Purpose of review: Natural killer (NK) cells promote antiviral immunity by producing proinflammatory cytokines and by lysing infected cells. In addition, NK cells can modulate dendritic cell functions. NK–dendritic cell crosstalk results in activation of both cell types, with dendritic cells promoting NK-cell activity and NK cells inducing further maturation of dendritic cells. Here we review the recent evidence suggesting that NK–dendritic cell crosstalk is disrupted during HIV-1 infection and we discuss the consequences on HIV persistence in dendritic cells.
Recent findings: NK cell-mediated dendritic cell editing is compromised during HIV-1 infection, and NK cells from viremic individuals show a decreased ability to kill immature dendritic cells. The defect is associated with impaired NKp30 function. Moreover, the resistance of HIV-1-infected dendritic cells to NK-mediated lysis is associated with the upregulation of apoptosis inhibitors, thus protecting infected dendritic cells from TRAIL-dependent apoptosis. These inhibitors are upregulated by the high-mobility group box 1 protein (HMGB1), an alarmin produced at NK–dendritic cell synapse that is essential for NK-dependent dendritic cell maturation, but also promotes viral replication in infected dendritic cells.
Summary: HIV-1-induced impairment of NK–dendritic cell crosstalk may significantly alter both innate and adaptive immunity. It may also contribute to HIV persistence in dendritic cells through an HMGB1-dependent mechanism.