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Ismail SD, Pankrac J, Ndashimye E, Prodger JL, Abrahams MR, Mann JFS, Redd AD, Arts EJ. Addressing an HIV cure in LMIC. Retrovirology 2021; 18:21. [PMID: 34344423 PMCID: PMC8330180 DOI: 10.1186/s12977-021-00565-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/19/2021] [Indexed: 12/15/2022] Open
Abstract
HIV-1 persists in infected individuals despite years of antiretroviral therapy (ART), due to the formation of a stable and long-lived latent viral reservoir. Early ART can reduce the latent reservoir and is associated with post-treatment control in people living with HIV (PLWH). However, even in post-treatment controllers, ART cessation after a period of time inevitably results in rebound of plasma viraemia, thus lifelong treatment for viral suppression is indicated. Due to the difficulties of sustained life-long treatment in the millions of PLWH worldwide, a cure is undeniably necessary. This requires an in-depth understanding of reservoir formation and dynamics. Differences exist in treatment guidelines and accessibility to treatment as well as social stigma between low- and-middle income countries (LMICs) and high-income countries. In addition, demographic differences exist in PLWH from different geographical regions such as infecting viral subtype and host genetics, which can contribute to differences in the viral reservoir between different populations. Here, we review topics relevant to HIV-1 cure research in LMICs, with a focus on sub-Saharan Africa, the region of the world bearing the greatest burden of HIV-1. We present a summary of ART in LMICs, highlighting challenges that may be experienced in implementing a HIV-1 cure therapeutic. Furthermore, we discuss current research on the HIV-1 latent reservoir in different populations, highlighting research in LMIC and gaps in the research that may facilitate a global cure. Finally, we discuss current experimental cure strategies in the context of their potential application in LMICs.
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Affiliation(s)
- Sherazaan D Ismail
- Division of Medical Virology, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, 7925, South Africa
| | - Joshua Pankrac
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A5C1, Canada
| | - Emmanuel Ndashimye
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A5C1, Canada
- Center for AIDS Research Uganda Laboratories, Joint Clinical Research Centre, Kampala, Uganda
| | - Jessica L Prodger
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A5C1, Canada
- Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Melissa-Rose Abrahams
- Division of Medical Virology, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, 7925, South Africa
| | - Jamie F S Mann
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A5C1, Canada
- Bristol Veterinary School, University of Bristol, Langford House, Langford, Bristol, BS40 5DU, UK
| | - Andrew D Redd
- Division of Medical Virology, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, 7925, South Africa
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Laboratory of Immunoregulation, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, USA
| | - Eric J Arts
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A5C1, Canada.
- Division of Infectious Diseases, Department of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA.
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Liu AY, De Rosa SC, Guthrie BL, Choi RY, Kerubo-Bosire R, Richardson BA, Kiarie J, Farquhar C, Lohman-Payne B. High background in ELISpot assays is associated with elevated levels of immune activation in HIV-1-seronegative individuals in Nairobi. IMMUNITY INFLAMMATION AND DISEASE 2018; 6:392-401. [PMID: 29974672 PMCID: PMC6113767 DOI: 10.1002/iid3.231] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 06/14/2018] [Accepted: 06/18/2018] [Indexed: 01/18/2023]
Abstract
INTRODUCTION Spontaneous interferon-γ (IFNγ) released detected by enzyme-linked immunospot (ELISpot) assays may be a biological phenomenon. Markers of immune activation levels were assessed as correlates of high background among individuals in Kenya. METHODS Couples concordantly seronegative for HIV-1 were enrolled. IFN-γ ELISpot assays were conducted and negative control wells were categorized as having either high or low background (≥50 and <50 SFU/106 peripheral blood mononuclear cells [PBMC], respectively). PBMC were stained for CD4, CD8, and immune activation markers (CD38 and HLA-DR) and analyzed using flow cytometry. Proportions of activated T-cells were compared between those with low and high background by Mann-Whitney U test. Correlates of background SFU and immune activation were assessed using regression models. RESULTS Among 58 individuals, 14 (24%) had high background. Frequencies of CD4+ CD38+ HLA-DR+ and CD8+ CD38+ HLA-DR+ cells were higher in individuals with high background compared to those with low background (P = 0.02). Higher background SFU was associated with history of sexually transmitted infections (P = 0.03), and illness in the past 3 months (P = 0.005), in addition to increased levels of activated CD4+ and CD8+ cells (P range = 0.008-0.03). Female gender and male circumcision decreased levels of CD4+ and CD8+ immune activation (P range = 0.002-0.03). Additionally, higher background SFU and activated CD4+ and CD8+ cells were individually associated with positive ELISpot responses to HIV-1 peptide pools (P range = 0.01-0.03). CONCLUSIONS These findings suggest that increased basal immune responses may be a biological mechanism contributing to higher background ELISpot SFU. Systematic exclusion of data from individuals with increased background in IFN-γ release assays may bias results in population-based studies.
