Keratin and vimentin distribution patterns in the epithelial structures of the canine anal region

Derivation of adult canine intestinal organoids for translational research in gastroenterology

Background

Large animal models, such as the dog, are increasingly being used for studying diseases including gastrointestinal (GI) disorders. Dogs share similar environmental, genomic, anatomical, and intestinal physiologic features with humans. To bridge the gap between commonly used animal models, such as rodents, and humans, and expand the translational potential of the dog model, we developed a three-dimensional (3D) canine GI organoid (enteroid and colonoid) system. Organoids have recently gained interest in translational research as this model system better recapitulates the physiological and molecular features of the tissue environment in comparison with two-dimensional cultures.

Results

Organoids were derived from tissue of more than 40 healthy dogs and dogs with GI conditions, including inflammatory bowel disease (IBD) and intestinal carcinomas. Adult intestinal stem cells (ISC) were isolated from whole jejunal tissue as well as endoscopically obtained duodenal, ileal, and colonic biopsy samples using an optimized culture protocol. Intestinal organoids were comprehensively characterized using histology, immunohistochemistry, RNA in situ hybridization, and transmission electron microscopy, to determine the extent to which they recapitulated the in vivo tissue characteristics. Physiological relevance of the enteroid system was defined using functional assays such as optical metabolic imaging (OMI), the cystic fibrosis transmembrane conductance regulator (CFTR) function assay, and Exosome-Like Vesicles (EV) uptake assay, as a basis for wider applications of this technology in basic, preclinical and translational GI research. We have furthermore created a collection of cryopreserved organoids to facilitate future research.

Conclusions

We establish the canine GI organoid systems as a model to study naturally occurring intestinal diseases in dogs and humans, and that can be used for toxicology studies, for analysis of host-pathogen interactions, and for other translational applications.

Electronic supplementary material

The online version of this article (10.1186/s12915-019-0652-6) contains supplementary material, which is available to authorized users.

Quantification of morphology of canine circumanal gland tumors: a fractal based study

Circumanal gland tumors are very common neoplasms of dogs. Their classification relies on microscopic examination and is further supported by a few immunohistochemical markers that help indicate their prognosis. However, new additional tests would be highly useful. The purpose of this study was to develop such a test using fractal analysis which is increasingly being applied in science, especially in the field of biomedicine. A total of 53 circumanal gland tumors were chosen from our department archives. After a precise histological classification according to the World Health Organization classification, the number of de novo classified samples was as follows: 15 adenomas, 11 epitheliomas, 21 well differentiated carcinomas, 6 poorly differentiated carcinomas. Ten samples of normal circumanal gland were also included as control. All samples were immunohistochemicaly stained with vimentin. All immunohistochemical reactions were photographed at two different magnifications -100X and 400X- and converted to 1 bit in black and white (bitmap) images, thus enhancing the positive vimentin reactions. These images were used for the assessment of fractal dimension applying the box counting method and computer software Fractalyse. To determine the significance of results, conventional statistics were performed using Statistica software.

The overall vimentin stain score was significantly higher in epitheliomas and carcinomas than in normal circumanal glands (CG) or adenomas. Mean values of fractal dimension estimated at magnification 100X and 400X were as follows: normal CG 1.318 and 1.372, CG adenomas 1.384 and 1.408, CG epitheliomas 1.547 and 1.597, CG well differentiated carcinomas 1.569 and 1.607, CG poorly differentiated carcinomas 1.679 and 1.723. Significant differences (at level of 5%) of these values were observed between individual groups of CG adenomas or normal CG, and epitheliomas or carcinomas.

The above results indicate vimentin immunohistochemistry staining and assessment of fractal dimension as an ancillary diagnostic method of choice when discerning between benign and malignant tumors of circumanal glands. Additional development of the method of fractal dimension assessment may yield a possibility for this tool to successfully discern between all of the types of CG tumors.

Primary penile adenocarcinoma with concurrent hypercalcaemia of malignancy in a dog

A 13-year-old male neutered Siberian husky crossbreed dog was presented with a 3-week history of haematuria and penile swelling. Clinical examination and computed tomography demonstrated a soft-tissue mass located at the base of the penis without signs of other primary tumours or metastasis. Clinicopathological findings revealed paraneoplastic hypercalcaemia. Fine-needle aspiration cytology of the mass suggested an epithelial tumour with several criteria of malignancy present. Following surgical excision of the mass, the hypercalcaemia resolved. Histopathology and immunohistochemistry revealed features consistent with an adenocarcinoma. Despite thorough examination, no perineal or anal sac tumour was found. To the authors' knowledge, this is the first reported case of a penile adenocarcinoma with hypercalcaemia of malignancy.

