The Pro-Differentiation Effect of Doxycycline on Human SZ95 Sebocytes.

BACKGROUND: Despite their widespread clinical use in both acne vulgaris and rosacea, the effects of tetracyclines on sebocytes have not been investigated until now. Sebaceous glands are central to the pathogenesis of acne and may be important in the development of rosacea. OBJECTIVE: The aim of this study was to assess the effects of doxycycline on the immortalized SZ95 sebaceous gland cell line as a model for understanding possible effectiveness on the sebaceous glands in vivo. METHODS: The effects of doxycycline on SZ95 sebocyte numbers, viability, and lipid content as well as its effects on the mRNA levels of peroxisome proliferator-activated receptors α and γ, in comparison to the peroxisome proliferator-activated receptor γ agonist troglitazone, were investigated. RESULTS: Doxycycline reduced the cell number and increased the lipid content of SZ95 sebocytes in vitro after 2 days of treatment. These doxycycline effects may be explained by an upregulation of peroxisome proliferator-activated receptor γ mRNA levels at 12 and 24 h, whereas troglitazone already upregulated peroxisome proliferator-activated receptor γ levels after 6 h. Both compounds did not influence peroxisome proliferator-activated receptor α mRNA levels. CONCLUSION: These new findings illustrate a previously unknown effect of doxycycline on sebocytes, which may be relevant to their modulation of disorders of the pilosebaceous unit, such as acne vulgaris and rosacea.

Demodex and rosacea revisited.

Demodex mites are part of the vast microbiome living on and within human skin. The interaction of the various microorganisms with the skin plays a key role in the maintenance of homeostasis. The precise role and function of Demodex mites within normal and diseased human skin remains elusive. The emergence of ivermectin as a key therapy for rosacea has refocused interest in the role of Demodex mites in the pathogenesis of this skin disease and the ability of Demodex to modulate the host immune system.

Papulopustular rosacea: prevalence and relationship to photodamage.

BACKGROUND: The prevalence and pathogenesis of rosacea is uncertain. Previously, studies used varying definitions of disease and have not explored the relationship of its prevalence to ultraviolet (UV) exposure or photodamage. OBJECTIVES: We investigated the prevalence of papulopustular rosacea (PPR) and its relationship to UV radiation exposure in 1000 randomly selected Irish individuals. METHODS: A total of 1000 individuals (500 with low UV exposure and 500 with high UV exposure) were examined. PPR was diagnosed using a standardized definition and photodamage was assessed using a photodamage scale. RESULTS: The prevalence of PPR was 2.7%. PPR prevalence was not significantly related to photodamage or UV exposure. LIMITATIONS: The power to compare UV exposure among those with and without PPR was limited. CONCLUSIONS: PPR prevalence in Ireland was 2.7%. UV radiation exposure does not appear to affect the prevalence of PPR.

Infantile pyoderma gangrenosum.

Pyoderma gangrenosum (PG) is rare in infants. There have been 12 cases of PG in infants (<12 months old) reported in the past 25 years, to our knowledge. Six of these cases have been successfully controlled with systemic steroids, and one case with topical steroids alone. We report a case of an 8-month-old infant whose PG was aggressive and unresponsive to systemic steroids. Adjuvant treatment with cyclosporine was required to achieve healing. We review the previous cases of infantile PG and the therapeutic options in this age group.

Pyoderma gangrenosum: uncommon presentations.

Pyoderma gangrenosum (PG) is a rare, inflammatory, noninfective, nonneoplastic skin disorder, which is often associated with systemic diseases. These include inflammatory bowel disease, rheumatoid arthritis, paraproteinaemia, or hematologic malignancy, which can be found in up to 50% of patients with some variants of PG. Brunsting et al (Arch Dermatol 1930;22:655-80) first described PG as a disease entity in 5 patients who had painful, enlarging necrotic ulcers with bluish undermined borders surrounded by advancing zones of erythema. Four of these patients had chronic ulcerative colitis. They felt that the condition might be associated with bacterial infection (pyoderma) and considered it as linked to the underlying bowel disease. Although the cause of PG remains obscure, bacterial infection seems to be unrelated to its causation, rendering the term pyoderma redundant. In addition, the number of conditions reported in association with PG has markedly expanded in recent years, showing clearly that this is not solely a cutaneous manifestation of inflammatory bowel disease. The clinical concept of PG has also been broadened, and certain clinical variants of PG have been linked with different types of associated disease seen in these patients.

Pruritic urticarial papules and plaques of pregnancy: current status.

Pruritic urticarial papules and plaques of pregnancy is a common benign dermatosis of pregnancy that was described in 1979 as an intensely pruritic urticarial cutaneous eruption. This is a well-defined clinical entity that mainly occurs in primigravidas in the third trimester, which resolves spontaneously or with delivery and is usually responsive to topical treatments. The aetiology of PUPPP is obscure. Histology is non-specific, but consistently shows mild lymphohistiocytic perivascular inflammatory infiltrate with a variable number of eosinophils. Immunofluorescent studies are negative. The maternal and fetal prognosis are generally unaffected, and the condition is usually responsive to topical corticosteroids and oral antihistamines.

Pyoderma gangrenosum: clinicopathologic correlation and proposed diagnostic criteria.

Pyoderma gangrenosum is a rare but significant cause of ulcerations. It is a diagnosis of exclusion. Herein, we suggest diagnostic criteria and some historical perspectives on the diagnosis of pyoderma gangrenosum.

Rosacea and the pilosebaceous follicle.

The pathophysiology of rosacea remains unknown. A leading theory suggests a vascular basis; however, clinical observations and histopathologic studies suggest that inflammation of the pilosebaceous follicle may be central to the pathogenesis of rosacea. Demodex folliculorum is a frequently seen commensal in the follicles of facial skin. According to evidence from biopsies of the skin surface, individuals with rosacea have a higher density of this parasite. This increased mite density may play a role in the pathophysiology of rosacea by triggering inflammatory or specific immune reactions, mechanically blocking the follicles, or acting as a vector for bacteria. Ongoing research has shown that bacteria from patients with rosacea may behave differently at the higher skin temperature that may be present in patients with rosacea. Another group has isolated bacteria from the Demodex mites; these bacteria may play a pathogenic role in papulopustular rosacea by facilitating follicular-based inflammatory changes.

Management of pyoderma gangrenosum.

The management of pyoderma gangrenosum (PG) requires a structured approach to establishing diagnosis of the disease and assessment of the patient. Clinical management of active PG lesions should be carried out in coordination with other specialists (such as nurses and pain managers) and often necessitates a flexible, innovate attitude to therapy, because the needs of individual patients may vary widely. Although there is no single successful treatment for this disease, certain types of PG lesions are recognized to respond more readily to accepted therapies than others. We outline guidelines to the management of the patient with PG and discuss alternative therapies.