Demodex-associated bacterial proteins induce neutrophil activation

• Published in: British journal of dermatology (1951) Vol. 166; no. 4; pp. 753 - 760
• Main Authors: O'Reilly, N., Bergin, D., Reeves, E.P., McElvaney, N.G., Kavanagh, K.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.04.2012; Wiley-Blackwell
• Subjects: Animals; Antigens, Bacterial - immunology; Antimicrobial Cationic Peptides - metabolism; Antimicrobial peptides; Bacillus; Bacillus - immunology; Bacterial Proteins - pharmacology; Biological and medical sciences; cathelicidins; Cell activation; Cell Degranulation - immunology; Cell Migration Assays, Leukocyte; Cell Movement - immunology; Collagen; Cytokines - biosynthesis; Degranulation; Demodex; Dermatology; Electrophoresis, Polyacrylamide Gel; Enzyme-Linked Immunosorbent Assay; Enzymes; Erythema; Humans; Immune response; Inflammation; Interleukin 8; Leukocyte migration; Leukocytes (neutrophilic); Liquid chromatography; Matrix metalloproteinase; Matrix Metalloproteinase 9 - metabolism; Medical sciences; Mite Infestations - immunology; Mites; Neutrophil Activation - drug effects; Neutrophils - metabolism; Rosacea; Rosacea - immunology; Skin; Tumor necrosis factor- alpha; Infection; Bacteriosis; Neutrophil; Dermatology; Protein
• ISSN: 0007-0963; 1365-2133
• DOI: 10.1111/j.1365-2133.2011.10746.x

Summary Background  Patients with rosacea demonstrate a higher density of Demodex mites in their skin than do controls. A bacterium isolated from a Demodex mite from a patient with papulopustular rosacea (PPR) was previously shown to provoke an immune response in patients with PPR or ocular rosacea, thus suggesting a possible role for bacterial proteins in the aetiology of this condition. Objectives  To examine the response of neutrophils to proteins derived from a bacterium isolated from a Demodex mite. Methods  Bacterial cells were lysed and proteins were partially purified by ÄKTA fast protein liquid chromatography. Isolated neutrophils were exposed to bacterial proteins and monitored for alterations in migration, degranulation and cytokine production. Results  Neutrophils exposed to proteins from Bacillus cells demonstrated increased levels of migration and elevated release of matrix metalloprotease 9, an enzyme known to degrade collagen, and cathelicidin, an antimicrobial peptide. In addition, neutrophils exposed to the bacterial proteins demonstrated elevated rates of interleukin 8 and tumour necrosis factor‐α production. Conclusions  Proteins produced by a bacterium isolated from a Demodex mite have the ability to increase the migration, degranulation and cytokine production abilities of neutrophils. These results suggest that bacteria may play a role in the inflammatory erythema associated with rosacea.