Secukinumab in adult patients with lichen planus: Efficacy and safety results from the randomised, placebo-controlled, proof-of-concept PRELUDE study.

BACKGROUND: Patients with lichen planus (LP) refractory to available therapies often experience a high disease burden; representing a population with a clear unmet need for new treatments. OBJECTIVES: To evaluate the efficacy and safety of secukinumab 300 mg over 32 weeks in adult patients with biopsy-proven cutaneous LP (CLP), mucosal LP (MLP) or lichen planopilaris (LPP), inadequately controlled by topical corticosteroids. METHODS: PRELUDE was a, randomised, double-blind, placebo-controlled, Phase 2 proof-of-concept study that enrolled patients with CLP, MLP or LPP. Eligible patients were randomised to eithersecukinumab 300 mg every 4 weeks for 32 weeks (SECQ4W), or placebo for 16 weeks followed by secukinumab 300 mg every 2 weeks (SECQ2W) for 16 weeks. The primary endpoint was achievement of the newly designed Investigator's Global Assessment (IGA) score ≤2 at Week 16. RESULTS: Overall, 111 patients were randomised (n=37 each) to CLP, MLP and LPP cohorts. As the proof-of-concept criteria were not met for any of the 3 cohorts, the primary objective was not met. A numerically higher proportion of patients achieved IGA ≤2 response at Week 16 with SECQ4W vs. placebo in the MLP (37.5% [95% credibility interval (Crl): 20.3-57.2] vs. 23.1% [95% Crl: 6.5-49.2]) and LPP cohorts (37.5% [95% Crl: 20.2-57.3] vs. 30.8% [95% Crl: 10.8-57.6]). In the LPP cohort, a sustained response for IGA ≤2 from Week 16 to Week 32 was achieved with SECQ4W (Week 16: 37.5%; Week 32: 45.8%), and a substantial improvement was observed in IGA ≤2 response in patients of this cohort switching from placebo (Week 16: 30.8%) to SECQ2W after Week 16 (Week 32: 63.6%). The safety profile was consistent with the known profile of secukinumab and showed no new or unexpected signals. CONCLUSIONS: PRELUDE is the first randomised controlled basket trial evaluating interleukin-17A inhibition with secukinumab across 3 subtypes of LP. Secukinumab was well-tolerated and safe, showing different response rates across the 3 subtypes, with numerical IGA improvements in MLP and LPP, and no response in CLP. The study raises the question of a differential role of interleukin-17A across LP subtypes. The novel IGA score showed significant correlation with patient as well as physician reported outcome measurements. TRIAL REGISTRATION NUMBER: NCT04300296.

Combination therapy for Sneddon syndrome to reduce the incidence of cerebrovascular complications.

BACKGROUND: Sneddon syndrome is an occlusive vasculopathy that presents clinically with generalized livedo racemosa on the skin and transient ischemic attacks, strokes, and cognitive or motor deficits in the central nervous system. Antiplatelet or anticoagulant therapy is recommended. Due to the limited therapeutic efficacy and the resulting serious complications, we propose combination therapy with additional infusion cycles of alprostadil and captopril and report initial long-term results. PATIENTS AND METHODS: We performed a systematic retrospective analysis of all patients with primary Sneddon syndrome who received combination therapy in our clinic between 1995 and 2020. Therapeutic outcomes were evaluated using descriptive statistics compared to historical controls receiving monotherapy. We also analyzed the event rate of complications when combination therapy was discontinued. RESULTS: During the 99.7 patient-years of follow-up, there were no transient ischemic attacks and the stroke rate dropped to 0.02 per patient-year. In comparison, the rates of transient ischemic attacks and strokes in the historical controls ranged from 0.08 to 0.035 per patient-year. After discontinuation of alprostadil therapy, eight events occurred in three patients. CONCLUSIONS: Combination therapy reduces the long-term incidence of ischemic events in patients with primary Sneddon syndrome.

