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Papers by Elizabeth Sinclair

Research paper thumbnail of Human Immunodeficiency Virus Persistence and Production in T-Cell Development

Clinical and Vaccine Immunology, 2006

Human immunodeficiency virus type 1 (HIV-1) replication depends on CD4 and coreceptor expression ... more Human immunodeficiency virus type 1 (HIV-1) replication depends on CD4 and coreceptor expression as well as host factors associated with the activation state of the cell. To determine the impact of the activation stage of thymocytes on the HIV-1 life cycle, we investigated R5 and X4 HIV-1 entry, reverse transcription, and expression in discrete thymocyte subsets at different stages of T-cell development. Early after infection, preferential entry and replication of R5 HIV-1 were predominantly detected in mature CD3+/hi CD27+ thymocytes. Thus, R5 HIV-1 targets the stage of development where thymocytes acquire functional responsiveness, which has important implications for HIV pathogenesis. In contrast, X4 HIV-1 expression and replication were primarily found in immature CD3−/+/low CD27− CD69− thymocytes. HIV-1 proviral burden and virus expression in thymocyte subsets correlated with the expression of the highest levels of the respective coreceptor. R5 and X4 HIV-1 entered and complete...

Research paper thumbnail of CD4+ T Cells Expressing PD-1, TIGIT and LAG-3 Contribute to HIV Persistence during ART

PLoS pathogens, 2016

HIV persists in a small pool of latently infected cells despite antiretroviral therapy (ART). Ide... more HIV persists in a small pool of latently infected cells despite antiretroviral therapy (ART). Identifying cellular markers expressed at the surface of these cells may lead to novel therapeutic strategies to reduce the size of the HIV reservoir. We hypothesized that CD4+ T cells expressing immune checkpoint molecules would be enriched in HIV-infected cells in individuals receiving suppressive ART. Expression levels of 7 immune checkpoint molecules (PD-1, CTLA-4, LAG-3, TIGIT, TIM-3, CD160 and 2B4) as well as 4 markers of HIV persistence (integrated and total HIV DNA, 2-LTR circles and cell-associated unspliced HIV RNA) were measured in PBMCs from 48 virally suppressed individuals. Using negative binomial regression models, we identified PD-1, TIGIT and LAG-3 as immune checkpoint molecules positively associated with the frequency of CD4+ T cells harboring integrated HIV DNA. The frequency of CD4+ T cells co-expressing PD-1, TIGIT and LAG-3 independently predicted the frequency of cell...

Research paper thumbnail of Effects of Combined CCR5/Integrase Inhibitors-Based Regimen on Mucosal Immunity in HIV-Infected Patients Naïve to Antiretroviral Therapy: A Pilot Randomized Trial

Research paper thumbnail of Site-Specific Differences in T Cell Frequencies and Phenotypes in the Blood and Gut of HIV-Uninfected and ART-Treated HIV+ Adults

PLOS ONE, 2015

Gastrointestinal T lymphocytes are critical for mucosal immunity and HIV pathogenesis, yet little... more Gastrointestinal T lymphocytes are critical for mucosal immunity and HIV pathogenesis, yet little is known about normal T cell numbers and phenotypes in different regions of the gut, or the degree to which ART can restore levels to those of HIV-uninfected individuals. To investigate these questions, we measured T cell frequencies and markers of memory, activation, anergy, and homing in the blood, ileum, and rectum of HIV-and ART-suppressed HIV+ adults. In HIV-individuals, T cell frequencies and phenotypes differed significantly between sites. Compared to HIV-adults, HIV+ adults had lower absolute CD4+T cell counts in the ileal lamina propria and lower relative CD4+T cell counts in the blood and ileum. In the gut, HIV+ adults had a higher proportion of CD38+ CD4+T cells, a lower proportion of terminallydifferentiated effector cells, and, in the rectum, a higher proportion of CTLA-4+ CD4+T cells. In HIV+ individuals, relative CD4+T cell numbers in the ileum correlated with the proportion of CTLA-4+ CD4+T cells, whereas in the rectum, they tended to correlate with the proportion of circulating CD4+T cells expressing α4β7 or CCR6. Mechanisms of T cell reconstitution may differ throughout the gut, with homing contributing more in the rectum while ileal reconstitution is associated with mucosal CD4+T cell anergy.

Research paper thumbnail of Progressive increase in central nervous system immune activation in untreated primary HIV-1 infection

Journal of Neuroinflammation, 2014

Research paper thumbnail of Limited HIV infection of central memory and stem cell memory CD4+ T cells is associated with lack of progression in viremic individuals

PLoS pathogens, 2014

A rare subset of HIV-infected individuals, designated viremic non-progressors (VNP), remain asymp... more A rare subset of HIV-infected individuals, designated viremic non-progressors (VNP), remain asymptomatic and maintain normal levels of CD4+ T-cells despite persistently high viremia. To identify mechanisms potentially responsible for the VNP phenotype, we compared VNPs (average >9 years of HIV infection) to HIV-infected individuals who have similar CD4+ T-cell counts and viral load, but who are likely to progress if left untreated ("putative…

Research paper thumbnail of Expression profile of host restriction factors in HIV-1 elite controllers

Retrovirology, Jan 16, 2013

Several host-encoded antiviral factors suppress HIV-1 replication in a cell-autonomous fashion in... more Several host-encoded antiviral factors suppress HIV-1 replication in a cell-autonomous fashion in vitro. The relevance of these defenses to the control of HIV-1 in vivo remains to be elucidated. We hypothesized that cellular restriction of HIV-1 replication plays a significant role in the observed suppression of HIV-1 in "elite controllers", individuals who maintain undetectable levels of viremia in the absence of antiretroviral therapy (ART). We comprehensively compared the expression levels of 34 host restriction factors and cellular activation levels in CD4+ T cells and sorted T cell subsets between elite controllers, HIV-1-infected (untreated) non-controllers, ART-suppressed, and uninfected individuals. Expression of schlafen 11, a codon usage-based inhibitor of HIV-1 protein synthesis, was significantly elevated in CD4+ T cells from elite controllers as compared to both non-controllers (p = 0.048) and ART-suppressed individuals (p = 0.024), with this effect most appar...

