Oestrous cycle-related changes in production of Toll-like receptors and prostaglandins in the canine endometrium

Prostaglandin and antigestagen in pyometra bitches: vascular and stereological effect

Effects of conservative treatment on uterine blood flow and morphometric findings are still unknown in bitches. Thus, this study aimed to compare uterine changes of pyometra bitches subjected to distinct modes of treatment. Pyometra bitches were assigned to: OHE (ovariohysterectomy immediately after diagnosis), Aglepristone (days 1, 2 and 8) and Associative (aglepristone treatment coupled with cloprostenol for 7 days) groups. After 9 days, bitches were ovariohysterectomized. Before surgery, uterine area was measured ultrasonographically and the uterine artery Doppler velocimetry analyzed blood flow velocity and indexes. Uterine horns were classified according to resistance index (RI) as more compromised and less compromised. Endometrial vasculature was quantitatively evaluated by color flow Doppler. Blood samples were collected to determine nitric oxide (NO) concentrations. Histological uterine structures were quantified by stereology and VEGF-A (vascular endothelial growth factor) and eNOS were (endothelial nitric oxide synthase) immunohistochemically analyzed. Aglepristone and Associative groups had lower uterine area and vascularization, and higher blood flow velocity and indexes compared to OHE group. Less compromised horn of Associative group had higher blood flow velocity compared to OHE group. Aglepristone group presented lower inflammatory infiltrate and larger uterine stroma. Associative group had lower volume density and absolute surface of endometrial cysts and lower VEGF-A expression for glandular epithelium and stromal cells. Blood NO and e-NOS immunostaining were not different among groups. In conclusion, association between aglepristone and prostaglandin is more effective in decreasing uterine vascularization and modulating uterine blood flow. Moreover, associative therapy promotes marked morphological changes.

Cell-Specific Expression Pattern of Toll-Like Receptors and Their Roles in Animal Reproduction

Toll-like receptors (TLRs), a part of the innate immune system, have critical roles in protection against infections and involve in basic pathology and physiology. Secreted molecules from the body or pathogens could be a ligand for induction of the TLR system. There are many immune and non-immune types of cells that express at a least single TLR on their surface or cytoplasm. Those cells may be a player in a defense system or in the physiological regulation mechanisms. Reproductive tract and organs contain different types of cells that have essential functions such as hormone production, providing an environment for embryo/fetus, germ cell production, etc. Although lower parts of reproductive organs are in a relationship with outsider contaminants (bacteria, viruses, etc.), upper parts should be sterile to provide a healthy pregnancy and germ cell production. In those areas, TLRs bear controller or regulator roles. In this chapter, we will provide current information about physiological functions of TLR in the cells of the reproductive organs and tract, and especially about their roles in follicle selection, maturation, follicular atresia, ovulation, corpus luteum (CL) formation and regression, establishment and maintenance of pregnancy, sperm production, maturation, capacitation as well as the relationship between TLR polymorphism and reproduction in domestic animals. We will also discuss pathogen-associated molecular patterns (PAMPs)-induced TLRs that involve in reproductive inflammation/pathology.

Alterations in Toll-Like Receptor 7 and -9 mRNA Levels in Lungs after Ovariohysterectomy in a Pyometra Mouse Model

BACKGROUND

Pyometra (P) leads to sepsis and multiple organ dysfunction syndrome. Toll-like receptors (TLRs) recognize pathogens which can cause P. The aim of this study was to investigate TLR-7 and -9 via the MYD88 pathway and the nuclear factor kappa B (NFκB) response in the uterus of a P mouse model before and after ovariohysterectomy (RP) as well as potential lung injury.

MATERIALS AND METHODS

200 female C57BL/6J mice were randomly divided into groups (N = 10/subgroup; sham 1, 2, 3, 7; P1, 2, 3, 7; 1RP1, 2, 3, 7; 2RP1, 2, 3, 7; 3RP1, 2, 3, 7) according to the day of euthanasia. Pathogens were administrated in the groups P and RP in order to induce P.

RESULTS

Alterations in blood chemistry, histopathology, and RT-qPCT analysis before (P) and after RP were observed. Significant correlations were also found between MYD88, NFκB, and TLR9 in P and RP groups in the lungs and in RP groups in the uterus, suggesting that the immune system responded via the TLR9-MYD88 pathway.

CONCLUSIONS

This is the first report of immunohistochemical TLR-7 and -9 localization and of TLR-7, -9, MYD88, and NFκB mRNA expression in the uterus causing lung injury in a P mouse model.

