Peripheral T cell activation and deletion induced by transfer of lymphocyte subsets expressing endogenous or exogenous mouse mammary tumor virus.

Murine T cell reactivity with products of the minor lymphocyte stimulatory (Mls) locus correlates with the expression of particular variable (V) domains of the T cell receptor (TCR) beta chain. It was recently demonstrated that Mls antigens are encoded by an open reading frame (ORF) in the 3' long terminal repeat of either endogenous or exogenous mouse mammary tumor virus (MMTV). Immature thymocytes expressing reactive TCR-V beta domains are clonally deleted upon exposure to endogenous Mtv's. Mature T cells proliferate vigorously in response to Mls-1a (Mtv-7) in vivo, but induction of specific anergy and deletion after exposure to Mtv-7-expressing cells in the periphery has also been described. We show here that B cells and CD8+ (but not CD4+) T cells from Mtv-7+ mice efficiently induce peripheral deletion of reactive T cells upon transfer to Mtv-7- recipients, whereas only B cells stimulate specific T cell proliferation in vivo. In contrast to endogenous Mtv-7, transfer of B, CD4+, or CD8+ lymphocyte subsets from mice maternally infected with MMTV(SW), an infectious homologue of Mtv-7, results in specific T cell deletion in the absence of a detectable proliferative response. Finally, we show by secondary transfers of infected cells that exogenous MMTV(SW) is transmitted multidirectionally between lymphocyte subsets and ultimately to the mammary gland. Collectively our data demonstrate heterogeneity in the expression and/or presentation of endogenous and exogenous MMTV ORF by lymphocyte subsets and emphasize the low threshold required for induction of peripheral T cell deletion by these gene products.

MHC class II hierarchy of superantigen presentation predicts efficiency of infection with mouse mammary tumor virus.

Superantigens (SAgs) encoded by infectious mouse mammary tumor viruses (MMTVs) play a crucial role in the viral life cycle. Their expression by infected B cells induces a proliferative immune response by SAg-reactive T cells which amplifies MMTV infection. This response most likely ensures stable MMTV infection and transmission to the mammary gland. Since T cell reactivity to SAgs from endogenous Mtv loci depends on MHC class II molecules expressed by B cells, we have determined the ability of MMTV to infect various MHC congenic mice. We show that MHC class II I-E+ compared with I-E- mouse strains show higher levels of MMTV infection, most likely due to their ability to induce a vigorous SAg-dependent immune response following MMTV encounter. Inefficient infection is observed in MHC class II I-E- mice, which have been shown to present endogenous SAgs poorly. Therefore, during MMTV infection the differential ability of MHC class II molecules to form a functional complex with SAg determines the magnitude of the proliferative response of SAg-reactive T cells. This in turn influences the degree of T cell help provided to infected B cells and therefore the efficiency of amplification of MMTV infection.

Retroviral infection of neonatal Peyer's patch lymphocytes: the mouse mammary tumor virus model.

Mouse mammary tumor virus is known to infect newborn mice via mother's milk. A proposed key step for viral spread to the mammary gland is by the infection of lymphocytes. We show here that although in suckling mice retroviral proteins are found in all epithelial cells of the gut, viral DNA is exclusively detectable in the Peyer's patches. As early as 5 d after birth the infection leads to a superantigen response in the Peyer's patches but not in other lymphoid organs draining the intestine. Viral DNA can be detected before the superantigen response and becomes first evident in the Peyer's patches followed by mesenteric lymph nodes and finally all lymphoid organs.

Ectodysplasin/NF-κB Promotes Mammary Cell Fate via Wnt/β-catenin Pathway.

