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Activated protein C targets CD8+ dendritic cells to reduce the mortality of endotoxemia in mice.

ABSTRACT: Activated protein C (aPC) therapy reduces mortality in adult patients with severe sepsis. In mouse endotoxemia and sepsis models, mortality reduction requires the cell signaling function of aPC, mediated through protease-activated receptor-1 (PAR1) and endothelial protein C receptor (EPCR; also known as Procr). Candidate cellular targets of aPC include vascular endothelial cells and leukocytes. Here, we show that expression of EPCR and PAR1 on hematopoietic cells is required in mice for an aPC variant that mediates full cell signaling activity but only minimal anticoagulant function (5A-aPC) to reduce the mortality of endotoxemia. Expression of EPCR in mature murine immune cells was limited to a subset of CD8+ conventional dendritic cells. Adoptive transfer of splenic CD11chiPDCA-1- dendritic cells from wild-type mice into animals with hematopoietic EPCR deficiency restored the therapeutic efficacy of aPC, whereas transfer of EPCR-deficient CD11chi dendritic cells or wild-type CD11chi dendritic cells depleted of EPCR+ cells did not. In addition, 5A-aPC inhibited the inflammatory response of conventional dendritic cells independent of EPCR and suppressed IFN-gamma production by natural killer-like dendritic cells. These data reveal an essential role for EPCR and PAR1 on hematopoietic cells, identify EPCR-expressing dendritic immune cells as a critical target of aPC therapy, and document EPCR-independent antiinflammatory effects of aPC on innate immune cells.

SUBMITTER: Kerschen E

PROVIDER: S-EPMC2929901 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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Activated protein C targets CD8+ dendritic cells to reduce the mortality of endotoxemia in mice.

Kerschen Edward E Hernandez Irene I Zogg Mark M Jia Shuang S Hessner Martin J MJ Fernandez Jose A JA Griffin John H JH Huettner Claudia S CS Castellino Francis J FJ Weiler Hartmut H

The Journal of clinical investigation 20100816 9

Activated protein C (aPC) therapy reduces mortality in adult patients with severe sepsis. In mouse endotoxemia and sepsis models, mortality reduction requires the cell signaling function of aPC, mediated through protease-activated receptor-1 (PAR1) and endothelial protein C receptor (EPCR; also known as Procr). Candidate cellular targets of aPC include vascular endothelial cells and leukocytes. Here, we show that expression of EPCR and PAR1 on hematopoietic cells is required in mice for an aPC v ...[more]

PMID: 20714108

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Project description:BACKGROUND & AIMS:Pancreatic ductal adenocarcinoma (PDAC) is characterized by a prominent desmoplastic microenvironment that contains many different immune cells. Activated pancreatic stellate cells (PSCs) contribute to the desmoplasia. We investigated whether distinct stromal compartments are differentially infiltrated by different types of immune cells. METHODS:We used tissue microarray analysis to compare immune cell infiltration of different pancreaticobiliary diseased tissues (PDAC, ampullary carcinoma, cholangiocarcinoma, mucinous cystic neoplasm, chronic inflammation, and chronic pancreatitis) and juxtatumoral stromal (<100 ?m from tumor) and panstromal compartments. We investigated the association between immune infiltrate and patient survival times. We also analyzed T-cell migration and tumor infiltration in LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mice and the effects of all-trans retinoic acid (ATRA) on these processes. RESULTS:Juxtatumoral compartments in PDAC samples from 2 independent groups of patients contained increased numbers of myeloperoxidase(+) and CD68(+) cells compared with panstromal compartments. However, juxtatumoral compartments of PDACs contained fewer CD8(+), FoxP3(+), CD56(+), or CD20(+) cells than panstromal compartments, a distinction absent in ampullary carcinomas and cholangiocarcinomas. Patients with PDACs that had high densities of CD8(+) T cells in the juxtatumoral compartment had longer survival times than patients with lower densities. In KPC mice, administration of ATRA, which renders PSCs quiescent, increased numbers of CD8(+) T cells in juxtatumoral compartments. We found that activated PSCs express cytokines, chemokines, and adhesion molecules that regulate T-cell migration. In vitro migration assays showed that CD8(+) T cells, from patients with PDAC, had increased chemotaxis toward activated PSCs, which secrete CXCL12, compared with quiescent PSCs or tumor cells. These effects could be reversed by knockdown of CXCL12 or treatment of PSCs with ATRA. CONCLUSIONS:Based on studies of human PDAC samples and KPC mice, activated PSCs appear to reduce migration of CD8(+) T cells to juxtatumoral stromal compartments, preventing their access to cancer cells. Deregulated signaling by activated PSCs could prevent an effective antitumor immune response.

Project description:ObjectiveDendritic cells (DCs) have long been recognized as potential therapeutic targets of rheumatoid arthritis (RA). Increasing evidence has showed that DCs are capable of suppressing autoimmunity by expanding FoxP3? regulatory T cells (T(reg)), which in turn exert immunosuppression by increasing TGF?-1. In the SKG mice, activated DC prime autoreactive T cells causing autoantibody production and an inflammatory arthritic response. Recently, we reported that CC-chemokine receptor-2 deficient (Ccr2?/?) mice had impaired DCs migration and reduced CD8?? DCs in the C57Bl/6J mice strain and that these mice were more susceptible to collagen antibody-induced arthritis (CAIA), compared to wild type mice. To examine the mechanism by which DCs contribute to the increased susceptibility of arthritis in Ccr2?/? mice, we tested the hypothesis that CD8?? DCs are protective (tolerogenic) against autoimmune arthritis by examining the role of CD8?? DCs in Ccr2?/? and SKG mice.MethodsTo examine the mechanism by which DCs defects lead to the development of arthritis, we used two murine models of experimental arthritis: collagen-induced arthritis (CIA) in DBA1/J mice and zymosan-induced arthritis in SKG mice. DBA1/J mice received recombinant fms-like tyrosine kinase 3 ligand (Flt3L) injections to expand endogenous DCs populations or adoptive transfers of CD8?? DCs.ResultsFlt3L-mediated expansion of endogenous CD8?? DCs resulted in heightened susceptibility of CIA. In contrast, supplementation with exogenous CD8?? DCs ameliorated arthritis in Ccr2?/? mice and enhanced TGF?1 production by T cells. Furthermore, SKG mice with genetic inactivation of CCR2 did not affect the numbers of DCs nor improve the arthritis phenotype.ConclusionCD8?? DCs were tolerogenic to the development of arthritis. CD8?? DCs deficiency heightened the sensitivity to arthritis in Ccr2?/? mice. Ccr2 deficiency did not alter the arthritic phenotype in SKG mice suggesting the arthritis in Ccr2?/? mice was T cell-independent.

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Activated protein C targets CD8+ dendritic cells to reduce the mortality of endotoxemia in mice.

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Activated protein C targets CD8+ dendritic cells to reduce the mortality of endotoxemia in mice.

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