Disruption of female reproductive function by endotoxins

Endotoxemia can be caused by obesity, environmental chemical exposure, abiotic stressors and bacterial infection. Circumstances that deleteriously impact intestinal barrier integrity can induce endotoxemia, and controlled experiments have identified negative impacts of lipopolysaccharide (LPS; an endotoxin mimetic) on folliculogenesis, puberty onset, estrus behavior, ovulation, meiotic competence, luteal function and ovarian steroidogenesis. In addition, neonatal LPS exposures have transgenerational female reproductive impacts, raising concern about early life contacts to this endogenous reproductive toxicant. Aims of this review are to identify physiological stressors causing endotoxemia, to highlight potential mechanism(s) by which LPS compromises female reproduction and identify knowledge gaps regarding how acute and/or metabolic endotoxemia influence(s) female reproduction.

Toll-like receptor expression patterns in the rat uterus during post partum involution

Toll-like receptors (TLRs) belong to a family of pathogen recognition receptors and play critical roles in detecting and responding to invading pathogens. TLR expression could be significant because, in the uterus, the reproductive tract is an important site of exposure to and infection by pathogens during the post partum involution period. To clarify the expression and localisation patterns of TLRs in the rat uterus on Days 1, 3, 5 and 10 post partum (PP1, PP3, PP5 and PP10 respectively), immunohistochemistry and western blotting were used to analyse TLR1-7, TLR9 and TLR10. The immunohistochemistry results indicated that TLR1-7, TLR9 and TLR10 were localised in both the cytoplasm and nuclei of luminal and glandular epithelium, stromal fibroblasts and myometrial cells in the rat uterus. In the luminal epithelium, TLR4-7 were also found in lateral membranes, whereas TLR10 was present in apical membranes. Western blot analysis revealed that the expression of TLR proteins increased with the number of days post partum, reaching a maximum on PP10, although levels did not differ significantly from those on PP1 (P>0.05). These findings confirm that TLR1-7, TLR9 and TLR10 are constitutively expressed in uterine cells and that localisation pattern of TLRs in the endometrium varies with structural changes in the uterus on different days of involution. These results suggest that TLRs may play a role in uterine repair and remodelling during physiological involution.

Immunomodulation in the canine endometrium by uteropathogenic Escherichia coli

This study was designed to evaluate the role of E. coli α-hemolysin (HlyA) in the pathogenesis of canine pyometra, and on the immune response of canine endometrial epithelial and stromal cells. In Experiment 1, the clinical, hematological, biochemical and uterine histological characteristics of β-hemolytic and non-hemolytic E. coli pyometra bitches were compared. More (p < 0.05) metritis cases were observed in β-hemolytic E. coli pyometra uteri than in non-hemolytic E. coli pyometra uteri. β-hemolytic E. coli pyometra endometria had higher gene transcription of IL-1β and IL-8 and lower gene transcription of IL-6 than non-hemolytic E. coli pyometra endometria (p < 0.01). In Experiment 2, the immune response of endometrial epithelial and stromal cells, to hemolytic (Pyo18) and non-hemolytic E. coli strains (Pyo18 with deleted hlya-Pyo18ΔhlyA- and Pyo14) were compared. Following 4 h of incubation, Pyo18 decreased epithelial cell numbers to 54% (p < 0.001), and induced death of all stromal cells (p < 0.0001), whereas Pyo18ΔhlyA and Pyo14 had no effect on cell numbers. Compared to Pyo18ΔhlyA and Pyo14, respectively, Pyo18 induced a lower transcription level of IL-1β (0.99 vs 152.0 vs 50.9 fold increase, p < 0.001), TNFα (3.2 vs 49.9 vs 12.9 fold increase, p < 0.05) and IL-10 (0.4 vs 3.6 vs 2.6 fold increase, p < 0.001) in stromal cells, after 1 h of incubation. This may be seen as an attempt of hemolytic E. coli to delay the activation of the immune response. In conclusion, endometrial epithelial and stromal cell damage induced by HlyA is a potential relevant step of E. coli virulence in the pathogenesis of pyometra.