Mammary gland development commences during embryogenesis with the establishment of a species typical number of mammary primordia on each flank of the embryo. It is thought that mammary cell fate can only be induced along the mammary line, a narrow region of the ventro-lateral skin running from the axilla to the groin. Ectodysplasin (Eda) is a tumor necrosis factor family ligand that regulates morphogenesis of several ectodermal appendages. We have previously shown that transgenic overexpression of Eda (K14-Eda mice) induces formation of supernumerary mammary placodes along the mammary line. Here, we investigate in more detail the role of Eda and its downstream mediator transcription factor NF-κB in mammary cell fate specification. We report that K14-Eda mice harbor accessory mammary glands also in the neck region indicating wider epidermal cell plasticity that previously appreciated. We show that even though NF-κB is not required for formation of endogenous mammary placodes, it is indispensable for the ability of Eda to induce supernumerary placodes. A genome-wide profiling of Eda-induced genes in mammary buds identified several Wnt pathway components as potential transcriptional targets of Eda. Using an ex vivo culture system, we show that suppression of canonical Wnt signalling leads to a dose-dependent inhibition of supernumerary placodes in K14-Eda tissue explants.

Survival analysis of female dogs with mammary tumors after mastectomy: epidemiological, clinical and morphological aspects

Abstract: Mammary gland tumors are the most common type of tumors in bitches but research on survival time after diagnosis is scarce. The purpose of this study was to investigate the relationship between survival time after mastectomy and a number of clinical and morphological variables. Data was collected retrospectively on bitches with mammary tumors seen at the Small Animal Surgery Clinic Service at the University of Brasília. All subjects had undergone mastectomy. Survival analysis was conducted using Cox's proportional hazard method. Of the 139 subjects analyzed, 68 died and 71 survived until the end of the study (64 months). Mean age was 11.76 years (SD=2.71), 53.84% were small dogs. 76.92% of the tumors were malignant, and 65.73% had both thoracic and inguinal glands affected. Survival time in months was associated with age (hazard rate ratios [HRR] =1.23, p-value =1.4x10-4), animal size (HRR between giant and small animals =2.61, p-value =0.02), nodule size (HRR =1.09, p-value =0.03), histological type (HRR between solid carcinoma and carcinoma in a mixed tumor =2.40, p-value =0.02), time between diagnosis and surgery (TDS, with HRR =1.21, p-value =2.7x10-15), and the interaction TDS*follow-up time (HRR =0.98, p-value =1.6x10-11). The present study is one of the few on the subject matter. Several important covariates were evaluated and age, animal size, nodule size, histological type, TDS and TDS*follow up time were identified as significantly associated to survival time.

c-erbB-2 expression and nuclear pleomorphism in canine mammary tumors

The objective of the present investigation was to study the expression of c-erbB-2 and MIB-1 and try to associate them with morphological features of the cell such as nuclear pleomorphism, mitotic count and histological grade in a series of 70 canine mammary gland tumors, 22 of them benign and 48 malignant. Tumors were collected at the Veterinary Hospital of UFMG (Brazil) and the Veterinary Faculty of Porto University (Portugal). c-erbB-2 expression was determined according to the guidelines provided by the manufacturer of the HercepTest system and nuclear pleomorphism, mitotic count and histological grade according the Elston and Ellis grading system. The HercepTest is the FDA-approved in vitro diagnostic test marketed by Dako. It is a semi-quantitative immunohistochemical assay used to determine overexpression of HER2 protein (human epidermal growth factor receptor) in breast cancer tissue. MIB-1 expression was also evaluated in 28 malignant tumors. Seventeen (35.4%) of the malignant tumors were positive for c-erbB-2 expression, which was positively associated with nuclear pleomorphism (P < 0.0001), histological grade (P = 0.0017) and mitotic count (P < 0.05). Nuclear pleomorphism also showed a positive association with MIB-1 index (P < 0.0001). These results suggest that some of the biological and morphological characteristics of the tumor are associated in canine mammary gland tumors, as also reported for human breast cancer. It was also possible to show that the immunoexpression of c-erbB-2 can be a factor in mammary carcinogenesis. This fact opens the possibility of using anti-c-erbB-2 antibodies in the treatment of canine mammary tumors.

