Zileuton, an Oral 5-Lipoxygenase Inhibitor, Directly Reduces Sebum Production

Strategies of targeting CYP51 for IFIs therapy: Emerging prospects, opportunities and challenges

CYP51, a monooxygenase associated with the sterol synthesis pathway, is responsible for the catalysis of the 14-methyl hydroxylation reaction of lanosterol precursors. This enzyme is widely present in microorganisms, plants, and mammals. In mammals, CYP51 plays a role in cholesterol production, oligodendrocyte formation, oocyte maturation, and spermatogenesis. In fungal cells, CYP51 is an enzyme that synthesizes membrane sterols. By inhibiting fungal CYP51, ergosterol synthesis can be inhibited and ergosterol membrane fluidity is altered, resulting in fungal cell apoptosis. Thus, targeting CYP51 is a reliable antifungal strategy with important implications for the treatment of invasive fungal infections (IFIs). Many CYP51 inhibitors have been approved by the FDA for clinical treatment. However, several limitations of CYP51 inhibitors remain to be resolved, including fungal resistance, hepatotoxicity, and drug-drug interactions. New broad-spectrum, anti-resistant, highly selective CYP51 inhibitors are expected to be developed to enhance clinical efficacy and minimize adverse effects. Herein, we summarize the structural features and biological functions of CYP51 and emphatically analyze the structure-activity relationship (SAR) and therapeutic potential of different chemical types of small-molecule CYP51 inhibitors. We also discuss the latest progress of novel strategies, providing insights into new drugs targeting CYP51 for clinical practice.

Linoleic Acid Induced Changes in SZ95 Sebocytes-Comparison with Palmitic Acid and Arachidonic Acid

Linoleic acid (LA) is an essential omega-6 polyunsaturated fatty acid (PUFA) derived from the diet. Sebocytes, whose primary role is to moisturise the skin, process free fatty acids (FFAs) to produce the lipid-rich sebum. Importantly, like other sebum components such as palmitic acid (PA), LA and its derivative arachidonic acid (AA) are known to modulate sebocyte functions. Given the different roles of PA, LA and AA in skin biology, the aim of this study was to assess the specificity of sebocytes for LA and to dissect the different roles of LA and AA in regulating sebocyte functions. Using RNA sequencing, we confirmed that gene expression changes in LA-treated sebocytes were largely distinct from those induced by PA. LA, but not AA, regulated the expression of genes related to cholesterol biosynthesis, androgen and nuclear receptor signalling, keratinisation, lipid homeostasis and differentiation. In contrast, a set of mostly down-regulated genes involved in lipid metabolism and immune functions overlapped in LA- and AA-treated sebocytes. Lipidomic analyses revealed that the changes in the lipid profile of LA-treated sebocytes were more pronounced than those of AA-treated sebocytes, suggesting that LA may serve not only as a precursor of AA but also as a potent regulator of sebaceous lipogenesis, which may not only influence the gene expression profile but also have further specific biological relevance. In conclusion, we have shown that sebocytes are able to respond selectively to different lipid stimuli and that LA-induced effects can be both AA-dependent and independent. Our findings allow for the consideration of LA application in the therapy of sebaceous gland-associated inflammatory skin diseases such as acne, where lipid modulation and selective targeting of AA metabolism are potential treatment options.

Increased Lipid Accumulation under Hypoxia in SZ95 Human Sebocytes

BACKGROUND

Excessive sebum is produced by specialized cells called sebocytes and is considered a cause or consequence of acne, sebaceous cysts, hyperplasia, and sebaceous adenoma.

OBJECTIVE

To report changes in lipid accumulation in human sebocytes under hypoxia, which occurs under conditions of seborrhea.

METHODS

Sebocytes from the immortalized human gland cell line SZ95 were cultured under conditions of hypoxia for 48 h; lipid formation was confirmed by Nile red and Oil Red O staining. To investigate whether HIF-1α plays a role in lipid accumulation, SZ95 cells transfected or treated with dimethyloxalylglycine (DMOG) were assessed by Nile red. For protein expression of the sterol regulatory element-binding protein-1 (SREBP-1) and perilipin 2 (PLIN2), Western blot analysis was performed. Differentially expressed genes (DEGs) in SZ95 sebocytes under hypoxia were revealed by RNA-Seq analyses, and the statistical significance of the correlation between hypoxic and acne/non-acne skin was evaluated using gene set enrichment analysis.

