Leishmania donovani suppresses activated protein 1 and NF-kappaB activation in host macrophages via ceramide generation: involvement of extracellular signal-regulated kinase.
In vitro infection of murine peritoneal macrophages with the protozoan Leishmania donovani has been found to alter the signaling parameters of the host. The present study indicates that the enhancement of intracellular ceramide level in macrophages after infection is a major event relating to macrophage dysfunction. We have previously demonstrated that increased ceramide synthesis in host macrophages was involved in the dephosphorylation of extracellular signal-regulated kinase (ERK). In the present study, we further show that downregulation of ERK by ceramide was found to be associated with the inhibition of activated protein 1 (AP-1) and NF-kappaB transactivation. Pharmacological inhibition of ceramide synthesis by Fumonisin B1 restored the induction of AP-1 and NF-kappaB DNA-binding activities in infected BALB/c macrophages. On the contrary, in the case of macrophages from the leishmaniasis-resistant C.D2 mice, L. donovani failed to induce sustained ceramide synthesis. Enhanced mitogen-activated protein kinase phosphorylation, AP-1 and NF-kappaB DNA-binding activity, and the generation of nitric oxide (NO) were observed in L. donovani-infected C.D2 macrophages. ERK activation was necessary for the activation of transcription factors AP-1 and NF-kappaB, NO generation, and restriction of the parasite burden in the resistant murine host macrophages. Hence, the induction of ceramide synthesis in host macrophages appears to be instrumental and one of the turning points leading to silencing of the macrophage antileishmanial responses.
Ghosh
Sanjukta
S
Department of Microbiology, Bose Institute, Calcutta 700 054, India.
Bhattacharyya
Sandip
S
Sirkar
Madhumita
M
Sa
Gouri Shankar
GS
Das
Tanya
T
Majumdar
Debashis
D
Roy
Syamal
S
Majumdar
Subrata
S
D000818:Animals; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism* / Q000494:pharmacology; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D007893:Leishmania donovani / Q000472:pathogenicity*; D007898:Leishmaniasis, Visceral / Q000469:parasitology / Q000503:physiopathology; D020935:MAP Kinase Signaling System; D017737:Macrophages, Peritoneal / Q000378:metabolism / Q000469:parasitology*; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism
D002518:Ceramides; D004791:Enzyme Inhibitors; D005419:Flavonoids; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one