Proteins and enzymes in uterine lavage fluid of postpartum and nonparturient mares

Inflammatory Markers in Uterine Lavage Fluids of Pregnant, Non-Pregnant, and Intrauterine Device Implanted Mares on Days 10 and 15 Post Ovulation

Simple Summary

While intrauterine devices (IUDs) are used to prevent disturbing oestrous behaviour in sport mares, their mechanism of action has not been elucidated. The presence of an embryo or an IUD prevents cyclooxygenase-2 (COX-2) and subsequently prostaglandin (PG) release and luteolysis. It has been suggested that a plastic sphere would mimic the embryo by mechanotransduction. However, there is some evidence that IUDs also cause endometrial inflammation, which might contribute to luteostasis. The aim of this study was to investigate the presence and time course of possible inflammation by evaluating changes in uterine fluid composition. On Day 10 after ovulation, events leading to COX-2 and prostaglandin F_2α (PGF_2α) inhibition start, whereas either luteolysis occurs or the corpus luteum is maintained on Day 15. Therefore, uterine lavage fluid was evaluated at two time points in inseminated mares, either pregnant or not, and in mares inserted with an IUD. On Day 10, PGF_2α concentration in the fluid was significantly lower in the IUD group than in the pregnant mare one but did not differ from the non-pregnant mare group. On Day 15, the IUD group had significantly higher levels of the modulatory cytokine IL-10 and inhibin A, which could indicate previous inflammation and resolution stage.

Abstract

Intrauterine devices (IUDs) are used in mares to suppress oestrous behaviour, but the underlying mechanism is yet to be elucidated. The presence of an embryo or an IUD prevents cyclooxygenase-2 (COX-2) and, subsequently, prostaglandin (PG) release and luteolysis. However, inflammation may also be involved. Endometrial inflammatory markers in uterine lavage fluid were measured on Day 10 (EXP 1, n = 25) and Day 15 (EXP 2, n = 27) after ovulation in inseminated mares, non-pregnant or pregnant, and in mares in which a small plastic sphere had been inserted into the uterus 4 (EXP 1) or 3 days (EXP 2) after ovulation. Uterine lavage fluid samples were analysed for nitric oxide (NO), prostaglandin E₂ (PGE₂) (only EXP 1), prostaglandin F_2α (PGF_2α), inhibin A and cytokines, and blood samples for progesterone and oestradiol. On Day 10, the concentration of PGF_2α was lower (p < 0.05) in the IUD group than in pregnant mares. The concentration of the modulatory cytokine IL-10 was significantly higher in the IUD group in comparison to non-pregnant mares, and inhibin A was significantly higher in IUD mares than in the pregnant counterparts on Day 15. The results suggest that the presence of IUD causes endometrial inflammation which is at a resolution stage on Day 15.

Effects of intrauterine devices on proteins in the uterine lavage fluid of mares

Intrauterine devices block luteolysis in cyclic mares, but the underlying mechanism is unknown. To clarify the mechanisms, the protein profile of the endometrial secretome was analyzed using two-dimensional difference gel electrophoresis (2D-DIGE). Twenty-seven mares were classified according to whether they were inseminated (AI) or had an intrauterine device (IUD), a water-filled plastic sphere, inserted into the uterus on Day 3 after ovulation. Uterine lavage fluids were collected on Day 15 from pregnant inseminated mares (AI-P; n = 8), non-pregnant inseminated mares (AI-N; n = 4), and mares with IUD (n = 15). The IUD group was further divided into prolonged (IUD-P; n = 7) and normal luteal phase (IUD-N; n = 8) groups on the basis of ultrasound examinations, serum levels of progesterone and PGFM on Days 14 and 15, and COX-2 results on Day 15. Four mares from each group were selected for the 2D-DIGE analyses. Ten proteins had significantly different abundance among the groups, nine of the proteins were identified. Malate dehydrogenase 1, increased sodium tolerance 1, aldehyde dehydrogenase 1A1, prostaglandin reductase 1, albumin and hemoglobin were highest in pregnant mares; T-complex protein 1 was highest in non-pregnant mares; and annexin A1 and 6-phosphogluconolactonase were highest in IUD mares. The results suggest that the mechanism behind the intrauterine devices is likely related to inflammation.