Research paper thumbnail of HIV-Infected Individuals with Low CD4/CD8 Ratio despite Effective Antiretroviral Therapy Exhibit Altered T Cell Subsets, Heightened CD8+ T Cell Activation, and Increased Risk of Non-AIDS Morbidity and Mortality

PLoS Pathogens, 2014

A low CD4/CD8 ratio in elderly HIV-uninfected adults is associated with increased morbidity and m... more A low CD4/CD8 ratio in elderly HIV-uninfected adults is associated with increased morbidity and mortality. A subset of HIVinfected adults receiving effective antiretroviral therapy (ART) fails to normalize this ratio, even after they achieve normal CD4+ T cell counts. The immunologic and clinical characteristics of this clinical phenotype remain undefined. Using data from four distinct clinical cohorts and three clinical trials, we show that a low CD4/CD8 ratio in HIV-infected adults during otherwise effective ART (after CD4 count recovery above 500 cells/mm 3) is associated with a number of immunological abnormalities, including a skewed T cell phenotype from naïve toward terminally differentiated CD8+ T cells, higher levels of CD8+ T cell activation (HLADR+CD38+) and senescence (CD282 and CD57+CD282), and higher kynurenine/tryptophan ratio. Changes in the peripheral CD4/CD8 ratio are also reflective of changes in gut mucosa, but not in lymph nodes. In a longitudinal study, individuals who initiated ART within six months of infection had greater CD4/CD8 ratio increase compared to later initiators (.2 years). After controlling for age, gender, ART duration, nadir and CD4 count, the CD4/CD8 ratio predicted increased risk of morbidity and mortality. Hence, a persistently low CD4/CD8 ratio during otherwise effective ART is associated with increased innate and adaptive immune activation, an immunosenescent phenotype, and higher risk of morbidity/mortality. This ratio may prove useful in monitoring response to ART and could identify a unique subset of individuals needed of novel therapeutic interventions.

Research paper thumbnail of Prospective Antiretroviral Treatment of Asymptomatic, HIV-1 Infected Controllers

PLoS Pathogens, 2013

The study of HIV-infected ''controllers'' who are able to maintain low levels of plasma HIV RNA i... more The study of HIV-infected ''controllers'' who are able to maintain low levels of plasma HIV RNA in the absence of antiretroviral therapy (ART) may provide insights for HIV cure and vaccine strategies. Despite maintaining very low levels of plasma viremia, controllers have elevated immune activation and accelerated atherosclerosis. However, the degree to which low-level replication contributes to these phenomena is not known. Sixteen asymptomatic controllers were prospectively treated with ART for 24 weeks. Controllers had a statistically significant decrease in ultrasensitive plasma and rectal HIV RNA levels with ART. Markers of T cell activation/dysfunction in blood and gut mucosa also decreased substantially with ART. Similar reductions were observed in the subset of ''elite'' controllers with pre-ART plasma HIV RNA levels below conventional assays (,40 copies/mL). These data confirm that HIV replication persists in controllers and contributes to a chronic inflammatory state. ART should be considered for these individuals (ClinicalTrials.gov NCT01025427).

Research paper thumbnail of Challenges in Detecting HIV Persistence during Potentially Curative Interventions: A Study of the Berlin Patient

PLoS Pathogens, 2013

There is intense interest in developing curative interventions for HIV. How such a cure will be q... more There is intense interest in developing curative interventions for HIV. How such a cure will be quantified and defined is not known. We applied a series of measurements of HIV persistence to the study of an HIV-infected adult who has exhibited evidence of cure after allogeneic hematopoietic stem cell transplant from a homozygous CCR5D32 donor. Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV DNA or RNA was detected in peripheral blood mononuclear cells (PBMC), spinal fluid, lymph node, or terminal ileum, and no replication-competent virus could be cultured from PBMCs. However, HIV RNA was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in ART-suppressed patients. It was not possible to obtain sequence data from plasma or gut, while an X4 sequence from PBMC did not match the pre-transplant sequence. HIV antibody levels were readily detectable but declined over time; T cell responses were largely absent. The occasional, low-level PCR signals raise the possibility that some HIV nucleic acid might persist, although they could also be false positives. Since HIV levels in well-treated individuals are near the limits of detection of current assays, more sensitive assays need to be developed and validated. The absence of recrudescent HIV replication and waning HIV-specific immune responses five years after withdrawal of treatment provide proof of a clinical cure.

