GABA-induced monocytic reactive oxygen species impair CD4 restoration in treated HIV-1 adults

Background In order to better understand why about 15% of people living with Human Immunodeficiency Virus-1 (PWH) on highly active antiretroviral therapy do not restore their CD4 count, we explored the link previously reported between glutamate plasma level and CD4 count. Methods We recruited fourty-four adults living with HIV-1 aviremic under antiretroviral therapy. Their peripheral blood concentrations in glutamate and GABA were determined by ELISA. Flow cytometry was used to detect GABA receptor, reactive oxygen species (ROS) produced by monocytes, and programmed T cell death. DNA-dependent protein kinase (DNA-PK) and p53 phosphorylation were analyzed by western blot. DNA damage was quantified by immunofluorescence. Results We show that i) some virologic responders present high plasma levels of glutamate and of its derivative, GABA; ii) monocytes express the GABA receptor GABA-B1; iii) GABA-B1 stimulation induces monocytic ROS production; iv) GABA-B1-overexpressing monocytes of PWH with high plasma levels of GABA release high amount of ROS; and v) monocyte-derived ROS oxidise the DNA of CD4+ T cells, creating double-strand breaks which activate DNA-PK and p53, and finally apoptosis. The intensity of this cascade of events is inversely correlated with the slope of CD4+ T cell recovery in treated PWH. Discussion We propose that DNA damage resulting from ROS produced by GABA-activated monocytes plays a key role in impaired immune restoration. Consequently, GABA-B1 antagonists and/or ROS inhibitors might be a promising therapy for non-immunologic responders. Furthermore, the same mechanism could be involved in CD4 loss in the natural course of the infection.