Endometrial Status in Queens Evaluated by Histopathology Findings and Two Cytological Techniques: Low-Volume Uterine Lavage and Uterine Swabbing

Simple Summary

The endometrium health of feline queens can be difficult to assess due to the reduced size of the uterus, which hinders representative biopsy sampling. This may result in limitations in diagnosing endometritis, and consequently in detecting infertility problems. Although histology is considered the most reliable technique for diagnosing endometritis in many species, cytology is also gaining importance and may be an alternative tool for evaluating the endometrium in small species. Two different common cytological techniques (uterine lavage and uterine swabbing) were compared to determine the reliability of cytology for evaluating the endometrium status in queens. Histopathological and bacteriological information was used for the control methods. Our results demonstrated that cytology may be a useful diagnostic tool for assessing the endometrial status. In addition, when comparing cytological techniques, the uterine lavage method was more representative than uterine swabbing.

Abstract

Endometritis is associated with fertility problems in many species, with endometrial biopsy being the main diagnostic tool. In feline queens, the reduced size of the uterus may make it difficult to obtain representative diagnostic samples. Endometrial cytology may represent a valuable diagnostic tool for evaluating the health status of the endometrium in queens. Fifty domestic shorthair queens were included and divided into two cytological diagnostic technique groups, the uterine lavage (UL; n = 28) and uterine swabbing (US; n = 22) groups. Cytological results were compared with histopathological and bacteriological information. Changes in the histopathological patterns were also evaluated and compared with progesterone levels to confirm previous published data. Furthermore, the results from both cytological sampling methods were compared to evaluate the utility of each method. Endometritis was ruled out in all queens by means of histology and microbiology. Leukocyte counts and red blood cell/endometrial cell ratios were significantly higher in US than UL samples. Additionally, UL sampling is less affected by blood contamination and cells are better preserved. The combination of endometrial cytology and uterine culture might be useful for evaluating the endometrial characteristics in queens. The UL evaluation method is more representative of the actual endometrial status than the US technique.

Cyclooxygenase-2 is inhibited in prolonged luteal maintenance induced by intrauterine devices in mares

Treatment with intrauterine devices (IUD) prolongs luteal phases in mares, but the mechanism for this has not been fully elucidated. The aims of the present study were to examine how IUDs affect the uterus to induce longer luteal phases, particularly the role of cyclooxygenase-2 (COX-2) in the maintenance of the corpus luteum (CL). Twenty-seven reproductively normal mares were included: 12 were inseminated (AI), and 15 were fitted with IUDs. Blood samples for progesterone were obtained on Days 0, 3, 5, 7, 9, 11, 13, 14, and 15 (relative to day of ovulation). The groups were further divided into non-pregnant (AI-N, n = 4), pregnant (AI-P, n = 8), normal (IUD-N, n = 8) and prolonged luteal phase (IUD-P, n = 7) based on ultrasonic examinations and serum progesterone concentrations on Days 14 and 15. Blood sampling to quantify the PGF_2α metabolite (PGFM) was performed through a catheter hourly from 15:00 to 20:00 h on Day 14, and from 6:00 until 13:00 h on Day 15. On Day 15, a low-volume uterine lavage followed by an endometrial biopsy was performed. Estradiol concentration in the Day 15 serum and lavage fluid was determined, while the abundance of COX-2 was evaluated in the biopsy specimens using western blotting (WB) and immunohistochemistry (IHC). All pregnant mares were negative for COX-2 in IHC samples and 5 of 8 were negative in WB samples while all mares of the IUD-N group were positive for COX-2. Of the seven mares in the IUD-P group, five and four were negative for COX-2 with the IHC and WB samples, respectively. The results from this study indicate that IUDs, when effective, suppress COX-2, leading to the inhibition of PGF2α release and maintenance of CL.

