TLRs expression in canine mammary gland neoplasms: a pathological and molecular study

TLRs are a class of PRRs that play a vital role in innate immunity. TLRs are expressed on immune cells and mammary epithelial cells. They can promote tumor growth, angiogenesis, invasion, and viability signaling. The current study aimed to test the correlation between histologic types and grades of neoplasms and TLRs gene expression levels. Twenty-one tissue samples of canine mammary neoplasms were stained with H&E. Then, it evaluated histologic type and grade according to the methods of Goldschmidt et al. and Peña, respectively. We established real-time PCR quantification assays to measure the mRNA abundances of TLRs in normal and neoplastic mammary glands. Profile pattern of TLR 1, 2, 3, 4, 5, 6, and 9 genes expression in canine mammary glands performed in 21 samples of mammary gland neoplasms and three non-neoplastic mammary gland samples from normal dogs. TLR 3, 4, and 9 mRNA overexpression were detected. In addition, tubulopapillary carcinoma grade II, SCC grade III, and carcinoma mixed type grade II demonstrated the highest relative TLR-3, and 9 mRNA expression levels. Complex carcinoma grade I, ductal carcinoma grade II, and anaplastic carcinoma grade II showed the highest relative TLR4 mRNA expression level. Although histopathological characteristics of tumors, including histologic type, grade, and inflammation, influenced TLRs mRNA expression level, such correlation was insignificant (P > 0.05). •Mammary gland neoplasms are a common animal health issue.•qRT-PCR is a useful method for TLRs mRNA relative gene expression level assessment.•TLRs mRNA expression level in malignant mammary neoplasms was higher than benign mammary neoplasms.•TLRs expression level in neoplasms with inflammatory reaction was higher than neoplasms without inflammatory reaction.