Research paper thumbnail of A Low T Regulatory Cell Response May Contribute to Both Viral Control and Generalized Immune Activation in HIV Controllers

Research paper thumbnail of Cytomegalovirus-Specific T Cells Persist at Very High Levels during Long-Term Antiretroviral Treatment of HIV Disease

PLoS ONE, 2010

Background: In healthy, HIV seronegative, CMV seropositive adults, a large proportion of T cells ... more Background: In healthy, HIV seronegative, CMV seropositive adults, a large proportion of T cells are CMV-specific. High-level CMV-specific T cell responses are associated with accelerated immunologic aging (''immunosenesence'') in the elderly population. The impact of untreated and treated HIV infection on the frequency of these cells remains undefined. Methodology/Principal Findings: We measured the proportion of CD4+ and CD8+ T cells responding to CMV pp65 and IE proteins was measured using flow cytometry in 685 unique HIV seronegative and seropositive individuals. The proportion of CMV-specific CD8+ T cells was consistently higher in the HIV-seropositive subjects compared to the HIV-seronegative subjects. This HIV effect was observed even in patients who lacked measurable immunodeficiency. Among the HIVseropositive subjects, CMV-specific CD8+ T cell responses were proportionately lower during recent infection, higher during chronic untreated infection and higher still during long-term antiretroviral treated infection. The CD8+ T cell response to just two CMV proteins (pp65 and IE) was approximately 6% during long-term therapy, which was over twice that seen in HIV-seronegative persons. CMV-specific CD4+ T cell responses followed the same trends, but the magnitude of the effect was smaller. Conclusions/Significance: Long-term successfully treated HIV infected patients have remarkably high levels of CMV-specific effector cells. These levels are similar to that observed in the elderly, but occur at much younger ages. Future studies should focus on defining the potential role of the CMV-specific inflammatory response in non-AIDS morbidity and mortality, including immunosenescence.

Research paper thumbnail of Human Herpesvirus Replication and Abnormal CD8+ T Cell Activation and Low CD4+ T Cell Counts in Antiretroviral-Suppressed HIV-Infected Patients

Research paper thumbnail of Phenotypic, Functional, and Kinetic Parameters Associated with Apparent T-Cell Control of Human Immunodeficiency Virus Replication in Individuals with and without Antiretroviral Treatment

Journal of Virology, 2005

The human immunodeficiency virus (HIV)-mediated immune response may be beneficial or harmful, dep... more The human immunodeficiency virus (HIV)-mediated immune response may be beneficial or harmful, depending on the balance between expansion of HIV-specific T cells and the level of generalized immune activation. The current study utilizes multicolor cytokine flow cytometry to study HIV-specific T cells and T-cell activation in 179 chronically infected individuals at various stages of HIV disease, including those with low-level viremia in the absence of therapy (“controllers”), low-level drug-resistant viremia in the presence of therapy (partial controllers on antiretroviral therapy [PCAT]), and high-level viremia (“noncontrollers”). Compared to noncontrollers, controllers exhibited higher frequencies of HIV-specific interleukin-2-positive gamma interferon-positive (IL-2 + IFN-γ + ) CD4 + T cells. The presence of HIV-specific CD4 + IL-2 + T cells was associated with low levels of proliferating T cells within the less-differentiated T-cell subpopulations (defined by CD45RA, CCR7, CD27, a...

Research paper thumbnail of Neutralizing Antibody Responses against Autologous and Heterologous Viruses in Acute versus Chronic Human Immunodeficiency Virus (HIV) Infection: Evidence for a Constraint on the Ability of HIV To Completely Evade Neutralizing Antibody Responses

Journal of Virology, 2006

Acute human immunodeficiency virus (HIV) infection is associated with the rapid development of ne... more Acute human immunodeficiency virus (HIV) infection is associated with the rapid development of neutralization escape mutations. The degree to which viral evolution persists in chronic infection has not been well characterized, nor is it clear if all patients develop high-level neutralization antibody escape. We therefore measured neutralizing antibody responses against autologous and heterologous viruses in a cohort of acutely and chronically infected subjects (n = 65). Neutralizing antibody responses against both autologous virus and heterologous viruses were lower among individuals with acute infection than among those with chronic infection. Among chronically infected individuals, there was a negative correlation between the level of neutralizing antibodies against autologous virus and the level of viremia. In contrast, there was a positive correlation between the level of neutralizing antibodies against a panel of heterologous viruses and the level of viremia. Viral evolution, a...

Research paper thumbnail of HLA Class I-Restricted T-Cell Responses May Contribute to the Control of Human Immunodeficiency Virus Infection, but Such Responses Are Not Always Necessary for Long-Term Virus Control

Journal of Virology, 2008

A rare subset of human immunodeficiency virus (HIV)-infected individuals maintains undetectable H... more A rare subset of human immunodeficiency virus (HIV)-infected individuals maintains undetectable HIV RNA levels without therapy (“elite controllers”). To clarify the role of T-cell responses in mediating virus control, we compared HLA class I polymorphisms and HIV-specific T-cell responses among a large cohort of elite controllers (HIV-RNA < 75 copies/ml), “viremic” controllers (low-level viremia without therapy), “noncontrollers” (high-level viremia), and “ antiretroviral therapy suppressed” individuals (undetectable HIV-RNA levels on antiretroviral therapy). The proportion of CD4 + and CD8 + T cells that produce gamma interferon (IFN-γ) and interleukin-2 (IL-2) in response to Gag and Pol peptides was highest in the elite and viremic controllers ( P < 0.0001). Forty percent of the elite controllers were HLA-B*57 compared to twenty-three percent of viremic controllers and nine percent of noncontrollers ( P < 0.001). Other HLA class I alleles more common in elite controllers ...

