Peroxisome proliferator-activated receptor expression in the canine endometrium with cystic endometrial hyperplasia-pyometra complex.

The most common uterine diseases in bitches occurring during diestrus are cystic endometrial hyperplasia (CEH) and pyometra. These diseases can coexist as CEH-pyometra complex (CEH-P). Their pathogenesis has not been fully explained. Peroxisome proliferator-activated receptors (PPARs) are important factors regulating mammalian reproductive function and inflammatory processes. Although there is a lack of data concerning the expression of PPARs in the canine endometrium during CEH and CEH-P, we hypothesized that they might be involved in the development of pathological disorders of the canine endometrium. Therefore, the current study was conducted to evaluate and compare PPARα, PPARδ and PPARγ mRNA expression using quantitative real-time PCR (qPCR) and their immunolocalization using immunohistochemistry (IHC) staining in the endometrium of clinically healthy bitches (control group; n = 8) and those with CEH (n = 8) or CEH-P (n = 8). For quantification, the arithmetic means of all intensities of immunostaining from the cells were measured with the optical density. PPARα, PPARδ and PPARγ were detected in the luminal epithelium, glandular epithelium and stromal cells. The mRNA transcription of PPARα was higher in the CEH group than in the control group (p < .05). Additionally, the mRNA expression and immunostaining intensities of PPARδ and PPARγ in the endometrium in the CEH-P group were downregulated relative to those in the control group (p < .05). Moreover, the serum progesterone concentration measured by direct radioimmunoassay was decreased in the CEH-P group compared to the control group (p < .001) and CEH group (p < .05). The obtained results indicate that PPARs are present in the canine endometrium and that their mRNA profile and intensity levels change under pathological conditions such as CEH and CEH-P. This finding may suggest a correlation between changes in the PPAR expression profile and hormonal disturbances, as well as the potential involvement of PPARs in signal transduction during inflammatory processes occurring in the endometrium during CEH-P. These results pave the way to further research into the role of PPARs in the pathogenesis of CEH and CEH-P in female dogs.

Effects of cortisol on prostaglandin F2α secretion and expression of genes involved in the arachidonic acid metabolic pathway in equine endometrium - In vitro study.

Glucocorticoids (GCs) are known to play an important role in maintaining basal and stress-related homeostasis by interacting with endocrine mediators and prostaglandins (PGs). Although a growing body of evidence shows that GCs exert their regulatory action at a multitude of sites in the reproductive axis through corticosteroid receptors, little is known about the direct role of cortisol, an active form of GCs, in the equine endometrium. Thus, the study aimed to determine the effect of cortisol on PGF2α synthesis in the endometrial tissue and cells in vitro. In Exp.1, the immunolocalization and the expression of the glucocorticoid receptor (GCR) in the endometrium throughout the estrous cycle were established. In Exp. 2 and 3, the effects of cortisol on PGF2α secretion and transcripts associated with the arachidonic acid (AA) cascade in endometrial tissues, and cells were defined. Endometrial tissues obtained from the early, mid, and late luteal phases and the follicular phase of the estrous cycle were exposed to cortisol (100, 200, and 400 nM) for 24 h. Endometrial epithelial and stromal cells (early phase of estrous cycle) were exposed to cortisol (100 nM) for 24 h. Then, PGF2α secretion and transcripts associated with the AA cascade (PLA2G2A, PLA2G4A, PTGS2, and PGFS) were assessed. GCR was expressed in the cytoplasm and the nucleus in the luminal and glandular epithelium as well as in the stroma. Endometrial GCR protein abundance was up-regulated at the late luteal phase compared to the mid-luteal phase of the estrous cycle. Cortisol dose-dependently decreased PGF2α secretion, PLA2G2A and PLA2G4A transcripts in endometrial tissues. Additionally, cortisol treatment decreased PGF2α secretion from endometrial epithelial and stromal cells. Moreover, it affected PLA2G2A, PLA2G4A, and PTGS2 transcripts in endometrial stromal cells. These findings suggest that cortisol suppresses the synthesis of PGF2α by affecting the AA cascade in the equine endometrium during the estrous cycle.

The Effects of Prostaglandin E2 Treatment on the Secretory Function of Mare Corpus Luteum Depends on the Site of Application: An in vivo Study.

We examined the effect of prostaglandin (PG) E2 on the secretory function of equine corpus luteum (CL), according to the application site: intra-CL injection vs. an intrauterine (intra-U) administration. Moreover, the effect of intra-CL injection vs. intra-U administration of both luteotropic factors: PGE2 and human chorionic gonadotropin (hCG) as a positive control, on CL function was additionally compared. Mares were assigned to the groups (n = 6 per group): (1) an intra-CL saline injection (control); (2) an intra-CL injection of PGE2 (5 mg/ml); (3) an intra-CL injection of hCG (1,500 IU/ml); (4) an intra-U saline administration (control); (5) an intra-U administration of PGE2 (5 mg/5 ml); (6) an intra-U administration of hCG (1,500 IU/5 ml). Progesterone (P4) and PGE2 concentrations were measured in blood plasma samples collected at -2, -1, and 0 (pre-treatment), and at 1, 2, 3, 4, 6, 8, 10, 12, and 24 h after treatments. Moreover, effects of different doses of PGE2 application on the concentration of total PGF2α (PGF2α and its main metabolite 13,14-dihydro-15-keto-prostaglandin F2α- PGFM) was determined. The time point of PGE2, hCG, or saline administration was defined as hour "0" of the experiment. An intra-CL injection of PGE2 increased P4 and PGE2 concentrations between 3 and 4 h or at 3 and 12 h, respectively (p < 0.05). While intra-U administration of PGE2 elevated P4 concentrations between 8 and 24 h, PGE2 was upregulated at 1 h and between 3 and 4 h (p < 0.05). An intra-CL injection of hCG increased P4 concentrations at 1, 6, and 12 h (p < 0.05), while its intra-U administration enhanced P4 and PGE2 concentrations between 1 and 12 h or at 3 h and between 6 and 10 h, respectively (p < 0.05). An application of PGE2, dependently on the dose, supports equine CL function, regardless of the application site, consequently leading to differences in both P4 and PGE2 concentrations in blood plasma.

