Paul J McLaren

University of Manitoba, Winnipeg, Manitoba, Canada

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Publications (10)55.71 Total impact

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    ABSTRACT: To identify novel biomarkers for HIV-1 resistance, including pathways that may be critical in anti-HIV-1 vaccine design, we carried out a gene expression analysis on blood samples obtained from HIV-1 highly exposed seronegatives (HESN) from a commercial sex worker cohort in Nairobi and compared their profiles to HIV-1 negative controls. Whole blood samples were collected from 43 HIV-1 resistant sex workers and a similar number of controls. Total RNA was extracted and hybridized to the Affymetrix HUG 133 Plus 2.0 micro arrays (Affymetrix, Santa Clara CA). Output data was analysed through ArrayAssist software (Agilent, San Jose CA). More than 2,274 probe sets were differentially expressed in the HESN as compared to the control group (fold change ≥1.3; p value ≤0.0001, FDR <0.05). Unsupervised hierarchical clustering of the differentially expressed genes readily distinguished HESNs from controls. Pathway analysis through the KEGG signaling database revealed a majority of the impacted pathways (13 of 15, 87%) had genes that were significantly down regulated. The most down expressed pathways were glycolysis/gluconeogenesis, pentose phosphate, phosphatidyl inositol, natural killer cell cytotoxicity and T-cell receptor signaling. Ribosomal protein synthesis and tight junction genes were up regulated. We infer that the hallmark of HIV-1 resistance is down regulation of genes in key signaling pathways that HIV-1 depends on for infection.
    PLoS ONE 01/2012; 7(1):e30048. · 3.53 Impact Factor
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    ABSTRACT: Studies of human immunodeficiency virus (HIV)-exposed seronegative individuals are crucial to inform vaccine design. In the present study we demonstrated that HIV-exposed seronegative commercial sex workers produce lower levels of proinflammatory cytokines at baseline than HIV-negative control subjects. We also showed that CD4+ T cells of HIV-exposed seronegative commercial sex workers have a characteristically lower level of gene expression that can be seen in differentially expressed genes and systems crucial for HIV replication, such as the T cell receptor pathway and previously identified HIV dependency factors. This apparent lowered activation results in a phenomenon we term "immune quiescence," which may contribute to host resistance to HIV.
    The Journal of Infectious Diseases 11/2010; 202 Suppl 3:S339-44. · 5.85 Impact Factor
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    ABSTRACT: Since the late 1980s, with the first identification of individuals who were exposed to human immunodeficiency virus type 1 (HIV-1) yet remained uninfected, or "HIV-1-resistant" individuals, a large number of cohorts that include HIV-exposed seronegative (HESN) subjects have been identified globally for the purpose of investigating the genetic, immunologic, and environmental factors that may help alter susceptibility to HIV-1. In this article, in light of the recent International Symposium on Natural Immunity to HIV, we review the characteristics of different groups with respect to their relative risks and briefly summarize the known cohorts that include exposed uninfected subjects worldwide.
    The Journal of Infectious Diseases 11/2010; 202 Suppl 3:S377-81. · 5.85 Impact Factor
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    ABSTRACT: Since the late 1980s, with the first identification of individuals who were exposed to human immunodeficiency virus type 1 (HIV-1) yet remained uninfected, or “HIV-1–resistant” individuals, a large number of cohorts that include HIV-exposed seronegative (HESN) subjects have been identified globally for the purpose of investigating the genetic, immunologic, and environmental factors that may help alter susceptibility to HIV- 1. In this article, in light of the recent International Symposium on Natural Immunity to HIV, we review the characteristics of different groups with respect to their relative risks and briefly summarize the known cohorts that include exposed uninfected subjects worldwide. Yes Yes
    The Journal of Infectious Diseases 01/2010; · 5.85 Impact Factor
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    ABSTRACT: Human immunodeficiency virus (HIV)-resistant commercial sex workers provide a unique opportunity to study correlates of protection associated with natural resistance to HIV infection. Emerging data from studies of these individuals and other uninfected individuals who have been exposed to HIV suggest that low levels of immune activation may contribute to protection against infection. In the present study, HIV-resistant individuals were shown to have reduced frequencies of T cells expressing the activation marker CD69. They were also found to have elevated frequencies of regulatory T (T(reg)) cells, compared with HIV-negative control individuals. By controlling levels of T cell activation, T(reg) cells may contribute to HIV resistance by minimizing the pool of cells susceptible to infection.
    The Journal of Infectious Diseases 04/2009; 199(9):1318-22. · 5.85 Impact Factor
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    ABSTRACT: Regulatory T cells, a subset of CD4(+) T lymphocytes, play a pivotal role in the maintenance of the balance between the tissue-damaging and protective effects of the immune response. These cells have immunosuppressive function and have been intensely studied in the context of autoimmunity, cancer, allergies, asthma, and infectious diseases. Their role in chronic and persistent viral infections is well appreciated. In acute viral infections, the function of these cells is still unclear. The host and pathogen factors that control the generation and activity of regulatory T cells and the role of these cells in modulating expansion, contraction, and development of immune memory in acute respiratory virus infection need to be further elucidated.
    Clinical Infectious Diseases 05/2008; 46(7):1046-52. · 9.37 Impact Factor
