Expression and secretion of cathelicidin LL-37 in human epithelial cells after infection by Mycobacterium bovis Bacillus Calmette-Guérin.
The antimicrobial cathelicidin LL-37 is considered to play an important role in the innate immune response to tuberculosis infection. However, little is known about the induction and secretion of this antimicrobial peptide in A549 epithelial cells after infection with Mycobacterium bovis bacillus Calmette-Guérin (BCG), the world's most widely used tuberculosis vaccine. In this study, we investigated the effect of M. bovis BCG on LL-37 mRNA levels in A549 cells by real-time PCR and on protein levels by Western blotting. Treatment of cells with M. bovis BCG upregulates LL-37 mRNA expression in a dose- and time-dependent manner. The quantitative analysis of LL-37 gene expression correlated with our Western blotting results. Moreover, our results demonstrated that treatment of cells with the transcriptional inhibitor actinomycin D effectively inhibited in a concentration-dependent manner the ability of M. bovis BCG to induce LL-37 mRNA expression. Finally, inhibition of the MEK1/2 and p38 mitogen-activated protein kinase (MAPK) signaling pathways reduced M. bovis BCG-mediated LL-37 mRNA expression, a reduction that correlated with the observed high level of downregulation of LL-37 protein induction. Thus, these results indicate that the MEK1/2 and p38 MAPK signaling pathways play a critical role in the regulation of inducible LL-37 gene expression in A549 cells infected with M. bovis BCG.
Méndez-Samperio
Patricia
P
Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, IPN, Prol. Carpio y Plan de Ayala. México City, D.F. 11340, México. pmendezs@bios.encb.ipn.mx
Miranda
Elena
E
Trejo
Artemisa
A
D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis* / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003609:Dactinomycin / Q000378:metabolism; D004847:Epithelial Cells / Q000382:microbiology*; D020869:Gene Expression Profiling; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors; D009163:Mycobacterium bovis / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D054804:Cathelicidins
D023181:Antimicrobial Cationic Peptides; D003609:Dactinomycin; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D054804:Cathelicidins