Pathogenesis And Treatment Of Acne And Rosacea
Acne, one of the most common skin diseases, affects approximately 85% of the adolescent population, and occurs most prominently at skin sites with a high density of sebaceous glands such as the face, back, and chest. Although often considered a disease of teenagers, acne is occurring at an increasingly early age. Rosacea is a chronic facial inflammatory dermatosis characterized by flushing (or transient facial erythema), persistent central facial erythema, inflammatory papules/pustules, and telangiectasia. Both acne and rosacea have a multifactorial pathology that is incompletely understood. Increased sebum production, keratinocyte hyper-proliferation, inflammation, and altered bacterial colonization with Propionibacterium acnes are considered to be the underlying disease mechanisms in acne, while the multifactorial pathology of rosacea is thought to involve both vasoactive and neurocutaneous mechanisms. Several advances have taken place in the past decade in the research field of acne and rosacea, encompassing pathogenesis and epidemiology, as well as the development of new therapeutic interventions. In this article, we provide an overview of current perspectives on the pathogenesis and treatment of acne and rosacea, including a summary of findings from recent landmark pathophysiology studies considered to have important implications for future clinical practice. The advancement of our knowledge of the different pathways and regulatory mechanisms underlying acne and rosacea is thought to lead to further advances in the therapeutic pipeline for both conditions, ultimately providing a greater array of treatments to address gaps in current management practices.
Pathogenesis and Treatment of Acne and Rosacea
An expert committee assembled by the National Rosacea Society explicitly defined and classified rosacea into four different subtypes (erythematotelangiectatic type, papulopustular, phymatous, and ocular) based on specific clinical signs and symptoms. Although didactically successful, the subtype designations were widely used individually and construed as distinct disorders, ignoring the frequent simultaneous occurrence of more than one subtype and potential progression of one subtype to another. In 2016, the global rosacea consensus panel recommended a new classification: at least one diagnostic or two major phenotypes are required for the diagnosis of rosacea. [3] Currently, the therapeutics of rosacea empirically target the signs and symptoms of the disease because investigators do not understand the details of its pathophysiology. The classification systems aide clinicians in treatment by highlighting the preponderance of one or more of the clustering signs of presentation and, thus, help to specify which therapeutic approach to initiate.
Phymatous rosacea is defined as marked skin thickenings and irregular surface nodularities of the nose, chin, forehead, one or both ears, and/or the eyelids. Four distinct histologic variants can occur with rhinophyma (associated changes of the nose) that include glandular, fibrous, fibroangiomatous, and actinic. The mainstays of treatment are isotretinoin topical application and surgical correction. This varies from other rosacea subtypes.
Spicy foods, alcohol, and hot beverages were traditionally thought to trigger flushing in patients with rosacea. However, most evidence does not support dietary factors playing a central role in the pathogenesis. Moreover, certain medications, such as amiodarone, topical steroids, nasal steroids, and high doses of vitamins B-6 and B-12, may cause flares for patients with rosacea.
Demodex species (mites that normally inhabit human hair follicles) may play a role in the pathogenesis of rosacea. Some studies suggest that Demodex prefers the skin regions that are affected in rosacea, such as the nose and cheeks. [11] Research also supports that an immune response of helper-inducer T-cell infiltrates occurs, surrounding the Demodex antigens in patients with rosacea. Yet, conflicting evidence indicates that Demodex does not induce an inflammatory response in patients with rosacea. Moreover, Demodex is found in large numbers of healthy individuals without rosacea. More studies need to be performed to determine whether Demodex truly is pathogenic.
Iron catalyzes the conversion of hydrogen peroxide to free radicals, which leads to tissue injury by damaging cellular membranes, proteins, and DNA. At the cellular level, iron that is not metabolized is stored as ferritin. In a 2009 study, skin biopsy specimens from patients with rosacea were immunohistochemically analyzed, and the number of ferritin-positive cells was significantly higher in affected individuals compared with control subjects. Additionally, higher ferritin positivity correlated with more advanced subtypes of rosacea. Thus, increased release of free iron from proteolysis of ferritin can result in oxidative damage to the skin, which may contribute to the pathogenesis of rosacea. [12]
Studies performed using video capillaroscopy on erythematotelangiectatic rosacea lesions showed increased neoangiogenesis and blood vessel enlargement. Multiple immunohistochemistry studies showed increased VEGF expression in vascular endothelium in lesional versus nonlesional skin of rosacea patients. Cuevas et al [14] used topical dobesilate, an inhibitor of angiogenic growth factor, for the treatment of erythematotelagiectatic rosacea and reported an improvement in erythema and telangiectasia after 2 weeks. [10]
AMPs are small molecular weight proteins that are a part of the innate immune response and have demonstrated broad-spectrum antimicrobial activity against bacteria, viruses, and fungi. They are rapidly released upon injury and/or infection of the skin, and they have been implicated in the pathogenesis of many inflammatory skin diseases. Cathelicidins and β-defensins are 2 well-known types of AMPs, of which the former has been shown to be expressed in abnormally high levels in patients with rosacea.
