Potent Cell-Intrinsic Immune Responses in Dendritic Cells Facilitate HIV-1-Specific T Cell Immunity in HIV-1 Elite Controllers

Abstract

The majority of HIV-1 elite controllers (EC) restrict HIV-1 replication through highly functional HIV-1-specific T cell responses, but mechanisms supporting the evolution of effective HIV-1-specific T cell immunity in these patients remain undefined. Cytosolic immune recognition of HIV-1 in conventional dendritic cells (cDC) can facilitate priming and expansion of HIV-1-specific T cells; however, HIV-1 seems to be able to avoid intracellular immune recognition in cDCs in most infected individuals. Here, we show that exposure of cDCs from EC to HIV-1 leads to a rapid and sustained production of type I interferons and upregulation of several interferon-stimulated effector genes. Emergence of these cell-intrinsic immune responses was associated with a reduced induction of SAMHD1 and LEDGF/p75, and an accumulation of viral reverse transcripts, but inhibited by pharmacological blockade of viral reverse transcription or siRNA-mediated silencing of the cytosolic DNA sensor cGAS. Importantly, improved cell-intrinsic immune recognition of HIV-1 in cDCs from elite controllers translated into stronger abilities to stimulate and expand HIV-1-specific CD8 T cell responses. These data suggest an important role of cell-intrinsic type I interferon secretion in dendritic cells for the induction of effective HIV-1-specific CD8 T cells, and may be helpful for eliciting functional T cell immunity against HIV-1 for preventative or therapeutic clinical purposes.

Author Summary

Elite controllers (EC), a small group of HIV-1-infected individuals that are able to control viral replication in the absence of antiretroviral therapy, provide living evidence that the human immune system is able to spontaneously control HIV-1 infection and serve as a model for inducing a functional cure of HIV-1 infection in broader patient populations. Prior studies indicated that T cell-mediated immune responses represent the backbone of effective antiviral immune defense in EC; however, emerging studies suggest that innate and cell-intrinsic immune activities may have critical roles for supporting and enhancing HIV-1-specific T cells. Here, we performed a detailed investigation of conventional dendritic cells (cDC) from elite controllers and their responses to HIV-1 infection. These studies indicate that cDC from EC have improved abilities to sense cytosolic HIV-1 replication products, and can more effectively mount cell-intrinsic type I interferon (IFN) secretion in response to HIV-1 infection. Notably, such increased production of type I IFN in response to viral antigen translated into enhanced abilities to prime and expand HIV-1-specific T cells. Together, these data suggest that a fine-tuned interplay between innate dendritic cell responses and adaptive HIV-1-specific CD8 T cells represents a critical component of antiviral immune defense in elite controllers.