BTK 抑制剂预处理通过下调 M2 巨噬细胞极化提高共培养体系中 DLBCL 细胞对 CAR-T 细胞的敏感性

The tumour microenvironment (TME) of relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) patients is associated with resistance of DLBCL cells to CD19 CAR-T cells. How to improve TME in DLBCL and improve the efficacy of CAR-T cell therapy remains to be further explored.

We observed the sensitivity of HBL-1/U2932 cells pretreated with BTK inhibitors (BTKi) to CAR-T cells with flow cytometry (FCM). The effect of pretreatment of BTKi on the polarisation state of alternative activated M2 macrophages was observed with FCM, real-time PCR and Western blot method. The effect of Notch1 agonist on expressions of Arg-1 protein, iNOS protein, Notch1 protein and RBP-J protein in alternative activated M2 macrophages was observed by Western blot method. Then the expression consistency of Notch-1 and RBP-J in activated M2 macrophages was observed by siRNA transfection of Notch-1. The cytotoxicity of CD19 CAR-T cells on HBL-1/U2932 cells pretreated with ibrutinib/orelabrutinib was higher than that of HBL-1/U2932 cells unpretreated with ibrutinib/orelabrutinib. Cytotoxicity of CAR-T cells to HBL-1 cells in coculture system with alternative activated M2 macrophages was very low.

This drug resistance could be reversed by replacing the M2 macrophages (M2 macrophages after 48 h pretreatment with BTKi) in coculture system. Pretreatment with BTKi could down-regulate the expression of CD206 and IL-10 in activated M2 macrophages. And pretreatment with BTKi down-regulated the expression of Arg-1 and upregulated the expression of iNOS in activated M2 macrophages.

The upregulation polarisation of M2 macrophages by Notch1 agonist could be reversed by BTKi. Expression of RBP-J protein decreased in alternative activated M2 macrophages by siRNA silencing Notch 1. Pretreatment with BTKi could down-regulate the polarisation of M2 macrophages and reverse the resistance of DLBCL cells which were cocultured with alternative activated M2 macrophages to CAR-T cells. This effect might be achieved by downregulating the Notch-RBP-J pathway.