Interleukin-1β-induced pancreatitis promotes pancreatic ductal adenocarcinoma via B lymphocyte–mediated immune suppression
Ryota Takahashi, Marina Macchini, Masaki Sunagawa, Zhengyu Jiang, Takayuki Tanaka, Giovanni Valenti, Bernhard W. Renz, Ruth A. White, Yoku Hayakawa, C. Benedikt Westphalen, Yagnesh Tailor, Alina C. Iuga, Tamas A. Gonda, Jeanine M. Genkinger, Kenneth P. Olive, Timothy C. Wang
Abstract
Objective Long-standing chronic pancreatitis is an established risk factor for pancreatic ductal adenocarcinoma (PDAC). Interleukin-1β (IL-1β) has been associated in PDAC with shorter survival. We employed murine models to investigate the mechanisms by which IL-1β and chronic pancreatitis might contribute to PDAC progression. Design We crossed LSL- Kras +/G12D ; Pdx1 -Cre (KC) mice with transgenic mice overexpressing IL-1β to generate KC-IL1β mice, and followed them longitudinally. We used pancreatic 3D in vitro culture to assess acinar-to-ductal metaplasia formation. Immune cells were analysed by flow cytometry and immunohistochemical staining. B lymphocytes were adoptively transferred or depleted in Kras-mutant mice. B-cell infiltration was analysed in human PDAC samples. Results KC-IL1β mice developed PDAC with liver metastases. IL-1β treatment increased Kras +/G12D pancreatic spheroid formation. CXCL13 expression and B lymphocyte infiltration were increased in KC-IL1β pancreata. Adoptive transfer of B lymphocytes from KC-IL1β mice promoted tumour formation, while depletion of B cells prevented tumour progression in KC-IL1β mice. B cells isolated from KC-IL1β mice had much higher expression of PD-L1, more regulatory B cells, impaired CD8 + T cell activity and promoted tumorigenesis. IL-35 was increased in the KC-IL1β pancreata, and depletion of IL-35 decreased the number of PD-L1 + B cells. Finally, in human PDAC samples, patients with PDAC with higher B-cell infiltration within tumours showed significantly shorter survival. Conclusion We show here that IL-1β promotes tumorigenesis in part by inducing an expansion of immune-suppressive B cells. These findings point to the growing significance of B suppressor cells in pancreatic tumorigenesis.