Morphological changes induced by testosterone in the mammary glands of female Wistar rats

Increased levels of androgens in postmenopausal women are considered to be a risk factor for breast cancer. Testosterone, alone or in combination with estrogen, induces epithelial dysplasia and mammary tumors in Noble rats. Since this model of hormone-induced neoplasia has not been reported in other rat strains, we studied the effect of testosterone on the mammary gland morphology of female Wistar rats. Sixty adult, non-castrated, female Wistar rats were implanted in the dorsum midline with a silicone tube containing 50 mg testosterone (testosterone propionate in 30 animals and non-esterified testosterone in the remaining 30 animals) and 20 additional animals were implanted with empty tubes and used as control. Five animals per group were killed 30, 60, 90, 120, 150, and 180 days after implantation, and the mammary glands were dissected, fixed and embedded in paraffin. Histological sections were then stained with hematoxylin and eosin and picrosyrius red for collagen visualization. Morphological and morphometric analysis demonstrated ductal proliferation and acinotubular differentiation with secretory activity in all treated animals, peaking at 90 days of androgen exposure. After 90 days the proliferation of acinar epithelial cells was evident, but there was a progressive reduction of secretory differentiation and an increase in intralobular collagen fibers. There was no morphological evidence of dysplastic changes or other pre-neoplastic lesions. Testosterone treatment applied to adult, non-castrated female Wistar rats induced a mammary gland hyperplasia resembling the lactating differentiation, with progressive reduction in secretory differentiation.

The influence of dietary fatty acid composition on N-ethyl-Nnitrosourea-induced mammary tumour incidence in the rat and on the composition of inositol- and ethanolamine-phospholipids of normal and tumour mammary tissue

This study has investigated the influence of dietary fatty acid composition on mammary tumour incidence in N-ethyl-N-nitrosourea (ENU)-treated rats and has compared the susceptibility to dietary fatty acid modification of the membrane phospholipids phosphatidyliuositol (PI) and phosphatidylethanolamine (PE) from normal and tumour tissue of rat mammary gland. The incidence of mammary tumours was significantly lower in fish oil- (29%), compared with olive oil- (75%; P < 0.04) but not maize oil- (63%; P < 0.1) fed animals. No differences in PI fatty acid composition were found in normal or tumour tissue between rats fed on maize oil, olive oil or fish oil in diets from weaning. When normal and tumour tissue PI fatty acids were compared, significantly higher amounts of stearic acid (18:O) were found in tumour than normal tissue in rats given olive oil (P < 0.05). A similar trend was found in animals fed on maize oil, although differences between normal and tumour tissue did not reach a level of statistical significance (P < 0.1). In mammary PE, maize oil-fed control animals had significantly higher levels of linoleic acid (18:2n-6) than either olive oil- or fish oil-fed animals (P < 0.05, both cases) and levels of arachidonic acid were also higher in maize oil- compared with fish oil-fed animals (P < 0.05). In tumourbearing animals no differences in PE fatty acid composition were found between the three dietary groups. When normal and tumour tissue PE fatty acids were compared, significantly lower amounts of liuoleic acid (18:2n-6; P < 0.01) and significantly greater amounts of arachidonic acid (20:4n-6; P < 0.05) were found in tumour than normal tissue of rats fed on maize oil. The present study shows that the fatty acid composition of PI from both normal and tumour tissue of the mammary gland is resistant to dietary fatty acid modification. The PE fraction is more susceptible to dietary modification and in this fraction there is evidence of increased conversion of linoleic acid to arachidonic acid in tumour compared with normal tissue. Lower tumour incidence rates in rats given fish oils may in part be due to alteration in prostanoid metabolism secondary to displacement of arachidonic acid by eicosapentaenoic acid, but PE rather than PI would appear to be the most likely locus for diet-induced alteration in prostanoid synthesis in this tissue. Effects of dietary fatty acids other than on the balance of n-6 and n-3 fatty acids, and on prostanoid metabolism, should also be considered. The significance of increased stearic acid content of PI in tumours of olive oil-fed animals and the possible influence of dietary fatty acids on the capacity for stearic acid accumulation requires further study.

