Enhanced expression of miR-26a ameliorates lipopolysaccharide-induced endometritis by targeting MAP3K8 to inactivate MAPK signaling pathway

Expression profiling and single nucleotide polymorphism of mitogen-activated protein kinase kinase kinase 8 MAP3K8 in white muscovy ducks (Cairina moschata)

A previous study on ovarian and hypothalami transcriptome analysis in white Muscovy duck revealed that MAP3K8 gene participated in MAPK signaling pathway that influence egg production. Additionally, MAP3K8 was predicted as a target gene of miRNA-509-3p that promotes the secretion of oestradiol which is an important hormone in egg ovulation. This suggested that MAP3K8 might have a functional role in the reproductive performance "egg production" of white Muscovy ducks. Herein, we focused on expression level of MAP3K8 in reproductive and non-reproductive tissues of highest (HP) and lowest (LP) egg producing white Muscovy ducks and identified the polymorphism in MAP3K8 and its association with three egg production traits; Age at first egg (AFE), number of eggs at 300 days (N300D) and 59 weeks (N59W). The results of expression level indicated that mRNA of MAP3K8 was significantly (p < 0.01) expressed in the oviduct than in the ovary and hypothalamus. Seven synonymous SNPs were detected, and association analysis showed that g.148303340 G>A and g.148290065 A>G were significantly (p < 0.05) associated with N300D and N59W. The results of this study might serve as molecular marker for marker-assisted selection of white Muscovy ducks for egg production.

In Vitro Analysis of LPS-Induced miRNA Differences in Bovine Endometrial Cells and Study of Related Pathways

Lipopolysaccharide (LPS) is one of the main factors inducing endometritis in dairy cows. However, the specific pathogenesis of LPS-induced endometritis in dairy cows is not fully understood. The objective of this study was to establish an in vitro endometritis model using LPS-induced bovine endometrial epithelial (BEND) cells. BEND cells were treated with LPS of different concentrations and times. The cell-counting kit-8 (CCK-8) was used to detect the cell survival rate after LPS treatment, and quantitative real-time PCR (RT-qPCR) was used to detect the expression of control group and LPS-treated group of inflammatory factors interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNF-α). The results showed that the survival rate of endometrial epithelial cells stimulated by 5 μg/mL LPS for 6 h was 75.13%, and the expression of inflammatory factors was significantly increased. Therefore, 5 μg/mL LPS for 6 h could be selected as a suitable model for the study of inflammation. In addition, miRNA sequencing and target gene prediction was performed on normal and LPS-treated BEND cells. Among twenty-one differentially expressed miRNAs, six miRNAs were selected and their expression levels were detected by RT-qPCR, which were consistent with the sequencing results. Twenty-one differentially expressed miRNAs collectively predicted 17,050 target genes. This study provides a theoretical basis for further investigation of the pathogenesis of endometritis.

The bta-miR-22-3p can alleviate LPS-induced inflammatory response in yak endometrial epithelial cells by targeting KSR2

Bovine endometritis is a common reproductive system disease in dairy cows that leads to decreased milk production and reproductive performance, causing significant economic losses for farmers. Research has shown that microRNAs (miRNAs) play a significant role in regulating the expression of biological genes and are closely related to the occurrence of inflammation, including bta-miR-22-3p. However, the specific molecular mechanisms by which miRNAs regulate bovine endometritis remain unclear. To investigate the regulatory mechanism of bta-miR-22-3p in yak endometritis, uterine tissues were collected from three healthy bos grunniens and three bos grunniens with endometritis, approximately 21 days postpartum. Various methods were employed, including real-time quantitative polymerase chain reaction (RT-qPCR), Western blot (WB), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence (IF). The results demonstrated that overexpression of bta-miR-22-3p led to a significant decrease (P < 0.05) in factors related to the mitogen-activated protein kinase (MAPK) signaling pathway and associated inflammatory factors, such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (P38), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). Furthermore, dual-luciferase assays confirmed that the kinase suppressor of the Ras 2 (KSR2) gene is a downstream target of bta-miR-22-3p. Overexpression of bta-miR-22-3p inhibited the expression of KSR2. When KSR2 was inhibited, the levels of MAPK signaling pathway-related factors and inflammation also significantly decreased (P < 0.05). Thus, bta-miR-22-3p suppresses the activation of the MAPK signaling pathway through the inhibition of KSR2, resulting in a reduction of inflammatory factors. In conclusion, this study demonstrated that bta-miR-22-3p targets the KSR2 gene to alleviate LPS (Lipopolysaccharide)-induced inflammatory damage.

Up-regulation of inflammatory, oxidative stress, and apoptotic mediators via inflammatory, oxidative stress, and apoptosis-associated pathways in bovine endometritis

Endometritis is the inflammation of the endothelial lining of the uterine lumen and is multifactorial in etiology. Escherichia (E.) coli is a Gram-negative bacteria, generally considered as a primary causative agent for bovine endometritis. Bovine endometritis is characterized by the activation of Toll-like receptors (TLRs) by E. coli, which in turn triggers inflammation, oxidative stress, and apoptosis. The objective of this study was to investigate the gene expression of inflammatory, oxidative stress, and apoptotic markers related to endometritis in the uteri of cows. Twenty uterine tissues were collected from the abattoir. Histologically, congestion, edema, hyperemia, and hemorrhagic lesions with massive infiltration of neutrophil and cell necrosis were detected markedly (P < 0.05) in infected uterine samples. Additionally, we identify E. coli using the ybbW gene (177 base pairs; E. coli-specific gene) from infected uterine samples. Moreover, qPCR and western blot results indicated that TLR2, TLR4, proinflammatory mediators, and apoptosis-mediated genes upregulated except Bcl-2, which is antiapoptotic, and there were downregulations of oxidative stress-related genes in the infected uterine tissue. The results of our study suggested that different gene expression regimes related to the immune system reflex were activated in infected uteri. This research gives a novel understanding of active immunological response in bovine endometritis.