Efficiency of cutaneous heat diffusion after local hyperthermia for the treatment of itch.

BACKGROUND: Today, itching is understood as an independent sensory perception, which is based on a complex etiology of a disturbed neuronal activity and leads to clinical symptoms. The primary afferents (pruriceptors) have functional overlaps with afferents of thermoregulation (thermoceptors). Thus, an antipruritic effect can be caused by antagonizing heat-sensitive receptors of the skin. The ion channel TRP-subfamily V member 1 (TRPV1) is of particular importance in this context. Repeated heat application can induce irreversible inactivation by unfolding of the protein, causing a persistent functional deficit and thus clinically and therapeutically reducing itch sensation. MATERIAL AND METHODS: To demonstrate relevant heat diffusion after local application of heat (45°C to 52°C for 3 and 5 seconds) by a technical medical device, the temperature profile for the relevant skin layer was recorded synchronously on ex vivo human skin using an infrared microscope. RESULTS: The results showed that the necessary activation temperature for TRPV1 of (≥43°C) in the upper relevant skin layers was safely reached after 3 and 5 seconds of application time. There were no indications of undesirable thermal effects. CONCLUSION: The test results show that the objectified performance of the investigated medical device can be expected to provide the necessary temperature input for the activation of heat-sensitive receptors in the skin. Clinical studies are necessary to prove therapeutic efficacy in the indication pruritus.

Permethrin Steal Effect by Unmasked Corneocytic Keratin in Topical Therapy of Scabies.

INTRODUCTION: The use of epicutaneously applied permethrin in the treatment of common scabies is considered to be the first-line therapy. Due to increasing clinical treatment failure, the development of genetic resistance to permethrin in Sarcoptes scabiei var. hominis has been postulated. In addition, metabolic resistance and pharmacokinetic limitations by parasitic digestion and reactive thickening of stratum corneum are suspected to cause a reduction in cutaneous bioavailability. METHODS: Since lipophilic permethrin is known to form hydrophobic interactions with proteins via van der Waals interactions, a similar interaction was assumed and investigated for permethrin and the protein keratin. Using keratin particles extracted from animal material, a model for hyperkeratotic and parasitic digested scabies skin was developed. Using fluorescence-labeled keratin and ³H-permethrin, their interaction potential was validated by loading and unloading experiments. Additionally, the impact of keratin to permethrin penetration was investigated based on an in vitro model using Franz diffusion cells. RESULTS: For the first time, keratin particles were introduced as a model for dyskeratotic skin, as we were able to show, the keratin particles' interaction potential with permethrin but no penetration behavior into the stratum corneum. Moreover, comparative penetration experiments of a reference formulation with and without added keratin or keratin-adherent permethrin showed that keratin causes a steal effect for permethrin, leading to a relevant reduction in cutaneous bioavailability in the target compartment. CONCLUSION: The results provide further evidence for a relevant pharmacokinetic influencing factor in the epicutaneous application of permethrin and a rationale for the necessity of keratolytic pretreatment in hyperkeratotic skin for the effective use of topical permethrin application in scabies.

Epilation and depilation in the genital area - motivation, methods, risks and recommendations from a dermatological point of view.

Pubic hair removal is a body modification practice done worldwide for different socio-cultural reasons, which is more common in women than in men, more common in younger than in older people, and more common in sexually active people than in abstinent individuals. Since there is no medical indication for genital epilation and depilation, with a few exceptions, there is only very limited evidence in the literature about the methods used and their risks. In order to provide users with guidance from a dermatological perspective on the use of different procedures and associated risks, the existing data were collected, analyzed and evaluated in a systematic literature search. For this purpose, a total of 290 articles in the English- and German-language scientific literature were identified in databases (PubMed, Google Scholar) according to defined search strategies, and 61 publications with scientific significance were identified after assessing relevance. It became clear that depilation methods (shaving, trimming, chemical depilation) are used more frequently compared to epilation methods (waxing, sugaring, mechanical epilation, electro-epilation, laser, intense pulsed light, drug epilation). The different risks and undesirable effects were analyzed in a method-associated manner and prophylactic strategies to avoid complications were developed.

