Macrolide Treatment Inhibits Pseudomonas aeruginosa Quorum Sensing in Non-Cystic Fibrosis Bronchiectasis. An Analysis from the Bronchiectasis and Low-Dose Erythromycin Study Trial.

RATIONALE: The mechanism by which low-dose macrolide therapy reduces exacerbations in non-cystic fibrosis bronchiectasis is not known. Pseudomonas aeruginosa quorum sensing controls the expression of a range of pathogenicity traits and is inhibited by macrolide in vitro. Quorum sensing inhibition renders P. aeruginosa less pathogenic, potentially reducing its contribution to airway damage. OBJECTIVES: The aim of this study was to determine whether long-term low-dose erythromycin inhibits P. aeruginosa quorum sensing within the airways of patients with non-cystic fibrosis bronchiectasis. METHODS: Analysis was performed on induced sputum from P. aeruginosa-positive subjects at recruitment to the BLESS (Bronchiectasis and Low-Dose Erythromycin Study) trial and after 48 weeks of treatment with erythromycin or placebo. To avoid changes in gene expression during culture, bacterial mRNA was extracted directly from sputum, and the relative expression of functionally critical quorum sensing genes was determined by quantitative polymerase chain reaction. MEASUREMENTS AND MAIN RESULTS: In keeping with the BLESS study, a significant reduction in total exacerbations was seen in this subgroup (placebo: 6, [interquartile range (IQR), 4-8]; erythromycin: 3, [IQR, 3-4]; P = 0.008; Mann-Whitney test). Erythromycin therapy did not change P. aeruginosa bacterial load determined by polymerase chain reaction. A significant reduction was observed in the expression of the quorum sensing genes, lasR (erythromycin: fold change, 0.065 [IQR, 0.01-0.85], n = 11; placebo: fold change, 1.000 [IQR, 0.05-3.05]; P = 0.047, Mann-Whitney U test) and pqsA (erythromycin: fold change, 0.07 [IQR, 0.02-0.25]; placebo: fold change, 1.000 [IQR, 0.21-4.31], P = 0.017, Mann-Whitney U test), after 48 weeks of erythromycin, compared with placebo. CONCLUSIONS: We demonstrate inhibition of P. aeruginosa quorum sensing within the airways of patients with non-cystic fibrosis bronchiectasis receiving long-term, low-dose erythromycin, without a reduction in bacterial load, representing a potential mechanism of therapeutic impact beyond a classical antimicrobial or antiinflammatory pathway.

High resolution spatial mapping of brominated pyrrole-2-aminoimidazole alkaloids distributions in the marine sponge Stylissa flabellata via MALDI-mass spectrometry imaging.

A number of pharmacologically active brominated pyrrole-2-aminoimidazole (B-P-2-AI) alkaloids have been isolated from several families of marine sponges, including those belonging to the genus Stylissa. In the present study, MALDI mass spectrometry imaging (MALDI-imaging) was applied to determine the spatial distribution of B-P-2-AIs within 20 µm cross sections of S. flabellata. A number of previously characterised B-P-2-AIs were readily identified by MALDI-imaging and confirmed by MS-MS and NMR profiling. Unknown B-P-2-AIs were also observed. Discrete microchemical environments were revealed for several B-P-2-AIs including dibromophakellin which was localised within the external pinacoderm and internal network of choanoderm chambers. Additionally, dibromopalau'amine and konbu'acidin B were also found to be confined to the choanoderm, while sceptrin was found to be highly abundant within the mesohyl. Further brominated compounds of unknown structure were also observed to have distinct localisation in both choanoderm chambers and the pinacoderm. These findings provide insights into the chemical ecology of S. flabellata, as most B-P-2-AIs were found on highly exposed surfaces, where they may act to prevent pathogens, predation and/or biofouling. Moreover this study demonstrates the power of MALDI-imaging to visualise the location of a range of metabolites in situ and to characterise compounds by MS-MS directly from intact specimens without the need for extraction. These methodologies facilitate selective targeting of micro-regions of sponge to screen for symbiotic microbial candidates or genes that may be involved in the production of the correlated compounds, and may represent a change in paradigm for natural product drug development.

Composition of LDL particle discriminates between hypercholesterolaemic persons with and without symptoms of coronary heart disease.

BACKGROUND: It is well known that high total and LDL cholesterol concentrations are not prerequisites for ischemic heart disease. This study aimed to differentiate between patients with coronary heart symptoms and healthy subjects with high cholesterol concentrations, using other potential risk factors such as oxidation state, body iron status and the oxidative state of the LDL particle. METHODS: Healthy persons were divided in low cholesterol (<6 mmol/L) (LC) and high cholesterol (> or =6 mmol/L) (HC) groups. An additional group consisted of patients with symptoms of coronary heart disease (P). The lipid profile, body iron status, plasma antioxidants and LDL oxidation status were measured. RESULTS: No significant differences could be observed between the LC and HC groups or between the lipid profiles, plasma antioxidants and parameters of body iron status of the HC and patient groups. Some parameters measured on isolated LDL differed between the HC and patient groups, such as LDL oxidative potential (134.47 vs 93.70 min) and LDL alpha-tocopherol (21.83 vs 11.73 micro mol/mmol cholesterol). CONCLUSION: The oxidative state of the LDL particle discriminated between patients with symptoms of coronary heart disease and hypercholesterolaemic persons without symptoms of coronary heart disease.

Beneficial effects of blood donation on high density lipoprotein concentration and the oxidative potential of low density lipoprotein.

According to some authors blood donors have a lower risk of cardiovascular incidents. This may be associated with the risk of cardiovascular disease reported by some authors, as well as with the oxidative changes caused by iron. The aim of this study was to determine, what happens to some of the factors contributing to atherosclerosis after the lowering of body iron. Blood was drawn from 23 healthy males after overnight fasting and the parameters described below determined. These persons donated blood (500 ml) on three occasions with 6 weeks intervals. Six to eight weeks after the third and final donation, blood was again drawn after overnight fasting and the following parameters measured for the second time: various parameters of body iron; lipid profile; anti-oxidants; and oxidative parameters of low density lipoprotein (LDL). Blood donation has various beneficial effects, such as increasing high density lipoprotein (HDL) and apoA; a higher oxidative potential of LDL; a lower level of LDL peroxidation resulting in a LDL particle with a higher oxidative potential, and a higher NO(3) concentration. We conclude that blood donation, and thereby a lowered body iron concentration, is an effective way to increase the oxidative potential of LDL, as well as the HDL and apoA concentrations.