B. oleronius from Demodex mites linked to rosacea development

By Ingrid Grasmo

The bacterium Bacillus oleronius from Demodex mites may play a role in the development of rosacea, suggest study findings.

The findings support the use of antibiotic treatment for B. oleronius, which could result in a decline in the population of Demodex mites due to adverse effects on its metabolism.

"The identification of a role for bacteria in rosacea may facilitate the development of more effective therapies that target the bacterial population within Demodex mites," say Kevin Kavanagh (NUI Maynooth, Ireland) and co-authors.

For the study, the researchers used Western blot analysis to examine serum from 26 patients with erythematotelangiectic rosacea and 22 healthy controls for reactivity to B. oleronius proteins. Proteins to which the sera reacted were excised from gels, digested by trypsin, and then identified following liquid chromatography-mass spectrometry (LC/MS) analysis.

Analysis of the reactivity of each sera sample to 62kDa and 83kDa Bacillus proteins showed that 80% of rosacea patients had sera reactivity compared with 40% of controls. The majority (85.7%) of rosacea patients showed sera reactivity to the 62kDa protein, while 42.0% showed reactivity to the 83kDa protein, and 28.5% demonstrated activity to both proteins.

Of the healthy controls who showed reactivity to the Bacillus antigens, 88.8% reacted to the 62kDa antigen, while 22% showed sera reactivity to the 83kDa antigen, and 11% showed reactivity to both antigens.

When the team processed the 62kDa and 83kDa proteins by LC/MS analysis, they found that the former showed homology to a heat shock protein, groEL chaperonin - a highly immunogenic protein shown to provoke strong immune responses in humans.

Furthermore, the 83kDa protein was identified as showing homology to aconitate hydratase, which is a highly immunogenic protein increased in expression during periods of oxidative stress in bacteria.

"These results indicated that the two proteins to which rosacea patients' sera react are highly immunogenic and may a play a role in triggering an immune response, and thus inducing inflammation and tissue degradation," write the authors in the British Journal of Dermatology.

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