In Vivo Imaging Reveals an Essential Role for Neutrophils in Leishmaniasis Transmitted by Sand Flies

Science 15, 970 – 974 (2008)

Speaker: Wei-Ting Chang (張瑋庭)                                               Date: 2008.10.15

Commentator: Chih-Li Hsu, Ph.D. (胥直利 老師)               Place: Room 601

Abstract

        The bite of infected insects transmit numerous pathogens then caused many parasitic diseases, but the initial events that occur as pathogens are introduced by these vectors at sites of local feeding (wounds) are poorly understood. Leishmania transmission from infected sand fly bite is an emphatic experimental model for the study of early inflammatory response and relates processes. In this study, two-photon intravital microscopy (2P-IVM) and flow cytometry were used for observed a rapid and sustained infiltration of neutrophils at sand fly bite sites. The invaded neutrophils can efficiently phagocyte the Leishmania major (L. major) after sand fly bite or needle inoculation, but do not kill captured L. major. On the other hand, neutrophil depletion by treated with antibody that significantly reduced the number of viable L. major, as well as the incidence of parasites to establish productive infections. Thus, the early influx and persistence of neutrophils after sand fly transmission of L. major appears critical for the development of Leishmaniasis. The results of this study are relevant to the “Trojan horse” model of L. major infection, which postulates that uptake of infected neutrophils is a mechanism for “silent” entry of parasites into macrophages.

Reference

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