CROI 2015 Program and Abstracts

Abstract Listing

Oral Abstracts

Results: The median CD4+ T cell count was 16/ m L and log 10 cryptococcal antigen (CrAg) titer of 1:4,000 and cryptococcal colony forming units of log 10 5.4/mL. Total IgG in CSF exceeded IgM by over 20 fold (median 127 vs. 5.8 m g/mL). Levels of IgG and IgM specific to GXM were greater than levels specific to unencapsulated organisms. We detected GXM-specific IgG and IgM in CSF of 46% and 24% of subjects, respectively, and in 100% of sera. The antibodies detected in CSF were specific for GXM based on cross-adsorption with heterologous polysaccharides and proteins, but the specificity of IgM exceeded that of IgG. In the CSF, GXM-IgM was produced locally, whereas the GXM-IgG was likely transferred from serum based on the ratios of GXM-specific to total IgM and IgG in CSF and serum. The majority of GXM-IgG but not IgM in the CSF was bound by local capsular GXM as levels increased by 10-fold upon dissociation of IC. IC-bound antibodies had greater avidity than antibodies freely circulating in CSF. Levels of GXM-IgG or -IgM did not correlate with CSF WBC, protein, CrAg titer or mortality (11 of 41 died [26.8%] within 30 days). Conclusions: Specific antibodies that recognize the predominant capsular polysaccharide of C. neoformans (GXM) are present in the CSF of a subset of AIDS patients with CM. GXM-IgM, although present in fewer patients, was higher in concentration, specificity and avidity than GXM-IgG and was more likely produced locally at the site of infection. Enhancing levels of such antibodies may support opsonization of C. neoformans , promote cytokine production and cellular immune responses to the organism, and thereby faciliate protection against these common and often fatal infections. 835 Antiretroviral Therapy Alters the CSF Immune Response in Cryptococcal Meningitis James E. Scriven 1 ; Britta Urban 1 ; Lisa Graham 2 ; Charlotte Schutz 2 ; Robert J.Wilkinson 3 ; David R. Boulware 4 ; David Lalloo 1 ; Graeme Meintjes 2 1 Liverpool School of Tropical Medicine, Liverpool, United Kingdom; 2 University of Cape Town, Cape Town, South Africa; 3 Imperial College London, London, United Kingdom; 4 University of Minnesota, Minneapolis, MN, US Background: Cryptococcal meningitis (CM) is an important opportunistic infection in sub-Saharan Africa. Animal models suggest a M2 (alternatively activated) macrophage phenotype and Th2 response are detrimental during infection but studies in humans are limited. To address this we characterized the CSF immune response in HIV-associated CM, examined the effects of ART, and explored the relationship between CSF immune response, fungal burden and mortality. Methods: A prospective cohort study was conducted in South Africa. Persons with CM were enrolled and followed for 12 weeks. CSF immune response was examined using 11- colour flow cytometry and 17-plex luminex analysis. Fungal burden was measured using quantitative culture. Data were analysed using principal component analysis; p<0.05 with a false discovery rate (q) <0.1 were used to infer statistical significance. Results: 57 subjects were enrolled: 42 not taking ART, 8 on effective ART and 7 with virological failure on ART. Median CD4 count was 34 cells/ μ L and median CSF WCC 18/ μ L. CD8 T cells were the most frequent CSF cell followed by neutrophils, macrophages and CD4 T cells (median 50%, 12%, 6.7% and 6.2%WCC respectively). Compared to individuals not on ART, the CSF of those taking effective ART had significantly increased CD4 T cells, decreased CD8 T cells, increased CD4/CD8 ratio and increased CD206 expression on CD14+ and CD14- macrophages - suggesting M2 phenotype ( table 1 ). CD206 expression was inversely correlated with plasma viral load (even in persons not taking ART (r=-0.59, p=0.0001)) but was not associated with fungal burden (r=-0.02, p=0.893). Fungal burden was inversely correlated with CSF GCSF, IL6, CD4, CD8, CD4-CD8- and NK cells (r= -.49, -.41 -.61, -.55, -.49, -.40 respectively; all p <.05 and q<.1). Non-survivors had decreased CSF CD4-CD8- T cells and reduced CSF IFN γ but this was not significant when adjusted for multiple comparisons (p=.021 q=.92; p=.038, q=.97; respectively). HIV RNA was 5.33 copies/mL. CSF-analysis showed median protein of 70 mg/dL, WBC of 30/mL [43% had <5 cells],

Oral Abstracts

Table 1. Immune parameters that differed significantly between subjects taking effective ART and those who were not. Geometric means are displayed; parametric tests were performed on log2 transformed variables. Q values refer to the false discovery rate. “Large T cells” were a secondary population of T cells with increased forward scatter. WCC=white cell count; M=macrophage Conclusions: In CM, ART is associated with an increased CSF CD4/CD8 ratio and an increased M2 macrophage phenotype, likely mediated through effects on HIV viral load. In contrast to animal data the M2 phenotype was not associated with increased fungal load or fatal outcome. Instead, fungal burden was negatively correlated with CSF T cells (CD8, CD4 and CD4-CD8-) and concentrations of pro-inflammatory cytokines. This is supportive of the theory that a paucity of CSF inflammation is associated with severe disease in CM. 836 Detrimental Outcomes of Unmasking Cryptococcal Meningitis With Recent ART Initiation Background: Cryptococcal meningitis (CM) remains a major cause of HIV-related mortality in Africa. Increased antiretroviral therapy (ART) availability coupled with a lack of pre-ART cryptococcal antigen screening has led to a greater proportion of patients developing CM after initiating ART. Despite this changing epidemiology, data regarding CM in patients already receiving ART are lacking. We compared the clinical presentation and outcomes in ART-naïve and ART-experienced Ugandans. Methods: We enrolled a prospective cohort of 165 HIV-infected persons with cryptococcosis in Kampala, Uganda from Aug 2013 to Aug 2014. Subjects were classified by ART status, the timing of ART initiation, and previous CM history. The primary endpoint was 2-week mortality. Statistical comparisons were made with Kruskal-Wallis or Fisher’s Exact tests. Results: 87% (144/165) of subjects presented with their first episode of CM whereas 13% (21/165) had a previous history of CM. Of those with first CM episode, 40% (58/144) were receiving ART at presentation, having initiated ART a median of 110 (IQR, 20-519) days prior to CM diagnosis. Those receiving ART had higher CD4 (median 32 (IQR, 10-73) vs 12 (IQR, 6-39) cells/mcL; p =.02) and lower CSF fungal burdens (median 4.0 (IQR, 2.5-4.9) vs 4.8 (IQR, 3.9-5.6) log 10 CFU/mL CSF; p <.001). 55% (32/58) had initiated ART within the last 4 months, and 22% (13/58) initiated ART within the last 14 days. Persons starting ART <4 months prior were more likely to present with altered mental status (44% vs 19% with GCS<15, p =.05) despite having lower CSF fungal burdens (median 3.7 (2.3-4.3) vs 4.5 (3.4-5.1) log 10 CFU/mL; p =.04) compared to those initiating ART >4 months prior to Joshua Rhein 1 ; Katherine H. Hullsiek 1 ; Nathan C. Bahr 1 ; Reuben Kiggundu 3 ; DarlishaWilliams 3 ; HenryW. Nabeta 3 ; Abdu Musubire 3 ; David B. Meya 3 ; David R. Boulware 1 1 University of Minnesota, Minneapolis, MN, US; 2 University of Minnesota, Minneapolis, MN, US; 3 Makerere University College of Health Sciences, Kampala, Uganda

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CROI 2015