Research paper thumbnail of HIV-1 Infection Abrogates CD8+ T Cell Mitogen-Activated Protein Kinase Signaling Responses

Journal of Virology, 2011

Mitogen-activated protein kinase (MAPK) signaling pathways are dynamic and sensitive regulators o... more Mitogen-activated protein kinase (MAPK) signaling pathways are dynamic and sensitive regulators of T cell function and differentiation. Altered MAPK signaling has been associated with the inflammatory and autoimmune diseases lupus and arthritis and with some pathogenic viral infections. HIV-1 infection is characterized by chronic immune inflammation, aberrantly heightened CD8 + T cell activation levels, and altered T cell function. The relationship between MAPK pathway function, HIV-1-induced activation (CD38 and HLA-DR), and exhaustion (Tim-3) markers in circulating CD8 + T cells remains unknown. Phosphorylation of the MAPK effector proteins ERK and p38 was examined by “phosflow” flow cytometry in 79 recently HIV-1-infected, antiretroviral-treatment-naïve adults and 21 risk-matched HIV-1-negative controls. We identified a subset of CD8 + T cells refractory to phorbol 12-myristate 13-acetate plus ionomycin-induced ERK1/2 phosphorylation (referred to as p-ERK1/2-refractory cells) tha...

Research paper thumbnail of Relationship between T Cell Activation and CD4+T Cell Count in HIV‐Seropositive Individuals with Undetectable Plasma HIV RNA Levels in the Absence of Therapy

The Journal of Infectious Diseases, 2008

Background. Although untreated human immunodeficiency virus (HIV)-infected patients maintaining u... more Background. Although untreated human immunodeficiency virus (HIV)-infected patients maintaining undetectable plasma HIV RNA levels (elite controllers) have high HIV-specific immune responses, it is unclear whether they experience abnormal levels of T cell activation, potentially contributing to immunodeficiency. Methods. We compared percentages of activated (CD38 ϩ HLA-DR ϩ) T cells between 30 elite controllers, 47 HIV-uninfected individuals, 187 HIV-infected individuals with undetectable viremia receiving antiretroviral therapy (antiretroviral therapy suppressed), and 66 untreated HIV-infected individuals with detectable viremia. Because mucosal translocation of bacterial products may contribute to T cell activation in HIV infection, we also measured plasma lipopolysaccharide (LPS) levels. Results. Although the median CD4 ϩ cell count in controllers was 727 cells/mm 3 , 3 (10%) had CD4 ϩ cell counts Ͻ350 cells/mm 3 and 2 (7%) had acquired immunodeficiency syndrome. Controllers had higher CD4 ϩ and CD8 ϩ cell activation levels (P Ͻ .001 for both) than HIV-negative subjects and higher CD8 ϩ cell activation levels than the antiretroviral therapy suppressed (P ϭ .048). In controllers, higher CD4 ϩ and CD8 ϩ T cell activation was associated with lower CD4 ϩ cell counts (P ϭ .009 and P ϭ .047). Controllers had higher LPS levels than HIV-negative subjects (P Ͻ .001), and in controllers higher LPS level was associated with higher CD8 ϩ T cell activation (P ϭ .039). Conclusion. HIV controllers have abnormally high T cell activation levels, which may contribute to progressive CD4 ϩ T cell loss even without measurable viremia.

Research paper thumbnail of Raltegravir Treatment Intensification Does Not Alter Cerebrospinal Fluid HIV-1 Infection or Immunoactivation in Subjects on Suppressive Therapy

Journal of Infectious Diseases, 2011

Research paper thumbnail of T Cell Activation and Senescence Predict Subclinical Carotid Artery Disease in HIV-Infected Women

The Journal of Infectious Diseases, 2011

Background. Individuals infected with human immunodeficiency virus (HIV) have increased risk of c... more Background. Individuals infected with human immunodeficiency virus (HIV) have increased risk of cardiovascular events. It is unknown whether T cell activation and senescence, 2 immunologic sequelae of HIV infection, are associated with vascular disease among HIV-infected adults. Methods. T cell phenotyping and carotid ultrasound were assessed among 115 HIV-infected women and 43 age-and race/ethnicity-matched HIV-uninfected controls participating in the Women's Interagency HIV Study. Multivariate analyses were used to assess the association of T cell activation (CD38 1 HLA-DR 1) and senescence (CD28 2 CD57 1) with subclinical carotid artery disease. Results. Compared with HIV-uninfected women, frequencies of CD4 1 CD38 1 HLA-DR 1 , CD8 1 CD38 1 HLA-DR 1 , and CD8 1 CD28 2 CD57 1 T cells were higher among HIV-infected women, including those who achieved viral suppression while receiving antiretroviral treatment. Among HIV-infected women, adjusted for age, antiretroviral medications, and viral load, higher frequencies of activated CD4 1 and CD8 1 T cells and immunosenescent CD8 1 T cells were associated with increased prevalence of carotid artery lesions (prevalence ratio lesions associated with activated CD4 1 T cells, 1.6 per SD [95% confidence interval {CI}, 1.1-2.2]; P 5 .02; prevalence ratio lesions associated with activated CD8 1 T cells, 2.0 per SD [95% CI, 1.2-3.3]; P , .01; prevalence ratio lesions associated with senescent CD8 1 T cells, 1.9 per SD [95% CI, 1.1-3.1]; P 5 .01). Conclusions. HIV-associated T cell changes are associated with subclinical carotid artery abnormalities, which may be observed even among those patients achieving viral suppression with effective antiretroviral therapy.

