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Adeel Rehman,
Keith C Hemmert,
Atsuo Ochi,
Mohsin Jamal,
Justin R Henning,
Rocky Barilla,
Juan P Quesada,
Constantinos P Zambirinis,
Kerry Tang,
Melvin Ego-Osuala,
Raghavendra S Rao,
Stephanie Greco,
Michael Deutsch,
Suchithra Narayan,
H Leon Pachter,
Christopher S Graffeo,
Devrim Acehan,
George Miller
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ABSTRACT: Dendritic cells (DC) are professional APCs that regulate innate and adaptive immunity. The role of fatty-acid synthesis in DC development and function is uncertain. We found that blockade of fatty-acid synthesis markedly decreases dendropoiesis in the liver and in primary and secondary lymphoid organs in mice. Human DC development from PBMC precursors was also diminished by blockade of fatty-acid synthesis. This was associated with higher rates of apoptosis in precursor cells and increased expression of cleaved caspase-3 and BCL-xL and downregulation of cyclin B1. Further, blockade of fatty-acid synthesis decreased DC expression of MHC class II, ICAM-1, B7-1, and B7-2 but increased their production of selected proinflammatory cytokines including IL-12 and MCP-1. Accordingly, inhibition of fatty-acid synthesis enhanced DC capacity to activate allogeneic as well as Ag-restricted CD4(+) and CD8(+) T cells and induce CTL responses. Further, blockade of fatty-acid synthesis increased DC expression of Notch ligands and enhanced their ability to activate NK cell immune phenotype and IFN-γ production. Because endoplasmic reticulum (ER) stress can augment the immunogenic function of APC, we postulated that this may account for the higher DC immunogenicity. We found that inhibition of fatty-acid synthesis resulted in elevated expression of numerous markers of ER stress in humans and mice and was associated with increased MAPK and Akt signaling. Further, lowering ER stress by 4-phenylbutyrate mitigated the enhanced immune stimulation associated with fatty-acid synthesis blockade. Our findings elucidate the role of fatty-acid synthesis in DC development and function and have implications to the design of DC vaccines for immunotherapy.
The Journal of Immunology 03/2013; · 5.79 Impact Factor
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Justin R Henning,
Christopher S Graffeo, Adeel Rehman,
Nina C Fallon,
Constantinos P Zambirinis,
Atsuo Ochi,
Rocky Barilla,
Mohsin Jamal,
Michael Deutsch,
Stephanie Greco,
Melvin Ego-Osuala,
Usama Bin Saeed,
Raghavendra S Rao,
Sana Badar,
Juan P Quesada,
Devrim Acehan,
George Miller
[show abstract]
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ABSTRACT: Non-alcoholic steatohepatitis (NASH) is the most common etiology of chronic liver dysfunction in the United States and can progress to cirrhosis and liver failure. Inflammatory insult resulting from fatty infiltration of the liver is central to disease pathogenesis. Dendritic cells (DC) are antigen presenting cells with an emerging role in hepatic inflammation. We postulated that DC are important in the progression of NASH. We found that intrahepatic DC expand and mature in NASH liver and assume an activated immune-phenotype. However, rather than mitigating the severity of NASH, DC depletion markedly exacerbated intrahepatic fibro-inflammation. Our mechanistic studies support a regulatory role for DC in NASH by limiting sterile inflammation via their role in clearance of apoptotic cells and necrotic debris. We found that DC limit CD8(+) T cell expansion and restrict Toll-like receptor expression and cytokine production in innate immune effector cells in NASH, including Kupffer cells, neutrophils, and inflammatory monocytes. Consistent with their regulatory role in NASH, during the recovery phase of disease, ablation of DC populations results in delayed resolution of intrahepatic inflammation and fibroplasia. Conclusion: Our findings support a role for DC in modulating NASH. Targeting DC functional properties may hold promise for therapeutic intervention in NASH. (HEPATOLOGY 2013.).
