Epidermal proteases in the pathogenesis of rosacea

Chronic inflammation as a proposed risk factor for ocular surface squamous neoplasia

PURPOSE

Chronic inflammation is a predisposing factor for metaplastic changes and ultimately dysplasia. We describe cases of OSSN occurring in the setting of chronic ocular surface inflammation.

METHODS

Sixteen eyes from 14 individuals were included from one ocular oncology clinic between 2010 and 2023. Patients presented with ocular surface squamous neoplasia (OSSN) in the setting of chronic inflammation. The diagnosis of OSSN was made using anterior segment high-resolution optical coherence tomography (HR-OCT) and confirmed by histopathological analysis in all cases.

RESULTS

Median age on presentation was 61 [IQR 47.5-69.2] years. Eleven (86%) individuals were male and five (36%) identified as White Hispanic. Ten eyes were referred with ocular surface diagnoses including pannus (n = 4), scarring (n = 3), pterygium (n = 2), and herpetic keratitis (n = 1). Only six eyes were referred as possible neoplasia. All individuals had a history of ocular surface inflammation. The most common inflammatory conditions were ocular rosacea (seven individuals) and atopic keratoconjunctivitis (AKC) (five individuals). Two individuals were found to have bilateral OSSN, one in the setting of ocular rosacea and the other in the setting of AKC. All 16 eyes from 14 individuals were suspected to have OSSN based on HR-OCT findings which guided the location of the incisional biopsies that subsequently confirmed histopathological diagnosis in all cases.

CONCLUSION

OSSN may arise in the setting of chronic inflammation on the ocular surface. Identification of the tumor can be challenging in these cases, and HR-OCT can be a key diagnostic tool in detecting OSSN.

Efficacy of Low-Dose Isotretinoin in the Treatment of Rosacea: A Systematic Review and Meta-Analysis

Rosacea is a common cutaneous condition caused by persistent, recurring lesions in facial skin vessels. It is a chronic skin condition with a variety of clinical symptoms and an unknown cause. Rosacea begins with the widening of capillaries and a flushed appearance. Following that, telangiectasia appears, and reddened patches persist, particularly on the cheeks and nose. Erythema persists due to repeated vasodilation and telangiectasia. In addition, skin inflammation manifests as papules, pustules, lymphedema, and fibrosis. Despite recent advances in treatment, rosacea, a chronic inflammatory relapsing central facial dermatosis, can be extremely difficult to manage.  The purpose of this meta-analysis and systematic review was to evaluate the effectiveness of low-dose isotretinoin in the treatment of rosacea. Following the guidelines set forth by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA), the researcher employed the following search terms in the EMBASE, Web of Science, PubMed, Cochrane Library, and Google Scholar databases to provide a therapeutic update relevant to clinical practice: "low dose isotretinoin," "isotretinoin and rosacea," "isotretinoin treatment of rosacea," and "effectiveness of isotretinoin in treating rosacea". The search was carried out by the researcher for articles published from February 2019 to February 2024. The articles included were all published in the English language. The overall frequency of patients with adverse events differed significantly between the groups treated with low-dose isotretinoin and the comparators (minocycline, pulsed dye laser, evening primrose oil, Lactobacillus plantarum, doxycycline, combined dose or placebo) (0.80, 95% CI 0.73 to 0.88, p = 0.0001). Sub-group analysis indicated that there was a difference between the interventions used in the treatments all in favor of low-dose isotretinoin treatment. The results showed that the moderate group had RR: 0.76, 95% CI: 0.44-1.30, I2 = 0%; the mild group had RR: 0.94, 95% CI: 0.56-1.57, I2 = 0%; and the group with severe rosacea had RR: 0.73, 95% CI: 0.47-1.13, I2 = 0%. According to this study, rosacea can be treated effectively with low-dose isotretinoin even in patients at severe stages of the disease by using the recommended dose once a week. Further, the intervention has also been shown to have fewer side effects on the patients. Therefore, this study recommends randomized controlled trials to be done to fully investigate the best combination options for isotretinoin on mild to severe rosacea based on the fact that some of the treatments combined have shown to be effective on treatment.

Rosacea: Pathogenesis and Therapeutic Correlates

Rosacea is a chronic inflammatory condition of which there is no cure. The pathogenesis of rosacea is likely multifactorial, involving genetic and environmental contributions. Current understanding suggests that pro-inflammatory pathways involving cathelicidins and inflammasome complexes are central to rosacea pathogenesis. Common rosacea triggers modulate these pathways in a complex manner, which may contribute to the varying severity and clinical presentations of rosacea. Established and emerging rosacea treatments may owe their efficacy to their ability to target different players in these pro-inflammatory pathways. Improving our molecular understanding of rosacea will guide the development of new therapies and the use of combination therapies.

Quality of life measurement in rosacea. Position statement of the European Academy of Dermatology and Venereology Task Forces on Quality of Life and Patient Oriented Outcomes and Acne, Rosacea and Hidradenitis Suppurativa

The European Academy of Dermatology and Venereology (EADV) Task Forces (TFs) on Quality of Life (QoL) and Patient-Oriented Outcomes and Acne, Rosacea and Hidradenitis Suppurativa (ARHS) do not recommend the use of any generic instrument as a single method of Health Related (HR) QoL assessment in rosacea, except when comparing quimp (quality of life impairment) in rosacea patients with that in other non-dermatologic skin diseases and/or healthy controls. The EADV TFs on QoL and Patient-Oriented Outcomes and ARHS recommend the use of the dermatology-specific HRQoL instrument the Dermatology Life Quality Index (DLQI) and the rosacea-specific HRQoL instrument RosaQoL in rosacea patients. The DLQI minimal clinically important difference may be used as a marker of clinical efficacy of the treatment and DLQI score banding of 0 or 1 corresponding to no effect on patients' HRQoL could be an important treatment goal. This information may be added to consensuses and guidelines for rosacea.

