Search

Recent transcriptomic-based analysis of diffuse large B cell lymphoma (DLBCL) has highlighted the clinical relevance of lymph node (LN) fibroblast and tumor-infiltrating lymphocyte (TIL) signatures within the tumor microenvironment (TME). However, the immunomodulatory role of fibroblasts in lymphoma remains unclear. Here, by studying human and mouse DLBCL-LNs, we identify the presence of an aberrantly remodeled fibroblastic reticular cell (FRC) network, expressing elevated fibroblast activated protein (FAP). RNA-sequencing analyses reveal that exposure to DLBCL reprograms key immunoregulatory pathways in FRCs, including a switch from homeostatic to inflammatory chemokine expression and elevated antigen presentation molecules. Functional assays show that DLBCL-activated FRCs (DLBCL-FRCs) hinder optimal TIL and chimeric antigen receptor T cell (CAR-T) migration. Moreover, DLBCL-FRCs inhibited CD8+ TIL cytotoxicity in an antigen-specific manner. Notably, the interrogation of patient LNs with imaging mass cytometry identified distinct environments differing in their CD8+ TIL-FRC composition and spatial organization that associated with survival outcomes. We further demonstrate the potential to target inhibitory FRCs to rejuvenate interacting TILs. Co-treating organotypic cultures with FAP-targeted immunostimulatory drugs and a bispecific antibody (glofitamab) augmented anti-lymphoma TIL cytotoxicity. Together, our study reveals an immunosuppressive role of FRCs in DLBCL, with implications for immune evasion, disease pathogenesis and optimizing immunotherapy for patients.

Supplementary methods. Supplementary table S1: STR analysis of cell lines. Supplementary Table S2: Oligonucleotid sequences of primers. Supplementary Table S3: Mutational analyses of NR4A1 and NR4A3. Supplementary Table S4: Correlation between NR4A1 and pro-apoptotic genes in human cancer. Supplementary Table S5: Correlation between NR4A3 and pro-apoptotic genes in human cancer. Supplementary Figure S1: NR4A1 mRNA expression analysis in Karpas-422, SuDHL4, RI-1 and U2392 after treatment with 10microM TG or DMSO. Supplementary Figure S2: NR4A1 mRNA expression analysis in Karpas-422, RI-1 and U2392 after treatment with 10microM BF175 or DMSO. Supplementary Figure S3: Positive correlation in mRNA expression of NR4A1 and NR4A3 and pro-apoptotic genes in patients with aggressive lymphomas.

Nuclear orphan receptor NR4A1 exerts an essential tumor suppressor function in aggressive lymphomas. In this study, we investigated the hypothesized contribution of the related NR4A family member NR4A3 to lymphomagenesis. In aggressive lymphoma patients, low expression of NR4A3 was associated with poor survival. Ectopic expression or pharmacological activation of NR4A3 in lymphoma cell lines led to a significantly higher proportion of apoptotic cells. In a mouse NSG xenograft model of lymphoma (stably transduced SuDHL4 cells), NR4A3 expression abrogated tumor growth, compared with vector control and uninduced cells that formed massive tumors. Transcript analysis of four different aggressive lymphoma cell lines overexpressing either NR4A3 or NR4A1 revealed that apoptosis was driven similarly by induction of BAK, Puma, BIK, BIM, BID, and Trail. Overall, our results showed that NR4A3 possesses robust tumor suppressor functions of similar impact to NR4A1 in aggressive lymphomas. Cancer Res; 77(9); 2375–86. ©2017 AACR.