Insulin-like growth factor (IGF)-I affects parasite growth and host cell migration in experimental cutaneous leishmaniasis.
While the control or progression of leishmaniasis depends on host immune responses, the initial inflammatory process represents a key event. This process involves the participation of several cytokines and growth factors induced during inflammation as well as factors already present at the site of infection such as insulin-like growth factor (IGF)-I. We have previously demonstrated a potential role for IGF-I in experimental cutaneous leishmaniasis based on the significant increase in lesion size seen in mice injected with Leishmania promastigotes preactivated with IGF-I. In the present study we show that preactivation of Leishmania (Leishmania) amazonensis promastigotes with IGF-I induces an increase in the actual number of parasites at the lesion site from seven days postinfection, in addition to a more intense inflammatory infiltrate. There was a higher numerical density of polymorphonuclear neutrophils from 3 to 24 h, and of mononuclear cells from 48 h of infection onward. A higher density of polymorphonuclear neutrophils and mononuclear cells harboring parasites was also observed. The most important observation, however, was that more parasites per cell were present, revealing that IGF-I appears to favour parasite growth within the macrophages. These results strongly suggest an important role for IGF-I in the development of cutaneous leishmaniasis, where it influences both the inflammatory process and parasite growth.
Gomes
C M
CM
Laboratory of Pathology of Infectious Diseases; Department of Preventive Medicine, Instituto de Medicina Tropical de São Paulo, Brazil.
Goto
H
H
Ribeiro Da Matta
V L
VL
Laurenti
M D
MD
Gidlund
M
M
Corbett
C E
CE
D000818:Animals; D006790:Host-Parasite Interactions / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007894:Leishmania mexicana / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology* / Q000473:pathology; D007958:Leukocyte Count; D051379:Mice; D008807:Mice, Inbred BALB C; D009504:Neutrophils / Q000469:parasitology; D011994:Recombinant Proteins / Q000494:pharmacology
D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I