Combined therapy of 5-aminolevulinic acid photodynamic therapy and intense pulsed light for rosacea

Rosacea is difficult to treat. Therefore, new alternative modalities are necessary to demonstrate. The present study was conducted to assess the efficacy and safety of the combined therapy of 5-aminolevulinic acid photodynamic therapy (ALA-PDT) and intense pulsed light (IPL) for rosacea to provide a new treatment option for rosacea. The study was conducted from November 2017 to April 2019 at the Department of Dermatology, The First Hospital of China Medical University. Patients aged 18-65 years and diagnosed clinically as erythematotelangiectatic (ET) or papulopustular (PP) rosacea were enrolled. Three times of ALA-PDT at 10 days interval followed by 3 times of IPL at 3-4 weeks interval were defined as 1 session and applied to the whole face of each patient. ALA-PDT: 5% ALA, red light (fluency dose 60-100 mW/cm2, 20 min); IPL: 560/590/640 nm, double/triple-pulse mode, pulse width 3.0 to 4.5 ms, delay time 30-40 ms, energy fluency 14-17 J/cm2. Ten patients were enrolled in the study. Among them, 4 patients received only 1 session, while 6 patients received 2 sessions. After all treatments, 50% of patients achieved 75-100% improvement, and 30% achieved 50-75% improvement. Forty percent of patients were graded very satisfaction and 30% graded moderate satisfaction. All noninvasive measurements showed no significant differences among all time points (p > 0.05). The side effects were pain, burning sensation, itching, erythema, desquamation, slight edema, slight exudation, and hyperpigmentation. All of which were tolerable and recovered in a few days. The combined therapy of ALA-PDT and IPL showed an effective option for rosacea with a safety profile.

Rosacea: Treatment targets based on new physiopathology data

Over the past 15 years, numerous clinical, epidemiological and physiopathological articles have been published on rosacea. There is now increasing evidence that rosacea is an inflammatory disease characterised by abnormal innate immune response, major vascular changes, and increased colonisation by Demodex mites, along with a genetic predisposition and multiple external aggravating factors. It is thus possible to define treatment targets and possible treatments: 1) permanent vascular changes (medical and instrumental treatments); 2) flushing (betablockers, botulinum toxin); 3) innate immunity (antibiotics, nonspecific antioxidants and anti-inflammatory molecules); 4) a neurovascular component (analgesics, antidepressants); 5) Demodex (antiparasitic drugs); 6) microbiome; 7) skin barrier impairment (cosmetics and certain systemic drugs); 8) sebaceous glands (isotretinoin, surgery); 9) environmental factors (alcohol, coffee, UV exposure). Treatment recommendations are now available in many countries and benefit from the new phenotypic approach to rosacea, in which every sign or symptom is considered separately rather than having to deal with overlapping subtypes. Since the 2000s, many good quality clinical trials have been published in the field of rosacea and many others are still ongoing. Rosacea is a complex disease involving many different mechanisms and with numerous possible treatments, but there are still some important unmet needs with regard to optimal care.

Facial Skin Microbiota-Mediated Host Response to Pollution Stress Revealed by Microbiome Networks of Individual

Urban living has been reported to cause various skin disorders. As an integral part of the skin barrier, the skin microbiome is among the key factors associated with urbanization-related skin alterations. The role of skin microbiome in mediating the effect of urban stressors (e.g., air pollutants) on skin physiology is not well understood. We generated 16S sequencing data and constructed a microbiome network of individual (MNI) to analyze the effect of pollution stressors on the microbiome network and its downstream mediation effect on skin physiology in a personalized manner. In particular, we found that the connectivity and fragility of MNIs significantly mediated the adverse effects of air pollution on skin health, and a smoking lifestyle deepened the negative effects of pollution stress on facial skin microbiota. This is the first study that describes the mediation effect of the microbiome network on the skin’s physiological response toward environmental factors as revealed by our newly developed MNI approach and conditional process analysis.

IMPORTANCE The association between the skin microbiome and skin health has been widely reported. However, the role of the skin microbiome in mediating skin physiology remains a challenging and yet priority subject in the field. Through developing a novel MNI method followed by mediation analysis, we characterized the network signature of the skin microbiome at an individual level and revealed the role of the skin microbiome in mediating the skin’s responses toward environmental stressors. Our findings may shed new light on microbiome functions in skin health and lay the foundation for the design of a microbiome-based intervention strategy in the future.

Sodium Bituminosulfonate Used to Treat Rosacea Modulates Generation of Inflammatory Mediators by Primary Human Neutrophils

Background

Sodium bituminosulfonate is derived from naturally occurring sulphur-rich oil shale and is used for the treatment of the inflammatory skin disease rosacea. Major molecular players in the development of rosacea include the release of enzymes that process antimicrobial peptides which, together with reactive oxygen species (ROS) and vascular endothelial growth factor (VEGF), promote pro-inflammatory processes and angiogenesis. The aim of this study was to address the molecular mechanism(s) underlying the therapeutic benefit of the formulation sodium bituminosulfonate dry substance (SBDS), which is indicated for the treatment of skin inflammation, including rosacea.

Methods

We investigated whether SBDS regulates the expression of cytokines, the release of the antimicrobial peptide LL-37, calcium mobilization, proteases (matrix metalloproteinase, elastase, kallikrein (KLK)5), VEGF or ROS in primary human neutrophils. In addition, activity assays with 5-lipoxygenase (5-LO) and recombinant human MMP9 and KLK5 were performed.

Results

We observed that SBDS reduces the release of the antimicrobial peptide LL-37, calcium, elastase, ROS and VEGF from neutrophils. Moreover, KLK5, the enzyme that converts cathelicidin to LL-37, and 5-LO that produces leukotriene (LT)A₄, the precursor of LTB₄, were both inhibited by SBDS with an IC₅₀ of 7.6 µg/mL and 33 µg/mL, respectively.

Conclusion

Since LTB₄ induces LL-37 which, in turn, promotes increased intracellular calcium levels and thereby, ROS/VEGF/elastase release, SBDS possibly regulates the LTB₄/LL-37/calcium – ROS/VEGF/elastase axis by inhibiting 5-LO and KLK5. Additional direct effects on other pro-inflammatory pathways such as ROS generation cannot be ruled out. In summary, SBDS reduces the generation of inflammatory mediators from human neutrophils possibly accounting for its anti-inflammatory effects in rosacea.