Hepatology 01/2013; · 11.66 Impact Factor
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Atsuo Ochi,
Christopher S Graffeo,
Constantinos P Zambirinis, Adeel Rehman,
Michael Hackman,
Nina Fallon,
Rocky M Barilla,
Justin R Henning,
Mohsin Jamal,
Raghavendra Rao,
Stephanie Greco,
Michael Deutsch,
Marco V Medina-Zea,
Usama Bin Saeed,
Melvin O Ego-Osuala,
Cristina Hajdu,
George Miller
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Atsuo Ochi,
Christopher S Graffeo,
Constantinos P Zambirinis, Adeel Rehman,
Michael Hackman,
Nina Fallon,
Rocky M Barilla,
Justin R Henning,
Mohsin Jamal,
Raghavendra Rao,
Stephanie Greco,
Michael Deutsch,
Marco V Medina-Zea,
Usama Bin Saeed,
Melvin O Ego-Osuala,
Cristina Hajdu,
George Miller
[show abstract]
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ABSTRACT: Pancreatic ductal adenocarcinoma is an aggressive cancer that interacts with stromal cells to produce a highly inflammatory tumor microenvironment that promotes tumor growth and invasiveness. The precise interplay between tumor and stroma remains poorly understood. TLRs mediate interactions between environmental stimuli and innate immunity and trigger proinflammatory signaling cascades. Our finding that TLR7 expression is upregulated in both epithelial and stromal compartments in human and murine pancreatic cancer led us to postulate that carcinogenesis is dependent on TLR7 signaling. In a mouse model of pancreatic cancer, TLR7 ligation vigorously accelerated tumor progression and induced loss of expression of PTEN, p16, and cyclin D1 and upregulation of p21, p27, p53, c-Myc, SHPTP1, TGF-β, PPARγ, and cyclin B1. Furthermore, TLR7 ligation induced STAT3 activation and interfaced with Notch as well as canonical NF-κB and MAP kinase pathways, but downregulated expression of Notch target genes. Moreover, blockade of TLR7 protected against carcinogenesis. Since pancreatic tumorigenesis requires stromal expansion, we proposed that TLR7 ligation modulates pancreatic cancer by driving stromal inflammation. Accordingly, we found that mice lacking TLR7 exclusively within their inflammatory cells were protected from neoplasia. These data suggest that targeting TLR7 holds promise for treatment of human pancreatic cancer.
The Journal of clinical investigation 10/2012; · 15.39 Impact Factor
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Atsuo Ochi,
Andrew H Nguyen,
Andrea S Bedrosian,
Harry M Mushlin,
Saman Zarbakhsh,
Rocky Barilla,
Constantinos P Zambirinis,
Nina C Fallon, Adeel Rehman,
Yuliya Pylayeva-Gupta,
Sana Badar,
Cristina H Hajdu,
Alan B Frey,
Dafna Bar-Sagi,
George Miller
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ABSTRACT: The transition of chronic pancreatic fibroinflammatory disease to neoplasia is a primary example of the paradigm linking inflammation to carcinogenesis. However, the cellular and molecular mediators bridging these entities are not well understood. Because TLR4 ligation can exacerbate pancreatic inflammation, we postulated that TLR4 activation drives pancreatic carcinogenesis. In this study, we show that lipopolysaccharide accelerates pancreatic tumorigenesis, whereas TLR4 inhibition is protective. Furthermore, blockade of the MyD88-independent TRIF pathway is protective against pancreatic cancer, whereas blockade of the MyD88-dependent pathway surprisingly exacerbates pancreatic inflammation and malignant progression. The protumorigenic and fibroinflammatory effects of MyD88 inhibition are mediated by dendritic cells (DCs), which induce pancreatic antigen-restricted Th2-deviated CD4(+) T cells and promote the transition from pancreatitis to carcinoma. Our data implicate a primary role for DCs in pancreatic carcinogenesis and illustrate divergent pathways in which blockade of TLR4 signaling via TRIF is protective against pancreatic cancer and, conversely, MyD88 inhibition exacerbates pancreatic inflammation and neoplastic transformation by augmenting the DC-Th2 axis.
