Immunohistochemical studies on the bovine lactating mammary gland (Bos taurus)

Bovine milk-derived cells express transcriptome markers of pluripotency and secrete bioactive factors with regenerative and antimicrobial activity

The bovine mammary stem/progenitor cell secretome stimulates regeneration in vitro and contains proteins associated with antimicrobial defense. This has led to the exploration of the secretome as a biologic treatment for mastitis, a costly inflammation of the udder commonly caused by bacteria. This study reports on a population of bovine mammary stem/progenitor cells isolated non-invasively from milk (MiDCs). MiDCs were characterized by immunophenotyping, mammosphere formation assays, and single cell RNA sequencing. They displayed epithelial morphology, exhibited markers of mammary stem/progenitor cells, and formed mammospheres, like mammary gland tissue-isolated stem/progenitor cells. Single cell RNA sequencing revealed two sub-populations of MiDCs: epithelial cells and macrophages. Functionally, the MiDC secretome increased fibroblast migration, promoted angiogenesis of endothelial cells, and inhibited the growth of mastitis-associated bacteria, including antibiotic-resistant strains, in vitro. These qualities of MiDCs render them a source of stem cells and stem cell products that may be used to treat diseases affecting the dairy industry, including mastitis.

Immunohistochemical Studies of αSMA in the Epididymis of African Four-Toed Hedgehog (Atelerix albiventris)

The epididymis plays an important role in sperm maturation, storage, transport and in the secretion of enzymes and proteins into the tubular lumen. In this study, we examined the histology, microstereology and immunohistochemical localization of alpha smooth muscle (αSMA) in the three regions of the epididymis of the African four-toed hedgehog (Atelerix albiventris). Ten adult males were captured from the wild in Ibadan, Nigeria, between May and October, 2016. The animals were euthanized and the epididymis (caput, corpus and cauda regions) were retrieved and fixed in buffered neutral formalin ahead of the paraffin technique, following standard procedures. The duct of the epididymis was lined by pseudostratified columnar epithelium comprising basal, principal and apical cells as well as intraepithelial lymphocytes in proximity to basal cells. The principal cells, the major cells encountered within the epididymal epithelium of the animal, decreased in population from the caput to the cauda epididymidis while the apical cells were more abundant in the cauda epididymidis. Positive reactions to αSMA were observed in the peritubular muscular coat of the epididymal duct as well as blood vessels across the three regions of the epididymis with the caput and cauda epididymidis showing stronger positive reactions compared to the corpus epididymidis. This study demonstrated that the histology, microstereology as well as the cellular constituents of the epididymal duct of the Atelerix albiventris are similar to those of other mammals with a slight variation. It has also highlighted variation in the localization of αSMA across the regions of the epididymis of the animal.

Immunohistochemical Study of the Stromal Cells in the Lactating Bovine Mammary Gland

The bovine mammary gland is a special gland characterized by high secretory activity. During lactation the cellular and fibrous components of the interstitial tissue septa are exposed to store accumulated secretory products. The aim of this study was to find and study the cells in the stroma of the bovine lactating mammary gland. For this purpose, the immunohistochemical methods and antibodies against the smooth muscle actin, vimentin, and desmin were used. The myoepithelial cells (MEC) which stained with smooth muscle actin (SMA), were found supporting the secretory units and the intralobular ducts. Coexpression of the SMA and desmin were found in the smooth muscle cells of the blood vessels. The fibroblasts (myofibroblasts) and free cells positive to vimentin were located in the connective tissue septa. The results of this study on the mammary glands indicated that smooth muscle cells (SMC) were altered in the lactating mammary gland, with additional cells such as fibroblasts (myofibroblasts) participated in the storage and after milk let-down they allowed the mammary glands to return to their original state.

Sinus-like dilatations of the mammary milk ducts, Ki67 expression, and CD3-positive T lymphocyte infiltration, in the mammary gland of wild European rabbits during pregnancy and lactation

Sinus-like dilatations of the mammary duct are recognisable in the mammary gland of pregnant and lactating wild European rabbits. These dilatations exhibit a bilaminar epithelial lining, with luminal epithelial cells expressing basal and lateral E-cadherin. Occasional binucleated mammary epithelial cells are present in the luminal layer. Underlying the luminal epithelial cells is a basal layer of cytokeratin 14-positive cells, supported by a thin layer of fibrous tissue. Multi-segmental epithelial proliferation, as indicated by Ki67 expression, is apparent in the luminal epithelial cells, suggesting a capacity for division during pregnancy and lactation. CD3-positive T lymphocytes are present both intraepithelially, suggesting exocytosis, and in foci subjacent to the ductular epithelium. We consider that sinus-like dilatations of the mammary duct may have the potential to give rise to a subset of the mammary gland neoplasms classified as ductal in origin. Milk accumulation in these sinus-like dilatations is likely to provide a niche for bacterial replication in cases of mastitis in rabbits. These structures are an important component of the innate immune system of the mammary gland, both as a physical barrier and as an interface between the milk and mammary immune cells.

