26 results found
Khamri W, Gudd C, Liu T, et al., 2021, Suppressor CD4+ T cells expressing HLA-G are expanded in the peripheral blood from patients with acute decompensation of cirrhosis, Gut, Vol: 71, Pages: 1192-1202, ISSN: 0017-5749
Objective Identifying components of immuneparesis, a hallmark of chronic liver failure, is crucial for our understanding of complications in cirrhosis. Various suppressor CD4+ T cells have been established as potent inhibitors of systemic immune activation. Here, we establish the presence, regulation and mechanism of action of a suppressive CD4+ T cell subset expressing human leucocyte antigen G (HLA-G) in patients with acute decompensation of cirrhosis (AD).Design Flow cytometry was used to determine the proportion and immunophenotype of CD4+HLA-G+ T cells from peripheral blood of 20 healthy controls (HCs) and 98 patients with cirrhosis (28 with stable cirrhosis (SC), 20 with chronic decompensated cirrhosis (CD) and 50 with AD). Transcriptional and functional signatures of cell-sorted CD4+HLA-G+ cells were delineated by NanoString technology and suppression assays, respectively. The role of immunosuppressive cytokine interleukin (IL)-35 in inducing this population was investigated through in vitro blockade experiments. Immunohistochemistry (IHC) and cultures of primary human Kupffer cells (KCs) were performed to assess cellular sources of IL-35. HLA-G-mediated T cell suppression was explored using neutralising antibodies targeting co-inhibitory pathways.Results Patients with AD were distinguished by an expansion of a CD4+HLA-G+CTLA-4+IL-35+ immunosuppressive population associated with disease severity, clinical course of AD, infectious complications and poor outcome. Transcriptomic analyses excluded the possibility that these were thymic-derived regulatory T cells. IHC analyses and in vitro cultures demonstrate that KCs represent a potent source of IL-35 which can induce the observed HLA-G+ phenotype. These exert cytotoxic T lymphocyte antigen-4-mediated impaired responses in T cells paralleled by an HLA-G-driven downregulation of T helper 17-related cytokines.Conclusion We have identified a cytokine-driven peripherally derived suppressive population that may contr
Possamai L, Gudd C, Au L, et al., 2021, Activation and transcriptional profile of monocytes and CD8+ T cells are altered in checkpoint inhibitor-related hepatitis, Journal of Hepatology, Vol: 75, Pages: 177-189, ISSN: 0168-8278
Background & Aims: Checkpoint inhibitor-related hepatitis (CPI-Hep) is an emerging clinical challenge. We aimed to gain insights into the immunopathology of CPI-Hep by comprehensively characterising myeloid and lymphoid subsets.Methods: CPI-treated patients with or without related hepatitis (CPI-Hep; n = 22 and CPI-noHep; n = 7) were recruited. Phenotypic and transcriptional profiling of peripheral immune subsets was performed and compared with 19 healthy controls (HCs). In vitro monocyte-derived macrophages (MoMFs) were assessed for activation and cytokine production. CD163, CCR2, CD68, CD3, CD8 and granzyme B expression was assessed using immunohistochemistry/immunofluorescence (n = 4).Results: A significant total monocyte depletion was observed in CPI-Hep compared with HCs (p = 0.04), along with a proportionate increase in the classical monocyte population (p = 0.0002) and significant upregulation of CCR2, CD163 and downregulation of CCR7. Soluble CD163 levels were significantly elevated in CPI-Hep compared with HCs (p <0.0001). In vitro MoMFs from CPI-Hep showed enhanced production of pro-inflammatory cytokines. CD8+ T cells demonstrated increased perforin, granzyme B, ICOS and HLA-DR expression in CPI-Hep. Transcriptional profiling indicated the presence of activated monocyte and enhanced effector CD8+ T cell populations in CPI-Hep. Immunohistochemistry demonstrated co-localisation of CD8+/granzyme B+ T cells with CD68+CCR2+/CD68+CD163+ macrophages in CPI-Hep liver tissue.Conclusions: CPI-Hep is associated with activation of peripheral monocytes and an enhanced cytotoxic, effector CD8+ T cell phenotype. These changes were reflected by liver inflammation composed of CD163+/CCR2+ macrophages and CD8+ T cells.Lay summary: Some patients who receive immunotherapy for cancer develop liver inflammation, which requires cessation of cancer treatment. Herein, we describe ways in which the white blood cells of patients who develop liver inflammation differ from tho