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Affiliation(s)
- Amy Y Liu
- Department of Epidemiology, University of Washington, Seattle, Washington, USA
| | - Stephen C De Rosa
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, USA.,Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Brandon L Guthrie
- Department of Epidemiology, University of Washington, Seattle, Washington, USA
| | - Robert Y Choi
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Rose Kerubo-Bosire
- Centre for Public Health Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Barbra A Richardson
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.,Department of Global Health, University of Washington, Seattle, Washington, USA.,Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - James Kiarie
- Department of Obstetrics and Gynaecology, Kenyatta National Hospital, Nairobi, Kenya
| | - Carey Farquhar
- Department of Epidemiology, University of Washington, Seattle, Washington, USA.,Department of Medicine, University of Washington, Seattle, Washington, USA.,Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Barbara Lohman-Payne
- Department of Medicine, University of Washington, Seattle, Washington, USA.,Department of Global Health, University of Washington, Seattle, Washington, USA.,Department of Paediatrics and Child Health, University of Nairobi, Nairobi, Kenya
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Omollo K, Boily-Larouche G, Lajoie J, Kimani M, Cheruiyot J, Kimani J, Oyugi J, Fowke KR. The Impact of Sex Work Interruption on Blood-Derived T Cells in Sex Workers from Nairobi, Kenya. AIDS Res Hum Retroviruses 2016; 32:1072-1078. [PMID: 26879184 PMCID: PMC5067831 DOI: 10.1089/aid.2015.0332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Unprotected sexual intercourse exposes the female genital tract (FGT) to semen-derived antigens, which leads to a proinflammatory response. Studies have shown that this postcoital inflammatory response can lead to recruitment of activated T cells to the FGT, thereby increasing risk of HIV infection. OBJECTIVE The purpose of this study was to evaluate the impact of sex work on activation and memory phenotypes of peripheral T cells among female sex workers (FSW) from Nairobi, Kenya. SUBJECTS Thirty FSW were recruited from the Pumwani Sex Workers Cohort, 10 in each of the following groups: HIV-exposed seronegative (at least 7 years in active sex work), HIV positive, and New Negative (HIV negative, less than 3 years in active sex work). Blood was obtained at three different phases (active sex work, abstinence from sex work-sex break, and following resumption of sex work). Peripheral blood mononuclear cells were isolated and stained for phenotypic markers (CD3, CD4, CD8, and CD161), memory phenotype markers (CD45RA and CCR7), activation markers (CD69, HLA-DR, and CD95), and the HIV coreceptor (CCR5). T-cell populations were compared between groups. RESULTS In HIV-positive women, CD8+CCR5+ T cells declined at the sex break period, while CD4+CD161+ T cells increased when returning to sex work. All groups showed no significant changes in systemic T-cell activation markers following the interruption of sex work, however, significant reductions in naive CD8+ T cells were noted. For each of the study points, HIV positives had higher effector memory and CD8+CD95+ T cells and lower naive CD8+ T cells than the HIV-uninfected groups. CONCLUSIONS Interruption of sex work had subtle effects on systemic T-cell memory phenotypes.