Comparison of the effect of lipopolysaccharide on tumor necrosis factor α (TNF-α) secretion and TNF and TNFR1 mRNA levels in feline endometrium throughout the estrous cycle during pyometra and after medroxyprogesterone acetate treatment

Endotoxins released by Gram-negative bacteria are potent stimulators of tumor necrosis factor α (TNF-α) production. The objectives of this study were to evaluate plasma levels of TNF-α, TNF-α secretion, and mRNA levels of TNF and TNF-α receptor type 1 (TNFR1) following exposure to lipopolysaccharide (LPS). For this, we used cultured endometrial cells or organ cultures, throughout the estrous cycle, after hormone treatment with medroxyprogesterone acetate (MPA), and during pyometra. Plasma TNF-α concentrations were increased in animals at estrus (P < 0.05) compared to other groups. In the LPS-challenged endometrium, secretion of TNF-α by tissues collected during estrus increased (P < 0.001) compared to that of other groups. LPS, alone or combined with TNF-α, upregulated TNF gene expression in the feline endometrium at diestrus (P < 0.001 for both treatments), in queens treated short-term with MPA (P < 0.01 and P < 0.05, respectively) and in queens treated long-term with MPA (P < 0.01 and P < 0.001, respectively). During pyometra, TNF and TNFR1 mRNA were increased only after tissues were challenged with TNF-α and LPS (P < 0.001 and P < 0.01, respectively). When cultured endometrial cells were challenged with LPS, the concentration of TNF-α increased only in epithelial cells after 4 h and 12 h (P < 0.05 and P < 0.01, respectively). Since LPS did not affect stromal cells, but TNF-α increased its own transcript after 2 h (P < 0.01), 4 h (P < 0.05) and 12 h (P < 0.001), we assume that stromal cells are not directly involved in pathogen recognition, as was the case for epithelial cells.

Prostaglandin release by cultured endometrial tissues after challenge with lipopolysaccharide and tumor necrosis factor α, in relation to the estrous cycle, treatment with medroxyprogesterone acetate, and pyometra

To better understand the pathogenesis of endometrial changes in cats associated with administration of progestagen contraceptives and with pyometra, we examined local variability of the prostaglandin synthesis system after challenge with either tumor necrosis factor α (TNF-α) or lipopolysaccharide (LPS) in organ cultures of endometrial tissues derived from cyclic cats, cats treated with medroxyprogesterone acetate (MPA), or cats with pyometra, as well as in cultured endometrial epithelial and stromal cells. In addition, spontaneous prostaglandin secretion was compared in endometria from different experimental groups. Data gathered in the present study show that the concentration of PGE2 in supernatants was increased only in endometrial organ cultures from cats with pyometra (P < 0.001) compared with other groups. This was also true for PGF2α in pyometra, compared with cats treated either short- or long-term with MPA and cats during late diestrus (P < 0.001), anestrus (P < 0.01), and estrus and middiestrus (P < 0.05). Treatment with LPS and TNF-α combined stimulated PGE2 secretion in all groups compared with the control (P < 0.001 for endometria of cats during anestrus or middiestrus, cats treated short-term with MPA, and those with pyometra; P < 0.01 for endometria of cats treated long-term with MPA; and P < 0.05 for the endometria of cats during estrus and late diestrus). The combined treatment with LPS and TNF-α increased PGF2α secretion in the endometria of cats treated short-term with MPA (P < 0.001), during anestrus and pyometra (P < 0.01 for both), and estrus and middiestrus (P < 0.05 for both), compared with the control. Spontaneous secretion of prostaglandins was several times greater in the endometria of queens with pyometra, compared with other groups, which may further regulate the local inflammatory response. Data gathered from endometrial cell culture and endometrial organ culture lead to the conclusion that disturbances in prostaglandin release contribute to pyometra in cats.

Dynamics of Notch signalling in the mouse oviduct and uterus during the oestrous cycle

The oviduct and uterus undergo extensive cellular remodelling during the oestrous cycle, requiring finely tuned intercellular communication. Notch is an evolutionarily conserved cell signalling pathway implicated in cell fate decisions in several tissues. In the present study we evaluated the quantitative real-time polymerase chain reaction (real-time qPCR) and expression (immunohistochemistry) patterns of Notch components (Notch1-4, Delta-like 1 (Dll1), Delta-like 4 (Dll4), Jagged1-2) and effector (hairy/enhancer of split (Hes) 1-2, Hes5 and Notch-Regulated Ankyrin Repeat-Containing Protein (Nrarp)) genes in the mouse oviduct and uterus throughout the oestrous cycle. Notch genes are differentially transcribed and expressed in the mouse oviduct and uterus throughout the oestrous cycle. The correlated transcription levels of Notch components and effector genes, and the nuclear detection of Notch effector proteins, indicate that Notch signalling is active. The correlation between transcription levels of Notch genes and progesterone concentrations, and the association between expression of Notch proteins and progesterone receptor (PR) activation, indicate direct progesterone regulation of Notch signalling. The expression patterns of Notch proteins are spatially and temporally specific, resulting in unique expression combinations of Notch receptor, ligand and effector genes in the oviduct luminal epithelium, uterus luminal and glandular epithelia and uterine stroma throughout the oestrous cycle. Together, the results of the present study imply a regulatory role for Notch signalling in oviduct and uterine cellular remodelling occurring throughout the oestrous cycle.

