Biomarkers in rosacea: A systematic review

Rosacea is a chronic and psychologically ladened disease affecting 1%-3% of people worldwide. The identification and validation of biomarkers in rosacea patients has the potential to improve disease progression, support diagnosis, provide objective measures for clinical trials and aid in management. The objective of this review is to systematically identify all rosacea biomarkers, categorize them by type and identify trends to improve disease expression. Eligibility criteria for this review (PROSPERO CRD42023397510) include randomized controlled trials, case-control studies, cohort studies and other observational studies. No restrictions were placed on patient demographics (age, sex, ethnicity) or language of publication until February 2023. Quality of studies was assessed using the National Institute of Health quality assessment tool. The literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A total of 805 unique articles were screened based on the applied inclusion and exclusion criteria. After the articles were screened based on title/abstract and full-text, a total of 38 studies were included, reporting on a total of 119 unique biomarkers. The results of this review and current rosacea pathogenic mechanisms provide the greatest support for the innate cathelicidin and inflammasome, Th1 and Th17 pathways. The most commonly reported biomarkers include IL-1β, TNF-α, IL-37, IFN-γ and MMP-9. Biomarkers identified in this study support current theories of rosacea pathogenesis and provide direction for research to further our knowledge. However, more research is needed to identify biomarkers panels that can provide diagnostic utility. This may be difficult due to the heterogeneity of the disease and potential differences between rosacea subtypes.

Rosacea in Older Adults and Pharmacologic Treatments

Rosacea is a chronic inflammatory skin condition that is often more severe in older patients. The main clinical features are erythema, telangiectasia, and inflammatory lesions of the face. The pathogenesis of this condition is not fully understood but certainly multifaceted. Immune and inflammatory dysregulation, genetics, neurogenic dysregulation, microbiome dysbiosis, and systemic disease have all been implicated in rosacea pathogenesis. As we better understand the various pathways that lead to rosacea, we acknowledge that the different symptoms may have unique underlying triggers and mechanisms. Aging also impacts rosacea diagnosis and treatment. Older adults have more severe rosacea symptoms while also having more sensitive and fragile skin than younger patients; therefore, rosacea treatments for older patients require a balance between delivering adequate potency while also minimizing skin irritation and other adverse effects. Until recently, rosacea diagnoses were based on concrete subtypes that did not necessarily capture each patient's manifestation of rosacea. There is now an emphasis on more personalized phenotype-based diagnoses and treatments, which allows for more emphasis on treating individual symptoms and accounting for the unique characteristics of older patients. Centrofacial erythema is best treated with brimonidine and oxymetazoline, while phymatous change and telangiectasia are best treated with surgery and laser ablation. Treatment for rosacea papules and pustules ranges from topicals, such as azelaic acid, ivermectin, metronidazole, minocycline, and encapsulated benzoyl peroxide, to systemics, such as doxycycline and isotretinoin. It is important to understand these treatments in relation to adverse effects and drug interactions that may specifically arise in older populations to provide optimal care. As we advance in understanding rosacea's pathogenesis and adopt personalized phenotype-based approaches, optimizing care for older patients becomes crucial. Continued research into novel treatments is essential to address their unique needs.

Erenumab for Treatment of Persistent Erythema and Flushing in Rosacea: A Nonrandomized Controlled Trial

Importance

Treatment of erythema and flushing in rosacea is challenging. Calcitonin gene-related peptide (CGRP) has been associated with the pathogenesis of rosacea, raising the possibility that inhibition of the CGRP pathway might improve certain features of the disease.

Objective

To examine the effectiveness, tolerability, and safety of erenumab, an anti-CGRP-receptor monoclonal antibody, for the treatment of rosacea-associated erythema and flushing.

Design, Setting, and Participants

This single-center, open-label, single-group, nonrandomized controlled trial was conducted between June 9, 2020, and May 11, 2021. Eligible participants included adults with rosacea with at least 15 days of either moderate to severe erythema and/or moderate to extreme flushing. No concomitant rosacea treatment was allowed throughout the study period. Visits took place at the Danish Headache Center, Copenhagen University Hospital, Rigshospitalet in Copenhagen, Denmark. Participants received 140 mg of erenumab subcutaneously every 4 weeks for 12 weeks. A safety follow-up visit was performed at week 20. Data analysis occurred from January 2023 to January 2024.

Intervention

140 mg of erenumab every 4 weeks for 12 weeks.

Main Outcomes and Measures

The primary outcome was mean change in the number of days with moderate to extreme flushing during weeks 9 through 12, compared with the 4-week run-in period (baseline). The mean change in number of days with moderate to severe erythema was a secondary outcome. Adverse events were recorded for participants who received at least 1 dose of erenumab. Differences in means were calculated with a paired t test.

Results

A total of 30 participants (mean [SD] age, 38.8 [13.1] years; 23 female [77%]; 7 male [23%]) were included, of whom 27 completed the 12-week study. The mean (SD) number of days with moderate to extreme flushing was reduced by -6.9 days (95% CI, -10.4 to -3.4 days; P < .001) from 23.6 (5.8) days at baseline. The mean (SD) number of days with moderate to severe erythema was reduced by -8.1 days (95% CI, -12.5 to -3.7 days; P < .001) from 15.2 (9.1) days at baseline. Adverse events included transient mild to moderate constipation (10 participants [33%]), transient worsening of flushing (4 participants [13%]), bloating (3 participants [10%]), and upper respiratory tract infections (3 participants [10%]), consistent with previous data. One participant discontinued the study due to a serious adverse event (hospital admission due to gallstones deemed unrelated to the study), and 2 participants withdrew consent due to lack of time.

Conclusions and Relevance

These findings suggest that erenumab might be effective in reducing rosacea-associated flushing and chronic erythema (participants generally tolerated the treatment well, which was consistent with previous data), and that CGRP-receptor inhibition holds potential in the treatment of erythema and flushing associated with rosacea. Larger randomized clinical trials are needed to confirm this finding.

Trial Registration

ClinicalTrials.gov Identifier: NCT04419259.

