IMMUNOHISTOCHEMICAL LOCALISATION OF M2 MACROPHAGES IN CANINE MAMMARY TUMOURS USING CD163 MARKER
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Date
2023-03-16
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY
Abstract
The present study entitled “Immunohistochemical localisation of M2 macrophages in canine mammary tumours using CD163 marker” was undertaken to study the expression of a phenotypical marker of M2 macrophages namely CD163 in CMT. It has been reported that presence of the protumourigenic M2 macrophage phenotype was associated with faster and worse progression in human breast cancer. But the studies in veterinary oncology are sparse in this area. Hence, the differential expression of the marker with respect to the grade of the tumour was also evaluated. Excision biopsy samples of mammary tumour suspected growths from presented to University Veterinary Hospitals, Mannuthy and Kokkalai were collected for the study during the time period of December 2020 to October 2021. The highest incidence of CMT was seen in the age group of seven to eight years. All the mammary tumours recorded were in female dogs. Dogs belonging to the breed Labrador (28%) represented the majority of the cases followed by Cross breed (16%) and Dachshund and Rottweiler (12%). Ductal carcinoma, tubulopapillary carcinoma, solid carcinoma, comedocarcinoma, cribriform carcinoma and mixed type of tumours were the histological types observed. Of the
25 samples collected 44% were grade II tumours whereas 28% were grade III and 28% were grade I tumours. Immunohistochemistry was performed to quantify the presence of M2 macrophages by the expression of CD163 marker protein in all cases of canine mammary tumours. Sixteen per cent (4/25) of the tumours were strongly positive (+++) and fifty-six per cent (14/25) were moderately positive (++). The remaining twenty eight percent (7/25) showed weak immunostaining (+) for the protein. Statistical analysis revealed significant positive correlation between the grade of the tumour and CD163 expression (p=0.01). High grade malignant tumours were shown to have strong to moderate CD163 expression, indicating the higher infiltration of M2 macrophages. Lower grades or benign tumours had weak expression of the marker protein indicating lower infiltration. The present study identified the significance of M2 macrophage marker, CD 163 in CMT, with respect to grades of tumours. Further studies with larger number of samples and analysis of its expression in various stages of the disease will help in confirming its role as a prognostic and therapeutic biomarker in CMT.