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Affiliation(s)
- Kenneth Omollo
- Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya
| | | | - Julie Lajoie
- Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya
- Department of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Makobu Kimani
- Kenyan AIDS Control Program, University of Nairobi, Nairobi, Kenya
| | | | - Joshua Kimani
- Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya
- Kenyan AIDS Control Program, University of Nairobi, Nairobi, Kenya
| | - Julius Oyugi
- Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya
- Kenyan AIDS Control Program, University of Nairobi, Nairobi, Kenya
| | - Keith Raymond Fowke
- Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya
- Department of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Community Health Science, University of Manitoba, Winnipeg, Manitoba, Canada
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Kaul R, Prodger J, Joag V, Shannon B, Yegorov S, Galiwango R, McKinnon L. Inflammation and HIV Transmission in Sub-Saharan Africa. Curr HIV/AIDS Rep 2016; 12:216-22. [PMID: 25877253 DOI: 10.1007/s11904-015-0269-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While the per-contact risk of sexual HIV transmission is relatively low, it is fourfold higher in sub-Saharan Africa, and this may partly explain the major global disparities that exist in HIV prevalence. Genital immune parameters are key determinants of HIV transmission risk, including epithelial integrity and the presence of highly HIV-susceptible intraepithelial or submucosal CD4+ T cell target cells. Biological parameters that may enhance mucosal HIV susceptibility in highly HIV-affected regions of sub-Saharan Africa include increased levels of mucosal inflammation, which can affect both epithelial integrity and target cell availability, as well as the increased mucosal surface area that is afforded by an intact foreskin, contraceptive choices, and intravaginal practices. There are multifactorial causes for increased mucosal inflammation, with the prevalence and nature of common co-infections being particularly relevant.
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Affiliation(s)
- Rupert Kaul
- Departments of Medicine and Immunology, University of Toronto, Medical Sciences Building Rm. 6356, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada,
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Juno JA, Stalker AT, Waruk JL, Oyugi J, Kimani M, Plummer FA, Kimani J, Fowke KR. Elevated expression of LAG-3, but not PD-1, is associated with impaired iNKT cytokine production during chronic HIV-1 infection and treatment. Retrovirology 2015; 12:17. [PMID: 25810006 PMCID: PMC4332911 DOI: 10.1186/s12977-015-0142-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 01/16/2015] [Indexed: 01/08/2023] Open
Abstract
Background LAG-3 is a potent negative regulator of the immune response but its impact in HIV infection in poorly understood. Unlike exhaustion markers such as PD-1, Tim-3, 2B4 and CD160, LAG-3 is poorly expressed on bulk and antigen-specific T cells during chronic HIV infection and its expression on innate lymphocyte subsets is not well understood. The aim of this study was to assess LAG-3 expression and association with cellular dysfunction on T cells, NK cells and iNKT cells among a cohort of healthy and HIV-infected female sex workers in Nairobi, Kenya. Results Ex vivo LAG-3 expression was measured by multiparametric flow cytometry, and plasma cytokine/chemokine concentrations measured by bead array. Although LAG-3 expression on bulk T cells was significantly increased among HIV-infected women, the proportion of cells expressing the marker was extremely low. In contrast, LAG-3 was more highly expressed on NK and iNKT cells and was not reduced among women treated with ART. To assess the functional impact of LAG-3 on iNKT cells, iNKT cytokine production was measured in response to lipid (αGalCer) and PMA/Io stimulation by both flow cytometry and cytokine bead array. iNKT cytokine production is profoundly altered by both HIV infection and treatment, and LAG-3, but not PD-1, expression is associated with a reduction in iNKT IFNγ production. Conclusions LAG-3 does not appear to mediate T cell exhaustion in this African population, but is instead expressed on innate lymphocyte subsets including iNKT cells. HIV infection alters iNKT cytokine production patterns and LAG-3 expression is uniquely associated with iNKT dysfunction. The continued expression of LAG-3 during treatment suggests it may contribute to the lack of innate immune reconstitution commonly observed during ART. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0142-z) contains supplementary material, which is available to authorized users.