Elevated plasma levels of calcitonin gene-related peptide in individuals with rosacea: A cross-sectional case-control study

BACKGROUND

Understanding the role of calcitonin gene-related peptide (CGRP) in the pathogenesis of rosacea might provide new therapeutic avenues for individuals with this disease.

OBJECTIVE

To compare plasma levels of CGRP between individuals with rosacea and healthy controls.

METHODS

In this cross-sectional case-control study conducted in Copenhagen, Denmark, we collected blood samples from the antecubital vein from adults with rosacea and from healthy controls.

RESULTS

We enrolled 123 individuals with rosacea and 68 healthy controls. After adjusting for age and sex, plasma levels of CGRP were significantly higher in individuals with rosacea (mean, 95% confidence interval: 140.21 pmol/L, 128.50-151.92 pmol/L), compared with controls (110.77 pmol/L, 99.91-120.14 pmol/L, p = 0.002). Plasma levels of CGRP were not affected by age, sex, BMI, concomitant migraine, rosacea sub- or phenotype, concomitant disease or current treatment.

LIMITATIONS

Participants were not age-, sex- and BMI-matched.

CONCLUSIONS AND RELEVANCE

Elevated plasma levels of CGRP in individuals with rosacea suggest a role of CGRP in the pathogenesis of rosacea. Targeting CGRP signalling might hold therapeutic promise in people affected by this disease.

CLINICALTRIALS

GOV LISTING

NCT03872050.

Hematological parameters as diagnostic biomarkers for patients with rosacea

Rosacea is a chronic inflammatory skin disease. Systemic inflammation plays a vital role in the pathogenesis of rosacea. Many studies have reported hematological parameters as biomarkers for diseases with inflammatory processes. However, the diagnostic value of hematological parameters in rosacea remains a puzzle. This study involved 462 patients with rosacea, including erythematotelangiectatic rosacea (ETR, n = 179), papulopustular rosacea (PPR, n = 250), and phymatous rosacea (PhR, n = 33), and 924 healthy control subjects. Demographic, clinical, and laboratory information was collected and compared between rosacea subtypes. The hematological parameters of the patients and the healthy controls were compared retrospectively. The platelet volume (MPV) and platelet crit (PCT) were significantly upregulated, and the lower red cell distribution width (RDW) was significantly downregulated in rosacea compared to healthy controls, and they were identified as the diagnostic biomarkers for rosacea with area under the curve values of 0.828, 0.742, and 0.787, respectively. Comparing the hematological parameters among the three rosacea subtypes, we found that platelet-to-lymphocyte ratio and platelet-to-neutrophil ratio values in the ETR group were significantly higher than those in the PPR and PhR groups. The correlation between hematological parameters and clinical scores showed that RDW was negatively correlated with the Clinician Erythema Assessment score. However, there was no significant correlation between the Investigator Global Assessment score and hematological parameters. In conclusion, PCT, MPV, and RDW have diagnostic value for rosacea, and RDW is correlated with the severity of rosacea erythema, implying the potential applications of PCT, MPV, and RDW in the diagnosis and monitoring of rosacea.

Exploring the association between rosacea and acne by integrated bioinformatics analysis

Clinically, rosacea occurs frequently in acne patients, which hints the existence of shared signals. However, the connection between the pathophysiology of rosacea and acne are not yet fully understood. This study aims to unveil molecular mechanism in the pathogenesis of rosacea and acne. We identified differentially expressed genes (DEGs) by limma and weighted gene co-expression network analysis and screened hub genes by constructing a protein-protein interaction network. The hub genes were verified in different datasets. Then, we performed a correlation analysis between the hub genes and the pathways. Finally, we predicted and verified transcription factors of hub genes, performed the immune cell infiltration analysis using CIBERSORT, and calculated the correlation between hub genes and immune cells. A total of 169 common DEGs were identified, which were mainly enriched in immune-related pathways. Finally, hub genes were identified as IL1B, PTPRC, CXCL8, MMP9, CCL4, CXCL10, CD163, CCR5, CXCR4, and TLR8. 9 transcription factors that regulated the expression of hub genes were identified. The infiltration of γδT cells was significantly increased in rosacea and acne lesions and positively linked with almost all hub genes. These identified hub genes and immune cells may play a crucial role in the development of rosacea and acne.

Rosacea, microbiome and probiotics: the gut-skin axis

Rosacea is an inflammatory skin disease involving diverse symptoms with a variable clinical progress which can severely impact the patient's quality of life as well as their mental health. The pathophysiological model of rosacea involves an unbalanced immune system predisposed to excessive inflammation, in addition to vascular and nervous alterations, being certain cutaneous microorganisms' triggers of the symptoms onset. The gut-skin axis explains a bidirectional interaction between skin and gut microbiota in some inflammatory skin diseases such as atopic dermatitis, psoriasis, or rosacea. The introduction and consolidation of the next-generation sequencing in recent years has provided unprecedented information about the microbiome. However, the characterization of the gut and skin microbiota and the impact of the gut-skin axis in patients with rosacea has been little explored, in contrast to other inflammatory skin diseases such as atopic dermatitis or psoriasis. Furthermore, the clinical evolution of patients with rosacea is not always adequate and it is common for them to present a sustained symptomatology with frequent flare-ups. In this context, probiotic supplementation could improve the clinical evolution of these patients as happens in other pathologies. Through this review we aim to establish and compile the basics and directions of current knowledge to understand the mechanisms by which the microbiome influences the pathogenesis of rosacea, and how modulation of the skin and gut microbiota could benefit these patients.

