The Effect of Selenium on Endometrial Repair in Goats with Endometritis at High Cortisol Levels

Selenium Yeast Alleviates Escherichia coli-Induced Endometritis in Goats Under High Cortisol Background

During the postpartum period, domestic ruminants suffer elevated endogenous cortisol levels, which are associated with an increased risk of uterine infections. Selenium is a trace mineral nutrient with beneficial impacts on animals. The study aimed to investigate whether selenium yeast (SeY) could attenuate Escherichia coli (E. coli)-induced endometrial injury in goats with high cortisol background. Goats were examined after oral SeY administration for 21 days and were treated with glacial acetic acid, E. coli, and hydrocortisone to establish an endometritis model with high cortisol background. The results showed that endometrial injury caused by E. coli was aggravated under high cortisol background. Supplementation with SeY alleviated endometrial inflammation and serum LDH content. The mRNA expression of pro-inflammatory cytokines and defensin beta 2 and the phosphorylation level of the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-b (NF-κB) signaling pathways were decreased by SeY supplementation. Total antioxidant capacity and antioxidant enzymes activities were increased by SeY supplementation, but malondialdehyde and 4-hydroxynonenal content were decreased. Moreover, nuclear factor erythroid-2 related factor 2 (NRF2) in the nucleus, heme oxygenase-1, and NAD(P)H quinone dehydrogenase 1 were increased by SeY supplementation. So, supplementation with SeY alleviated E. coli-induced endometritis in goats by activating the NRF2 pathway and inhibiting the activation of the MAPK and NF-κB pathways under postpartum stress.

Selenium elicited an enhanced anti-inflammatory effect in primary bovine endometrial stromal cells with high cortisol background

BACKGROUND

An elevated endogenous cortisol level due to the peripartum stress is one of the risk factors of postpartum bovine uterine infections. Selenium is a trace element that elicits anti-inflammation and antioxidation properties. This study aimed to reveal the modulatory effect of selenium on the inflammatory response of primary bovine endometrial stromal cells in the presence of high-level cortisol. The cells were subjected to lipopolysaccharide to establish cellular inflammation. The mRNA expression of toll-like receptor 4 (TLR4), proinflammatory factors, and selenoproteins was measured with qPCR. The activation of NF-κB and MAPK signalling pathways was detected with Western blot and immunofluorescence.

RESULTS

The pretreatment with sodium selenite (2 and 4 µΜ) resulted in a down-regulation of TLR4 and genes encoding proinflammatory factors, including interleukin (IL)-1β, IL-6, IL-8, tumour necrosis factor α, cyclooxygenase 2, and inducible nitric oxide synthase. Selenium inhibited the activation of NF-κB and the phosphorylation of mitogen-activated protein kinase kinase, extracellular signal-regulated kinase, p38MAPK and c-Jun N-terminal kinase/stress-activated protein kinase. The suppression of those genes and pathways by selenium was more significant in the presence of high cortisol level (30 ng/mL). Meanwhile the gene expression of glutathione peroxidase 1 and 4 was promoted by selenium, and was even higher in the presence of cortisol and selenium.

CONCLUSIONS

The anti-inflammatory action of selenium is probably mediated through NF-κB and MAPK, and is augmented by cortisol in primary bovine endometrial stromal cells.

The disordered extracellular matrix landscape induced endometrial fibrosis of sheep: A multi-omics integrative analysis

Endometrial fibrosis leads to the destruction of endometrial function and affects reproductive performance. However, mechanisms underlying the development of endometrial fibrosis in sheep remain unclear. We use transcriptomic, proteomic, and metabolomic studies to reveal the formation mechanisms of endometrial fibrosis. The results showed that the fibrotic endometrial tissue phenotype presented fewer glands, accompanied by collagen deposition. Transcriptomic results indicated alterations in genes associated with the synthesis and degradation of extracellular matrix components, which alter metabolite homeostasis, especially in glycerophospholipid metabolism. Moreover, differentially expressed metabolites may play regulatory roles in key metabolic processes during fibrogenesis, including protein digestion and absorption, and amino acid synthesis. Affected by the aberrant genes, protein levels related to the extracellular matrix components were altered. In addition, based on Kyoto Encyclopedia of Genes and Genomes analysis of differentially expressed genes, metabolites and proteins, amino acid biosynthesis, glutathione, glycerophospholipid, arginine and proline metabolism, and cell adhesion are closely associated with fibrogenesis. Finally, we analyzed the dynamic changes in serum differential metabolites at different time points during fibrosis. Taken together, fibrosis development is related to metabolic obstacles in extracellular matrix synthesis and degradation triggered by disturbed gene and protein levels.

The effect and mechanism of selenium supplementation on the proliferation capacity of bovine endometrial epithelial cells exposed to lipopolysaccharide in vitro under high cortisol background

Bovine endometritis severely inhibits uterine repair and causes considerable economic loss. Besides, parturition-induced high cortisol levels inhibit immune function, reduce cell proliferation, and further inhibit tissue repair. Selenium (Se) is an essential trace element for animals to maintain normal physiological function and has powerful antioxidant functions. This study investigated whether Se supplementation reduces endometrial damage and promotes tissue repair in cows with endometritis under stress and explored the underlying mechanism. Primary bovine endometrial epithelial cells were isolated and purified from healthy cows. The cells were treated with different combinations of lipopolysaccharide (LPS), cortisol, and various concentrations of Se. Data showed that LPS stimulation inhibited cell proliferation and increased cell apoptosis. High levels of cortisol further exacerbated these effects. Flow cytometry, scratch wound healing tests, and 5-ethynyl-2'-deoxyuridine (EdU) proliferation assays showed that Se supplementation promoted cell cycle progression, cell migration, and cell proliferation in the presence of LPS and cortisol. The quantitative PCR results showed that the expression of related growth factors was increased after Se supplementation. After administering various inhibitors, we further demonstrated that Se supplementation decreased the activity of glycogen synthetase kinase 3β (GSK-3β) through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway to reduce the degradation of β-catenin except the Wnt signal to promote cell proliferation. In conclusion, Se supplementation attenuated the cell damage induced by LPS at high cortisol levels and increased cell proliferation to promote uterine repair by elevating the mRNA expression of TGFB3 and VEGFA and activating the PI3K/AKT/GSK-3β/β-catenin signaling pathway.