Why Is Rosacea Considered to Be an Inflammatory Disorder?
The Primary Role, Clinical Relevance, and Therapeutic Correlations of Abnormal Innate Immune Response in Rosacea-Prone Skin
June 2012 | Volume 11 | Issue 6 | Original Article | 694 | Copyright © June 2012
The pathophysiology of rosacea has undergone renewed interest over the past decade, with a large body of evidence supporting the role
of an abnormal innate immune response in rosacea. Many mechanisms interact with the cutaneous innate immune system that may be
operative. A variety of potential triggers stimulate this immune detection system which is upregulated and hyper-responsive in facial skin
of patients with rosacea as compared to normal skin. Based on the most current data, two conclusions have been reached. First, the
major presentations of rosacea appear to be inflammatory dermatoses. Second, the presence of a microbial organism is not a primary
or mandatory component of the pathogenesis of rosacea. Available therapies for rosacea exhibit reported modes of action that appear
to correlate with the inhibition of inflammatory processes involved in the pathophysiology of at least some presentations of rosacea.
J Drugs Dermatol.2012;11(6):694-700.
Rosacea is well recognized globally as a common dermatologic
disorder encountered in clinical practice. Although
prevalence estimates vary depending on the population
evaluated and the methodology used to capture the diagnosis for
demographic or epidemiologic purposes, there is little disagreement
that at least the major presentations that have been classified
as rosacea are commonly encountered in clinical practice.1-4 For the
purposes of having a reasonably accepted "diagnostic language"
for discussion, the common presentations of rosacea were first
designated as subtypes in 2002, and subsequently in other references. 2 Among the four major subtypes, the two most common
are erythematotelangiectatic rosacea (ETR) and papulopustular rosacea
(PPR). Although rosacea has long been recognized as being
most common in patients with very fair skin with a reported prevalence
of up to 10% in individuals of Northern European or Celtic
heritage (Fitzpatrick Skin Type I-II), it has also been reported to affect
approximately 4% of individuals with darker skin types.5-7 To add,
there is some evidence that African Americans are more likely to be
affected by rosacea if one of the parents is of Northern European
ancestry.8 Nevertheless, a thorough evaluation of the prevalence
of rosacea, including a breakdown of individual subtypes or specific
presentations, has not been completed in patients with skin
of color (Fitzpatrick Skin Types IV-VI) or among different ethnicities
where darker skin types than Fitzpatrick I-II are predominant.
Clinical Differentiation of Common Presentations
Clinical features that characteristically manifest in ETR that are also
observed in many patients with PPR include diffuse central facial
erythema, telangiectasias, and associated symptoms (ie, stinging,
burning) and signs (ie, scaling, flaking, redness) of "skin sensitivity"
and stratum corneum (SC) permeability barrier impairment.1-5,8 PPR
differs clinically from ETR by the presence of inflammatory lesions
in PPR. The inflammatory lesions of PPR are commonly papules
and pustules that are most pronounced on the central face with associated
perilesional erythema, although some patients with PPR
may have few or many inflammatory lesions with little to no diffuse
central facial erythema that is not perilesional in nature.1-3,8-11