Chronically infected dogs by the Leishmania infantum parasite may present several systemic manifestations as fever, anemia, progressive weight loss, hepatosplenomegaly, generalized lymphadenopathy and cutaneous lesions. Moreover, some rare dogs can present neurological clinical signs; nevertheless, the pathogenesis of the cerebral form of the visceral leishmaniasis (VL) is still to be elucidated. There are evidences of blood-cerebrospinal fluid barrier breakdown and brain inflammation in dogs with VL, characterized mainly by choroiditis and meningitis. The aim of this study was to evaluate the gene expression of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) in the brain and compare with the choroid plexus in naturally infected dogs by L. infantum. For this purpose, twelve dogs with VL and four uninfected dogs were included in this study. Samples from brain (pool) and choroid plexi were collected in different tubes containing RNAlater®. The RNA was extracted and reverse transcript to cDNA and submitted to RT-qPCR to quantify the gene expression of IL-1β, IL-6 and TNF-α, using specific primers and Taqman® probes. G3PDH was used as a reference gene. There was significative upregulation of IL-1β, IL-6 and TNF-α in the brain of infected dogs, as opposed to the choroid plexus, where there was no difference between the infected and control dogs. This indicates that IL-1β, IL-6 and TNF-α may be produced in the brain and that the choroid plexus is not a site of proinflammatory cytokines synthesis in dogs with VL.

Acknowledgments

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, grant number 2014/01202–9).