Lymphatic drainage on healthy and neoplasic mammary glands in female dogs: Can it really be altered?

The purpose of this research was to study the mammary lymphatic drainage under a macroscopic and mesoscopic view, comparing the vascular pattern of healthy and neoplasic mammary glands injected with drawing ink alcoholic and fluorescein solutions, in 46 mongrel female dogs. The results pointed out that the thoracic gland is drained by the axillary lymph centre, but in mammary neoplasia either superficial cervical or ventral thoracic lymph centres can be involved. Cranial and caudal abdominal glands may be drained by the axillary, inguinofemoral and popliteal lymph centres. However, the popliteal drainage is specific for the healthy caudal abdominal mammary gland. The inguinal gland can be drained by both inguinofemoral and popliteal lymph centres in both neoplasic and healthy conditions. Regarding the mammary lymphatic communications, this research demonstrated that neoplasic glands present more types of anastomosis (40.9%), than healthy glands (33.33%), and an increase in contralateral anastomosis (50%) compared with healthy ones (33%). Given the data, the mammary neoplasia can change the lymphatic drainage pattern in terms of lymph centres and vascular arborization, thus forming new drainage channels and recruiting a larger number of lymph nodes. Lastly, some comments were made about the severity of a specific neoplasic mammary gland and conditions to be considered before making a decision in terms of the most adequate operative procedure, and suggestions for further investigations.

Ocular melanoma and mammary mucinous carcinoma in an African lion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Potential effects of the herbicide Diuron on mammary and urinary bladder two-stage carcinogenesis in a female Swiss mouse model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Extramedullary hematopoiesis in a case of benign mixed mammary tumor in a female dog: cytological and histopathological assessment

Backgroud: Extramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case.Case presentation: Hematopoietic stem cells were found in a benign mixed mammary tumor of a 7-year-old female mongrel dog that presents a nodule in the left inguinal mammary gland. The patient did not have any hematological abnormalities. Cytological evaluation demonstrated two distinct cell populations, composed of either epithelial or mesenchymal cells, sometimes associated with a fibrillar acidophilic matrix, apart from megakaryocytes, osteoclasts, metarubricytes, prorubricytes, rubricytes, rubriblasts, promyelocytes, myeloblasts. Histological examination confirmed the presence of an active hematopoietic bone marrow within the bone tissue of a benign mammary mixed tumor.Conclusions: EMH is a rare condition described in veterinary medicine that can be associated with mammary mixed tumors. It's detection can be associated with several neoplastic and non-neoplastic mammary lesions, i.e. osteosarcomas, mixed tumors and bone metaplasia.

Clinical, histological and immunophenotypic findings in a mare with a mammary lymphoma associated with anaemia and pruritus

An 18-year-old Quarter Horse mare presented with an 18 week history of dermatological lesions characterised by recurrent urticaria and recent signs of enlarged mammary glands, pyrexia, alopecia and intense pruritus. Haematological and serum biochemical analyses revealed anaemia, leucocytosis, thrombocytopenia and hyperfibrinogenaemia. Mammary discharge was evaluated and revealed neutrophilia. Cytological examinations of fine needle aspirates from the parotid lymph nodes were normal. Common causes of anaemia were ruled out by specific tests. The initial diagnosis was mastitis and 2 weeks later the animal returned to the hospital with worsening of clinical signs, intermittent fever, intense pruritus and generalised alopecia. Blood samples were collected for haematological and serum biochemical analyses, and the mammary gland and parotid lymph nodes were biopsied. Rectal palpation revealed a large irregular mass near the left kidney with adhesions of surrounding structures. The animal died before the laboratory results were ready. This report details the clinical, histological and immunophenotypic findings of a case of large lymphoma in a mare.