G S Ogg

NIHR Oxford Biomedical Research, Oxford, England, United Kingdom

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Publications (127)787.78 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Histamine is an abundant mediator accumulating in the skin of atopic patients where it is thought to be immune cell-derived. While keratinocytes express histidine decarboxylase (HDC), levels of the enzyme in normal or diseased epidermis and factors that influence its expression in human keratinocytes are not known.
    British Journal of Dermatology 06/2014; · 3.76 Impact Factor
  • Clinical Immunology 04/2014; · 3.77 Impact Factor
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    ABSTRACT: The role of the epidermis in the immune response is well known. While multiple cytokines are implicated in keratinocyte-mediated infection clearance and wound healing, little is known about the involvement of keratinocytes in promoting resolution of inflammation. To assess effects of histamine stimulation on keratinocyte function. We performed a combined microarray/Gene Ontology analysis of histamine-stimulated keratinocytes. Functional changes were tested by apoptosis assessment and scratch assays. Histamine receptor involvement was also assessed by blocking wound closure with specific antagonists. Histamine treatment had extensive effects on keratinocytes, including effects on proinflammatory responses and cellular functions promoting wound healing. At the functional level, there was reduced apoptosis and enhancement of wound healing in vitro. At the receptor level, we identified involvement of all keratinocyte-expressed histamine receptors (HRHs), with HRH1 blockage resulting in the most prominent effect. Histamine activates wound healing and infection clearance-related functions of keratinocytes. While enhancement of histamine-mediated wound healing is mediated predominantly via the HRH1 receptor, other keratinocyte-expressed receptors are also involved. These effects could promote resolution of skin inflammation caused by infection or superficial injury.
    Clinical and Experimental Dermatology 01/2014; · 1.33 Impact Factor
  • Clinical Immunology. 01/2014;
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    ABSTRACT: Activation of the group 2 innate lymphoid cell (ILC2) population leads to production of the classical type 2 cytokines, thus promoting type 2 immunity. Chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2), a receptor for prostaglandin D2 (PGD2), is expressed by human ILC2s. However, the function of CRTH2 in these cells is unclear. We sought to determine the role of PGD2 and CRTH2 in human ILC2s and compare it with that of the established ILC2 activators IL-25 and IL-33. The effects of PGD2, IL-25, and IL-33 on the cell migration, cytokine production, gene regulation, and receptor expression of ILC2s were measured with chemotaxis, ELISA, Luminex, flow cytometry, quantitative RT-PCR, and QuantiGene assays. The effects of PGD2 under physiologic conditions were evaluated by using the supernatant from activated mast cells. PGD2 binding to CRTH2 induced ILC2 migration and production of type 2 cytokines and many other cytokines. ILC2 activation through CRTH2 also upregulated the expression of IL-33 and IL-25 receptor subunits (ST2 and IL-17RA). The effects of PGD2 on ILC2s could be mimicked by the supernatant from activated human mast cells and inhibited by a CRTH2 antagonist. PGD2 is an important and potent activator of ILC2s through CRTH2 mediating strong proallergic inflammatory responses. Through IgE-mediated mast cell degranulation, these innate cells can also contribute to adaptive type 2 immunity; thus CRTH2 bridges the innate and adaptive pathways in human ILC2s.
    The Journal of allergy and clinical immunology 12/2013; · 12.05 Impact Factor
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    ABSTRACT: Type 2 innate lymphoid cells (ILC2s, nuocytes, NHC) require RORA and GATA3 for their development. We show that human ILC2s express skin homing receptors and infiltrate the skin after allergen challenge, where they produce the type 2 cytokines IL-5 and IL-13. Skin-derived ILC2s express the IL-33 receptor ST2, which is up-regulated during activation, and are enriched in lesional skin biopsies from atopic patients. Signaling via IL-33 induces type 2 cytokine and amphiregulin expression, and increases ILC2 migration. Furthermore, we demonstrate that E-cadherin ligation on human ILC2 dramatically inhibits IL-5 and IL-13 production. Interestingly, down-regulation of E-cadherin is characteristic of filaggrin insufficiency, a cardinal feature of atopic dermatitis (AD). ILC2 may contribute to increases in type 2 cytokine production in the absence of the suppressive E-cadherin ligation through this novel mechanism of barrier sensing. Using Rag1(-/-) and RORα-deficient mice, we confirm that ILC2s are present in mouse skin and promote AD-like inflammation. IL-25 and IL-33 are the predominant ILC2-inducing cytokines in this model. The presence of ILC2s in skin, and their production of type 2 cytokines in response to IL-33, identifies a role for ILC2s in the pathogenesis of cutaneous atopic disease.
