1 School of Pathology and Laboratory Medicine, University of Western Australia

1. Expression of interferon-stimulated gene transcripts is up-regulated in CD4+ T-cells from HIV patients with low CD4+ T-cell recovery after ART Sara Tanaskovic1, Sonia Fernandez1, Karla Helbig3, Michael Beard3, Patricia Price1, Martyn French1,2 1School of Pathology and Laboratory Medicine, University of Western Australia 2Department of Clinical Immunology & Immunogenetics, Royal Perth Hospital, Western Australia 3School of Molecular Biosciences, University of Adelaide, Adelaide, Australia

2. BACKGROUND: • Up to 30% of HIV infected patients receiving ART do not achieve an optimal increase in their circulating CD4+ T-cell numbers despite long-term suppression of HIV replication • Poor recovery of CD4+ T-cell numbers is associated with persistently high levels of immune hyperactivation • It remains unclear how immune hyperactivation impairs CD4+ T-cell recovery • Activated CD4+ T-cells may be influenced by type 1 interferons which adversely affect CD4+ T-cell survival OBJECTIVES: • We investigated the relationship between expression of interferon stimulated gene (ISG) transcripts, immune hyperactivation & CD4+ T-cell recovery in HIV patients receiving long-term ART

3. PATIENT COHORTS & METHODS • 42 adult HIV-1 individuals: • advanced immunodeficiency (nadir <50 CD4+ T-cells/µl) • on ART > 12 months • undetectable virus  6 months • The median naïve CD4+ T-cell count was used to categorise patients into low & high groups (naïve CD4+ T-cell count > or <85/µl) • mRNA expression for three ISGs (IF16016, IF127 & ISG56) was quantified by PCR in immunomagnetically purified CD4+ and CD8+ T-cells High CD4+ recovery group (n=21) naïve CD4+ T-cell count>85/µl Low CD4+ recovery group (n=21) naïve CD4+ T-cell count <85/µl

4. The proportion of CD4+ T-cells expressing HLA-DR , CD57 and Fas was higher in patients with low CD4+ T-cell counts than those with high CD4+ T-cell counts p=0.03 p=0.04 p=0.01 p=0.18 p=0.03 p=1.0 RESULTS: HLA-DR CD57 Fas p=0.03 p=0.04 p=0.01 • The proportion of CD8+ T-cells expressing CD57 was higher in patients with low CD4+ T-cell counts than those with high CD4+ T-cell counts, however this trend was not observed with HLA-DR or Fas

5. RESULTS: *** p<0.05 *** p<0.005 *** p<0.0005 • mRNA levels of IF16-16, IF127 & ISG56 in CD4+ T-cells were higher in HIV patients with low CD4+ T-cell counts • mRNA levels of IF16-16, IF127 & ISG56 in CD8+ T-cells did not differ between HIV patients with low & high CD4+ T-cell counts, but were elevated when compared to controls • No relationship was observed between the expression of ISG transcripts and immune activation markers

6. CONCLUSIONS: • Immune hyperactivation is elevated in HIV patients with low numbers of circulating naïve CD4+ T-cells • Expression ISG transcripts in total CD4+ T-cells was higher in HIV patients with low naïve CD4+T-cell counts than in patients with high naïve CD4+ T-cell counts and controls • Expression of ISG transcripts in total CD8+ T-cells did not differ between HIV patients in the high or low naïve CD4+ T-cell groups, although ISG expression was elevated in comparison to controls • The lack of correlation observed between ISG transcripts and expression of T-cell activation and pro-apoptotic molecules suggests that up-regulation of ISG transcripts may influence cell survival via a pathway that does not involve Fas, such as TRAIL and DR5