Aspectos histopatológicos do baço na infecção por Leishmania infantum em camundongos BALB/C tratados com CXCL10

Abstract

Visceral leishmaniasis is an infectious parasitic vectoral disease caused by the obligate intracellular protozoa from the genus Leishmania sp., being Leishmania infantum (syn. chagasi) prevalent in Brazil. It s a fatal anthropozoonosis , which kills 95% of the untreated people in 2 years after diagnosis. Canids, felids and marsupials are also hosts of Leishmania sp. When present, the main symptoms are irregular fever, pallor, anaemia, pancytopenia, hepatosplenomegaly, anorexia and cachexia. The involvement of the liver and the spleen is the main immunosuppressing effect on the host, exposing it to coinfections. The in fectious course in the spleen still presents many aspects to be uncover ed, mainly in what concerns its impaired microarchtecture against the parasite's persistence. The treatment with the chemokine CXCL10 is investigated because of it s potencial protectin g effect against leishmaniasis. The goal of this analysis was to evaluate the relation between the L. infantum infection with the microarchtecture of the spleen in BALB/c mice treated with CXCL10 and to correlate with a possible protective action of CXCL10 . Groups of BALB/c mice (n=36) infected with L. infantum were treated (n=18) or not (n=18) with CXCL10 (5 μ g/kg, via i.p.) on days 1, 3, and 7 after infection and 10, 30 and 45 days after infection. Hematoxylin Eosin staining and impregnation by AgNO 3 (ret iculin) o n histological spleen slides were performed to assess: (i) lymphoid proliferation of white pulp, (ii) quantity and quality of white pulp structures, (iii) condition of the splenic microarchitecture according to Santana et al. 2008 and (iv) cellula rity of the red pulp. The analysis comprised descriptive and inferential statistics using open statistical R® software and open imagej® software. The results showed that the treatment kept the organization of the white pulp of the spleen 30 days after infe ction and kept the germinal centers of lymphoid follicles 10 and 45 days after infection, indicating the prevention of a bigger rupture of the splenic microarchitecture with relative reaction of the organ against the pathogen. There was no reduction of th e loss of the red pulp cellularity and no effect of the chemokine on the lymphoid proliferation of the white pulp. In short, CXCL10 is a chemokine with great potential for the treatment of leishmaniasis and this work opens an avenue to new studies with thi s or other chemokines presenting immunolodulating effects.