Q-switched 1064 nm Nd: YAG laser restores skin photoageing by activating autophagy by TGFβ1 and ITGB1

Excessive ultraviolet B ray (UVB) exposure to sunlight results in skin photoageing. Our previous research showed that a Q-switched 1064 nm Nd: YAG laser can alleviate skin barrier damage through miR-24-3p. However, the role of autophagy in the laser treatment of skin photoageing is still unclear. This study aims to investigate whether autophagy is involved in the mechanism of Q-switched 1064 nm Nd: YAG in the treatment of skin ageing. In vitro, primary human dermal fibroblast (HDF) cells were irradiated with different doses of UVB to establish a cell model of skin photoageing. In vivo, SKH-1 hairless mice were irradiated with UVB to establish a skin photoageing mouse model and irradiated with laser. The oxidative stress and autophagy levels were detected by western blot, immunofluorescence and flow cytometer. String was used to predict the interaction protein of TGF-β1, and CO-IP and GST-pull down were used to detect the binding relationship between TGFβ1 and ITGB1. In vitro, UVB irradiation reduced HDF cell viability, arrested cell cycle, induced cell senescence and oxidative stress compared with the control group. Laser treatment reversed cell viability, senescence and oxidative stress induced by UVB irradiation and activated autophagy. Autophagy agonists or inhibitors can enhance or attenuate the changes induced by laser treatment, respectively. In vivo, UVB irradiation caused hyperkeratosis, dermis destruction, collagen fibres reduction, increased cellular senescence and activation of oxidative stress in hairless mice. Laser treatment thinned the stratum corneum of skin tissue, increased collagen synthesis and autophagy in the dermis, and decreased the level of oxidative stress. Autophagy agonist rapamycin and autophagy inhibitor 3-methyladenine (3-MA) can enhance or attenuate the effects of laser treatment on the skin, respectively. Also, we identified a direct interaction between TGFB1 and ITGB1 and participated in laser irradiation-activated autophagy, thereby inhibiting UVB-mediated oxidative stress further reducing skin ageing. Q-switched 1064 nm Nd: YAG laser treatment inhibited UVB-induced oxidative stress and restored skin photoageing by activating autophagy, and TGFβ1 and ITGB1 directly incorporated and participated in this process.

Development of a novel integrated isothermal amplification system for detection of bacteria-spiked blood samples

Bloodstream infection (BSI) caused by bacteria is highly pathogenic and lethal, and easily develops whole-body inflammatory state. Immediate identification of disease-causing bacteria can improve patient prognosis. Traditional testing methods are not only time-consuming, but such tests are limited to laboratories. Recombinase polymerase amplification combined with lateral flow dipstick (RPA-LFD) holds great promise for rapid nucleic acid detection, but the uncapping operation after amplification easily contaminates laboratories. Therefore, the establishment of a more effective integrated isothermal amplification system has become an urgent problem to be solved. In this study, we designed and fabricated a hermetically sealed integrated isothermal amplification system. Combining with this system, a set of RPA-LFD assays for detecting S. aureus, K. peneumoniae, P. aeruginosa, and H. influenza in BSI were established and evaluated. The whole process could be completed in less than 15 min and the results can be visualized by the naked eye. The developed RPA-LFD assays displayed a good sensitivity, and no cross-reactivity was observed in seven similar bacterial genera. The results obtained with 60 clinical samples indicated that the developed RPA-LFD assays had high specifcity and sensitivity for identifying S. aureus, K. peneumoniae, P. aeruginosa, and H. influenza in BSI. In conclusion, our results showed that the developed RPA-LFD assay is an alternative to existing PCR-based methods for detection of S. aureus, K. peneumoniae, P. aeruginosa, and H. influenza in BSI in primary hospitals.

An exploratory comparative case series of calcitonin gene-related peptide monoclonal antibodies in patients with migraine with rosacea

Rosacea is associated with &gt; 50% of cases of migraine. Recent data have shown that calcitonin gene-related peptide (CGRP) is elevated in rosacea skin. CGRP monoclonal antibodies (mAbs) prevent migraine with known safety profiles, but their effect on rosacea is not known. This exploratory retrospective study examined rosacea in patients with migraines, before and after CGRP mAbs. Of 13 eligible patients on stable or unchanged concurrent rosacea medications, the majority experienced improvement after receiving CGRP mAbs. Mean (SD) rosacea severity scores for the periods before and while on CGRP mAbs were, respectively, 1.19 (0.65) and 0.58 (0.70) (P = 0.01). Prospective, placebo-controlled clinical trials are needed to further assess the use of CGRP mAbs in rosacea.

MRGPRX2, drug pseudoallergies, inflammatory diseases, mechanisms and distinguishing MRGPRX2- and IgE/FcεRI-mediated events

MRGPRX2, a novel Gaq -coupled human mast cell receptor, mediates non-immune adverse reactions without the involvement of antibody priming. Constitutively expressed by human skin mast cells, MRGPRX2 modulates cell degranulation producing pseudoallergies manifesting as itch, inflammation and pain. The term pseudoallergy is defined in relation to adverse drug reactions in general and immune/non-immune-mediated reactions in particular. A list of drugs with MRGPRX2 activity is presented, including a detailed examination of three important and widely used approved therapies: neuromuscular blockers, quinolones and opioids. For the clinician, the significance of MRGPRX2 is considered as an aid in distinguishing and ultimately identifying specific immune and non-immune inflammatory reactions. Anaphylactoid/anaphylactic reactions, neurogenic inflammation and inflammatory diseases with a clear or strongly suspected association with MRGPRX2 activation are examined. Inflammatory diseases include chronic urticaria, rosacea, atopic dermatitis, allergic contact dermatitis, mastocytosis, allergic asthma, ulcerative colitis and rheumatoid arthritis. MRGPRX2- and allergic IgE/FcεRI-mediated reactions may be clinically similar. Importantly, the usual testing procedures do not distinguish the two mechanisms. Currently, identification of MRGPRX2 activation and diagnosis of pseudoallergic reactions is generally viewed as a process of exclusion once other non-immune and immune processes, particularly IgE/FcεRI-mediated degranulation of mast cells, are ruled out. This does not take into account that MRGPRX2 signals via β-arrestin, which can be utilized to detect MRGPRX2 activation by employing MRGPRX2 transfected cells to assess MRGPRX2 activation via two pathways, the G-protein-independent β-arrestin pathway and the G-protein-dependent Ca2+ pathway. Testing procedures, interpretations for distinguishing mechanisms, patient diagnosis, agonist identification and drug safety evaluations are addressed.