Research paper thumbnail of Human Immunodeficiency Virus Persistence and Production in T-Cell Development

Clinical and Vaccine Immunology, 2006

Human immunodeficiency virus type 1 (HIV-1) replication depends on CD4 and coreceptor expression ... more Human immunodeficiency virus type 1 (HIV-1) replication depends on CD4 and coreceptor expression as well as host factors associated with the activation state of the cell. To determine the impact of the activation stage of thymocytes on the HIV-1 life cycle, we investigated R5 and X4 HIV-1 entry, reverse transcription, and expression in discrete thymocyte subsets at different stages of T-cell development. Early after infection, preferential entry and replication of R5 HIV-1 were predominantly detected in mature CD3+/hi CD27+ thymocytes. Thus, R5 HIV-1 targets the stage of development where thymocytes acquire functional responsiveness, which has important implications for HIV pathogenesis. In contrast, X4 HIV-1 expression and replication were primarily found in immature CD3−/+/low CD27− CD69− thymocytes. HIV-1 proviral burden and virus expression in thymocyte subsets correlated with the expression of the highest levels of the respective coreceptor. R5 and X4 HIV-1 entered and complete...

Research paper thumbnail of CD4+ T Cells Expressing PD-1, TIGIT and LAG-3 Contribute to HIV Persistence during ART

PLoS pathogens, 2016

HIV persists in a small pool of latently infected cells despite antiretroviral therapy (ART). Ide... more HIV persists in a small pool of latently infected cells despite antiretroviral therapy (ART). Identifying cellular markers expressed at the surface of these cells may lead to novel therapeutic strategies to reduce the size of the HIV reservoir. We hypothesized that CD4+ T cells expressing immune checkpoint molecules would be enriched in HIV-infected cells in individuals receiving suppressive ART. Expression levels of 7 immune checkpoint molecules (PD-1, CTLA-4, LAG-3, TIGIT, TIM-3, CD160 and 2B4) as well as 4 markers of HIV persistence (integrated and total HIV DNA, 2-LTR circles and cell-associated unspliced HIV RNA) were measured in PBMCs from 48 virally suppressed individuals. Using negative binomial regression models, we identified PD-1, TIGIT and LAG-3 as immune checkpoint molecules positively associated with the frequency of CD4+ T cells harboring integrated HIV DNA. The frequency of CD4+ T cells co-expressing PD-1, TIGIT and LAG-3 independently predicted the frequency of cell...

Research paper thumbnail of Effects of Combined CCR5/Integrase Inhibitors-Based Regimen on Mucosal Immunity in HIV-Infected Patients Naïve to Antiretroviral Therapy: A Pilot Randomized Trial

Research paper thumbnail of Site-Specific Differences in T Cell Frequencies and Phenotypes in the Blood and Gut of HIV-Uninfected and ART-Treated HIV+ Adults

PLOS ONE, 2015

Gastrointestinal T lymphocytes are critical for mucosal immunity and HIV pathogenesis, yet little... more Gastrointestinal T lymphocytes are critical for mucosal immunity and HIV pathogenesis, yet little is known about normal T cell numbers and phenotypes in different regions of the gut, or the degree to which ART can restore levels to those of HIV-uninfected individuals. To investigate these questions, we measured T cell frequencies and markers of memory, activation, anergy, and homing in the blood, ileum, and rectum of HIV-and ART-suppressed HIV+ adults. In HIV-individuals, T cell frequencies and phenotypes differed significantly between sites. Compared to HIV-adults, HIV+ adults had lower absolute CD4+T cell counts in the ileal lamina propria and lower relative CD4+T cell counts in the blood and ileum. In the gut, HIV+ adults had a higher proportion of CD38+ CD4+T cells, a lower proportion of terminallydifferentiated effector cells, and, in the rectum, a higher proportion of CTLA-4+ CD4+T cells. In HIV+ individuals, relative CD4+T cell numbers in the ileum correlated with the proportion of CTLA-4+ CD4+T cells, whereas in the rectum, they tended to correlate with the proportion of circulating CD4+T cells expressing α4β7 or CCR6. Mechanisms of T cell reconstitution may differ throughout the gut, with homing contributing more in the rectum while ileal reconstitution is associated with mucosal CD4+T cell anergy.

Research paper thumbnail of Progressive increase in central nervous system immune activation in untreated primary HIV-1 infection

Journal of Neuroinflammation, 2014

Research paper thumbnail of Limited HIV infection of central memory and stem cell memory CD4+ T cells is associated with lack of progression in viremic individuals

PLoS pathogens, 2014

A rare subset of HIV-infected individuals, designated viremic non-progressors (VNP), remain asymp... more A rare subset of HIV-infected individuals, designated viremic non-progressors (VNP), remain asymptomatic and maintain normal levels of CD4+ T-cells despite persistently high viremia. To identify mechanisms potentially responsible for the VNP phenotype, we compared VNPs (average >9 years of HIV infection) to HIV-infected individuals who have similar CD4+ T-cell counts and viral load, but who are likely to progress if left untreated ("putative…

Research paper thumbnail of Expression profile of host restriction factors in HIV-1 elite controllers

Retrovirology, Jan 16, 2013

Several host-encoded antiviral factors suppress HIV-1 replication in a cell-autonomous fashion in... more Several host-encoded antiviral factors suppress HIV-1 replication in a cell-autonomous fashion in vitro. The relevance of these defenses to the control of HIV-1 in vivo remains to be elucidated. We hypothesized that cellular restriction of HIV-1 replication plays a significant role in the observed suppression of HIV-1 in "elite controllers", individuals who maintain undetectable levels of viremia in the absence of antiretroviral therapy (ART). We comprehensively compared the expression levels of 34 host restriction factors and cellular activation levels in CD4+ T cells and sorted T cell subsets between elite controllers, HIV-1-infected (untreated) non-controllers, ART-suppressed, and uninfected individuals. Expression of schlafen 11, a codon usage-based inhibitor of HIV-1 protein synthesis, was significantly elevated in CD4+ T cells from elite controllers as compared to both non-controllers (p = 0.048) and ART-suppressed individuals (p = 0.024), with this effect most appar...