The secretome from bovine mammosphere-derived cells (MDC) promotes angiogenesis, epithelial cell migration, and contains factors associated with defense and immunity

Treatment of bovine mastitis with intramammary antibiotics is common, yet several concerns exist including failed efficacy for individual hosts or pathogens and the inability of approved drugs to revert mastitis-induced tissue damage to healthy tissue capable of returning to full milk production. These issues, in addition to aspects of public health such as accidental antibiotic residues in saleable milk and the potential for antimicrobial resistance, support the need to find alternative therapies for this costly disease. This study shows that the secretome, or collective factors, produced by mammosphere-derived cells (MDC) promotes angiogenesis, epithelial cell migration, and contains proteins associated with immunity and defense; all of which are necessary for healing damaged mammary gland tissue. Furthermore, we found that the MDC secretome remains effective after freezing and thawing, enhancing its therapeutic potential. Our results provide a foundation for further characterization of the individual secreted factors and the rationale for using the MDC secretome as a complementary treatment for bovine mastitis.

Transcriptional profiling of mammary gland in Holstein cows with extremely different milk protein and fat percentage using RNA sequencing

Background

Recently, RNA sequencing (RNA-seq) has rapidly emerged as a major transcriptome profiling system. Elucidation of the bovine mammary gland transcriptome by RNA-seq is essential for identifying candidate genes that contribute to milk composition traits in dairy cattle.

Results

We used massive, parallel, high-throughput, RNA-seq to generate the bovine transcriptome from the mammary glands of four lactating Holstein cows with extremely high and low phenotypic values of milk protein and fat percentage. In total, we obtained 48,967,376–75,572,578 uniquely mapped reads that covered 82.25% of the current annotated transcripts, which represented 15549 mRNA transcripts, across all the four mammary gland samples. Among them, 31 differentially expressed genes (p < 0.05, false discovery rate q < 0.05) between the high and low groups of cows were revealed. Gene ontology and pathway analysis demonstrated that the 31 differently expressed genes were enriched in specific biological processes with regard to protein metabolism, fat metabolism, and mammary gland development (p < 0.05). Integrated analysis of differential gene expression, previously reported quantitative trait loci, and genome-wide association studies indicated that TRIB3, SAA (SAA1, SAA3, and M-SAA3.2), VEGFA, PTHLH, and RPL23A were the most promising candidate genes affecting milk protein and fat percentage.

Conclusions

This study investigated the complexity of the mammary gland transcriptome in dairy cattle using RNA-seq. Integrated analysis of differential gene expression and the reported quantitative trait loci and genome-wide association study data permitted the identification of candidate key genes for milk composition traits.

Stem cell research: a novel boulevard towards improved bovine mastitis management

The dairy industry is a multi-billion dollar industry catering the nutritional needs of all age groups globally through the supply of milk. Clinical mastitis has a severe impact on udder tissue and is also an animal welfare issue. Moreover, it significantly reduces animal value and milk production. Mammary tissue damage reduces the number and activity of epithelial cells and consequently contributes to decreased milk production. The high incidence, low cure rate of this highly economic and sometimes deadly disease is an alarming for dairy sector as well as policy makers. Bovine mammary epithelial cells (MECs) and their stem cells are very important in milk production and bioengineering. The adult mammary epithelium consists of two main cell types; an inner layer of luminal epithelial cells, which produce the milk during lactation, and an outer layer of myoepithelial cells resting on a basement membrane, which are responsible for pushing the milk through the ductal network to the teat cistern. Inner layer of columner/luminal cells of bovine MECs, is characterized by cytokeratin18, 19 (CK18, CK19) and outer layer such as myoepithelial cells which are characterized by CK14, α-smooth muscle actin (α-SMA) and p63. Much work has been done in mouse and human, on mammary gland stem cell research, particularly in cancer therapy, but stem cell research in bovine is still in its infancy. Such stem/progenitor cell discoveries in human and mouse mammary gland bring some hope for application in bovines. These progenitors may be therapeutically adopted to correct the structural/cytological defects in the bovine udder due to mastitis. In the present review we focused on various kinds of stem/progenitor cells which can have therapeutic utility and their possibilities to use as a potential stem cell therapy in the management of bovine post-mastitis damage in orders to restore milk production. The possibilities of bovine mammary stem cell therapy offers significant potential for regeneration of tissues that can potentially replace/repair diseased and damaged tissue through differentiation into epithelial, myoepithelial and/or cuboidal/columnar cells in the udder with minimal risk of rejection and side effects.

Mammary analogue secretory carcinoma of salivary glands is a lipid-rich tumour, and adipophilin can be valuable in its identification

AIMS

Mammary analogue secretory carcinoma (MASC) of salivary glands shows morphological similarities to milk-secreting mammary epithelial cells. The aim of this study was to analyse the immunohistochemical expression of adipophilin (a component of milk lipid globule membranes) and of proteins related to secretory mechanisms (STAT5a and mammaglobin) in MASC and other salivary tumours.

