CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

679 Dys-Regulated Cross Talk Between CD4+ T Cells and NK Cells in HIV/HCV Coinfection Benjamin Krämer 1 ; Andreas Glässner 1 ; Claudia Zwank 1 ; Felix Goeser 1 ; Christoph Boesecke 1 ; Patrick Ingiliz 2 ; Christian P. Strassburg 1 ; Ulrich Spengler 1 ; Jürgen Rockstroh 1 ; Jacob Nattermann 1 1 University of Bonn, Bonn, Germany; 2 Medical Center for Infectious Diseases, Berlin, Germany Background: HCV/HIV co-infection is associated with an accelerated progression of liver disease as compared to HCV mono-infection. Natural killer cells are considered to play an important role in hepatits C. Increasing data indicate that CD4+ T cells critically modulate NK cell activity. Dys-regulation of the CD4+ T cell pool is a hallmark of HIV infection. Thus, we speculated that an altered cross-talk between CD4+ T cells and NK cells might be involved in the immunopathogenesis of HIV/HCV co-infection. Methods: 40 HIV-infected patients, including 21 individuals that were HIV RNA(-)(<40 copies/ml) under HAART and 19 therapy-naïve HIV RNA(+) patients, as well as 20 healthy controls were enrolled into this study. CD3/CD28 stimulated CD4+ T cells were analysed for IL-2 secretion by flow cyotmetry. Antiviral activity of total PBMCs was studied using the HCV-replicon system. IFN-g secretion and anti-HCV activity of NK cells were analyzed in the presence/absence of CD4+ T cells. Results: PBMCs from HIV(+) were significantly less effective in blocking HCV replication than cells from healthy controls (p<0.001). We also observed HIV infection to be associated with a significantly impaired IFN-g secretion of NK cells (p<0.001). Inhibition of HCV replication as well as IFN-g secretion of NK cells was positively correlated with CD4+ T cell counts in untreated HIV RNA(+) (p<0.05) but not in those under effective HAART. Moreover, we found viraemic HIV infection to be associated with reduced IL2 secretion of CD4+ T cells compared to healthy controls and HIV RNA(-). In line with previous results of our group we found activated CD4+ T cells to effectively stimulate IFN-g secretion of NK cell from healthy controls. Surprisingly, the ability of CD4+ T cells from healthy controls and HIV(+) to trigger activity of healthy NK cell did not differ significantly. However, when NK cells from HIV(+) were tested we found that neither autologous CD4+ T cells nor cells from healthys were able to trigger IFN-g secretion, indicating an NK cell intrinsic defect. Of note, this dys-regulated ability to respond to CD4+ T cell-mediated stimulation was also seen in HIV(+) patients under effective HAART. Conclusions: Our findings indicate that HIV infection is associated with a dys-regulated cross-talk between CD4+ T cells and NK cells, resulting in an impaired anti-HCV NK cell activity which might represent a novel mechanism involved in accelerated progression of HCV-associated liver disease in HIV co-infected patients. 680 HIV/HCV Coinfection Is AssociatedWith Significant Alterations of the NK Cell Pool Dominik J. Kaczmarek 1 ; Pavlos Kokordelis 1 ; Benjamin Krämer 1 ; Andreas Glässner 1 ; FranziskaWolter 1 ; Patrick Ingiliz 2 ; Christian P. Strassburg 1 ; Ulrich Spengler 1 ; Jürgen Rockstroh 1 ; Jacob Nattermann 1 1 University of Bonn, Bonn, Germany; 2 Medical Center for Infectious Diseases, Berlin, Germany Background: Hepatitis C virus (HCV) co-infection in HIV(+) patients is associated with faster progression of liver disease as compared to HCV mono-infection. Natural killer (NK) cells critically modulate the natural course of hepatitis C. Of note, chronic infection with HCV as well as HIV mono-infection have been shown to be associated with significant alterations of the NK cell pool. However, little data is available concerning phenotype and function of NK cells in HIV/HCV infection. Methods: A total of 22 HIV/HCV patients were enrolled into this study. As control 70 patients with chronic hepatitis C, 39 HIV mono-infected patients and 55 healthy individuals were analyzed. NK cell phenotype as well as IFN- γ production and degranulation of NK cells were studied by flow cytometry. Results: Frequency of NK cells in HIV(+) patients was significantly lower than in healthy individuals (p<0.01) irrespective of HCV co-infection but did not differ significantly to that observed in HCV mono-infected patients. Moreover, HIV/HCV