RESULTS

Hypoxia induces lipid accumulation in SZ95 sebocytes. In addition, the levels of SREBP-1 and PLIN2 were regulated by HIF-1α in SZ95 sebocytes under hypoxia. RNA-Seq analyses of DEGs in SZ95 sebocytes under hypoxia revealed 256 DEGs, including several lipid droplet-associated genes. DEGs between acne and non-acne skin are significantly enriched in hypoxia gene sets. We also detected 93 differentially expressed inflammatory mediators.

CONCLUSIONS

To the best of our knowledge, this study is the first to show that a hypoxic microenvironment can increase lipogenesis and provides a link between seborrhea and inflammation.

Anti-acne drugs in phase 1 and 2 clinical trials

INTRODUCTION

Despite the impressive increase of knowledge on acne etiology accumulated during the last 20 years, few efforts have been overtaken to introduce new therapeutic regiments targeting the ideal treatment of acne. The increasing emergence of microbial resistance associated with antibiotics, teratogenicity, particularly associated with systemic isotretinoin, and the need for an adverse drug profile, which can be tolerated by the patient, make the need of new pathogenesis relevant anti-acne agents an emerging issue. Areas covered: A search for phase 1 and 2 acne treatment trials in the US National Institutes of Health database of clinical trials and the European Medicines Agency database with the key words 'acne' and 'treatment' was carried out, on 6 January 2017. Expert opinion: The detected trials mostly investigate topical agents that may act via sebosuppressive effects, antimicrobial properties or anti-inflammatory actions. The compounds under investigation include olumacostat glasaretil, cortexolone 17α-propionate, stearoyl-CoA desaturase 1 inhibitors, agents affecting the melanocortin system, omiganan, and minocycline. Systemic studied anti-acne drugs include finasteride, biologics, low dose anti-inflammatory antibiotics, and leukotriene B4 inhibitors.

Management of severe acne

Acne is the most common skin disease, affecting up to 95% of adolescents. Severe episodes of acne can cause considerable physical and psychological scarring, and overexpression of transforming growth factor-β can lead to formation of hypertrophic scars and keloids. The severity of acne in adolescence is associated with a positive history of severe acne in first-degree relatives, especially the mother. In most cases acne is a chronic disease, and it is often a component of systemic diseases or syndromes. All forms of severe acne require systemic treatment. The available options include oral antibiotics, hormonal antiandrogens for female patients and oral isotretinoin, as well as other combination treatments. Oral isotretinoin is the only drug available that affects all four pathogenic factors of acne. However, due to possible serious side-effects, a European directive states that oral isotretinoin should be used only as a second-line therapy in cases of severe, nodular and conglobate acne. The pharmaceutical quality of generic isotretinoin products and the obtainability of isotretinoin through e-pharmacies without prescription raise new therapeutic problems. New anti-inflammatory compounds, such as the 5-lipoxygenase inhibitor zileuton, may replace systemic antibiotics in the future, especially under the scope of antibiotic resistance prevention. This review looks into the various options and latest approaches, and factors to consider, when combating severe acne.

Acne vulgaris

Acne vulgaris is a chronic inflammatory disease - rather than a natural part of the life cycle as colloquially viewed - of the pilosebaceous unit (comprising the hair follicle, hair shaft and sebaceous gland) and is among the most common dermatological conditions worldwide. Some of the key mechanisms involved in the development of acne include disturbed sebaceous gland activity associated with hyperseborrhoea (that is, increased sebum production) and alterations in sebum fatty acid composition, dysregulation of the hormone microenvironment, interaction with neuropeptides, follicular hyperkeratinization, induction of inflammation and dysfunction of the innate and adaptive immunity. Grading of acne involves lesion counting and photographic methods. However, there is a lack of consensus on the exact grading criteria, which hampers the conduction and comparison of randomized controlled clinical trials evaluating treatments. Prevention of acne relies on the successful management of modifiable risk factors, such as underlying systemic diseases and lifestyle factors. Several treatments are available, but guidelines suffer from a lack of data to make evidence-based recommendations. In addition, the complex combination treatment regimens required to target different aspects of acne pathophysiology lead to poor adherence, which undermines treatment success. Acne commonly causes scarring and reduces the quality of life of patients. New treatment options with a shift towards targeting the early processes involved in acne development instead of suppressing the effects of end products will enhance our ability to improve the outcomes for patients with acne.

