title: Cathelicidin is involved in the intracellular killing of mycobacteria in macrophages.
abstract: Macrophages have been shown to kill Mycobacterium tuberculosis through the action of the antimicrobial peptide cathelicidin (CAMP), whose expression was shown to be induced by 1,25-dihydroxyvitamin D3 (1,25D3). Here, we investigated in detail the antimycobacterial effect of murine and human cathelicidin against Mycobacterium smegmatis and M. bovis BCG infections. We have synthesized novel LL-37 peptide variants that exhibited potent in vitro bactericidal activity against M. smegmatis, M. bovis BCG and M. tuberculosis H37Rv, as compared with parental peptide. We show that the exogenous addition of LL-37 or endogenous overexpression of cathelicidin in macrophages significantly reduced the intracellular survival of mycobacteria relative to control cells. An upregulation of cathelicidin mRNA expression was observed that correlated with known M. smegmatis killing phases in J774 macrophages. Moreover, RNAi-based Camp knock-down macrophages and Camp(-/-) bone marrow derived mouse macrophages were significantly impaired in their ability to kill mycobacteria. M. smegmatis killing in Camp(-/-) macrophages was less extensive than in Camp(+/+) cells following activation with FSL-1, an inducer of cathelicidin expression. Finally we show that LL-37 and 1,25D3 treatment results in increase in colocalization of BCG-containing phagosomes with lysosomes. Altogether, these data demonstrate that cathelicidin plays an important role in controlling intracellular survival of mycobacteria.
authors.affiliation: School of Biotechnology, Campus-11, KIIT University, Bhubaneswar 751024, Orissa, India. asonawane@kiitbiotech.ac.in
authors.forename: Avinash
authors.initials: A
authors.lastname: Sonawane
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Santos
authors.forename: Bibhuti B
authors.initials: BB
authors.lastname: Mishra
authors.forename: Prajna
authors.initials: P
authors.lastname: Jena
authors.forename: Cinzia
authors.initials: C
authors.lastname: Progida
authors.forename: Ole E
authors.initials: OE
authors.lastname: Sorensen
authors.forename: Richard
authors.initials: R
authors.lastname: Gallo
authors.forename: Rui
authors.initials: R
authors.lastname: Appelberg
authors.forename: Gareth
authors.initials: G
authors.lastname: Griffiths
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000235:genetics / Q000494:pharmacology*; D001688:Biological Products / Q000494:pharmacology*; D002478:Cells, Cultured; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D018345:Mice, Knockout; D050296:Microbial Viability / Q000187:drug effects*; D009163:Mycobacterium bovis / Q000276:immunology* / Q000502:physiology; D020102:Mycobacterium smegmatis / Q000276:immunology* / Q000502:physiology; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D001688:Biological Products; D011994:Recombinant Proteins; D054804:Cathelicidins