Recommendations for risk minimization when using Janus kinase inhibitors for the treatment of chronic inflammatory skin diseases.

In accordance with article 20 of Regulation (EC) No 726/2004, the Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA) has re-evaluated the safety of Janus kinase inhibitors for the treatment of inflammatory diseases and formulated safety information deviating from the previous indications in the respective summary of product characteristics of the products concerned. These refer to the consideration of a possibly increased risk of venous thromboembolic or severe cardiovascular events, an increased infection rate and an increase in the prevalence of skin cancer across drugs and indications. Therefore, in patients with independent risk factors (age 65 years and older, smokers or former smokers, patients with oral contraception or hormone replacement therapy and other risk factors), it is recommended to use Janus kinase inhibitors therapeutically only if there are no suitable treatment alternatives. To facilitate a pragmatic and thorough detection of high-risk patients in everyday clinical practice, an interdisciplinary checklist was developed that is suitable as a working tool from the perspective of the dermatologist.

Influence of Janus Kinase Inhibitors on the Neuronal Activity as a Proof-of-Concept Model for Itch.

BACKGROUND: Itching is considered to be a subjective symptom of the activation of neurosensory structures by different signal molecules and trigger factors. The signaling cascades responsible for it are closely linked to inflammatory processes. This explains why itching also occurs in many inflammatory diseases. One of these signaling cascades is mediated by Janus kinases (JAKs). Recently, it could be shown on a molecular level that Janus kinase 1 (JAK1) directly activates frontal cortex neurons and thus can cause chronic itching. OBJECTIVES: This study deals with the influence of different JAK inhibitors (JAKi) on the activity of chip-based neural networks of cultured frontal cortex neurons by investigating neurophysiological activity parameters. This in vitro model provides information on dose-dependent effects of model substances with different specificity regarding the inhibition of different JAKs. METHODS: Tofacitinib (pan-JAKi), baricitinib (JAK1/2i), and upadacitinib (JAK1i) in a concentration range from 10 nmol/L to 50 µmol/L were tested in a microelectrode array neurochip culture system. RESULTS: The results show that the inhibition of the neuronal activity of frontal cortex neurons increases with JAK1 selectivity and is dependent on concentration. CONCLUSION: These observations are supported by data from clinical studies in atopic dermatitis and psoriasis. The clinical relevance of these results must be proven by further clinical studies with subjective and objective parameters for itching.

Pharmakologie der Januskinase-Inhibitoren - Teil 2: Pharmakodynamik: Pharmacology of inhibitors of Janus kinases - Part 2: Pharmacodynamics.

Als niedermolekulare Substanzen haben die Januskinase-Inhibitoren unterschiedliche, dosisabhängige pharmakologische Bindungsselektivitäten, die allerdings keine verlässlichen Aussagen über die klinische Spezifität gewünschter oder unerwünschter Wirkeffekte ermöglichen. Es ist deshalb von besonderer Bedeutung zu erkennen, dass die Pharmakodynamik der einzelnen Januskinase-Inhibitoren in Abhängigkeit der behandelten Indikation wesentlich durch die variablen Regulationsebenen des JAK/STAT-Signalwegs sowie der pharmakokinetischen Bedingungen bestimmt wird. Vor diesem Hintergrund wird deutlich, dass alleinig klinische Studiendaten in definierten Indikationen für die Bewertung der Wirksamkeit und Sicherheit von Januskinase-Inhibitoren geeignet sind. Eine unkritische Extrapolation von Beobachtungen bezüglich Wirksamkeit und Sicherheit aus Studien anderer Indikationen soll deshalb nur mit der gebotenen Zurückhaltung erfolgen.