Exploring the Pathogenesis and Mechanism-Targeted Treatments of Rosacea: Previous Understanding and Updates

Rosacea is a chronic inflammatory skin disease characterized by recurrent erythema, flushing, telangiectasia, papules, pustules, and phymatous changes in the central area of the face. Patients with this condition often experience a significant negative impact on their quality of life, self-esteem, and overall well-being. Despite its prevalence, the pathogenesis of rosacea is not yet fully understood. Recent research advances are reshaping our understanding of the underlying mechanisms of rosacea, and treatment options based on the pathophysiological perspective hold promise to improve patient outcomes and reduce incidence. In this comprehensive review, we investigate the pathogenesis of rosacea in depth, with a focus on emerging and novel mechanisms, and provide an up-to-date overview of therapeutic strategies that target the diverse pathogenic mechanisms of rosacea. Lastly, we discuss potential future research directions aimed at enhancing our understanding of the condition and developing effective treatments.

Analysis of facial vascular pattern characteristics in the Korean population

BACKGROUND

Facial erythema is a common problem among patients visiting dermatologists. However, data on the clinical characteristics of facial erythema in healthy people are lacking. We aimed to compare and analyze the severity and pattern of facial vascularity in healthy subjects based on their age and gender.

MATERIALS AND METHODS

This study included 198 Korean volunteers (126 females and 72 males) with Fitzpatrick skin types II, III, or IV. Fourteen different anatomical areas on the face were divided into facial erythema units. Each unit was scored from one (least erythematous) to five (most erythematous) according to the observed level of erythema on the red images implemented as hemoglobin content. We also evaluated the presence of facial telangiectatic macules.

RESULTS

On average, the perinasal, nasal, and cheek units were the most hypervascular regions. In contrast, the degree of facial erythema was lowest in the labial (perioral), neck, and temporal regions. The average value of erythema was higher in males than in females. Additionally, the severity of erythema tended to increase with age. In both males and females, the number of telangiectatic macules increased with age.

CONCLUSIONS

We analyzed the clinical characteristics of erythema in healthy subjects with Fitzpatrick skin types II, III, or IV in the Korean population. This study is expected to be used to identify the neurovascular pathogenesis of the most common regions of facial dermatosis in the future.

The orchestra of human bacteriome by hormones

Human microbiome interact reciprocally with the host. Recent findings showed the capability of microorganisms to response towards host signaling molecules, such as hormones. Studies confirmed the complex response of bacteria in response to hormones exposure. These hormones impact many aspects on bacteria, such as the growth, metabolism, and virulence. The effects of each hormone seem to be species-specific. The most studied hormones are cathecolamines also known as stress hormones that consists of epinephrine, norepinephrine and dopamine. These hormones affect the growth of bacteria either inhibit or enhance by acting like a siderophore. Epinephrine and norepinephrine have also been reported to activate QseBC, a quorum sensing in Gram-negative bacteria and eventually enhances the virulence of pathogens. Other hormones were also reported to play a role in shaping human microbiome composition and affect their behavior. Considering the complex response of bacteria on hormones, it highlights the necessity to take the impact of hormones on bacteria into account in studying human health in relation to human microbiome.

CGRP physiology, pharmacology, and therapeutic targets: migraine and beyond

Calcitonin gene-related peptide (CGRP) is a neuropeptide with diverse physiological functions. Its two isoforms (α and β) are widely expressed throughout the body in sensory neurons as well as in other cell types, such as motor neurons and neuroendocrine cells. CGRP acts via at least two G protein-coupled receptors that form unusual complexes with receptor activity-modifying proteins. These are the CGRP receptor and the AMY1 receptor; in rodents, additional receptors come into play. Although CGRP is known to produce many effects, the precise molecular identity of the receptor(s) that mediates CGRP effects is seldom clear. Despite the many enigmas still in CGRP biology, therapeutics that target the CGRP axis to treat or prevent migraine are a bench-to-bedside success story. This review provides a contextual background on the regulation and sites of CGRP expression and CGRP receptor pharmacology. The physiological actions of CGRP in the nervous system are discussed, along with updates on CGRP actions in the cardiovascular, pulmonary, gastrointestinal, immune, hematopoietic, and reproductive systems and metabolic effects of CGRP in muscle and adipose tissues. We cover how CGRP in these systems is associated with disease states, most notably migraine. In this context, we discuss how CGRP actions in both the peripheral and central nervous systems provide a basis for therapeutic targeting of CGRP in migraine. Finally, we highlight potentially fertile ground for the development of additional therapeutics and combinatorial strategies that could be designed to modulate CGRP signaling for migraine and other diseases.

Dietary supplementation of n-3 PUFAs ameliorates LL37-induced rosacea-like skin inflammation via inhibition of TLR2/MyD88/NF-κB pathway

Rosacea is a facial chronic inflammatory skin disease with dysfunction of immune and neurovascular system and treatments for rosacea are challenging. N-3 polyunsaturated fatty acids (PUFAs), one of essential fatty acids, are needed for health maintenance and exert anti-inflammation and immunomodulatory effects in a series of cutaneous diseases such as atopic dermatitis and photoaging through dietary supplementation. However, the role of n-3 PUFAs on rosacea remains to be elucidated. In this study, KEGG enrichment analysis and GO analysis indicated that the biological process and signaling pathways, including chemokine signaling pathway, regulated by n-3 PUFAs highly overlapped with those in the pathogenic biological process of rosacea, especially the erythema telangiectasia type. Next, mice were randomized to fed with a customized n-3 PUFAs diet. We showed that n-3 PUFAs ameliorated skin erythema, inhibited dermal inflammatory cell infiltration (mast cells, neutrophils, and CD4 +T cells) and suppressed elevated pro-inflammatory cytokines in LL37-induced rosacea-like mice. Besides, n-3 PUFAs were also verified to repress angiogenesis in LL37-induced mice skin. Further investigation revealed that n-3 PUFAs attenuated LL37-induced inflammation via TLR2/ MyD88/ NF-κB pathway both in mice and in keratinocytes. In conclusion, our findings underscore that dietary supplementation of n-3 PUFAs have the potential to become an efficient and safe clinical therapeutic candidate for rosacea.