METHODS AND RESULTS

Ten cases of MASC (all with ETV6 translocation) and 83 other salivary carcinomas were studied. In all MASC cases, adipophilin stained numerous large lipid droplets. These droplets were minute in other salivary carcinomas, except for sebaceous carcinoma. Overexpression of STAT5a was detected in all MASC cases, but only occasionally in other carcinomas. Mammaglobin expression occurred frequently in MASC (70% of cases), whereas, in other carcinomas, it was uncommon and limited. Only MASC showed cytoplasmic reactivity for p63, particularly in papillary-cystic areas. Positivity for S100, vimentin and high molecular weight keratin was observed in 100% of MASC cases.

CONCLUSIONS

MASC is a lipid-rich tumour containing large lipid droplets covered by adipophilin. This finding can be included among its defining immunohistochemical features, and possibly represents lactation-like secretory differentiation. Strong expression of STAT5a and cytoplasmic p63 in MASC reinforces this hypothesis.

Recombinant bovine S100A8 and A9 enhance IL-1β secretion of interferon-gamma primed monocytes

Calgranulin A (S100A8) and B (S100A9) are found at high levels in inflamed tissue and have been associated with acute and chronic inflammatory disorders. Calgranulins are discussed as damage-associated molecular patterns (DAMPs). To analyze the role of calgranulins for inflammatory responses, bovine S100A8 and S100A9 were cloned, successfully expressed and FPLC-purified. Both molecules did not induce NF-κB activation in boTLR4-transfected HEK293 cells and stimulation of bovine monocytes with both proteins did not result in interleukin 1β (IL-1β) secretion or an upregulated mRNA expression of selected genes (IL1B, TNF, CXCL8, IL10, IL12). However, Interferon γ (IFN-γ) primed bovine monocytes released significantly higher amounts of IL-1β after stimulation with S100A8, S100A9, and co-stimulation with adenosine triphosphate (ATP). In IL-4/IL-13-primed monocytes, the IL-1β release was completely abrogated. The results imply that TLR4/MyD88/NF-κB-independent S100A8/A9-mediated activation of the inflammasome in cattle is favored in a Th1 environment and that S100A8 and S100A9 act as a DAMP in cattle.

Immunohistochemical studies on the poll gland of the dromedary camel (Camelus dromedarius) during the rutting season

The poll glands are subcutaneous exocrine glands located on the back of the neck behind the ears in male camels. The function of poll glands is not well known, though they are thought to play a role during the rutting season. The presence, location and degree of immunolocalization of microfilaments and intermediate filament systems: actin and cytokeratins (Cks) and also S100 protein were studied in the poll glands in sexually mature one-humped camels during the rutting season. These proteins were variably expressed between the epithelia, perialveolar, interalveolar tissue and the periductal tissue. Strong α-smooth muscle actin (α-SMA) immunoreactivity (IR) was displayed by the perialveolar myoepithelial cells, periductal and vascular smooth muscle cells (SMCs), but not in the epithelial cells. Cytokeratin (Ck)-IR was strong in the epithelial lining of the secretory alveoli and excretory ducts, however, the apical blebs of the secretory cells were almost negative. Weak to moderate Ck-IR was observed in the perialveolar myoepithelial cells, but not in the interalveolar tissue or endothelial cells. S100 protein was expressed variably in the epithelial lining of the secretory alveoli. S100-IR was more obvious in the supranuclear region and the apical blebs. Variable reaction was observed in the perialveolar myoepithelial cells, periductal and interductal tissue and endothelial cells.

Cell hierarchy and lineage commitment in the bovine mammary gland

The bovine mammary gland is a favorable organ for studying mammary cell hierarchy due to its robust milk-production capabilities that reflect the adaptation of its cell populations to extensive expansion and differentiation. It also shares basic characteristics with the human breast, and identification of its cell composition may broaden our understanding of the diversity in cell hierarchy among mammals. Here, Lin⁻ epithelial cells were sorted according to expression of CD24 and CD49f into four populations: CD24^medCD49f^pos (putative stem cells, puStm), CD24^negCD49f^pos (Basal), CD24^highCD49f^neg (putative progenitors, puPgt) and CD24^medCD49f^neg (luminal, Lum). These populations maintained differential gene expression of lineage markers and markers of stem cells and luminal progenitors. Of note was the high expression of Stat5a in the puPgt cells, and of Notch1, Delta1, Jagged1 and Hey1 in the puStm and Basal populations. Cultured puStm and Basal cells formed lineage-restricted basal or luminal clones and after re-sorting, colonies that preserved a duct-like alignment of epithelial layers. In contrast, puPgt and Lum cells generated only luminal clones and unorganized colonies. Under non-adherent culture conditions, the puPgt and puStm populations generated significantly more floating colonies. The increase in cell number during culture provides a measure of propagation potential, which was highest for the puStm cells. Taken together, these analyses position puStm cells at the top of the cell hierarchy and denote the presence of both bi-potent and luminally restricted progenitors. In addition, a population of differentiated luminal cells was marked. Finally, combining ALDH activity with cell-surface marker analyses defined a small subpopulation that is potentially stem cell- enriched.