Human breast milk has been shown to reduce the incidence of necrotizing enterocolitis (NEC). Breast milk has many components (immunoglobulins, proteins, fat, and, of recent interest, exosomes), but the specific component that affords protection against NEC is not known. Exosomes are small-nanometer vesicles that are rich in protein, lipid, and microRNA. Here, we hypothesized that human breast milk-derived exosomes can protect intestinal epithelial cells (IECs) from cell death. Human breast milk was collected, separated using ultracentrifugation, and quantified using NanoSight tracking analysis. Purified exosomes were added to IECs that had been treated with varying concentrations of HO. Cells were then incubated overnight with the human breast milk-derived exosomes and assessed for cell viability. Western blot analysis showed that both clathrin and CD81 were present in the purified sample. Oxidative stress using HO caused a 50% decrease in cell viability and human breast milk-derived exosomes had a protective effect in IECs. In the presence of HO, exosomes had a statistically significant protective effect. The protection seen by human breast milk-derived exosomes was not attenuated by cycloheximide. Thus, human breast milk-derived exosomes allow IECs to be protected from oxidative stress, but the mechanism is still not clear. Exosomes derived from human breast milk are an attractive treatment concept for children with intestinal injury.

Exosomes, 30–200 nm nanostructures secreted from donor cells and internalized by recipient cells, can play an important role in the cellular entry of some viruses. These microvesicles are actively secreted into various body fluids, including blood, urine, saliva, cerebrospinal fluid, and breast milk. We successfully isolated exosomes from human breast milk and plasma. The size and concentration of purified exosomes were measured by nanoparticle tracking, while Western blotting confirmed the presence of the exosomal-associated proteins CD9 and CD63, clathrin, and T cell immunoglobulin and mucin proteins (TIMs). Through viral infection assays, we determined that HIV-1 utilizes an exosome-dependent mechanism for entry into human immune cells. The virus contains high amounts of phosphatidylserine (PtdSer) and may bind PtdSer receptors, such as TIMs. This mechanism is supported by our findings that exosomes from multiple sources increased HIV-1 entry into T cells and macrophages, and viral entry was potently blocked with anti-TIM-4 antibodies.

HIV-1 is one of the most studied retroviruses. The role of exosomes in HIV-1 entry and pathogenesis are beginning to be appreciated. Exosomes can incorporate host proteins that are also contained in viruses (e.g., tetraspanins).

Exosomes are small extracellular vesicles that have emerged as an important tool for intercellular communication. In the central nervous system, exosomes can mediate glia and neuronal communication. Once released from the donor cell, exosomes can act as discrete vesicles and travel to distant and proximal recipient cells to alter cellular function. Microglia cells secrete exosomes due to stress stimuli of alcohol abuse. The goal of this study was to investigate the effects of alcohol exposure on the biogenesis and composition of exosomes derived from microglia cell line BV-2. The BV-2 cells were cultured in exosome-free media and were either mock treated (control) or treated with 50 mM or 100 mM of alcohol for 48 and 72 h. Our results demonstrated that alcohol significantly impacted BV-2 cell morphology, viability, and protein content. Most importantly, our studies revealed that exosome biogenesis and composition was affected by alcohol treatment.

Cocaine is a highly addictive stimulant and a well-known drug, with multiple effects on physiology. Cocaine can have direct effects on all cell types in the brain, including microglia. Microglia can be activated by other conditions, such as infection, inflammation, or injury. However, how cocaine regulates microglia and the influence of cocaine on microglial-derived exosomes remains unknown. Exosomes are nanovesicles that are responsible for intercellular communications, signaling, and trafficking necessary cargo for cell homeostasis. In this study, we hypothesized that cocaine affects exosome biogenesis and composition in BV2 microglial cells. BV2 microglial cells were cultured in exosome-depleted RPMI-1640 media and were treated according to the experimental designs. We observed that cell viability decreased by 11% at 100 µM cocaine treatment but was unaffected at other concentrations. After treatments, the exosomes were isolated from the condition media. Purified exosomes were characterized and quantified using transmission electron microscope (TEM) and nanoparticle tracking analysis (NTA). By NTA, there was a significant decrease in particles/mL after cocaine treatment. There was a 39.5%, 58.1%, 32.3% and 28.1% decrease in particles/mL at 100 nM, 1 μM, 10 μM and 100 μM cocaine, respectively. The characterization of exosomes and exosomal protein was performed by western/dot blot analyses. Tetraspanins CD11b, CD18 and CD63 were relatively unchanged after cocaine treatment. The heat shock proteins (Hsps), Hsp70 and Hsp90, were both significantly increased at 10 μM and 100 μM, but only hsp70 was significantly increased at 10 nM. The Rab proteins were assessed to investigate their role in cocaine-mediated exosomal decrease. Rab11 was significantly decreased at 10 nM, 100 nM, 1 μM, 10 μM and 100 μM by 15%, 28%, 25%, 38% and 22%, respectively. Rab27 was decreased at all concentrations but only significantly decreased at 100 nM, 1 μM and 100 μM cocaine by 21%, 24% and 23%, respectively. Rab35 had no significant changes noted when compared to control. Rab7 increased at all cocaine concentrations but only a significant increase in expression at 100 nM and 10 μM by 1.32-fold and 1.4-fold increase. Cocaine was found to alter exosome biogenesis and composition in BV2 microglial cells. Western and dot blot analyses verified the identities of purified exosomes, and the specific protein compositions of exosomes were found to change in the presence of cocaine. Furthermore, cocaine exposure modulated the expression of exosomal proteins, such as Hsps and Rab GTPases, suggesting the protein composition and formation of microglial-derived exosomes were regulated by cocaine.