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Johnston RE, Heitzeg MM. Sex, age, race and intervention type in clinical studies of HIV cure: a systematic review. AIDS Res Hum Retroviruses 2015; 31:85-97. [PMID: 25313793 DOI: 10.1089/aid.2014.0205] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
This systematic review was undertaken to determine the extent to which adult subjects representing sex (female), race (nonwhite), and age (>50 years) categories are included in clinical studies of HIV curative interventions and thus, by extension, the potential for data to be analyzed that may shed light on the influence of such demographic variables on safety and/or efficacy. English-language publications retrieved from PubMed and from references of retrieved papers describing clinical studies of curative interventions were read and demographic, recruitment year, and intervention-type details were noted. Variables of interest included participation by sex, age, and race; changes in participation rates by recruitment year; and differences in participation by intervention type. Of 151 publications, 23% reported full demographic data of study enrollees, and only 6% reported conducting efficacy analyses by demographic variables. Included studies recruited participants from 1991 to 2011. No study conducted safety analyses by demographic variables. The representation of women, older people, and nonwhites did not reflect national or international burdens of HIV infection. Participation of demographic subgroups differed by intervention type and study location. Rates of participation of demographic groups of interest did not vary with time. Limited data suggest efficacy, particularly of early therapy initiation followed by treatment interruption, may vary by demographic variables, in this case sex. More data are needed to determine associations between demographic characteristics and safety/efficacy of curative interventions. Studies should be powered to conduct such analyses and cure-relevant measures should be standardized.
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Affiliation(s)
| | - Mary M. Heitzeg
- Department of Psychiatry, University of Michigan, Ann Arbor, Michigan
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Clade A HIV-1 Gag-specific T cell responses are frequent but do not correlate with viral loads in a cohort of treatment-naive HIV-infected individuals living in Guinea-Bissau. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:1999-2001. [PMID: 23081817 DOI: 10.1128/cvi.00399-12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Thayil SM, Ho YC, Bollinger RC, Blankson JN, Siliciano RF, Karakousis PC, Page KR. Mycobacterium tuberculosis complex enhances susceptibility of CD4 T cells to HIV through a TLR2-mediated pathway. PLoS One 2012; 7:e41093. [PMID: 22844428 PMCID: PMC3402510 DOI: 10.1371/journal.pone.0041093] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/18/2012] [Indexed: 01/19/2023] Open
Abstract
Among HIV-infected individuals, co-infection with Mycobacterium tuberculosis is associated with faster progression to AIDS. We investigated the hypothesis that M. bovis BCG and M. tuberculosis (Mtb complex) could enhance susceptibility of CD4+ cells to HIV infection. Peripheral blood mononuclear cells (PBMCs) collected from healthy donors were stimulated with M. bovis BCG, M. tuberculosis CDC1551 and M. smegmatis MC2155, and stimulated CD4+ cells were infected with R5-and X4-tropic single replication-competent pseudovirus. CD4+ cells stimulated with Mtb complex showed enhanced infection with R5- and X4-tropic HIV, compared to unstimulated cells or cells stimulated with M. smegmatis (p<0.01). Treatment with TLR2 siRNA reversed the increased susceptibility of CD4+ cells with R5- and X4-tropic virus induced by Mtb complex. These findings suggest that TB infection and/or BCG vaccination may be a risk factor for HIV acquisition.