co-infection was associated with significantly decreased expression of the NK maturation/differentiation markers CD27, CD127, CD62L and CD161 compared to healthy controls (p<0.01 for each comparison). Of note, expression of these markers in HIV(+)/HCV(+) also differed significantly from that observed in HCV mono-infected patients but was similar to HIV(+)/HCV(-) patients, indicating that these alterations were mainly attributable to HIV infection. Similar observations were made regarding expression of C-type lectin NK cell receptors with low NKG2A but high NKG2C expression in HIV(+) patients, irrespective of HCV co- infection (p<0.01 vs. HCV or healthy). In contrast, we found HIV/HCV co-infection to be associated with a significantly lower frequency of NKp30-expressing NK cells compared to both HCV and HIV mono-infected patients (p<0.001), suggesting a synergistic effect of both viruses. More importantly, we found NK cells from co-infected patients to display highly dys-regulated functional activity with significantly lower IFN- γ production and degranulation than in healthy donors and HIV or HCV mono-infected patients (both p<0.01 for each comparison). Conclusions: Our data indicate that HIV/HCV co-infection is associated with significant alterations of NK cell phenotype and functions, which might be involved in the rapid progression of liver disease observed in co-infected patients. 681 Dynamic Changes of CXCL10 Isoforms and DPP4 During IFN-Free Treatment for HCV Eric G. Meissner 1 ; Jeremie Decalf 2 ; Armanda Casrouge 2 ; Henry Masur 3 ; Shyam Kottilil 4 ; Darragh Duffy 2 ; Matthew L. Albert 2 1 Medical University of South Carolina, Charleston, SC, US; 2 Institut Pasteur, Paris, France; 3 National Institutes of Health (NIH), Bethesda, MD, US; 4 University of Maryland School of Medicine, Baltimore, MD, US Background: The intrahepatic endogenous interferon response fails to promote hepatitis C virus (HCV) clearance once chronic infection is established. The interferon (IFN)- stimulated chemokine CXCL10 (IP-10) is hepatically produced in chronic infection. A short CXCL10 isoformwith antagonistic properties is generated by DPP4 activity, and likely contributes to impaired immunity in chronic HCV infection. We previously showed that IFN-free treatment of chronic HCV with sofosbuvir and ribavirin (SOF/RBV) is accompanied by rapid down-regulation of endogenous interferon activity. There was a trend towards higher pre-treatment CXCL10 levels in eventual relapsers (p=0.12, 994 pg/ml SVR (n=28), 1249 pg/ml relapsers (n=14)). Here, we examined how antagonistic, agonistic, and total CXCL10 levels and DPP4 activity changed during therapy, and whether they were associated with treatment outcome. Methods: Serumwas analyzed from patients who achieved SVR (n=11) or who relapsed (n=10) after treatment with 24 weeks of SOF/RBV on the NIH/NIAID SPARE trial (NCT01441180). Total, antagonistic, and agonistic CXCL10 was measured by Simoa (Quanterix) assay in triplicate at day 0, day 7, and week 20 of treatment. DPP4 levels were measured by ELISA and activity by DPP-Glo™ Protease assay (Promega). Data were analyzed by the Mann Whitney t-test or by Pearson correlation using Prism 6.0 software. Results: In this cohort of patients, agonist (p=0.038) and total (p=0.0079) CXCL10 were significantly higher pre-treatment in patients who later relapsed, while the N-terminal truncated form of CXCL10 did not differ (p=0.31). All forms of CXCL10 decreased rapidly on treatment irrespective of treatment outcome. DPP4 activity correlated with pre- treatment levels of antagonistic CXCL10 (p=0.0027), but not agonistic or total CXCL10. Interestingly, there was no change in DPP4 activity or levels by week 1 of treatment, when all CXCL10 isoforms had declined, while activity had declined by week 20 of treatment. In patients who relapsed, CXCL10 concentration and DPP4 activity returned to pre-treatment levels. Conclusions: Pre-treatment total and agonistic CXCL10, but not the antagonistic DPP4 cleavage product, were associated with treatment outcome in this subset of patients. The delayed kinetic decline of DPP4 activity relative to CXCL10 expression suggests the DPP4 pathway is not immediately regulated by endogenous interferon, providing insight into hepatic immune regulation during IFN-free HCV therapy.

Poster Abstracts

423

CROI 2015