Receptores da imunidade inata na Leishmaniose visceral canina

Abstract

Dogs are the primary reservoirs of parasites of the Leishmania genus. Innate immune receptors perform early detection of the parasite and lead to specific adaptive immune response in attempt to infection control. However, few studies have investigated a correlation between the expression of innate immunity receptors and the resistance or susceptibility pattern in dogs naturally infected with Leishmania infantum. The aim of this study was to correlate the clinical status of dogs naturally infected with L. infantum with the mRNA expression levels of innate imune receptors (Toll like receptors-TLRs and Nod Like Receptors-NLRs). Initially, serum of 76 dogs was collected at the Zoonoses Control Center in Natal, Rio Grande do Norte, Brazil. The L. infantum infection in dogs was confirmed by ELISA and DPP® tests. Subsequently, animals were clinially evaluated and classified as asymptomatic (n=19), oligosymptomatic (n=19), symptomatic (n=19) and uninfected (n=19). Dogs naturally infected by L. infantum and uninfected controls were euthanasied and liver samples were collected to quantify mRNA expression of TLRs (TLR1-9), Nod Like receptors-NLRs (NOD1, NOD2, NLRP1, NLRP3), cytokines (IL1β, IL-6, IL-12, IL-10, TNFα, IFN-γ) and iNOS using real-time PCR. The results demonstrate the increased expression of almost all TLRs and NLRs in dogs naturally infected by L. infantum compared with uninfected animals. However, symptomatic dogs showed higher expression of TLR1, TLR2, TLR3, TLR4, TLR5, TLR7, TLR8 NLRP1, NLRP3, NOD1 and IL-1β than asymptomatic animals, revealing significant up regulation of transcription with disease progression. On the other hand, asymptomatic dogs presented greater cytokine mRNA expression (IFN-γ, IL-12) and iNOS when compared to oligosymptomatic and asymptomatic animals. This study unveil new knowledge involving innate immunity receptors (TLRs, NLRs) and cytokines in canine visceral leishmaniasis and may be used as a basis for better understanding of resistance or susceptibility mechanisms in dogs infected with L. infantum, as well as prophylactic strategies to control canine visceral leishmaniasis.