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Insulin-like growth factor I is a growth-promoting factor for Leishmania promastigotes and amastigotes.

Authors
  • Goto, H
  • Gomes, C M
  • Corbett, C E
  • Monteiro, H P
  • Gidlund, M
Type
Published Article
Journal
Proceedings of the National Academy of Sciences
Publisher
Proceedings of the National Academy of Sciences
Publication Date
Oct 27, 1998
Volume
95
Issue
22
Pages
13211–13216
Identifiers
PMID: 9789067
Source
Medline
License
Unknown

Abstract

Leishmaniases are diseases caused by protozoa of the genus Leishmania that affect more than 20 million people in the world. The initial phase of the infection is fundamental for either the progression or control of the disease. The Leishmania parasites are injected in the skin as promastigotes and then, after been phagocytized by the host macrophages, rapidly transform into amastigotes. In this phase different nonspecific cellular and humoral elements participate. We have shown previously that insulin-like growth factor (IGF)-I that is constitutively present in the skin induces growth of Leishmania promastigotes. In the present paper we show further evidence for the importance of this factor: (i) IGF-I also can induce a growth response in Leishmania (Leishmania) mexicana amastigotes; (ii) IGF-I binds specifically to a putative single-site receptor on both promastigotes and amastigotes; (iii) IGF-I induces a rapid tyrosine phosphorylation of parasite proteins with different molecular mass in promastigotes and amastigotes of L. (L.) mexicana; and, finally, (iv) the cutaneous lesion in the mice when challenged by IGF-I-preactivated Leishmania (Viannia) panamensis is increased significantly because of inflammatory process and growth of parasites. We thus suggest that IGF-I is another important host factor participating in the Leishmania-host interplay in the early stage during the establishment of the infection and presumably also in the later stages.

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