Medicine and Health Sciences Commons^™

Differences In Innate Immune Signaling Between Alcoholic And Non-Alcoholic Steatohepatitis, Jan Petrasek, Timea Csak, Michal Ganz, Gyongyi Szabo

Gyongyi Szabo

The similar histopathological characteristics of alcoholic steatohepatitis (ASH) and non-alcoholic steatohepatitis (NASH), and the crucial role of the innate immune response in both conditions may lead to the assumption that ASH and NASH represent the same pathophysiological entities caused by different risk factors. In this review paper, we elaborate on the pathophysiological differences between these two entities and highlight the disease-specific involvement of signaling molecules downstream of the Toll-like receptor 4, and the differential mechanism by which the inflammasome contributes to ASH versus NASH. Our findings emphasize that ASH and NASH have disease-specific mechanisms and therefore represent distinct biological entities. …

An Essential Role For Monocyte Chemoattractant Protein-1 In Alcoholic Liver Injury: Regulation Of Proinflammatory Cytokines And Hepatic Steatosis In Mice, Pranoti Mandrekar, Aditya Ambade, Arlene Lim, Gyongyi Szabo, Donna Catalano

Gyongyi Szabo

The importance of chemokines in alcoholic liver injury has been implicated. The role of the chemokine, monocyte chemoattractant protein-1 (MCP-1), elevated in patients with alcoholic liver disease is not yet understood. Here, we evaluated the pathophysiological significance of MCP-1 and its receptor, chemokine (C-C motif) receptor 2 (CCR2), in alcoholic liver injury. The Leiber-DeCarli diet containing alcohol or isocaloric control diets were fed to wild-type (WT) and MCP-1-deficient knockout (KO) mice for 6 weeks. In vivo and in vitro assays were performed to study the role of MCP-1 in alcoholic liver injury. MCP-1 was increased in Kupffer cells (KCs) as …

Critical Role Of Toll-Like Receptors And The Common Tlr Adaptor, Myd88, In Induction Of Granulomas And Liver Injury, Arumugam Velayudham, Istvan Hritz, Angela Dolganiuc, Pranoti Mandrekar, Evelyn Kurt-Jones, Gyongyi Szabo

Gyongyi Szabo

BACKGROUND/AIMS: Toll-like receptors (TLR) recognize pathogens and regulate innate immune activation. Here, we investigated the roles of TLR9 and the common TLR adaptor, MyD88, in liver injury.

METHODS: C57BL6, TLR9(-/-), IFNgamma(-/-) or MyD88(-/-) mice were primed with Propionibacterium acnes, TLR9 (CpG) or TLR2 (lipoteichoic acid) ligands followed by LPS challenge. ALT, cytokines and liver histology were assessed.

RESULTS: Selective priming through TLR9 but not TLR2 induced granulomas, elevated serum ALT, and sensitized C57BL6 mice to increased LPS-induced serum IL-6, IL-12 and IFNgamma levels. Further, TLR2 and TLR9 ligands synergized in induction of granulomas and sensitization to LPS-induced inflammation. IFNgamma induction …

Cytokines And Alcohol, Fulton Crews, Rabih Bechara, Lou Ann Brown, David Guidot, Pranoti Mandrekar, Shilpa Oak, Liya Qin, Gyongyi Szabo, Michael Wheeler, Jian Zou

Gyongyi Szabo

Cytokines are multifunctional proteins that play a critical role in cellular communication and activation. Cytokines have been classified as being proinflammatory (T helper 1, Th1) or anti-inflammatory (T helper 2, Th2) depending on their effects on the immune system. However, cytokines impact a variety of tissues in a complex manner that regulates inflammation, cell death, and cell proliferation and migration as well as healing mechanisms. Ethanol (alcohol) is known to alter cytokine levels in a variety of tissues including plasma, lung, liver, and brain. Studies on human monocyte responses to pathogens reveal ethanol disruption of cytokine production depending upon the …

The Opposite Effects Of Acute And Chronic Alcohol On Lipopolysaccharide-Induced Inflammation Are Linked To Irak-M In Human Monocytes, Pranoti Mandrekar, Shashi Bala, Donna Catalano, Karen Kodys, Gyongyi Szabo