Research paper thumbnail of HIV-Infected Individuals with Low CD4/CD8 Ratio despite Effective Antiretroviral Therapy Exhibit Altered T Cell Subsets, Heightened CD8+ T Cell Activation, and Increased Risk of Non-AIDS Morbidity and Mortality

PLoS Pathogens, 2014

A low CD4/CD8 ratio in elderly HIV-uninfected adults is associated with increased morbidity and m... more A low CD4/CD8 ratio in elderly HIV-uninfected adults is associated with increased morbidity and mortality. A subset of HIVinfected adults receiving effective antiretroviral therapy (ART) fails to normalize this ratio, even after they achieve normal CD4+ T cell counts. The immunologic and clinical characteristics of this clinical phenotype remain undefined. Using data from four distinct clinical cohorts and three clinical trials, we show that a low CD4/CD8 ratio in HIV-infected adults during otherwise effective ART (after CD4 count recovery above 500 cells/mm 3) is associated with a number of immunological abnormalities, including a skewed T cell phenotype from naïve toward terminally differentiated CD8+ T cells, higher levels of CD8+ T cell activation (HLADR+CD38+) and senescence (CD282 and CD57+CD282), and higher kynurenine/tryptophan ratio. Changes in the peripheral CD4/CD8 ratio are also reflective of changes in gut mucosa, but not in lymph nodes. In a longitudinal study, individuals who initiated ART within six months of infection had greater CD4/CD8 ratio increase compared to later initiators (.2 years). After controlling for age, gender, ART duration, nadir and CD4 count, the CD4/CD8 ratio predicted increased risk of morbidity and mortality. Hence, a persistently low CD4/CD8 ratio during otherwise effective ART is associated with increased innate and adaptive immune activation, an immunosenescent phenotype, and higher risk of morbidity/mortality. This ratio may prove useful in monitoring response to ART and could identify a unique subset of individuals needed of novel therapeutic interventions.

Research paper thumbnail of Prospective Antiretroviral Treatment of Asymptomatic, HIV-1 Infected Controllers

PLoS Pathogens, 2013

The study of HIV-infected ''controllers'' who are able to maintain low levels of plasma HIV RNA i... more The study of HIV-infected ''controllers'' who are able to maintain low levels of plasma HIV RNA in the absence of antiretroviral therapy (ART) may provide insights for HIV cure and vaccine strategies. Despite maintaining very low levels of plasma viremia, controllers have elevated immune activation and accelerated atherosclerosis. However, the degree to which low-level replication contributes to these phenomena is not known. Sixteen asymptomatic controllers were prospectively treated with ART for 24 weeks. Controllers had a statistically significant decrease in ultrasensitive plasma and rectal HIV RNA levels with ART. Markers of T cell activation/dysfunction in blood and gut mucosa also decreased substantially with ART. Similar reductions were observed in the subset of ''elite'' controllers with pre-ART plasma HIV RNA levels below conventional assays (,40 copies/mL). These data confirm that HIV replication persists in controllers and contributes to a chronic inflammatory state. ART should be considered for these individuals (ClinicalTrials.gov NCT01025427).

Research paper thumbnail of Challenges in Detecting HIV Persistence during Potentially Curative Interventions: A Study of the Berlin Patient

PLoS Pathogens, 2013

There is intense interest in developing curative interventions for HIV. How such a cure will be q... more There is intense interest in developing curative interventions for HIV. How such a cure will be quantified and defined is not known. We applied a series of measurements of HIV persistence to the study of an HIV-infected adult who has exhibited evidence of cure after allogeneic hematopoietic stem cell transplant from a homozygous CCR5D32 donor. Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV DNA or RNA was detected in peripheral blood mononuclear cells (PBMC), spinal fluid, lymph node, or terminal ileum, and no replication-competent virus could be cultured from PBMCs. However, HIV RNA was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in ART-suppressed patients. It was not possible to obtain sequence data from plasma or gut, while an X4 sequence from PBMC did not match the pre-transplant sequence. HIV antibody levels were readily detectable but declined over time; T cell responses were largely absent. The occasional, low-level PCR signals raise the possibility that some HIV nucleic acid might persist, although they could also be false positives. Since HIV levels in well-treated individuals are near the limits of detection of current assays, more sensitive assays need to be developed and validated. The absence of recrudescent HIV replication and waning HIV-specific immune responses five years after withdrawal of treatment provide proof of a clinical cure.