Discovery of a novel dual fungal CYP51/human 5-lipoxygenase inhibitor: implications for anti-fungal therapy

We report the discovery of a novel dual inhibitor targeting fungal sterol 14α-demethylase (CYP51 or Erg11) and human 5-lipoxygenase (5-LOX) with improved potency against 5-LOX due to its reduction of the iron center by its phenylenediamine core. A series of potent 5-LOX inhibitors containing a phenylenediamine core, were synthesized that exhibit nanomolar potency and >30-fold selectivity against the LOX paralogs, platelet-type 12-human lipoxygenase, reticulocyte 15-human lipoxygenase type-1, and epithelial 15-human lipoxygenase type-2, and >100-fold selectivity against ovine cyclooxygenase-1 and human cyclooxygnease-2. The phenylenediamine core was then translated into the structure of ketoconazole, a highly effective anti-fungal medication for seborrheic dermatitis, to generate a novel compound, ketaminazole. Ketaminazole was found to be a potent dual inhibitor against human 5-LOX (IC₅₀ = 700 nM) and CYP51 (IC₅₀ = 43 nM) in vitro. It was tested in whole blood and found to down-regulate LTB4 synthesis, displaying 45% inhibition at 10 µM. In addition, ketaminazole selectively inhibited yeast CYP51 relative to human CYP51 by 17-fold, which is greater selectivity than that of ketoconazole and could confer a therapeutic advantage. This novel dual anti-fungal/anti-inflammatory inhibitor could potentially have therapeutic uses against fungal infections that have an anti-inflammatory component.

Potential role of FoxO1 and mTORC1 in the pathogenesis of Western diet-induced acne

Acne in adolescents of developed countries is an epidemic skin disease and has currently been linked to the Western diet (WD). It is the intention of this viewpoint to discuss the possible impact of WD-mediated nutrient signalling in the pathogenesis of acne. High glycaemic load and dairy protein consumption both increase insulin/insulin-like growth factor-1 (IGF-1) signalling (IIS) that is superimposed on elevated IGF-1 signalling of puberty. The cell's nutritional status is primarily sensed by the forkhead box transcription factor O1 (FoxO1) and the serine/threonine kinase mammalian target of rapamycin complex 1 (mTORC1). Increased IIS extrudes FoxO1 into the cytoplasm, whereas nuclear FoxO1 suppresses hepatic IGF-1 synthesis and thus impairs somatic growth. FoxO1 attenuates androgen signalling, interacts with regulatory proteins important for sebaceous lipogenesis, regulates the activity of innate and adaptive immunity, antagonizes oxidative stress and most importantly functions as a rheostat of mTORC1, the master regulator of cell growth, proliferation and metabolic homoeostasis. Thus, FoxO1 links nutrient availability to mTORC1-driven processes: increased protein and lipid synthesis, cell proliferation, cell differentiation including hyperproliferation of acroinfundibular keratinocytes, sebaceous gland hyperplasia, increased sebaceous lipogenesis, insulin resistance and increased body mass index. Enhanced androgen, TNF-α and IGF-1 signalling due to genetic polymorphisms promoting the risk of acne all converge in mTORC1 activation, which is further enhanced by nutrient signalling of WD. Deeper insights into the molecular interplay of FoxO1/mTORC1-mediated nutrient signalling are thus of critical importance to understand the impact of WD on the promotion of epidemic acne and more serious mTORC1-driven diseases of civilization.

Sebaceous hyperplasia: a pilot study to correlate this skin disease with circulating androgen levels

BACKGROUND

The sebaceous glands are susceptible to the effects of androgens. A benign proliferation of these hormones, i.e. hyperplasia, occurs with age.

