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Augmentation of HIV-specific T cell function by immediate treatment of hyperacute HIV-1 infection
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Sustained viremia after acute HIV infection is associated with profound CD4+ T cell loss and exhaustion of HIV-specific CD8+ T cell responses. After transmission, there is considerable heterogeneity in the rate of disease progression, which is affected by the magnitude of the set point viral load and the initial CD4+ T cell loss (3–5). Therefore, investigating factors that influence the quality of antiviral immune responses during the earliest stages of HIV infection may reveal specific responses that affect the clinical course of disease and inform vaccine development. In this study, we conducted a detailed analysis of immune responses generated when cART is initiated in Fiebig stages I and II infection, before peak viremia, compared to treatment initiation at Fiebig stage III and later.
In this study, we observed several CD4+ T cell functional abnormalities in UnTx persons that were not apparent in early Tx donors. Consistent with previous reports (37), UnTx HIV infection was associated with a paucity of HIV-specific CD4+ T cell responses. In addition, we observed diminished responses to HIV antigens and mitogens signifying HIV-induced generalized CD4+ T cell functional impairment. In contrast, robust CD4+ T cell proliferative responses were induced in early Tx donors and were maintained with prolonged cART-mediated viral suppression. Together, these results highlight the ability of CD4+ T cell helper function to enhance CD8+ T cell responses and underscore the need for more mechanistic work focused on defining the nature of CD4+ T cell help to CD8+ T cells.
There is compelling evidence that early diagnosis and treatment of HIV infection have the benefits of reducing the HIV reservoir size and decreasing transmission of the virus to sexual partners (52). However, the impact of extremely early cART on induction of adaptive cellular immune responses with the potential to suppress HIV infection was unknown. In this study, we showed that treatment initiated during hyperacute infection induces HIV-specific CD4+ and CD8+ T cell responses that differ in magnitude, phenotype, and function from responses generated in people who delay treatment. We show that preservation of CD4+ T cells by early cART initiation may have a critical role in shaping CD8+ T cell function. We also identified key molecules that could be potential targets for manipulation to restore CD8+ T cell function, such as BCL-2 and CD127. Overall, our results show that early cART leads to persistent functional T cell responses that are generated in most individuals with hyperacute infection. These data open up the possibility of harnessing immune responses generated under early treatment as a first critical step in the path toward immune-mediated HIV cure or remission strategies.
We can manipulate the immune system to reverse comorbidities - HIV related immune dysfunction that causes comorbidities. Jules Levin
Zaza M. Ndhlovu1,2,3,4*, Samuel W. Kazer2,5,6,7, Thandeka Nkosi1,4, Funsho Ogunshola1,4, Daniel M. Muema1, Gursev Anmole8, Shayda A. Swann9, Amber Moodley4, Krista Dong2, Tarylee Reddy10, Mark A. Brockman8,9, Alex K. Shalek2,5,6,7, Thumbi Ndung'u1,4, Bruce D. Walker2,3,4,5,7*
Our findings have implications for the HIV vaccine and cure research and provide insights into the relationship between acute antigen exposure and T cell functionality.
There is compelling evidence that early diagnosis and treatment of HIV infection have the benefits of reducing the HIV reservoir size and decreasing transmission of the virus to sexual partners (52). However, the impact of extremely early cART on induction of adaptive cellular immune responses with the potential to suppress HIV infection was unknown. In this study, we showed that treatment initiated during hyperacute infection induces HIV-specific CD4+ and CD8+ T cell responses that differ in magnitude, phenotype, and function from responses generated in people who delay treatment. We show that preservation of CD4+ T cells by early cART initiation may have a critical role in shaping CD8+ T cell function. We also identified key molecules that could be potential targets for manipulation to restore CD8+ T cell function, such as BCL-2 and CD127. Overall, our results show that early cART leads to persistent functional T cell responses that are generated in most individuals with hyperacute infection. These data open up the possibility of harnessing immune responses generated under early treatment as a first critical step in the path toward immune-mediated HIV cure or remission strategies.