Pharmacology of inhibitors of Janus kinases - Part 1: Pharmacokinetics.

The use of Janus kinase inhibitors for the treatment of chronic inflammatory diseases is increasingly establishing itself as a treatment option for several indications. In order to make clinical use efficient, pharmacological knowledge of the JAK/STAT signaling pathway and the special features of the pharmacokinetics of the individual drugs is essential. The JAK/STAT signaling pathway is regulated at several levels (receptor, kinase, STAT and SOCS levels), so when Janus kinase inhibitors are used, the clinically relevant pharmacodynamics are highly dependent on the dose regimen, treated indication, comedication and comorbidity. For all practical purposes, it is therefore of great importance to recognize that the factors mentioned above can have a relevant influence on the therapeutic benefit of the use of Janus kinase inhibitors. Against this background, it is particularly important to use the Janus kinase inhibitors in accordance with their approval.

Pharmacology of inhibitors of Janus kinases - Part 2: Pharmacodynamics.

As small molecules, the Janus kinase inhibitors have different, dose-dependent pharmacological binding selectivities, which, however, do not allow reliable statements about the clinical specificity of desired or side effects. It is therefore of particular importance to recognize that the pharmacodynamics of the individual Janus kinase inhibitors as a function of the treated indication is essentially determined by variable levels of regulation of the JAK/STAT signaling pathway and the pharmacokinetic conditions. Against this background, it becomes clear that only clinical trial data in defined indications are suitable for evaluating the efficacy and safety of Janus kinase inhibitors. An uncritical extrapolation of observations regarding efficacy and safety from studies of other indications should therefore only be made with due caution.

Lichen planus in Germany - epidemiology, treatment, and comorbidity. A retrospective claims data analysis.

BACKGROUND AND OBJECTIVES: Lichen planus (LP) is a chronic inflammatory skin disease and is a major burden for affected patients. However, data on this condition are scarce. This study aims to expand the knowledge on the epidemiology and treatment patterns of LP using German health claims data. PATIENTS AND METHODS: This retrospective observational study was based on the InGef research database. Prevalent and incident LP patients were identified in the years 2015 and 2018. Descriptive statistics were calculated for demographic characteristics, treatment patterns, and comorbidity. RESULTS: The prevalence of LP was 95.9 and the incidence was 20.1 per 100,000 individuals in 2018, corresponding to 79,605 prevalent LP cases in Germany. The first LP diagnosis was generally documented by a dermatologist or a primary care physician. Three-quarters of the incident and half of the prevalent patients received topical therapy, mostly without further systemic therapy. Comorbidity in LP patients was consistent with previously known associations. CONCLUSIONS: Available treatment options remain limited, underscoring the unmet need for safe and efficacious systemic treatment modalities. Lichen planus is frequently accompanied by clinically relevant systemic comorbidity. Taken together, these observations may improve our understanding of the burden of this disease and increase diagnostic awareness among clinicians.

Lichen planus in Deutschland - Epidemiologie, Behandlung und Komorbidität. Eine retrospektive Krankenkassendatenanalyse.

