Impairment of microglial functions, such as phagocytosis and/or dysregulation of immune responses, has been implicated as an underlying factor involved in the pathogenesis of various neurodegenerative disorders. Our previous studies have demonstrated that long intergenic noncoding RNA (lincRNA)-Cox2 expression is influenced by nuclear factor κB (NF-κB) signaling and serves as a coactivator of transcriptional factors to regulate the expression of a vast array of immune-related genes in microglia. Extracellular vesicles (EVs) have been recognized as primary facilitators of cell-to-cell communication and cellular regulation. Herein, we show that EVs derived from astrocytes exposed to morphine can be taken up by microglial endosomes, leading, in turn, to activation of Toll-like receptor 7 (TLR7) with a subsequent upregulation of lincRNA-Cox2 expression, ultimately resulting in impaired microglial phagocytosis. This was further validated in vivo, wherein inhibition of microglial phagocytic activity was also observed in brain slices isolated from morphine-administrated mice compared with control mice. Additionally, we also showed that intranasal delivery of EVs containing lincRNA-Cox2 siRNA (small interfering RNA) was able to restore microglial phagocytic activity in mice administered morphine. These findings have ramifications for the development of EV-loaded RNA-based therapeutics for the treatment of various disorders involving functional impairment of microglia.

The objectives of this study were to lay the methodological groundwork for field studies of microRNA analysis in exosomes from small sample volumes of human milk, and assess exosome and microRNA content in infant formulas. When human milk was stored at 4°C for 4 weeks, the count of exosome-sized vesicles decreased progressively to 49% ± 13% of that in fresh milk. Exosomes were purified from 1 mL of fresh human milk and their microRNA content was assessed by microRNA-sequencing analysis and compared with that in infant formulas. We identified 221 microRNAs in exosomes from 3 samples of fresh human milk; 84 microRNAs were present in all 3 samples. MicroRNAs were not detectable in infant formulas and their exosome-sized vesicles, which appeared to be casein micelles. We conclude that large-scale studies of microRNAs in human milk exosomes are feasible, and exosomes and microRNAs are not detectable in formulas.

Exosomes are nanoparticles that transfer cargos from donor cells to recipient cells where they elicit changes in gene expression and metabolism. Evidence suggests that exosomes and their cargos are also absorbed from dietary sources such as bovine milk, and bovine exosomes promote the growth of myofibers in murine C2C12 myotube cell cultures. The aim of the current study was to determine whether the dietary intake of bovine milk exosomes alters strength, gene expression and amino acid profiles in murine skeletal muscles. Male and female C57BL/6 mice, age three weeks, were fed an AIN93G-based, exosome and RNA-depleted (ERD) diet for six weeks; controls were fed an exosome and RNA-sufficient (ERS) diet. Variables of feeding behavior, metabolism, grip strength, liver and kidney function, amino acid profiles, and gene expression patterns were analyzed by using metabolic cages, grip strength analyzers, clinical chemistry analyzers, targeted LC/MS-MS, and RNA sequencing analysis. The diets had no effect on food and water intake, respiratory exchange rate, physical activity, grip strength, markers of liver and kidney dysfunction, and amino acid profiles in muscle. Only twelve and nine mRNAs were differentially expressed in skeletal muscle from female and male mice, respectively, fed ERD and ERS diets. The modest effect of the ERD diet on gene expression and levels of free amino acids in skeletal muscle is consistent with observations that bovine milk exosomes and their cargos accumulate in tissues other than skeletal muscle.

MicroRNAs have been long considered synthesized endogenously until very recent discoveries showing that human can absorb dietary microRNAs from animal and plant origins while the mechanism remains unknown. Compelling evidences of microRNAs from rice, milk, and honeysuckle transported to human blood and tissues have created a high volume of interests in the fundamental questions that which and how exogenous microRNAs can be transferred into human circulation and possibly exert functions in humans. Here we present an integrated genomics and computational analysis to study the potential deciding features of transportable microRNAs. Specifically, we analyzed all publicly available microRNAs, a total of 34,612 from 194 species, with 1,102 features derived from the microRNA sequence and structure. Through in-depth bioinformatics analysis, 8 groups of discriminative features have been used to characterize human circulating microRNAs and infer the likelihood that a microRNA will get transferred into human circulation. For example, 345 dietary microRNAs have been predicted as highly transportable candidates where 117 of them have identical sequences with their homologs in human and 73 are known to be associated with exosomes. Through a milk feeding experiment, we have validated 9 cow-milk microRNAs in human plasma using microRNA-sequencing analysis, including the top ranked microRNAs such as bta-miR-487b, miR-181b, and miR-421. The implications in health-related processes have been illustrated in the functional analysis. This work demonstrates the data-driven computational analysis is highly promising to study novel molecular characteristics of transportable microRNAs while bypassing the complex mechanistic details.

We investigated the differential expression of circular RNAs (circRNAs) in plasma samples from three coronary artery disease (CAD) patients to identify putative therapeutic targets. We identified 24 differentially expressed circRNAs (18 up-regulated and 6 down-regulated) and 7 differentially expressed mRNAs (6 up-regulated and 1 down-regulated) in CAD patients based on competing endogenous RNA (ceRNA) microarray analysis. MiR-221(p = 0.001), miR-155(p = 0.049), and miR-130a (p = 0.001) were downregulated in CAD patients based on qRT-PCR analysis of another independent population of 932 study subjects (648 CAD subjects and 284 controls). We constructed a hsa-miR-130a-3p-mediated circRNA-mRNA ceRNA network using the miRanda database. This included 9 circRNAs (hsa_circ_0089378, hsa_circ_0083357, hsa_circ_0082824, hsa_circ_0068942, hsa_circ_0057576, hsa_circ_0054537, hsa_circ_0051172, hsa_circ_0032970, and hsa_circ_0006323) and 1 mRNA (transient receptor potential cation channel subfamily M member 3 [TRPM3]). We have shown that 9 circRNAs promote TRPM3 expression by inhibiting hsa-miR-130a-3p in CAD patients.