Plasma circulating extracellular vesicles reveal dysregulation of synaptic signaling in SHIV-infected rhesus macaque

Antiretroviral therapy suppresses human immunodeficiency virus (HIV) replication; however, nearly 50% of HIV infected patients suffer from HIV-associated neurocognitive disorders (HAND). Recently, we reported that proteins in plasma circulating extracellular vesicles (EVs) of either simian human immunodeficiency virus (SHIV) infected rhesus macaques (RMs) or HIV-infected patients show a link to neuropathogenesis. In this study, we show that proteins in circulating EVs of SHIV-infected RMs (SHIV-EVs) were associated with dysregulation of the synaptic signaling pathway. Plasma circulating EVs were isolated from SHIV-infected (SHIV-EVs) and uninfected (CTL-EVs) RMs and characterized by the ZetaView analyzer (n = 5/group) and transmission electron microscopy. Several EV-associated markers were detected by western blotting. Proteomic analysis of the isolated EVs (n = 3/group) was performed using liquid chromatography/mass spectrometry. Using ingenuity pathway analysis (IPA), the differentially expressed proteins (DEPs) involved in the dysregulation of different synaptic signaling pathways were assessed. Interestingly, proteins in SHIV-EVs were involved in synaptogenesis signaling deactivation, synaptic long-term potentiation/depression, and glutamate receptor signaling, as well as activation of semaphorin neuronal repulsive signaling pathways. Intriguingly, we observed that several proteins, which are involved in synaptic vesicle (SV) assembly and SV fusion, were abundantly under-expressed in SHIV-EVs compared with EVs of uninfected RMs. Dysregulated proteins in SHIV-EVs show possible deactivation of (a) SV priming, docking, and fusion in presynaptic neurons; and (b) synaptic spine development/density and synapse stabilization in postsynaptic neurons. Conversely, the activation of semaphorin neuronal repulsive signaling pathway in SHIV-EVs showed possible activation of cytoskeleton contraction/rearrangement, microtubule stabilization, and action repulsion, as well as deactivation of microtubule polymerization and action generation/outgrowth in SHIV-infected RMs. Dysregulated synaptic signaling-related proteins in SHIV-EVs were involved in several neuropathology-related disorders/diseases, including early/progressive neurological disorder, cognitive impairment, degenerative dementia, and Alzheimer’s disease. Our novel findings suggest that plasma circulating EVs can be a useful noninvasive technique to elucidate the mechanisms involved in the development of central nervous system dysfunction and the progression of neurological diseases such as HAND.