Christos C. Zouboulis

New developments in our understanding of acne pathogenesis and treatment

Abstract:  Interest in sebaceous gland physiology and its diseases is rapidly increasing. We provide a summarized update of the current knowledge of the pathobiology of acne vulgaris and new treatment concepts that have emerged in the last 3 years (2005–2008). We have tried to answer questions arising from the exploration of sebaceous gland biology, hormonal factors, hyperkeratinization, role of bacteria, sebum, nutrition, cytokines and toll‐like receptors (TLRs). Sebaceous glands play an important role as active participants in the innate immunity of the skin. They produce neuropeptides, excrete antimicrobial peptides and exhibit characteristics of stem cells. Androgens affect sebocytes and infundibular keratinocytes in a complex manner influencing cellular differentiation, proliferation, lipogenesis and comedogenesis. Retention hyperkeratosis in closed comedones and inflammatory papules is attributable to a disorder of terminal keratinocyte differentiation. Propionibacterium acnes, by acting on TLR‐2, may stimulate the secretion of cytokines, such as interleukin (IL)‐6 and IL‐8 by follicular keratinocytes and IL‐8 and ‐12 in macrophages, giving rise to inflammation. Certain P. acnes species may induce an immunological reaction by stimulating the production of sebocyte and keratinocyte antimicrobial peptides, which play an important role in the innate immunity of the follicle. Qualitative changes of sebum lipids induce alteration of keratinocyte differentiation and induce IL‐1 secretion, contributing to the development of follicular hyperkeratosis. High glycemic load food and milk may induce increased tissue levels of 5α‐dihydrotestosterone. These new aspects of acne pathogenesis lead to the considerations of possible customized therapeutic regimens. Current research is expected to lead to innovative treatments in the near future.

The International Criteria for Behcet's Disease (ICBD): a collaborative study of 27 countries on the sensitivity and specificity of the new criteria

Behçets disease (BD) is a chronic, relapsing, inflammatory vascular disease with no pathognomonic test. Low sensitivity of the currently applied International Study Group (ISG) clinical diagnostic criteria led to their reassessment.

What is the pathogenesis of acne

Abstract:  For a long time, the mantra of acne pathogenesis debates has been that acne vulgaris lesions develop when (supposedly largely androgen‐mediated) increased sebum production, ductal hypercornification, and propionibacteria come together with local inflammatory process in the unlucky affected individual. And yet, the exact sequence, precise interdependence, and choreography of pathogenic events in acne, especially the ‘match that lights the fire’ have remained surprisingly unclear, despite the venerable tradition of acne research over the past century.

Current Use and Future Potential Role of Retinoids in Dermatology

SummarySince their introduction 15 years ago, retinoids have been increasingly used for topical and systemic treatment of psoriasis and other hyperkeratotic and parakeratotic skin disorders, keratotic genodermatoses, severe acne and acne-related dermatoses, and also for therapy and/or chemoprevention of skin cancer and other neoplasia. Oxidative metabolites of vitamin A (retinol) are natural retinoids present at low levels in the peripheral blood. Synthetic retinoids are classified into 3 generations including nonaromatic, monoaromatic and polyaromatic compounds. They are detectable in plasma 30–60 minutes after systemic administration, and reach maximum concentrations 2 to 4 hours later. Elimination half-life is 10 to 20 hours for isotretinoin, 80 to 175 days for etretinate and 2 to 4 days for trans-acitretin; the latter, however, partially converts into etretinate. Retinoid concentrations in skin are rather low in contrast to subcutaneous fat tissue.Intracellularly, retinoids interact with cytosolic proteins and specific nuclear receptors. Two classes of nuclear receptors have been suggested to mediate retinoid activity at the molecular level, RARs and RXRs. The expression of retinoid receptors is tissue specific; skin mainly espresses RARγ and RXRα. Retinoids affect epidermal cell growth and differentiation as well as sebaceous gland activity and exhibit immunomodulatory and anti-inflammatory properties.Current retinoid research targets the development of receptor-selective retinoids for tailoring and/or improving their therapeutic profile. Currently, tretinoin is used systemically for acute promyelocytic leukaemia, etretinate and acitretin for psoriasis and related disorders, as well as other disorders of keratinisation, and isotretinoin for seborrhoea, severe acne, rosacea and acneiform dermatoses. Systemic retinoids are also applied for chemoprevention of epithelial skin cancer and cutaneous T cell lymphoma. The major adverse effect of retinoids is teratogenicity; all other adverse effects are dose-dependent and controllable. Contraception is, therefore, essential during retinoid treatment in women of child-bearing age. Clinical monitoring requires physical examination for adverse effects every 3 to 4 weeks and proper laboratory investigations, also including analysis of retinoid bioavailability in selected cases. Topical retinoids are rapidly developing at present and seem promising for the future; their clinical application includes acne, aging, photodamage, precanceroses, skin cancer and disorders of skin pigmentation. The development of receptor-specific retinoids for topical treatment of psoriasis and/or acne may lead to interesting new compounds based on our current concepts of retinoid function.

