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Sedger L.M.,University of Technology, Sydney | Sedger L.M.,Institute for Immunology and Allergy Research | Katewa A.,University of Technology, Sydney | Katewa A.,Institute for Immunology and Allergy Research | And 7 more authors.

To delineate the relative roles of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas ligand in lymphocyte biology and lymphoproliferative disease, we generated mice defective in both molecules. B6.GT mice develop severe polyclonal lymphoproliferative disease because of accumulating CD3+CD4- CD8-B220+ T cells, CD4+ and CD8+ T cells, and follicular B cells, and mice die prematurely from extreme lymphocytosis, thrombocytopenia, and hemorrhage. Accumulating lymphocytes resembled antigen-experienced lymphocytes, consistent with the maximal resistance of B6.GT CD4+ and CD8 + T cell to activation-induced cell death. More specifically, we show that TRAIL contributes to Fas ligandmediated activation-induced cell death and controls lymphocyte apoptosis in the presence of interferon-γ once antigen stimulation is removed. Furthermore, dysregulated lymphocyte homeostasis results in the production of anti-DNA and rheumatoid factor autoantibodies, as well as antiplatelet IgM and IgG causing thrombocytopenia. Thus, B6.GT mice reveal new roles for TRAIL in lymphocyte homeostasis and autoimmune lymphoproliferative syndromes and are a model of spontaneous idiopathic thrombocytopenia purpura secondary to lymphoproliferative disease. © 2010 by The American Society of Hematology. Source

Parnell G.P.,University of Sydney | McLean A.S.,University of Sydney | Booth D.R.,Institute for Immunology and Allergy Research | Armstrong N.J.,Garvan Institute of Medical Research | And 8 more authors.
Critical Care

Introduction: Diagnosis of severe influenza pneumonia remains challenging because of a lack of correlation between the presence of influenza virus and clinical status. We conducted gene-expression profiling in the whole blood of critically ill patients to identify a gene signature that would allow clinicians to distinguish influenza infection from other causes of severe respiratory failure, such as bacterial pneumonia, and noninfective systemic inflammatory response syndrome.Methods: Whole-blood samples were collected from critically ill individuals and assayed on Illumina HT-12 gene-expression beadarrays. Differentially expressed genes were determined by linear mixed-model analysis and overrepresented biological pathways determined by using GeneGo MetaCore.Results: The gene-expression profile of H1N1 influenza A pneumonia was distinctly different from those of bacterial pneumonia and systemic inflammatory response syndrome. The influenza gene-expression profile is characterized by upregulation of genes from cell-cycle regulation, apoptosis, and DNA-damage-response pathways. In contrast, no distinctive gene-expression signature was found in patients with bacterial pneumonia or systemic inflammatory response syndrome. The gene-expression profile of influenza infection persisted through 5 days of follow-up. Furthermore, in patients with primary H1N1 influenza A infection in whom bacterial co-infection subsequently developed, the influenza gene-expression signature remained unaltered, despite the presence of a superimposed bacterial infection.Conclusions: The whole-blood expression-profiling data indicate that the host response to influenza pneumonia is distinctly different from that caused by bacterial pathogens. This information may speed the identification of the cause of infection in patients presenting with severe respiratory failure, allowing appropriate patient care to be undertaken more rapidly. © 2012 Parnell et al.; licensee BioMed Central Ltd. Source

Rajasuriar R.,Monash University | Rajasuriar R.,University of Malaya | Booth D.,Institute for Immunology and Allergy Research | Solomon A.,Monash University | And 16 more authors.
Journal of Infectious Diseases

