The expression and localization of Toll-like receptors 2, 4, 5 and 9 in the epididymis and vas deferens of a adult tom cats

Diversity of selected toll-like receptor genes in cheetahs (Acinonyx jubatus) and African leopards (Panthera pardus pardus)

The anthropogenic impact on wildlife is ever increasing. With shrinking habitats, wild populations are being pushed to co-exist in proximity to humans leading to an increased threat of infectious diseases. Therefore, understanding the immune system of a species is key to assess its resilience in a changing environment. The innate immune system (IIS) is the body's first line of defense against pathogens. High variability in IIS genes, like toll-like receptor (TLR) genes, appears to be associated with resistance to infectious diseases. However, few studies have investigated diversity in TLR genes in vulnerable species for conservation. Large predators are threatened globally including leopards and cheetahs, both listed as 'vulnerable' by IUCN. To examine IIS diversity in these sympatric species, we used next-generation-sequencing to compare selected TLR genes in African leopards and cheetahs. Despite differences, both species show some TLR haplotype similarity. Historic cheetahs from all subspecies exhibit greater genetic diversity than modern Southern African cheetahs. The diversity in investigated TLR genes is lower in modern Southern African cheetahs than in African leopards. Compared to historic cheetah data and other subspecies, a more recent population decline might explain the observed genetic impoverishment of TLR genes in modern Southern African cheetahs. However, this may not yet impact the health of this cheetah subspecies.

Expression of placental growth factor and a disintegrin and metalloprotease with a thrombospondin type motifs 1-4-8 during the three trimesters of rat pregnancy at the maternal-fetal interface

The functional roles of the a disintegrin and metalloprotease with a thrombospondin type motifs (ADAMTS) gene family in reproductive physiology, reproductive organs developments and adult reproductive health are still under investigation. The expression of the anti-angiogenic proteases ADAMTS-1, ADAMTS-4 and ADAMTS-8 in placental angiogenesis at various stages of pregnancy also remains unclear. The purpose of this study was therefore to determine the localization and expression of the ADAMTS-1, ADAMTS-4 and ADAMTS-8 proteins during the three stages of pregnancy in rats. Maternal-fetal tissue samples were collected on Days 5, 12 and 19 of each trimester, corresponding to the first, second and third trimesters. The expression of placental growth factor (PlGF) and ADAMTS-1, ADAMTS-4 and ADAMTS-8 at the maternal-fetal interface was examined using immunohistochemistry and western blot at three distinct phases of pregnancy. ADAMTS-1, ADAMTS-4 and ADAMTS-8 were detected in all three trimesters of pregnancy. The relative amount of PIGF increased in the first trimester and decreased significantly in the third trimester (p < 0.05). The expression of ADAMTS-1 and ADAMTS-4 was significantly higher in the second (p < 0.05) and third trimesters (p < 0.01) compared to the first trimester. However, no statistically significant change was observed in ADAMTS-8 expression between trimesters. The ADAMTS exhibiting the highest expression during the first trimester was ADAMTS8. These findings indicate that the expression of ADAMTS-1, ADAMTS-4 and ADAMTS-8 in the three different stages of rat pregnancy may be involved in the modulation of decidualization, morphogenesis and angiogenesis. Periodic changes in ADAMTS expression are thought to be regulated by gonadal steroids.

The abundance and localization of claudin-1 and -5 in the adult tomcats (Felis catus) testis, tubules rectus, rete testis, efferent ductules, and epididymis

Tight junctions (TJ) are the anatomical component of blood-testis (BTB) and blood-epididymis (BEB) barriers and contain many proteins, including claudins. The presence of claudins in domestic cat testis and epididymis has not been previously described. This study aimed to determine whether claudin-1 and claudin-5 participate in the structure of BTB and BEB and whether their amounts differ between the testis and epididymal segments of adult cats, using Western blotting (WB) and immunohistochemistry. WB results demonstrated that claudin-1 was significantly lower in the testis than in all epididymal segments and higher in the corpus epididymis than in the cauda, while claudin-5 in the testis was significantly lower than in the caput and corpus. Claudin-1 was absent at the Sertoli-Sertoli junctions, while claudin-5 was detected at the level of the BTB during stages I and VIII. Both claudins were observed in the pachytene spermatocytes and the developing acrosome of the round and elongating spermatids. Claudin-5 was also detected in the cytoplasm of some spermatogonia, Sertoli cells, and late spermatid acrosome. In the epididymal segments, both claudins were localized to the area of the tight junctions and along the entire length of the lateral plasma membranes of adjacent principal cells and between principal and basal cells. These results may indicate that in the domestic cat, claudin-1 and -5 participate as both tight junction proteins and adhesion molecules in the BEB's structure, claudin 5 is a component of the BTB, and both proteins may be involved in postmeiotic germ cell development, especially acrosome development.

