CROI 2016 Abstract eBook

Abstract Listing

Poster Abstracts

667 Variation in EraP Influencees Risk for HLA-B*57:01 Positive Abacavir Hypersensitivity Rebecca Pavlos 1 ; Kaija Strautins 1 ; Ian James 1 ; Simon Mallal 1 ; Alec Redwood 1 ; Elizabeth J. Phillips 2 1 Inst for Immunology & Infectious Diseases, Murdoch Univ, Murdoch, Australia; 2 Vanderbilt Univ Sch of Med, Nashville, TN, USA

Background: Abacavir (ABC) binds non-covalently to the floor of the peptide-binding groove of HLA-B*57:01, altering the chemistry and shape of the antigen binding cleft. This allows previously untolerized self-peptides to be presented by HLA-B*57:01 which upon T-cell receptor binding initiates a CD8+ T-cell response and a clinical hypersensitivity reaction(HSR). Endoplasmic reticulum aminopeptidases (ERAPs) trim peptides for MHC Class I presentation, influencing the degree and specificity of the CD8+ T-cell response. Genetic variation within ERAP adds to the positive predictive value (PPV) of the HLA class I risk allele in autoimmune diseases such as HLA-B27 positive ankylosing spondylitis. Considering the altered peptide repertoire mechanism of ABC HSR we hypothesize that variation in ERAP may help explain why 45% carrying HLA-B*57:01 can tolerate ABC. Methods: SNPs within ERAP1 (rs27044, rs17482078, rs30187, rs27434, rs2287987) were examined in HLA-B*57:01+ ABC HSR patch test positive (PT+)[n=53] and HLA-B*57:01+ ABC tolerant[n=22] with sequence-based typing. Rs2248374, a tag SNP for functional ERAP2 haplotypes was also examined. Haplotype A is tagged by the (A) allele, while haplotype B is tagged by rs2248374(G). Fisher exact tests and multiple logistic regressions were used to compare genotypes between the ABC HSR PT+ and tolerant groups. Results: HLA-B*57:01+ ABC tolerance was associated with rs27434(GG) (18/22(82%) vs 24/53(45%) in ABC HSR PT+, p=0.005). This SNP maps to the active site within ERAP1 (AA356). For an HLA-B*57:01 positive population the estimated PPV for rs27434 genotypes for ABC HSR PT+ is AA(100%), AG(77%) and GG(40%). A missense mutation within the domain junction (rs30187(C)) important in conformation change of ERAP1 (AA528), was overrepresented in HLA-B*57:01+ ABC tolerant individuals (p=0.04). Analysis indicated linkage between rs27044 and rs30187, rs17482078 and rs2287987, and between rs30187 and rs27434 (all p < 0.0001). In a multivariable model with rs27434(GG), the ERAP2 SNP (rs2248372(G)) that tags haplotype B which is characterized by a truncated protein, was decreased in tolerant individuals (p = 0.005). Conclusions: ERAP and particularly ERAP1 variants are important in the development of ABC HSR. ERAP activity may influence the repertoire of peptides presented by HLA- B*57:01 or influence early changes in immunodominant epitope selection. This provides a potential pathogenic mechanism for the development of ABC HSR or ABC tolerance in HLA-B*57:01 carriers. 668 AZT/NNRTI Induce Greater Adipose Tissue Mitochondrial Toxicity Than AZT/PI Robert T. Maughan 1 ; Elena Alvarez 1 ; Anthony Kelleher 2 ; David Cooper 3 ; Andrew Carr 4 ; Patrick Mallon 1 ; for the HAMA001 Study Investigators 1 Univ Coll Dublin, Dublin, Ireland; 2 Univ of New South Wales, Sydney, Australia; 3 Kirby Inst, Sydney, Australia; 4 St Vincent’s Hosp, Sydney, Sydney, Australia Background: Use of AZT in antiretroviral therapy (ART) is associated with subcutaneous adipose tissue (SAT) and mitochondrial toxicity (MtTox). However, detailed molecular analyses of the additional contribution of protease inhibitors (PI) and non-nucleoside reverse transcriptase inhibitors (NNRTI) to this toxicity are lacking. Methods: In a prospective cohort study, ART-naïve HIV+ subjects initiating ART containing AZT/PI, AZT/NNRTI or non-AZT/non-PI underwent assessments of clinical, demographic parameters and limb fat (LF) by DXA at wks 0, 12, 24 and 48. Mitochondrial DNA (mtDNA) and expression of 55 key insulin signalling, lipid metabolism and mitochondrial function genes were measured by qPCR in fasting SAT biopsies fromwks 0, 2 and 48. Associations between treatment groups and parameter changes were analysed by adjusted longitudinal marginal models, gene expression by LIMMA in R, with data presented as model parameter estimates (PE [95% CI]). Results: 23 subjects were recruited, median [IQR] age 39 [34, 48] yrs, 91% Caucasian, 87%male, CD4+ count 132 [58, 228] cells/mm 3 , log HIVRNA 4.97 [4.51, 5.57] cps/ml. Over 48 weeks, LF increased as expected with non-AZT/non-PI ART (+30.5 [+11.9, +49.1] g/wk) with significantly lower LF gains in the AZT/PI and AZT/NNRTI groups (-15.7 [-45.7, +14.2], P =0.005 and +4 [-29.3, +21.3] g/wk, P =0.012 respectively). Initiation of ART led to decreased expression of inflammatory genes in groups overall, including CCL2 ( P =0.017) and IL6 ( P =0.017, P =0.033). The largest mtDNA decreases occurred with AZT/NNRTI ART (-10.2 [-20, -0.6] cps/cell/wk), being significantly greater than both AZT/PI and non-AZT/ non-PI ART groups (P.E. +3.2 [-8, +14.3], P =0.001 and +2.2 [-5.2, +9.5], P =0.015 respectively, fig.1). Consistent with MtTox, this group also had upregulated expression of the mitochondrial biogenesis gene TFAM ( P =0.012) and decreases in key metabolic genes LEP and INSR at week 48 ( P =0.013 and P =0.049 respectively), none of which were observed in the other two groups. In fact expression of several key adipocyte genes increased at week 48; PPARG and FABP4 with AZT/PI ( P =0.021 and P =0.001) and Adiponectin with non-AZT/non-PI ( P =0.006) . Conclusions: These data suggest greater SAT MtTox with AZT/NNRTI ART than either AZT/PI or non-AZT/non-PI. However, changes in LF did not differ significantly between AZT- treated groups. These findings support emerging data on NNRTIs contribution to thymidine-NRTI toxicity, suggesting additive MtTox as an underlying mechanism.