Journal of Experimental Medicine 08/2012; 209(9):1671-87. · 13.85 Impact Factor
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Junaid Ibrahim,
Andrew H Nguyen, Adeel Rehman,
Atsuo Ochi,
Mohsin Jamal,
Christopher S Graffeo,
Justin R Henning,
Constantinos P Zambirinis,
Nina C Fallon,
Rocky Barilla,
Sana Badar,
Aaron Mitchell,
Raghavendra S Rao,
Devrim Acehan,
Alan B Frey,
George Miller
[show abstract]
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ABSTRACT: Immune cells of the liver must be able to recognize and react to pathogens yet remain tolerant to food molecules and other nonpathogens. Dendritic cells (DCs) are believed to contribute to hepatic tolerance. Lipids have been implicated in dysfunction of DCs in cancer. Therefore, we investigated whether high lipid content in liver DCs affects induction of tolerance.
Mouse and human hepatic nonparenchymal cells were isolated by mechanical and enzymatic digestion. DCs were purified by fluorescence-activated cell sorting or with immunomagnetic beads. DC lipid content was assessed by flow cytometry, immune fluorescence, and electron microscopy and by measuring intracellular component lipids. DC activation was determined from surface phenotype and cytokine profile. DC function was assessed in T-cell, natural killer (NK) cell, and NKT cell coculture assays as well as in vivo.
We observed 2 distinct populations of hepatic DCs in mice and humans based on their lipid content and expression of markers associated with adipogenesis and lipid metabolism. This lipid-based dichotomy in DCs was unique to the liver and specific to DCs compared with other hepatic immune cells. However, rather than mediate tolerance, the liver DC population with high concentrations of lipid was immunogenic in multiple models; they activated T cells, NK cells, and NKT cells. Conversely, liver DCs with low levels of lipid induced regulatory T cells, anergy to cancer, and oral tolerance. The immunogenicity of lipid-rich liver DCs required their secretion of tumor necrosis factor α and was directly related to their high lipid content; blocking DC synthesis of fatty acids or inhibiting adipogenesis (by reducing endoplasmic reticular stress) reduced DC immunogenicity.
Human and mouse hepatic DCs are composed of distinct populations that contain different concentrations of lipid, which regulates immunogenic versus tolerogenic responses in the liver.
Gastroenterology 06/2012; 143(4):1061-72. · 11.68 Impact Factor
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Andrea S Bedrosian,
Andrew H Nguyen,
Michael Hackman,
Michael K Connolly,
Ashim Malhotra,
Junaid Ibrahim,
Napoleon E Cieza-Rubio,
Justin R Henning,
Rocky Barilla, Adeel Rehman,
H Leon Pachter,
Marco V Medina-Zea,
Steven M Cohen,
Alan B Frey,
Devrim Acehan,
George Miller
[show abstract]
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ABSTRACT: The cellular mediators of acute pancreatitis 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.
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 method.
Numbers of major histocompatibility complex II(+)CD11c(+) DCs increased 100-fold in pancreata of mice with acute pancreatitis to account for nearly 15% of intrapancreatic leukocytes. Intrapancreatic DCs acquired a distinct immune phenotype in mice with acute pancreatitis; they expressed higher levels of major histocompatibility complex II and CD86 and increased production of interleukin-6, membrane cofactor protein-1, and tumor necrosis factor-α. However, rather than inducing an organ-destructive inflammatory process, DCs were required for pancreatic viability; the exocrine pancreas died in mice that were depleted of DCs and challenged with caerulein or L-arginine. All mice with pancreatitis that were depleted of DCs died from acinar cell death within 4 days. Depletion of DCs from mice with pancreatitis resulted in neutrophil infiltration and increased levels of systemic markers of inflammation. However, the organ necrosis associated with depletion of DCs did not require infiltrating neutrophils, activation of nuclear factor-κB, or signaling by mitogen-activated protein kinase or tumor necrosis factor-α.
DCs are required for pancreatic viability in mice with acute pancreatitis and might protect organs against cell stress.
Gastroenterology 07/2011; 141(5):1915-26.e1-14. · 11.68 Impact Factor