Corticotropin-releasing hormone: An autocrine hormone that promotes lipogenesis in human sebocytes

Sebaceous glands may be involved in a pathway conceptually similar to that of the hypothalamic-pituitary-adrenal (HPA) axis. Such a pathway has been described and may occur in human skin and lately in the sebaceous glands because they express neuropeptide receptors. Corticotropin-releasing hormone (CRH) is the most proximal element of the HPA axis, and it acts as central coordinator for neuroendocrine and behavioral responses to stress. To further examine the probability of an HPA equivalent pathway, we investigated the expression of CRH, CRH-binding protein (CRH-BP), and CRH receptors (CRH-R) in SZ95 sebocytes in vitro and their regulation by CRH and several other hormones. CRH, CRH-BP, CRH-R1, and CRH-R2 were detectable in SZ95 sebocytes at the mRNA and protein levels: CRH-R1 was the predominant type (CRH-R1/CRH-R2 = 2). CRH was biologically active on human sebocytes: it induced biphasic increase in synthesis of sebaceous lipids with a maximum stimulation at 10−7 M and up-regulated mRNA levels of 3β- hydroxysteroid dehydrogenase/Δ5–4 isomerase, although it did not affect cell viability, cell proliferation, or IL-1β-induced IL-8 release. CRH, dehydroepiandrosterone, and 17β-estradiol did not modulate CRH-R expression, whereas testosterone at 10−7 M down-regulated CRH-R1 and CRH-R2 mRNA expression at 6 to 24 h, and growth hormone (GH) switched CRH-R1 mRNA expression to CRH-R2 at 24 h. Based on these findings, CRH may be an autocrine hormone for human sebocytes that exerts homeostatic lipogenic activity, whereas testosterone and growth hormone induce CRH negative feedback. The findings implicate CRH in the clinical development of acne, seborrhea, androgenetic alopecia, skin aging, xerosis, and other skin disorders associated with alterations in lipid formation of sebaceous origin.

European Evidence‐based (S3) Guidelines for the Treatment of Acne

Subcommittee Members: Dr. Alexander Nast, Berlin (Germany) Dr. Cristina Oprica, Stockholm (Sweden) Prof. Dr. Brigitte Dreno, Nantes (France) Mrs. Stefanie Rosumeck, Berlin (Germany) Dr. Vincenzo Bettoli, Ferrara (Italy) Prof. Dr. Berthold Rzany, Berlin (Germany) Prof. Dr. Klaus Degitz, Munich (Germany) Dr. Adel Sammain, Berlin (Germany) Mr. Ricardo Erdmann, Berlin (Germany) Dr. Thierry Simonart, Brussels (Belgium) Prof. Dr. Andrew Finlay, Cardiff (United Kingdom) Dr. Niels Kren Veien, Aalborg (Denmark) Prof. Dr. Ruta Ganceviciene, Vilnius (Lithuania) Dr. Maja Vurnek fivkovi , Zagreb (Croatia) Dr. Alison Layton, Harrogate (United Kingdom) Prof. Dr. Christos Zouboulis, Dessau (Germany) Dr. Jose Luis Lopez Estebaranz, Madrid (Spain) Prof. Dr. Falk Ochsendorf, Frankfurt (Germany) Prof. Dr. med. Harald Gollnick, Magdeburg (Germany)

Adalimumab for the Treatment of Moderate to Severe Hidradenitis Suppurativa: A Parallel Randomized Trial

BACKGROUND Hidradenitis suppurativa (HS) is a chronic, painful skin disease characterized by abscesses, nodules, and draining fistulas in the axilla and groin of young adults. OBJECTIVE To evaluate the efficacy and safety of adalimumab, an anti-tumor necrosis factor-α antibody, in patients with moderate to severe HS. DESIGN Phase 2, parallel, randomized, placebo-controlled trial consisting of a blinded 16-week period (period 1) and an open-label 36-week period (period 2). All study personnel, investigators, and patients remained blinded to treatment group throughout the study. (ClinicalTrials.gov: NCT00918255) SETTING 26 academic and private practice medical centers in the United States and Europe. PATIENTS 154 adult patients with moderate to severe HS who were unresponsive or intolerant to oral antibiotics. INTERVENTION Patients were assigned in a 1:1:1 ratio to adalimumab, 40 mg/wk; adalimumab, 40 mg every other week (EOW); or placebo. All patients received adalimumab, 40 mg EOW, at the beginning of period 2 but switched to weekly dosing if the response was suboptimal (HS Physicians Global Assessment [PGA] score of moderate or worse) at weeks 28 or 31. MEASUREMENTS The primary outcome measure (clinical response) was the proportion of patients achieving an HS-PGA score of clear, minimal, or mild with at least a 2-grade improvement relative to baseline at week 16. RESULTS At week 16, 3.9% of placebo patients (2 of 51), 9.6% of EOW patients (5 of 52), and 17.6% of weekly patients (9 of 51) achieved clinical response (EOW vs. placebo strata-adjusted difference, 5.6% [95% CI, -4.0% to 15.3%]; P = 0.25; weekly vs. placebo strata-adjusted difference, 13.7% [CI, 1.7% to 25.7%]; P = 0.025). Serious adverse event rates were 3.9%, 5.8%, and 7.8% for placebo, EOW, and weekly patients, respectively (EOW vs. placebo difference, 1.8% [CI, -6.4% to 10.1%]; weekly vs. placebo difference, 3.9% [CI, -5.2% to 13.0%]). Significantly greater improvements in patient-reported outcomes and pain were seen in the weekly dosing group than in the placebo group. A decrease in response was seen after the switch from weekly to EOW dosing in period 2. LIMITATIONS Weeks 16 to 52 of the study were open-label. The study was not powered to assess the risk for known serious adverse effects of adalimumab, such as tuberculosis, other serious infections, and demyelinating disorders. CONCLUSION Adalimumab dosed once per week alleviates moderate to severe HS. PRIMARY FUNDING SOURCE Abbott Laboratories.