Poster Abstracts

669

Regulation of Telomerase Activity in PBMCs Exposed to Antiretroviral Drugs Natalia C. Stella Ascariz 1 ; Rocío Montejano 1 ; Laura Pintado 2 ; Susana Monge 3 ; José I. Bernardino 1 ; Ignacio Pérez-Valero 1 ; Maria L. Montes 1 ; Jesús Mingorance 1 ; Rosario Perona 2 ; Jose R. Arribas 1 1 Inst for Hlth Rsr of La Paz Univ Hosp, Madrid, Spain; 2 Inst de Investigaciones Biomédicas, Madrid, Spain; 3 Univ de Alcalá, Madrid, Spain Background: Telomere attrition is one of the hallmarks of aging. It is unknown if this mechanism contributes to accelerated aging in HIV infected patients. One single prior study has shown that tenofovir (TFV) is a potent inhibitor of telomerase activity in vitro (J Inf Dis 2013; 207:1157). We sought to confirm this finding and to evaluate the possible impact of different antiretrovirals on expression of telomerase genes. Methods: Activated peripheral blood mononuclear cells (PBMCs) from healthy donors were treated with increased concentration of TFV, abacavir (ABC), emtricitabine (FTC) or darunavir (DRV) for 72 hours. We determined telomerase activity, levels of human telomerase reverse transcriptase (hTERT) protein and expression of the genes coding for the different telomerase complex subunits (hTERT, TERC, DKC1, TINF2, TRF1 and TRF2). All results are expressed relative to untreated cells. Telomerase activity was measured using telomeric repeat amplification protocol (TRAP), levels of hTERT were determined by western blot and mRNA levels were measured by qPCR using TAQman probes in

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