Triantafyllou E, Gudd C, Mawhin M-A, et al., 2020, PD-1 blockade improves Kupffer cell bacterial clearance in acute liver injury, Journal of Clinical Investigation, Vol: 131, Pages: 1-16, ISSN: 0021-9738
Acute liver failure (ALF) patients display systemic innate immune suppression and increased susceptibility to infections. PD-1 expression by macrophages has been associated with immune suppression during sepsis and cancer. We therefore examined the role of PD-1/PD-L1 pathway in regulating Kupffer cell inflammatory and antimicrobial responses in acetaminophen (APAP) induced acute liver injury. Using intravital imaging and flow cytometry we found impaired Kupffer cell bacterial clearance and systemic bacterial dissemination in mice with liver injury. Increased PD-1 and PD-L1 expression was detected in Kupffer cells and lymphocyte subsets, respectively, during resolution of injury. Gene expression profiling of PD-1+ Kupffer cells revealed an immune-suppressive profile and reduced pathogen responses. Compared to wild-type, PD-1 deficient or anti-PD-1 treated mice with liver injury showed improved Kupffer cell bacterial clearance, reduced tissue bacterial load and protection from sepsis. Blood sample analyses of ALF patients revealed enhanced PD-1 and PD-L1 expression of monocytes and lymphocytes, respectively, and that plasma soluble PD-L1 levels predict patient outcome and sepsis. PD-1 in vitro blockade restored monocyte functionality. Our study describes a role for PD-1/PD-L1 axis in suppressing Kupffer cell and monocyte antimicrobial responses after liver injury and suggests anti-PD-1 immunotherapy as a strategy to reduce infection susceptibility in ALF.
Lebosse F, Gudd C, Tunc E, et al., 2019, CD8+ T cells from patients with cirrhosis display a phenotype that may contribute to cirrhosis-associated immune dysfunction, EBioMedicine, Vol: 49, Pages: 258-268, ISSN: 2352-3964
BackgroundCirrhosis-associated immune dysfunction (CAID) contributes to high sepsis risk in patients with chronic liver disease. Various innate and; to a lesser extent; adaptive immune dysfunctions have been described as contributors to CAID leading to immune-paresis and impaired anti-microbial response in cirrhosis. In this study, we examined the phenotype of CD8+ T cells in chronic liver disease with the aim to evaluate changes that might contribute to impaired immune responses.MethodsSixty patients with cirrhosis were prospectively recruited for this study. CD8+ T cells from peripheral blood, ascites and liver explants were characterized using flow cytometry and immunohistochemistry, respectively. The transcriptional signature of flow-sorted HLA-DR+CD8+ T cells was performed using Nanostring™ technology. HLA-DR+CD8+ T cells interactions with PBMCs and myeloid cells were tested in vitro.FindingsPeripheral CD8+ T cells from cirrhotic patients displayed an altered phenotype characterized by high HLA-DR and TIM-3 surface expression associated with concomitant infections and disease severity, respectively. Paired peritoneal CD8+ T cells expressed more pronounced levels of HLA-DR and PD-1 compared to peripheral CD8+ T cells. HLA-DR+CD8+ T cells were enriched in cirrhotic livers compared to controls. TIM-3, CTLA-4 and PD-1 levels were highly expressed on HLA-DR+CD8+ T cells and co-expression of HLA-DR and PD1 was higher in patients with poor disease outcomes. Genes involved in cytokines production and intracellular signalling pathways were strongly down-regulated in HLA-DR+CD8+ T cells. In comparison to their HLA-DR− counterparts, HLA-DR+CD8+ T cells promoted less proliferation of PBMCs and induced phenotypic and functional dysfunctions in monocytes and neutrophils in vitro.InterpretationIn patients with cirrhosis, CD8+ T cells display a phenotypic, functional and transcriptional profile which may contribute to CAID.FundThis work was supported by Medical Res
