Fig. 1
From: Roles of cancer-associated fibroblasts (CAFs) in anti- PD-1/PD-L1 immunotherapy for solid cancers
The mechanism of CAFs regulating TME to affect PD-1/PD-L1 inhibitor immunotherapy. a CAFs secrete VEGF, TGF-β, CXCL12, etc., which promote Treg recruitment, migration and FOXP3+Treg differentiation. The latter promotes CD8+ T cell dysfunction by secreting IL-35 and IL-10. b CAFs secrete WnT2, etc., thereby inhibiting the anti-tumor response of DC-cell-mediated CD8+ T cells. c CAFs secrete TGF-β, MMP-1, HA, etc. to remodel ECM, increase rigidity, and prevent immune cell infiltration. d TGF-β and CLCF1 differentiate TAN into tumor-promoting types; IL-6 promotes the expression of PD-L1 by TAN, leading to the formation of immune tolerance; SDF-1α and CXCR2 promote TAN migration to tumor tissue. e CAFs produce MCP-1, IL-8, SDF-1, etc. to promote monocyte recruitment, induce TAMs to M2 phenotypic differentiation, and impair effector T cell function, and increase the expression level of PD-L1 on the surface of the TAMs, impairing its phagocytosis