Aberrant amino acid metabolism promotes neurovascular reactivity in rosacea

Rosacea is a chronic skin disorder characterized by abnormal neurovascular and inflammatory conditions on the central face. Despite increasing evidence suggesting that rosacea is associated with metabolic disorders, the role of metabolism in rosacea pathogenesis remains unknown. Here, via a targeted metabolomics approach, we characterized significantly altered metabolic signatures in patients with rosacea, especially for amino acid-related metabolic pathways. Among these, glutamic acid and aspartic acid were highlighted and positively correlated with the disease severity in patients with rosacea. We further demonstrated that glutamic acid and aspartic acid can facilitate the development of erythema and telangiectasia, typical features of rosacea, in the skin of mice. Mechanistically, glutamic acid and aspartic acid stimulated the production of vasodilation-related neuropeptides from peripheral neurons and keratinocytes and induced the release of nitric oxide from endothelial cells and keratinocytes. Interestingly, we provided evidence showing that doxycycline can improve the symptoms of patients with rosacea possibly by targeting the amino acid metabolic pathway. These findings reveal that abnormal amino acid metabolism promotes neurovascular reactivity in rosacea and raise the possibility of targeting dysregulated metabolism as a promising strategy for clinical treatment.

Current research and clinical trends in rosacea pathogenesis

Background

Rosacea is a common and complex chronic inflammatory skin disorder, the pathophysiology and etiology of which remain unclear. Recently, significant new insights into rosacea pathogenesis have enriched and reshaped our understanding of the disorder. A systematic analysis based on current studies will facilitate further research on rosacea pathogenesis.

Objective

To establish an international core outcome and knowledge system of rosacea pathogenesis and develop a challenge, trend and hot spot analysis set for research and clinical studies on rosacea using bibliometric analysis and data mining.

Methods

A search of the WoS, and PubMed, MEDLINE, Embase and Cochrane collaboration databases was conducted to perform visual bibliometric and data analysis.

Results

A total of 2,654 studies were used for the visualization and 302 of the 6,769 outcomes for data analysis. It reveals an increased trend line in the field of rosacea, in which its fast-growing pathogenesis attracted attention closely related to risk, comorbidity and therapeutic strategies. The rosacea pathogenesis has undergone the great development on immunology, microorganisms, genes, skin barriers and neurogenetics. The major of studies have focused on immune and microorganisms. And keyword visualization and data analyses demonstrated the cross-talk between cells or each aspect of pathogenesis, such as gene-gene or gene-environment interactions, and neurological mechanisms associated with the rosacea phenotype warrant further research.

Limitations

Inherent limitations of bibliometrics; and reliance on research and retrospective studies.

Conclusions

The understanding of rosacea's pathogenesis has been significantly enhanced with the improved technology and multidisciplinary integration, but high-quality, strong evidence in favor of genomic and neurogenic requires further research combined with a better understanding of risks and comorbidities to guide clinical practice.

Association between frontal fibrosing Alopecia and Rosacea: Results from clinical observational studies and gene expression profiles

Background

In recent years, frontal fibrosing alopecia (FFA), a type of scarring alopecia, has attracted increasing attention. Several studies have reported the frequent occurrence of rosacea in FFA; however, the association between FFA and rosacea and the underlying pathogenesis have not been thoroughly clarified. Thus, this study aimed to quantify these relationships and investigate their shared molecular mechanisms.

Methods

We evaluated the association between FFA and rosacea by analyzing clinical data from nine observational studies. We then analyzed the gene expression profiles of FFA and rosacea. First, differential expression analysis and weighted gene co-expression network analysis were used to identify the common differentially expressed genes (DEGs). Later, we conducted a functional enrichment analysis and protein-protein interaction network and used seven algorithms to identify hub genes. Then, we performed a correlation analysis between the hub genes and the gene set variation analysis scores of common pathways in the gene set enrichment analysis (GSEA). The results were validated using different datasets. Finally, transcription factors were predicted and verified, and CIBERSORT and single-sample GSEA were used to estimate the infiltrating immune cells.

Results

Patients with FFA had significantly higher odds for rosacea (pooled odds ratio [OR], 2.46; 95% confidence interval [CI], 1.78–3.40), and the pooled prevalence of rosacea in patients with FFA was 23% (95% CI, 14–23%). Furthermore, we identified 115 co-DEGs and 13 hub genes (CCR5, CCL19, CD2, CD38, CD83, CXCL8, CXCL9, CXCL10, CXCL11, CXCR4, IRF1, IRF8, and PTPRC). Seven pathways showed a high correlation with these hub genes. In addition, one TF, STAT1, was highly expressed in both diseases, and the results of the immune infiltration analysis indicated the importance of M1 macrophages and effector memory CD8+ T cells.

Conclusion

This study contributes to the understanding of the relationship between FFA and rosacea, and based on the hub genes, we reveal the potential pathologies shared by the two diseases. This finding provides new insights of underlying molecular mechanisms and it may inspire future research on this comorbidity.

A novel multi-layer perceptron model for assessing the diagnostic value of non-invasive imaging instruments for rosacea

Background

Reflectance confocal microscopy (RCM), VISIA, and dermoscopy have emerged as promising tools for objective diagnosis and assessment of rosacea. However, little is known about the diagnostic value of these imaging systems for rosacea.

Objectives

To assess the diagnostic value of RCM, VISIA, and dermoscopy for rosacea by establishing a novel multilayer perceptron (MLP) model.

Methods

A total of 520 patients with rosacea and other facial diseases were included in this study. A total of 474 samples of dermoscopy data, 374 samples of RCM data, 434 samples of VISIA data, and 291 samples containing three data sources were collected. An MLP model was built with the total data to explore the association between the imageological features of each instrument and the probability of rosacea.

Results

Our MLP model revealed that the area under the receiver operating characteristic curve (AUROC) values of RCM, VISIA and dermoscopy for diagnosing rosacea were 0.5233, 0.5646 and 0.7971, respectively. The integration of these three tools with clinical data could further improve the accuracy of the predictive diagnosis to 0.8385. For the imageological features of each tool, abnormalities (hyperkeratosis or parakeratosis) in the stratum corneum were effective variables for excluding rosacea (odds ratio [OR], 0.4333) under RCM. The indicators of rosacea under VISIA included overall severity of erythema, erythema involving the cheek or superciliary arch, visible red blood vessels, and papules (OR = 2.2745, 3.1592, 1.8365, 2.8647, and 1.4260, respectively). The candidate variables of dermoscopy included yellow background, white background, uniform distribution of vessels, branched vessels, and reticular blood vessels (OR = 0.4259, 0.4949, 2.2858, 3.7444, and 2.4576, respectively).

