Differential activity of innate defense antimicrobial peptides against Nocardia species

Siegbert Rieg,Eva Fähnrich,Benjamin Meier,Winfried V Kern,Hubert Kalbacher,Dirk Wagner,Anja Huth

doi:10.1186/1471-2180-10-61

Siegbert Rieg, Eva Fähnrich + Show 5 more

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https://doi.org/10.1186/1471-2180-10-61

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Abstract

BackgroundMembers of the genus Nocardia are ubiquitous environmental saprophytes capable to cause human pulmonary, disseminated and cutaneous nocardiosis or bovine mastitis. Innate immunity appears to play an important role in early defense against Nocardia species. To elucidate the contribution of antimicrobial peptides (AMPs) in innate defense against Nocardia, the activity of human α-defensins human neutrophil peptides (HNPs) 1-3, human β-defensin (hBD)-3 and cathelicidin LL-37 as well as bovine β-defensins lingual and tracheal antimicrobial peptides (LAP, TAP) and bovine neutrophil-derived indolicidin against four important Nocardia species was investigated.ResultsWhereas N. farcinica ATCC 3318 and N. nova ATCC 33726 were found to be susceptible to all investigated human and bovine AMPs, N. asteroides ATCC 19247 was killed exclusively by neutrophil-derived human α-defensins HNP 1-3 and bovine indolicidin. N. brasiliensis ATCC 19296 was found to exhibit complete resistance to investigated human AMPs and to be susceptible only to bovine indolicidin.ConclusionSelected AMPs are capable to contribute to the first line of defense against Nocardia, yet, susceptibility appears to vary across different Nocardia species. Obtained results of neutrophil-derived AMPs to possess the broadest antinocardial spectrum are remarkable, since nocardiosis is characterized by a neutrophil-rich infiltrate in vivo.

Highlights

Members of the genus Nocardia are ubiquitous environmental saprophytes capable to cause human pulmonary, disseminated and cutaneous nocardiosis or bovine mastitis
We found human a-defensins human neutrophil peptides (HNPs) 1-3 to be active, higher concentrations were needed with LD90 >32 μg/ml against N. farcinica and LD90 of 64 μg/ml against N. nova (Table 1)
HBD-3 and LL-37 were found to be more potent against N. nova than levofloxacin in equivalent concentrations

Summary

Introduction

Members of the genus Nocardia are ubiquitous environmental saprophytes capable to cause human pulmonary, disseminated and cutaneous nocardiosis or bovine mastitis. Innate immunity appears to play an important role in early defense against Nocardia species. Nocardia represent a genus of aerobic actinomycetes and belong to the family Mycobacteriaceae [1]. Gram-positive, filamentous, branching rods and can be found as ubiquitous environmental saprophytes in soil, dust, organic matter and water. At least 13 Nocardia species have been implicated in human infection with varying geographic prevalence throughout the world [3]. Major forms of Nocardia infection are pulmonary nocardiosis, disseminated and CNS nocardiosis, cutaneous/lymphocutaneous nocardiosis and mycetoma.

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