Nocardia Rubra Cell Wall Skeleton Up-Regulates T Cell Subsets and Inhibits PD-1/PD-L1 Pathway to Promote Local Immune Status of Patients With High-Risk Human Papillomavirus Infection and Cervical Intraepithelial Neoplasia

The Nocardia rubra cell wall skeleton (Nr-CWS) for external use is an immune enhancer, which has been widely used in human cervix diseases such as cervical erosion, but the mechanism of Nr-CWS enhancing immunity is still unclear. The purpose of this study was to explore the effect and mechanism of Nr-CWS on the local immune status of cervical tissue in patients with high-risk human papillomavirus (HR-HPV) infection and cervical precancerous lesion, cervical intraepithelial neoplasia (CIN). The recruited patients with HR-HPV infection and CIN were treated with Nr-CWS. The specimens were taken from these patients before and after local application of Nr-CWS respectively. The normal control specimens were tested simultaneously. Serial section analysis of immunohistochemistry and co-expression analysis were performed to characterize populations of T cells and the expressions of programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1). The levels of cytokines in local cervical tissue were also detected. Nr-CWS significantly increased T cells including CD4(+), CD8(+) T cells, and reduced the expression of PD-L1 in the patients’ local cervical tissues. Co-expression analyses showed that the proportions of PD-1(+)CD4(+) cells in CD4(+) T cells and PD-1(+)CD8(+) cells in CD8(+) T cells decreased after Nr-CWS application. Furthermore, the increase in the number of immune cells was accompanied by increased pro-inflammatory cytokines interleukin-12 (IL-12), interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and decreased suppressive cytokine IL-10. The results indicate that Nr-CWS, as an immunotherapeutic agent for HR-HPV infection and CIN, plays an immune promoting role related to the upregulation of T cell subsets and the inhibition of PD-1/PD-L1 pathway.