A positive feedback loop between mTORC1 and cathelicidin promotes skin inflammation in rosacea

Rosacea is a chronic inflammatory skin disorder whose pathogenesis is unclear. Here, several lines of evidence were provided to demonstrate that mTORC1 signaling is hyperactivated in the skin, especially in the epidermis, of both rosacea patients and a mouse model of rosacea-like skin inflammation. Both mTORC1 deletion in epithelium and inhibition by its specific inhibitors can block the development of rosacea-like skin inflammation in LL37-induced rosacea-like mouse model. Conversely, hyperactivation of mTORC1 signaling aggravated rosacea-like features. Mechanistically, mTORC1 regulates cathelicidin through a positive feedback loop, in which cathelicidin LL37 activates mTORC1 signaling by binding to Toll-like receptor 2 (TLR2) and thus in turn increases the expression of cathelicidin itself in keratinocytes. Moreover, excess cathelicidin LL37 induces both NF-κB activation and disease-characteristic cytokine and chemokine production possibly via mTORC1 signaling. Topical application of rapamycin improved clinical symptoms in rosacea patients, suggesting mTORC1 inhibition can serve as a novel therapeutic avenue for rosacea.

Murine models of rosacea: a review

Rosacea is a chronic inflammatory disease characterized by facial flushing, erythema, telangiectasia, papules, and pustules. Its pathogenesis has not been fully understood. In 2017, the global ROSacea COnsensus (ROSCO) panel updated the diagnosis, classification, and assessment of rosacea. Phenotype-based treatments and long-term managements have also been recommended. Murine models are a powerful tool in unveiling and dissecting the mechanisms of human diseases. Here, we summarized murine models of rosacea developed or used in previous research, including LL-37 intradermal injection model, KLK-5-induced inflammation model, croton oil inflammation model, 12-O-Tetradecanoylphorbol-13-acetate inflammation model, arachidonic acid inflammation model, RTX-induced vasodilation model, and UVB-induced model. LL-37 injection model has become the most intensively used model in rosacea research. Each model could show the pathophysiological and clinical features of rosacea to some extent. However, no model can show the full picture of the characteristics of rosacea. Improving existed murine models, developing new murine models, and applying them to pathogenesis and treatment research on rosacea are highly warranted in the future.

Coptis chinensis Franch Directly Inhibits Proteolytic Activation of Kallikrein 5 and Cathelicidin Associated with Rosacea in Epidermal Keratinocytes

Rosacea is a common and chronic inflammatory skin disease that is characterized by dysfunction of the immune and vascular system. The excessive production and activation of kallikerin 5 (KLK5) and cathelicidin have been implicated in the pathogenesis of rosacea. Coptis chinensis Franch (CC) has been used as a medicinal herb in traditional oriental medicine. However, little is known about the efficacy and mechanism of action of CC in rosacea. In this study, we evaluate the effect of CC and its molecular mechanism on rosacea in human epidermal keratinocytes. CC has the capacity to downregulate the expression of KLK5 and cathelicidin, and also inhibits KLK5 protease activity, which leads to reduced processing of inactive cathelicidin into active LL-37. It was determined that CC ameliorates the expression of pro-inflammatory cytokines through the inhibition of LL-37 processing. In addition, it was confirmed that chitin, an exoskeleton of Demodex mites, mediates an immune response through TLR2 activation, and CC inhibits TLR2 expression and downstream signal transduction. Furthermore, CC was shown to inhibit the proliferation of human microvascular endothelial cells induced by LL-37, the cause of erythematous rosacea. These results demonstrate that CC improved rosacea by regulating the immune response and angiogenesis, and revealed its mechanism of action, indicating that CC may be a useful therapeutic agent for rosacea.

Practical context of enzymatic treatment for wound healing: A secreted protease approach (Review)

Skin wounds have been extensively studied as their healing represents a critical step towards achieving homeostasis following a traumatic event. Dependent on the severity of the damage, wounds are categorized as either acute or chronic. To date, chronic wounds have the highest economic impact as long term increases wound care costs. Chronic wounds affect 6.5 million patients in the United States with an annual estimated expense of $25 billion for the health care system. Among wound treatment categories, active wound care represents the fastest-growing category due to its specific actions and lower costs. Within this category, proteases from various sources have been used as successful agents in debridement wound care. The wound healing process is predominantly mediated by matrix metalloproteinases (MMPs) that, when dysregulated, result in defective wound healing. Therapeutic activity has been described for animal secretions including fish epithelial mucus, maggot secretory products and snake venom, which contain secreted proteases (SPs). No further alternatives for use, sources or types of proteases used for wound healing have been found in the literature to date. Through the present review, the context of enzymatic wound care alternatives will be discussed. In addition, substrate homology of SPs and human MMPs will be compared and contrasted. The purpose of these discussions is to identify and propose the stages of wound healing in which SPs may be used as therapeutic agents to improve the wound healing process.

Potential association between rosacea and cancer: A study in a medical center in southern China

Growing evidence suggests that rosacea increases the risk of systemic diseases, but studies of the relationships between rosacea and cancer are rare. Aimed to assess the relationship between rosacea and cancer, a total of 7548 patients with confirmed internal malignancies and 8340 cancer-free individuals aged 18 years or more were included in this study from November 2015 to October 2017. Clinical characteristics, personal history and laboratory data were recorded when patients were diagnosed with rosacea. Logistic regression analyses were performed to analyze associations between cancer and rosacea. We found rosacea significantly affected more women than men in both cancer and cancer-free group. The data showed there was no relationship between rosacea and lung, gastrointestinal, nasopharyngeal and gynecological cancer. However, rosacea was significantly associated with the increased risk of breast cancer and glioma, but negatively associated with the risk of hematological cancer. Of the 190 female breast cancer patients with rosacea, 98.95% had the erythematotelangiectatic subtype of rosacea, 48.42% had chloasma and 76.31% of them were Fitzpatrick skin type III and IV. In our binary regression model, breast cancer patients with rosacea had a higher prevalence of estrogen receptor-positive status, lower high-density lipoprotein levels and higher low-density lipoprotein than patients with breast cancer but no rosacea. Our findings indicate that rosacea is significantly associated with higher incidence of breast cancer, glioma and lower prevalence of hematological cancer.