Gyongyi Szabo

Impaired host defense after alcohol use is linked to altered cytokine production, however, acute and chronic alcohol differently modulate monocyte/macrophage activation. We hypothesized that in human monocytes, acute alcohol induces hyporesponsiveness to LPS, resulting in decreased TNF-alpha, whereas chronic alcohol increases TNF-alpha by sensitization to LPS. We found that acute alcohol increased IL-1R-associated kinase-monocyte (IRAK-M), a negative regulator of IRAK-1, in human monocytes. This was associated with decreased IkappaB alpha kinase activity, NFkappaB DNA binding, and NFkappaB-driven reporter activity after LPS stimulation. In contrast, chronic alcohol decreased IRAK-M expression but increased IRAK-1 and IKK kinase activities, NFkappaB DNA binding, and …

Bone Marrow-Derived Immune Cells Mediate Sensitization To Liver Injury In A Myeloid Differentiation Factor 88-Dependent Fashion, Istvan Hritz, Arumugam Velayudham, Angela Dolganiuc, Karen Kodys, Pranoti Mandrekar, Evelyn Kurt-Jones, Gyongyi Szabo

Gyongyi Szabo

Toll-like receptors (TLRs) expressed on both immune cells and hepatocytes recognize microbial danger signals and regulate immune responses. Previous studies showed that TLR9 and TLR2 mediate Propionibacterium acnes-induced sensitization to lipopolysaccharide-triggered acute liver injury in mice. Ligand-specific activation of TLR2 and TLR9 are dependent on the common TLR adaptor, myeloid differentiation factor 88 (MyD88). Here, we dissected the role of MyD88 in parenchymal and bone marrow (BM)-derived cells in liver sensitization. Using chimeric mice with green fluorescent protein-expressing BM cells, we identified that P. acnes-induced liver inflammatory foci are of BM origin. Chimeras with MyD88-deficient BM showed no inflammatory foci …

Signalling Pathways In Alcohol-Induced Liver Inflammation, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

The pathogenesis of alcoholic liver injury involves interactions of several intracellular signalling pathways in different cell types of the liver. Alcohol-induced sensitization of liver macrophages to portal endotoxin/lipopolysaccharide (LPS) is considered a hallmark of alcoholic liver disease (ALD). Intracellular mechanisms associated with LPS-induced signalling play a crucial role in the initiation and progression of alcoholic liver injury, and are being extensively explored. LPS recognition by Toll-like receptor 4 (TLR4) on macrophages and other cell types in the liver, activation of downstream signalling pathways culminating in activation of transcription factors such as NFkappaB, AP-1 leads to increased inflammatory cytokine production in …

Increased Lipopolysaccharide Sensitivity In Alcoholic Fatty Livers Is Independent Of Leptin Deficiency And Toll-Like Receptor 4 (Tlr4) Or Tlr2 Mrna Expression, Laszlo Romics, Pranoti Mandrekar, Karen Kodys, Arumugam Velayudham, Yvonne Drechsler, Angela Dolganiuc, Gyongyi Szabo

Gyongyi Szabo

BACKGROUND: Both alcoholic (AFL) and nonalcoholic (NAFL) fatty livers show increased sensitivity to endotoxin-induced injury. Lipopolysaccharide (LPS) is recognized by toll-like receptor 4 (TLR4), whereas lipopeptide triggers TLR2 to induce common downstream activation of nuclear factor (NF)-kappaB and pro-inflammatory pathways that are activated in AFL and NAFL. METHODS: Serum alanine aminotransferase (ALT), tumor necrosis factor (TNF)-alpha, and interleukin (IL)-6 levels; hepatic NF-kappaB activity; and expression of TLR2, TLR4, inducible nitric oxide synthase (iNOS), and heme oxygenase (HO)-1 mRNAs were investigated in lean and leptin-deficient ob/ob mice after LPS challenge in combination with acute or chronic alcohol feeding. RESULTS: Increased LPS …

Liver In Sepsis And Systemic Inflammatory Response Syndrome, Gyongyi Szabo, Laszlo Romics, Gyorgy Frendl

Gyongyi Szabo

In patients with sepsis and SIRS, the liver has two opposing roles: a source of inflammatory mediators and a target organ for the effects of the inflammatory mediators. The liver is pivotal in modulating the systemic response to severe infection, because it contains the largest mass of macrophages (Kupffer cells) in the body; these macrophages can clear the endotoxin and bacteria that initiate the systemic inflammatory response. This article summarizes the functional changes that take place in the liver during sepsis and systemic inflammatory response syndrome and discusses the cellular and molecular mechanisms that underlie clinical outcomes.

