Factors in rosacea pathogenesis clearer

[Guide]

The impact of other potential pathogens remains unsettled. For example, said Dr. Webster, European physicians accept completely that the Demodex folliculorum mite is the root of rosacea. "If you ask me, or many American dermatologists, it's less decided." Although D. folliculorum levels are elevated in rosacea, he explained, people can have heavy D. folliculorum colonization, but no rosacea, and vice versa. The fact that Demodex levels are highest in ETT rosacea counters the assumption that mites attack the hair follicles, causing inflammation and pimple formation, he added.

"The issue is confounded by the fact that the anti-mite drug Soolantra (topical ivermectin, Galderma) works well in rosacea. But no one has fulfilled Koch's postulates by showing that killing the Demodex improves rosacea; that Soolantra lowers Demodex levels; and that patients who resist Soolantra have Demodex levels that don't decrease with treatment." One cannot assume that topical ivermectin works in rosacea by killing Demodex, he said, because antibiotics such as doxycycline work in rosacea through many non-antibiotic effects. Topical ivermectin also has anti-inflammatory activity, he noted.

Also unclear, he said, is the contribution of Bacillus oleronius. This bacterium has been found to have antigens (chaperonin GroEL and aconitate hydratase) that excited the lymphocytes of patients with rosacea, but not in normal subjects.6 "It sounds like something's going on there. Also, the immune response to B. oleronius was found to be especially elevated in ocular rosacea. But we don't know that the antigens in this bug are unique to this bug. Much remains to be worked out. It's a stretch to conclude that the bug isolated from one mite of 40 studied is relevant. I'd be more convinced if these antigens are in Propionibacterium acnes or some known skin resident" that causes disease.

Factors in rosacea pathogenesis clearer
By John Jesitus
Dermatology Times, Dermatology, Clinical dermatology