Bernsmeier C, Triantafyllou E, Brenig R, et al., 2018, CD14+CD15-HLA-DR- myeloid-derived suppressor cells impair antimicrobial responses in patients with acute-on-chronic liver failure, Gut, Vol: 67, Pages: 1155-1167, ISSN: 1468-3288
Objective Immune paresis in patients with acute-on-chronic liver failure (ACLF) accounts for infection susceptibility and increased mortality. Immunosuppressive mononuclear CD14+HLA-DR− myeloid-derived suppressor cells (M-MDSCs) have recently been identified to quell antimicrobial responses in immune-mediated diseases. We sought to delineate the function and derivation of M-MDSC in patients with ACLF, and explore potential targets to augment antimicrobial responses.Design Patients with ACLF (n=41) were compared with healthy subjects (n=25) and patients with cirrhosis (n=22) or acute liver failure (n=30). CD14+CD15−CD11b+HLA-DR− cells were identified as per definition of M-MDSC and detailed immunophenotypic analyses were performed. Suppression of T cell activation was assessed by mixed lymphocyte reaction. Assessment of innate immune function included cytokine expression in response to Toll-like receptor (TLR-2, TLR-4 and TLR-9) stimulation and phagocytosis assays using flow cytometry and live cell imaging-based techniques.Results Circulating CD14+CD15−CD11b+HLA-DR− M-MDSCs were markedly expanded in patients with ACLF (55% of CD14+ cells). M-MDSC displayed immunosuppressive properties, significantly decreasing T cell proliferation (p=0.01), producing less tumour necrosis factor-alpha/interleukin-6 in response to TLR stimulation (all p<0.01), and reduced bacterial uptake of Escherichia coli (p<0.001). Persistently low expression of HLA-DR during disease evolution was linked to secondary infection and 28-day mortality. Recurrent TLR-2 and TLR-4 stimulation expanded M-MDSC in vitro. By contrast, TLR-3 agonism reconstituted HLA-DR expression and innate immune function ex vivo.Conclusion Immunosuppressive CD14+HLA-DR− M-MDSCs are expanded in patients with ACLF. They were depicted by suppressing T cell function, attenuated antimicrobial innate immune responses, linked to secondary infection, disease severity and prognosis. TLR-3 ag
Triantafyllou E, Pop O, Possamai L, et al., 2017, MerTK expressing hepatic macrophages promote the resolution of inflammation in acute liver failure, Gut, Vol: 67, Pages: 333-347, ISSN: 1468-3288
Objective Acute liver failure (ALF) is characterised by overwhelming hepatocyte death and liver inflammation with massive infiltration of myeloid cells in necrotic areas. The mechanisms underlying resolution of acute hepatic inflammation are largely unknown. Here, we aimed to investigate the impact of Mer tyrosine kinase (MerTK) during ALF and also examine how the microenvironmental mediator, secretory leucocyte protease inhibitor (SLPI), governs this response.Design Flow cytometry, immunohistochemistry, confocal imaging and gene expression analyses determined the phenotype, functional/transcriptomic profile and tissue topography of MerTK+ monocytes/macrophages in ALF, healthy and disease controls. The temporal evolution of macrophage MerTK expression and its impact on resolution was examined in APAP-induced acute liver injury using wild-type (WT) and Mer-deficient (Mer−/−) mice. SLPI effects on hepatic myeloid cells were determined in vitro and in vivo using APAP-treated WT mice.Results We demonstrate a significant expansion of resolution-like MerTK+HLA-DRhigh cells in circulatory and tissue compartments of patients with ALF. Compared with WT mice which show an increase of MerTK+MHCIIhigh macrophages during the resolution phase in ALF, APAP-treated Mer−/− mice exhibit persistent liver injury and inflammation, characterised by a decreased proportion of resident Kupffer cells and increased number of neutrophils. Both in vitro and in APAP-treated mice, SLPI reprogrammes myeloid cells towards resolution responses through induction of a MerTK+HLA-DRhigh phenotype which promotes neutrophil apoptosis and their subsequent clearance.Conclusions We identify a hepatoprotective, MerTK+, macrophage phenotype that evolves during the resolution phase following ALF and represents a novel immunotherapeutic target to promote resolution responses following acute liver injury.
