Sex steroids drive the remodeling of oviductal extracellular matrix in cattle

From the laboratory to the field: how to mitigate pregnancy losses in embryo transfer programs?

Pregnancy losses negatively affect the cattle industry, impacting economic indices and consequently the entire production chain. Early embryonic failure has been an important challenge in the embryo industry because proper identification of embryo death at the beginning of gestation is difficult. This review aimed to provide a better understanding on reproductive failure and the relationship between early embryonic loss and different reproductive biotechniques. This review also considers insights and possible strategies for reducing early embryonic loss. The strategies addressed are as follows: i) great impact of rigorous embryo evaluation on reducing embryo losses; ii) selection of recipients at the time of transfer, taking into account health and nutritional status, and classification of the corpus luteum using ultrasound, either in area or vascularization; and iii) paternal effect as one of the factors that contribute to pregnancy losses, with a focus on embryo transfer.

Denatured collagen in keratin layers and smooth muscles of teats with low or high teat apex scores in Holstein dairy cows

We hypothesized that teats with a teat apex score (TAS) of 4 on a 4-point scale would exhibit elevated levels of denatured collagen compared with teats with lower TAS. We procured keratin layer and smooth muscle samples from Holsteins with TAS ranging from 1 to 4, as well as from crossbred heifers (Japanese Black male and Holstein female) with TAS of 1. Teats with a TAS of 4 demonstrated increased total collagen content, higher amounts of type I collagen (the harder, thicker variant), and reduced amounts of type III collagen (the softer, thinner variant) compared with teats with lower TAS. Teats with TAS of 3 and 4 exhibited evidence of damaged collagen in smooth muscle layers compared with teats with TAS of 1. Additionally, we identified 47-kDa heat shock protein-positive fibroblasts in the smooth muscles of teats with TAS of 3 and 4. Therefore, the smooth muscle of teats with a TAS of 4 exhibited increased amounts of denatured collagen in comparison to teats with lower TAS.

In vivo dynamics of pro-inflammatory factors, mucins, and polymorph nuclear neutrophils in the bovine oviduct during the follicular and luteal phase

Dynamic functional changes in the oviductal microenvironment are the prerequisite for the establishment of pregnancy. The objective of this study was to gain the first insights into oestrous cycle-dependent dynamics of polymorph nuclear neutrophils (PMN) and the mRNA abundance of selected genes and their correlations in the oviduct of living cows. Mini-cytobrush samples were taken from the oviducts of healthy heifers (n = 6) and cows (n = 7) during the follicular (FOL) and luteal phase (LUT) by transvaginal endoscopy. Total RNA was isolated from the samples and subjected to reverse transcription-quantitative PCR for selected pro-inflammatory factors, glycoproteins, and a metabolic marker. The percentage of PMN was determined by cytological examination. The mean PMN percentage was 2.8-fold greater during LUT than FOL. During LUT, significantly greater mRNA abundance of the pro-inflammatory factors IL1B, CXCL1, CXCL3, and CXCL8 was observed. The OVGP1 mRNA abundance was twice as high during FOL than in LUT. Pearson correlation, principal component analysis and heatmap analyses indicated characteristic functional patterns with strong correlations among investigated factors. Using this novel approach, we illustrate complex physiological dynamics and interactions of the mRNA expression of pro-inflammatory factors, mucins, OVGP1, and PMN in the oviduct during the oestrous cycle.

Specific locations and amounts of denatured collagen and collagen-specific chaperone HSP47 in the oviducts and uteri of old cows as compared with those of heifers

Collagen, the most abundant extra-cellular matrix in oviducts and uteri, performs critical roles in pregnancies. We hypothesised that the locations and amounts of both denatured collagen and the collagen-specific molecular chaperone 47-kDa heat shock protein (HSP47) in the oviducts and uteri of old cows are different compared with those of young heifers because of repeated pregnancies. Since detecting damaged collagen in tissues is challenging, we developed a new method that uses a denatured collagen detection reagent. Then, we compared damaged collagen in the oviducts and uteri between post-pubertal growing nulliparous heifers (22.1±1.0months old) and old multiparous cows (143.1±15.6months old). Further, we evaluated the relationship between denatured collagen and HSP47 by combining this method with fluorescence immunohistochemistry. Picro-sirius red staining showed collagen in almost all parts of the oviducts and uteri. Expectedly, damaged collagen was increased in the oviducts and uteri of old cows. However, damaged collagen and HSP47 were not located in the same area in old cows. The number of fibroblasts increased, suggesting the presence of fibrosis in the oviducts and uteri of old cows. These organs of old cows showed higher HSP47 protein amounts than those of heifers. However, the uteri, but not oviducts, of old cows had lower HSP47 mRNA amounts than those of heifers. These findings revealed the specific location and amounts of denatured collagen and HSP47 in the oviducts and uteri of old cows compared with those of heifers.

The role of the oviduct and extracellular vesicles during early embryo development in bovine

The oviduct is an important reproductive structure that connects the ovary to the uterus and takes place to important events such as oocyte final maturation, fertilization and early embryonic development. Thus, gametes and embryo can be directly influenced by the oviductal microenvironment composed by epithelial cells such secretory and ciliated cells and oviductal fluid. The oviduct composition is anatomically dynamic and is under ovarian hormones control. The oviductal fluid provides protection, nourishment and transport to gametes and embryo and allows interaction to oviductal epithelial cells. All these functions together allows the oviduct to provides the ideal environment to the early reproductive events. Extracellular vesicles (EVs) are biological nanoparticles that mediates cell communication and are present at oviductal fluid and plays an important role in gametes/embryo - oviductal cells communication. This review will present the ability of the oviducts based on its dynamic and systemic changes during reproductive events, as well as the contribution of EVs in this process.

