CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

Background: Gamma/delta T cells constitute an attractive alternative/ complementary effector population as they exert potent cytotoxic and antiviral functions. Cancer immunotherapy using gamma/delta T cells and pamidronate (PAM) has been extensively developed. Our objective is to analyze the immunotherapeutic potential of gamma/delta T cells to clear reactivated HIV. Methods: Cells from HIV-infected donors on suppressive ART were studied in autologous cellular systems using isolated cells. Vdelta2 cells were expanded with PAM and IL-2 for 14 days. Activation, exhaustion and cytotoxic markers of expanded Vdelta2 cells was analyzed by flow cytometry. Cytotoxic assays were assessed measuring CD107a expression by flow cytometry. For inhibition assays, infected CD4 cells were co-cultured with Vdelta2 cells. Latency clearance assays were performed to analyze the capacity of gamma/delta T cells to clear viral production after autologous resting CD4 cells had been reactivated using vorinostat. Results: Vdelta2 cells from HIV-infected individuals expanded up to 120-fold after 14 days in culture. 65% of expanded Vdelta2 cells display markers of a central memory phenotype, 23%were transitional memory and 8%were effector memory. 37% of the expanded Vdelta2 cells expressed CD8, 50% displayed a cytotoxic phenotype (Vdelta2+CD56+) and 30% displayed an ADCC-like phenotype characterized by the expression of CD16. Cytotoxic assays showed significantly higher expression of CD107a when expanded Vdelta2 cells were cultured with HIV-superinfected CD4 cells compared to non-superinfected CD4 cells. Viral inhibition assays showed that expanded Vdelta2 cells are potent inhibitors of HIV p24 antigen production showing a mean of 85% reduction, compared to viral production by CD4 cells alone. Finally, latency clearance assays demonstrated lower recovery of replication-competent HIV after reactivation of autologous resting CD4 cells when gamma/delta T cells were present in the coculture system. Conclusion: Our results support that gammadelta cells immunological functions are maintained in HIV-infected individuals and that their antiviral activity can be expanded ex vivo to target the HIV reservoir in fully suppressed individuals upon latency disruption. This is the first proof-of-concept showing that gammadelta cells remain able to target and clear autologous HIV reservoir and suggest that gammadelta cells are strong candidates to current immunotherapeutic interventions aimed for HIV reservoir eradication strategies. 355 BLOCKADE OF IFNAR RESCUES ANTI-HIV-1 CD8 T CELL FUNCTIONS TO REDUCE HIV-1 RESERVOIR Liang Cheng 1 , Jianping Ma 1 , Guangming Li 1 , Zhiyuan Hu 1 , Liguo Zhang 2 , Lishan Su 1 1 University of North Carolina Chapel Hill, Chapel Hill, NC, USA, 2 Chinese Academy of Sciences, Beijing, China Background: Type I interferons (IFN-I) are critical for controlling virus infections, but their persistent expression also contributes to impaired host immunity and virus persistence. Although IFN-I inhibit HIV-1 replication in vitro and in vivo, persistent IFN-I induction is correlated with immune dysfunction and disease progression in HIV-1 infected patients and in SIV infected monkeys. Moreover, despite efficient suppression of HIV-1 replication with combined antiretroviral therapy (cART), low levels of IFN-I signaling persist in some individuals, which may impede immune recovery and foster viral persistence. Methods: We developed a monoclonal antibody to human IFN-α/β receptor (α- IFNAR) which can block IFN-I signaling in vivo. Humanized mice with persistent HIV-1 infection were treated with cART and IFNAR blockade Ab or isotype control (and human CD8 depleting mAb). At termination, T cell phenotype (expression of activation marker CD38 and HLA-DR, exhaustion marker PD-1, TIM3) was detected by FACS. T cell function was detected by ex vivo HIV-1 Gag peptide pool stimulation followed with IL-2/IFN-γ/TNF-α intracellular staining. Transcriptome analyses by RNA-seq were performed with purified human CD8 T cells to identify pathways and genes contributing to IFN-I-induced T cell dysfunction. To measure HIV-1 reservoir, we detect cell-associated HIV-1 DNA and RNA by PCR, and replication-competent HIV-1 by the quantitative virus outgrowth assay(QVOA). In addition, we measured virus rebound after cART discontinuation. Results: In HIV-infected humanized mice with cART, IFNAR blockade reduces the level of T cell activation (expression of CD38 and HLA-DR), reverses T cell exhaustion (expression of PD-1 and TIM-3). Transcriptome analysis by RNA-seq with purified CD8 T cells also indicated that IFNAR blockade reduced the expression of ISGs and genes involved in immune activation, exhaustion and cell

