Immune-mediated gene expression of il-6 and TGF-β1 during progression and regression of canine transmissible venereal tumour

Abstract

Canine transmissible venereal tumor (CTVT) is a unique, naturally and experimentally transmitted contagious venereal tumor of dogs which is commonly present in stray dogs exhibiting unrestrained sexual activity. The mutated and contagious tumor cell is the causative agent. This study was conducted to evaluate the genetic expression of TGF-β1 and IL-6 cytokines, T-cell response towards Concanavalin A and hematological and biochemical changes during the progression and regression of the CTVT. The signalment and clinical history of 12 client-owned TVT affected dogs were recorded. Tissue samples were obtained through biopsy, and blood samples were collected for diagnostic confirmation using reverse transcriptase PCR. The RT-PCR products from CTVT samples were further purified and sequenced. Regression of the tumor was performed using intravenous injections of vincristine sulphate at weekly intervals. Significant genetic expression of TGF-β1 was observed in the progressive phase of CTVT, whereas genetic expression of IL-6 was significant in the regressive phase of CTVT after chemotherapy. Cell-mediated immunity also plays an important role in the regression of canine transmissible venereal tumors. Notably, a significant (P<0.05) increase in the mean stimulation index of the lymphocyte stimulation test and hemoglobin level, non-significant (P>0.05) changes in the number of neutrophils, lymphocytes, monocytes and eosinophils, and slight hypoproteinemia and hypoalbuminemia were observed after chemotherapy with vincristine sulphate in CTVT affected animals. Overall, our results delineate the critical roles of T cells, TGF-β1 and IL-6 in triggering the progression and regression of CTVT, which can be promising in developing potential immunotherapy against CTVT.