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Novel Endogenous Antimicrobial Peptides

Nordahl, Emma LU (2009) In Lund University Faculty of Medicine Doctoral Dissertation Series 2009:51.
Abstract
Antimicrobial peptides serve as a first line of defence against invading microorganisms and are an essential part of our fast innate immune system. They are ancient molecules found in all classes of life. Antimicrobial peptides rapidly kill a broad spectrum of microbes and are immunomodulatory, i.e. having additional actions influencing inflammation and other innate immune responses. Results presented in this thesis demonstrate that proteases of common human pathogens degrade and inactivate the antimicrobial peptide LL-37, probably a strategy for bacteria to circumvent the action of antimicrobial peptides. Likewise, heavily sulphated glycosaminoglycans like dermatan sulphate and heparin were shown to bind to and inactivate LL-37.... (More)
Antimicrobial peptides serve as a first line of defence against invading microorganisms and are an essential part of our fast innate immune system. They are ancient molecules found in all classes of life. Antimicrobial peptides rapidly kill a broad spectrum of microbes and are immunomodulatory, i.e. having additional actions influencing inflammation and other innate immune responses. Results presented in this thesis demonstrate that proteases of common human pathogens degrade and inactivate the antimicrobial peptide LL-37, probably a strategy for bacteria to circumvent the action of antimicrobial peptides. Likewise, heavily sulphated glycosaminoglycans like dermatan sulphate and heparin were shown to bind to and inactivate LL-37. Furthermore, we demonstrate that structural characteristics associated with heparin affinity (cationicity and amphipathicity) may confer antimicrobial properties to any given peptide. Heparin-binding consensus sequences were proven to be active against Gram-positive bacteria, Gram-negative bacteria and the fungus Candida albicans. Similar results were obtained with synthetic peptides derived from heparin-binding sequences within endogenous proteins. In addition, novel antimicrobial activity and heparin-binding capacity were discovered for the anaphylatoxin C3a, generated during activation of the complement system, and the inactive derivative of C3a (C3adesArg), as well as shorter synthetic peptides from the molecule. Novel antimicrobial activity was also shown for the heparin binding and cell-binding domain 5 of high molecular weight kininogen, a substrate in the intrinsic pathway of coagulation. Interestingly, the peptide HKH20 (His479 His498) from this domain was active in high salt, and highly resistant to degradation by various bacterial proteases. The understanding that heparin binding is a property of many antimicrobial peptides may represent a powerful tool in the discovery of novel endogenous antimicrobial peptides from complex biological mixtures. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Hultmark, Dan, Department of Molecular Biology, Umeå University
organization
publishing date
type
Thesis
publication status
published
subject
keywords
D5, HK, C3a, HMWK, complement, heparin-binding, antibacterial, Antimicrbial peptide, AMP
in
Lund University Faculty of Medicine Doctoral Dissertation Series
volume
2009:51
pages
136 pages
publisher
Department of Clinical Sciences, Lund University
defense location
Belfragesalen D15, BMC,Sölvegatan 19, Lund
defense date
2009-05-19 09:15
ISSN
1652-8220
ISBN
978-91-86253-39-4
language
English
LU publication?
yes
id
f70ef602-cbb1-4b10-989e-965ecaa96a86 (old id 1390729)
date added to LUP
2009-05-05 13:50:03
date last changed
2016-09-19 08:44:51
@phdthesis{f70ef602-cbb1-4b10-989e-965ecaa96a86,
  abstract     = {Antimicrobial peptides serve as a first line of defence against invading microorganisms and are an essential part of our fast innate immune system. They are ancient molecules found in all classes of life. Antimicrobial peptides rapidly kill a broad spectrum of microbes and are immunomodulatory, i.e. having additional actions influencing inflammation and other innate immune responses. Results presented in this thesis demonstrate that proteases of common human pathogens degrade and inactivate the antimicrobial peptide LL-37, probably a strategy for bacteria to circumvent the action of antimicrobial peptides. Likewise, heavily sulphated glycosaminoglycans like dermatan sulphate and heparin were shown to bind to and inactivate LL-37. Furthermore, we demonstrate that structural characteristics associated with heparin affinity (cationicity and amphipathicity) may confer antimicrobial properties to any given peptide. Heparin-binding consensus sequences were proven to be active against Gram-positive bacteria, Gram-negative bacteria and the fungus Candida albicans. Similar results were obtained with synthetic peptides derived from heparin-binding sequences within endogenous proteins. In addition, novel antimicrobial activity and heparin-binding capacity were discovered for the anaphylatoxin C3a, generated during activation of the complement system, and the inactive derivative of C3a (C3adesArg), as well as shorter synthetic peptides from the molecule. Novel antimicrobial activity was also shown for the heparin binding and cell-binding domain 5 of high molecular weight kininogen, a substrate in the intrinsic pathway of coagulation. Interestingly, the peptide HKH20 (His479 His498) from this domain was active in high salt, and highly resistant to degradation by various bacterial proteases. The understanding that heparin binding is a property of many antimicrobial peptides may represent a powerful tool in the discovery of novel endogenous antimicrobial peptides from complex biological mixtures.},
  author       = {Nordahl, Emma},
  isbn         = {978-91-86253-39-4},
  issn         = {1652-8220},
  keyword      = {D5,HK,C3a,HMWK,complement,heparin-binding,antibacterial,Antimicrbial peptide,AMP},
  language     = {eng},
  pages        = {136},
  publisher    = {Department of Clinical Sciences, Lund University},
  school       = {Lund University},
  series       = {Lund University Faculty of Medicine Doctoral Dissertation Series},
  title        = {Novel Endogenous Antimicrobial Peptides},
  volume       = {2009:51},
  year         = {2009},
}