Nitric Oxide, Protein Oxidation and Total Antioxidant Levels in Serum of Dogs Naturally Infected by Ehrlichia canis, Leishmania infantum and Babesia vogeli

Background: Ehrlichia canis and Babesia vogeli comprise a group of globally distributed pathogens transmitted by ticks. Leishmania infantum is transmitted by Lutzomyia longipalpis, etiological agent of leishmaniasis. The pathogens affect the animals; and can also affect the human. An imbalance between oxidants and antioxidants compounds causes an increase in free radicals, and other reactive oxygen species (ROS) has play an important role in tissue damage in a variety of pathological processes, as parasitic disease. The objective of this study was to evaluate the nitric oxide levels, protein oxidation and total antioxidant status in serum of dogs infected by L. infantum, E. canis and B. vogeli. Materials, Methods & Results: Blood samples from dogs originating from the city of Campo Grande, Mato Grosso do Sul state, Brazil were collected to research hemoparasites by polymerase chain reaction (PCR) using specific primers for each parasite. Serum samples obtained from 54 dogs with single and co-infection were used this study: L. infantum (n = 19), E. canis (n = 8), B. vogeli (n = 5), L. infantum and E. canis (n = 12), L. infantum and B. vogeli (n = 4), and E. canis and B. vogeli (n = 6), as well as 17 normal controls (uninfected). Samples were stored at -80oC for further evaluation of NO x , AOPP, and FRAP levels using Cobas Mira automated analyzer, and results were expressed as μmol/L. NO x , AOPP and FRAP levels were increased (P < 0.01) in dogs infected by parasites when compared to uninfected animals. Levels of NO· and AOPP in dogs naturally infected by Babesia vogeli and Ehrlichia canis, respectively, did not differ from the control group (uninfected). The higher NO x levels were observed in the serum of dogs with co-infection by L. infantum and E. canis, and L. infantum and B. vogeli (P < 0.01). Altogether, our results indicate that dogs naturally infected by L. infantum, E. canis and B. vogeli developed a state of redox imbalance. Discussion: Oxidative stress in dogs infected by L. infantum, Ehrlichia canis, and B. vogeli, single or coinfected were verified this study. As a result, naturally infected dogs sampled in the present study showed augmented levels of ROS, as well as in serum samples of dogs infected by Babesia gibsoni, Leishmania spp., Hepatozoon canis, and Trypanosoma evansi. Nitric oxide increased (detected by high NO x levels) can be a marker of oxidative stress, as well as an important mediator of inflammatory response. In experimental conditions, an increased level of NO x in dogs infected with E. canis was observed, and researchers say this increase was directly related to the pathogenesis of the disease. The imbalance of oxidants and antioxidants is present in various animal species in many pathological situations including parasitic diseases, as in dogs infected by hemoparasites showed increased oxidative markers (NO· and AOPP) associated with increased antioxidant levels (FRAP), which features a status of oxidative stress. The increase of FRAP is interpreted as the elevation of total antioxidant levels, i.e. enzymatic and non-enzymatic. The increased antioxidant is good to the host, it has the function of neutralizing the oxidizing or reducing that when high levels are toxic to cells and tissues. Therefore, we suggest that the infections caused by these hemoparasites cause oxidative stress and this process may participate in disease pathology.