Science Translational Medicine 22 May 2019
Keeping it FRESH in HIV
HIV infection affects the immune system beyond infected CD4+ T cells and can cause systemic immune dysfunctions even when the virus is controlled by antiretroviral treatment. To determine how early treatment affects anti-HIV T cell responses, Ndhlovu et al. examined samples from the FRESH cohort, which enables analysis of hyperacute infection. They compared HIV-specific CD8+ T cells from women who initiated treatment within 2 days of HIV diagnosis to those that started treatment during the acute or chronic phase of infection. CD8+ T cells from individuals that started treatment immediately had preserved functionality, likely due to limited viremia. The antiviral capacity of these cells may be a useful goal for HIV vaccine design.
Abstract
Sustained viremia after acute HIV infection is associated with profound CD4+ T cell loss and exhaustion of HIV-specific CD8+ T cell responses. To determine the impact of combination antiretroviral therapy (cART) on these processes, we examined the evolution of immune responses in acutely infected individuals initiating treatment before peak viremia. Immediate treatment of Fiebig stages I and II infection led to a rapid decline in viral load and diminished magnitude of HIV-specific (tetramer+) CD8+ T cell responses compared to untreated donors. There was a strong positive correlation between cumulative viral antigen exposure before full cART-induced suppression and immune responses measured by MHC class I tetramers, IFN-γ ELISPOT, and CD8+ T cell activation. HIV-specific CD8+ T responses of early treated individuals were characterized by increased CD127 and BCL-2 expression, greater in vitro IFN-γ secretion, and enhanced differentiation into effector memory (Tem) cells. Transcriptional analysis of tetramer+ CD8+ T cells from treated persons revealed reduced expression of genes associated with activation and apoptosis, with concurrent up-regulation of prosurvival genes including BCL-2, AXL, and SRC. Early treatment also resulted in robust HIV-specific CD4+ T cell responses compared to untreated HIV-infected individuals. Our data show that limiting acute viremia results in enhanced functionality of HIV-specific CD4+ and CD8+ T cells, preserving key antiviral properties of these cells.
INTRODUCTION
Despite considerable prevention efforts, continuing global HIV transmissions result in increasing numbers of lifelong infections; moreover, substantial scientific challenges remain in the quest for an effective vaccine or cure (1, 2). After transmission, there is considerable heterogeneity in the rate of disease progression, which is affected by the magnitude of the set point viral load and the initial CD4+ T cell loss (3–5). Therefore, investigating factors that influence the quality of antiviral immune responses during the earliest stages of HIV infection may reveal specific responses that affect the clinical course of disease and inform vaccine development.
The emergence of HIV-specific CD8+ T cell responses has consistently been associated with reduction in peak virus replication during primary infection (6–10). Rapid escape from HIV-specific CD8+ T cell responses has been observed in acute infection, indicating antiviral function for at least a subset of these cells (11, 12). By twice-weekly screening of uninfected women at high risk of HIV infection in South Africa from the Females Rising Through Education Support and Health (FRESH) cohort (13, 14), we identified persons with hyperacute infection (defined as the period from onset of plasma viremia to peak viral load) and previously showed that untreated (UnTx) infection is associated with massive HIV-specific CD8+ T cell activation and that the magnitude and kinetics of the initial response affect set-point viral load (8); similar results have been reported in UnTx cohorts in Thailand and East Africa (15, 16). These studies identified defects in early responses that could contribute to lack of complete viral suppression, including increased T cell apoptosis and the inability to up-regulate prosurvival molecules, such as CD127 required for establishment of long-term immunologic memory (8). However, how these defects relate to overall antigen exposure and whether such defects could be abrogated by limiting antigen exposure in the earliest stages of infection remain unknown.
In contrast to UnTx acute infection, combination antiretroviral therapy (cART) initiation during and after peak viremia in primary HIV infection is associated with improved T cell functionality and reduction in the size of the viral reservoir and, in some cases, has been associated with prolonged remission after treatment discontinuation (17–20), suggesting that very early cART treatment in infection has a positive effect on antiviral immune responses. Moreover, numerous studies have shown that early therapy augments HIV-specific CD4+ T cell responses [reviewed in (21)]. More recent studies demonstrate that initiation of cART before peak viremia limits antigen exposure and results in maintenance of CD4+ T cell numbers (13, 22), but abrogates antibody responses and can result in nonreactive HIV serology (13, 23). However, the impact of immediate cART on the induction, evolution, and function of HIV-specific CD4+ and CD8+ T cells has not been fully elucidated.
