Collagen and Microvascularization in Placentas From Young and Older Mares

Quantitative proteomics reveals pregnancy prognosis signature of polycystic ovary syndrome women based on machine learning

OBJECTIVE

We aimed to screen and construct a predictive model for pregnancy loss in polycystic ovary syndrome (PCOS) patients through machine learning methods.

METHODS

We obtained the endometrial samples from 33 PCOS patients and 7 healthy controls at the Reproductive Center of the Second Hospital of Lanzhou University from September 2019 to September 2020. Liquid chromatography tandem mass spectrometry (LCMS/MS) was conducted to identify the differentially expressed proteins (DEPs) of the two groups. Gene Ontology (GO) as well as Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed to analyze the related pathways and functions of the DEPs. Then, we used machine learning methods to screen the feature proteins. Multivariate Cox regression analysis was also conducted to establish the prognostic models. The performance of the prognostic model was then evaluated by the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA). In addition, the Bootstrap method was conducted to verify the generalization ability of the model. Finally, linear correlation analysis was performed to figure out the correlation between the feature proteins and clinical data.

RESULTS

Four hundred and fifty DEPs in PCOS and controls were screened out, and we obtained some pathways and functions. A prognostic model for the pregnancy loss of PCOS was established, which has good discrimination and generalization ability based on two feature proteins (TIA1, COL5A1). Strong correlation between clinical data and proteins were identified to predict the reproductive outcome in PCOS.

CONCLUSION

The model based on the TIA1 and COL5A1 protein could effectively predict the occurrence of pregnancy loss in PCOS patients and provide a good theoretical foundation for subsequent research.

Low progesterone concentration in early pregnancy is detrimental to conceptus development and pregnancy outcome in horses

High progesterone concentrations in the early luteal phase support pregnancy, whereas subphysiological progesterone concentrations delay embryonic development at least until placentation. In this study, fetal growth and development of pregnancy was investigated in pregnancies with prostaglandin F2α-induced low progesterone concentrations (PGF) in the early luteal phase and control pregnancies (CON) in the same mares (n = 12). Mares were inseminated and in PGF pregnancies received the prostaglandin F2α analogue cloprostenol (62.5 µg) on days 0-3 after ovulation to induce subphysiological progesterone concentrations; CON pregnancies remained untreated. Mares were assigned to PGF or CON treatments in alternating order and received the opposite treatment in the following year. Blood was collected and conceptus size determined repeatedly by transrectal (≤day 101) and transabdominal (>day 101) ultrasonography. After birth, foals were weighed, measured and submitted to a clinical examination. Treatment PGF resulted in fewer pregnancies than CON treatment. All foals born from CON pregnancies were healthy and mature, whereas 4/7 PGF pregnancies were either lost (one embryonic death, one abortion) or resulted in the birth of compromised foals (P = 0.018). Size of the conceptus (e.g., diameter day 49: PGF 6.6 ± 0.7, CON 7.7 ± 0.7 cm, P = 0.006) and embryo proper (e.g., crown rump length day 54; PGF 4.4 ± 0.8, CON 5.8 ± 0.6 cm, P = 0.015) differed between treatments. These size differences decreased over time and at birth PGF foals did not differ significantly from CON foals. In conclusion, reduced progesterone concentration in the early luteal phase leads to delayed conceptus growth beyond placentation and increased pregnancy loss.

Collagen Type III as a Possible Blood Biomarker of Fibrosis in Equine Endometrium

Simple Summary

In the mare, endometrosis is a disease characterized by excessive collagen fibers deposition in the endometrium (uterus inner layer), which is responsible for infertility. The gold standard method for endometrosis evaluation has been endometrial biopsy histopathological classification. The use of blood biomarkers for endometrosis identification would be less invasive, and could provide additional information regarding endometrosis diagnosis and fertility prognosis. Therefore, this study aimed to identify possible blood biomarkers for endometrosis diagnosis and fertility assessment on mares. Reproductive examination, endometrial biopsy histopathological classification, and blood collection were performed. Endometrium and serum collagen type I (COL1) and type III (COL3), and hydroxyproline concentrations were determined. In conclusion, serum COL3 concentration might be considered as a potential aid for the diagnosis of endometrosis and fertility prognosis in the mare. In contrast, COL1 and hydroxyproline did not prove to be effective as biomarkers of endometrial fibrosis in this species. Although it is very unlikely that a single blood biomarker could replace a histopathological evaluation, serum COL3 may have clinical applications. Thus, it may be useful to evaluate a group of mares as possible recipients in embryo transfer programs, where performing endometrial biopsies of several mares is not feasible.