Variation in immuno-reproductive milieu of testis in Clarias magur from pre-spawning to spawning phase: An indication towards non-canonical role of immune elements in testes

Immune mechanisms are major players in ensuring the normal functioning of testicular functions. However, apart from their role in active defence against pathogens, prior studies have also suggested a possibility for reproduction-related (non-immune) functions of certain immune elements. This study employs a comparative transcriptomics approach followed by network analysis for tracking the variation in the immuno-reproductive milieu of Clarias magur testis in spawning versus pre-spawning phase. The results show a significant modulation of both reproduction and immune-relevant genes in spawning versus pre-spawning phase. The functional enrichment of the upregulated reproduction-relevant gene network also shows immune-related biological processes which indicates a probability of involvement of these candidates in spermatogenesis-related events for switching from pre-spawning to spawning phase. The upregulated immune network is highly dense with 40 hubs, 10 cluster sub-networks and 142 functionally enriched pathways in comparison to its downregulated counterpart with only 5 hubs, 1 cluster and 1 enriched pathway. These findings indicate that the synchronisation in modulation of both reproductive and immune-related factors is critical for progression of testicular events guiding the switch from pre-spawning to spawning phase. The reproductive phase-dependent variation in plasma sex steroid levels and the selected genes for quantitative PCR also corroborated this hypothesis. The study also serves as a preliminary screening step for probable immune candidates that may be involved in reproductive functions of testis in addition to defence.

Differential gene expression and hallmarks of stemness in epithelial cells of the developing rat epididymis

Epididymal development can be subdivided into three phases: undifferentiated, a period of differentiation, and expansion. The objectives of this study were (1) to assess gene expression profiles in epididymides, (2) predict signaling pathways, and (3) develop a novel 3D cell culture method to assess the regulation of epididymal development in vitro. Microarray analyses indicate that the largest changes in differential gene expression occurred between the 7- to 18-day period, in which 1452 genes were differentially expressed, while 671 differentially expressed genes were noted between days 18 and 28, and there were 560 differentially expressed genes between days 28 and 60. Multiple signaling pathways were predicted at different phases of development. Pathway associations indicated that in epididymides of 7- to 18-day old rats, there was a significant association of regulated genes implicated in stem cells, estrogens, thyroid hormones, and kidney development, while androgen- and estrogen-related pathways were enriched at other phases of development. Organoids were derived from CD49f + columnar cells from 7-day old rats, while no organoids developed from CD49f^- cells. Cells cultured in an epididymal basal cell organoid medium versus a commercial kidney differentiation medium supplemented with DHT revealed that irrespective of the culture medium, cells within differentiating organoids expressed p63, AQP9, and V-ATPase after 14 days of culture. The commercial kidney medium resulted in an increase in the number of organoids positive for p63, AQP9, and V-ATPase. Together, these data indicate that columnar cells represent an epididymal stem/progenitor cell population.

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.

Expression profile of Toll-like receptor 4 in rat testis and epididymis throughout postnatal development

Toll-like receptors (TLRs) belonging to pattern recognition receptors are involved in maintaining testicular and epididymal immune homeostasis. The purpose of the current study was to investigate TLR4 expression in rat testis and epididymis throughout postnatal development. Weak staining was detected in peritubular myoid cells and immature Sertoli cells while no staining was observed in gonocytes during prepubertal period. However, TLR4 expression began to appear in spermatocytes in pubertal period and gradually increased in spermatids. An intense staining was observed in steps 5-19 spermatids in post pubertal and mature periods. Similarly, TLR4 expression in the testes steadily increased from pubertal period to mature period. Puberty also caused a significant increase in TLR4 expression in epididymis. TLR4 expression in cauda epididymis was lower as compared to those of other epididymal segments. The majority of epididymal epithelial cells exhibited apical TLR4 expression, whereas basal cells showed intense intracytoplasmic immunoreaction. We detected an intense staining in epididymal smooth muscle cells. The expression levels of TLR4 showed dynamic changes in both spermatogenic cells, and entire testicular and epididymal tissues during postnatal development. These results suggest that TLR4 expression contributes not only to inflammation but also to the development of spermatogenic cells.