In this study, we conducted a detailed analysis of immune responses generated when cART is initiated in Fiebig stages I and II infection, before peak viremia, compared to treatment initiation at Fiebig stage III and later. Our findings have implications for the HIV vaccine and cure research and provide insights into the relationship between acute antigen exposure and T cell functionality.
DISCUSSION
UnTx hyperacute HIV infection leads to robust induction of virus-specific CD8+ T cell responses, but these cells rapidly become poorly functional. Here, we conducted an analysis of the impact of treatment initiated before peak viremia on HIV-specific CD8+ T cell responses. This approach enabled us to examine the host response to HIV while limiting concurrent immune destruction, which typifies UnTx acute and chronic infection. These findings provide insight into features associated with natural priming of the immune system by HIV infection in the absence of CD4+ T cell depletion. These studies are relevant to vaccine design because the phenotypes in early Tx donors such as improved CD8 effector function, robust CD4 proliferative responses and maintenance of long-lived T cell memory responses are key antiviral functions, which are desirable to induce with a vaccine.
Several studies of early treatment of HIV infection have examined the effect of treatment initiation after peak viremia (17, 40, 41). Because of the design of the FRESH cohort, we were able to identify infection during Fiebig stages I and II and initiate therapy within 1 to 2 days of detectable viremia in some cases, with peak viremia less than 1000 RNA copies/ml. Despite this limited exposure to detectable viremia, which has been shown to diminish HIV-specific B cell responses (13, 23), most of the individuals developed detectable HIV-specific CD8+ T cell responses. However, the overall magnitude of responses was dependent on the relative exposure to virus, as measured by VCD analogous to viremia copy-years described in chronic HIV infection (42), and was shown to correlate with magnitude and breadth of HIV-specific CD8+ T cell responses. This suggests that the degree of HIV antigen burden is a key driver of acute phase cytotoxic T lymphocyte responses. Whether some of the early Tx individuals lacked HIV-specific CD8+ T cell responses altogether (43), or whether they were not cross-reactive with the reference strain of virus used, or simply below the limits of detection as shown previously in elite controllers (44), is not clear.
Recent studies have highlighted the role of metabolic state in shaping immune cell differentiation and function (45, 46). Through whole-genome RNA-seq analysis, we show that during UnTx acute HIV infection, HIV-specific CD8+ T cells are metabolically hyperactive, functionally impaired, and have a skewed maturation phenotype. Early cART comparatively diminished these immune dysfunctions by relative coordinated down-regulation of the stress response genes, with a concurrent up-regulation of antiapoptotic and prosurvival genes, which are intricately involved in shaping the overall long-term survival of immune responses (31). Few transcriptional differences were found in bystander and CMV-specific CD8+ T cells, highlighting the direct effect of treatment on only those cells targeting HIV-infected cells. This study shows that the key benefit of initiating cART very early is the generation of transcriptionally quiescent immune responses. It is plausible that the less stressed state of the responses in early Tx people could provide better immune priming amenable to rapid boosting with therapeutic vaccines. Moreover, our data provide insights to focus mechanistic studies into the biology of immune responses in early Tx people and identify key molecular targets such as the BCL-2, AXL, and SRC genes and cellular pathways that could be manipulated to enhance the generation of long-lived immune responses by future therapeutic interventions.
Furthermore, we observed divergent differentiation states of HIV-specific CD8+ T cell responses both at the peak of the response and in the chronic phase of infection, an intermediate Ttm population dominated UnTx responses at both the peak and chronic time points. These data suggest that the skewing of the response to this intermediate phenotype happens very early in infection and remains stable over time. In contrast, responses in Tx Fiebig stages I and II individuals were heavily skewed toward the Tem phenotype, classically superior at responding to immune stimuli (47). Sustained viral suppression in early Tx participants converted the responses to Tcm phenotype. These data further support the notion that it will be easier to boost preexisting Tcm responses with a therapeutic vaccine in early Tx individuals due to the inherent ability of Tcm to rapidly expand and acquire effector functions upon restimulation (33).