    Journal of Experimental Medicine 12/2013; · 13.21 Impact Factor
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    ABSTRACT: Comprehensive antigenic characterization of a T cell population of unknown specificity is challenging. Existing MHC class I expression systems are limited by the practical difficulty of probing cell populations with an MHC class I peptide library and the cross-reactivity of T cells that are able to recognise many variants of an index peptide. Using emulsion PCR and emulsion in vitro transcription/translation of a random library of peptides conjugated to CD8-null HLA-A*0201 on beads, we probed HLA-A*0201-restricted T cells with specificity for influenza, CMV and EBV. We observed significant enrichment for sequences containing HLA-A2 anchors and correct viral fragments for all T cell populations. HLA bead display provides a novel approach to identify the specificity of T cells.
    Journal of immunological methods 12/2013; · 2.35 Impact Factor
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    ABSTRACT: Genotyping of wild type of varicella zoster virus (VZV) in Sri Lanka would help to distinguish the VZV wild type infection from varicella vaccine associated infections. PCR-RFLP analysis of VZV ORF 38, 54 and 62 was used for genotyping in VZV from blood or vesicular fluid from 31 patients with chickenpox or herpes zoster. The PstI restriction site of ORF 38, BglI restriction site of ORF 54 and SmaI restriction site of ORF 62 were analyzed using RFLP to determine the genotype. Except for one strain, all other VZV isolates had the genotype characteristic of the wild type VZV strain PstI+BglI+ SmaI-, which was characteristic of the Asian strain. None of the isolates had the American or the European VZV profile (PstI+BglI-) but were similar to isolates from Africa and Asia (PstI+BglI+). Interestingly, one of the VZV strains isolated from a patient with chickenpox had the characteristic genotype of the vaccine strain PstI- BglI+ SmaI+. The genotype of the VZV in Sri Lanka is similar to the Asian VZV genotype and can be easily distinguished from the VZV vaccine strain by using the polymorphisms in ORF 38, ORF 54 and ORF 62.
    Ceylon Medical Journal 12/2013; 58(4):153-6.
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    ABSTRACT: Dengue viral infections are the commonest mosquito borne viral infection in the world, affecting more than 100 countries and 390 million individuals annually. Currently, there are no effective antiviral drugs or an effective vaccine to prevent infection. A main hurdle in developing a safe and effective vaccine has been our poor understanding of the complex nature of the protective immune response in acute dengue infection and the presence of four dengue virus (DV) serotypes that are highly homologous. The role of DV specific T cells in the pathogenesis of severe clinical disease in not clear. It has been speculated that highly cross reactive T cells for the previous infecting heterologous DV serotype, which produce pro-inflammatory cytokines, contribute to disease pathogenesis. These cross reactive T cells are believed to be suboptimal in clearing the infection with the current DV-serotype. However, other studies have shown that cross-reactive DV-specific T cells are absent or present in very low frequency during acute infection, appearing only during the convalescent period in the majority of patients. Furthermore, significant apoptosis of T cells occurs in severe acute clinical disease. Overall therefore, it is unclear what role T cells play in contributing to disease pathogenesis during acute dengue infection. Existing data have been complicated by cross-reactivity in T cells assays. These findings can now be re-evaluated in the light of novel technologies to identify serotype-specific T cell responses.
    Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology 10/2013; · 3.12 Impact Factor
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    ABSTRACT: Several studies have shown that serum IL-10, IFNgamma and MIF are elevated in patients in severe dengue (SD) and could be used as potential biomarkers. We proceeded to determine if these cytokines could be used as biomarkers in a large cohort of adult dengue patients with varying severity of dengue infection. Serum IL-10 levels were determined in 259 of whom 40 had severe dengue infection. Serum IFNgamma andIFNalpha levels were done in 78 and MIF levels were done in 65 patients with acute dengue infection. Clinical features and laboratory investigations were undertaken during the febrile and critical phase. We found that serum IL-10 levels were significantly higher (p = 0.001) in patients with SD, when compared to those with non SD. Serum IL-10 levels significantly and inversely correlated with white cell counts (R = -0.23, p = 0.0002) and lymphocyte counts (R = -0.29, p < 0.0001) but significantly and positively correlated with aspartate tranaminase levels (R = 0.16, p = 0.01) and alanine transaminase levels (R = 0.22, p = 0.007). However, IL-10 levels did not have a good predictive value in discriminating those who were likely to develop SD (AUC = 0.66). Serum IFNgamma levels were also significantly higher (p = 0.04) in patients with SD when compared to non SD. There was no difference (p = 0.34) in serum IFNalpha levels and serum MIF levels (p = 0.15) in patients with SD and non SD. Although serum IL-10 was significantly elevated in patients with SD it had a poor discriminatory value in identifying those with SD and non SD and therefore, is unsuitable to be used as a robust biomarker in this cohort.
