Rosacea is a chronic, inflammatory skin disorder that commonly affects middle-aged people of Celtic extraction. Currently, it affects 13% of the Irish population. Patients with rosacea frequently complain of dry, sensitive skin, suggesting an abnormality of their skin barrier function. The cause of this complex disease is incompletely understood.

A possible aetiological agent is the ubiquitous Demodex mite that resides within the sebaceous follicles in the face. No visible reaction occurs when mites are present in normal numbers. However, numbers of facial mites are increased in rosacea patients. Rosacea responds to antibiotic treatment but their mode of action is unknown.

Current Research

Rosacea Patients and the Effect of Antibiotics

Lead Investigator

Prof Frank Powell
UCD Charles Institute of Dermatology
Research profile

Research Focus

Although the cause of rosacea is unknown, the inflammatory lesions associated with the disease are effectively treated with topical and systemic antibiotics. However, repeated courses of antibiotics are required and maintenance therapy with topical antibiotics is necessary indefinitely. This approach to treatment is not ideal either for the patient or the community exposed to the risk of resistant organisms.

We believe that the cutaneous microenvironment in the skin of rosacea patients is different, allowing an increase in the population of Demodex mites and resulting in an inflammatory reaction that leads to the clinical features of rosacea.

Dr Noreen Lacey PhD is the principal scientist working on this project to characterise, clinically and biochemically, the facial milieu in rosacea patients pre- and post-antibiotic therapy in vivo. This may help to identify the factors that allow an increase in the Demodex mite population. The team will also study the effects of antibiotics used in the treatment of rosacea patients on human sebocytes in the laboratory. By understanding the mode of action of antibiotic treatment, we hope to define other non-antibiotic therapies for rosacea patients by potentially using sebum modifying treatments. We also want to decipher how the Demodex mites induce an immune response in rosacea patients.

Fatty Acid Composition of Sebum in Rosacea Patients

Lead Investigators

  • Dr Lorraine Brennan
  • UCD Conway Institute of Biomolecular & Biomedical Research
  • Research Profile


Research Focus

Clinical studies by Professor Powell and Dr. Síona Ní Raghallaigh (Charles Institute Clinical Research Fellow) found no abnormality in the quantity of sebum on the skin surface, despite markedly reduced hydration levels in patients with a subtype of rosacea called papulopustular rosacea. They proposed that it may be the quality of sebum that plays a role in this disorder.

In conjunction with Dr Lorraine Brennan, the fatty acid composition of this sebum was analysed by gas chromatography-mass spectrometry in UCD Conway Institute. Saturated, very long chain fatty acids were found in the sebum of patients with papulopustular rosacea in lesser concentrations as compared with controls. Despite only being present in small quantities in sebum, these very long-chain fatty acids are important components of sebum and play a significant role in skin barrier function.

Dr Brennan and Prof Powell continue to explore new ventures in the area of skin lipid research and their collaboration highlights the importance of the continued medical and scientific interface.

Ní Raghallaigh, S., Bender, K., Lacey, N., Brennan, L. and Powell, F.C. (2012) The fatty acid profile of the skin surface lipid layer in papulopustular rosacea. British Journal of Dermatology, 166: 279–287. doi: 10.1111/j.1365-2133.2011.10662.x