Neoplastic pancreatic epithelial cells are widely believed to die via Caspase 8-dependant apoptotic cell death and chemotherapy is thought to further promote tumor apoptosis1. Conversely, disruption of apoptosis is a basic modality cancer cells exploit for survival2,3. However, the role of necroptosis, or programmed necrosis, in pancreatic ductal adenocarcinoma (PDA) is uncertain. There are a multitude of potential inducers of necroptosis in PDA including ligation of TNFR1, CD95, TRAIL receptors, Toll-like receptors, ROS, and Chemotherapeutics4,5. Here we report that the principal components of the necrosome, RIP1 and RIP3, are highly expressed in PDA and are further upregulated by chemotherapy. Blockade of the necrosome in vitro promoted cancer cell proliferation and induced an aggressive oncogenic phenotype. By contrast, in vivo RIP3 deletion or RIP1 inhibition was protective against oncogenic progression and was associated with the development of a highly immunogenic myeloid and T cell infiltrate. The immune-suppressive tumor microenvironment (TME) associated with intact RIP1/RIP3 signaling was in-part contingent on necroptosis-induced CXCL1 expression whereas CXCL1 blockade was protective against PDA. Moreover, we found that cytoplasmic SAP130 was expressed in PDA in a RIP1/RIP3-dependent manner, and Mincle – its cognate receptor – was upregulated in tumor-infiltrating myeloid cells. Mincle ligation by SAP130 promoted oncogenesis whereas Mincle deletion was protective and phenocopied the immunogenic reprogramming of the TME characteristic of RIP3 deletion. Cellular depletion experiments suggested that whereas inhibitory macrophages promote tumorigenesis in PDA, they lose their immune-suppressive effects in the context of RIP3 or Mincle deletion. As such, T cells which are dispensable to PDA progression in hosts with intact RIP3 or Mincle signaling become reprogrammed into indispensable mediators of anti-tumor immunity in absence of RIP3 or Mincle. Our work describes parallel networks of necroptosis-induced CXCL1 and Mincle signaling which critically promote macrophage-induced adaptive immune suppression enabling PDA progression.

Background & Aims The role of radiation therapy in the treatment of patients with pancreatic ductal adenocarcinoma (PDA) is controversial. Randomized controlled trials investigating the efficacy of radiation therapy in patients with locally advanced unresectable PDA have reported mixed results, with effects ranging from modest benefit to worse outcome, compared with control therapies. We investigated whether radiation causes inflammatory cells to acquire an immune-suppressive phenotype that limits the therapeutic effects of radiation on invasive PDAs and accelerates progression of pre-invasive foci. Methods We investigated the effects of radiation in p48Cre;LSL-KrasG12D (KC) and p48Cre;LSLKrasG12D;LSL-Trp53R172H (KPC) mice, as well as in C57BL/6 mice with orthotopic tumors grown from FC1242 cells derived from KPC mice. Some mice were given neutralizing antibodies against macrophage colony stimulating factor 1 (CSF1 or MCSF) or F4/80. Pancreata were exposed to doses of radiation ranging from 2–12 Gy and analyzed by flow cytometry. Results Pancreata of KC mice exposed to radiation had a higher frequency of advanced pancreatic intraepithelial lesions and more foci of invasive cancer than pancreata of unexposed mice (controls); radiation reduced survival time by more than 6 months. A greater proportion of macrophages from invasive and pre-invasive pancreatic tumors had an immune-suppressive, M2-like phenotype, compared with control mice. Pancreata from mice exposed to radiation had fewer CD8+ T cells than controls and greater numbers of CD4+ T cells of T-helper 2 and T-regulatory cell phenotypes. Adoptive transfer of T cells from irradiated PDA to tumors of control mice accelerated tumor growth. Radiation induced production of MCSF by PDA cells. An antibody against MCSF prevented radiation from altering the phenotype of macrophages in tumors, increasing the anti-tumor T-cell response and slowing tumor growth. Conclusions Radiation exposure causes macrophages in PDAs of mice to acquire an immune-suppressive phenotype and reduce T-cell mediated anti-tumor responses. Agents that block MCSF prevent this effect, allowing radiation to have increased efficacy in slowing tumor growth.

Cancer cachexia is a debilitating condition characterized by a combination of anorexia, muscle wasting, weight loss, and malnutrition. This condition affects an overwhelming majority of patients with pancreatic cancer and is a primary cause of cancer-related death. However, few, if any, effective therapies exist for both treatment and prevention of this syndrome. In order to develop novel therapeutic strategies for pancreatic cancer cachexia, appropriate animal models are necessary. In this study, we developed and validated a syngeneic, metastatic, murine model of pancreatic cancer cachexia. Using our model, we investigated the ability of transforming growth factor beta (TGF-β) blockade to mitigate the metabolic changes associated with cachexia. We found that TGF-β inhibition using the anti-TGF-β antibody 1D11.16.8 significantly improved overall mortality, weight loss, fat mass, lean body mass, bone mineral density, and skeletal muscle proteolysis in mice harboring advanced pancreatic cancer. Other immunotherapeutic strategies we employed were not effective. Collectively, we validated a simplified but useful model of pancreatic cancer cachexia to investigate immunologic treatment strategies. In addition, we showed that TGF-β inhibition can decrease the metabolic changes associated with cancer cachexia and improve overall survival.

Summary Dectin-1 is a C-type lectin receptor critical in anti-fungal immunity but Dectin-1 has not been linked to regulation of sterile inflammation or oncogenesis. We found that Dectin-1 expression is upregulated in hepatic fibrosis and liver cancer. However, Dectin-1 deletion exacerbates liver fibro-inflammatory disease and accelerates hepatocarcinogenesis. Mechanistically, we found that Dectin-1 protects against chronic liver disease by suppressing TLR4 signaling in hepatic inflammatory and stellate cells. Accordingly, Dectin-1−/− mice exhibited augmented cytokine production and reduced survival in LPS-mediated sepsis whereas Dectin-1 activation was protective. We showed that Dectin-1 inhibits TLR4 signaling by mitigating TLR4 and CD14 expression which are regulated by Dectin-1-dependent M-CSF expression. Our study suggests that Dectin-1 is an attractive target for experimental therapeutics in hepatic fibrosis and neoplastic transformation. More broadly, our work deciphers critical cross-talk between pattern recognition receptors and implicates a role for Dectin-1 in suppression of sterile inflammation, inflammation-induced oncogenesis, and LPS-mediated sepsis.

Phlegmonous gastritis is a rare and progressive fatal condition that affects the mucosa and submucosa of the gastric wall. It can be localized or diffuse, affecting the entire stomach. It usually presents with upper gastrointestinal symptoms, such as nausea, vomiting, and hematemesis, along with systemic symptoms, including fever, chills, and fatigue. Risk factors include mucosal injury, surgery, hypoacidity, and immunosuppression that can be seen in human immunodeficiency virus (HIV)-positive or alcoholic patients. We present a case of phlegmonous gastritis which developed after a laparoscopic sleeve gastrectomy. The patient presented with epigastric pain, nausea, and chills two months post-sleeve gastrectomy. The diagnosis was made with computed tomography (CT) scan of the abdomen. She was managed successfully with CT-guided drainage and antibiotics.