Primary Clitoral Adenocarcinoma With Secondary Hypercalcemia of Malignancy in a Dog

This report describes a primary clitoral adenocarcinoma in a dog with secondary hypercalcemia of malignancy. A 10-year-old, spayed female basset hound was evaluated for a mass protruding from the vulva. The mass was excised, and a histological diagnosis of clitoral adenocarcinoma was made. No evidence of metastasis on thoracic radiographs or abdominal ultrasound was seen. Preoperative hypercalcemia resolved following excision of the mass. Cellular features were similar to an apocrine gland anal sac adenocarcinoma, and immunohistochemistry exhibited features noted with apocrine gland anal sac adenocarcinoma. No further treatment was elected by the owner. Internal iliac lymph-node metastasis was identified 4 weeks postoperatively, and hypercalcemia recurred 8 weeks postoperatively. The dog was euthanized 22 weeks postoperatively for signs related to hypercalcemia, including polyuria/polydipsia, lethargy, and weakness. A necropsy was performed and confirmed the presence of internal iliac lymph-node metastasis. The colon, rectum, and anal sacs were grossly and histologically normal. To our knowledge, this is the first reported case of clitoral neoplasia in the dog.

Cellular terrain surrounding sympathetic nerve pathways in the rat orbit: comparisons of orbital connective tissue and smooth muscle cell phenotypes

Sympathetic axons are abundant within some orbital tissues but are absent from others. This study investigated cellular phenotypes of tissues containing sympathetic nerves en passage and compared these with phenotypes in regions devoid of sympathetic nerves and with smooth muscle targets. Two primary orbital smooth muscle targets, the tarsal muscle and orbital muscle, contained many synaptophysin-immunoreactive nerves. Target cells had ultrastructural features typical of smooth muscle and were immunoreactive for alpha-smooth muscle actin, smooth muscle myosin heavy chain, desmin, vinculin, and laminin, but not non-muscle myosin, vimentin, fibronectin, or type IV collagen; nerve growth factor (NGF) mRNA was detected by reverse transcription-polymerase chain reaction. Periorbital sheath devoid of sympathetic nerves contained elongated fibroblasts that were immunoreactive for vimentin, non-muscle myosin, and fibronectin, but not for alpha-smooth muscle actin, smooth muscle myosin heavy chain, vinculin, desmin, laminin, or type IV collagen, and did not express NGF mRNA. Regions of periorbital sheath containing sympathetic nerves had few synaptophysin-immunoreactive varicosities. Cells in this region contained myofilaments, ribosomes, and rough endoplasmic reticulum and were larger than tarsal muscle cells. They expressed NGF mRNA and showed a unique immunophenotype, reacting for vimentin, alpha-smooth muscle actin and myosin heavy chain, desmin, vinculin, laminin, and type IV collagen. This phenotype reflects both fibroblast and smooth muscle features similar to myofibroblasts or transdifferentiated smooth muscle described in other tissues. The spatial association between these cells and sympathetic nerves suggests that they may be involved in axon guidance or maintenance.

Circumanal glands of the dog: a new classification and cell degeneration

BACKGROUND

The circumanal glands of the dog are thought to be a glandular tissue, but there is some controversy as to whether they should be classified as exocrine or endocrine. In this study, we examined the nature of the circumanal glands to determine whether they should be described as exocrine, endocrine, or something else altogether. In addition, we investigated the cell degeneration in lobules of the circumanal glands in relation to the apocrine glands.

METHODS

Light microscopic observations were made of paraffin sections stained with hematoxylin and eosin, and after immunohistochemical staining with antibodies against alpha-smooth muscle actin, keratin, filaggrin, and 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD). Samples were also examined by electron microscopy after fixation by aldehyde perfusion.

RESULTS

The lobules of circumanal glands could be divided into two types on the basis of the presence or absence of cysts. Four layers (I-IV) were detected in the lobules with cysts. The outermost layer (layer I or the basal layer) consisted of flattened cells that contained bundles of tonofilaments and were stained immunohistochemically with the antibody against keratin. Layer II (the polyhedral or "spinous" layer) consisted of polyhedral cells that contained bundles of tonofilaments. These cells were connected to adjacent cells by desmosomes, interdigitations, and gap junctions, and they were immunopositive for keratin. A small number of polyhedral cells were immunopositive for 3beta-HSD. Layer III (the granular layer) was composed of flattened cells that contained hematoxylin-stainable granules and were moderately immunopositive for filaggrin. The innermost layer (layer IV or the horny layer) consisted of keratin. Lobules without cysts consisted only of layer I (the basal layer) and layer II (the polyhedral layer). Lobules of the circumanal glands were not directly connected to apocrine glands. Polyhedral cells degenerated and were phagocytosed by basal cells at a periphery of lobules. Then, basal cells phagocytosing degenerated polyhedral cells escaped from lobules, moved into the walls of apocrine glands, and, finally, dropped into the lumen of apocrine glands.

CONCLUSIONS

Lobules of the circumanal glands have many characteristics of epidermis (a basal layer, a polyhedral or "spinous layer," a granular layer, and a horny layer) and they should not be classified as glandular tissue. The cysts in lobules can be interpreted as "closed hair canals." We suggest that steroid metabolism might occur in the polyhedral cells of the lobules.