Plasmacytoid dendritic cell and functional HIV Gag p55-specific T cells before treatment interruption can inform set-point plasma HIV viral load after treatment interruption in chronically suppressed HIV-1(+) patients

Comparable HIV suppression by pegylated-IFN-α2a or pegylated-IFN-α2b during a 4-week analytical treatment interruption

We report on the post-hoc analysis of three clinical studies (NCT01935089, NCT00594880 and NCT00051818) with chronically HIV-infected, immune-reconstituted individuals with similar entry criteria, and demographics interrupting antiretroviral therapy (ART) without or with 5 weeks of weekly pegylated (Peg)-IFN-α2b or Peg-IFN-α2a immunotherapy added onto ART. Results show similar rates of viral suppression between both immunotherapies when continued during a 4-week ART interruption, despite Peg-IFN-α2a maintaining significantly higher trough blood levels.

Safety, Immune, and Antiviral Effects of Pegylated Interferon Alpha 2b Administration in Antiretroviral Therapy-Suppressed Individuals: Results of Pilot Clinical Trial

In the pilot NCT01935089 trial, we tested whether pegylated interferon alpha2b (Peg-IFN-α2b) with antiretroviral therapy (ART) was safe and could impact HIV and immune measures in blood and in gut-associated lymphoid tissue (GALT). Twenty HIV-1⁺ ART-suppressed individuals received 1 μg/kg/week Peg-IFN-α2b with ART for 20 weeks, with intermediate 4-week analytical ART interruption (ATI). Safety, immune activation, HIV viral load and integrated HIV DNA in blood, and HIV RNA and DNA in gut biopsies were measured. A total of 7/20 participants experienced grade 3-4 adverse events, while 17/20 participants completed the study. Of the 17 participants who completed the study, 8 remained suppressed during ATI, while all 17 were suppressed at end of treatment (EoT). As expected, treatment increased activation of T and natural killer (NK) cells and IFN-stimulated molecule expression on monocytes in periphery. While circulating CD4⁺ T cells showed a trend for a decrease in integrated HIV DNA, GALT showed a significant decrease in HIV-1 RNA⁺ cells as measured by in situ hybridization along with a reduction in total HIV DNA and cell-associated RNA by EoT. The observed decrease in HIV-1 RNA⁺ cells in GALT was positively associated with the decrease in activated NK cells and macrophages. This study documents for the first time that 20 weeks of immunotherapy with Peg-IFN-α2b+ART (inclusive of a 4-week ATI) is safe and results in an increase in blood and GALT immune activation and in a significant decrease in HIV-1 RNA⁺ cells in GALT in association with changes in innate cell activation.

Antigenic competition in CD4+ T cell responses in a randomized, multicenter, double-blind clinical HIV vaccine trial

T cell responses have been implicated in reduced risk of HIV acquisition in uninfected persons and control of viral replication in HIV-infected individuals. HIV Gag-specific T cells have been predominantly associated with post-infection control, whereas Env antigens are the target for protective antibodies; therefore, inclusion of both antigens is common in HIV vaccine design. However, inclusion of multiple antigens may provoke antigenic competition, reducing the potential effectiveness of the vaccine. HVTN 084 was a randomized, multicenter, double-blind phase 1 trial to investigate whether adding Env to a Gag/Pol vaccine decreases the magnitude or breadth of Gag/Pol-specific T cell responses. Fifty volunteers each received one intramuscular injection of 1 × 10¹⁰ particle units (PU) of rAd5 Gag/Pol and EnvA/B/C (3:1:1:1 mixture) or 5 × 10⁹ PU of rAd5 Gag/Pol. CD4⁺ T cell responses to Gag/Pol measured 4 weeks after vaccination by cytokine expression were significantly higher in the group vaccinated without Env, whereas CD8⁺ T cell responses did not differ significantly between the two groups. Mapping of individual epitopes revealed greater breadth of the Gag/Pol-specific T cell response in the absence of Env compared to Env coimmunization. Addition of an Env component to a Gag/Pol vaccine led to reduced Gag/Pol CD4⁺ T cell response rate and magnitude as well as reduced epitope breadth, confirming the presence of antigenic competition. Therefore, T cell-based vaccine strategies should aim at choosing a minimalist set of antigens to reduce interference of individual vaccine components with the induction of the maximally achievable immune response.

