| First Author | Metzger P | Year | 2020 |
| Journal | Cancer Immunol Immunother | Volume | 69 |
| Issue | 10 | Pages | 2101-2112 |
| PubMed ID | 32448983 | Mgi Jnum | J:296746 |
| Mgi Id | MGI:6469772 | Doi | 10.1007/s00262-020-02605-9 |
| Citation | Metzger P, et al. (2020) Systemic but not MDSC-specific IRF4 deficiency promotes an immunosuppressed tumor microenvironment in a murine pancreatic cancer model. Cancer Immunol Immunother 69(10):2101-2112 |
| abstractText | Pancreatic ductal adenocarcinoma is characterized by a strong immunosuppressive network with a dense infiltration of myeloid cells including myeloid-derived suppressor cells (MDSC). Two distinct populations of MDSC have been defined: polymorphonuclear MDSC (PMN-MDSC) and monocytic MDSC (M-MDSC). Several factors influence the development and function of MDSC including the transcription factor interferon regulatory factor 4 (IRF4). Here, we show that IRF4 deficiency accelerates tumor growth and reduces survival, accompanied with a dense tumor infiltration with PMN-MDSC and reduced numbers of CD8(+) T cells. As IRF4 has been described to modulate myeloid cell development and function, particularly of PMN-MDSC, we analyzed its role using MDSC-specific IRF4 knockout mice with the Ly6G or LysM knock-in allele expressing Cre recombinase and Irf4(flox). In GM-CSF-driven bone marrow cultures, IRF4 deficiency increased the frequency of MDSC-like cells with a strong T cell suppressive capacity. Myeloid (LysM)-specific depletion of IRF4 led to increased tumor weight and a moderate splenic M-MDSC expansion in tumor-bearing mice. PMN cell (Ly6G)-specific depletion of IRF4, however, did not influence tumor progression or MDSC accumulation in vivo in accordance with our finding that IRF4 is not expressed in PMN-MDSC. This study demonstrates a critical role of IRF4 in the generation of an immunosuppressive tumor microenvironment in pancreatic cancer, which is independent of IRF4 expression in PMN-MDSC. |
