Oral Abstract Session 01 - Global HIV Vaccine Enterprise

POSTERS
Posters
Topic 11: T Cell Immunity
P11.23
Plasma Cytokine Levels and HIV-Specific Immune
Responses During Acute/Early HIV Infection
G. Turk 1 , N. Laufer 2 , A.M. Rodriguez 1 , Y. Ghiglione 1 , J. Favilene 1 ,
M.J. Ruiz 1 , O. Sued 3 , L. Giavedoni 4 , P. Cahn 5 , H. Salomon 1 ,
M.M. Gherardi 1
1 Instituto de Investigaciones Biomédicas en Retrovirus y SIDA
INBIRS, Buenos Aires, Argentina; 2 Instituto de Investigaciones
Biomédicas en Retrovirus y SIDA INBIRS., Argentina; 3 Fundacion
Huesped, Buenos Aires, Argentina; 4 Southwest National
Primate Research Center, San Antonio, TX, USA; 5 Fundacion
Huesped/Hospital Juan A Fernandez, Buenos Aires, Argentina
Background: It is believed that initial encounter between HIV and
the human host triggers a complex series of events that dictate
future disease course. Inter-individual differences among the
host-players involved in these processes seem to early determine
different rates of disease progression. Here we were aimed at
studying the relationship between innate and adaptive soluble
immune mediators, HIV-specific T-cell response and the course
of acute infection.
Methods: Plasma levels of 37 cytokines were measured by
Luminex technology in different groups of volunteers: 10 healthy
donors (HD) and 50 HIV infected-subjects: 10 chronics, 12 aviremic
controllers (EC) and 28 subjects enrolled during acute infection
(AI). All HIV patients were off-HAART. Frozen PBMCs from the
same individuals were used to determine HIV-specific T-cell
responses by IFN-gamma ELISPOT. Data was compared inter- and
intra-groups and correlated to viral load (VL), CD4 T cell counts and
both virological (VL) and immunological (CD4 count) set-points (in
AI), using parametric and non-parametric statistics.
Results: Compared to HD, cytokines significantly elevated during
acute and chronic infection included IL-1alfa, IL-10, IP-10 and
TNF-alfa. Conversely, IL-12p40 and the macrophage-derived
chemokine (MDC) were only significantly elevated in chronics
and not in AI subjects who showed similar levels to HD and even
EC. Moreover, levels of IL-12p40, IL-12p70 and MDC directly
correlated with CD4 T-cell count among chronics and both CD4
T-cell count and immunological set point in AI. Regarding HIVspecific
T-cell response during AI, proportion of Gag-specific and
Nef-specific cells significantly correlated (directly and inversely,
respectively) with immunological set point
Conclusion: Both early and late components of the immune
system help preserve CD4 T-cell subset in HIV+ subjects: key
cytokines involved in the initiation and regulation of cellular
immune response and anti-Gag specificity of effector T-cells.
These features should be taken into account during vaccine
formulation design to boost favorable results.
228
AIDS Vaccine 2012
P11.24
Variable Processing and Presentation of HIV Epitopes
in Dendritic Cells and Macrophages to CD8 T Cells
P. Gourdain 1 , J. Dinter 1 , N. Lai 1 , M. Shimada 1 , E. Duong 1 ,
T. Zhu 1 , E. Bracho-Sanchez 1 , P. Liebesny 1 , S. Le Gall 1
1The Ragon Institute of MGH, MIT and Harvard, Charlestown,
MA, USA
Background: Whether HIV-infectable subsets, such as CD4 T
cells, monocytes, macrophages and dendritic cells (DCs), have
equivalent capacity to produce and present MHC-I restricted
epitopes to HIV-specific CD8 T cells is unknown. MHC-I epitopes
are processed by an intracellular degradation pathway involving
multiple proteases. In this study we analyzed the effect of
toll-like receptor (TLR) agonist-mediated maturation on the
processing and presentation of HIV antigens in monocytederived
DCs and macrophages.
Methods: Proteolytic activities were measured with a
fluorescence-based activity assay. Cytosolic extracts were used
as a source of peptidases to degrade extended epitopes in vitro.
Degradation products were then analyzed by mass spectrometry
and antigenicity was tested by a 51Cr release assay and a realtime
killing assay.
Results: Upon maturation with LPS or R848, the proteasomal and
lysosomal activities in matured macrophages are significantly
higher compared to matured DCs. The proteasomal tryptic and
caspase-like activities as well as the lysosomal activities decreased
approximately 1.5-fold in matured DCs. The degradation of
the N-terminal extended epitope 3-ISW9 in LPS-matured DCs
yielded 2-fold more optimal epitope ISW9 than in immature
DCs, which resulted in a 3-fold higher cell lysis in a 51Cr release
assay. In addition, the cross-presentation of exogenously added
p24 protein by DCs or macrophages showed reduced killing of
APCs by ISW9-specific CTLs compared to CTLs specific for TW10
or KF11. This lower ISW9-specific killing was partly rescued by
preincubation with protease inhibitor.
Conclusion: We showed that differences in antigen processing
activities in DCs and macrophages upon maturation, and
differences in HIV sequences sensitivity to intracellular
degradation may affect the production and presentation of
epitopes and thus the capacity of HIV-specific CTLs to recognize
and kill infected cells. For the design of a vaccine immunogen
it is critical to identify factors regulating the processing and
presentation of epitopes.
Supported by NIH NIAID R01 A1084753