Abstract 3239: Cancer-associated fibroblasts induce immunosuppressive macrophages in head and neck squamous cell carcinoma

Abstract

Abstract Background Cancer-associated fibroblasts (CAFs) are one of main elements in the tumor microenvironment (TME). Among the innate and adaptive immune cells in the TME, tumor-associated macrophages (TAMs) are particularly abundant and play a protumoral role. However, an interaction between CAFs and TAMs in head and neck squamous cell carcinoma (HNSCC) still remains unclear. In the present study, we investigated whether CAFs skewed macrophage function toward the immune suppressive phenotype. Materials and Methods In vitro assay: CAFs were prepared from surgical tissue of HNSCC patients, and culture supernatants of CAFs were collected. Using this supernatants and peripheral blood mononuclear cells collected from healthy donors, immunological interactions between CAFs and TAMs was investigated. In vivo assay: The immunohistochemistry (IHC) of 73 patients with HNSCC was performed. Anti-α-smooth muscle actin, CD68, and CD163 antibodies were used to identify CAFs and TAMs, respectively. The relationship between immunohistochemical parameters and clinical parameters was evaluated. Results The expression levels of CD68, CD163, CD14, CD80, CD86, and HLA-G were up-regulated in CD14+ cells co-cultured with the supernatants of CAFs (CAF-educated cells) compared with control cells. Moreover, the gene expressions of ARG1, IL6, IL10 and TGFB1 were also increased in CAF-educated cells. The CAF-educated cells suppressed T-cell proliferation more intensively than control cells, and neutralization of TGF-β and IL-10 led to significant restoration of T-cell proliferation. In IHC, the intensity of CAFs correlated with the number of CD68-positive macrophages, especially with CD163-positive macrophages. It also correlated with several clinical parameters such as lymphatic invasion, vascular invasion, nodal status, tumor stages and recurrence rate. Moreover, the high intensity of CAFs correlated with poor PFS and OS. The high intensity of CAFs and M2 macrophage infiltration were independent prognostic factors of PFS and OS in HNSCC. Conclusion The present study suggests that CAFs can induce an immunosuppressive phenotype of macrophages and contribute to establishing the immunosuppressive networks in TME, resulting poor prognosis in HNSCC patients. Citation Format: Hideyuki Takahashi, Koichi Sakakura, Kazuaki Chikamatsu. Cancer-associated fibroblasts induce immunosuppressive macrophages in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3239.