Background. Multiple host factors may influence CD4+ T cell reconstitution in human immunodeficiency virus (HIV)-infected patients after suppressive antiretroviral therapy (ART). We hypothesized that residual immune activation and polymorphisms in the interleukin 7 (IL-7) receptor α (IL-7Rα) gene were important for immune recovery. Methods. We examined HIV-infected patients receiving suppressive ART (n = 96) for their IL-7Rα haplotypes and measured levels of lipopolysaccharide (LPS), soluble CD14, and IL-7 in plasma samples collected before and after ART initiation. Levels of soluble IL-7Rα were measured in HIV-infected patients with IL-7Rα haplotype 2 (n = 11) and those without IL-7Rα haplotype 2 (n = 22). Multivariate analysis was used to identify variables associated with faster recovery to CD4+ T cell counts of >500 and >200 cells/μL. Results. Both LPS and soluble CD14 levels were significantly decreased with ART (P < .001 respectively) but remained elevated compared with uninfected controls. In a multivariate analysis, faster recovery to a CD4+ T cell count of >500 cells/μL was significantly associated with higher baseline CD4+ T cell count, younger age, lower pre-ART LPS level, higher pre-ART soluble CD14 level, lower pre-ART IL-7 level, and IL-7Rα haplotype 2 (hazard ratio, 1.50; 95% confidence interval, 1.03-2.19; P = .034). HIV-infected patients with haplotype 2 had significantly lower soluble IL-7Rα levels compared with those of patients without haplotype 2 (P < .001). Conclusion. Both the extent of immune depletion prior to ART and IL-7Rα haplotype 2 are important determinants of time to CD4+ T cell recovery to counts of 1500 cells/μL. © 2010 by the Infectious Diseases Society of America. All rights reserved. Source

Vucic S.,University of Sydney | Burke T.,Institute for Immunology and Allergy Research | Lenton K.,Institute for Immunology and Allergy Research | Ramanathan S.,University of Sydney | And 3 more authors.
Multiple Sclerosis Journal

Background: Gray matter atrophy has been implicated in the development of secondary progressive multiple sclerosis (SPMS). Cortical function may be assessed by transcranial magnetic stimulation (TMS). Determining whether cortical dysfunction was a feature of SPMS could be of pathophysiological significance.Objectives: Consequently, novel paired-pulse threshold tracking TMS techniques were used to assess whether cortical dysfunction was a feature of SPMS.Methods: Cortical excitability studies were undertaken in 15 SPMS, 25 relapsing-remitting MS patients (RRMS) and 66 controls.Results: Short interval intracortical inhibition (SPMS 3.0 ± 2.1%; RRMS 12.8 ± 1.7%, p < 0.01; controls 10.5 ± 0.7%, p < 0.01) and motor evoked potential (MEP) amplitude (SPMS 11.5 ± 2.2%; RRMS 26.3 ± 3.6%, p <0.05; controls 24.7 ± 1.8%, p < 0.01) were reduced in SPMS, while intracortical facilitation (SPMS -5.2 ± 1.9%; RRMS -2.0 ± 1.4, p < 0.05; controls -0.9 ± 0.7, p < 0.01) and resting motor threshold were increased (SPMS 67.5 ± 4.5%; RRMS 56.0 ± 1.5%, p < 0.01; controls 59.0 ± 1.1%, p < 0.001). Further, central motor conduction time was prolonged in SPMS (9.1 ± 1.2 ms, p < 0.001) and RRMS (7.0 ± 0.9 ms, p < 0.05) patients compared with controls (5.5 ± 0.2 ms). The observed changes in cortical function correlated with the Expanded Disability Status Scale.Conclusion: Together, these findings suggest that cortical dysfunction is associated with disability in MS, and documentation of such cortical dysfunction may serve to quantify disease severity in MS. © The Author(s) 2012. Source

Parnell G.P.,University of Sydney | Parnell G.P.,Institute for Immunology and Allergy Research | Tang B.M.,University of Sydney | Nalos M.,University of Sydney | And 4 more authors.

There is currently no reliable tool available to measure immune dysfunction in septic patients in the clinical setting. This proof-of-concept study assesses the potential of gene expression profiling of whole blood as a tool to monitor immune dysfunction in critically ill septic patients. Whole-blood samples were collected daily for up to 5 days from patients admitted to the intensive care unit with sepsis. RNA isolated from whole-blood samples was assayed on Illumina HT-12 gene expression microarrays consisting of 48,804 probes. Microarray analysis identified 3,677 genes as differentially expressed across 5 days between septic patients and healthy controls. Of the 3,677 genes, biological pathway analysis identified 86 genes significantly downregulated in the sepsis patients were present in pathways relating to immune response. These 86 genes correspond to known immune pathways implicated in sepsis, including lymphocyte depletion, reduced T-lymphocyte activation, and deficient antigen presentation. Furthermore, expression levels of these genes correlated with clinical severity, with a significantly greater degree of downregulation found in nonsurvivors compared with survivors. The results show that whole-blood gene expression analysis can capture systemic immune dysfunctions in septic patients. Our study provides an experimental basis to support further study on the use of a gene expression-based assay, to assess immunosuppression, and to guide immunotherapy in future clinical trials. © 2013 by the Shock Society. Source

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