Conclusions

RCM, dermoscopy, and VISIA each can present several imageological features and were of certain value for assisting rosacea diagnosis. The combined analysis of these three tools using our MLP model may be useful for improving the accuracy of diagnosing rosacea.

Roles of calcitonin gene-related peptide in the skin, and other physiological and pathophysiological functions

Skin immunity is regulated by many mediator molecules. One is the neuropeptide calcitonin gene-related peptide (CGRP). CGRP has roles in regulating the function of components of the immune system including T cells, B cells, dendritic cells (DCs), endothelial cells (ECs), and mast cells (MCs).

Herein we discuss actions of CGRP in mediating inflammatory and vascular effects in various cutaneous models and disorders.

•

CGRP can help to recruit immune cells through endothelium-dependent vasodilation.

•

CGRP plays an important role in the pathogenesis of neurogenic inflammation.

•

Functions of many components in the immune system are influenced by CGRP.

•

CGRP regulates various inflammatory processes in human skin by affecting different cell-types.

Role of botulinum toxin A in improving facial erythema and skin quality

Botulinum toxin A (BTX-A) injections have become the most popular noninvasive cosmetic procedures performed worldwide. With growing interest, investigators continue to uncover an expanding array of aesthetic indications for BTX-A. Botulinum toxin A has been used off-label in the management of masseter hypertrophy for facial slimming, platysmal bands, nasal 'bunny' lines, perioral rhytides, gummy smile and scars, to name a few. Interestingly, the injection of multiple microdroplets of dilute BTX-A into the dermis, sometimes referred to as 'microbotox', has been investigated as a tool for facial rejuvenation. A handful of prospective studies and case series have demonstrated the benefit of BTX-A in the treatment of facial erythema and improving skin texture. The aim of this review is to summarize and appraise currently available data on the role of BTX-A in treating facial erythema and skin quality, with a special focus on potential pathophysiologic mechanisms.

Multifaceted MRGPRX2: New insight into the role of mast cells in health and disease

Cutaneous mast cells (MCs) express Mas-related G protein-coupled receptor-X2 (MRGPRX2; mouse ortholog MrgprB2), which is activated by an ever-increasing number of cationic ligands. Antimicrobial host defense peptides (HDPs) generated by keratinocytes contribute to host defense likely by 2 mechanisms, one involving direct killing of microbes and the other via MC activation through MRGPRX2. However, its inappropriate activation may cause pseudoallergy and likely contribute to the pathogenesis of rosacea, atopic dermatitis, allergic contact dermatitis, urticaria, and mastocytosis. Gain- and loss-of-function missense single nucleotide polymorphisms in MRGPRX2 have been identified. The ability of certain ligands to serve as balanced or G protein-biased agonists has been defined. Small-molecule HDP mimetics that display both direct antimicrobial activity and activate MCs via MRGPRX2 have been developed. In addition, antibodies and reagents that modulate MRGPRX2 expression and signaling have been generated. In this article, we provide a comprehensive update on MrgprB2 and MRGPRX2 biology. We propose that harnessing MRGPRX2's host defense function by small-molecule HDP mimetics may provide a novel approach for the treatment of antibiotic-resistant cutaneous infections. In contrast, MRGPRX2-specific antibodies and inhibitors could be used for the modulation of allergic and inflammatory diseases that are mediated via this receptor.

Radiofrequency Irradiation Modulates TRPV1-Related Burning Sensation in Rosacea

Rosacea is a skin inflammatory condition that is accompanied by not only redness and flushing but also unseen symptoms, such as burning, stinging, and itching. TRPV1 expression in UVB-exposed skin can lead to a painful burning sensation. Upregulated TRPV1 expression helps release neuropeptides, including calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide, and vasoactive intestinal peptide, which can activate macrophage and inflammatory molecules. In this study, we found that radiofrequency (RF) irradiation reduced TRPV1 activation and neuropeptide expression in a UVB-exposed in vivo model and UVB- or heat-treated in an in vitro model. RF irradiation attenuated neuropeptide-induced macrophage activation and inflammatory molecule expression. Interestingly, the burning sensation in the skin of UVB-exposed mice and patients with rosacea was significantly decreased by RF irradiation. These results can provide experimental and molecular evidence on the effective use of RF irradiation for the burning sensation in patients with rosacea.

Identification of novel candidate genes in rosacea by bioinformatic methods

BACKGROUND

Rosacea is a chronic inflammatory skin disease whose psychological consequences severely affect patient's quality of life.

OBJECTIVE

To identify candidate genes of rosacea for potential development of new target therapies.

METHODS

Gene Expression Omnibus datasets were retrieved to obtain differentially expressed genes (DEGs) between rosacea patients and healthy controls. Gene ontology (GO) analyses were used to identify functions of candidate genes. Related signaling pathways of DEGs were analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis. Protein-protein interaction (PPI) networks were applied using search tools for the retrieval of interacting genes/proteins and modulations involving PPI networks were evaluated with use of the MCODE app.

RESULTS

Samples from 19 rosacea patients and 10 healthy controls of dataset GSE65914 were enrolled. A total of 215 DEGs, 115 GO terms and 6 KEGG pathways were identified. A total of 182 nodes and 456 edges were enriched in PPI networks. Maximal clusters showed 15 central nodes and 96 edges. The toll-like receptor (TLR) signaling pathway was the most significant pathway detected and 5 DEGs were identified as candidate genes which included TLR2, C-C motif chemokine (CCL) 5, C-X-C motif chemokine ligand (CXCL) 9, CXCL10 and CXCL11. The results were verified in rosacea patients with use of real-time polymerase chain reaction and immunohistochemistry. Cell-type enrichment analysis revealed 8 lymphocytes that were enriched in rosacea patients.

