Immunantwort gegen Superantigene bei Staphylococcus aureus Carriern [Elektronische Ressource] = (Immune response against superantigens in Staphylococous aureus carriers) / vorgelegt von Silva Holtfreter

Silva Holtfreter

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• Gesundheit

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• Publié par: ernst-moritz-arndt-universitat_greifswald
• Publié le: 01 janvier 2006
• Nombre de lectures: 48
• Poids de l'ouvrage: 4 Mo

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Immunantwort gegen Superantigene bei Staphylococcus aureus Carriern
(Immune response against superantigens in carriers)


I n a u g u r a l d i s s e r t a t i o n
zur
Erlangung des akademischen Grades eines
Doktors der Naturwissenschaften
der
Mathematisch-Naturwissenschaftlichen Fakultät
der
Ernst-Moritz-Arndt-Universität Greifswald
vorgelegt von
Silva Holtfreter
geboren am 28.03.1980
in Güstrow
Greifswald, 22.12.2006
















































Dekan: Prof. Dr. rer. nat. Klaus Fesser


1. Gutachter: Prof. Dr. med. Barbara M. Bröker

2. Gutachter: Prof. Dr. rer. nat. Andreas Peschel


Tag der Promotion: 04.05.2007
CONTENTS
Contents
PART I I NTRODUCTION
General introduction and outline of the thesis............................................3
Chapter 1 Staphylococcus aureus colonization and infection.....................................5
Chapter 2 Staphylococcal Superantigens: Do they play a role in sepsis?
S. Holtfreter, B.M. Bröker. Arch Immunol Ther Exp (Warsz)
2005;53(1):13-27........................................................................................19
PART II RESULTS
Chapter 3 Clonal distribution of superantigen genes in clinical S. aureus isolates.
S. Holtfreter, D. Grumann, M. Schmudde, H. T. T. Nguyen, P. Eichler, B.
Strommenger, K. Kopron, S. Giedrys-Kalemba, A. Greinacher, W. Witte,
and B. M. Bröker. 2006. submitted.............................................................42
Chapter 4 Blood cell activation patterns induced by soluble products of
Staphylococcus aureus. Selleng, K., P. Eichler, M. Thiel, S. Holtfreter,
A.-K. Ziebandt, J. Koroschetz, A. Kruse, S. Engelmann, B. M. Bröker,
and A. Greinacher. 2006. submitted. ........................................................65
Chapter 5 egc-Encoded Superantigens from Staphylococcus aureus Are
Neutralized by Human Sera Much Less Efficiently than Are Classical
Staphylococcal Enterotoxins or Toxic Shock Syndrome Toxin.
S. Holtfreter, K. Bauer, D. Thomas, C. Feig, V. Lorenz, K. Roschack, E.
Friebe, K. Selleng, S. Lovenich, T. Greve, A. Greinacher, B. Panzig, S.
Engelmann, G. Lina, and B. M. Bröker. 2004. Infect. Immun. 72:4061-
4071. ..........................................................................................................83
Chapter 6 Similar T cell activating properties of egc and classical superantigens.
submitted.
D. Grumann, S. Holtfreter, C. Kohler, S. Engelmann, M. Hecker, and B.
M. Bröker. 2006. submitted........................................................................98
Chapter 7 Staphylococcus aureus Carriers Neutralize Superantigens by Antibodies
Specific for their Colonizing Strain; a Potential Explanation for their
Improved Survival in Severe Sepsis.
S. Holtfreter, K. Roschack, P. Eichler, K. Eske, B. Holtfreter, C. Kohler,
S. Engelmann, M. Hecker, A. Greinacher, and B. M. Bröker. 2006. J
Infect Dis 193:1275-80...............................................................................109
1 CONTENTS
PART III SUMMARY
Chapter 8 Summary and discussion...........................................................................116
PART IV APPENDIX
Summary....................................................................................................i
Zusammenfassung.....................................................................................iii
Nomenclature of superantigen-encoding mobile genetic elements ..........v
Abbreviations.............................................................................................vi
Publications................................................................................................viii
Conferences...............................................................................................ix
Acknowledgements/Danksagung...............................................................xi
Eidesstattliche Erklärung............................................................................xiii
Curriculum vitae.........................................................................................xiv

