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Cytopathic changes and pro‐inflammatory cytokines induced by Naegleria fowleri trophozoites in rat microglial cells and protective effects of an anti‐Nfa1 antibody
Author(s) -
OH Y.H.,
JEONG S.R.,
KIM J.H.,
SONG K.J.,
KIM K.,
PARK S.,
SOHN S.,
SHIN H.J.
Publication year - 2005
Publication title -
parasite immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 75
eISSN - 1365-3024
pISSN - 0141-9838
DOI - 10.1111/j.1365-3024.2005.00799.x
Subject(s) - naegleria fowleri , biology , pseudopodia , cytotoxicity , microbiology and biotechnology , antibody , immunocytochemistry , microglia , cell culture , immunology , meningoencephalitis , inflammation , cell , in vitro , biochemistry , genetics , endocrinology
SUMMARY Naegleria fowleri , a free‐living amoeba, causes fatal primary amoebic meningoencephalitis in experimental animals and humans. The nfa1 gene (360 bp) was previously cloned from a cDNA library of pathogenic N. fowleri by immunoscreening, and produced a 13·1‐kDa recombinant protein that showed pseudopodia‐specific localization by immunocytochemistry. On the basis of an idea that the pseudopodia‐specific Nfa1 protein seems to be involved in the pathogenicity of N. fowleri , the cytopathic activity of N. fowleri trophozoites co‐cultured with rat microglial cells was observed, and the effects of an anti‐Nfa1 antibody in a co‐culture system were elucidated. Using light, scanning and transmission electron microscopy, it was seen that N. fowleri trophozoites in contact with microglial cells produced vigorous pseudopodia and a food‐cup structure. Microglial cells were destroyed by N. fowleri trophozoites as seen from necrotic cell death in a time‐dependent manner. In a 51 Cr release assay, N. fowleri showed 17·8%, 24·9%, 54·6% and 98% cytotoxicity against microglial cells at 3, 6, 12 and 24 h post‐incubation, respectively. However, when anti‐Nfa1 antibody was added in a coculture system, N. fowleri cytotoxicity was reduced to 15·5%, 20·3%, 46·7% and 66·9%, respectively. Moreover, microglial cells co‐cultured with N. fowleri trophozoites secreted the pro‐inflammatory cytokines, TNF‐α, IL‐1β and IL‐6. In the presence of anti‐Nfa1 antibody, the secretion of TNF‐α was slightly, but not significantly, decreased.