353LB IL-15 TREATMENT INCREASES CYTOTOXIC LYMPHOCYTES IN LN FOLLICLES AND REDUCES SHIV RNA George Pavlakis 1 , Dionysios C. Watson 1 , Eirini Moysi 1 , Antonio Valentin 1 , Cristina Bergamaschi 1 , Santhi Devsundaram 1 , Sotirios Fortis 1 , Claire Deleage 2 , Jacob D. Estes 2 , Elena Chertova 2 , Jeffrey D. Lifson 2 , Constantinos Petrovas 3 , Barbara K. Felber 1 1 NIH, Frederick, MD, USA, 2 Leidos Biomedical Research, Inc, Frederick, MD, USA, 3 NIAID, Gaithersburg, MD, USA Background: Heterodimeric interleukin-15 (hetIL-15) is a native stable form of the cytokine that activates and expands cytotoxic T and NK cells. Based on its properties and extensive preclinical data, hetIL-15 is currently evaluated in humans for the treatment of cancer. We study the effects of hetIL-15 in infected macaques to evaluate its use in HIV infection and especially in the reduction of SIV/SHIV reservoir towards a functional cure. Methods: Rhesus macaques, either chronically infected by SHIV or uninfected received injections of hetIL-15 over 2 weeks using increasing doses of cytokine (step-dosing). At the end of the treatment, the animals were sacrificed and the hetIL-15 effects on different lymphocyte populations isolated from tissues collected at necropsy were monitored by multi-parametric flow cytometry and quantitative multiplexed confocal microscopy (histo-cytometry). Cell- associated viral RNA and plasma viral load was measured by quantitative PCR. Results: This protocol was safe in rhesus macaques and resulted in systemic expansion of CD8+ T lymphocytes and NK cells with higher granzyme B content. These expanded cell populations were found in both effector sites, such as liver, vagina and rectum, and secondary lymphoid tissues. Importantly, a significant increase in cytotoxic effector memory CD8+ T cells was found in lymph nodes (LN) from all hetIL-15-treated macaques. CM9 tetramer staining demonstrated that the increase of CD8+ effector T cells in lymphoid organs included actively proliferating SIV-specific T cells with higher granzyme content. Imaging analysis by histo-cytometry revealed that these effector CD8+ T cells infiltrated the B cell follicles where chronically infected follicular helper CD4+ T cells are located. Following hetIL-15 treatment, cell-associated RNA was decreased in LN and plasma viral load was also decreased. Treatment of macaques under Antiretroviral Therapy (ART) with this regimen was also safe and induced cytotoxic CD8+ accumulation in LN follicles. Conclusion: Step-dose administration of hetIL-15 is a well-tolerated regimen that results in systemic activation and expansion of cytotoxic leukocytes that infiltrate areas where chronic HIV-infected cells reside. These results suggest that hetIL-15 could be useful in disrupting sanctuary sites within the B cell follicles and reducing long-term viral reservoirs in HIV-1 infected individuals, thus contributing to a functional cure of the infection.

Poster Abstracts

354 GAMMA/DELTA CELLS TARGET THE HIV RESERVOIR: IMMUNOTHERAPEUTIC POTENTIAL FOR HIV CURE

Chloe Whitworth, Carolina Garrido, Katherine Sholtis, Matthew Clohosey, Nancie Archin, David M. Margolis, Natalia Soriano-Sarabia University of North Carolina Chapel Hill, Chapel Hill, NC, USA

CROI 2018 124