Cationic Intrinsically Disordered Antimicrobial Peptides (CIDAMPs) Represent a New Paradigm of Innate Defense with a Potential for Novel Anti-Infectives

In the search for potential mechanisms underlying the remarkable resistance of healthy skin against infection by soil bacteria like Pseudomonas (P.) aeruginosa we identified fragments of the intrinsically disordered protein hornerin as potent microbicidal agents in the stratum corneum. We found that, independent of the amino acid (AA)-sequence, any tested linear cationic peptide containing a high percentage of disorder-promoting AA and a low percentage of order-promoting AA is a potent microbicidal antimicrobial. We further show that the antimicrobial activity of these cationic intrinsically disordered antimicrobial peptides (CIDAMPs) depends on the peptide chain length, its net charge, lipidation and environmental conditions. The ubiquitous presence of latent CIDAMP sources in nature suggests a common and yet overlooked adapted innate disinfection system of body surfaces. The simple structure and virtually any imaginable sequence or composition of disorder-promoting AA allow the generation of a plethora of CIDAMPs. These are potential novel microbicidal anti-infectives for various bacterial pathogens, including P. aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA) and fungal pathogens like Candida albicans and Cryptococcus neoformans.

Recent advances in understanding and managing rosacea

Rosacea is a common chronic inflammatory skin disease of the central facial skin and is of unknown origin. Currently, two classifications of rosacea exist that are based on either "preformed" clinical subtypes (erythematotelangiectatic, papulopustular, phymatous, and ocular) or patient-tailored analysis of the presented rosacea phenotype. Rosacea etiology and pathophysiology are poorly understood. However, recent findings indicate that genetic and environmental components can trigger rosacea initiation and aggravation by dysregulation of the innate and adaptive immune system. Trigger factors also lead to the release of various mediators such as keratinocytes (for example, cathelicidin, vascular endothelial growth factor, and endothelin-1), endothelial cells (nitric oxide), mast cells (cathelicidin and matrix metalloproteinases), macrophages (interferon-gamma, tumor necrosis factor, matrix metalloproteinases, and interleukin-26), and T helper type 1 (T _H1) and T _H17 cells. Additionally, trigger factors can directly communicate to the cutaneous nervous system and, by neurovascular and neuro-immune active neuropeptides, lead to the manifestation of rosacea lesions. Here, we aim to summarize the recent advances that preceded the new rosacea classification and address a symptom-based approach in the management of patients with rosacea.

Elevated Tear Human Neutrophil Peptides 1-3, Human Beta Defensin-2 Levels and Conjunctival Cathelicidin LL-37 Gene Expression in Ocular Rosacea

Purpose: To investigate the role of innate immunity in ocular rosacea. Methods: Thirty-two patients with ocular rosacea patients (group-1) and 28 healthy volunteers (group-2) who served as controls were enrolled in the study. Tear function parameters were assessed, conjunctival impression cytology was performed and tear samples were collected. Human-neutrophil-peptides (HNP) 1-3 and human-beta-defensin-2 (hBD-2) levels were measured in tears by using ELISA tests. Cathelicidin leucin-leucin-37 (LL-37), hBD-2, human-beta-defensin-9 (hBD-9) gene expression levels were measured in the conjunctival impression cytology samples using real-time polymerase chain reaction. Results: Tear HNP1-3 (p = 0.024), hBD-2 (p < 0.001), conjunctival LL-37 gene expression rate (p = 0.014) and ocular surface disease index scores (p = 0.001) were higher and the tear break-up time was lower (p = 0.003) in group-1. No other differences were found between the groups. Conclusion: The results of this study suggest the role of abnormal innate immunity in the pathophysiology of ocular rosacea by revealing elevated antimicrobial peptide levels.

Protease-mediated Inflammation: An In Vitro Human Keratinocyte-based Screening Tool for Anti-inflammatory Drug Nanocarrier Systems

Background:

Refined encapsulation approaches in dermatotherapy gain increased interest. There is need of reproducible in vitro systems representing disease features to screen drug delivery systems for preclinical assessment. Inflammatory human skin diseases are commonly accompanied by abnormal epidermal differentiation and barrier impairment. Serine proteases (SPs) and their inhibitors play a critical role in such dysfunctional differentiation. SPs also initiate cellular pathways via activation of protease-activated receptors, which contribute to inflammation. Thus, function and activity of SPs should be considered for the design of new therapies of such disorders.

Objectives:

Herein, we established a novel simplified cell culture model, based on SP-mediated inflammation suitable to assess nanocarriers loaded with anti-inflammatory drugs.

Methods:

SP-mediated inflammation and the regulatory effect of free or encapsulated dexamethasone were determined by measuring interleukin-6 and interleukin-8 in culture medium of HaCaT (human adult low calcium temperature)-keratinocytes. Additionally, radical formation was analyzed by electron paramagnetic resonance spectroscopy. Cellular uptake of core-multishell nanocarriers was investigated by fluorescence microscopy. Cytotoxicity of all additives was determined by a viability assay.

Results:

SP-Stimulation of keratinocytes resulted in increased radical production and release of inflammatory cytokines without affecting cell viability. Induced inflammation was successfully downregulated by addition of free or encapsulated dexamethasone.

Conclusion:

SP-addition can be used as inflammatory stimulus in cell culture to mimic effects of aberrant enzymatic activities found in skin of atopic dermatitis patients. The set-up is appropriate as a preliminary test to examine the effectiveness of new molecules or delivery-systems to counteract serine protease-mediated inflammatory processes prior to skin studies.

The Evaluation of Contact Sensitivity with Standard and Cosmetic Patch Test Series in Rosacea Patients

Background

Rosacea is a common dermatosis characterized by erythema, telangiectasia, papules and pustules.