CONCLUSIONS

The results suggest that both innate and adaptive immune responses were involved in the etiology of rosacea. Five DEGs in the TLR signaling pathway may serve as potential therapeutic target genes.

The association of photo-induced collagen degeneration and the development of telangiectasias in rosacea

Rosacea is a chronic, often progressive disorder characterized by facial erythema, telangiectasias, papules, pustules, and/or rhinophyma. In this study, we investigated the tissue structure in rosacea compared to controls. We performed a case-control study between five patients with mild-to-moderate erythematotelangiectatic rosacea (ETR) and five matched controls. Facial biopsy samples from rosacea patients and controls were stained with picrosirius red for collagen and CD31 for microvessel identification. Mean collagen content was significantly greater in control samples (19.603% ±8.821%) compared to rosacea samples (16.812% ± 7.787%, p = 0.030). In contrast, mean microvessel density was significantly higher in rosacea patients (4.775 E-5 ± 1.493 E-5 µm^-3 ) compared to controls (2.559 E-5 ± 8.732 E-6 µm^-3 , p = 0.004). Mean microvessel lumen area was also significantly higher in rosacea patients (491.710 ± 610.188 µm² ) compared to controls (347.879 ± 539.624 µm² , p = 0.003). We identified a correlation between decreased collagen content and increased microvessel size and density in rosacea patients that was not observed in controls. These structural changes to the dermal matrix may contribute to the characteristic vessel growth and dilation in rosacea.

Distinctive clinical and histological characteristics of atrophic and hypertrophic facial photoageing

BACKGROUND

Photoageing describes complex cutaneous changes which occur following chronic exposure to solar ultraviolet radiation (UVR). Amongst White Northern Europeans, facial photoageing appears as distinct clinical phenotypes: 'hypertrophic' photoageing (HP) and 'atrophic' photoageing (AP). Deep, coarse wrinkles predominate in individuals with HP, whereas those with AP have relatively smooth, unwrinkled skin with pronounced telangiectasia. AP individuals have an increased propensity for developing keratinocyte cancers.

OBJECTIVES

To investigate whether histological differences underlie these distinct phenotypes of facial photoageing.

METHODS

Facial skin biopsies were obtained from participants with AP (10 M, 10 F; mean age: 78.7 years) or HP (10 M, 10 F; mean age: 74.5 years) and were assessed histologically and by immunohistochemistry.

RESULTS

Demographic characterization revealed 95% of AP subjects, as compared to 35% with HP, were Fitzpatrick skin type I/II; of these, 50% had a history of one or more keratinocyte cancers. There was no history of keratinocyte cancers in the HP cohort. Analysis of UVR-induced mitochondrial DNA damage confirmed that all volunteers had received similar lifetime cumulative doses of sun exposure. Histologically, male AP had a significantly thicker epidermis than did AP females or those of either sex with HP. HP facial skin exhibited severe solar elastosis, whereas in AP facial skin, solar elastosis was apparent only in females. Loss of papillary dermal fibrillin-rich microfibrils occurred in all HP and AP female subjects, but not in AP males. Furthermore, male AP had a significant reduction in collagen VII at the dermal-epidermal junction than did AP females or those of either sex with HP.

CONCLUSIONS

This study provides further evidence that AP and HP represent distinct clinical and histological entities. Knowledge of these two phenotypes is clinically relevant due to the increased prevalence of keratinocyte cancers in those - particularly males - with the AP phenotype.

Clinicopathological and Immunohistochemical Study of 14 Cases of Morbihan Disease: An Insight Into Its Pathogenesis

INTRODUCTION

Morbihan disease (MORD) is rare with only 45 clear-cut cases previously reported. Histopathologic findings are supposed to be nonspecific. We report 14 patients and review the previous cases.

OBJECTIVES

To characterize the clinicopathologic findings, outcomes, and immunophenotype of MORD.

MATERIAL AND METHODS

Inclusion criteria were a clinical picture of persistent, nonpitting edema affecting the mid and or upper third of the face and histopathological findings fitting previous reports and exclusion of other entities.

RESULTS

The majority of our patients were males (71.5%) with a male/female ratio of 10/4. The mean age when diagnosed was 58.8 years. Eyelids and forehead were the most frequently involved areas. Two of the patients presented previous rosacea. Most constant histopathological findings were lymphatic vessel dilatations in the upper dermis and the presence of mast cells (7.5 in 10 high-power field as a mean). Mild edema was also present in most of the cases. Granulomas were found in 7 of the cases, and immunostaining with CD68 and CD14 only revealed an additional case.

CONCLUSIONS

MORD occurs more in middle-aged males, not associated with rosacea and mostly affects eyelids and forehead. Granulomas are not mandatory for the diagnosis. Histopathology of MORD fits within the spectrum of localized lymphedema.

The Theranostics Role of Mast Cells in the Pathophysiology of Rosacea

Rosacea is a chronic inflammatory cutaneous disorder that adversely affects patient's health and quality of life due to the complex course and the need for repeated treatment. The exact molecular mechanisms of rosacea are unclear. Mast cells are innate immune cells that can be found in virtually all tissues. Recently, increasing evidence has indicated that mast cells have important effects on the pathogenesis of rosacea. In this review article, we describe recent advances of skin mast cells in the development of rosacea. These studies suggested that mast cells can be an important immune cell that connected innate immunity, nerves, and blood vessels in the development of rosacea. Moreover, we review the inhibition of mast cells for the potential treatment of rosacea.

Atrophic and hypertrophic photoaging: Clinical, histologic, and molecular features of 2 distinct phenotypes of photoaged skin

BACKGROUND

Exposure to the sun causes premature skin aging, known as photoaging. Clinical features of photoaging vary widely among individuals. In one form, skin appears thin with telangiectasia, and in another form, skin appears thickened with coarse wrinkles. Etiologic, clinical, and therapeutic distinctions among different forms of photoaging remain largely unknown.

OBJECTIVE

To characterize the clinical, histologic, and molecular features of hypertrophic and atrophic photoaging.

