Causes of Rosacea - Recent Scientific Discoveries Offer New ExplanationsCraig Kraffert, MD
Rosacea is a common age-old skin disorder with multiple clinical variants and skin findings including acne-like pimples, exaggerated facial flushing and persistent redness along with enlarged blood vessels and (sometimes) oil glands. Environmental triggers such as sun, wind, spicy foods, alcohol, hot beverages and stress, among others, have been identified. While these triggers all lead to facial flushing, the exact causal mechanisms of rosacea remain only partly understood. Current treatment options are not always based on targeting identified causes and are not always entirely satisfying for patients.
Scientific discoveries are slowly improving understanding of rosacea’s multiple causes. One recent study documented skin surface protein abnormalities associated with rosacea flares. Another explored the rosacea-stimulating effects of bacterial overgrowth within the sealed off gut of the common skin mite, Demodex folliculorum.
Kallikrein 5 and Cathelicidin
Two new rosacea related skin surface protein abnormalities have been identified. Potential treatments based on these new discoveries are being clinically investigated. There appears to be a unique interplay on the skin surface between a naturally occurring protein clipping molecule called kallikrein 5 and a naturally occurring antimicrobial peptide (protein fragment) called cathelicidin.
Patients with rosacea produce an excess of both kallikrein 5 and cathelicidin proteins. In the setting of rosacea, this excess cathelicidin is often of abnormal structure. This surface protein imbalance relates directly to rosacea severity. When levels and composition of kallikrein 5 and cathelicidin on the skin surface normalize, rosacea improves. Thus researchers have identified a new metric for assessing rosacea treatment effectiveness and a promising new target on which to focus future potential therapeutic advances.
Common Skin Mite, Demodex folliculorum
Another recent scientific discovery reveals a new twist on an old theory. For years dermatologists have noted that patients with rosacea often improve when given oral antibiotics such as doxycycline and topical antibiotics such as metronidazole. Yet, despite this reality, a causal link between bacteria and rosacea had never been conclusively established. Because of this, many had attributed the rosacea improving effects of antibiotics to their anti-inflammatory effects.
Recently, a bacterium, Bacillus oleronius, has been identified within the gut of the common skin mite Demodex folliculorum. These mites are generally much more numerous in rosacea sufferers. Because these mites build up all their metabolic debris internally without the benefits of defecation, the levels of this bacterium in older, engorged and dying mites are typically very high. When the mites die, their resident bacteria remain in the skin pores and appear to stimulate an immune response within the skin that clinically manifests as rosacea. The antibiotics that are effective against Demodex mites and/or Bacillus oleronius are associated with improvement in rosacea symptoms.
This is truly a significant revelation regarding possible causes of rosacea. This discovery 'mite' just turn out to be a key rosacea breakthrough. Based on these findings there may be a renewed focus on therapies that create a skin environment inhospitable to Demodex in a way that is safe and non-irritating to their human hosts.