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Affiliation(s)
- Seema M. Thayil
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Ya-Chi Ho
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Robert C. Bollinger
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Joel N. Blankson
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Robert F. Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Petros C. Karakousis
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
| | - Kathleen R. Page
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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Tiba F, Nauwelaers F, Sangaré L, Coulibaly B, Kräusslich HG, Böhler T. Activation and maturation of peripheral blood T cells in HIV-1-infected and HIV-1-uninfected adults in Burkina Faso: a cross-sectional study. J Int AIDS Soc 2011; 14:57. [PMID: 22177276 PMCID: PMC3281784 DOI: 10.1186/1758-2652-14-57] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 12/17/2011] [Indexed: 11/18/2022] Open
Abstract
Background We wanted to explore to what extent environmental exposure to immune stimulants, which is expected to be more present in rural than in urban settings, influences T cell activation and maturation in healthy and in HIV-1-infected individuals in Burkina Faso in west Africa. Methods The proportion of circulating naïve T cells and the expression of the T cell activation markers, CD95 and CD38, were analyzed by immunophenotyping and three-colour flow cytometry in 63 healthy individuals and 137 treatment-naïve HIV-1-infected subjects from Ouagadougou (urban setting) and 26 healthy adults and 61 treatment-naïve patients from Nouna (rural). Results A slightly higher activation level of CD4+ and CD8+ peripheral blood T cells was seen in healthy adults living in Nouna than in those living in Ouagadougou. The percentages of naïve CD45RAbright CCR7+ T cells were not significantly different between both study sites. Taking into consideration that relatively more HIV-1-infected patients in Nouna were in an advanced disease stage, no relevant differences were seen in T cell activation and maturation between patients at both study sites. As expected, the percentage of CD95+ CD4+ and CD38+ CD8+ T cells and the respective antigen density on these cells was significantly higher in patients than in controls in both settings. The percentage of naïve CD8+ T cells was lower in HIV-1-infected subjects than in healthy controls irrespective of the study site, while a lower proportion of naïve CD4+ T cells in patients compared with controls was seen only in Nouna. Conclusions Environmentally triggered immune activation may contribute to the increased expression of the activation markers CD95 and CD38 on peripheral blood T cells from healthy adults living in rural versus urban settings in Burkina Faso. T cell activation is further increased in HIV-1-infected individuals due to T cell loss and high plasma viral load levels. The observed variations in T cell activation levels or the proportion of naïve T cells in our study patients, however, are not explained by differences in CD4+ T cell counts or HIV-1 plasma viral load levels alone.
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Affiliation(s)
- Fabrice Tiba
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | | | - Lassana Sangaré
- Centre Hospitalier Universitaire Yalgado Ouedraogo, Ouagadougou, Burkina Faso
| | | | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | - Thomas Böhler
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
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The role of SNPs in the α-chain of the IL-7R gene in CD4+ T-cell recovery in HIV-infected African patients receiving suppressive cART. Genes Immun 2011; 13:83-93. [DOI: 10.1038/gene.2011.65] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Mendelian randomization: potential use of genetics to enable causal inferences regarding HIV-associated biomarkers and outcomes. Curr Opin HIV AIDS 2011; 5:545-59. [PMID: 20978399 DOI: 10.1097/coh.0b013e32833f2087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW It is unknown whether biomarkers simply correlate with or are causal for HIV-associated outcomes. Mendelian randomization is a genetic epidemiologic approach used to disentangle causation from association. Here, we discuss the potential use of Mendelian randomization for differentiating whether biomarkers are correlating with or causal for HIV-associated outcomes. RECENT FINDINGS Mendelian randomization refers to the random allocation of alleles at the time of gamete formation. In observational epidemiology, this refers to the use of genetic variants to estimate a causal effect between a modifiable risk factor and an outcome of interest. A formal Mendelian randomization study using a genetic marker as a proxy for the biomarker has not been conducted in the HIV field. However, in the postgenomic era, this approach is being used increasingly. Examples are evidence for the causal role of BMI in blood pressure and noncausal role of C-reactive protein in coronary heart disease. We discuss the conceptual framework, uses, and limitations of Mendelian randomization in the context of HIV infection as well as specific biomarkers (IL-6, C-reactive protein) and genetic determinants (e.g., in CCR5, chemokine, and DARC genes) that associate with HIV-related outcomes. SUMMARY Making the distinction between correlation and causality has particular relevance when a biomarker (e.g., IL-6) is potentially modifiable, in which case a biomarker-guided targeted treatment strategy may be feasible. Although the tenets of Mendelian randomization rest on strong assumptions, and conducting a Mendelian randomization study in HIV infection presents many challenges, it may offer the potential to identify causal biomarkers for HIV-associated outcomes.
