Montoya Megan, Collins Sara A, Chuntova Pavlina, Patel Trishna S, Nejo Takahide, Yamamichi Akane, Kasahara Noriyuki, Okada Hideho
Department of Neurological Surgery, University of California San Francisco, San Francisco, California, USA.
Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California, USA.
Neuro Oncol. 2024 Dec 5;26(12):2272-2287. doi: 10.1093/neuonc/noae149.
Glioblastoma (GBM) has a highly immunosuppressive tumor immune microenvironment (TIME), largely mediated by myeloid-derived suppressor cells (MDSCs). Here, we utilized a retroviral replicating vector (RRV) to deliver Interferon Regulatory Factor 8 (IRF8), a master regulator of type 1 conventional dendritic cell (cDC1) development, in a syngeneic murine GBM model. We hypothesized that RRV-mediated delivery of IRF8 could "reprogram" intratumoral MDSCs into antigen-presenting cells and thereby restore T-cell responses.
Effects of RRV-IRF8 on survival and tumor growth kinetics were examined in the SB28 murine GBM model. The immunophenotype was analyzed by flow cytometry and gene expression assays. We assayed functional immunosuppression and antigen presentation by ex vivo T-cell-myeloid co-culture.
Intratumoral injection of RRV-IRF8 in mice bearing intracerebral SB28 glioma significantly suppressed tumor growth and prolonged survival. RRV-IRF8 treated tumors exhibited significant enrichment of cDC1s and CD8+ T-cells. Additionally, myeloid cells derived from RRV-IRF8 tumors showed decreased expression of the immunosuppressive markers Arg1 and IDO1 and demonstrated reduced suppression of naïve T-cell proliferation in ex vivo co-culture, compared to controls. Furthermore, DCs from RRV-IRF8 tumors showed increased antigen presentation compared to those from control tumors. In vivo treatment with azidothymidine (AZT), a viral replication inhibitor, showed that IRF8 transduction in both tumor and non-tumor cells is necessary for survival benefit, associated with a reprogrammed, cDC1- and CD8 T-cell-enriched TIME.
Our results indicate that reprogramming of glioma-infiltrating myeloid cells by in vivo expression of IRF8 may reduce immunosuppression and enhance antigen presentation, achieving improved tumor control.
胶质母细胞瘤（GBM）具有高度免疫抑制性的肿瘤免疫微环境（TIME），主要由髓系来源的抑制性细胞（MDSCs）介导。在此，我们利用逆转录病毒复制载体（RRV）在同基因小鼠GBM模型中递送干扰素调节因子8（IRF8），它是1型传统树突状细胞（cDC1）发育的主要调节因子。我们假设RRV介导的IRF8递送可以将肿瘤内的MDSCs“重编程”为抗原呈递细胞，从而恢复T细胞反应。
在SB28小鼠GBM模型中检测RRV-IRF8对生存和肿瘤生长动力学的影响。通过流式细胞术和基因表达分析对免疫表型进行分析。我们通过体外T细胞-髓系共培养来检测功能性免疫抑制和抗原呈递。
在携带脑内SB28胶质瘤的小鼠中瘤内注射RRV-IRF8可显著抑制肿瘤生长并延长生存期。RRV-IRF8治疗的肿瘤显示cDC1和CD8 + T细胞显著富集。此外，与对照组相比，来自RRV-IRF8肿瘤的髓系细胞显示免疫抑制标志物Arg1和IDO1的表达降低，并且在体外共培养中对幼稚T细胞增殖的抑制作用减弱。此外，与对照肿瘤相比，RRV-IRF8肿瘤的树突状细胞显示出增加的抗原呈递。用叠氮胸苷（AZT）进行体内治疗，AZT是一种病毒复制抑制剂，结果表明肿瘤细胞和非肿瘤细胞中的IRF8转导对于生存获益是必需的，这与重编程的、富含cDC1和CD8 T细胞的TIME相关。
我们的结果表明，通过体内表达IRF8对胶质瘤浸润性髓系细胞进行重编程可能会降低免疫抑制并增强抗原呈递，从而实现更好的肿瘤控制。