Recommendations for measuring HIV reservoir size in cure-directed clinical trials

Therapeutic strategies are being clinically tested either to eradicate latent HIV reservoirs or to achieve virologic control in the absence of antiretroviral therapy. Attaining this goal will require a consensus on how best to measure the numbers of persistently infected cells with the potential to cause viral rebound after antiretroviral-therapy cessation in assessing the results of cure-directed strategies in vivo. Current measurements assess various aspects of the HIV provirus and its functionality and produce divergent results. Here, we provide recommendations from the BEAT-HIV Martin Delaney Collaboratory on which viral measurements should be prioritized in HIV-cure-directed clinical trials.

Prevalence of Opportunistic Infections and Causes of Death among Hospitalized HIV-Infected Patients in Sichuan, China

Opportunistic infections (OIs) are the most significant complication of human immunodeficiency virus (HIV) infection. The prevalence of OIs differs among various countries in part due to different climates and socio-economic conditions. We, therefore, carried out the retrospective study at the Public Health Clinical Center of Chengdu, Sichuan to comprehensively investigate the prevalence of OIs, predictors of OIs, and risk factors for in-hospital death among HIV-infected patients. Sichuan in West China is characterized by the largest population living with HIV/Acquired immunodeficiency syndrome (AIDS) across China. In total, we reviewed 954 cases of HIV infection, admitted to the hospital during January 2014 to December 2015, and found that bacterial pneumonia (25.8%) was the most common OIs, followed by candida infection (18.3%), Pneumocystis jiroveci pneumonia (11.9%), tuberculosis (11.5%), infectious diarrhoea (9.3%), cryptococcus infection (7.3%), cytomegalovirus infection (4.9%), toxoplasmosis (4.6%), hepatitis C (4.0%), nontuberculous mycobacteria desease (2.2%) and Penicillium marneffei infection (0.3%). We also found two strongest risk factors for in-hospital mortality: CD4+T cell counts of less than 100 cells/μL and not receiving antiretroviral therapy. Moreover, the study revealed the specific pathogens causing bacterial pneumonia and/or candida infection, the effect of tuberculosis on CD4+T cell counts, and the drug resistance of Mycobacterium tuberculosis among HIV-infected and non-HIV-infected patients. The present findings may aid in the clinical diagnosis and treatment of HIV-infected patients, and could help developing efficient public health strategies in China.

A Fixed Spatial Structure of CD8+ T Cells in Tissue during Chronic HSV-2 Infection

Tissue-resident CD8⁺ T cells (T_rm) can rapidly eliminate virally infected cells, but their heterogeneous spatial distribution may leave gaps in protection within tissues. Although T_rm patrol prior sites of viral replication, murine studies suggest they do not redistribute to adjacent uninfected sites to provide wider protection. We perform mathematical modeling of HSV-2 shedding in Homo sapiens and predict that infection does not induce enough T_rm in many genital tract regions to eliminate shedding; a strict spatial distribution pattern of mucosal CD8⁺ T cell density is maintained throughout chronic infection, and trafficking of T_rm across wide genital tract areas is unlikely. These predictions are confirmed with spatial analysis of CD8⁺ T cell distribution in histopathologic specimens from human genital biopsies. Further simulations predict that the key mechanistic correlate of protection following therapeutic HSV-2 vaccination would be an increase in total T_rm rather than spatial reassortment of these cells. The fixed spatial structure of T_rm induced by HSV-2 is sufficient for rapid elimination of infected cells but only in a portion of genital tract microregions.

Cell-Mediated Immunity to Target the Persistent Human Immunodeficiency Virus Reservoir

Effective clearance of virally infected cells requires the sequential activity of innate and adaptive immunity effectors. In human immunodeficiency virus (HIV) infection, naturally induced cell-mediated immune responses rarely eradicate infection. However, optimized immune responses could potentially be leveraged in HIV cure efforts if epitope escape and lack of sustained effector memory responses were to be addressed. Here we review leading HIV cure strategies that harness cell-mediated control against HIV in stably suppressed antiretroviral-treated subjects. We focus on strategies that may maximize target recognition and eradication by the sequential activation of a reconstituted immune system, together with delivery of optimal T-cell responses that can eliminate the reservoir and serve as means to maintain control of HIV spread in the absence of antiretroviral therapy (ART). As evidenced by the evolution of ART, we argue that a combination of immune-based strategies will be a superior path to cell-mediated HIV control and eradication. Available data from several human pilot trials already identify target strategies that may maximize antiviral pressure by joining innate and engineered T cell responses toward testing for sustained HIV remission and/or cure.

