Dendritic Cells Promote Pancreatic Viability in Mice With Acute Pancreatitis

Abstract

Background & Aims Acute pancreatitis increases morbidity and mortality from organ necrosis by mechanisms that are incompletely understood. Dendritic cells (DCs) can promote or suppress inflammation, depending on their subtype and context. We investigated the roles of DC in development of acute pancreatitis. Methods Acute pancreatitis was induced in CD11c.DTR mice using caerulein or L-arginine; DCs were depleted by administration of diphtheria toxin. Survival was analyzed using Kaplan-Meier analysis. Results Numbers of MHC II+CD11c+DC increased 100-fold in pancreas of mice with acute pancreatitis, to account for nearly 15% of intra-pancreatic leukocytes. Intra-pancreatic DC acquired an immune phenotype in mice with acute pancreatitis; they expressed higher levels of MHC II and CD86 and increased production of interleukin-6, membrane cofactor protein (MCP)-1, and tumor necrosis factor (TNF)-α. However, rather than inducing an organ-destructive inflammatory process, DC were required for pancreatic viability; the exocrine pancreas died in mice that were depleted of DC and challenged with caerulein or L-arginine. All mice with pancreatitis that were depleted of DC died from acinar cell death within 4 days. Depletion of DC from mice with pancreatitis resulted in neutrophil infiltration and increased levels of systemic markers of inflammation. However, the organ necrosis associated with depletion of DC did not require infiltrating neutrophils, activation of NF-κB, or signaling by mitogen-activated protein kinase or TNF-α. Conclusions DC are required for pancreatic viability in mice with acute pancreatitis and might protect organs against cell stress.

Toll-like receptor 7 regulates pancreatic carcinogenesis in mice and humans

“…Bone marrow chimeric animals were created by irradiating mice (9 Gy) followed by i.v. bone marrow transfer (1 × 10 7 cells) from nonirradiated donors as we previously described (67). Chimeric mice were used in experiments 7 weeks later.…”

“…injections of caerulein (50 μg/kg) for 2-4 consecutive days. Alternatively, twice-daily administration of l-arginine (4 g/kg; Sigma-Aldrich) for 2 days was used to induce mild acute pancreatic injury, as we described previously (67), with dose modifications.…”

“…To isolate mononuclear cells from the pancreas or spleen, organs were harvested via postmortem laparotomy and processed using both mechanical and enzymatic digestion with Collagenase IV (Sigma-Aldrich), as we described previously (67,68). Cell surface marker analysis was performed by flow cytometry using the FACS Calibur (Beckman Coulter) after incubating 5 × 10 5 cells with 1 μg of anti-FcγRIII/II antibody (2.4G2, Fc block; Monoclonal Antibody Core Facility, SloanKettering Institute) and then labeling with 1 μg of FITC-, PE-, PerCP-, or APC-conjugated antibodies directed against B220 (RA3-6B2), CD3ε (17A2), CD4 (RM4-5), CD8α (53-6.7), CD11b (M1/70), CD11c (HL3), CD19 (1D3), CD34 (4H11), CD45 (30-F11), CD133 (315-2C11), CD146 (P1H12), F4/80 (BM8), and Gr1 (RB6-8C5) (all eBiosciences or BioLegend).…”

“…Cell surface marker analysis was performed by flow cytometry using the FACS Calibur (Beckman Coulter) after incubating 5 × 10 5 cells with 1 μg of anti-FcγRIII/II antibody (2.4G2, Fc block; Monoclonal Antibody Core Facility, SloanKettering Institute) and then labeling with 1 μg of FITC-, PE-, PerCP-, or APC-conjugated antibodies directed against B220 (RA3-6B2), CD3ε (17A2), CD4 (RM4-5), CD8α (53-6.7), CD11b (M1/70), CD11c (HL3), CD19 (1D3), CD34 (4H11), CD45 (30-F11), CD133 (315-2C11), CD146 (P1H12), F4/80 (BM8), and Gr1 (RB6-8C5) (all eBiosciences or BioLegend). Gating strategies for leukocyte subsets was as described previously (67)(68)(69). To determine TLR7 expression, cells were fixed, permeabilized, and stained using an mAb directed against TLR7 (IMG-581A; Imgenex).…”

“…PanIN lesions were graded using previously established criteria (72). Quantifications were performed by examining 10 high-power fields (HPFs) per pancreas, as described previously (67). The percentage of Ki67 + ductal cells as a fraction of all ductal cells was determined by manual count.…”