Selective Priming To Toll-Like Receptor 4 (Tlr4), Not Tlr2, Ligands By P. Acnes Involves Up-Regulation Of Md-2 In Mice, Laszlo Romics, Angela Dolganiuc, Karen Kodys, Yvonne Drechsler, Shilpa Oak, Arumugam Velayudham, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

Lipopolysaccharide (LPS) triggers cytokine production through Toll-like receptor 4 (TLR4), which shares downstream signaling pathways with TLR2. We investigated the roles of TLR2 and TLR4 in Propionibacterium acnes (P. acnes)-primed, LPS-induced liver damage using selective TLR ligands. Stock LPS induced interleukin 8 in both TLR4- and TLR2-expressing human embryonic kidney (HEK) 293 cells. Purified LPS (TLR4 ligand) activated HEK/TLR4 cells, while peptidoglycan and lipoteichoic acid (TLR2 ligands) activated HEK/TLR2 cells, respectively. In mice, P. acnes priming resulted in increased liver messenger RNA (mRNA) and serum levels of tumor necrosis factor alpha, interleukin 12, and interferon gamma (IFN-gamma) by both stock …

Regulation Of Human Monocyte Functions By Acute Ethanol Treatment: Decreased Tumor Necrosis Factor-Alpha, Interleukin-1 Beta And Elevated Interleukin-10, And Transforming Growth Factor-Beta Production, Gyongyi Szabo, Pranoti Mandrekar, Linda Girouard, Donna Catalano

Gyongyi Szabo

We and others have previously shown that even acute ethanol exposure has the capacity to modulate immune functions, particularly monocyte functions. Herein, we tested the hypothesis that acute ethanol treatment inhibits inflammatory, while increasing inhibitory cytokine production in human blood monocytes that, in turn, could contribute to the overall immune abnormalities seen after alcohol use. Our data show that in vitro treatment of blood monocytes with a physiologically relevant dose of alcohol (25 mM) results in significantly decreased induction of tumor necrosis factor-alpha (TNF alpha) and interleukin (IL)-1 beta by bacterial stimulation of either Gram-positive [staphylococcal enterotoxin B (SEB), 1 …

Monocytes, Alcohol Use, And Altered Immunity, Gyongyi Szabo

Gyongyi Szabo

The immunomodulatory capacity of acute, moderate alcohol consumption was investigated in this study in nonalcoholic volunteers after 2 ml of vodka/kg body weight of alcohol consumption. There was a significant, transient increase in interleukin-12 and interferon-gamma (IFNgamma) levels in whole blood samples collected 4 hr after alcohol consumption in response to an ex vivo bacterial challenge with lipopolysaccharide (p < 0.02). However, decreased IFNgamma levels were produced by mononuclear cells collected later after alcohol consumption (16 hr), suggesting that acute alcohol consumption has a biphasic effect on IFNgamma inducibility. Furthermore, isolated blood monocytes collected 16 hr after alcohol consumption showed significantly …

Diverse Regulation Of Nf-Kappab And Peroxisome Proliferator-Activated Receptors In Murine Nonalcoholic Fatty Liver, Laszlo Romics, Karen Kodys, Angela Dolganiuc, Lucia Graham, Arumugam Velayudham, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

Fatty liver is highly sensitive to inflammatory activation. Peroxisome proliferator-activated receptors (PPAR) have anti-inflammatory effects and regulate lipid metabolism in the fatty liver. We hypothesized that fatty liver leads to endotoxin sensitivity through an imbalance between pro- and anti-inflammatory signals. Leptin-deficient, ob/ob mice and their lean littermates were challenged with single or double insults and pro- and anti-inflammatory pathways were tested on cytokine production and activation of nuclear regulatory factors NF-kappaB and peroxisome proliferator receptor element (PPRE). Ob/ob mice produced significantly higher serum tumor necrosis factor alpha (TNF-alpha) and interleukin (IL) 6 and showed increased hepatic NF-kappaB activation compared to …