HINTERGRUND UND ZIELE: Lichen planus (LP) ist eine chronisch entzündliche Hauterkrankung, die eine große Belastung für die betroffenen Patienten darstellt. Es liegen jedoch nur wenige Daten zu dieser Erkrankung vor. Ziel dieser Studie ist es, das Wissen über die Epidemiologie und die Behandlungsmuster des LP anhand von Abrechnungsdaten deutscher Krankenkassen zu erweitern. PATIENTEN UND METHODEN: Diese retrospektive Beobachtungsstudie nutzte die InGef-Forschungsdatenbank. Es wurden prävalente und inzidente LP-Patienten aus den Jahren 2015 und 2018 identifiziert. Für demografische Charakteristika, Behandlungsmuster und Komorbidität wurden deskriptive Statistiken berechnet. ERGEBNISSE: Die Prävalenz des LP lag bei 95,9 und die Inzidenz bei 20,1 pro 100 000 Personen im Jahr 2018, was 79 605 prävalenten LP-Fällen in Deutschland entspricht. Die erste LP-Diagnose wurde in der Regel von einem Dermatologen oder Hausarzt gestellt. Drei Viertel der inzidenten und die Hälfte der prävalenten Patienten erhielten eine topische Therapie, meist ohne zusätzliche systemische Therapie. Die Komorbidität des LP stand im Einklang mit bereits bekannten Assoziationen. SCHLUSSFOLGERUNGEN: Die verfügbaren Therapieoptionen sind nach wie vor begrenzt, was den ungedeckten Bedarf an sicheren und wirksamen systemischen Behandlungsmodalitäten unterstreicht. Der LP ist häufig mit klinisch relevanter systemischer Komorbidität verbunden. Zusammengenommen könnten diese Beobachtungen zu einem verbesserten Verständnis der Krankheitslast führen und das diagnostische Bewusstsein für diese Erkrankung unter Klinikern schärfen.

[Development of an ivermectin-containing syrup as an extemporaneous preparation for treatment of scabies in children]. / Entwicklung eines Ivermectin-haltigen Saftes als Magistralrezeptur für Kinder zur Therapie der Skabies.

BACKGROUND: Oral ivermectin can be used to treat scabies. Evidence for safe and effective use in young children in individual treatment situations has been developed and published. In order to also ensure a body weight-adapted dosage for children, an ivermectin-containing syrup was developed as an extemporaneous preparation. MATERIALS AND METHODS: Since ivermectin is not available as a pure substance for the formulation, tablets containing active ingredient were used as a basic material for development. The formulation was designed according to pharmaceutical, regulatory and use-oriented criteria. An HPLC (high-pressure liquid chromatography) method was developed and validated to demonstrate chemical stability. In order to facilitate the practical implementation, information on suitable packaging material and application aids was also developed and the formulation was evaluated. RESULTS: It has been demonstrated that the final formulation produced in the pharmacy was stable and can be stored for 3 weeks. No concerns were raised regarding the tolerability of the syrup formulation. The physicochemical properties and the taste of the formulation allow the intended use as a well-dosed syrup for children. CONCLUSION: The developed formulation meets the requirements of the Apothekenbetriebsordnung (Pharmacy Work Rules; Section 7 ApBetrO) and enables an exact, body weight-adapted dosage of oral ivermectin in young children. Studies on human pharmacokinetics or clinical studies to demonstrate tolerability and/or efficacy are not available for the formulation.

[Recommendations when switching therapy from immunosuppressive drugs to dupilumab in patients with atopic dermatitis]. / Handlungsempfehlung zur Therapieumstellung von Immunsuppressiva auf Dupilumab bei Patienten mit atopischer Dermatitis.

Based on new insights into the molecular pathogenesis of atopic dermatitis, a targeted anti-inflammatory therapy-dupilumab-has recently been approved as treatment alongside glucocorticoids and ciclosporin. Due to their pharmacology, neither glucocorticoids nor ciclosporin nor the off label used substances methotrexate, azathioprine and mycophenolic acid derivatives are suitable for long-term therapy. When switching therapy from small molecular substances to dupilumab, various factors should be considered. Both the specific cause of the change (ineffectiveness, adverse effects or contraindications) as well as the pharmacological conditions should be taken into account. Since there have been no specific clinical studies on this subject so far, the authors relied mainly on a literature search to draw up recommendations for practical everyday use.

[Treatment of psoriasis with secukinumab : Practical guidance]. / Behandlung der Psoriasis mit Secukinumab : Praxisrelevante Hinweise.

