Respiratory ß-2-Microglobulin exerts pH dependent antimicrobial activity

Virulence

Paul Walther¹  Elsa Sanchez-Garcia²  Yasser B. Ruiz-Blanco²  Nico Preising³  Ludger Ständker³  Merve Karacan³  Armando A. Rodriguez⁴  Sebastian Wiese⁵  Armin Holch⁶  Barbara Spellerberg⁶  Richard Bauer⁶  Lia-Raluca Olari⁷  Jan Münch⁸  Christian Schumann⁹ 

[1] Central Facility for Electron Microscopy, Ulm University Medical Center, Ulm, German;Computational Biochemistry, Center of Medical Biotechnology, University of Duisburg-Essen, Essen, German;Core Facility Functional Peptidomics, Ulm University Medical Center, Ulm, German;Core Facility Functional Peptidomics, Ulm University Medical Center, Ulm, German;Core Unit Mass Spectrometry and Proteomics, Ulm University, Ulm, German;Core Unit Mass Spectrometry and Proteomics, Ulm University, Ulm, German;Institute of Medical Microbiology and Hygiene, University Hospital, Ulm, German;Institute of Molecular Virology, University Hospital, Ulm, German;Institute of Molecular Virology, University Hospital, Ulm, German;Core Facility Functional Peptidomics, Ulm University Medical Center, Ulm, German;Pneumology, Thoracic Oncology, Sleep and Respiratory Critical Care Medicine, Clinics Kempten-Allgäu, Kempten and Immenstadt, German;

关键词: ß2-microglobulin;    antimicrobial peptides;    innate immunity;    pH;    amyloid;   

DOI  :  10.1080/21505594.2020.1831367

来源: Taylor & Francis

【 摘 要 】

The respiratory tract is a major entry site for microbial pathogens. To combat bacterial infections, the immune system has various defense mechanisms at its disposal, including antimicrobial peptides (AMPs). To search for novel AMPs from the respiratory tract, a peptide library from human broncho-alveolar-lavage (BAL) fluid was screened for antimicrobial activity by radial diffusion assays allowing the efficient detection of antibacterial activity within a small sample size. After repeated testing-cycles and subsequent purification, we identified ß-2-microglobulin (B2M) in antibacterially active fractions. B2M belongs to the MHC-1 receptor complex present at the surface of nucleated cells. It is known to inhibit the growth of Listeria monocytogenes and Escherichia coli and to facilitate phagocytosis of Staphylococcus aureus. Using commercially available B2M we confirmed a dose-dependent inhibition of Pseudomonas aeruginosa and L. monocytogenes. To characterize AMP activity within the B2M sequence, peptide fragments of the molecule were tested for antimicrobial activity. Activity could be localized to the C-terminal part of B2M. Investigating pH dependency of the antimicrobial activity of B2M demonstrated an increased activity at pH values of 5.5 and below, a hallmark of infection and inflammation. Sytox green uptake into bacterial cells following the exposure to B2M was determined and revealed a pH-dependent loss of bacterial membrane integrity. TEM analysis showed areas of disrupted bacterial membranes in L. monocytogenes incubated with B2M and high amounts of lysed bacterial cells. In conclusion, B2M as part of a ubiquitous cell surface complex may represent a potent antimicrobial agent by interfering with bacterial membrane integrity.

【 授权许可】

CC BY