Insulin-Like Growth Factor I is a Growth-Promoting Factor for Leishmania Promastigotes and Amastigotes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 95; no. 22; pp. 13211 - 13216
• Main Authors: Goto, H., Gomes, C. M. C., Corbett, C. E. P., Monteiro, H. P., Gidlund, M.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 27-10-1998; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Amastigotes; Animals; Biological Sciences; Disease; Female; Humans; Infections; insulin-like growth factor I; Insulin-Like Growth Factor I - pharmacology; Insulin-Like Growth Factor I - physiology; Insulin-Like Growth Factor II - pharmacology; Leishmania; Leishmania - drug effects; Leishmania - growth & development; Leishmania mexicana - drug effects; Leishmania mexicana - growth & development; Leishmaniasis, Cutaneous - parasitology; Leishmaniasis, Cutaneous - physiopathology; Lesions; Macrophages - parasitology; Male; Medical research; Mice; Mice, Inbred BALB C; Parasite hosts; Parasites; Parasitism; Phagocytosis; Phosphorylation; Promastigotes; Receptors; Recombinant Proteins - pharmacology; Skin - parasitology; Skin - physiopathology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.95.22.13211

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.