Research paper thumbnail of A Low T Regulatory Cell Response May Contribute to Both Viral Control and Generalized Immune Activation in HIV Controllers

Research paper thumbnail of Cytomegalovirus-Specific T Cells Persist at Very High Levels during Long-Term Antiretroviral Treatment of HIV Disease

PLoS ONE, 2010

Background: In healthy, HIV seronegative, CMV seropositive adults, a large proportion of T cells ... more Background: In healthy, HIV seronegative, CMV seropositive adults, a large proportion of T cells are CMV-specific. High-level CMV-specific T cell responses are associated with accelerated immunologic aging (''immunosenesence'') in the elderly population. The impact of untreated and treated HIV infection on the frequency of these cells remains undefined. Methodology/Principal Findings: We measured the proportion of CD4+ and CD8+ T cells responding to CMV pp65 and IE proteins was measured using flow cytometry in 685 unique HIV seronegative and seropositive individuals. The proportion of CMV-specific CD8+ T cells was consistently higher in the HIV-seropositive subjects compared to the HIV-seronegative subjects. This HIV effect was observed even in patients who lacked measurable immunodeficiency. Among the HIVseropositive subjects, CMV-specific CD8+ T cell responses were proportionately lower during recent infection, higher during chronic untreated infection and higher still during long-term antiretroviral treated infection. The CD8+ T cell response to just two CMV proteins (pp65 and IE) was approximately 6% during long-term therapy, which was over twice that seen in HIV-seronegative persons. CMV-specific CD4+ T cell responses followed the same trends, but the magnitude of the effect was smaller. Conclusions/Significance: Long-term successfully treated HIV infected patients have remarkably high levels of CMV-specific effector cells. These levels are similar to that observed in the elderly, but occur at much younger ages. Future studies should focus on defining the potential role of the CMV-specific inflammatory response in non-AIDS morbidity and mortality, including immunosenescence.

Research paper thumbnail of Human Herpesvirus Replication and Abnormal CD8+ T Cell Activation and Low CD4+ T Cell Counts in Antiretroviral-Suppressed HIV-Infected Patients

Research paper thumbnail of Phenotypic, Functional, and Kinetic Parameters Associated with Apparent T-Cell Control of Human Immunodeficiency Virus Replication in Individuals with and without Antiretroviral Treatment

Journal of Virology, 2005

The human immunodeficiency virus (HIV)-mediated immune response may be beneficial or harmful, dep... more The human immunodeficiency virus (HIV)-mediated immune response may be beneficial or harmful, depending on the balance between expansion of HIV-specific T cells and the level of generalized immune activation. The current study utilizes multicolor cytokine flow cytometry to study HIV-specific T cells and T-cell activation in 179 chronically infected individuals at various stages of HIV disease, including those with low-level viremia in the absence of therapy (“controllers”), low-level drug-resistant viremia in the presence of therapy (partial controllers on antiretroviral therapy [PCAT]), and high-level viremia (“noncontrollers”). Compared to noncontrollers, controllers exhibited higher frequencies of HIV-specific interleukin-2-positive gamma interferon-positive (IL-2 + IFN-γ + ) CD4 + T cells. The presence of HIV-specific CD4 + IL-2 + T cells was associated with low levels of proliferating T cells within the less-differentiated T-cell subpopulations (defined by CD45RA, CCR7, CD27, a...

Research paper thumbnail of Neutralizing Antibody Responses against Autologous and Heterologous Viruses in Acute versus Chronic Human Immunodeficiency Virus (HIV) Infection: Evidence for a Constraint on the Ability of HIV To Completely Evade Neutralizing Antibody Responses

Journal of Virology, 2006

Acute human immunodeficiency virus (HIV) infection is associated with the rapid development of ne... more Acute human immunodeficiency virus (HIV) infection is associated with the rapid development of neutralization escape mutations. The degree to which viral evolution persists in chronic infection has not been well characterized, nor is it clear if all patients develop high-level neutralization antibody escape. We therefore measured neutralizing antibody responses against autologous and heterologous viruses in a cohort of acutely and chronically infected subjects (n = 65). Neutralizing antibody responses against both autologous virus and heterologous viruses were lower among individuals with acute infection than among those with chronic infection. Among chronically infected individuals, there was a negative correlation between the level of neutralizing antibodies against autologous virus and the level of viremia. In contrast, there was a positive correlation between the level of neutralizing antibodies against a panel of heterologous viruses and the level of viremia. Viral evolution, a...

Research paper thumbnail of HLA Class I-Restricted T-Cell Responses May Contribute to the Control of Human Immunodeficiency Virus Infection, but Such Responses Are Not Always Necessary for Long-Term Virus Control

Journal of Virology, 2008

A rare subset of human immunodeficiency virus (HIV)-infected individuals maintains undetectable H... more A rare subset of human immunodeficiency virus (HIV)-infected individuals maintains undetectable HIV RNA levels without therapy (“elite controllers”). To clarify the role of T-cell responses in mediating virus control, we compared HLA class I polymorphisms and HIV-specific T-cell responses among a large cohort of elite controllers (HIV-RNA < 75 copies/ml), “viremic” controllers (low-level viremia without therapy), “noncontrollers” (high-level viremia), and “ antiretroviral therapy suppressed” individuals (undetectable HIV-RNA levels on antiretroviral therapy). The proportion of CD4 + and CD8 + T cells that produce gamma interferon (IFN-γ) and interleukin-2 (IL-2) in response to Gag and Pol peptides was highest in the elite and viremic controllers ( P < 0.0001). Forty percent of the elite controllers were HLA-B*57 compared to twenty-three percent of viremic controllers and nine percent of noncontrollers ( P < 0.001). Other HLA class I alleles more common in elite controllers ...