Khamri W, Abeles RD, Hou TZ, et al., 2017, Increased expression of CTLA4 by T cells, induced by B7 in sera, reduces adaptive immunity in patients with acute liver failure, Gastroenterology, Vol: 153, Pages: 263-276.e8, ISSN: 0016-5085
BACKGROUND & AIMS: Patients with acute liver failure (ALF) have defects in innate immune responses to microbes (immuneparesis) and are susceptible to sepsis. Cytotoxic T-lymphocyte associated protein 4 (CTLA4), which interacts with the membrane receptor B7 (also called CD80 and CD86), is a negative regulator of T-cell activation. We collected T cells from patients with ALF and investigated whether inhibitory signals downregulate adaptive immune responses in patients with ALF. METHODS: We collected peripheral blood mononuclear cells from patients with ALF and controls from September 2013 through September 2015 (45 patients with ALF, 20 patients with acute-on-chronic liver failure, 15 patients with cirrhosis with no evidence of acute decompensation, 20 patients with septic shock but no cirrhosis or liver disease, and 20 healthy individuals). Circulating CD4+T cells were isolated and analyzed by flow cytometry. CD4+ T cells were incubated with antigen, or agonist to CD3 and dendritic cells, with or without antibody against CTLA4; T-cell proliferation and protein expression were quantified. We measured levels of soluble B7 molecules in supernatants of isolated primary hepatocytes, hepatic sinusoidal endothelial cells, and biliary epithelial cells from healthy or diseased liver tissues. We also measured levels of soluble B7 serum samples from patients and controls, and mice with acetaminophen-induced liver injury using ELISAs. RESULTS: Peripheral blood samples from patients with ALF had a higher proportion of CD4+ CTLA4+ T cells than controls; patients with infections had the highest proportions. CD4+T cells from patients with ALF had a reduced proliferative response to antigen or CD3 stimulation compared to cells from controls; incubation of CD4+T cells from patients with ALF w
Vergis N, Khamri W, Beale K, et al., 2016, Defective monocyte oxidative burst predicts infection in alcoholic hepatitis and is associated with reduced expression of NADPH oxidase, Gut, Vol: 66, Pages: 519-529, ISSN: 1468-3288
Objective In order to explain the increasedsusceptibility to serious infection in alcoholic hepatitis,we evaluated monocyte phagocytosis, aberrations ofassociated signalling pathways and their reversibility, andwhether phagocytic defects could predict subsequentinfection.Design Monocytes were identified from blood samplesof 42 patients with severe alcoholic hepatitis usingmonoclonal antibody to CD14. Phagocytosis andmonocyte oxidative burst (MOB) were measured ex vivousing flow cytometry, luminometry and bacterial killingassays. Defects were related to the subsequentdevelopment of infection. Intracellular signallingpathways were investigated using western blotting andPCR. Interferon-γ (IFN-γ) was evaluated for itstherapeutic potential in reversing phagocytic defects.Paired longitudinal samples were used to evaluate theeffect of in vivo prednisolone therapy.Results MOB, production of superoxide and bacterialkilling in response to Escherichia coli were markedlyimpaired in patients with alcoholic hepatitis.Pretreatment MOB predicted development of infectionwithin two weeks with sensitivity and specificity thatwere superior to available clinical markers. Accordingly,defective MOB was associated with death at 28 and90 days. Expression of the gp91phox subunit ofnicotinamide adenine dinucleotide phosphate (NADPH)oxidase was reduced in patients with alcoholic hepatitisdemonstrating defective MOB. Monocytes were refractoryto IFN-γ stimulation and showed high levels of anegative regulator of cytokine signalling, suppressor ofcytokine signalling-1. MOB was unaffected by 7 days invivo prednisolone therapy.Conclusions Monocyte oxidative burst and bacterialkilling is impaired in alcoholic hepatitis while bacterialuptake by phagocytosis is preserved. Defective MOB isassociated with reduced expression of NADPH oxidase inthese patients and predicts the development of infectionand death.