Neutrophils, monocytes and other immune components in the equine endometrium: Friends or foes?

The innate and adaptive immune mechanisms are key components of regulation of reproductive physiological function and uterine disorders in equine uterus. The predominant immunological response in equine endometrium, characterized by an innate immune response, occurs under estrogens influence, in the follicular phase. Although, the increase in immune-related genes in equine endometrium during estrus has been suggested to play a role in uterine clearance after mating, immune cells and their product, i.e. cytokines play also mandatory role in the luteal development and maintenance, regression of equine corpus luteum, as well as in early pregnancy. Innate immune response is nonspecific and acts as the first line of defense against pathogens, foreign stimuli that include constituents of seminal fluid and local infections (endometritis). It has been recently established that a phagocytosis-independent mechanism to restrain bacteria, by means of neutrophil extracellular traps (NETs) formation, is involved in pathogenesis of in mare endometrial fibrosis (endometrosis). Moreover, persistent macrophages and mast cell activation could also have pro-fibrotic roles by secreting great amounts of pro-fibrotic factors and lead to fibrosis. This review will highlight the involvement of immune key components of the innate and adaptive immune system and their products in equine uterus and their contribution to reproductive physiological function and uterine disorders.

Evidence for Increased Content of PGF2α, PGE2, and 6-keto-PGF1α in Endometrial Tissue Cultures From Heavy Draft Mares in Anestrus With Endometritis.

Endometritis is one of the most important causes of infertility in mares. Mares may suffer from endometritis outside the breeding season; however, pathological condition is often undiagnosed in anestrus. The aim of this study was to examine whether the secretion profiles of prostaglandin F2α (PGF2α), prostaglandin E2 (PGE2), and a metabolite of prostacyclin I2 (6-keto-PGF1α) differ in endometrial tissue cultures of heavy draft mares in anestrus with endometritis compared to those without endometritis. The endometrial biopsies were collected from 51 heavy draft mares. Inclusion criteria for the control group were absence of endometritis confirmed by histology and no ovarian activity. Inclusion criteria for the experimental group were presence of endometritis showing polymorphonuclear cells and/or lymphocytes infiltration in endometrium and no ovarian activity. Retrospectively, 22 mares were enrolled in this study. The content of PGF2α (P < .05) and PGE2 (P < .001) in the culture medium was distinctly elevated in mares suffering from endometritis, compared to control mares. The relative mRNA abundance responsible for prostaglandins synthesis, that is, PGF2α synthase (PGFS; P < .01), PGE2 synthase (PGES; P < .01), and prostaglandin-endoperoxide synthase (PTGS2; P < .01), were also increased in endometrial tissue of mares with endometritis compared to control mares. The content of 6-keto-PGF1α (P < .0001) in endometrial tissue cultures from mares with endometritis was strikingly elevated compared to those without endometritis; however, plasma concentration of 6-keto-PGF1α was not significantly different between experimental and control groups. This leads to the conclusion that augmented endometrial secretion of PGF2α, PGE2, and 6-keto-PGF1α is associated with endometritis even in mares in anestrus.

Effect of TGFß1, TGFß3 and keratinocyte conditioned media on functional characteristics of dermal fibroblasts derived from reparative (Balb/c) and regenerative (Foxn1 deficient; nude) mouse models.

Skin injuries in mammals are healed through repair or regeneration. Our previous studies demonstrated that deficient expression of the transcription factor Foxn1 in epidermis of nude mice accounts for their skin's pronounced regenerative properties. Since homeostasis within the skin depends on complex interactions between the epidermal and underlying dermal layers, the present study characterizes and compares isolated dermal fibroblasts (DFs) between regenerative nude (Foxn1 deficient) mice and their wild-type Balb/c counterparts. Nude DFs exhibited a higher cumulative number of population doublings (cumulative PD) at low seeding density and increased adipogenic differentiation capacity relative to their Balb/c DF counterparts. Nude DFs displayed reduced migration and gel contraction, functional features associated with wound healing. The comparison of transforming growth factor ß family (TGFß) expression showed significantly higher levels of Tgfß3 transcript between nude and Balb/c mice but no differences were detected for Tgfß1. Nude DFs were specifically sensitive to the presence of the pro-regenerative TGFß3 isoform, showing increased collagen I deposition and alpha smooth muscle actin expression. Viability of Balb/c DFs was stimulated by keratinocyte conditioned media (KCM) from Balb/c (Foxn1 active) but inhibited by nude (Foxn1 deficient) KCM. In contrast, nude DFs did not respond to either KCMs with respect to their metabolic activity. Collectively, the enhanced plasticity and greater sensitivity of nude DFs to TGFß3 stimulation are indicative of and consistent with their pro-regenerative characteristics. These data support the hypothesis that epidermal Foxn1 plays a critical role in determining the DFs regenerative phenotype.