The Effects of HTLV-1 Extracellular Vesicle Subpopulations in Driving Autonomous Pro-Survival Signaling Across Infected and Uninfected T-Cell Subsets

Abstract

Human T-Cell Lymphotropic Virus Type-1 (HTLV-1) is an endemic retrovirus that causes various types of diseases, including adult T-cell leukemia. HTLV-1 is known to use extracellular vesicles (EVs), which are biological membrane packages that the infected cell releases, to transfer viral and cellular cargo into neighboring immune cells. Previous data have shown that HTLV-1 EVs stimulate pro-survival pathways of host cells; however, these studies have been conducted in HTLV-1-infected recipient T cells (HUT-102), which already have endogenously produced viral proteins such as Tax as well as increased levels of signaling. In order to investigate the independent effects of the EVs, we compared the signaling response in HTLV-1-infected recipient T cells (HUT-102) treated with EVs derived from infected cells versus uninfected control cells (CEM). For this purpose, we isolated five different types of EVs from the supernatant of infected (HUT-102) and uninfected (CEM) donor cells using differential centrifugation: 2K and 10K fractions (large EVs and microvesicles derived from the plasma membrane), 100K fractions (small EVs and exosomes originating from endosomes), and 167K 4-hour and 16-hour fractions (ultra-small EVs and exomeres derived with extended spinning time). HTLV-1-infected recipient cells (HUT-102) were treated with these vesicle populations according to standard procedures, after which their lysate was obtained and assessed through Western blot for the detection of targeted signaling proteins: specifically, those responsible for pro-survival, proliferation, and apoptosis (p-AKT, AKT, p-ERK, ERK, Survivin, BCL-XL, BAX), together with Actin loading control. This way we can identify which of these survival pathways are changed by specific types of vesicles. The latest Western blot results evaluating these key signaling proteins (p-AKT, AKT, p-ERK, ERK, Survivin, BCL-XL, BAX) will be presented on the poster and discussed in detail.