Antimycobacterial Agent Based on mRNA Encoding Human β-Defensin 2 Enables Primary Macrophages To Restrict Growth ofMycobacterium tuberculosis

Abstract

Human macrophages are hosts for Mycobacterium tuberculosis, the causative agent of tuberculosis, which killed approximately 1.87 million people in 1997. Human alveolar macrophages do not express ␣-or ␤-defensins, broad-spectrum antimicrobial peptides which are expressed in macrophages from other species more resistant to infection with M. tuberculosis. It has been previously reported that M. tuberculosis is susceptible to killing by defensins, which may explain the difference in resistance. Defensin peptides have been suggested as a possible therapeutic strategy for a variety of infectious diseases, but development has been hampered by difficulties in their large-scale production. Here we report the cellular synthesis of human ␤-defensin 2 via highly efficient mRNA transfection of human macrophages. This enabled mycobactericidal and mycobacteristatic activity by the macrophages. Although human macrophages are difficult to transfect with plasmid vectors, these studies illustrate that primary macrophages are permissive for mRNA transfection, which enabled expression of a potentially therapeutic protein.

Interplay between antibacterial effectors: A macrophage antimicrobial peptide impairs intracellular Salmonella replication

“…Ectopic expression of foreign peptides has suggested that peptides can be important mediators of innate immune control of bacterial pathogens. Human LL-37 augments mouse lung defense against Pseudomonas aeruginosa (34), human defensin 5 in the intestine makes mice more resistant to oral challenge with S. typhimurium (35), and human defensin expression in macrophages controls replication of pathogens such as Mycobacterium tuberculosis (36,37). Here, we show the expression, activation, and activity of an endogenous cationic peptide within macrophages, an important target cell of many significant intracellular pathogens.…”

Innate immunity in aging: impact on macrophage function

“…Whereas Duits et al . (2002) presented data indicating the presence of two human β -defensins, hDB-1 and -2, within unactivated alveolar macrophages, Kisich et al . (2001) did not find any evidence for the presence of either α -or β -defensin in activated alveolar macrophages.…”

Periodontal Disease and Gingival Innate Immunity – Who Has the Upper Hand?

“…AMPs as therapeutics against microbes would be promising because the target of AMPs are the bacterial membrane, thus to combat AMPs the bacteria would need to redesign its membrane, which would be a "costly" solution for most species (Zasloff 2002). The possibility of alleviating bacterial infections related to cystic fibrosis through increasing physiological levels of LL-37, or re-engineering human macrophages to express beta-defensins to enhance efficacy against Mycobacterium tuberculosis have been proposed (Bals, Weiner et al 1999;Kisich, Heifets et al 2001). However, limitations as an effective therapeutic are stalled by high production costs and the susceptibility to proteolytic degradation, a mechanism which microbial pathogens secrete proteases to counter-measure the target of AMPs (Peters, Shirtliff et al 2010).…”