OBJECTIVES

This was a pilot study to demonstrate whether any correlation exists between circulating androgen levels and an increase in the incidence of sebaceous hyperplasia.

METHODS

Sixteen female patients with a diagnosis of sebaceous hyperplasia were compared to a control group of females of a similar age without the disease. Blood tests were performed on participants of both groups to measure circulating androgen levels (free and total testosterone and androstenedione levels). Results were tabulated for statistical analysis.

RESULTS

These data showed no statistically significant differences in circulating androgen levels between the patients with sebaceous hyperplasia and the control group.

CONCLUSION

These data suggest that no significant changes occur in circulating androgen levels [free and total testosterone, androstenedione, dehydroepiandrosterone (DHEA) and DHEA sulfate] in patients with sebaceous hyperplasia.

Protein kinase C isoforms have differential roles in the regulation of human sebocyte biology

Protein kinase C (PKC) isoforms have crucial roles in cutaneous signaling. Interestingly, we lack information about their involvement in human sebaceous gland biology. Therefore, in this current study, we investigated the functions of the PKC system in human immortalized SZ95 sebocytes. Using molecular biological approaches, imaging, and functional assays, we report that SZ95 sebocytes express the conventional cPKCα; the novel nPKCδ, ɛ, and η; and the atypical aPKCζ. Activation of the PKC system by phorbol 12-myristate 13-acetate (PMA) stimulated lipid synthesis (a hallmark of differentiation) and resulted in translocation and then downregulation of cPKCα and nPKCδ. In good accord with these findings, the effect of PMA was effectively abrogated by inhibitors and short interfering RNA-mediated "silencing" of cPKCα and nPKCδ. Of further importance, molecular or pharmacological inhibition of nPKCδ also prevented the lipogenic and apoptosis-promoting action of arachidonic acid. Finally, we also found that "knockdown" of the endogenous aPKCζ activity markedly increased basal lipid synthesis and apoptosis, suggesting its constitutive activity in suppressing these processes. Collectively, our findings strongly argue for the fact that certain PKCs have pivotal, isoform-specific, differential, and antagonistic roles in the regulation of human sebaceous gland-derived sebocyte biology.

Zileuton, a new efficient and safe systemic anti-acne drug

Tissue inflammation is a major component of the acne process. Leukotriene B(4) (LTB(4)) is considered to be a major player in the development of tissue inflammation. Synthesis of LTB(4) is controlled by the enzyme 5-lipoxygenase. Since Zileuton blocks the activity of 5-lipoxygenase, experimental and clinical studies have been conducted to test mode of function, as well as efficacy and safety of this compound in the treatment of acne vulgaris. Human SZ95 sebocytes and inflammatory cells in vitro express the enzymes of the leukotriene pathway at mRNA and protein levels and enzymes involved in the biosynthesis of LTB(4) are activated in sebaceous glands of acne lesions. Pre-treatment of SZ95 sebocytes with Zileuton partially prevented short-term arachidonic acid-induced effects, such as induction of LTB(4), increase of neutral lipid content and stimulation of interlekin-6 release. Long-term treatment with Zileuton directly reduced the content of neutral lipids and interleukin-6 release from SZ95 seb ocytes. PPAR mRNA levels were not regulated by Zileuton. In a first pilot clinical study with 10 patients with papulopustular acne Zileuton 4 x 600 mg/d p.o. for 3 months decreased the acne severity index in a time-dependent manner being 41% of the initial score at week 12 (p < 0.05). This was mostly due to a decrease of the number of inflammatory lesions of 29% (p < 0.01). In addition, total sebum lipids significantly decreased (35%, p < 0.05) and the pro-inflammatory free fatty acids (22%) and lipoperoxides (26%) were markedly diminished in patients' sebum under treatment. The magnitude of clinical improvement strongly correlated with the reduction of total sebum lipids (p = 0.0009, r(2) = 0.81) and free fatty acids (p = 0.0003, r(2) = 0.82). In a further study, a 40-year-old female with mild disseminated sebaceous gland hyperplasia and seborrhea, responded with normalization of the casual skin surface lipids and similar reduction of facial sebum synthesis under treatment with Zileuton over 2weeks and-after a wash-out phase-low-dose isotretinoin (10 mg/2nd d) over 5 weeks. These data are in agreement with a phase II multicenter, clinical study in 101 patients with mild to moderate inflammatory facial acne conducted in the US, which showed a significant efficacy of Zileuton in a subset of patients with moderate acne, whereas those patients treated with Zileuton showed a significant mean decrease in inflammatory lesions compared to the placebo group. In all clinical studies, Zileuton was found to be safe and well tolerated.