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    ABSTRACT: To determine the correlation between polymorphisms in the IL-4 gene cluster and resistance to HIV-1 infection. : A cross-sectional genetic analysis of polymorphisms within the IL-4 gene cluster was conducted in a well-described female sex worker cohort from Nairobi, Kenya, known to exhibit differential susceptibility to HIV-1 infection. Microsatellite genotyping was used to screen six microsatellite markers in the IL-4 gene cluster for associations with HIV-1 resistance. Further analysis of the interferon regulatory factor 1 (IRF-1) gene was conducted by genomic sequencing. Associations between IRF-1 gene polymorphisms and the HIV-1 resistance phenotype were determined using the chi-square test and Kaplan-Meier survival analysis. The functional consequence of IRF-1 polymorphism was conducted by quantitative Western blot. Three polymorphisms in IRF-1, located at 619, the microsatellite region and 6516 of the gene, showed associations with resistance to HIV-1 infection. The 619A, 179 at IRF-1 microsatellite and 6516G alleles were associated with the HIV-1-resistant phenotype and a reduced likelihood of seroconversion. Peripheral blood mononuclear cells from patients with protective IRF-1 genotypes exhibited significantly lower basal IRF-1 expression and reduced responsiveness to exogenous IFN-gamma stimulation. Polymorphisms in the IRF-1 gene are associated with resistance to infection by HIV-1 and a lowered level of IRF-1 protein expression. This study adds IRF-1, a transcriptional immunoregulatory gene, to the list of genetic correlates of altered susceptibility to HIV-1. This is the first report suggesting that a viral transcriptional regulator might contribute to resistance to HIV-1. Further functional analysis on the role of IRF-1 polymorphisms and HIV-1 resistance is underway.
    AIDS 06/2007; 21(9):1091-101. · 6.41 Impact Factor
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    ABSTRACT: HIV diversity may limit the breadth of vaccine coverage due to epitope sequence differences between strains. Although amino acid substitutions within CD8(+) T cell HIV epitopes can result in complete or partial abrogation of responses, this has primarily been demonstrated in effector CD8(+) T cells. In an HIV-infected Kenyan cohort, we demonstrate that the cross-reactivity of HIV epitope variants differs dramatically between overnight IFN-gamma and longer-term proliferation assays. For most epitopes, particular variants (not the index peptide) were preferred in proliferation in the absence of corresponding overnight IFN-gamma responses and in the absence of the variant in the HIV quasispecies. Most proliferating CD8(+) T cells were polyfunctional via cytokine analyses. A trend to positive correlation was observed between proliferation (but not IFN-gamma) and CD4 counts. We present findings relevant to the assessment of HIV vaccine candidates and toward a better understanding of how viral diversity is tolerated by central and effector memory CD8(+) T cells.
    The Journal of Immunology 04/2007; 178(6):3750-6. · 5.52 Impact Factor
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    ABSTRACT: Advances in microarray technology have allowed for the monitoring of thousands of genes simultaneously. This technology is of particular interest to immunologists studying infectious diseases, because it provides tremendous potential for investigating host-pathogen interactions at the level of immune gene expression. To date, many studies have focused either on cell lines, where the physiological relevance is questionable, or on mixed cell populations, where the contributions of individual subpopulations are unknown. In the present study, we perform an intrasubject comparison of antigen-stimulated immune gene expression profiles between a mixed population of peripheral blood mononuclear cells (PBMC) and the two predominant cell types found in PBMC, CD4+ and CD8+ T lymphocytes. We show that the microarray profiles of CD4+ and CD8+ T lymphocytes differ from each other as well as from that of the mixed cell population. The independence of the gene expression profiles of different cell types is demonstrated with a ubiquitous antigen (Candida albicans) as well as with a disease-specific antigen (human immunodeficiency virus p24). This study has important implications for microarray studies of host immunity and underscores the importance of profiling the expression of specific cell types.
    Clinical and Diagnostic Laboratory Immunology 10/2004; 11(5):977-82. · 2.51 Impact Factor
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    ABSTRACT: DNA microarray profiling of CD4(+) and CD8(+) cells from non-treated relapsing and remitting multiple sclerosis (MS) patients determined that the cytoplasmic binding partner of fragile X protein (CYFIP2, also called PIR121) was increased significantly compared to healthy controls. Western analysis confirmed that CYFIP2 protein was increased approximately fourfold in CD4(+) cells from MS compared to inflammatory bowel disorder (IBD) patients or healthy controls. Because CYFIP2 acts as part of a tetrameric complex that regulates WAVE1 activation we hypothesized that high levels of CYFIP2 facilitate T cell adhesion, which is elevated in MS patients. Several findings indicated that increased levels of CYFIP2 facilitated adhesion. First, adenoviral-mediated overexpression of CYFIP2 in Jurkat cells increased fibronectin-mediated adhesion. Secondly, CYFIP2 knock-down experiments using antisense oligodeoxynucleotides reduced fibronectin-mediated binding in Jurkat and CD4(+) cells. Thirdly, inhibition of Rac-1, a physical partner with CYFIP2 and regulator of WAVE1 activity, reduced fibronectin-mediated adhesion in Jurkat and CD4(+) cells. Finally, inhibition of Rac-1 or reduction of CYFIP2 protein decreased fibronectin-mediated adhesion in CD4(+) cells from MS patients to levels similar to controls. These studies suggest that overabundance of CYFIP2 protein facilitates increased adhesion properties of T cells from MS patients.
    European Journal of Immunology 05/2004; 34(4):1217-27. · 4.97 Impact Factor

Publication Stats

250 Citations
55.71 Total Impact Points

Institutions

  • 2004–2012
    • University of Manitoba
      • Department of Medical Microbiology and Infectious Diseases
      Winnipeg, Manitoba, Canada
  • 2009
    • University of Nairobi
      • Department of Medical Microbiology
      Nairobi, Nairobi Province, Kenya