Cardiomyocyte marker expression in dogs with left atrial enlargement due to dilated cardiomyopathy or myxomatous mitral valve disease

Introduction. Dilated cardiomyopathy (DCM) and myxomatous mitral valve disease (MMVD) are common heart conditions in dogs. They have different etiology and pathogenesis and although other studies focused on changes in the left ventricles of the affected hearts, the aim of our study was to assess the expressions of some intrinsic proteins in the enlarged left atria. Material and methods. We performed an immunohistochemical analysis of left atrial specimens obtained from 15 dogs with DCM, 35 dogs with MMVD and six control dogs. We assessed the expression of following proteins: SERCA1, SERCA2, sarcomeric actinin, smooth muscle actin, and dystrophin. Results. We noted a higher percentage of SERCA1-positive cells in the MMVD group and lower percentage of dystrophin-positive cells in the DCM group as compared to control group. The expression of other proteins was similar in the hearts of control dogs and dogs with heart diseases. Conclusions. The observed changes in the expression patterns of some proteins in the atria of dogs with DCM and MMVD suggest that atrial enlargement relies not only on volume overload, but also alterations of the intrinsic proteins can contribute to the pathogenesis of dilated cardiomyopathy.

TRPV1 Receptor Identification in Bovine and Canine Mitral Valvular Interstitial Cells

Myxomatous mitral valve degeneration (MMVD) is the most common acquired cardiac disease in canine species, and valvular interstitial cells (VICs) are considered the main responsible for the development of this pathology. The scientific interest is focused on isolating and characterizing these cells. The aims of the present study were to verify a novel VICs mechanical isolation method and to characterize isolated cells using immunocytochemistry and immunofluorescence, with parallel histological and immunohistochemistry assays on bovine and canine healthy and MMVD mitral valves. Antibodies against vimentin (VIM), smooth muscle actin (SMA), von Willebrand (vW) factor, Transforming Growth Factor (TGF) β1, and Transient Receptor Potential Vanilloid 1 (TRPV1) were used. The isolation method was considered reliable and able to isolate only VICs. The different assays demonstrated a different expression of SMA in healthy and MMVD mitral valves, and TRPV1 was isolated for the first time from bovine and canine VICs and the correspondent mitral valve leaflets. The novelties of the present study are the new isolation method, that may allow correlations between laboratory and clinical conditions, and the identification of TRPV1, which will lead to further investigations to understand its function and possible role in the etiology of MMVD and to the design of new therapeutic strategies

Inhibin-α, E-cadherin, calretinin and Ki-67 antigen in the immunohistochemical evaluation of canine and human testicular neoplasms

Introduction. The steady increase of dogs with diagnosed testicular neoplasms observed in recent years prompted us to carry out immunohistochemical (IHC) studies for their better characterization. The aim of the study was to analyze most common canine testicular neoplasms (seminomas, Leydig cell and Sertoli cell tumors) with selected IHC markers and to compare the expressions of these proteins in corresponding canine and human testicular tumors. Material and methods. Studies were carried out on testicular canine tumors: 40 cases of seminoma, 40 cases of Leydig cell tumor and 40 cases of Sertoli cell tumor. Moreover, 15 cases of human seminomas and 5 cases of human Leydig cell tumors were also analyzed. Immunohistochemistry was performed on paraffin sections by standard technique using monoclonal anti-human antibodies against E-cadherin, inhibin-α, calretinin and Ki-67. The slides were subjected to computer-aided image analysis and the intensity of the immunoreactivity was assessed by a semi-quantitative scoring system. Results. Due to the very low prevalence of the Sertoli cell-derived tumors in the human population, we were able to examine the markers’ expression only in the canine gonadal tumors. We revealed that, apart from E-cadherin in Leydig cell tumors and calretinin in seminomas, the expression of all the analyzed markers in canine and human testicular tumors was similar. E.g. there was no immunoexpression of inhibin-α in 75% of canine and 100% of human cases of seminoma. The immunoreactivity of Ki-67 was intense in 40% of canine and 60% of human seminomas. Immunoexpression of inhibin-α in Leydig cell tumor was intense in 70% of canine and 100% of human cases, respectively. Also the immunoreactivity of calretinin was intense in 75% of cases of canine and 100% of human Leydig cell tumors. In 50% of canine and 40% of human Leydig cell tumors, the immunoexpression of Ki-67 was weak. Conclusions. The applied anti-human monoclonal antibodies against common antigens and markers of human testicular neoplasms could be routinely used for the immunohistochemical evaluation of canine testicular tumors.

Epidemiological and pathological features of primary cardiac tumours in dogs from Poland in 1970–2014

Primary heart tumours affect less than 1% of dogs. Due to their rare incidence, every research showing the frequency of cardiac tumours is valuable. Routine diagnostics is often complemented with immunohistochemical analysis. This study was conducted on 110 patient records from all veterinary faculties in Poland from dogs diagnosed with heart tumours between 1970 and 2014. The dogs’ age, breed and sex with tumour localisation and histopathological diagnosis were analysed. Because of its most common incidence, samples of haemangiosarcoma underwent further examination with assessment of the expression of cell markers that have not been evaluated earlier (i.e. minichromosome maintenance proteins and beta-catenin). We noted 111 tumours including 88.3% malignant and 10.8% benign ones. Haemangiosarcoma and aortic body tumour were the most frequent cardiac neoplasms in the dogs examined (45.9% and 27.9% of all tumours, respectively). Immunohistochemical analysis of haemangiosarcoma showed a positive expression of all markers examined. CD31, vimentin, and beta-catenin showed a positive reaction in all 11 samples examined. At least one proliferative marker (Ki-67, MCM-3 or MCM-7) showed a positive reaction in each sample. MCM-3 showed a higher expression than the two other proliferative markers (P = 0.006), but only Ki-67 showed a positive correlation with the mitotic index (P > 0.05, r = 0.89). Although beta-catenin, MCM-3 and MCM-7 showed a positive reaction in the haemangiosarcomas examined, their usefulness as diagnostic and prognostic factors should be a topic of further research

Useful immunohistochemical indicators in canine mast cell tumours

Morphological and immunohistochemical analysis of 45 canine mast cell tumours was performed to determine whether the proteins examined are useful for a more precise description of tumour morphology and a more reliable determination of the prognosis in patients. Tissue sections were stained according to the standard haematoxylin and eosin (HE) technique and with toluidine blue to demonstrate cytoplasmic granules. Immunohistochemical studies were performed, using the cell markers CD117 (c-kit), p16 and von Willebrand factor (FVIII). In CD117 three different staining patterns were observed: (1) membranous reaction, (2) intense staining of cytoplasm, and (3) a diffuse, delicate cytoplasmic reaction. Von Willebrand antibody was evaluated on the basis of the number of blood vessels stained. p16 expression was evaluated by scoring positive nuclear reaction. Positive expression was demonstrated for all examined antigens, but their level of expression differed depending on the grades of tumour malignancy. Statistical analysis of the results documented a pronounced positive correlation between the markers studied and the grade of tumour malignancy (P < 0.001). It was shown that each of the cell markers examined represents a useful prognostic indicator for patients with mast cell tumours. The calculated correlation coefficients demonstrate a strong association between the expressions of CD117, FVIII and p16, and the histological malignancy of a tumour