Peroxisome proliferator-activated receptors (PPARs) in dermatology: Challenge and promise

Since their discovery it has become clear that peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors involved in the genetic regulation of the lipid metabolism and energy homoeostasis. Subsequently, accumulating evidence suggests a role of PPARs in genomic pathways including the regulation of cell growth, apoptosis and differentiation. These findings indicate that PPARs and PPAR agonists play an important role in inflammatory responses and tumor promotion. Because of their diverse biologic activities on keratinocytes and other skin cells, PPARs represent a major research target for the understanding and treatment of many skin pathologies, such as hyperproliferative and inflammatory diseases. Overmore recent clinical trials identified PPARs as promising drug targets for the prevention and treatment of various diseases in the field of dermatology. The present review summarizes the current knowledge of PPAR functions in various skin disorders particularly those involving inflammation and epidermal hyperproliferation (i.e., psoriasis, atopic dermatitis, acne, scleroderma, skin malignancies).

Regulation of stearoyl-coenzyme A desaturase and fatty acid delta-6 desaturase-2 expression by linoleic acid and arachidonic acid in human sebocytes leads to enhancement of proinflammatory activity but does not affect lipogenesis

BACKGROUND

Treatment of SZ95 sebocytes with the essential fatty acid linoleic acid (LA) and the polyunsaturated fatty acid arachidonic acid (AA) leads to sebaceous lipogenesis. Animal data indicate that stearoyl-coenzyme A desaturase (SCD), a key enzyme in fatty acid biosynthesis, is involved in sebaceous lipogenesis and proinflammatory signalling in the sebaceous gland. On the other hand, fatty acid delta-6 desaturase-2 (FADS2) catalyses the conversion of LA to AA.

OBJECTIVES

To identify the effects of LA and AA on the expression of SCD and FADS2 and to detect its biological relevance.

METHODS

SZ95 sebocytes were treated with LA (10(-5) and 10(-4) mol L(-1) ), AA (10(-6) and 10(-5) mol L(-1) ) and the combination of LA (10(-4) mol L(-1) ) and testosterone (2 × 10(-8) mol L(-1) ), with or without addition of the SCD inhibitor FPCA (10(-8) and 10(-6) mol L(-1) ). Cytotoxicity was determined by the lactate dehydrogenase assay. SCD and FACS2 mRNA levels were assessed by semiquantitative reverse transcription-polymerase chain reaction and protein expression by Western blot analysis. SZ95 sebocyte lipid content and cell number were measured by the Nile red and the fluorescein diacetate microassays, respectively. Determination of interleukin (IL)-6 and IL-8 release was evaluated by enzyme-linked immunosorbent assay.

RESULTS

LA treatment induced an increase of SCD and FADS2 at mRNA and protein levels in SZ95 sebocytes after 1·5 h. Treatment with AA led to an increase of SCD but to a decrease of FADS2 mRNA levels. LA/testosterone cotreatment stimulated lipogenesis in SZ95 sebocytes. A distinct proinflammatory pattern was registered: whereas LA strongly upregulated IL-6 secretion only, AA induced a mild level of IL-6 and IL-8 release from SZ95 sebocytes. Treatment with the SCD inhibitor FPCA reduced the LA/testosterone-upregulated SCD and FADS2 mRNA levels and resulted in an anti-inflammatory effect, but did not affect sebaceous lipogenesis.

CONCLUSIONS

LA-induced sebaceous lipogenesis is likely to be an SCD-independent effect. Regulation of SCD and FADS2 expression by LA and AA leads to enhancement of proinflammatory activity but does not affect lipogenesis in human sebocytes.

