CD73-generated extracellular adenosine promotes resolution of neutrophil-mediated tissue injury and restrains metaplasia in pancreatitis.

Pancreatitis is currently the leading cause of gastrointestinal hospitalizations in the US. This condition occurs in response to abdominal injury, gallstones, chronic alcohol consumption or, less frequently, the cause remains idiopathic. CD73 is a cell surface ecto-5'-nucleotidase that generates extracellular adenosine, which can contribute to resolution of inflammation by binding adenosine receptors on infiltrating immune cells. We hypothesized genetic deletion of CD73 would result in more severe pancreatitis due to decreased generation of extracellular adenosine. CD73 knockout (CD73-/- ) and C57BL/6 (wild type, WT) mice were used to evaluate the progression and response of caerulein-induced acute and chronic pancreatitis. In response to caerulein-mediated chronic or acute pancreatitis, WT mice display resolution of pancreatitis at earlier timepoints than CD73-/- mice. Using immunohistochemistry and analysis of single-cell RNA-seq (scRNA-seq) data, we determined CD73 localization in chronic pancreatitis is primarily observed in mucin/ductal cell populations and immune cells. In murine pancreata challenged with caerulein to induce acute pancreatitis, we compared CD73-/- to WT mice and observed a significant infiltration of Ly6G+, MPO+, and Granzyme B+ cells in CD73-/- compared to WT pancreata and we quantified a significant increase in acinar-to-ductal metaplasia demonstrating sustained metaplasia and inflammation in CD73-/- mice. Using neutrophil depletion in CD73-/- mice, we show neutrophil depletion significantly reduces metaplasia defined by CK19+ cells per field and significantly reduces acute pancreatitis. These data identify CD73 enhancers as a potential therapeutic strategy for patients with acute and chronic pancreatitis as adenosine generation and activation of adenosine receptors is critical to resolve persistent inflammation in the pancreas.

Radiofrequency Ablation Remodels the Tumor Microenvironment and Promotes Neutrophil-Mediated Abscopal Immunomodulation in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) presents a 5-year overall survival rate of 11%, despite efforts to improve clinical outcomes in the past two decades. Therapeutic resistance is a hallmark of this disease, due to its dense and suppressive tumor microenvironment (TME). Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) is a promising local ablative and potential immunomodulatory therapy for PDAC. In this study, we performed RFA in a preclinical tumor-bearing KrasG12D; Trp53R172H/+; Pdx1:Cre (KPC) syngeneic model, analyzed local and abscopal affects after RFA and compared our findings with resected PDAC specimens. We found that RFA reduced PDAC tumor progression in vivo and promoted strong TME remodeling. In addition, we discovered tumor-infiltrating neutrophils determined abscopal effects. Using imaging mass cytometry, we showed that RFA elevated dendritic cell numbers in RFA-treated tumors and promoted a significant CD4+ and CD8+ T-cell abscopal response. In addition, RFA elevated levels of programmed death-ligand 1 (PD-L1) and checkpoint blockade inhibition targeting PD-L1 sustained tumor growth reduction in the context of RFA. This study indicates RFA treatment, which has been shown to increase tumor antigen shedding, promotes antitumor immunity. This is critical in PDAC where recent clinical immunotherapy trials have not resulted in substantial changes in overall survival.