Effects of Diets Enriched in Linseed and Fish Oil on the Expression Pattern of Toll-Like Receptors 4 and Proinflammatory Cytokines on Gonadal Axis and Reproductive Organs in Rabbit Buck

Infections of the genital tract can perturb the fertility in humans and animals. Pathogen recognition and activation of innate immunity onset through the pattern recognition receptor activation, such as Toll-like receptor 4 (TLR4), leading to the production of proinflammatory cytokines and mediators. TLR4 is expressed both on leukocytes and nonimmune cells. Rabbit TLR4 shows great similarity to its human counterpart. Moreover, the TLR4 signalling pathway could be modulated by long-chain polyunsaturated fatty acids (LC-PUFA). The objectives of this study were (i) to determine the expression levels of TLR4 and proinflammatory cytokines in the reproductive hypothalamic-gonadal axis of the male rabbit and (ii) to evaluate if the n-3 PUFA-enriched diets can modify their expression levels in the tissues and LC-PUFA profiles in seminal plasma. Fifteen rabbit bucks (n = 5/experimental group) were fed with different diets: commercial standard (group C), rich in extruded linseed (10%, group L), and in fish oil (3%, group FO) for 110 days. TLR4, TNF-α, and IL-1β mRNA were ubiquitously expressed throughout the hypothalamic-gonadal axis. However, TLR4 mRNA expression was lower in the hypothalamus than the epididymis (P < 0.01), seminal vesicles (P < 0.01), and pituitary gland (P < 0.05). Dietary enrichment in PUFA did not modify the gene expression profile nor the histological characteristics of the tissues. Conversely in seminal plasma, rabbits fed with L and FO had lower n-6 (P < 0.05), LC-PUFA n-6 (P < 0.05), and n-6/n-3 ratio (P < 0.05) but higher n-3 (P < 0.001) and LC-PUFA n-3 (P < 0.01) compared to the control group. Our study builds a map of the gene expression of TRL4 and proinflammatory cytokines in the reproductive hypothalamic-gonadal axis of the male rabbit, fundamental step for understanding the immune defence mechanisms. Diets enriched in LC-PUFA did not affect basal gene expression but modulated sperm fatty acid composition. Finally, rabbit may be an excellent animal model to study the relationship between inflammation and infertility, and the nutritional modulation of immune functions.

Abundances and localizations of Claudin-1 and Claudin-5 in the domestic cat (Felis catus) ovary during the estrous cycle

Claudins (CLDNs) are major Ca²⁺-independent cell adhesion molecules functioning at tight junctions (TJ). The presence and localization of cell adhesion molecules are important for understanding the mechanisms associated with follicular and luteal development in the ovary. In this study, there was an examination of whether CLDN-1 and CLDN-5 are present in a cell- and stage-specific manner during follicular and luteal development in the domestic cat ovary using immunohistochemistry and Western blot analysis. While results from immunoblot analyses revealed there were relatively similar abundances of CLDN-5 protein in three phases of the ovarian cycle, the abundance of CLDN-1 in the luteal phase was greater than those measured in the follicular and anestrous phases (P < 0.01). Results with immunohistochemistry indicate CLDN-1 and -5 are mainly localized in the cell nuclei and cytoplasm of all tissues of the cat ovary. In follicles, throughout the development from primordial to large antral follicles, CLDN-1 and -5 were present in oocytes, and the granulosa and theca cell layers. In follicles at all stages of atresia, there were cell-type and stage-specific protein distributions with immunostaining present in granulosa, thecal interstitial, and fibroblast-like cells. In corpora lutea, both small and large luteal cells stained positively for both claudins. In conclusion, the specific presence and localization patterns of CLDN-1 and -5 in the cat ovary is suggestive that these TJ proteins could have local functions in the regulation of most ovarian functions such as follicle development and atresia, ovulation, and corpus luteum formation and regression.

Tlr1-13, Nod1/2 and antimicrobial gene expression in the epididymis and testis of rats with alloxan-induced diabetes

Pattern recognition receptors (PRRs) such as toll-like receptors (TLRs) and nuclear oligomerization domain (NOD) receptors along with antimicrobial proteins and peptides (AMPs) are crucial for innate immunity. The pathology of insulin-dependent diabetes mellitus is associated with the disrupted expression of TLRs, NODs and AMPs in the kidney, lungs and other organs. However, such a relation in the male reproductive tract is not yet investigated. In this study, we analysed the expression pattern of Tlr1-13, Nod1/2 receptors and AMPs (β-defensins and defensin-like proteins of the Sperm-Associated Antigen 11 (Spag11) family) in the male reproductive tissues (caput, cauda and testis) obtained from diabetic or insulin-treated diabetic or untreated control rats. Alterations in the expression pattern of Tlr1-13, Nod 1/ 2, Defb1, 2, 21, 24, 27, 30 and Spag11a/ c/ t were observed under diabetic conditions. Administration of insulin to diabetic rats could modulate the expression pattern of only some these genes. Results of our study indicate perturbed gene expression profile of Tlrs, Nod1/2, Defbs and Spag11 isoforms in the epididymis and testis of diabetic rats, and this could be one of the important reasons for the increased risk of infections in the male genital tract.