Prevalence, Severity, and Severity Risk Factors of Acne in High School Pupils: A Community-Based Study

A cross-sectional, community-based study was performed to determine the prevalence and severity of acne vulgaris in adolescents and of factors influencing the acne severity risk. The presence of acne was clinically determined and the secondary outcome measures of family acne history and the relation of acne to nutrition habits, emotional stress, menstruation, and smoking were recorded in a questionnaire. A representative sample of 1,002 pupils aged 16+/-0.9 years was enrolled. The overall acne prevalence was 93.3, 94.4% for boys and 92.0% for girls. Moderate to severe acne was observed in 14%. The prevalence of moderate to severe acne was 19.9% in pupils with and 9.8% in those without a family history of acne (P<0.0005; OR: 2.3). Acne severity risk increased with the number of family members with acne history. A mother with acne history influenced the severity of acne the most. Increasing pubertal age, seborrhea, the premenstrual phase, mental stress, and sweet and oily foods were recognized as risk factors for moderate to severe acne. In contrast, gender, spicy foods, and smoking were not associated with acne severity. In conclusion, acne is a common disorder in Iranian adolescents, with a low rate of moderate to severe acne. A genetic background is suggested, with mothers acne history being the most important prognostic factor. Skin quality and certain nutrition habits may affect acne severity.

Enzymes involved in the biosynthesis of leukotriene B4 and prostaglandin E2 are active in sebaceous glands.

The expression of enzymes involved in leukotriene and prostaglandin signalling pathways, of interleukins 6 and 8 and of peroxisome proliferator-activated receptors in sebaceous glands of acne-involved facial skin was compared with those of non-involved skin of acne patients and of healthy individuals. Moreover, 5-lipoxygenase and leukotriene A4 hydrolase were expressed at mRNA and protein levels in vivo and in SZ95 sebocytes in vitro (leukotriene A4 hydrolase > 5-lipoxygenase), while 15-lipoxygenase-1 was only detected in cultured sebocytes. Cyclooxygenase-1 and cyclooxygenase-2 were also present. Peroxisome proliferator-activated receptors were constitutively expressed. Enhanced 5-lipoxygenase, cyclooxygenase 2 and interleukin 6 expression was detected in acne-involved facial skin. Arachidonic acid stimulated leukotriene B4 and interleukin 6 release as well as prostaglandin E2 biosynthesis in SZ95 sebocytes, induced abundant increase in neutral lipids and down-regulated peroxisome proliferator-activated receptor-α, but not receptor-γ1 mRNA levels, which were the predominant peroxisome proliferator-activated receptor isotypes in SZ95 sebocytes. In conclusion, human sebocytes possess the enzyme machinery for functional leukotriene and prostaglandin pathways. A comprehensive link between inflammation and sebaceous lipid synthesis is provided.

A toll-like receptor 2-responsive lipid effector pathway protects mammals against skin infections with gram-positive bacteria.

ABSTRACT flake (flk), an N-ethyl-N-nitrosourea-induced recessive germ line mutation of C57BL/6 mice, impairs the clearance of skin infections by Streptococcus pyogenes and Staphylococcus aureus, gram-positive pathogens that elicit innate immune responses by activating Toll-like receptor 2 (TLR2) (K. Takeda and S. Akira, Cell. Microbiol. 5:143-153, 2003). Positional cloning and sequencing revealed that flk is a novel allele of the stearoyl coenzyme A desaturase 1 gene (Scd1). flake homozygotes show reduced sebum production and are unable to synthesize the monounsaturated fatty acids (MUFA) palmitoleate (C16:1) and oleate (C18:1), both of which are bactericidal against gram-positive (but not gram-negative) organisms in vitro. However, intradermal MUFA administration to S. aureus-infected mice partially rescues the flake phenotype, which indicates that an additional component of the sebum may be required to improve bacterial clearance. In normal mice, transcription of Scd1—a gene with numerous NF-κB elements in its promoter—is strongly and specifically induced by TLR2 signaling. Similarly, the SCD1 gene is induced by TLR2 signaling in a human sebocyte cell line. These observations reveal the existence of a regulated, lipid-based antimicrobial effector pathway in mammals and suggest new approaches to the treatment or prevention of infections with gram-positive bacteria.