Objective

We aimed to evaluate contact sensitivity in the rosacea patients.

Methods

We included 65 rosacea patients and 60 healthy volunteers in the study. The patient and control groups were patch tested with European baseline series and cosmetic series.

Results

A positive reaction to at least 1 allergen in the European standard series was found in 32.3% of rosacea patients and 20.0% of subjects in the control group while the relevant numbers were 30.8% of rosacea patients and 10% of controls with the cosmetic series (p=0.08). In total, we found a positive reaction to at least 1 allergen in 38.5% of patients and 25.0% of controls (p=0.15). We did not find a statistically significant relationship between a positive reaction to 1 allergen in total and the gender, skin type, rosacea type, ocular involvement, age and disease duration. There were more symptoms in patients with a positive reaction to allergens (p<0.001).

Conclusion

Contact sensitivity was detected more common in rosacea patients. Patch testing may be useful in the treatment and follow up of rosacea patients especially if symptoms such as itching, burning and stinging are present.

Regulation of kallikrein-related peptidases in the skin – from physiology to diseases to therapeutic options

Kallikrein-related peptidases (KLKs) constitute a family of 15 highly conserved serine proteases, which show a tissue-specific expression profile. This made them valuable tumour expression markers. It became evident that KLKs are involved in many physiological processes like semen liquefaction and skin desquamation. More recently, we have learnt that they are involved in many pathophysiological conditions and diseases making them promising target of therapeutic intervention. Therefore, regulation of KLKs raised the interest of numerous reports. Herein, we summarise the current knowledge on KLKs regulation with an emphasis on skin-relevant KLKs regulation processes. Regulation of KLKs takes place on the level of transcription, on protease activation and on protease inactivation. A variety of protease inhibitors has been described to interact with KLKs including the irreversible serine protease inhibitors (SERPINs) and the reversible serine protease inhibitors of Kazal-type (SPINKs). In an attempt to integrate current knowledge, we propose that KLK regulation has credentials as targets for therapeutic intervention.

PAL-12, a new anti-aging hexa-peptoid, inhibits UVB-induced photoaging in human dermal fibroblasts and 3D reconstructed human full skin model, Keraskin-FT™

Peptoids are a class of peptidomimetics whose pharmacological activities are widely investigated owing to their remarkable biological stability. However, the utilities of peptoids as cosmetic functional ingredients have not been fully explored. Here, we investigated anti-aging effects of PAL-12, a new hexa-peptoid, on UVB-induced photoaging in human dermal fibroblasts (HDFs) and a 3D reconstituted human full skin model, Keraskin-FT™. PAL-12 suppressed matrix metalloproteinase-1 (MMP-1) expression induced by UVB irradiation along with the attenuation of MMP-1 secretion as determined by ELISA assay. Interestingly PAL-12 slightly enhanced the expression levels of collagen-1 and fibronectin-1 in HDFs or Keraskin-FT™. In addition, PAL-12 prevented the decrease of cell viability following UVB irradiation. However, PAL-12 failed to affect ROS generation, cell necrosis and apoptosis significantly. Instead, PAL-12 suppressed UVB-induced activation of epidermal growth factor receptors (EGFR), extracellular signal-regulated kinase (ERK) and c-Jun, which may resulted in the attenuation of AP-1-promoted MMP-1 expression. Collectively, these results suggest that PAL-12 might be a novel cosmetic ingredient effective against UVB-induced skin photoaging.

Identification of bacterial biofilm and the Staphylococcus aureus derived protease, staphopain, on the skin surface of patients with atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by an impaired epidermal barrier, dysregulation of innate and adaptive immunity, and a high susceptibility to bacterial colonization and infection. In the present study, bacterial biofilm was visualized by electron microscopy at the surface of AD skin. Correspondingly, Staphylococcus aureus (S. aureus) isolates from lesional skin of patients with AD, produced a substantial amount of biofilm in vitro. S. aureus biofilms showed less susceptibility to killing by the antimicrobial peptide LL-37 when compared with results obtained using planktonic cells. Confocal microscopy analysis showed that LL-37 binds to the S. aureus biofilms. Immuno-gold staining of S. aureus biofilm of AD skin detected the S. aureus derived protease staphopain adjacent to the bacteria. In vitro, staphopain B degraded LL-37 into shorter peptide fragments. Further, LL-37 significantly inhibited S. aureus biofilm formation, but no such effects were observed for the degradation products. The data presented here provide novel information on staphopains present in S. aureus biofilms in vivo, and illustrate the complex interplay between biofilm and LL-37 in skin of AD patients, possibly leading to a disturbed host defense, which facilitates bacterial persistence.

Preliminary investigations into developing all-D Omiganan for treating Mupirocin-resistant MRSA skin infections

Staphylococcus aureus is the primary pathogen responsible for the majority of human skin infections, and meticillin-resistant S. aureus (MRSA) currently presents a major clinical concern. The overuse of Mupirocin, the first-line topical antibacterial drug over 30 years, has led to the emergence of Mupirocin-resistant MRSA, creating a clinical concern. The antimicrobial peptide Omiganan was touted to be a promising antibacterial drug candidate due to its rapid membrane-disrupting bactericidal mode of action, entering clinical trials in 2005 as a topical gel to prevent catheter site infections. However, drug development ceased in 2009 due to a lack of efficacy. We postulate this to be due to proteolytic degradation caused by endogenous human skin proteases. Herein, we tested our hypothesis using Omiganan and its all-D enantiomer in a human skin protease stability assay, followed by anti-MRSA activity assay against of a panel of clinical MRSA isolates, a bactericidal/static determination and a time-kill assay to gauge all-D Omiganan's potential for further topical antibacterial drug development.