Bernsmeier C, Pop OT, Singanayagam A, et al., 2015, Patients with acute-on-chronic liver failure have increased numbers of regulatory immune cells expressing the receptor tyrosine kinase MERTK, Gastroenterology, Vol: 148, Pages: 603-615.e14, ISSN: 0016-5085
Background & AimsCharacteristics of decompensated cirrhosis and acute-on-chronic liver failure (ACLF) include susceptibility to infection, immuneparesis, and monocyte dysfunction. MER receptor tyrosine kinase (MERTK) is expressed by monocytes and macrophages and contributes to down-regulation of innate immune responses. We investigated whether MERTK expression is altered on monocytes from patients with liver failure.MethodsWe analyzed blood and liver samples collected from patients admitted to the liver intensive therapy unit at King’s College Hospital in London from December 2012 through July 2014. Patients had either ACLF (n = 41), acute decompensation of cirrhosis without ACLF (n = 9), cirrhosis without decompensation (n = 17), or acute liver failure (n = 23). We also analyzed samples from healthy individuals (controls, n = 29). We used flow cytometry to determine the level of innate immune function, and associated the findings with disease severity. We developed an assay to measure recruitment and migration of immune cells from the tissue parenchyma. Immunohistochemistry and confocal microscopy were used to determine levels of MERTK in bone marrow, liver, and lymph node tissues. We performed immunophenotype analyses and measured the production of tumor necrosis factor and interleukin 6 and intracellular killing of Escherichia coli by monocytes and peritoneal macrophages incubated with lipopolysaccharide, with or without an inhibitor of MERTK (UNC569).ResultsThe number of monocytes and macrophages that expressed MERTK was greatly increased in the circulation, livers, and lymph nodes of patients with ACLF, compared with patients with stable cirrhosis and controls. MERTK expression (mean fluorescence intensity) correlated with the severity of hepatic and extrahepatic disease and systemic inflammatory responses. Based on immunophenotype, migration, and functional analyses, MERTK-expressing monocytes migrate across the endothelia to localize into tissue sit
Possamai LA, McPhail MJW, Khamri W, et al., 2014, The role of intestinal microbiota in murine models of acetaminophen-induced hepatotoxicity, Liver International, Vol: 35, Pages: 764-773, ISSN: 1478-3231
Background & AimsVariations in intestinal microbiota may influence acetaminophen metabolism. This study aimed to determine whether intestinal microbiota are a source of differential susceptibility to acetaminophen-induced hepatotoxicity.MethodsConventionally housed C3H/HeH (CH) and C3H/HeH germ-free (GF) mice were administered a 200 mg/kg IP dose of acetaminophen. The severity of hepatotoxicity at 8 h was assessed by histology and biochemical indices. A urinary metabolic profile was obtained using 1H-NMR. Baseline hepatic glutathione content and CYP2E1 expression were quantified. An additional group of C3H/HeJ (LPS-r) mice were assessed to determine the contribution of LPS/TLR4 signalling.ResultsBaseline glutathione levels were significantly reduced (P = 0.03) in GF mice. CYP2E1 mRNA expression and protein levels were not altered. Interindividual variability did not differ between GF and CH groups. No significant differences in the extent of hepatocellular injury (ALT or percentage necrosis) were demonstrated. However, a milder acute liver failure (ALF) phenotype was shown in GF compared with CH mice, with reduced plasma bilirubin and creatinine and increased blood glucose. Differential acetaminophen metabolism was demonstrated. GF mice displayed a higher urinary acetaminophen-sulphate:glucuronide ratio compared with CH (P = 0.01). Urinary analysis showed metabolic differentiation of GF and CH groups at baseline and 8 h (cross-validated anova P = 1 × 10-22). Interruption of TLR4 signalling in LPS-r mice had additional protective effects.ConclusionVariations in intestinal microbiota do not fully explain differential susceptibility to acetaminophen-induced hepatotoxicity. GF mice experienced some protection from secondary complications following acetaminophen overdose and this may be mediated through reduced TLR4/LPS signalling.
