Antimicrobial peptides in nasal secretion and mucosa with respect to S. aureus colonisation in Wegener´s granulomatosis.

OBJECTIVES: Nasal S. aureus carrier rates are significantly higher in patients with Wegener's granulomatosis (WG) compared to healthy controls (HC), and nasal colonisation is a risk-factor for relapse. Antimicrobial peptides (AMP) are important defence molecules maintaining an intact barrier function. It is the aim of this study to see if there is a possible link between the nasal AMP pattern and S. aureus colonisation, a link which has not been investigated so far. METHODS: ELISA was applied to quantify LL-37 and hBD-3 concentrations in nasal secretions (14 WG patients, 13 HC) with and without nasal S. aureus colonisation. Immunohistochemistry was used to detect the cellular sources of AMP in the nasal mucosa. Functional analyses of primary nasal epithelial cell cultures (NEC) of these groups stimulated with S. aureus were performed. RESULTS: LL-37 was found in significantly higher concentrations in colonised individuals (WG: p=0.001; HC: p=0.014).Using immunohistochemistry, local cellular sources for AMP could be demonstrated. After stimulation with S. aureus, significantly higher concentrations of LL-37 and hBD-3 could be detected in the supernatant of NEC of WG patients (LL-37: p=0.001; hBD-3: p=0.001) and HC (LL-37: p=0.019; hBD-3: p=0.001). HBD-3 concentrations were significantly lower in the supernatant of stimulated NEC of WG patients compared to the NEC of HC (p=0.032), and the dynamic range of the hBD-3 answer was significantly smaller in WG compared to HC (p=0.016). CONCLUSIONS: The dynamic response towards challenges with microbes is dysregulated in WG, and this might be one reason for higher S. aureus colonisation rates in WG.

Antimicrobial peptides in nasal secretion and mucosa with respect to Staphylococcus aureus colonization in chronic rhinosinusitis with nasal polyps.

OBJECTIVE: Nasal carriage of Staphylococcus aureus in patients with chronic rhinosinusitis with nasal polyps (NP) is hypothesized to have pathophysiological impact on the disease. Antimicrobial peptides (AMP), especially human beta-defensin-3 (hBD-3) and LL-37, are an important part of the multifactorial defence against microorganisms in barrier organs like the nasal mucosa. The interaction of S. aureus colonization and AMP in nasal secretions and mucosa of NP were investigated in this study. PATIENTS AND METHODS: AMP were quantified in nasal secretions of 13 normal controls (NC) and 12 NP patients, each with and without S. aureus colonization, by ELISA. Immunohistochemistry was used to investigate the cellular sources of AMP in the nasal mucosa. To explore the AMP response of primary nasal epithelial cell cultures (NEC) towards S. aureus stimulation, a functional assay was established. RESULTS: AMP could be demonstrated in nasal secretions of all groups without differences in hBD-3 concentrations comparing S. aureus carriers vs. non-carriers. In NC, higher LL-37 concentrations were observed in S. aureus colonized as compared to non-colonized patients. This effect was not detectable in NP patients. Epithelial cells, submucosal glands and cells of the connective tissue could be identified as sources of AMP by immunohistochemistry. An AMP response of NEC towards S. aureus stimulation was detected in all groups. CONCLUSION: In NP patients, LL-37 response towards S. aureus colonization is disturbed while the ability of NEC to respond on S. aureus challenge is preserved. This deregulation of the nasal barrier could be involved in the multifactorial pathophysiology of NP.

Aberrant cytokine pattern of the nasal mucosa in granulomatosis with polyangiitis.

INTRODUCTION: In granulomatosis with polyangiitis (GPA), a complex autoimmune small-vessel vasculitis frequently associated with chronic necrotizing inflammation of the nasal mucosa, elevated nasal Staphylococcus (S.) aureus carrier rates are a risk factor for relapse. As cytokines are primarily involved in the regulation of defense against potentially pathogenic microorganisms, the aim of this study was to compare healthy individuals and GPA patients with respect to their baseline cytokine expression of nasal epithelial cells (NEC), which form the first barrier against such triggers. The ability of S. aureus to influence the nasal microenvironment's cytokine secretion was assessed by exemplary stimulation experiments. METHODS: Baseline expression of 19 cytokines of primary NEC of GPA patients and normal controls (NC) was quantified by a multiplex cytokine assay. Stimulation experiments were performed with supernatants of S. aureus and expression of interleukin-8 was determined by ELISA. RESULTS: In GPA, an altered pattern of baseline cytokine expression with significantly up-regulated G-CSF and reduced interleukin (IL)-8 concentrations was observed. Both NEC of GPA patients and NC responded to stimulation with S. aureus, but GPA patients displayed a significantly lower IL-8 secretion and a diminished dynamic range of response towards the stimulus. CONCLUSIONS: The data presented underline the hypothesis of a disturbed epithelial nasal barrier function in GPA. The dysregulated baseline expression of G-CSF and IL-8 and the reduced response to microbial stimulation may facilitate changes in the composition of the nasal flora and favour an imbalanced inflammatory response, which might be relevant for the disease course.

Subtyping of human cellular prion proteins and their differential solubility.

A human form of a prion disorder is the Creutzfeldt-Jakob disease. A hallmark of the disease is the accumulation of misfolded prion proteins (PrP(Sc)), which exist as heterogeneous subtypes. PrP(Sc) is formed by protein conversion from the host-encoded cellular prion (PrP(C)), which is expressed and modified to various isoforms. Little is known about variation in PrP(C); however, it is assumed that PrP(C) types play important roles in the formation of PrP(Sc). In this study, we separated distinct human PrP(C) subtypes on the basis of differential protein solubilities in detergent solutions. Single and sequential application of the detergents Triton X-100, octyl-glucopyranoside and CHAPS facilitated high solubility of glycosylated PrP(C) isoforms, whereas high proportions of nonglycosylated PrP(C) remained non-soluble. Most proteins became highly soluble with laurylsarcosine and sodium dodecyl sulphate. Our findings demonstrate that the solubility characteristics of heterogeneous PrP(C) overlap in human brains and convey distinct solubility subtypes. Differentiation by solubility experiments can therefore provide valuable information on prion protein composition, facilitate the separation of subtypes, and offer new prospects for conversion specificity of distinct isoforms.