Abstract

Collagen pathological deposition in equine endometrium (endometrosis) is responsible for infertility. Kenney and Doig’s endometrial biopsy histopathological classification is the gold standard method for endometrosis evaluation, whereby blood biomarkers identification would be less invasive and could provide additional information regarding endometrosis diagnosis and fertility prognosis. This study aimed to identify blood biomarkers for endometrosis diagnosis (42 mares were used in experiment 1), and fertility assessment (50 mares were used in experiment 2). Reproductive examination, endometrial biopsy histopathological classification (Kenney and Doig) and blood collection were performed. Endometrium and serum collagen type I (COL1) and type III (COL3), and hydroxyproline concentrations were measured (ELISA). Serum COL3 cut-off value of 60.9 ng/mL allowed healthy endometria (category I) differentiation from endometria with degenerative/fibrotic lesions (categories IIA, IIB or III) with 100% specificity and 75.9% sensitivity. This cut-off value enabled category I + IIA differentiation from IIB + III (76% specificity, 81% sensitivity), and category III differentiation from others (65% specificity, 92.3% sensitivity). COL1 and hydroxyproline were not valid as blood biomarkers. Serum COL3 cut-off value of 146 ng/mL differentiated fertile from infertile mares (82.4% specificity, 55.6% sensitivity), and was not correlated with mares’ age. Only COL3 may prove useful as a diagnostic aid in mares with endometrial fibrosis and as a fertility indicator.

Expression of cadherins and some connective tissue components in cow uterus and placenta during pregnancy

The implantation and placental development processes are regulated with cell adhesion molecules and remodeling of the maternal endometrium's extracellular matrices (ECM) and fetal chorion. This study aimed to investigate the distribution and localization of some classical cadherins (E-, N-, and P-cadherins) and extracellular matrix components collagen type 5α1, fibronectin, and laminin in the cow placentomes during pregnancy using immunohistochemical and Western blotting analyses. The study results confirmed the expression of E- and P-cadherins, collagen type Vα1 (COLVα1), fibronectin, and laminin in the cow placentomes, but not N-cadherin. Throughout the pregnancy, E- and P- cadherins, COLVα1, and laminin were localized in the luminal and glandular epithelium of the inter-caruncular endometrium, caruncular epithelium, and the uninucleate (UNCs) and binucleate trophoblast giant cells (BNCs/TGCs). E- cadherin immunoreactivity in the first pregnancy period was strong in the UNCs while moderate in the BNCs/TGCs. However, it was weak in both trophoblast in the second and third pregnancy periods. In the fetal trophoblasts, P- cadherin and laminin immunostainings were more intense in the BNCs/TGCs than UNCs. The fetal and maternal stromal cells were also positive for P- cadherin, COLVα1, fibronectin, and laminin. The immunostaining intensity of COLVα1 and fibronectin in the stromal extracellular matrix of the placentomes decreased as the pregnancy progressed. The endothelia of fetal and maternal vessels were positive for all proteins. The presence and distinct localization of cadherins and ECM proteins in the cow placentome components support the role of these molecules in regulating placental cell growth, migration, and matrix production during pregnancy.

Evolution of the Concepts of Endometrosis, Post Breeding Endometritis, and Susceptibility of Mares

In this paper, the evolution of our understanding about post breeding endometritis (PBE), the susceptibility of mares, and events leading to endometrosis are reviewed. When sperm arrive in the uterus, pro-inflammatory cytokines and chemokines are released. They attract neutrophils and induce modulatory cytokines which control inflammation. In susceptible mares, this physiological defense can be prolonged since the pattern of cytokine release differs from that of resistant mares being delayed and weaker for anti-inflammatory cytokines. Delayed uterine clearance due to conformational defects, deficient myometrial contractions, and failure of the cervix to relax is detected by intrauterine fluid accumulation and is an important reason for susceptibility to endometritis. Multiparous aged mares are more likely to be susceptible. Untreated prolonged PBE can lead to bacterial or fungal endometritis called persistent or chronic endometritis. Exuberant or prolonged neutrophilia and cytokine release can have deleterious and permanent effects in inducing endometrosis. Interactions of neutrophils, cytokines, and prostaglandins in the formation of collagen and extracellular matrix in the pathogenesis of fibrosis are discussed. Endometritis and endometrosis are interconnected, influencing each other. It is suggested that they represent epigenetic changes induced by age and hostile uterine environment.