Possamai LA, Khamri W, Triantafyllou E, et al., 2014, Could targeting secretory leukocyte protease inhibitor be an effective therapeutic option to prevent infections in acute liver failure?, IMMUNOTHERAPY, Vol: 6, Pages: 667-669, ISSN: 1750-743X
Vergis N, Khamri W, Atkinson S, et al., 2014, Monocyte oxidative burst defect predicts risk of infection in alcoholic hepatitis, International Liver Conference 2014/ 49th Annual Meeting of the European Association for the Study of the Liver, Publisher: Elsevier Science BV, Pages: S168-S168, ISSN: 0168-8278
Antoniades C, 2013, Secretory Leukocyte Protease Inhibitor: a pivotal mediator of anti-inflammatory responses in acetaminophen induced acute liver failure, Hepatology
Afzali B, Mitchell PJ, Edozie FC, et al., 2013, CD161 expression characterizes a subpopulation of human regulatory T cells that produces IL-17 in a STAT3-dependent manner., Eur J Immunol, Vol: 43, Pages: 2043-2054
Treg cells are critical for the prevention of autoimmune diseases and are thus prime candidates for cell-based clinical therapy. However, human Treg cells are "plastic", and are able to produce IL-17 under inflammatory conditions. Here, we identify and characterize the human Treg subpopulation that can be induced to produce IL-17 and identify its mechanisms. We confirm that a subpopulation of human Treg cells produces IL-17 in vitro when activated in the presence of IL-1β, but not IL-6. "IL-17 potential" is restricted to population III (CD4(+) CD25(hi) CD127(lo) CD45RA(-) ) Treg cells expressing the natural killer cell marker CD161. We show that these cells are functionally as suppressive and have similar phenotypic/molecular characteristics to other subpopulations of Treg cells and retain their suppressive function following IL-17 induction. Importantly, we find that IL-17 production is STAT3 dependent, with Treg cells from patients with STAT3 mutations unable to make IL-17. Finally, we show that CD161(+) population III Treg cells accumulate in inflamed joints of patients with inflammatory arthritis and are the predominant IL-17-producing Treg-cell population at these sites. As IL-17 production from this Treg-cell subpopulation is not accompanied by a loss of regulatory function, in the context of cell therapy, exclusion of these cells from the cell product may not be necessary.
Abeles RD, McPhail MJ, Sowter D, et al., 2012, CD14, CD16 and HLA-DR reliably identifies human monocytes and their subsets in the context of pathologically reduced HLA-DR expression by CD14(hi)/CD16(neg) monocytes: Expansion of CD14(hi)/CD16(pos) and contraction of CD14(lo)/CD16(pos) monocytes in acute liver failure, CYTOMETRY PART A, Vol: 81A, Pages: 823-834, ISSN: 1552-4922
Li K, Fazekasova H, Wang N, et al., 2011, Expression of complement components, receptors and regulators by human dendritic cells., Mol Immunol, Vol: 48, Pages: 1121-1127
Integration of innate and adaptive arms of the immune response at a cellular and molecular level appears to be fundamental to the development of powerful effector functions in host defence and aberrant immune responses. Here we provide evidence that the functions of human complement activation and antigen presentation converge on dendritic cells (DCs). We show that several subsets of human DCs [i.e., monocyte derived (CD1a(+)CD14(-)), dermal (CD1a(+)DC-SIGN(+)), Langerhans (CD1a(+)Langerin(+)), myeloid (CD1c(+)CD19(-)), plamacytoid (CD45RA(+)CD123(+))] express many of the components of the classical and alternative and terminal pathways of complement. Moreover human DCs have receptors known to detect the biologically active peptides C3a and C5a (C3aR, C5aR) and the covalently bound fragments C3b and metabolites iC3b and C3d which serve in immune adhesion (i.e., CR3, CR4, CRIg). We also show that the human DC surface is characterised by membrane bound regulators of complement activation, which are also known to participate in intracellular signalling (i.e., CD46, CD55, CD59). This work provides an extensive description of complement components relevant to the integrated actions of complement and DC, illuminated by animal studies. It acts as a resource that allows further understanding and exploitation of role of complement in human health and immune mediated diseases.