Friends or Foes? Host defense (antimicrobial) peptides and proteins in human skin diseases

Host defense peptides/proteins (HDPs), also known as antimicrobial peptides/proteins (AMPs), are key molecules in the cutaneous innate immune system. AMPs/HDPs historically exhibit broad-spectrum killing activity against bacteria, enveloped viruses, fungi and several parasites. Recently, AMPs/HDPs were shown to have important biological functions, including inducing cell proliferation, migration and differentiation; regulating inflammatory responses; controlling the production of various cytokines/chemokines; promoting wound healing; and improving skin barrier function. Despite the fact that AMPs/HDPs protect our body, several studies have hypothesized that these molecules actively contribute to the pathogenesis of various skin diseases. For example, AMPs/HDPs play crucial roles in the pathological processes of psoriasis, atopic dermatitis, rosacea, acne vulgaris, systemic lupus erythematosus and systemic sclerosis. Thus, AMPs/HDPs may be a double-edged sword, promoting cutaneous immunity while simultaneously initiating the pathogenesis of some skin disorders. This review will describe the most common skin-derived AMPs/HDPs (defensins, cathelicidins, S100 proteins, ribonucleases and dermcidin) and discuss the biology and both the positive and negative aspects of these AMPs/HDPs in skin inflammatory/infectious diseases. Understanding the regulation, functions and mechanisms of AMPs/HDPs may offer new therapeutic opportunities in the treatment of various skin disorders.

Topical Treatment of Rosacea with Ivermectin Inhibits Gene Expression of Cathelicidin Innate Immune Mediators, LL-37 and KLK5, in Reconstructed and Ex Vivo Skin Models

Introduction

Numerous intrinsic and extrinsic factors have been associated with the pathophysiology of rosacea, including dysregulation of innate immunity. A high level of cathelicidin antimicrobial peptides (e.g., LL-37) has been shown in the facial skin of patients with rosacea. Excessive production of both LL-37 and KLK5, the serine protease responsible for its cleavage, has been suggested to play a role in the pathophysiology of rosacea. Ivermectin 10 mg/g cream, indicated for the treatment of inflammatory lesions of rosacea, is reported to have dual anti-parasitic and anti-inflammatory properties. However, the exact mechanism of action of ivermectin cream in the treatment of rosacea is unknown.

Methods

This study aimed to evaluate the effect of ivermectin on the expression of KLK5 and the subsequent effect on the maturation process of cathelicidins. Experimental studies were performed either on normal human epidermal keratinocytes (NHEK), reconstructed human epidermis (RHE) or on human skin ex vivo stimulated with calcitriol (1α,25-dihydroxyvitamin D3), which is known to induce KLK5 and LL-37 expression.

Results

The results show that ivermectin is able to inhibit KLK5 and CAMP gene expression and protein secretion in NHEK cells stimulated with calcitriol. Those results were confirmed in 3D models of the skin (RHE and skin ex vivo). The anti-inflammatory effects of ivermectin were associated with an inhibition of IL-8, IL-6 and MCP-1 (CCL2) secretion from NHEK cells.

Conclusions

These results suggest that ivermectin can prevent the inflammatory effects of rosacea triggered by abnormal LL-37 processing, through the inhibition of KLK5 gene expression in the epidermis.

Funding: Nestlé Skin Health R&D.

Electronic supplementary material

The online version of this article (doi:10.1007/s13555-017-0176-3) contains supplementary material, which is available to authorized users.

Tissue Kallikrein Inhibitors Based on the Sunflower Trypsin Inhibitor Scaffold - A Potential Therapeutic Intervention for Skin Diseases

Tissue kallikreins (KLKs), in particular KLK5, 7 and 14 are the major serine proteases in the skin responsible for skin shedding and activation of inflammatory cell signaling. In the normal skin, their activities are controlled by an endogenous protein protease inhibitor encoded by the SPINK5 gene. Loss-of-function mutations in SPINK5 leads to enhanced skin kallikrein activities and cause the skin disease Netherton Syndrome (NS). We have been developing inhibitors based on the Sunflower Trypsin Inhibitor 1 (SFTI-1) scaffold, a 14 amino acids head-to-tail bicyclic peptide with a disulfide bond. To optimize a previously reported SFTI-1 analogue (I10H), we made five analogues with additional substitutions, two of which showed improved inhibition. We then combined those substitutions and discovered a variant (Analogue 6) that displayed dual inhibition of KLK5 (tryptic) and KLK7 (chymotryptic). Analogue 6 attained a tenfold increase in KLK5 inhibition potency with an Isothermal Titration Calorimetry (ITC) K_d of 20nM. Furthermore, it selectively inhibits KLK5 and KLK14 over seven other serine proteases. Its biological function was ascertained by full suppression of KLK5-induced Protease-Activated Receptor 2 (PAR-2) dependent intracellular calcium mobilization and postponement of Interleukin-8 (IL-8) secretion in cell model. Moreover, Analogue 6 permeates through the cornified layer of in vitro organotypic skin equivalent culture and inhibits protease activities therein, providing a potential drug lead for the treatment of NS.

Skin barrier in rosacea

Recent studies about the cutaneous barrier demonstrated consistent evidence that the stratum corneum is a metabolically active structure and also has adaptive functions, may play a regulatory role in the inflammatory response with activation of keratinocytes, angiogenesis and fibroplasia, whose intensity depends primarily on the intensity the stimulus. There are few studies investigating the abnormalities of the skin barrier in rosacea, but the existing data already show that there are changes resulting from inflammation, which can generate a vicious circle caused a prolongation of flare-ups and worsening of symptoms. This article aims to gather the most relevant literature data about the characteristics and effects of the state of the skin barrier in rosacea.

Rosacea: Molecular Mechanisms and Management of a Chronic Cutaneous Inflammatory Condition

Rosacea is a chronic cutaneous inflammatory disease that affects the facial skin. Clinically, rosacea can be categorized into papulopustular, erythematotelangiectatic, ocular, and phymatous rosacea. However, the phenotypic presentations of rosacea are more heterogeneous. Although the pathophysiology of rosacea remains to be elucidated, immunologic alterations and neurovascular dysregulation are thought to have important roles in initiating and strengthening the clinical manifestations of rosacea. In this article, we present the possible molecular mechanisms of rosacea based on recent laboratory and clinical studies. We describe the genetic predisposition for rosacea along with its associated diseases, triggering factors, and suggested management options in detail based on the underlying molecular biology. Understanding the molecular pathomechanisms of rosacea will likely aid toward better comprehending its complex pathogenesis.

