Summary Cellular lipid requirements are achieved through a combination of biosynthesis and import programs. Using isotope tracer analysis, we show that type I interferon (IFN) signaling shifts the balance of these programs by decreasing synthesis and increasing import of cholesterol and long chain fatty acids. Genetically enforcing this metabolic shift in macrophages is sufficient to render mice resistant to viral challenge, demonstrating the importance of reprogramming the balance of these two metabolic pathways in vivo. Unexpectedly, mechanistic studies reveal that limiting flux through the cholesterol biosynthetic pathway spontaneously engages a type I IFN response in a STING-dependent manner. The upregulation of type I IFNs was traced to a decrease in the pool size of synthesized cholesterol, and could be inhibited by replenishing cells with free cholesterol. Taken together, these studies delineate a metabolic-inflammatory circuit that links perturbations in cholesterol biosynthesis with activation of innate immunity.

In this review, we will discuss what is known, what is suspected, and what still remains obscure about the central role played by coreceptor expression and usage in the transmission and pathogenic consequences of human immunodeficiency virus type 1 (HIV-1) infection. An emphasis will be on the HIV-1 phenotypic variants that are defined by their usage of the CCR5 or CXCR4 coreceptors, and how the different cellular tropism of these variants influences how and where HIV-1 replicates in vivo. We will also review what might happen when coreceptor antagonists are used clinically to treat HIV-1 infection.

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The human immunodeficiency virus (HIV)-specific cytotoxic T lymphocyte (CTL) response is critical in controlling HIV infection. Since the immune response does not eliminate HIV, it would be beneficial to develop ways to enhance the HIV-specific CTL response to allow long-term viral suppression or clearance. Here, we report the use of a protective chimeric antigen receptor (CAR) in a hematopoietic stem/progenitor cell (HSPC)-based approach to engineer HIV immunity. We determined that CAR-modified HSPCs differentiate into functional T cells as well as natural killer (NK) cells in vivo in humanized mice and these cells are resistant to HIV infection and suppress HIV replication. These results strongly suggest that stem cell-based gene therapy with a CAR may be feasible and effective in treating chronic HIV infection and other morbidities.