da. 100 μg/mL of RP-5 achieved the highest stimulation index of 1.27 on spleen lymphocytes and activated RAW264.7 cells resulting in up-regulating tumor necrosis factor-α (TNF-α) secretion to 827.24 pg/mL and elevating pinocytosis rate to 123.81%. Results of western-blot and siRNA experiments indicated that RP-5 activated nuclear factor-κB (NF-κB) signaling pathway through combining to TLR2 expressed on RAW264.7 cells surface. Furthermore, TNF-α secretion increased by RP-5 could be decreased to 401.68 pg/mL by pyrrolidine dithiocarbamate or BAY11-7082. These findings further the research progress of peptide with immunomodulatory activity and its action mechanism.

据报道，太子参蛋白质水解物是增强免疫系统的潜在营养补充品。太子参的一种特定肽通过RP-HPLC纯化对脾淋巴细胞具有增殖促进作用的蛋白水解产物。确定该肽的氨基酸序列为RGPPP，分子量为522.29 Da。100μg/ mL RP-5对脾淋巴细胞和激活的RAW264.7细胞达到最高刺激指数1.27，从而将肿瘤坏死因子-α（TNF-α）分泌上调至827.24 pg / mL，并将胞吞作用速率提高至123.81％。Western印迹和siRNA实验结果表明，RP-5通过与RAW264.7细胞表面表达的TLR2结合而激活了核因子-κB（NF-κB）信号通路。此外，吡咯烷二硫代氨基甲酸酯或BAY11-7082可将RP-5增加的TNF-α分泌降低至401.68 pg / mL。