Medical treatment for pyometra in dogs

Pyometra is a reproductive disorder very common in bitches over 8 years of age in which physiological effects of progesterone on the uterus play a major role. The traditional therapy for pyometra is ovariohysterectomy. The main advantage of ovariohysterectomy over medical management is that it is both curative and preventive for recurrence of pyometra. However, surgery is associated with the risk of anaesthesia and renders the bitch sterile. During the last 10 years, numerous medical treatments have been proposed to treat both open and closed cervix pyometra. The most effective medical treatment with minor side effects seems to be the repeated administration of aglepristone with or without the additional treatment with low doses of prostaglandins.

Oestrous cycle-dependent expression of Fas and Bcl2 family gene products in normal canine endometrium

During the oestrous cycle canine endometrium undergoes cyclical cellular proliferation, apoptosis and differentiation. To study the regulation of endometrial apoptosis and proliferation events the expression of apoptosis-related genes was analysed by real-time polymerase chain reaction and cellular expression of their proteins was identified through immunohistochemistry. Cellular apoptosis and proliferation events were detected by TdT-mediated dUTP-biotin nick end labeling (TUNEL) and proliferation marker Ki67 immunostaining, respectively. The highest proliferative index was observed in the follicular phase (all endometrial cellular components) and at early dioestrus (basal glands). This was associated with a low apoptotic index and a strong expression of anti- (Bcl2) and pro-apoptotic proteins (Fas, FasL, Bax). Subsequently (Days 11-45 of dioestrus), basal glandular epithelium experienced the highest apoptotic index, coincidental with a decrease of Bcl2 expression and a low ratio of Bcl2/Bax transcription. An increase in the apoptotic index of crypts, stromal and endothelial cells was observed at late dioestrus and the beginning of anoestrus. These results indicate that pro- and anti-apoptotic proteins regulate the balance between cell proliferation and death in the canine endometrium during the oestrous cycle. High Bcl2 expression in both the follicular and early dioestrous phases stimulate glandular proliferation and prevent apoptosis but, in the non-pregnant uterus, a decrease in Bcl2 expression together with an increase in pro-apoptotic proteins induces apoptosis of basal glandular epithelium cells.

In vivo notch signaling blockade induces abnormal spermatogenesis in the mouse

In a previous study we identified active Notch signaling in key cellular events occurring at adult spermatogenesis. In this study, we evaluated the function of Notch signaling in spermatogenesis through the effects of in vivo Notch blockade. Adult CD1 male mice were either submitted to a long term DAPT (?-secretase inhibitor) or vehicle treatment. Treatment duration was designed to attain one half the time (25 days) or the time (43 days) required to accomplish a complete cycle of spermatogenesis. Blockade of Notch signaling was depicted from decreased transcription of Notch effector genes. Notch signaling blockade disrupted the expression patterns of Notch components in the testis, induced male germ cell fate aberrations, and significantly increased germ cell apoptosis, mainly in the last stages of the spermatogenic cycle, and epididymis spermatozoa morphological defects. These effects were more pronounced following the 43 day than the 25 day DAPT treatment schedule. These results indicate a relevant regulatory role of Notch signaling in mammalian spermatogenesis.

Dynamics of Notch pathway expression during mouse testis post-natal development and along the spermatogenic cycle

The transcription and expression patterns of Notch pathway components (Notch 1–3, Delta1 and 4, Jagged1) and effectors (Hes1, Hes2, Hes5 and Nrarp) were evaluated (through RT-PCR and IHC) in the mouse testis at key moments of post-natal development, and along the adult spermatogenic cycle. Notch pathway components and effectors are transcribed in the testis and expressed in germ, Sertoli and Leydig cells, and each Notch component shows a specific cell-type and time-window expression pattern. This expression at key testis developmental events prompt for a role of Notch signaling in pre-pubertal spermatogonia quiescence, onset of spermatogenesis, and regulation of the spermatogenic cycle.