BACKGROUND: Moderate to severe plaque psoriasis can be treated effectively with immunomodulating biologicals such as the interleukin-17A inhibitor secukinumab. In practice, however, questions often arise as to how to proceed in special situations, such as infections, comorbidity, pregnancy, or surgery. OBJECTIVES: To address frequent questions about the treatment of plaque psoriasis with secukinumab in a consensus document of German psoriasis experts that supplements current guidelines. METHODS: In a virtual expert meeting in May 2020, practical aspects of the treatment of psoriasis were discussed based on the experience of the participants and on current literature. The results of this discussion were summarized in the present consensus document. RESULTS: This article provides practical guidance on case history, documentation of previous therapies, severity of psoriasis, and comorbidities before starting therapy with secukinumab. For patients treated with secukinumab, the course of action in case of vaccinations, chronic or acute infections, surgical interventions, special manifestations of psoriasis, and comorbidities including history of cancer and autoimmune disorders is discussed. Questions regarding family planning and health policy regulations are also addressed. DISCUSSION: The recommendations for the treatment of psoriasis with secukinumab summarized in this consensus document may contribute to achieve optimal therapy for patients and to improve their quality of life.

Influence of keratolytics on cutaneous pharmacokinetics of glucocorticoids.

BACKGROUND: Keratolytics are often used to accelerate and improve the therapeutic response of hyperkeratotic dermatoses. Keratolytics are a chemically inhomogeneous group of substances and substance mixtures that clinically lead to a decrease in symptoms of a cornification disorder, but mediate different effects. Thus, keratolytic, keratoplastic, keratoemulsifying and keratodiluting effects are distinguished. The physicochemical effects or pharmacological efficacy of the respective keratolytics result in different mechanism as well as risks with regard to local or systemic compatibility. Until now, only little attention has been paid upon selection of keratolytics to the immediate consequences regarding diffusion conditions and pharmacokinetics of sequentially applied topicals, in particular of glucocorticoids. PATIENTS AND METHODS: This paper deals with the influence of keratolytics on the penetration-time profile of betamethasone dipropionate in sequential application. For this purpose, cutaneous bioavailability was investigated with the Franz chamber test using a tritium-labeled drug depending on the previous application of a keratolytic agent. Comparative data analyses were performed. RESULTS: It was shown that keratoplastic substances significantly promote diffusion of the glucocorticoid. Keratoemulsifying substance mixtures exert no relevant effects in this regard, while keratodiluting substance mixtures inhibit penetration. CONCLUSIONS: The targeted selection of a keratolytic can optimize the therapeutic effect and influence the bioavailability of sequentially applied topicals.

Importance of microRNAs in Skin Oncogenesis and Their Suitability as Agents and Targets for Topical Therapy.

Skin cancer is the most common cancer worldwide, with rapidly increasing incidence and consistent mortality. Skin cancer encompasses melanoma and non-melanoma skin cancer, which in turn is mainly divided into cutaneous squamous cell carcinoma and basal cell carcinoma. Small noncoding micro-RNAs (miRNAs) regulate protein expression after transcription and play a role in the development and progression of skin cancer. Deregulated expression of miRNAs in skin cancer is associated with cell proliferation, angiogenesis, metastasis, apoptosis, immune response, and drug resistance. Specific patterns of miRNAs in specific skin cancer types can be used as diagnostic markers. For therapeutic purposes, both miRNA and chemically modified variants thereof as well as miRNA antagonists (antagomiRs) or RNA inhibitors may be applied topically. Due to their specific physicochemical properties, physical or chemical diffusion promoters are used with varying degrees of success. There is no question by now that such preparations have a high potential for the treatment of epithelial skin tumors in particular.

Investigation of ex vivo Skin Penetration of Coenzyme Q10 from Microemulsions and Hydrophilic Cream.