Thursz MR, Khamri W, 2010, Host Surfactant Proteins in Microbial Recognition, Microbial Glycobiology, Pages: 697-713, ISBN: 9780123745460
The cellular responses of host defenses against microbial invasion require pathogen-associated molecular pattern (PAMPs) recognition molecules. Surfactant proteins (SP) SP-A and SP-D, members of the collectin family, recognize PAMPs and act as important mediators of the immune system. Both SP-A and SP-D interact with various microorganism- and pathogen-derived components by binding to complex carbohydrate structures of bacterial, viral, and fungal cells. The binding occurs via the surfactant carbohydrate recognition domain and leads to the agglutination and enhancement of pathogen clearance by specialized immune cells. In addition to their interaction with bacterial cells, SP-A and SP-D have a direct effect on immune cell function. This chapter discusses the structure, biosynthesis, ligands, and functions of SP-A and SP-D. Furthermore, the possible clinical applications for both SP-A and SP-D are highlighted. © 2010 Elsevier Inc. All rights reserved.
Khamri W, Walker MM, Clark P, et al., 2010, Helicobacter pylori stimulates dendritic cells to induce interleukin-17 expression from CD4+ T lymphocytes., Infect Immun, Vol: 78, Pages: 845-853
Helicobacter pylori is a human gastroduodenal pathogen that leads to active chronic inflammation characterized by T-cell responses biased toward a Th1 phenotype. It has been accepted that H. pylori infection induces a Th17 response. At mucosal sites, dendritic cells (DCs) have the capacity to induce effector T cells. Here, we evaluate the role of DCs in the H. pylori-induced interleukin-17 (IL-17) response. Immunohistochemistry and immunofluorescence were performed on human gastric mucosal biopsy samples and showed that myeloid DCs in H. pylori-infected patients colocalized with IL-23- and that IL-17-producing lymphocytes were present in H. pylori-infected antral biopsy samples. In parallel, human monocyte-derived DCs stimulated in vitro with live H. pylori cells produced significant levels of IL-23 in the absence of IL-12 release. The subsequent incubation of H. pylori-infected DCs with autologous CD4(+) T cells led to gamma interferon (IFN-gamma) and IL-17 expression. The inhibition of IL-1 and, to a lesser extent, IL-23 inhibited IL-17 production by T cells. Finally, isogenic H. pylori mutant strains not expressing major virulence factors were less effective in inducing IL-1 and IL-23 release by DCs and IL-17 release by T cells than parental strains. Altogether, we can conclude that DCs are potent inducers of IL-23/IL-17 expression following H. pylori stimulation. IL-1/IL-23 as well as H. pylori virulence factors seem to play an important role in mediating this response.
Thursz MR, Khamri W, 2009, Host surfactant proteins in microbial recognition, Microbial Glycobiology: Structures, Relevance and Applications, Pages: 697-713, ISBN: 9780123745460
The cellular responses of host defenses against microbial invasion require pathogen-associated molecular pattern (PAMPs) recognition molecules. Surfactant proteins (SP) SP-A and SP-D, members of the collectin family, recognize PAMPs and act as important mediators of the immune system. Both SP-A and SP-D interact with various microorganism- and pathogen-derived components by binding to complex carbohydrate structures of bacterial, viral, and fungal cells. The binding occurs via the surfactant carbohydrate recognition domain and leads to the agglutination and enhancement of pathogen clearance by specialized immune cells. In addition to their interaction with bacterial cells, SP-A and SP-D have a direct effect on immune cell function. This chapter discusses the structure, biosynthesis, ligands, and functions of SP-A and SP-D. Furthermore, the possible clinical applications for both SP-A and SP-D are highlighted.