Regulation Of Monocyte Interleukin-12 Production By Acute Alcohol: A Role For Inhibition By Interleukin-10, Linda Girouard, Pranoti Mandrekar, Donna Catalano, Gyongyi Szabo

Gyongyi Szabo

Acute ethanol treatment results in decreased antigen presentation capacity (Th1-type immunity) and elevated interleukin IL-10 (Th2 cytokine) production in human monocytes. Monocytes can contribute to both Th1 (IL-12) and Th2 (IL-10) immune responses via production of IL-12 and IL-10, respectively. Thus, we tested the hypothesis that acute alcohol treatment might affect Th1/Th2 immune balance by altering monocyte production of IL-12 and IL-10. Neither acute ethanol treatment alone (25 to 100 mM) nor its combination with a bacterial challenge Staphylococcal enterotoxin B (SEB) induced IL-12 production in isolated blood monocytes. In contrast, the same physiological alcohol concentrations increased monocyte IL-10 levels, …

Viral And Host Factors Induce Macrophage Activation And Loss Of Toll-Like Receptor Tolerance In Chronic Hcv Infection, Angela Dolganiuc, Oxana Norkina, Karen Kodys, Donna Catalano, Gennadiy Bakis, Christopher Marshall, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

BACKGROUND and AIMS: Persistent inflammation contributes to progression of liver damage in chronic HCV (cHCV) infection. Repeated exposure to toll-like receptor (TLR) ligands results in tolerance, a protective mechanism aimed at limiting inflammation.

METHODS: Monocytes/macrophages were repeatedly stimulated via proinflammatory cytokine-inducing TLRs and evaluated for activation markers.

RESULTS: Unlike monocytes of controls or patients with nonalcoholic steatohepatitis, the monocytes of cHCV patients were hyperresponsive and failed to show homo- or heterotolerance to TLR ligands, manifested by elevated tumor necrosis factor (TNF)-alpha production. Serum levels of interferon (IFN)-gamma, endotoxin (TLR4 ligand), and HCV core protein (TLR2 ligand) were elevated in cHCV …

Ethanol-Mediated Regulation Of Transcription Factors In Immunocompetent Cells, Gyongyi Szabo, Pranoti Mandrekar

Gyongyi Szabo

The immunomodulatory effects of acute and chronic alcohol use are characterized by impaired antigen-specific immune activation and by increased susceptibility to infections due to alterations in innate immune responses and inflammatory mediator production. The central feature of cellular responses to inflammatory and stress signals is the activation of the nuclear regulatory kappa B/Rel family of transcriptional factors via various surface receptor systems in immunocompetent cells. Activation of NF-kappa B, however, is regulated at multiple levels including I-kappa B degradation, nuclear translocation, and by interaction of NF-kappa B/Rel with other transcription factors. Data from our and other laboratories demonstrate that acute …

Modulation Of Non-Alcoholic Steatohepatitis By Pattern Recognition Receptors In Mice: The Role Of Toll-Like Receptors 2 And 4, Gyongyi Szabo, Arumugam Velayudham, Laszlo Romics, Pranoti Mandrekar

Gyongyi Szabo

Toll-like receptors (TLR) recognize pathogen-derived molecules and induce downstream activation of inflammatory pathways. Fatty liver has been shown to result in increased sensitivity to lipopolysaccharide (LPS), a TLR4 ligand. In this study, we investigated the roles of TLR2 and TLR4 in liver damage and on cytokine induction in a methionine-choline deficient (MCD) diet-induced model of nonalcoholic steatohepatitis. We found that mice with nonalcoholic fatty liver had increased liver injury and inflammatory cytokine induction after challenge with a TLR4 but not with a TLR2 ligand. TLR2 deficient mice were not protected against the development of steatohepatitis after MCD diet feeding. On …

Moderate Alcohol Intake In Humans Attenuates Monocyte Inflammatory Responses: Inhibition Of Nuclear Regulatory Factor Kappa B And Induction Of Interleukin 10, Pranoti Mandrekar, Donna Catalano, Bernadette White, Gyongyi Szabo