Treating acne with antibiotic-resistant bacterial colonization

INTRODUCTION

Acne is a chronic skin disorder of the pilosebaceous unit; it has a multifactorial pathogenesis. Propionibacterium acnes within the follicle is considered to be a triggering factor of inflammation in acne. Antibiotics have been the primary treatment against P. acnes for more than 40 years. However, a gradual increase in the prevalence of antibiotic-resistant strains of P. acnes has been observed.

AREAS COVERED

This review discusses the pathophysiology of antibiotic-resistant acne development. It focuses on strategies to minimize the development of resistance and, most importantly, confront the development of antibiotic-resistant acne. The literature search was conducted up to August 2010, using the search terms 'acne', 'antibiotic-resistant acne' and 'bacterial resistance'.

EXPERT OPINION

Antibiotic-resistant acne is a real phenomenon. Strategies to prevent and confront it should include not only the use of certain treatment regimens but also rational prescribing policies, combination therapies, use of antibacterial non-antibiotic agents and treatment options targeting all the pathogenetic components of acne. Benzoyl-peroxide-based treatment is the most evidence-based approach. Oral isotretinoin remains the most efficacious option for severe acne.

Lipid mediators in acne

Multiple factors are involved in acne pathogenesis, and sebum secretion is one of the main ones. The role sebum plays in acne development has not been completely elucidated yet; however, increasing amounts of data seem to confirm the presence of alterations in sebum from acne patients. Altered ratio between saturated and unsaturated fatty acids has been indicated as an important feature to be considered in addition to the altered amount of specific fatty acids such as linoleic acid. Furthermore, particular attention has been focused on squalene peroxide that seems to be able to induce an inflammatory response beyond cytotoxicity and comedones formation. Moreover, recent data suggest that lipid mediators are able to interfere with sebocytes differentiation and sebogenesis through the activation of pathways related to peroxisome proliferators-activated receptors. Understanding the factors and mechanisms that regulate sebum production is needed in order to identify novel therapeutic strategies for acne treatment.

FoxO1 - the key for the pathogenesis and therapy of acne?

Five main factors play a pivotal role in the pathogenesis of acne: androgen dependence, follicular retention hyperkeratosis, increased sebaceous lipogenesis, increased colonization with P. acnes, and inflammatory events. This paper offers a solution for the pathogenesis of acne and explains all major pathogenic factors at the genomic level by a relative deficiency of the nuclear transcription factor FoxO1. Nuclear FoxO1 suppresses androgen receptor, other important nuclear receptors and key genes of cell proliferation, lipid biosynthesis and inflammatory cytokines. Elevated growth factors during puberty and persistent growth factor signals due to Western life style stimulate the export of FoxO1 out of the nucleus into the cytoplasm via activation of the phos-phoinositide-3-kinase (PI3K)/Akt pathway. By this mechanism, genes and nuclear receptors involved in acne are derepressed leading to increased androgen receptor-mediated signal transduction, increased cell proliferation of androgen-dependent cells, induction of sebaceous lipogenesis and upregulation of Toll-like-receptor-2-dependent inflammatory cytokines. All known acne-inducing factors exert their action by reduction of nuclear FoxO1 levels. In contrast, retinoids, antibiotics and dietary intervention will increase the nuclear content of FoxO1, thereby normalizing increased transcription of genes involved in acne. Various receptor-mediated growth factor signals are integrated at the level of PI3K/Akt activation which finally results in nuclear FoxO1 deficiency.

[Acne vulgaris. The role of hormones]

Peripherally active androgens control cellular functions by binding to androgen receptors. Follicular keratinocytes and sebocytes are target cells for androgens, which, directly or indirectly, stimulate keratinocyte proliferation and the volume of sebaceous glands as well as the sebum secretion rate. Acne often begins with the adrenarche, namely with the up- regulation of adrenal synthesis of dehydroepiandrosterone sulfate, a hormone that is upstream to testosterone. The majority of acne patients exhibit normal levels of circulating androgens, while sebaceous glands from acne regions exhibit a stronger sensitivity to androgens than the sebaceous glands from other parts of the body. Hormone-like active lipids, hormones in diet and neuropeptides may also play a role in the development of acne lesions. The target of antiandrogen treatment of the skin is mainly the sebaceous gland and the primary effect is sebostasis.

