Enhancement of experimental cutaneous leishmaniasis by Leishmania extract: identification of a disease-associated antibody specificity.

Virgínia M G Silva,Pablo R S Oliveira,Isabela C Navarro,Lain Pontes–De-Carvalho,Cíntia F De-Araújo

doi:10.1186/s13104-015-1158-0

Abstract

BackgroundBoth Leishmania braziliensis and Leishmania amazonensis induce cutaneous disease when injected in the skin of BALB/c mice. However, L. amazonensis may also visceralize in that strain of mice, infecting mainly the liver and spleen. In addition, whereas BALB/c mice die with a progressive cutaneous disease when infected by L. amazonensis, the infection by L. braziliensis is spontaneously cured. In a previous work, we have found that intravenous injections of L. amazonensis amastigote extract (LaE) potentiated a L. braziliensis infection in BALB/c mice, and that this infection-promoting activity could be inhibited by the addition of protease inhibitors to the extract.MethodsIn order to detect markers of disease evolution, in the present work we analyzed the specificity of the anti-L. amazonensis antibody response of L. braziliensis-infected BALB/c mice injected intravenously with saline or LaE, supplemented or not with protease inhibitors, by the Western blot technique.ResultsIgG1 antibodies recognizing an antigen with apparent molecular weight of 116 kDa were specifically detected in BALB/c mice that had been turned susceptible to L. braziliensis infection by injections of LaE.ConclusionA Th2 immune response (IgG1 antibody-producing) against this 116 kDa antigen, therefore, could be associated with susceptibility to severe Leishmania infection.

Highlights

Both Leishmania braziliensis and Leishmania amazonensis induce cutaneous disease when injected in the skin of BALB/c mice
Lesion size and parasite burden in experimentally infected mice In a previously published work, we have shown that injection of L. amazonensis amastigote extract (LaE) together with protease inhibitors abolished the enhancing effect of the LaE on the Leishmania infection in BALB/c mice [22]
As in previously published work, the four biweekly intravenous injections of LaE significantly increased the size of the lesions caused by L. braziliensis in BALB/c mice (Fig. 1a), whereas the group of mice that received LaE in the presence of protease inhibitors did not differ significantly from the control group

Summary

Introduction

Both Leishmania braziliensis and Leishmania amazonensis induce cutaneous disease when injected in the skin of BALB/c mice. Whereas BALB/c mice die with a progressive cutaneous disease when infected by L. amazonensis, the infection by L. braziliensis is spontaneously cured. We have found that intravenous injections of L. amazonensis amastigote extract (LaE) potentiated a L. braziliensis infection in BALB/c mice, and that this infection-promoting activity could be inhibited by the addition of protease inhibitors to the extract. Depending on the Leishmania species or isolate, and on the nature of the host immune response, the infection can cause distinct forms of disease, ranging from self-limiting cutaneous lesions to lethal visceral illness [1,2,3]. Different species of Leishmania cause distinct diseases in mice. The genetic background of the mouse affects the outcome of the infection [14,15,16,17]

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Discussion

Conclusion