    BMC Infectious Diseases 07/2013; 13(1):341. · 3.03 Impact Factor
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    ABSTRACT: Studies published in recent years have highlighted the role of epidermal barrier defects in both atopic skin disease and the development of broader allergic manifestations. While genetic determinants of barrier function are important, it is clear that local acquired effects are also involved in disease pathogenesis. In this review, we aimed to summarize the known influences of cytokines abundantly expressed during atopic skin disease on components of epidermal barrier integrity and function.
    Clinical & Experimental Allergy 06/2013; 43(6):586-598. · 4.79 Impact Factor
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    ABSTRACT: We investigated the relationship between varicella zoster virus (VZV)-specific memory CD4(+) T cells and CD4(+)Foxp3(+) regulatory T cells (Tregs) that accumulate after intradermal challenge with a VZV skin test Ag. VZV-specific CD4(+) T cells were identified with a MHC class II tetramer or by intracellular staining for either IFN-γ or IL-2 after Ag rechallenge in vitro. VZV-specific T cells, mainly of a central memory (CD45RA(-)CD27(+)) phenotype, accumulate at the site of skin challenge compared with the blood of the same individuals. This resulted in part from local proliferation because >50% of tetramer defined Ag-specific CD4(+) T cells in the skin expressed the cell cycle marker Ki67. CD4(+)Foxp3(+) T cells had the characteristic phenotype of Tregs, namely CD25(hi)CD127(lo)CD39(hi) in both unchallenged and VZV challenged skin and did not secrete IFN-γ or IL-2 after antigenic restimulation. The CD4(+)Foxp3(+) T cells from unchallenged skin had suppressive activity, because their removal led to an increase in cytokine secretion after activation. After VZV Ag injection, Foxp3(+)CD25(hi)CD127(lo)CD39(hi) T cells were also found within the VZV tetramer population. Their suppressive activity could not be directly assessed by CD25 depletion because activated T cells in the skin were also CD25(+). Nevertheless, there was an inverse correlation between decreased VZV skin responses and proportion of CD4(+)Foxp3(+) T cells present, indicating indirectly their inhibitory activity in vivo. These results suggest a linkage between the expansion of Ag-specific CD4(+) T cells and CD4(+) Tregs that may provide controlled responsiveness during Ag-specific stimulation in tissues.
    The Journal of Immunology 01/2013; · 5.52 Impact Factor
  • New England Journal of Medicine 01/2013; 368(18):1695-1703. · 51.66 Impact Factor
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    ABSTRACT: Although peptides are well recognised biological molecules in vivo, their selection from libraries is challenging because of relative low affinity whilst in linear conformation. We hypothesized that multiplexed peptides and DNA on the surface of beads would provide a platform for enhanced avidity and the selection of relevant peptides from a library (ORBIT bead display). Using human immunodeficiency virus (HIV-1) gp120 as a target, we identify peptides that inhibit HIV-1 replication in vitro through blocking of protein:protein interaction with the co-receptor CCR5. The bead display approach has many potential applications for probing biological systems and for drug lead development.
    Scientific Reports 01/2013; 3:3030. · 2.93 Impact Factor
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    ABSTRACT: Elevated IL-10 has been shown to be associated with severe dengue infection (DI). We proceeded to investigate the role of IL-10 in the pathogenesis of acute DI. Ex vivo and cultured IFNγ ELISpot assays for dengue virus (DENV) NS3 protein and non dengue viral proteins were carried out in 26 patients with acute DI (16 with dengue haemorrhagic fever) and 12 healthy dengue seropositive individuals from Sri Lanka. DENV serotype specific (SS) responses were determined by using a panel of SS peptides. Serum IL-10 level were significantly higher (p = 0.02) in those who did not have in vitro responses to DENV-SS peptides (mean 144.2 pg/ml) when compared to those who responded (mean 75.7 pg/ml). DENV-NS3 specific ex vivo IFNγ ELISpot responses were also significantly lower (p = 0.0001) in those who did not respond to DENV-SS peptides (mean 42 SFU/million PBMCs) when compared to those who responded to DENV-SS peptides (mean 1024 SFU/million PBMCs). Serum IL-10 levels correlated significantly (p = 0.03) and inversely (Spearmans R = -0.45) with ex vivo DENV-NS3 specific responses but not with ex vivo non DENV specific responses (Spearmans R = -014, p = 0.52). Blockage of IL-10 in vitro significantly increased (p = 0.04) the ex vivo IFNγ ELISpot DENV-NS3 specific responses but had no effect on responses to non DENV proteins. IL-10 appears to contribute to the pathogenesis of acute dengue infections by inhibiting DENV-specific T cell responses, which can be restored by blocking IL-10.