Aloe vera increases collagen fibres in extracellular matrix and mRNA expression of peroxiredoxin-6 in bovine ovarian cortical tissues cultured in vitro

In vitro culture of ovarian tissue containing primordial follicles is an important tool to study the initiation of follicular populations and to develop efficient culture systems to support in vitro follicle growth. Considering that in vitro culture favours oxidative stress, it is very important to supplement culture medium with antioxidant substances such as Aloe vera extract. This study aims to evaluate the effects of different concentrations of Aloe vera on the distribution of collagen fibres in the extracellular matrix, follicular activation, development and survival in bovine ovarian cortical tissues cultured in vitro, as well as on expression of mRNAs for antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxiredoxin 6 (PRDX6) and glutathione peroxidase 1 (GPX1)]. To this end, ovarian cortical tissues were cultured for 6 days in α-MEM alone or supplemented with different concentrations of Aloe vera extract (1.0, 5.0, 10.0 or 50.0%). After culture, fragments were fixed and processed histologically to evaluate follicular morphology and activation, as well as the extracellular matrix by staining with picrosirius red. The levels of mRNA for SOD, CAT, PRDX6 and GPX1 in cultured ovarian tissues were evaluated by real-time polymerase chain reaction (PCR). Ovarian tissues cultured with 10.0 or 50.0% Aloe vera had higher percentages of collagen fibres than tissues cultured in control medium. A significant increase in developing follicles was observed in ovarian tissues cultured in α-MEM alone or supplemented with 10% Aloe vera when compared with fresh control or tissues cultured with 1.0% Aloe vera. Presence of Aloe vera did not influence the percentage of morphologically normal follicles when compared with control medium. Ovarian tissues cultured with 50.0% Aloe vera had higher percentages of morphologically normal follicles than those cultured with 10.0% Aloe vera. Furthermore, 10% Aloe vera significantly increased mRNA levels for PRDX6. In conclusion, 10.0% Aloe vera improves extracellular matrix distribution in cultured tissues and increases the expression of mRNA for PRDX6 after 6 days in vitro.

Steroidal Regulation of Oviductal microRNAs Is Associated with microRNA-Processing in Beef Cows

Information on molecular mechanisms through which sex-steroids regulate oviductal function to support early embryo development is lacking. Here, we hypothesized that the periovulatory endocrine milieu affects the miRNA processing machinery and miRNA expression in bovine oviductal tissues. Growth of the preovulatory follicle was controlled to obtain cows that ovulated a small follicle (SF) and subsequently bore a small corpus luteum (CL; SF-SCL) or a large follicle (LF) and large CL (LF-LCL). These groups differed in the periovulatory plasmatic sex-steroid's concentrations. Ampulla and isthmus samples were collected on day four of the estrous cycle. Abundance of DROSHA, DICER1, and AGO4 transcripts was greater in the ampulla than the isthmus. In the ampulla, transcription of these genes was greater for the SF-SCL group, while the opposite was observed in the isthmus. The expression of the 88 most abundant miRNAs and 14 miRNAs in the ampulla and 34 miRNAs in isthmus were differentially expressed between LF-LCL and SF-SCL groups. Integration of transcriptomic and miRNA data and molecular pathways enrichment showed that important pathways were inhibited in the SF-SCL group due to miRNA control. In conclusion, the endocrine milieu affects the miRNA expression in the bovine oviduct in a region-specific manner.

S100A8, which increases with age, induces cellular senescence-like changes in bovine oviduct epithelial cells

PROBLEM

The oviduct is an essential component in reproduction and oviduct epithelial cells (OECs) secrete various types of cytokine. However, mechanisms of aging and inflammation of OECs are unknown. We previously reported the age-dependent functional changes of bovine OECs such that aged OECs expressed higher levels of inflammatory cytokines. We selected S100A8 and S100A9 as molecules expressed more highly in aged OECs, as candidates to induce age-related changes, and investigated using bovine OECs.

METHOD OF STUDY

The OECs were isolated from bovine oviductal tissues (Aged, more than 120 months; Young, between 30 and 50 months) and cultured.

RESULTS

Aged OECs exhibited higher senescence-associated (SA)-β-gal staining (a biomarker of cellular senescence) and mRNA expression of SA-inflammatory cytokines than young OECs. Cellular senescence occurred in both young and aged OECs upon passaging the cells. Treatment with S100A8, but not S100A9, resulted in the induction of cellular senescence in bovine OECs. Both S100A8 and S100A9 stimulated the secretion of the inflammatory cytokine IL-8 from bovine OECs. S100A8-induced IL-8 secretion was dependent on receptor RAGE, AP-1 activation, and reactive oxygen species production. In addition, S100A8 reduced the content of collagen while inducing the expression of matrix metalloproteinases, suggesting the induction of dysregulation of the extracellular matrix in OECs.

CONCLUSION

We suggest that bovine OECs recognize an excessive increase in age-associated DAMPs, such as S100A8 and S100A9, and that these signals may contribute to chronic oviductal inflammation, resulting in infertility associated with oviductal dysfunction.