2
GENERAL INTRODUCTION AND OUTLINE OF THE THESIS
Staphylococcus aureus colonises the anterior nares of circa 35% of the healthy population.
However, once the mucosal or skin barrier is broken, e.g. by a lesion of the skin or mucous
membranes, catheters insertions and foreign bodies, the bacteria can invade virtually every
human tissue and cause a broad spectrum of diseases, ranging from mild skin and wound
infections to life-threatening conditions, such as endocarditis, pneumonia and sepsis. To
date, S. aureus is the most common cause of nosocomial infections and the species is
1becoming increasingly resistant to antibiotics . In several industrialised nations, including
parts of Europe, the USA and Japan, 40-60% of all nosocomial S. aureus strains are resis-
2tant to methicillin (methicillin-resistant S. aureus; MRSA) . Especially the emergence of high-
level vancomycin-resistant isolates is alarming and threatens to throw staphylococcal therapy
3back to the pre-antibiotic age . As a consequence, effective measures to prevent and treat
staphylococcal infections are urgently needed.
It is well established that nasal colonisation with S. aureus is a major risk factor for staphylo-
4coccal infections . Compared to noncarriers, S. aureus carriers have a four-fold increased
5risk of acquiring an S. aureus bacteraemia, which is mostly caused by the colonising strain .
Intriguingly, once carriers develop an S. aureus bacteraemia, their mortality is
6lower than in noncarriers . These observations stress the importance of host factors, such as
the immune response, for the outcome of S. aureus-host interactions. However, despite their
high prevalence and the medical need to prevent S. aureus infections in the human popula-
tion, our understanding of the role of the immune system in staphylococcal colonisation and
4infection is still limited . Therefore, a major task of staphylococcal research is the elucidation
of the immunological mechanisms active in S. aureus nasal carriage and infection. This
knowledge is a prerequisite for the development of new preventive and therapeutic strate-
gies, such as active and passive antistaphylococcal vaccination.
The main aim of this thesis was to investigate adaptive immune responses which S. aureus
carriers raise against their colonising strain. In our studies we used superantigens (SAgs) as
indicator antigens for three reasons. Firstly, SAgs are clinically important virulence factors.
They cause the toxic shock syndrome, and are probably also involved in the pathogenesis of
staphylococcal sepsis. Secondly, the SAg gene repertoire of clinical S. aureus isolates is
highly variable, due to their localisation on mobile genetic elements. This enabled us to com-
pare strain-specific immune responses in S. aureus carriers and noncarriers. Finally, by ex-
ploiting the T cell-mitogenic activity of SAgs, we could easily assess neutralising antibody
capacities of different sera in a proliferation assay.
The scope of the present thesis was
i) to analyse the prevalence of SAg genes among colonising and invasive isolates
and to correlate it with the clonal background,
ii) to determine the anti-SAg antibody profiles in healthy individuals and
iii) to compare strain-specific antibody responses against staphylococcal SAgs in
S. aureus carriers and noncarriers.
3
Chapter 1 provides an overview about S. aureus nasal carriage and the associated infection
risk, briefly describes S. aureus genomics, discusses determinants of staphylococcal viru-
lence and finally summarises the current knowledge about the role of the innate and adaptive
immune system in staphylococcal colonisation and infection. Chapter 2 introduces staphylo-
coccal SAgs, which are in the focus of this thesis. This review gives an overview about the
localisation of all 19 SAg genes within the staphylococcal genome and discusses their impli-
cations in sepsis.
In Chapter 3, the highly diverse SAg gene repertoire of nasal and blood culture isolates from
Western Pomerania was analysed using multiplex-PCR and correlated with the clonal back-
ground. Chapter 4 elucidates the heterogeneous activation patterns of different blood cell
types induced by various staphylococcal soluble factors. Both studies emphasise the impor-
tance of strain-specific analyses of host-pathogen interactions during colonisation and
infection.
Once the SAg gene repertoire of clinical strains was determined, we analysed the antibody
profiles against staphylococcal SAgs in healthy individuals (Chapter 5). Antibodies against
SAgs of the enterotoxin gene cluster (egc) were detected only rarely, which is surprising
because egc SAgs are the most prevalent SAgs in S. aureus. Therefore, we tested whether
the observed “egc gap” in the antibody profiles was du