Anderson AE, Worku ML, Khamri W, et al., 2007, TLR9 polymorphisms determine murine lymphocyte responses to Helicobacter: Results from a genome-wide scan, EUROPEAN JOURNAL OF IMMUNOLOGY, Vol: 37, Pages: 1548-1561, ISSN: 0014-2980
Khamri W, Worku ML, Anderson AE, et al., 2007, Helicobacter infection in the surfactant protein D-deficient mouse, HELICOBACTER, Vol: 12, Pages: 112-123, ISSN: 1083-4389
Mitchell P, Germain C, Fiori PL, et al., 2007, Chronic exposure to Helicobacter pylori impairs dendritic cell function and inhibits Th1 development, INFECTION AND IMMUNITY, Vol: 75, Pages: 810-819, ISSN: 0019-9567
Moran AP, Khamri W, Walker MM, et al., 2005, Role of surfactant protein D (SP-D) in innate immunity in the gastric mucosa: evidence of interaction with Helicobacter pylori lipopolysaccharide, JOURNAL OF ENDOTOXIN RESEARCH, Vol: 11, Pages: 357-362, ISSN: 0968-0519
Khamri W, Moran AP, Worku ML, et al., 2005, Variations in Helicobacter pylori lipopolysaccharide to evade the innate immune component surfactant protein D, INFECTION AND IMMUNITY, Vol: 73, Pages: 7677-7686, ISSN: 0019-9567
Cooke VM, Miles RJ, Price RG, et al., 2002, New chromogenic agar medium for the identification of Candida spp., Appl Environ Microbiol, Vol: 68, Pages: 3622-3627, ISSN: 0099-2240
A new chromogenic agar medium (Candida diagnostic agar [CDA]) for differentiation of Candida spp. is described. This medium is based on Sabouraud dextrose agar (Oxoid CM41) and contains (per liter) 40.0 g of glucose, 10.0 g of mycological peptone, and 15.0 g of agar along with a novel chromogenic glucosaminidase substrate, ammonium 4-(2-[4-(2-acetamido-2-deoxy-beta-D-glucopyranosyloxy)-3-methoxyphenyl]-vinyl)-1-(propan-3-yl-oate)-quinolium bromide (0.32 g liter(-1)). The glucosaminidase substrate in CDA was hydrolyzed by Candida albicans and Candida dubliniensis, yielding white colonies with deep-red spots on a yellow transparent background after 24 to 48 h of incubation at 37 degrees C. Colonies of Candida tropicalis and Candida kefyr were uniformly pink, and colonies of other Candida spp., including Candida glabrata and Candida parapsilosis, were white. CDA was evaluated by using 115 test strains of Candida spp. and other clinically important yeasts and was compared with two commercially available chromogenic agars (Candida ID agar [bioMerieux] and CHROMagar Candida [CHROMagar Company Ltd.]). On all three agars, colonies of C. albicans were not distinguished from colonies of C. dubliniensis. However, for the group containing C. albicans plus C. dubliniensis, both the sensitivity and the specificity of detection when CDA was used were 100%, compared with values of 97.6 and 100%, respectively, with CHROMagar Candida and 100 and 96.8%, respectively, with Candida ID agar. In addition, for the group containing C. tropicalis plus C. kefyr, the sensitivity and specificity of detection when CDA was used were also 100%, compared with 72.7 and 98.1%, respectively, with CHROMagar Candida. Candida ID agar did not differentiate C. tropicalis and C. kefyr strains but did differentiate members of a broader group (C. tropicalis, C. kefyr, Candida lusitaniae plus Candida guilliermondii); the sensitivity and specificity of detection for members of this group were 94.7 and 93.8%, re
Murray E, Khamri W, Walker MM, et al., 2002, Expression of surfactant protein D in the human gastric mucosa and during Helicobacter pylori infection, INFECTION AND IMMUNITY, Vol: 70, Pages: 1481-1487, ISSN: 0019-9567
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