    PLoS Neglected Tropical Diseases 01/2013; 7(9):e2409. · 4.57 Impact Factor
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    ABSTRACT: BACKGROUND: The WHO guidelines were revised recently to identify patients with severe dengue (SD) early. We proceeded to determine the usefulness of the warning signs in the new WHO guidelines in predicting SD and we have also attempted to define other simple laboratory parameters that could be useful in predicting SD. METHODS: Clinical and laboratory parameters were recorded in 184 patients in 2011, with confirmed dengue viral infections, admitted to a medical ward in two tertiary care hospitals in Colombo, Sri Lanka. RESULTS: We found that the presence of 5 or more dengue warning signs were significantly (p = 0.02) associated with the development of SD (odds ratio 5.14, 95% CI = 1.312 to 20.16). The AST levels were significantly higher (p = 0.0001) in patients with abdominal pain (mean 243.5, SD +/- 200.7), when compared to those who did not have abdominal pain (mean 148.5, SD +/- 218.6). Lymphocyte counts <1,500 cells/mm3 were significantly (p = 0.005) associated with SD (odds ratio 3.367, 95% CI 1.396 to 8.123). High AST levels were also significantly associated (p < 0.0001) with SD (odds ratio 27.26, 95% CI 1.632 to 455.2). Platelet counts <20,000cells/mm3, were again significantly associated (p < 0.001) with severe disease (odds ratio 1.632 to 455.2, 95% CI 3.089 to 14.71). The PCR was positive in 26/84 of the patients and we found that the infecting serotype was DEN-1 in all 26 patients. CONCLUSIONS: The presence of 5 or more warning signs appears to be a predictor of SD. Lymphocyte counts <1,500 cells/mm3, platelet counts <20,000/mm3 and raised AST levels were associated with SD and could be used to help identify patients who are likely to develop SD.
    BMC Research Notes 11/2012; 5(1):645.
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    G N Malavige, G Ogg
    Ceylon Medical Journal 09/2012; 57(3):97-100.
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    ABSTRACT: There is mounting evidence that antimicrobial peptides have an important role in cutaneous defence, but the expression of these antimicrobial peptides in atopic eczema (AE) is still unclear. There are several families of antimicrobial peptides, including cathelicidins and human β-defensins. Patients with AE are more susceptible to severe cutaneous viral infections, including varicella zoster virus (VZV). To characterize the functional activity of the antimicrobial peptides LL-37 (human cathelicidin) and human β-defensin (hBD)-2 keratinocytes were infected with VZV, in a skin-infection model. Flow-cytometry analysis was used to investigate LL-37 expression in normal human keratinocytes, and quantitative PCR was used to determine viral loads in infected HaCaT keratinocytes and B cells, with and without exogenous LL-37 and hBD-2. LL-37 expression was present in keratinocytes, and both exogenous LL-37 and hBD-2 significantly reduced VZV load in infected keratinocytes and B cells. Specific antibodies blocked the antiviral action exhibited by these antimicrobial peptides. Pre-incubation of VZV with LL-37, but not hBD-2, further reduced VZV load. Both LL-37 and hBD-2 have an antiviral effect on VZV replication in the keratinocyte HaCaT cell line and in B cells, but their mechanism of action is different. Evidence of the relationship between antimicrobial peptide expression and higher susceptibility to infections in AE skin is still emerging. Developing novel antiviral therapies based on antimicrobial peptides may provide improved treatment options for patients with AE.
    Clinical and Experimental Dermatology 05/2012; 37(5):534-43. · 1.33 Impact Factor
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    ABSTRACT: Determining previous infecting dengue virus (DENV) serotypes has been difficult due to highly cross-reactive immune responses from previous DENV infections. Determining the correlates of serotype-specific immune responses would be crucial in understanding dengue transmission in the community and would also help to determine the correlates of protective immune responses. Therefore, we set out to define highly conserved, serotype-specific regions of the DENVs. Serotype-specific and highly conserved regions of the four DENV serotypes were identified using Basic Local Alignment Search Tool (BLAST) searches and custom perl scripts. Using ex-vivo and cultured enzyme-linked immunospot (ELISPOT) assays, we identified serotype-specific T cell epitopes within the four DENV serotypes in healthy adult donors from Sri Lanka. We identified T cell responses to 19 regions of the four DENV serotypes. Six peptides were from the NS2A region and four peptides were from the NS4A region. All immune donors responded to peptides of at least two DENV serotypes, suggesting that heterologous infection is common in Sri Lanka. Eight of 20 individuals responded to at least two peptides of DENV-4, despite this serotype not being implicated previously in any of the epidemics in Sri Lanka. The use of these regions to determine past and current infecting DENV serotypes will be of value to characterize further the dynamics of silent dengue transmission in the community. In addition, these T cell responses to these regions could be used to characterize DENV serotype-specific immune responses and thus possibly help us to understand the immune correlates of a protective immune response.