Accurate incidence data are not available; however, rosacea is a common skin condition that disproportionately affects persons of fair-skinned European and Celtic origin. In the United States, more than 16 million people are affected by rosacea, and, worldwide, as high as 18% of the population is affected. [16] A study in Sweden revealed an incidence of 1 case in 10 middle-class workers. The caseating granulomatous variant (acne agminata) may occur more commonly in people of Asian or African origin.
Oral tetracycline, doxycycline, minocycline, erythromycin, azithromycin, trimethoprim/sulfamethoxazole (TMP/SMX), trimethoprim and cephalexin have been shown to be effective in the treatment of moderate and severe acne, and forms of inflammatory acne that are resistant to topical treatments.
Increased facial sebum secretion is a common finding during the period when acne commonly develops. Patients with acne frequently think that facial sebum is the cause of their disease and want to lower or remove it completely. Sebum is always listed as one of the important factors involved in the pathogenesis of acne. Quantitative measurement of sebum has only recently become possible; currently, we have limited information on the secretion of sebum itself. The cosmetic skin type is another common method of assessing facial sebum secretion and the skin surface pH (SSPH) is partially affected by facial sebum secretion. In this chapter, sebum secretion, facial skin type, and SSPH will be reviewed with regard to their prognostic significance for acne.
N2 - Increased facial sebum secretion is a common finding during the period when acne commonly develops. Patients with acne frequently think that facial sebum is the cause of their disease and want to lower or remove it completely. Sebum is always listed as one of the important factors involved in the pathogenesis of acne. Quantitative measurement of sebum has only recently become possible; currently, we have limited information on the secretion of sebum itself. The cosmetic skin type is another common method of assessing facial sebum secretion and the skin surface pH (SSPH) is partially affected by facial sebum secretion. In this chapter, sebum secretion, facial skin type, and SSPH will be reviewed with regard to their prognostic significance for acne.
AB - Increased facial sebum secretion is a common finding during the period when acne commonly develops. Patients with acne frequently think that facial sebum is the cause of their disease and want to lower or remove it completely. Sebum is always listed as one of the important factors involved in the pathogenesis of acne. Quantitative measurement of sebum has only recently become possible; currently, we have limited information on the secretion of sebum itself. The cosmetic skin type is another common method of assessing facial sebum secretion and the skin surface pH (SSPH) is partially affected by facial sebum secretion. In this chapter, sebum secretion, facial skin type, and SSPH will be reviewed with regard to their prognostic significance for acne.
Medications and topical irritants have also been known to trigger rosacea flares. Some acne and wrinkle treatments reported to cause rosacea include microdermabrasion and chemical peels, as well as high dosages of isotretinoin, benzoyl peroxide, and tretinoin.
Small intestinal bacterial overgrowth (SIBO) was demonstrated to have greater prevalence in rosacea patients and treating it with locally acting antibiotics led to rosacea lesion improvement in two studies. Conversely in rosacea patients who were SIBO negative, antibiotic therapy had no effect.[17] The effectiveness of treating SIBO in rosacea patients may suggest that gut bacteria play a role in the pathogenesis of rosacea lesions.
Most people with rosacea have only mild redness and are never formally diagnosed or treated. No test for rosacea is known. In many cases, simple visual inspection by a trained health-care professional is sufficient for diagnosis. In other cases, particularly when pimples or redness on less-common parts of the face is present, a trial of common treatments is useful for confirming a suspected diagnosis. The disorder can be confused or co-exist with acne vulgaris or seborrheic dermatitis. The presence of a rash on the scalp or ears suggests a different or co-existing diagnosis because rosacea is primarily a facial diagnosis, although it may occasionally appear in these other areas. 041b061a72