Zileuton prevents the activation of the leukotriene pathway and reduces sebaceous lipogenesis

Arachidonic acid (AA) activates the 5-lipoxygenase, induces leukotriene-B(4) (LTB(4)) synthesis, enhances interleukin-6 (IL-6) release and increases intracellular neutral lipids in human sebocytes. Moreover, the enzymes of LTB(4) biosynthesis are activated in acne-involved sebaceous glands. Zileuton a 5-lipoxygenase inhibitor, reduces the number of inflammatory acne lesions and lipogenesis in patients with acne. In this study, we investigated the activity of zileuton on LTB(4) generation, lipid content and IL-6 and -8 release from human SZ95 sebocytes in vitro. Pretreatment with zileuton partially prevented the AA-induced LTB(4) and IL-6 release and increased neutral lipid content. IL-6 release and neutral lipid content were also reduced under long-term zileuton treatment. In conclusion, zileuton prevents the activation of the leukotriene pathway and enhancement of lipogenesis by AA in human sebocytes in vitro.

New insights into the management of acne: an update from the Global Alliance to Improve Outcomes in Acne group

The Global Alliance to Improve Outcomes in Acne published recommendations for the management of acne as a supplement to the Journal of the American Academy of Dermatology in 2003. The recommendations incorporated evidence-based strategies when possible and the collective clinical experience of the group when evidence was lacking. This update reviews new information about acne pathophysiology and treatment-such as lasers and light therapy-and relevant topics where published data were sparse in 2003 but are now available including combination therapy, revision of acne scarring, and maintenance therapy. The update also includes a new way of looking at acne as a chronic disease, a discussion of the changing role of antibiotics in acne management as a result of concerns about microbial resistance, and factors that affect adherence to acne treatments. Summary statements and recommendations are provided throughout the update along with an indication of the level of evidence that currently supports each finding. As in the original supplement, the authors have based recommendations on published evidence as much as possible.

Acne vulgaris, mental health and omega-3 fatty acids: a report of cases

Acne vulgaris is a common skin condition, one that is associated with significant psychological disability. The psychological impairments in acne include higher rates of depression, anxiety, anger and suicidal thoughts. Despite a paucity of clinical research, patients with skin conditions and/or mental health disorders are frequent consumers of dietary supplements. An overlap may exist between nutrients that potentially have both anti-acne and mood regulating properties; examples include omega-3 fatty acids from fish oil, chromium, zinc and selenium. Here we report on five cases of acne treated with eicosapentaenoic acid and antioxidant nutrients. Self-administration of these nutrients may have improved inflammatory acne lesions and global aspects of well-being; the observations suggest a need for controlled trials.

Receptors of Eccrine, Apocrine, and Holocrine Skin Glands

Skin glands are highly active miniorgans of skin that fulfill a diversity of functions. To coordinate metabolic and secretory activity, they express specific receptors. Recent investigations reveal expression of nuclear hormone receptors, neuropeptide receptors, cytokine receptors, and receptors for peptides of the transforming growth factor superfamily. There is evidence of not only central control, but also autocrine mechanisms of skin glands activity. The knowledge of ligand receptor interactions in these specialized skin structures might offer not only a better understanding of their pathology, but also new therapeutic options.

Acne vulgaris: nutritional factors may be influencing psychological sequelae

Acne vulgaris is a distressing skin condition which can carry with it significant psychological disability. Patients with acne are more likely to experience anger and are at increased risk of depression, anxiety, suicidal ideation. Certain nutrients which have been implicated as influencing the pathophysiology of acne have also been identified as important mediators of human cognition, behavior and emotions. Zinc, folic acid, selenium, chromium and omega-3 fatty acids are all examples of nutrients which have been shown to influence depression, anger and/or anxiety. These same nutrients, along with systemic oxidative stress and an altered intestinal microflora have been implicated in acne vulgaris. It is our contention that certain nutritional factors, a weakened antioxidant defense system and altered intestinal microflora may interplay to increase the risk of psychological sequelae in acne vulgaris.

