Naturally Leishmania infantum-infected dogs display an overall impairment of chemokine and chemokine receptor expression during visceral leishmaniasis.

Dogs are the primary reservoir for Leishmania parasites. The immune response induced by Leishmania infantum infection in these animals has not been completely elucidated, and few studies have investigated the relationship between the expression levels of chemokines and chemokine receptors and the clinical status of dogs with canine visceral leishmaniasis (CVL). The aim of this study was to correlate the clinical status of naturally L. infantum-infected dogs (from rural areas of Mossoró city, State of Rio Grande do Norte, Brazil) with the expression levels of chemokines (ccl1, ccl2, ccl3, ccl4, ccl5, ccl17, ccl20, ccl24, ccl26, cxcl9, cxcl10) and chemokine receptors (cxcr3, ccr3, ccr4, ccr5, ccr6, ccr8) in the liver and spleen determined using real-time PCR. Twenty-one dogs were clinically evaluated and classified as asymptomatic (n=11) or symptomatic (n=10). Splenomegaly, weight loss and onychogryphosis were the most pronounced symptoms. In the liver, the mRNA expression levels of ccl1, ccl17, ccl26, ccr3, ccr4, ccr5, ccr6, and ccr8 were lower in symptomatic animals than in asymptomatic animals. Compared with uninfected animals, symptomatic dogs had lower expression levels of almost all molecules analyzed. Moreover, high clinical scores were negatively correlated with ccr5 and ccr6 expression and positively correlated with cxcl10 expression. We conclude that the impairment of the expression of chemokines and chemokine receptors results in deficient leukocyte migration and hampers the immune response, leading to the development of disease.

Trypanosoma cruzi: biodistribution of technetium-99m pertechnetate in infected rats.

With the aim of investigating the biodistribution of technetium-99m pertechnetate ((99m)TcO4-) in rats infected with Y strain of Tripanosoma Cruzi, at the peak of parasitemia, (14th day of infection), we injected Wistar rats with 0.1 ml of (99m)TcO4- (3.7MBq). After 60 min, the percentage of radioactivity per gram was counted in several isolated organs and blood, using a gamma counter (1470 Wizard, PerkinElmer Finland). The uptake of (99m)TcO4- increased significantly in blood and decreased in the colon of infected animals (p<0.05). A significant reduction in serum iron and red blood cells and a significant increase in total proteins, leukocytes and lymphocytes in the infected rats were observed, compared with controls (p<0.05). A reduction in muscle layer thickness of the colon and mononuclear inflammation were observed. These results conclusively demonstrate that T. cruzi infection would be associated with changes in the biodistribution of (99m)TcO4- and in colon morphology, with potential clinical implications.