INTRODUCTION: Coenzyme Q10 (CoQ10) has been widely used in topical and cosmeceutical products due to its cutaneous antioxidant and energizer effects. CoQ10 is found in a higher concentration in the epidermis compared to dermis. The epidermal level of CoQ10 can be reduced due to several factors such as skin UV irradiation and photoaging. Various dermal nano-formulations have been investigated to overcome the skin barrier and enhance the poor penetration of CoQ10. The nanocarriers are designed to target and concentrate the CoQ10 in the viable epidermis. Most of these studies, however, failed to show the depth and extent of penetration of CoQ10 from the various carrier systems. OBJECTIVE: The distribution of CoQ10 across the various skin layers has to be shown using skin slices representing the different skin layers. METHODS: To realize this objective, a sensitive and selective HPLC method was developed and validated for the quantification of CoQ10 in the different skin slices. The method applicability to skin penetration (using excised human skin) as well as stability studies was investigated using CoQ10-loaded lecithin-based microemulsion (ME) and hydrophilic cream formulations. RESULTS: It could be shown that the highest concentration of CoQ10 in the viable epidermis, the target skin layer for CoQ10, was observed after application of the CoQ10 in the hydrophilic cream. This cream contains 10% of 2-ethylhexyl laurate which works obviously as a penetration enhancer for CoQ10. In contrast, the penetration of CoQ10 was lower from the ME. Just in the deeper dermis, a certain amount of CoQ10 could be detected. CONCLUSIONS: The HPLC method quantified the trace quantities of the CoQ10 distributed across the various skin layers and, hence, can be used to investigate the skin penetration of CoQ10 from various dermal standard and nano-formulations.

Clinical Applications of Hyaluronidase.

Hyaluronidases are enzymes that degrade hyaluronic acid, which constitutes an essential part of the extracellular matrix. Initially discovered in bacteria, hyaluronidases are known to be widely distributed in nature and have been found in many classes including insects, snakes, fish and mammals. In the human, six different hyaluronidases, HYAL1-4, HYAL-P1 and PH-20, have been identified. PH-20 exerts the strongest biologic activity, is found in high concentrations in the testicles and can be localized on the head and the acrosome of human spermatozoa. Today, animal-derived bovine or ovine testicular hyaluronidases as well as synthetic hyaluronidases are clinically applied as adjuncts to increase the bioavailability of drugs, for the therapy of extravasations, or for the management of complications associated with the aesthetic injection of hyaluronic acid-based fillers. Further applications in the fields of surgery, aesthetic medicine, immunology, oncology, and many others can be expected for years to come. Here, we give an overview over the molecular and cellular mode of action of hyaluronidase and the hyaluronic acid metabolism, as well as over current and potential future clinical applications of hyaluronidase.

Quantitative Analysis of Free Amino Acids and Urea Derived from Isolated Corneocytes of Healthy Young, Healthy Aged, and Diseased Skin.

BACKGROUND/AIMS: Free amino acids (FAAs) and urea, present inside the corneocytes, can be important indicators of skin condition. However, due to the lack of a standard extraction protocol for FAAs from corneocytes, conflicting research results have been reported. Therefore, the purpose of this study was (1) to standardize the extraction protocol and (2) to investigate FAA profiles in healthy young and healthy old volunteers, as well as in psoriasis and atopic dermatitis patients. METHODS: Skin samples were collected from four groups (healthy young, healthy old, and psoriasis and atopic dermatitis patients) with 5 volunteers per group. Corneocytes were isolated and examined microscopically. FAAs and urea were extracted from the isolated corneocytes, and their amounts were quantified using LC-ESI/MS/MS (after derivatization with Fmoc-Cl) and colorimetric methods, respectively. RESULTS: The micrographs of the corneocytes showed no morphological features attributable to age or disease conditions. The highest and lowest concentrations of total FAAs and urea were observed in the healthy old group and the healthy young group, respectively. Unlike the other FAAs and urea, citrulline was found at a higher level in the healthy young group than in the disease groups. CONCLUSION: This study suggests that the levels of FAAs and urea in the skin are affected by age and skin conditions (healthy/diseased). However, further studies are needed to show the effects of different skin conditions on the levels of FAAs and urea.