3.5. HMGB1 A Box inhibited T cell infiltration partially through binding of CXCR4 on T cells.
T cells express CXCR4 like macrophages. Given that CXCR4 mediates HMGB1-induced macrophage migration and infiltration into SN, we wanted to explore whether CXCR4 also mediates T cell migration and infiltration during PD and whether HMGB1 A Box also combines with CXCR4 to play a competitive inhibitory role. Firstly, mouse spleen CD3+ T cells were isolated and cultured, and HMGB1 A Box was added to the culture for 6h. Cell immunofluorescence staining and co-immunoprecipitation data showed that HMGB1 A Box could bind to CXCR4 on T cells (Fig. 6A, B). To evaluate whether targeting CXCR4 on the surface of T cells inhibits T cell migration, spleen CD3+ T cells from GFP mice were isolated, treated with HMGB1 A Box or CXCR4 neutralizing antibody in vitro , washed extensively, and then transfused into wild-type mice. The PD model was then induced with MPTP. Finally, immunofluorescence results in mouse SN showed that compared with mice reinfused with control CD3+ T cells, HMGB1 A Box and CXCR4 neutralizing antibody-treated CD3+ T cells transfused mice had significantly less GFP+CD3+ T cells infiltrated in the SN (Fig. 6D), and more GFP+CD3+ T cells remained in the periphery (Fig. 6C). These data suggest that CXCR4 of T cells also mediates T cell infiltration into the SN in MPTP induced PD model, and this process can be directly inhibited by the binding of HMGB1 A Box to CXCR4.