Last, we investigated whether loss of CD4+ T cells contributed to the observed differences in CD8+ T cell function and phenotype. UnTx HIV infection results in massive depletion of CD4+ T cells, whereas early treatment preserves this population (13, 48, 49). In this study, we observed several CD4+ T cell functional abnormalities in UnTx persons that were not apparent in early Tx donors. Consistent with previous reports (37), UnTx HIV infection was associated with a paucity of HIV-specific CD4+ T cell responses. In addition, we observed diminished responses to HIV antigens and mitogens signifying HIV-induced generalized CD4+ T cell functional impairment. In contrast, robust CD4+ T cell proliferative responses were induced in early Tx donors and were maintained with prolonged cART-mediated viral suppression. Together, these results highlight the ability of CD4+ T cell helper function to enhance CD8+ T cell responses and underscore the need for more mechanistic work focused on defining the nature of CD4+ T cell help to CD8+ T cells.
Notable limitations of the study include variability in the number of days between diagnosis and sample collection, which was due to sample availability constraints. However, difference in number of days between diagnosis and sample collection did not substantially affect the immune parameters measured in the early Tx groups. Second, tetramer analysis was not performed for some of study participants due to a lack of appropriate tetramers. Nonetheless, the wide range of tetramers used in this study covered most of the immunodominant responses in our cohort. Third, despite the differences in the phenotypic composition of memory responses between experimental groups later in infection, RNA-seq only revealed significant differences at the 2-week time point, which is around the peak of activation in UnTx samples. The cells at later time points where more quiescent, which makes it difficult to detect transcriptional differences without previous ex vivo stimulation. Increasing sample size, read depth, and introducing ex vivo stimulation might overcome this limitation. Last, we have not investigated the impact of viral sequence diversity, which may affect antigen exposure in an epitope-specific manner that is not captured by VCD measurements. Early treatment will prevent viral evolution, but escape mutations have been observed in conjunction with the development of CD8+ T cell responses during the first weeks of infection (50, 51). Therefore, additional analyses will be necessary to fully assess the contribution of viral sequence adaptation to differences in TCR clonotype frequencies and transcriptional profiles, particularly for UnTx individuals at later time points.
There is compelling evidence that early diagnosis and treatment of HIV infection have the benefits of reducing the HIV reservoir size and decreasing transmission of the virus to sexual partners (52). However, the impact of extremely early cART on induction of adaptive cellular immune responses with the potential to suppress HIV infection was unknown. In this study, we showed that treatment initiated during hyperacute infection induces HIV-specific CD4+ and CD8+ T cell responses that differ in magnitude, phenotype, and function from responses generated in people who delay treatment. We show that preservation of CD4+ T cells by early cART initiation may have a critical role in shaping CD8+ T cell function. We also identified key molecules that could be potential targets for manipulation to restore CD8+ T cell function, such as BCL-2 and CD127. Overall, our results show that early cART leads to persistent functional T cell responses that are generated in most individuals with hyperacute infection. These data open up the possibility of harnessing immune responses generated under early treatment as a first critical step in the path toward immune-mediated HIV cure or remission strategies.