    Clinical & Experimental Immunology 05/2012; 168(2):215-23. · 3.41 Impact Factor
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    ABSTRACT: BACKGROUND: Pyoderma gangrenosum (PG) is a rare inflammatory skin disorder characterised by painful and rapidly progressing skin ulceration. PG can be extremely difficult to treat and patients often require systemic immunosuppression. Recurrent lesions of PG are common, but the relative rarity of this condition means that there is a lack of published evidence regarding its treatment. A systematic review published in 2005 found no randomised controlled trials (RCTs) relating to the treatment of PG. Since this time, one small RCT has been published comparing infliximab to placebo, but none of the commonly used systemic treatments for PG have been formally assessed. The UK Dermatology Clinical Trials Network's STOP GAP Trial has been designed to address this lack of trial evidence. METHODS: The objective is to assess whether oral ciclosporin is more effective than oral prednisolone for the treatment of PG. The trial design is a two-arm, observer-blind, parallel-group, randomised controlled trial comparing ciclosporin (4 mg/kg/day) to prednisolone (0.75 mg/kg/day). A total of 140 participants are to be recruited over a period of 4 years, from up to 50 hospitals in the UK and Eire. Primary outcome of velocity of healing at 6 weeks is assessed blinded to treatment allocation (using digital images of the ulcers). Secondary outcomes include: (i) time to healing; (ii) global assessment of improvement; (iii) PG inflammation assessment scale score; (iv) self-reported pain; (v) health-related quality of life; (vi) time to recurrence; (vii) treatment failures; (viii) adverse reactions to study medications; and (ix) cost effectiveness/utility. Patients with a clinical diagnosis of PG (excluding granulomatous PG); measurable ulceration (that is, not pustular PG); and patients aged over 18 years old who are able to give informed consent are included in the trial. Randomisation is by computer generated code using permuted blocks of randomly varying size, stratified by lesion size, and presence or absence of underlying systemic disease (for example, rheumatoid arthritis).Patients who require topical therapy are asked to enter a parallel observational study (case series). If topical therapy fails and systemic therapy is required, participants are then considered for inclusion in the randomised trial. TRIAL REGISTRATION: Current controlled trials: ISRCTN35898459. Eudract No.2008-008291-14.
    Trials 04/2012; 13:51. · 2.21 Impact Factor

Publication Stats

10k Citations
787.78 Total Impact Points

Institutions

  • 2008–2014
    • NIHR Oxford Biomedical Research
      Oxford, England, United Kingdom
  • 1997–2013
    • University of Oxford
      • • MRC Human Immunology Unit
      • • Nuffield Department of Clinical Medicine
      • • Weatherall Institute of Molecular Medicine
      Oxford, England, United Kingdom
  • 2012
    • University of Sri Jayewardenepura
      Columbo, Western, Sri Lanka
  • 2009
    • Institute of Genetics and Molecular Medicine
      Edinburgh, Scotland, United Kingdom
  • 1996–2008
    • Oxford University Hospitals NHS Trust
      • Nuffield Department of Medicine
      Oxford, England, United Kingdom
  • 2000–2005
    • The Institute for Molecular Medicine
      Huntington Beach, California, United States
    • Harvard University
      • Center for AIDS Research
      Cambridge, MA, United States
  • 1999–2004
    • Imperial College London
      • Faculty of Medicine
      London, ENG, United Kingdom
  • 2002
    • Mrc Harwell
      Oxford, England, United Kingdom
    • Nottinghamshire Healthcare NHS Trust
      Nottigham, England, United Kingdom
  • 2001
    • The Rockefeller University
      New York City, New York, United States
    • J. David Gladstone Institutes
      San Francisco, California, United States
  • 1999–2000
    • Massachusetts General Hospital
      • Division of Infectious Diseases
      Boston, Massachusetts, United States
    • University College London
      Londinium, England, United Kingdom
  • 1998
    • Ludwig Institute for Cancer Research
      La Jolla, California, United States