Effects on the equine endometrium of cervical occlusion after insemination

Cervical patency is considered to be important for uterine drainage after mating or artificial insemination (AI), and failure to relax or premature tightening of the cervix can lead to persistent endometritis. This study investigated the hypothesis that cervical occlusion after AI increases accumulation of fluid, polymorphonuclear leukocytes (PMNs), and cytokines in the uterine lumen. Endometrial swabs were obtained from 29 normal cyclic mares during the first, third, and fifth estrus and biopsies during the first and fifth estrus. All mares were inseminated during the second and fourth estrus. In either the second or fourth estrus, a clamped catheter was inserted into the uterus immediately after AI. Accumulation of intrauterine fluid was evaluated by transrectal ultrasonography at 0, 6, 25, and 48 hours. Fluid was drained from the catheter at either 25 hours (TxA) or 6 and 25 hours after AI (TxB). In the control estrus (TxC, no catheters), fluid was obtained by a tampon at 25 hours after AI. The uteri were then lavaged with Ringer's solution, after which the catheters were withdrawn. Sequences of treatments in the second and fourth estrus were A followed by C, C followed by A, B followed by C, and C followed by B in groups AC, CA, BC, and CB, respectively. Five mares lost their catheters and were excluded from the study. Scores for total inflammation, gland dilation, and lymphatic lacunae in the uterine biopsies did not differ significantly between groups or estrous periods. In contrast, periglandular fibrosis scores increased in all groups during the experiment. At 25 hours after AI in the second estrus, the mares with the catheters had larger accumulations of fluid (P < 0.05) and higher concentrations and total numbers of PMNs in uterine fluid (P < 0.05) than the mares without catheters. In the fourth estrus, the total number of PMNs was lower in TxB than in TxA at 25 hours (P < 0.05). Concentrations of PMNs in TxC were 10 times higher in the fourth estrus than the second. Within mare groups AC and BC, total numbers of PMNs in treatment C (fourth estrus) were as high as in TxA and B (second estrus). Expression of IL-1β, IL-6, IL-10 and TNF-α, analyzed by Western blotting, did not differ significantly between the treatments or estrous periods. It is concluded that a closed cervix after insemination results in pronounced inflammation of the mare's endometrium. Furthermore, this kind of severe insult may lead to permanent pathologic changes in the endometrium, including fibrosis.

Uterine involution and endometrial function in postpartum pony mares

OBJECTIVE

To determine endometrial regeneration in postpartum mares by analysis of histologic features, apoptosis and cell proliferation markers, lectin binding, cytokines, and progesterone and estrogen receptors in endometrial biopsy specimens.

ANIMALS

9 postpartum mares.

PROCEDURES

Mares were examined on postpartum days 1, 9, and 16, and uterine biopsy specimens were obtained for histologic examination. Lectin binding was analyzed histochemically, and expressions of Ki-67 antigen (proliferation marker), lysozyme, and caspase 3 (apoptosis marker) were studied immunohistochemically. Gene expressions for cytokines (interleukin-1beta, -6 and -8 and tumor necrosis factor-alpha), cyclooxygenase 2, prostaglandin-E-synthase, and estrogen and progesterone receptors were determined by use of quantitative real-time PCR assay.

RESULTS

On day 1, neutrophils predominated but by day 9 had largely been replaced by lymphocytes and macrophages. High numbers of cells with staining for caspase 3 were found on day 1, but numbers decreased by day 9. In contrast, the number of cells with staining for Kiel 67 antigen increased between days 1 and 9. Lectin binding to the endometrium changed over time. Relative mRNA expressions for cytokines and prostaglandin-E-synthase did not differ among days. Expressions of progesterone and estrogen receptors were minimal on day 1 and increased by day 9.

CONCLUSIONS AND CLINICAL RELEVANCE

Early postpartum endometrial cells underwent apoptosis, but during the second week, postpartum proliferation of cells predominated. Lectin binding reflected changes in endometrial glycocalyx patterns. Increased expression of estrogen receptors allowed the endometrium to respond to estrogen during foal heat, and in subsequent diestrus, the endometrium was able to respond to progesterone.