Abuse of anabolic-androgenic steroids and bodybuilding acne: an underestimated health problem

Abuse of anabolic-androgenic steroids (AAS) by members of fitness centers and others in Germany has reached alarming dimensions. The health care system provides the illegal AAS to 48.1 % of abusers. Physicians are involved in illegal prescription of AAS and monitoring of 32.1 % of AAS abusers. Besides health-threatening cardiovascular, hepatotoxic and psychiatric long-term side effects of AAS, acne occurs in about 50 % of AAS abusers and is an important clinical indicator of AAS abuse, especially in young men 18-26 years of age. Both acne conglobata and acne fulminans can be induced by AAS abuse. The dermatologist should recognize bodybuilding acne, address the AAS abuse, and warn the patient about other potential hazards.

Peroxidated Squalene Induces the Production of Inflammatory Mediators in HaCaT Keratinocytes: A Possible Role in Acne Vulgaris

In order to investigate whether products derived from the oxidation of sebum can be responsible for the induction of inflammatory processes, HaCaT keratinocytes were treated with peroxidated squalene. NF-kappaB activation, secretion, and expression of IL-6, as well as peroxisome proliferator-activated receptor alpha (PPARalpha) mRNA and protein levels, were measured at the end of the treatment and after 24 and 48 hours of recovery. Squalene peroxidation products were administered in amounts able to elicit significant hyperproliferation and to induce lipoxygenase (LOX) activity. The results showed an early activation of NF-kappaB followed by an increase in PPARalpha mRNA and protein levels. Moreover, squalene peroxides induced an initial upregulation of IL-6 production and secretion that was counteracted by PPARalpha activation, as suggested by the subsequent decrease of NF-kappaB nuclear translocation and IL-6 levels. Inflammatory processes play an important role in the development of acne vulgaris. In combination with our own previous findings, which indicated an association between LOX stimulation and increased percentage of proinflammatory lipids in acne as well as a correlation between increased cytokine levels in the infundibulum, pilosebaceous duct hyperkeratinization, and augmented sebogenesis, the present data further support the involvement of lipid peroxides, in particular squalene peroxides, in establishing an inflammatory process in acne.

Peroxisome Proliferator-Activated Receptors Increase Human Sebum Production

Sebum production is key in the pathophysiology of acne, an extremely common condition, which when severe, may require treatment with isotretinoin, a known teratogen. Apart from isotretinoin and hormonal therapy, no agents are available to reduce sebum. Increasing our understanding of the regulation of sebum production is a milestone in identifying alternative therapeutic targets. Studies in sebocytes and human sebaceous glands indicate that agonists of peroxisome proliferator-activated receptors (PPARs) alter sebaceous lipid production. The goal of this study is to verify the expression and activity of PPARs in human skin and SEB-1 sebocytes and to assess the effects of PPAR ligands on sebum production in patients. To investigate the contribution of each receptor subtype to sebum production, lipogenesis assays were performed in SEB-1 sebocytes that were treated with PPAR ligands and isotretinoin. Isotretinoin significantly decreased lipogenesis, while the PPARalpha agonist-GW7647, PPARdelta agonist-GW0742, PPARalpha/delta agonist-GW2433, PPARgamma agonist rosiglitazone, and the pan-agonist-GW4148, increased lipogenesis. Patients treated with thiazolidinediones or fibrates had significant increases in sebum production (37 and 77%, respectively) when compared to age-, disease-, and sex-matched controls. These data indicate that PPARs play a role in regulating sebum production and that selective modulation of their activity may represent a novel therapeutic strategy for the treatment of acne.

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 A(4) hydrolase were expressed at mRNA and protein levels in vivo and in SZ95 sebocytes in vitro (leukotriene A(4) 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 B(4) and interleukin 6 release as well as prostaglandin E(2) biosynthesis in SZ95 sebocytes, induced abundant increase in neutral lipids and down-regulated peroxisome proliferator-activated receptor-alpha, but not receptor-gamma1 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.

Pathophysiologie der Akne

Several pathogenic factors contribute to the development of acne, among them, seborrhea, follicular hyperkeratosis, propionibacteria, and inflammatory events. This article reviews current knowledge of these pathogenic factors.