Gyongyi Szabo

BACKGROUND: In contrast to the deleterious effects of chronic excessive alcohol consumption on the liver and cardiovascular system, modest alcohol intake, such as 1 to 2 drinks per day, has benefits on cardiovascular mortality. Little is known about the length of time or the amounts of alcohol consumed that may cause alterations in inflammatory cells such as monocytes that are crucial to atherosclerotic vascular disease. Here, we determine in vivo effects of acute alcohol consumption on inflammatory cytokine production and nuclear regulatory factor kappaB (NF-kappaB) binding in human monocytes. METHODS: Human blood monocytes were isolated by plastic adherence before and …

Acute Ethanol Treatment Modulates Toll-Like Receptor-4 Association With Lipid Rafts, Angela Dolganiuc, Genadyi Bakis, Karen Kodys, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

BACKGROUND: Alcohol, a substance that is most frequently abused, suppresses innate immune responses to microbial pathogens. The host senses pathogens via Toll-like receptors (TLRs). Recent studies indicate that alcohol affects TLR signaling. METHODS: Here, we hypothesized that acute alcohol treatment may interfere with early steps of membrane-associated TLR2 and TLR4 signaling at the level of lipid rafts. Human monocytes and Chinese hamster ovary (CHO) cells, transfected with human TLR2, TLR4, or CD14, were stimulated with peptidoglycan (PGN, TLR2 ligand) or lipopolysaccharide (LPS, TLR4 ligand) with or without alcohol (50 mM) and analyzed for cytokine production (enzyme-linked immunosorbent assay), nuclear factor-kappaB …

Induction Of Transforming Growth Factor-Beta And Prostaglandin E2 Production By Ethanol In Human Monocytes, Gyongyi Szabo, Bikash Verma, Miklos Fogarasi, Donna Catalano

Gyongyi Szabo

To test our hypothesis that monocytes (M phi) and their mediators are major contributors to ethanol-related immunodepression, the modulating capacity of acute ethanol treatment was assessed on the production of transforming growth factor-beta (TGF beta) and prostaglandin E2 (PGE2) by human peripheral blood M phi. We demonstrate that acute in vitro treatment of adherent M phi with either 50 or 150 mM ethanol induced a significant increase in the production of TGF beta (P < 0.045 and P < 0.001, respectively). Furthermore, M phi pretreatment with both 50 and 150 mM ethanol augmented TGF beta production in response to subsequent stimulation with …

Acute Alcohol Exposure Exerts Anti-Inflammatory Effects By Inhibiting Ikappab Kinase Activity And P65 Phosphorylation In Human Monocytes, Pranoti Mandrekar, Valentina Jeliazkova, Donna Catalano, Gyongyi Szabo

Gyongyi Szabo

Acute alcohol use is associated with impaired immune responses and decreased proinflammatory cytokine production. Our earlier studies have shown that acute alcohol intake inhibits NF-kappaB DNA binding in an IkappaBalpha-independent manner. We report using human peripheral blood monocytes and Chinese hamster ovary cells transfected with CD14 cells that acute alcohol treatment in vitro exerts NF-kappaB inhibition by disrupting phosphorylation of p65. Immunoprecipitation of p65 and IkappaBalpha revealed that acute alcohol exposure for 1 h decreased NF-kappaB-IkappaBalpha complexes in the cytoplasm. Phosphorylation of p65 at Ser(536) is mediated by IkappaB kinase (IKK)beta and is required for NF-kappaB-dependent cellular responses. We show …

Toll-Like Receptor 2 Mediates Inflammatory Cytokine Induction But Not Sensitization For Liver Injury By Propioni- Bacterium Acnes, Laszlo Romics, Angela Dolganiuc, Arumugam Velayudham, Karen Kodys, Pranoti Mandrekar, Douglas Golenbock, Evelyn Kurt-Jones, Gyongyi Szabo

Gyongyi Szabo

Recognition of Gram-positive bacteria by Toll-like receptor 2 (TLR2) induces activation of proinflammatory pathways. In mice, sensitization with the Gram-positive Propionibacterium acnes followed by a challenge with the TLR4 ligand, lipopolysaccharide (LPS), results in fulminant hepatic failure. Here, we investigated the role of TLR2 in liver sensitization to LPS-induced injury. Stimulation of Chinese hamster ovary cells and peritoneal macrophages with heat-killed P. acnes required expression of TLR2 but not of TLR4, suggesting that P. acnes was a TLR2 ligand. Cell activation by P. acnes was myeloid differentiation primary-response protein 88 (MyD88)-dependent, and it was augmented by coexpression of CD14 in …