HIV specific B-cell memory persists in seronegative early treated children and is dominated by IgM-memory responses
Authors: Cotugno N, Morrocchi E, Pepponi I, et al.
Abstract Early initiation of ART in HIV vertically infected infants influences specific immunity by limiting Ag exposure and reducing the viral reservoir size. Currently these patients represent ideal candidates for testing immune therapeutic strategies towards HIV-remission. However a proportion of these early ART treated children (ET) show an undetectable HIV Ab response. It is still unknown whether such profile is associated with a lower ability of these children to mount HIV specific responses once the Ag is re-encountered.
In the present study, we investigated whether HIV specific B-cells persist in seronegative (SN) patients, and the associated gene signatures after re-encountering the virus in vitro. We enrolled 20 ET (6 SN and 14 seropositive, SP), who initiated ART at a mean age of 4.4±3.6 mo. and under durable viral control (> 2 years). We found that gp140+ B-cells, analyzed by FACS, persist in SN patients with a similar frequency of SP. Further analysis revealed a higher percentage of HIV-specific IgM cells in SN CD27+ IgD+ memory subset compared to SP (P=0.002). In addition we investigated by multiplexed RT-PCR, gene expression dynamics after in vitro stimulation with HIV peptides mix. Our results on sorted HIV specific IgM+ cells showed up-regulation of Blimp1 expression only in SP (fold change=1.9; p=0.03), suggesting an impairment of plasma cell differentiation in IgM+gp140+ B-cells in SN patients. Our results firstly reveal that HIV specific B-cell response persists in SN ET, and predominantly resides in the IgM memory compartment. We hypothesize that such responses could be targeted by novel strategies aiming at HIV remission in HIV early treated children.