Influence of HLA-C environment on the spontaneous clearance of hepatitis
C in European HIV-HCV co-infected individuals
Abstract
Natural Killer (NK) cell functions are regulated by diverse inhibitory
and activating receptors including Killer cell Immunoglobulin-like
receptors (KIR) which interact with HLA class I molecules. Some KIR/HLA
genetic combinations were reported associated with spontaneous clearance
(SC) of hepatitis C virus (HCV) but with discordant results, possibly
reflecting KIR and/or HLA gene polymorphism according to populations.
KIR/HLA genetic combinations associated with both an exhaustive NK and T
cell repertoire were investigated in a cohort of HIV-HCV co-infected
individuals with either SC (n=68) or chronic infection (CI, n=163)
compared to uninfected blood donors (Ctrl, n=100). Multivariate analysis
showed that the HLA C2C2 environment was associated with SC only in
European HIV-HCV co-infected individuals (OR=4.30[1.57-12.25],
p=0.005). KIR2D+ NK cell repertoire and potential of degranulation of
KIR2DL1/S1+ NK cells were similar in SC European cohort compared to
uninfected individuals. In contrast, decreased frequencies of KIR2DS1+
and KIR2DL2+ NK cells were detected in CI group of Europeans compared to
SC and a decreased frequency of KIR2DL1/S1+ NK cells compared to
controls. On the T cell side, higher frequencies of DNAM-1+ and CD57+ T
cells were observed in SC in comparison to controls. Interestingly, SC
subjects emphasized increased frequencies of KIR2DL2/L3/S2+ T cells
compared to CI subjects. Our study underlines that the C2 environment
may activate efficient KIR2DL1+ NK cells in viral context and maintain
KIR2DL2/L3/S2+ mature T cell response in the absence of KIR2DL2
engagement with its cognate ligands in SC group of HCV-HIV co-infected
European patients.