Cutaneous rosacea: a thorough overview of pathogenesis, clinical presentations, and current recommendations on management

The review summarizes and systemizes available international data on the pathogenesis, clinical manifestations and current recommendations for the management of rosacea patients.

Erythemato-telangiectatic rosacea: analysis of effectivity of treatment by flavonoid-rich topical agents

Rosacea is a common non-infectious disease with intricate aetiology involving endogenous, systemic or local, and environmental factors. Vascular changes may play a major role in rosacea pathogenesis. Chrysanthellum indicum extract contains a unique combination of component which has a beneficial effect on vascular wall permeability and increases the mechanical resistance of capillaries. The aim of the study is to investigate clinical and epidemiologic features of rosacea as well as to evaluate the efficacy and tolerability of external medication - flavonoid-rich plant extract-based cream Ruboril - in patients with erythemato-telangiectatic subtype of rosacea. Material and methods. We observed 52 patients (16 male and 36 female) aged from 23 to 69 with erythemato-telangiectatic subtype of rosacea. The diagnosis was established on the base of clinical presentation with regard to major and minor diagnostic criteria. In order to evaluate the efficacy of topical therapy with Ruboril cream a scale from 0 to 3 was used assessing the severity grade of erythema and teleangiectasias before treatment and after the 4th, 8th and 12th week of therapy. Results. Women were more often affected than men (69%). Patients of the age group from 40 years prevailed (75%). Fitzpatrick skin phototype II was revealed in 30 (58%) of patients. The most common provoking factors were meteorological (77%), emotional stress (67%), sauna/hot baths or alcohol (66%), hot drinks (48%). The prevailing areas of affection were cheeks (98%), forehead (54%), chin (48%), nose (52%). Moderate erythema was observed in 29 (56%) of patients, severe erythema in 15 (29%). Moderate grade of telangiectasias was registered in 30 (58%) of patients, numerous telangiectasias in 16 (31%). Topical application of cream Ruboril allowed to achieve good immediate results: the severity of erythema was reduced by 63%, the manifestation of telangiectasias decreased by 63%. Conclusion. Clinico-epidemiologic features of patients with erythemato-telangiectatic subtype of rosacea are as follows: erythematous and telangiectatic eruption on the cheeks, nose, and chin, weather and emotional influences, predominance of the female gender, skin phototype II, age > 40 years. The external medication Ruboril showed its high efficacy and safety in the treatment of patients with erythemato-telangiectatic subtype of rosacea which allowed to achieve good immediate results with erythema severity reduction of 63% and the decrease in the manifestation of telangiectasias of 63%.

Update on the Management of Rosacea

Refining diagnostic criteria has identified key characteristics differentiating rosacea, a chronic skin disorder, from other common cutaneous inflammatory conditions. The current classification system developed by the National Rosacea Society Expert Committee consists of erythematotelangiectatic, papulopustular, phymatous, and ocular subtypes. Each subtype stands as a unique entity among a spectrum, with characteristic symptoms and physical findings, along with an intricate pathophysiology. The main treatment modalities for rosacea include topical, systemic, laser, and light therapies. Topical brimonidine tartrate gel and calcineurin inhibitors are at the forefront of topical therapies, alone or in combination with traditional therapies such as topical metronidazole or azelaic acid and oral tetracyclines or isotretinoin. Vascular laser and intense pulsed light therapies are beneficial for the erythema and telangiectasia, as well as the symptoms (itching, burning, pain, stinging, swelling) of rosacea. Injectable botulinum toxin, topical ivermectin, and microsecond long-pulsed neodymium-yttrium aluminum garnet laser are emerging therapies that may prove to be extremely beneficial in the future. Once a debilitating disorder, rosacea has become a well known and manageable entity in the setting of numerous emerging therapeutic options. Herein, we describe the treatments currently available and give our opinions regarding emerging and combination therapies.

Kallikreins - The melting pot of activity and function

The human tissue kallikrein and kallikrein-related peptidases (KLKs), encoded by the largest contiguous cluster of protease genes in the human genome, are secreted serine proteases with diverse expression patterns and physiological roles. Because of the broad spectrum of processes that are modulated by kallikreins, these proteases are the subject of extensive investigations. This review brings together basic information about the biochemical properties affecting enzymatic activity, with highlights on post-translational modifications, especially glycosylation. Additionally, we present the current state of knowledge regarding the physiological functions of KLKs in major human organs and outline recent discoveries pertinent to the involvement of kallikreins in cell signaling and in viral infections. Despite the current depth of knowledge of these enzymes, many questions regarding the roles of kallikreins in health and disease remain unanswered.

Rosacea: prevalence, pathogenesis, particular features of clinical manifestations

This literature review examines principal aspects of rosacea prevalence in the Russian Federation and abroad, shows present-day opinions about the pathogenesis and histological picture of rosacea and presents actual classification and a number of key clinical forms of the disease.

Update on the management of rosacea

Refining diagnostic criteria has identified key characteristics differentiating rosacea, a chronic skin disorder, from other common cutaneous inflammatory conditions. The current classification system developed by the National Rosacea Society Expert Committee consists of erythematotelangiectatic, papulopustular, phymatous, and ocular subtypes. Each subtype stands as a unique entity among a spectrum, with characteristic symptoms and physical findings, along with an intricate pathophysiology. The main treatment modalities for rosacea include topical, systemic, laser, and light therapies. Topical brimonidine tartrate gel and calcineurin inhibitors are at the forefront of topical therapies, alone or in combination with traditional therapies such as topical metronidazole or azelaic acid and oral tetracyclines or isotretinoin. Vascular laser and intense pulsed light therapies are beneficial for the erythema and telangiectasia, as well as the symptoms (itching, burning, pain, stinging, swelling) of rosacea. Injectable botulinum toxin, topical ivermectin, and microsecond long-pulsed neodymium-yttrium aluminum garnet laser are emerging therapies that may prove to be extremely beneficial in the future. Once a debilitating disorder, rosacea has become a well known and manageable entity in the setting of numerous emerging therapeutic options. Herein, we describe the treatments currently available and give our opinions regarding emerging and combination therapies.