Research paper thumbnail of HIV-1 Infection Abrogates CD8+ T Cell Mitogen-Activated Protein Kinase Signaling Responses

Journal of Virology, 2011

Mitogen-activated protein kinase (MAPK) signaling pathways are dynamic and sensitive regulators o... more Mitogen-activated protein kinase (MAPK) signaling pathways are dynamic and sensitive regulators of T cell function and differentiation. Altered MAPK signaling has been associated with the inflammatory and autoimmune diseases lupus and arthritis and with some pathogenic viral infections. HIV-1 infection is characterized by chronic immune inflammation, aberrantly heightened CD8 + T cell activation levels, and altered T cell function. The relationship between MAPK pathway function, HIV-1-induced activation (CD38 and HLA-DR), and exhaustion (Tim-3) markers in circulating CD8 + T cells remains unknown. Phosphorylation of the MAPK effector proteins ERK and p38 was examined by “phosflow” flow cytometry in 79 recently HIV-1-infected, antiretroviral-treatment-naïve adults and 21 risk-matched HIV-1-negative controls. We identified a subset of CD8 + T cells refractory to phorbol 12-myristate 13-acetate plus ionomycin-induced ERK1/2 phosphorylation (referred to as p-ERK1/2-refractory cells) tha...

Research paper thumbnail of Relationship between T Cell Activation and CD4+T Cell Count in HIV‐Seropositive Individuals with Undetectable Plasma HIV RNA Levels in the Absence of Therapy

The Journal of Infectious Diseases, 2008

Background. Although untreated human immunodeficiency virus (HIV)-infected patients maintaining u... more Background. Although untreated human immunodeficiency virus (HIV)-infected patients maintaining undetectable plasma HIV RNA levels (elite controllers) have high HIV-specific immune responses, it is unclear whether they experience abnormal levels of T cell activation, potentially contributing to immunodeficiency. Methods. We compared percentages of activated (CD38 ϩ HLA-DR ϩ) T cells between 30 elite controllers, 47 HIV-uninfected individuals, 187 HIV-infected individuals with undetectable viremia receiving antiretroviral therapy (antiretroviral therapy suppressed), and 66 untreated HIV-infected individuals with detectable viremia. Because mucosal translocation of bacterial products may contribute to T cell activation in HIV infection, we also measured plasma lipopolysaccharide (LPS) levels. Results. Although the median CD4 ϩ cell count in controllers was 727 cells/mm 3 , 3 (10%) had CD4 ϩ cell counts Ͻ350 cells/mm 3 and 2 (7%) had acquired immunodeficiency syndrome. Controllers had higher CD4 ϩ and CD8 ϩ cell activation levels (P Ͻ .001 for both) than HIV-negative subjects and higher CD8 ϩ cell activation levels than the antiretroviral therapy suppressed (P ϭ .048). In controllers, higher CD4 ϩ and CD8 ϩ T cell activation was associated with lower CD4 ϩ cell counts (P ϭ .009 and P ϭ .047). Controllers had higher LPS levels than HIV-negative subjects (P Ͻ .001), and in controllers higher LPS level was associated with higher CD8 ϩ T cell activation (P ϭ .039). Conclusion. HIV controllers have abnormally high T cell activation levels, which may contribute to progressive CD4 ϩ T cell loss even without measurable viremia.

Research paper thumbnail of Raltegravir Treatment Intensification Does Not Alter Cerebrospinal Fluid HIV-1 Infection or Immunoactivation in Subjects on Suppressive Therapy

Journal of Infectious Diseases, 2011

Research paper thumbnail of T Cell Activation and Senescence Predict Subclinical Carotid Artery Disease in HIV-Infected Women

The Journal of Infectious Diseases, 2011

Background. Individuals infected with human immunodeficiency virus (HIV) have increased risk of c... more Background. Individuals infected with human immunodeficiency virus (HIV) have increased risk of cardiovascular events. It is unknown whether T cell activation and senescence, 2 immunologic sequelae of HIV infection, are associated with vascular disease among HIV-infected adults. Methods. T cell phenotyping and carotid ultrasound were assessed among 115 HIV-infected women and 43 age-and race/ethnicity-matched HIV-uninfected controls participating in the Women's Interagency HIV Study. Multivariate analyses were used to assess the association of T cell activation (CD38 1 HLA-DR 1) and senescence (CD28 2 CD57 1) with subclinical carotid artery disease. Results. Compared with HIV-uninfected women, frequencies of CD4 1 CD38 1 HLA-DR 1 , CD8 1 CD38 1 HLA-DR 1 , and CD8 1 CD28 2 CD57 1 T cells were higher among HIV-infected women, including those who achieved viral suppression while receiving antiretroviral treatment. Among HIV-infected women, adjusted for age, antiretroviral medications, and viral load, higher frequencies of activated CD4 1 and CD8 1 T cells and immunosenescent CD8 1 T cells were associated with increased prevalence of carotid artery lesions (prevalence ratio lesions associated with activated CD4 1 T cells, 1.6 per SD [95% confidence interval {CI}, 1.1-2.2]; P 5 .02; prevalence ratio lesions associated with activated CD8 1 T cells, 2.0 per SD [95% CI, 1.2-3.3]; P , .01; prevalence ratio lesions associated with senescent CD8 1 T cells, 1.9 per SD [95% CI, 1.1-3.1]; P 5 .01). Conclusions. HIV-associated T cell changes are associated with subclinical carotid artery abnormalities, which may be observed even among those patients achieving viral suppression with effective antiretroviral therapy.