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Immunosenescent CD4 T cells (CD57+) showed no significant changes in the PHI group as compared to HIV-uninfected individuals but they were significantly increased in the CHI-ART group (P = 0.0001, Figure S3C in Supplementary Material). Exhausted CD8 T cells also showed a transient but less marked significant increase as compared to HIV-uninfected individuals (P < 0.0001, Figure 4C), with a significant and slow decrease over time (P = 0.0056, Figure 4D). Along the course of HIV infection, the frequency of senescent CD8 T-cells was significantly higher in the CHI-ART group as compared to the HIV-uninfected group (P < 0.0001, Figure 4E). However, no significant changes over time were observed in the frequency of senescent CD8 T-cells by linear regression models (Figure 4f). There were no significant differences in percentages of activated, exhausted or senescent CD8 T-cells associated with the presence of co-infection in any of the study ......despite these profound alterations, no relevant increases of the expression of CD57 were observed in CD8 T cells during PHI, suggesting that this marker of replicative immunosenescence could be associated with longstanding HIV infection, suggested by its highest expression in CHI individuals. Moreover, increased CD57 expression in CD8 T-cells was previously reported to be associated with age (47) and ART initiation (48).groups.4F).https://www.frontiersin.org/articles/10.3389/fimmu.2017.01925/full
Aging and CMV both increase the proportion of CD28-CD8+ T cells expressing CD57 [2], [15], and higher percent CD28-CD57+ CD8+ T cells predict mortality in the HIV-uninfected elderly population [11]. Many have hypothesized that the chronic inflammatory state of HIV infection would cause similar CD8+ T cell phenotypic defects [16], [17]. Although HIV infection leads to an expansion of CD28- CD8+ T cells similar to that observed with CMV and aging, HIV results in an abnormally low proportion of these cells that express CD57. This phenomenon may be the reason why prior studies failed to observe decreases in percent CD28-CD57+ CD8+ T cells during ART [18], [19], since the percent CD28- CD8+ T cells declines while the proportion of these cells expressing CD57 increases during treatment. Indeed, the clinical relevance of the percent CD28-CD57+ CD8+ T cells is unclear in HIV infection. While a single study suggested that higher percent CD28-CD57+ CD8+ T cells were associated with greater atherosclerosis in HIV-infected women, it was unclear whether this association was independent of CD8+ T cell activation (or innate immune activation) [9]. The only two studies to date that have assessed the association between the percent CD28-CD57+ CD8+ T cells and mortality in treated HIV infection have tended to show decreased mortality in ART-suppressed individuals with higher frequencies of these cells [20], [21]. This raises the possibility that a decreased proportion of CD28-CD8+ T cells expressing CD57 in HIV-infected individuals might actually predict increased morbidity and mortality, a question we are addressing in a separate study [22]. In summary, we found that the persistent phenotypic CD8+ T cell defects of treated HIV infection are distinct from those observed with CMV infection or aging-associated immunosenescence. While HIV leads to an expansion of CD28- CD8+ T cells, fewer of these cells may be able to successfully complete T cell maturation and proliferation, leading to an overall decrease in the proportion of these cells that express CD57. By examining the proportion of CD28- CD8+ T cells that express CD57 (rather than the proportion of the entire CD8+ T cell population expressing CD57 as has been assessed in prior studies [3], [4], [9]), our study provides insights into a unique CD8+ T abnormality that appears to be different from aging-associated immunosenescence. Future studies will need to clarify the prognostic importance of these abnormalities on clinical outcomes as well as the impact of these abnormalities on CD8+ T cell function in HIV-infected individuals.https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0089444
Higher CD4+ and CD8+ T-cell activation were significantly associated with the presence of at least three comorbidities (respectively, P = 0.0004, P = 0.0001). Higher percentage of senescent and terminally differentiated T cells, and lower percentage of naïve T cells were also significantly correlated with a high comorbidity score (Supplementary Material Table 3, http://links.lww.com/QAD/A751)."......These data suggest that HIV-associated T-cell activation and senescence are involved in comorbidities in suppressed HIV recipients and points to immune activation being involved in comorbidities independently of a unique cardiovascular pathway......Activation and senescence markers were inversely associated with naive markers. It led us to identify two patterns of patients: a cluster of patients characterized by high expression of activation and senescence markers and low levels of naive T cells, and a cluster of patients exhibiting high levels of naive T cells and low expression of activation and senescence markers.
frailty was associated among HIV-infected men with higher interleukin 6 and high-sensitivity C-reactive protein and lower free testosterone and dehydroepiandrosterone levels. In contrast, HIV infection but not frailty was associated with significantly greater immune senescence (percentage of CD4+CD28− or CD8+CD28− T cells) and immune activation (percentages of CD4+CD38+HLA-DR+ and CD8+CD38+HLA-DR+ T cells). Whether treatments to replace or normalize these hormones might result in improvement in HIV-infected adults remains to be clearly established in either HIV-infected or HIV-uninfected populations.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897840/
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. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4022662/
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