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Kaul R, Cohen CR, Chege D, Yi TJ, Tharao W, McKinnon LR, Remis R, Anzala O, Kimani J. Biological factors that may contribute to regional and racial disparities in HIV prevalence. Am J Reprod Immunol 2011; 65:317-24. [PMID: 21223426 DOI: 10.1111/j.1600-0897.2010.00962.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Despite tremendous regional and subregional disparities in HIV prevalence around the world, epidemiology consistently demonstrates that black communities have been disproportionately affected by the pandemic. There are many reasons for this, and a narrow focus on socio-behavioural causes may be seen as laying blame on affected communities or individuals. HIV sexual transmission is very inefficient, and a number of biological factors are critical in determining whether an unprotected sexual exposure to HIV results in productive infection. This review will focus on ways in which biology, rather than behaviour, may contribute to regional and racial differences in HIV epidemic spread. Specific areas of focus are viral factors, host genetics, and the impact of co-infections and host immunology. Considering biological causes for these racial disparities may help to destigmatize the issue and lead to new and more effective strategies for prevention.
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Affiliation(s)
- Rupert Kaul
- Department of Medicine, University of Toronto, 1 King’s College Circle, Toronto, Ontario, Canada.
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Awah FM, Uzoegwu PN, Oyugi JO, Rutherford J, Ifeonu P, Yao XJ, Fowke KR, Eze MO. Free radical scavenging activity and immunomodulatory effect of Stachytarpheta angustifolia leaf extract. Food Chem 2010. [DOI: 10.1016/j.foodchem.2009.09.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Steel A, John L, Shamji MH, Henderson DC, Gotch FM, Gazzard BG, Kelleher P. CD38 expression on CD8 T cells has a weak association with CD4 T-cell recovery and is a poor marker of viral replication in HIV-1-infected patients on antiretroviral therapy. HIV Med 2008; 9:118-25. [PMID: 18257774 DOI: 10.1111/j.1468-1293.2007.00528.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE The aim of the study was to determine whether the expression of CD38 on CD8 T cells can identify patients with virological failure on antiretroviral therapy (ART). DESIGN This was a cross-sectional study of patients attending a single HIV clinic in London. METHODS The expression of CD38 on CD8 T cells was assessed using a biologically calibrated flow cytometry protocol. Patients were characterized by lymphocyte subset and viral load measurements. Characteristics including historical CD4 T cell counts, therapeutic history, co-infections and demographics were obtained from medical records. RESULTS Elevated levels of CD8 CD38(high) T cells were found in HIV-1-infected patients who failed to suppress viral replication with ART; however, this parameter lacked sufficient sensitivity and specificity to replace viral load testing in assessing the efficacy of ART. Increased levels of CD8 CD38(high) cells were associated with reduced CD4 T cell counts in HIV-1-infected patients on ART after correcting for known determinants of CD4 T-cell recovery. CONCLUSIONS The expression of CD38 on CD8 T cells lacks sufficient sensitivity and specificity to be used as a surrogate marker for viral load to monitor HIV-1 infection. T-cell activation is associated with reduced CD4 T-cell reconstitution in patients receiving ART.