Gene expression profiling in pachyonychia congenita skin

BACKGROUND

Pachyonychia congenita (PC) is a skin disorder resulting from mutations in keratin (K) proteins including K6a, K6b, K16, and K17. One of the major symptoms is painful plantar keratoderma. The pathogenic sequelae resulting from the keratin mutations remain unclear.

OBJECTIVE

To better understand PC pathogenesis.

METHODS

RNA profiling was performed on biopsies taken from PC-involved and uninvolved plantar skin of seven genotyped PC patients (two K6a, one K6b, three K16, and one K17) as well as from control volunteers. Protein profiling was generated from tape-stripping samples.

RESULTS

A comparison of PC-involved skin biopsies to adjacent uninvolved plantar skin identified 112 differentially-expressed mRNAs common to patient groups harboring K6 (i.e., both K6a and K6b) and K16 mutations. Among these mRNAs, 25 encode structural proteins including keratins, small proline-rich and late cornified envelope proteins, 20 are related to metabolism and 16 encode proteases, peptidases, and their inhibitors including kallikrein-related peptidases (KLKs), and serine protease inhibitors (SERPINs). mRNAs were also identified to be differentially expressed only in K6 (81) or K16 (141) patient samples. Furthermore, 13 mRNAs were identified that may be involved in pain including nociception and neuropathy. Protein profiling, comparing three K6a plantar tape-stripping samples to non-PC controls, showed changes in the PC corneocytes similar, but not identical, to the mRNA analysis.

CONCLUSION

Many differentially-expressed genes identified in PC-involved skin encode components critical for skin barrier homeostasis including keratinocyte proliferation, differentiation, cornification, and desquamation. The profiling data provide a foundation for unraveling the pathogenesis of PC and identifying targets for developing effective PC therapeutics.

Expression of human skin-specific genes defined by transcriptomics and antibody-based profiling

To increase our understanding of skin, it is important to define the molecular constituents of the cell types and epidermal layers that signify normal skin. We have combined a genome-wide transcriptomics analysis, using deep sequencing of mRNA from skin biopsies, with immunohistochemistry-based protein profiling to characterize the landscape of gene and protein expression in normal human skin. The transcriptomics and protein expression data of skin were compared to 26 (RNA) and 44 (protein) other normal tissue types. All 20,050 putative protein-coding genes were classified into categories based on patterns of expression. We found that 417 genes showed elevated expression in skin, with 106 genes expressed at least five-fold higher than that in other tissues. The 106 genes categorized as skin enriched encoded for well-known proteins involved in epidermal differentiation and proteins with unknown functions and expression patterns in skin, including the C1orf68 protein, which showed the highest relative enrichment in skin. In conclusion, we have applied a genome-wide analysis to identify the human skin-specific proteome and map the precise localization of the corresponding proteins in different compartments of the skin, to facilitate further functional studies to explore the molecular repertoire of normal skin and to identify biomarkers related to various skin diseases.

Recent advances in the understanding and management of rosacea

Rosacea is a chronic relapsing inflammatory facial dermatosis. There are several known triggers but the pathogenesis remains unknown. Recent achievements in understanding this disease point to the importance of skin-environmental interactions. This includes physical and chemical factors, but also microbial factors. The impairment of the skin barrier function and the activation of the innate immune defences are major and connected pathways contributing to an ongoing inflammatory response in the affected skin. This becomes modulated by endogenous factors like neurovascular, drugs, and psychological factors. These factors offer new therapeutic targets for rosacea treatment. There is a broader range of anti-inflammatory compounds available with a favourable safety record. Only recently have persistent erythema and flushing been addressed by new drug formulations.

Sphingolipids and antimicrobial peptides: function and roles in atopic dermatitis

Inflammatory skin diseases such as atopic dermatitis (AD) and rosacea were complicated by barrier abrogation and deficiency in innate immunity. The first defender of epidermal innate immune response is the antimicrobial peptides (AMPs) that exhibit a broad-spectrum antimicrobial activity against multiple pathogens, including Gram-positive and Gram-negative bacteria, viruses, and fungi. The deficiency of these AMPs in the skin of AD fails to protect our body against virulent pathogen infections. In contrast to AD where there is a suppression of AMPs, rosacea is characterized by overexpression of cathelicidin antimicrobial peptide (CAMP), the products of which result in chronic epidermal inflammation. In this regard, AMP generation that is controlled by a key ceramide metabolite S1P-dependent mechanism could be considered as alternate therapeutic approaches to treat these skin disorders, i.e., Increased S1P levels strongly stimulated the CAMP expression which elevated the antimicrobial activity against multiple pathogens resulting the improved AD patient skin.

New insights into rosacea pathophysiology: a review of recent findings

Rosacea is a common, chronic inflammatory skin disease of poorly understood origin. Based on its clinical features (flushing, chronic inflammation, fibrosis) and trigger factors, a complex pathobiology involving different regulatory systems can be anticipated. Although a wealth of research has shed new light over recent years on its pathophysiology, the precise interplay of the various dysregulated systems (immune, vascular, nervous) is still poorly understood. Most authors agree on 4 major clinical subtypes of rosacea: erythematotelangiectatic rosacea, papulopustular rosacea, phymatous rosacea, and ocular rosacea. Still, it needs to be elucidated whether these subtypes develop in a consecutive serial fashion or if any subtypes may occur individually as part of a syndrome. Because rosacea often affects multiple family members, a genetic component is also suspected, but the genetic basis of rosacea remains unclear. During disease manifestation and early stage, the innate immune system and neurovascular dysregulation seem to be driving forces in rosacea pathophysiology. Dissection of major players for disease progression and in advanced stages is severely hampered by the complex activation of the innate and adaptive immune systems, enhanced neuroimmune communication, profound blood vessel and possibly lymphatic vessel changes, and activation of almost every resident cell in the skin. This review discusses some of the recent findings and aims to build unifying hypotheses for a modern understanding of rosacea pathophysiology.