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The canine transmissible venereal tumour (CTVT) is a transmissible cancer that is spread naturally between dogs, with the ability to develop and evade the immune system, despite strict immune surveillance of the host. Furthermore, molecular signalling between cells of the immune system and the tumour microenvironment appear to influence the behaviour and development of the tumour. Thus, this study aimed to quantify the expression of genes related to the immune system such as IL-6, IFN-γ, and TGF-β, as well as angiogenic factors (VEGF, CXCR4), in CTVT cells in vivo and in vitro (primary culture), correlating with the clinical response of the animals treated with vincristine. As expected, the most prevalent subtype was plasmacytoid cells, although lymphocytic cells were also found, indicating the possibility of polyclonality. When we compared the gene expressions of IFN-γ and IL-6, we mostly found low expression, concluding that MHC expression was probably not occurring in tumour cells, and no activation of immune cells to eliminate the tumour. The TGF-β gene was normal in the majority of animals but demonstrated decreased expression in vincristine resistant animals, leading to the hypothesis that the concentration of tumour-derived TGF-β was affecting and even suppressing the real TGF-β expression, favouring tumour proliferation and progression in these cases. VEGF expression was extremely high, demonstrating its angiogenic role in tumour growth, while CXCR4 was decreased, possibly because of CTVT's low metastatic potential. Thus, we concluded that the tumour microenvironment, together with the immune system of the host, influences CTVT, presumably altering its tumorigenesis and the animal's clinical response to treatment., (© 2018 John Wiley & Sons Ltd.)

Transmissible venereal tumour (TVT) generally presents different degrees of aggressiveness, which makes them unresponsive to conventional treatment protocols. This implies a progressive alteration of their biological profile. This study aimed to evaluate the cytotoxicity, cell survival, apoptosis and cell cycle alterations in TVT cell cultures subjected to treatment with vincristine. Similarly, it assessed possible implications of MDR-1, TP53, BCL-2, and BAX gene expressions in eight TVT primary cultures for both resistance to chemotherapy and biological behaviour. When comparing TVT cells receiving vincristine to those untreated, a statistical difference related to increased cytotoxicity and decreased survival rates, and alterations in G1 and S cell cycle phases were found but without detectable differences in apoptosis. Increased MDR-1 gene expression was observed after treatment. The groups did not differ statistically in relation to the TP53, BAX and BCL-2 genes. Although preliminary, the findings suggest that such augmented expression is related to tumour malignancy and chemotherapy resistance., (© 2016 John Wiley & Sons Ltd.)

The aims of this study were to investigate the presence of Leishmania infantum and possible co-infection with Anaplasma platys , Babesia vogeli, Ehrlichia canis , and Toxoplasma gondii in the brain of 24 dogs naturally infected by L. infantum . A total of 24 mongrel adult dogs (22 clinically affected, 2 with neurological signs, and 2 subclinically infected) aged between 2 and 5 yr, naturally infected by visceral leishmaniasis, were selected. Fragments from meninges, frontal cortex, thalamus, cerebellum, and choroid plexus of the lateral ventricles and fourth ventricle were collected, mixed, and tested by real-time polymerase chain reaction (qPCR). Leishmania infantum DNA was detected in 95.8% (23/24) of the infected dogs, including the subclinically infected. A total of 14/24 (58.3%) dogs were co-infected by E. canis and L. infantum , 4/24 (16.7%) were co-infected by E. canis , B. vogeli, and L. infantum , 2/24 (8.3%) were co-infected by B. vogeli and L. infantum , and 1/24 (4.2%) dog was co-infected by E. canis , B. vogeli, T. gondii , and L. infantum . All 24 brain samples tested negative for A. platys . These results demonstrate that L. infantum is able to penetrate into the brain parenchyma, either alone or in association to other zoonotic pathogens. In addition, qPCR could be considered for adequate evaluation of Leishmania in the brain tissue of dogs with neurological signs that have died.