Gag-Specific CD4 T Cell Proliferation, Plasmacytoid Dendritic Cells, and Ethnicity in Perinatally HIV-1-Infected Youths: The ANRS-EP38-IMMIP Study

In perinatally HIV-1-infected youths living in France, we previously reported that Gag-specific CD4 and CD8 T cell proliferation is more frequently detected in patients of black ethnicity than in those of other ethnicities. We observed that black patients had higher levels of dendritic cells (DCs) than other patients. We aimed at studying the association of DC levels with Gag-specific T cell proliferation. The ANRS-EP38-IMMIP study is an observational study of youths aged between 15 and 24 years who were perinatally infected with HIV. A single blood sample was drawn for virological and immunological assays. Data from cART-treated 53 youths with undetectable plasma HIV RNA were analyzed. Gag-specific T cell proliferation was assessed by using a CFSE-based test. Peripheral blood myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs) were phenotyped by flow cytometry. Plasma markers were quantified by ELISA or multiplex assays. Logistic regression was used for univariate and multivariate analyses. Patients with Gag-specific CD4 T cell proliferative responses had significantly higher percentages and absolute counts of mDCs and pDCs in the peripheral blood than nonresponding patients. Gag-specific CD4 and CD8 T cell proliferation was associated with lower plasma sCD14 levels. Plasma levels of IFN-α, TRAIL, and chemokines involved in T cell migration to secondary lymphoid organs were not associated with T cell proliferation. Multivariate analysis confirmed the association between Gag-specific CD4 T cell proliferation and pDC levels. In conclusion, DC levels are a robust correlate of the presence of Gag-specific T cell proliferation in successfully treated youths.

Curing HIV: Moving Forward Faster

There is enormous enthusiasm in the scientific community for finding a cure for HIV. Although much remains to be discovered regarding the mechanisms of viral persistence and how it may be disrupted, some assumptions regarding the goals of a cure, applicability to target populations, and what is required of the assays we employ, may lead to missed opportunities and discoveries and hamper the discovery of a product that will safely cure tens of millions of HIV-infected people around the world. The field will benefit from an awareness and critical interrogation of assumptions that may be implicit in their scientific pursuits.

Prolonged Antiretroviral Therapy Preserves HIV-1-Specific CD8 T Cells with Stem Cell-Like Properties

HIV-1-specific CD8 T cells can influence HIV-1 disease progression during untreated HIV-1 infection, but the functional and phenotypic properties of HIV-1-specific CD8 T cells in individuals treated with suppressive antiretroviral therapy remain less well understood. Here we show that a subgroup of HIV-1-specific CD8 T cells with stem cell-like properties, termed T memory stem cells (TSCM cells), is enriched in patients receiving suppressive antiretroviral therapy compared with their levels in untreated progressors or controllers. In addition, a prolonged duration of antiretroviral therapy was associated with a progressive increase in the relative proportions of these stem cell-like HIV-1-specific CD8 T cells. Interestingly, the proportions of HIV-1-specific CD8 TSCM cells and total HIV-1-specific CD8 TSCM cells were associated with the CD4 T cell counts during treatment with antiretroviral therapy but not with CD4 T cell counts, viral loads, or immune activation parameters in untreated patients, including controllers. HIV-1-specific CD8 TSCM cells had increased abilities to secrete interleukin-2 in response to viral antigen, while secretion of gamma interferon (IFN-γ) was more limited in comparison to alternative HIV-1-specific CD8 T cell subsets; however, only proportions of IFN-γ-secreting HIV-1-specific CD8 TSCM cells were associated with CD4 T cell counts during antiretroviral therapy. Together, these data suggest that HIV-1-specific CD8 TSCM cells represent a long-lasting component of the cellular immune response to HIV-1 that persists in an antigen-independent fashion during antiretroviral therapy but seems unable to survive and expand under conditions of ongoing viral replication during untreated infection.

IMPORTANCE

Memory CD8 T cells that imitate the functional properties of stem cells to maintain lifelong cellular immunity have been hypothesized for many years, but only recently have such cells, termed T memory stem cells (TSCM cells), been physically identified and isolated in humans, mice, and nonhuman primates. Here, we investigated whether cellular immune responses against HIV-1 include such T memory stem cells. Our data show that HIV-1-specific CD8 T memory stem cells are detectable during all stages of HIV-1 infection but occur most visibly at times of prolonged viral antigen suppression by antiretroviral combination therapy. These cells may therefore be particularly relevant for designing antiviral immune defense strategies against the residual reservoir of HIV-1-infected cells that persists despite treatment and leads to viral rebound upon treatment discontinuation.