Experimental study on inhibition of T lymphocyte failure by Yantiao Formula through the PD-1/PD-L1 pathway in septic rats

WANG Wenqing; WANG Qing; XIONG Xudong

doi:10.3969/j.issn.1002-7386.2024.10.004

Abstract：Objective To study the effect of Yantiao Formula on the expression levels of programmed cell death protein-1(PD-1)and programmed cell death ligand-1(PD-L1)in T lymphocytes and on T lymphocyte surface of septic rats.Methods Male Sprague-Dawley(SD)rats were divided into control group,sham operation group,model group and Yantiao Formula group.The cecal ligation and puncture(CLP)method was adopted to prepare the sepsis model in rats.After 12 h,24 h,48 h and 72 h of modeling,rats were subjected to the collection of peripheral blood samples and sacrificed.The proportions of CD3+,CD4+and CD8+T cells were measured by flow cytometry.Expression levels of PD1 and PD-L1 on the surface of CD4+and CD8+cells were measured by enzyme-linked immunosorbent assay(ELISA).Results We detected the expression levels of inflammatory factor interleukin 6(IL-6)and infection indicator procalcitonin(PCT)in rats.In model group,IL-6 level peaked at 12 h and gradually decreased,and PCT peaked at 24 h and gradually decreased.In Yantiao Formula group,IL-6 level was reduced from 12 h(P＜0.05),and significantly reduced IL-6 and PCT levels were detected at 24h(P＜0.01).The proportions of CD3+,CD4+and CD8+T cells in the model group were reduced in the early stage,and bottomed at 48h(P＜0.01).In Yantiao Formula group,the proportions of CD3+,CD4+and CD8+T cells were elevated at 48 h.Increasing CD4+/CD8+was capable of regulating the activation and proliferation of T cells.Expression levels of PD1 and PD-L1 on the surface of CD4+and CD8+T cells were upregulated as early as at 24 h in the model group,and peaked at 72h(P＜0.01).The treatment of Yantiao Formula effectively inhibited PD1 and PD-L1 on the surface of CD4+and CD8+T cells as early as at 24 h,thus alleviating T lymphocyte failure.The proportion of CD4+T cells was negatively correlated with expression levels of PD1 and PD-L1 on the surface of CD4+T cells(P＜0.01),and the proportion of CD8+T cells was negatively correlated with expression levels of PD1 and PD-L1 on the surface of CD8+T cells(P＜0.01).Conclusion T lymphocyte failure of the suppressed activation and proliferation occurs in the early stage at 48 h of sepsis.Yantiao Formula improves T cell activation and proliferation in the early stage of sepsis by inhibiting the PD-1/PD-L1 pathway.