Summary As an inflammation of the endometrium, endometritis can affect fertility and lead to serious economic losses in the dairy industry. Widely found in various tissues and body fluids, exosomes and exosome micro (mi)RNAs have been shown to play an important regulatory role in the immune responses. As one of differentially expressed exosome miRNAs, miR‐218 is involved in the pathogenesis of bovine endometritis. The mechanisms of miR‐218 in regulating the release of cytokines and chemokines in endometritis, however, are poorly understood. Exosomes were isolated from bovine uterine cavity fluid and verified by transmission electron microscopy. An in vitro lipopolysaccharide‐treated cell model for bovine endometritis was then established to evaluate the correlation between exosome‐derived miR‐218 and the immune responses. We demonstrated that exosomes could be used to deliver miR‐218 from endometrial epithelial cells (EECs) into the uterine microenvironment and adjacent recipient cells to modulate local immune responses. miR‐218 packaged in the exosomes secreted from EECs acts as an inhibitor by blocking immune factors such as interleukin (IL)‐6, IL‐1β, tumour necrosis factor‐α, the chemokines macrophage inflammatory genes (MIP)‐1α and MIP‐1β to maintain the immune balance in the uterus. However, uterine inflammation altered the immunoregulatory mechanism of exosome miR‐218. MiR‐218 is a potential biomarker for the detection of endometritis. Our findings also revealed a new mechanism for the development of endometritis in cows.

Endometritis is a common disease affecting fertility in cows during the perinatal period, which disturbs the molecular milieu of the uterine environment and impairs embryo development and implantation. Exosomes are important extracellular components that transmit a variety of micro RNAs (miRNAs), which perform key regulatory functions. In this study, we investigated plasma exosomal miRNAs from cows with endometritis and from cultured endometrial epithelial cells (EECs) challenged with lipopolysaccharide (LPS) to explore the role of EEC-derived exosomes and their miRNAs in bovine endometritis. Plasma exosomes were collected from nine healthy dairy cows and nine dairy cows with endometritis, and culture supernatant exosomes were isolated from EECs challenged with or without LPS. Exosomal RNA was extracted using commercial kits and miRNA profiles were generated using RNA-seq. We found that miR-218 was differentially expressed in EECs under conditions of endometrial inflammation. Inhibition studies suggested that reduced levels of miR-218 in EEC-derived exosomes when transferred into placental trophoblast cells impaired embryonic development and decreased placental trophoblast cell migration by targeting secreted frizzled related protein 2. We propose that exosomal miR-218 secreted from EECs acts as a driver of embryonic development and differentiation. In addition, exosomal miR-218 may provide a valuable diagnostic marker for bovine endometritis.

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The WD40 transcription factor (TF) family is widespread in plants and plays important roles in plant growth and development, transcriptional regulation, and tolerance to abiotic stresses. WD40 TFs have been identified and characterized in a diverse series of plant species. However, little information is available on WD40 genes from D. longan. In this study, a total of 45 DlWD40 genes were identified from D. longan RNA-Seq data, and further analysed by bioinformatics tools. Also, the expression patterns of DlWD40 genes in roots and leaves, as well as responses to heat stress, were evaluated using quantitative real-time PCR (qRT-PCR). We found that the 45 DlWD40 proteins, together with 80 WD40 proteins from Arabidopsis and Zea mays, could be categorized into six groups. Of these, the DlWD40-4 protein was highly homologous to Arabidopsis WDR5a, a protein participating in tolerance to abiotic stresses. Moreover, a total of 25 cis-acting elements, such as abiotic stress and flavonoid biosynthesis elements, were found in the promoters of DlWD40 genes. The DlWD40-33 gene is targeted by miR3627, which has been proposed to be involved in flavonoid biosynthesis. Using qRT-PCR, ten of the 45 DlWD40 genes were demonstrated to have diverse expression patterns between roots and leaves, and these ten DlWD40 genes could also respond to varying durations of a 38 °C heat stress in roots and leaves. The results reported here will provide a basis for the further functional verification of DlWD40 genes in D. longan.