Katrin Pütsep Project
Bacterial-host homeostasis in the oral cavity and gastrointestinal tract
Mammals have evolved in the presence of microorganisms and hence a symbiotic relationship has developed which allows a microbiota to reside in the host while preventing opportunistic pathogens to gain foothold. Our hypothesis is that antimicrobial peptides and proteins contribute to the control of this homeostasis.
The intestinal mucosal epithelium consists of a single cell layer, which is colonized by a resident microbiota. This epithelium is rich in host derived antimicrobial peptides and proteins, which has the capacity to kill bacteria without involvement of strong inflammatory, tissue damaging reactions. We have previously shown that the repertoire and expression of antimicrobial peptides change following birth, increases in the mouse small intestine from gut to colon and that the secreted intestinal antimicrobial components are retained by the mucus layer, thus contributing to the protective shield. Our present focus is to further investigate the regulation and different biological aspects of these intestinal antimicrobial peptides using innate defence gene knock-out models. The clinical relevance is stressed by the fact that many patients with inflammatory bowels diseases present with low levels of intestinal peptides and highly colonized mucus layers.
Contrary to the intestinal epithelium, the homeostasis of the oral cavity is dependent on protection by functional neutrophils. Individuals with neutrophil dysfunction or severe congenital neutropenia (SCN or Kostmann syndrome) are at high risk for periodontal disease and tooth loss. Patients with SCN receive life-saving G-CSF treatment to elevate their neutrophil levels. We previously discovered that their neutrophils were deficient in the antimicrobial peptides LL-37 and exhibited lower levers of the alpha-defensins HNP 1-3. In order to the determine the impact of antimicrobial peptides to oral pathogen control we are currently investigating their oral health, in relation to the local microbiota composition using 16SrRNA-gene sequencing and innate defence molecule expression.
Genetic studies have linked mutations in the genes for neutrophil elastase and the anti-apoptotic protein HAX1 to the SCN phenotype, while some patients display neither mutation. However, the neutrophil LL-37 transcript deficiency is a common denominator. There are reports on additional defects in the neutrophil functions of patients with SCN. Present work aims to unravel the mechanisms behind these neutrophil dysfunctions using proteomics with HPLC, 2-DE and mass-spectrometry combined with high-throughput DNA sequencing.
Cinobufagin Modulates Human Innate Immune Responses and Triggers Antibacterial Activity.
PLoS ONE 2016 ;11(8):e0160734
Essential Oils from Ugandan Aromatic Medicinal Plants: Chemical Composition and Growth Inhibitory Effects on Oral Pathogens.
Evid Based Complement Alternat Med 2015 ;2015():230832
Novel STAT3 mutation causing hyper-IgE syndrome: studies of the clinical course and immunopathology.
J. Clin. Immunol. 2014 May;34(4):469-77
Interleukin-13-mediated paneth cell degranulation and antimicrobial peptide release.
J Innate Immun 2014 ;6(4):530-41
Oral bacterial community dynamics in paediatric patients with malignancies in relation to chemotherapy-related oral mucositis: a prospective study.
Clin. Microbiol. Infect. 2013 Dec;19(12):E559-67
Pretherapeutic plasma pro- and anti- inflammatory mediators are related to high risk of oral mucositis in pediatric patients with acute leukemia: a prospective cohort study.
PLoS ONE 2013 ;8(5):e64918
CRS-peptides: unique defense peptides of mouse Paneth cells.
Mucosal Immunol 2012 Jul;5(4):367-76
Mutations in the ELANE gene are associated with development of periodontitis in patients with severe congenital neutropenia.
J. Clin. Immunol. 2011 Dec;31(6):936-45
Vitamin D3 induces pro-LL-37 expression in myeloid precursors from patients with severe congenital neutropenia.
J. Leukoc. Biol. 2008 Nov;84(5):1279-86
Secreted enteric antimicrobial activity localises to the mucus surface layer.
Gut 2008 Jun;57(6):764-71
Increased diversity of intestinal antimicrobial peptides by covalent dimer formation.
Nat. Immunol. 2004 Aug;5(8):836-43
Deficiency of antibacterial peptides in patients with morbus Kostmann: an observation study.
Lancet 2002 Oct;360(9340):1144-9