Innate cytokines associate with exosomes in plasma of HIV-1+ individuals (P6205)

Abstract

Abstract Purpose: Our group and others have demonstrated a potential role for exosomes in HIV pathogenesis. Exosomes secreted from HIV-infected cells were shown to contain coreceptors for HIV. We have shown HIV Nef-containing exosomes from HIV-infected cells induced apoptosis in bystander CD4+ T cells. This suggests that exosomes from HIV-infected cells could drive CD4 depletion and immune activation contributing to HIV pathogenesis. Thus, exosomes from HIV-1+ viremic individuals were investigated for protein content. Methods: Exosomes were isolated from plasma of ARV naïve, HIV+ and negative control individuals by differential centrifugation followed by iodixanol density gradient ultracentrifugation. Biochemical characterization included AChE activity, flotation in iodixanol gradients, and Western analysis for exosomal markers. Plasma and purified exosomes were also tested for levels of 30 cytokines and chemokines by multiplex assay. Results: The concentrations of 10 innate cytokines (IL-15, IP-10, FasL, CD40L, IFNα, IFNβ, MIP-1α, MIP-1β, TNFα, and ICAM-1) were found to be associated with and significantly elevated in exosomes from HIV+ individuals relative to negative controls, suggesting a contributing role in generalized chronic immune inflammation. Conclusion: This is the first demonstration of innate cytokines in exosomes of HIV+ individuals. It suggests a potential mechanism for HIV-1 driven immune modulation and propagation of HIV via activation of bystander target cells.