LL-37 Degradation by GCF: A Role for Porphyromonas gingivalis Proteinases?

Background: LL-37, composed of 37 amino acid residues, is an innate host defence peptide of the cathelicidin family. It is expressed by neutrophils, monocytes and epithelial cells and exhibits both anti-bacterial and immunomodulatory properties. LL-37 is however prone to proteolytic degradation by proteinases, thus potentially limiting its inherent host defence properties in the inflammatory milieu. Objectives: The present study was designed to determine whether LL-37 was degraded by components of gingival crevicular fluid (GCF) from healthy subjects or those with periodontitis. In addition, we aimed to deduce whether degradation of the peptide was accelerated in GCF samples which were determined to be positive for the periodontopathic bacterium Porphyromonas gingivalis. Methods: GCF and bacterial plaque samples, pre- and post non-surgical periodontal treatment, were collected from 4 individual sites in patients presenting with advanced periodontitis. In healthy subjects, GCF samples only were collected. Plaque samples were analysed by QPCR for the presence or absence of P. gingivalis. Pooled GCF samples from healthy sites; periodontitis sites which were P. gingivalis negative (Pg-); or periodontitis sites which were P. gingivalis positive (Pg+), were incubated with synthetic LL-37 for 0 – 180 min. The degradation products were then analysed by matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF MS). Results: LL-37 was not degraded when incubated with GCF from healthy subjects. In contrast, LL-37 was degraded after 30 min when incubated with Pg- GCF. However degradation of LL-37 was apparent after only 2 min incubation with Pg+ GCF and the parent molecule was almost completely degraded after 30 min. Conclusions: The rapid degradation of LL-37, particularly in Pg+ sites, highlights the limited role which this host defence peptide may play in the presence of biologically active proteinases. It also underscores a potent virulence mechanism of P. gingivalis used to circumvent innate host responses.

Comorbidity in severe asthma requiring systemic corticosteroid therapy: cross-sectional data from the Optimum Patient Care Research Database and the British Thoracic Difficult Asthma Registry

Objective: To determine the prevalence of systemic corticosteroid-induced morbidity in severe asthma.
Design: Cross-sectional observational study.Setting The primary care Optimum Patient Care Research Database and the British Thoracic Society Difficult Asthma Registry.
Participants: Optimum Patient Care Research Database (7195 subjects in three age- and gender-matched groups)—severe asthma (Global Initiative for Asthma (GINA) treatment step 5 with four or more prescriptions/year of oral corticosteroids, n=808), mild/moderate asthma (GINA treatment step 2/3, n=3975) and non-asthma controls (n=2412). 770 subjects with severe asthma from the British Thoracic Society Difficult Asthma Registry (442 receiving daily oral corticosteroids to maintain disease control).
Main outcome measures: Prevalence rates of morbidities associated with systemic steroid exposure were evaluated and reported separately for each group.
Results: 748/808 (93%) subjects with severe asthma had one or more condition linked to systemic corticosteroid exposure (mild/moderate asthma 3109/3975 (78%), non-asthma controls 1548/2412 (64%); p<0.001 for severe asthma versus non-asthma controls). Compared with mild/moderate asthma, morbidity rates for severe asthma were significantly higher for conditions associated with systemic steroid exposure (type II diabetes 10% vs 7%, OR=1.46 (95% CI 1.11 to 1.91), p<0.01; osteoporosis 16% vs 4%, OR=5.23, (95% CI 3.97 to 6.89), p<0.001; dyspeptic disorders (including gastric/duodenal ulceration) 65% vs 34%, OR=3.99, (95% CI 3.37 to 4.72), p<0.001; cataracts 9% vs 5%, OR=1.89, (95% CI 1.39 to 2.56), p<0.001). In the British Thoracic Society Difficult Asthma Registry similar prevalence rates were found, although, additionally, high rates of osteopenia (35%) and obstructive sleep apnoea (11%) were identified.

Conclusions: Oral corticosteroid-related adverse events are common in severe asthma. New treatments which reduce exposure to oral corticosteroids may reduce the prevalence of these conditions and this should be considered in cost-effectiveness analyses of these new treatments.