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Affiliation(s)
- A Steel
- Department of Immunology, Imperial College, Chelsea & Westminster Hospital, London, UK
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Abstract
OBJECTIVES Toll-like receptors (TLR) are important in pathogen recognition and may play a role in HIV disease. We evaluated the effect of chronic untreated and treated HIV-1 infection on systemic TLR expression and TLR signalling. METHODS Two hundred HIV-infected and uninfected women from a Kenya cohort participated in the studies. TLR1 to TLR10 messenger RNA expression was determined by quantitative reverse transcriptase polymerase chain reaction in peripheral blood mononuclear cells (PBMC). TLR ligand responsiveness was determined in or using ex-vivo PBMC by cytokine production in culture supernatants. RESULTS Chronic, untreated HIV-1 infection was significantly associated with increased mRNA expression of TLR6, TLR7, and TLR8 and when analysis was limited to those with advanced disease (CD4 cell count < 200 cells/ml) TLR2, TLR3, and TLR4 were additionally elevated. TLR expression correlated with the plasma HIV-RNA load, which was significant for TLR6 and TLR7. In vitro HIV single-stranded RNA alone could enhance TLR mRNA expression. PBMC of HIV-infected subjects also demonstrated profoundly increased proinflammatory responsiveness to TLR ligands, suggesting sensitization of TLR signalling in HIV. Finally, viral suppression by HAART was associated with a normalization of TLR levels. CONCLUSION Together, these data indicate that chronic viraemic HIV-1 is associated with increased TLR expression and responsiveness, which may perpetuate innate immune dysfunction and activation that underlies HIV pathogenesis, and thus reveal potential new targets for therapy.
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Koesters SA, Alimonti JB, Wachihi C, Matu L, Anzala O, Kimani J, Embree JE, Plummer FA, Fowke KR. IL-7Ralpha expression on CD4+ T lymphocytes decreases with HIV disease progression and inversely correlates with immune activation. Eur J Immunol 2006; 36:336-44. [PMID: 16421946 DOI: 10.1002/eji.200535111] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many factors can influence the rate of HIV disease progression, including those that maintain T cell homeostasis. One key homeostatic regulator is the IL-7 receptor (IL-7R). Previous studies have shown IL-7R expression levels decrease in HIV infection, but effects on memory subtypes, CD4(+) T cells, and cell function have not been explored. The present study examined the expression of the IL-7Ralpha chain on naïve and memory T lymphocyte subsets of both HIV-positive and HIV-negative individuals from Nairobi, Kenya to assess the role of IL-7Ralpha in HIV disease. Expression of IL-7Ralpha was significantly reduced in all CD4(+) and CD8(+) T cell subsets in HIV-positive individuals. This reduction was further enhanced in those with advanced HIV progression. Expression of IL-7Ralpha was inversely correlated to immune activation, and apoptosis, and was positively correlated with CD4 count in both bivariate and multivariate analysis. Expression of IL-7Ralpha did not correlate with HIV viral loads, indicating the elevated immune activation seen in HIV-infected individuals may be impacting expression of IL-7Ralpha, independent of viral loads. Signaling via the IL-7R is essential for T cell homeostasis and maintenance of T cell memory. Reduction of this receptor may contribute to the homeostatic disruption seen in HIV.
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Affiliation(s)
- Sandra A Koesters
- Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada, R3E 0 W3
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Hanson A, Sarr AD, Shea A, Jones N, Mboup S, Kanki P, Cao H. Distinct profile of T cell activation in HIV type 2 compared to HIV type 1 infection: differential mechanism for immunoprotection. AIDS Res Hum Retroviruses 2005; 21:791-8. [PMID: 16218803 DOI: 10.1089/aid.2005.21.791] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The mechanism for the lower rate of disease progression in HIV-2 infection remains undefined. We evaluated T cell activation in a cohort of HIV-infected commercial sex workers in Dakar, Senegal. CD8+ T cell activation was significantly lower in HIV-2- compared to HIV-1-infected volunteers and both groups displayed higher activation levels compared to seronegative individuals. In contrast, CD4+ T cell activation was similar between the HIV-1 and HIV-2 groups and significantly higher compared to the seronegative group. Interestingly, HIV-2-positive volunteers with evidence of Gag-specific CD8+ T cell responses displayed lower CD4+ T cell activation. Our data suggest that the distinct T cell activation profile in HIV-2-positive individuals may reflect on the presence of effective host immune responses in HIV-2 infection.
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Affiliation(s)
- Andrea Hanson
- California Department of Health Services, Richmond, California 94804, USA
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