METHODS

In total, 53 individuals were clinically classified as having primarily atrophic or hypertrophic photoaging or neither (controls). Participants' demographic and sun exposure-related lifestyle data were captured by questionnaire. Fifteen clinical features of participants were qualitatively or quantitively scored. Facial biopsies were analyzed for gene expression and histologic characteristics.

RESULTS

Actinic and seborrheic keratosis, telangiectasia, and prior incidence of skin cancers were statistically significantly greater and photoaging scale severity, coarse wrinkles, thickness, and sallowness were significantly reduced in atrophic versus hypertrophic groups. Histology also revealed significantly less elastotic material in atrophic photoaging. Gene expression of matrix metalloproteinases and collagens did not differ between the 2 forms of photoaging.

LIMITATIONS

The study was not designed to identify other possible subtypes of photoaging.

CONCLUSION

Systematic, categorical, and quantitative clinical and histologic assessments distinguish atrophic and hypertrophic photoaging.

Skin neurogenic inflammation

The epidermis closely interacts with nerve endings, and both epidermis and nerves produce substances for mutual sustenance. Neuropeptides, like substance P (SP) and calcitonin gene-related protein (CGRP), are produced by sensory nerves in the dermis; they induce mast cells to release vasoactive amines that facilitate infiltration of neutrophils and T cells. Some receptors are more important than others in the generation of itch. The Mas-related G protein-coupled receptors (Mrgpr) family as well as transient receptor potential ankyrin 1 (TRPA1) and protease activated receptor 2(Par2) have important roles in itch and inflammation. The activation of MrgprX1 degranulates mast cells to communicate with sensory nerve and cutaneous cells for developing neurogenic inflammation. Mrgprs and transient receptor potential vanilloid 4 (TRPV4) are crucial for the generation of skin diseases like rosacea, while SP, CGRP, somatostatin, β-endorphin, vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating polypeptide (PACAP) can modulate the immune system during psoriasis development. The increased level of SP, in atopic dermatitis, induces the release of interferon (IFN)-γ, interleukin (IL)-4, tumor necrosis factor (TNF)-α, and IL-10 from the peripheral blood mononuclear leukocytes. We are finally starting to understand the intricate connections between the skin neurons and resident skin cells and how their interaction can be key to controlling inflammation and from there the pathogenesis of diseases like atopic dermatitis, psoriasis, and rosacea.

Evaluating and Optimizing the Diagnosis of Erythematotelangiectatic Rosacea

Erythematotelangiectatic rosacea is the most prevalent rosacea subtype. Multiple dermatologic conditions may mimic erythematotelangiectatic rosacea. The authors review a comprehensive approach to evaluating subjects with a suspected diagnosis of erythematotelangiectatic rosacea and discuss findings that may warrant further investigation. Differential diagnoses can be narrowed based on the presence of characteristics such as transient erythema, nontransient erythema, and telangiectasias. A thorough history and physical examination are critical in ruling out conditions such as dermatomyositis, lupus erythematosus, atopic dermatitis, and seborrheic dermatitis.

Standard classification and pathophysiology of rosacea: The 2017 update by the National Rosacea Society Expert Committee

In 2002, the National Rosacea Society assembled an expert committee to develop the first standard classification of rosacea. This original classification was intended to be updated as scientific knowledge and clinical experience increased. Over the last 15 years, significant new insights into rosacea's pathogenesis and pathophysiology have emerged, and the disorder is now widely addressed in clinical practice. Growing knowledge of rosacea's pathophysiology has established that a consistent multivariate disease process underlies the various clinical manifestations of this disorder, and the clinical significance of each of these elements is increasing as more is understood. This review proposes an updated standard classification of rosacea that is based on phenotypes linked to our increased understanding of disease pathophysiology. This updated classification is intended to provide clearer parameters to conduct investigations, guide diagnosis, and improve treatment.

Rosacea: Epidemiology, pathogenesis, and treatment

Rosacea is a chronic relapsing inflammatory skin disease with a high prevalence among adults of Northern European heritage with fair skin. Symptoms present in various combinations and severity, often fluctuating between periods of exacerbation and remission. Based on morphological characteristics, rosacea is generally classified into four major subtypes: erythematotelangiectatic, papulopustular, phymatous, and ocular. Diverse environmental and endogenous factors have been shown to stimulate an augmented innate immune response and neurovascular dysregulation; however, rosacea's exact pathogenesis is still unclear. An evidence-based approach is essential in delineating differences between the many available treatments. Because of the diverse presentations of rosacea, approaches to treatment must be individualized based on the disease severity, quality-of-life implications, comorbidities, trigger factors, and the patient's commitment to therapy.

Treatment of erythemato-telangiectatic rosacea with brimonidine alone or combined with vascular laser based on preliminary instrumental evaluation of the vascular component

The purpose of this study is to evaluate the outcome of a series of patients with erythematotelangiectatic rosacea (ETR) affected by persistent erythema and varying degree of telangiectasias being treated with brimonidine alone or combined with a vascular laser based on the type of vascular components preliminarily evaluated by clinical and instrumental observation. Ten patients affected by ETR were enrolled in a pilot, open study. Instrumental evaluation included erythema-directed digital photography by VISIA-CR™ system and X10 dermoscopy. Those patients showing marked background erythema and minimal telangiectasias (group A) were treated with a single application of brimonidine 0.33% gel, while patients showing both marked background erythema and marked telangiectasias (group B) were treated with a session of Nd:YAG laser and reevaluated 1 month later after a single application of brimonidine. An Investigator Global Assessment (IGA) of treatment outcome was performed at the end of treatment in both groups. In group A, 6 h after brimonidine application, a marked reduction of the background erythema was observed in all patients, and IGA was rated as excellent. In group B, 6 h following the application of brimonidine, a marked reduction of the background erythema was observed in all cases, while telangiectasias remained unchanged. A further treatment with brimonidine 1 month after the Nd:YAG laser session determined complete clearing of facial erythema, and IGA was rated as excellent. In conclusion, a preliminary evaluation of the vascular component by erythema-directed digital photography and dermoscopy in ETR may be helpful to select the most appropriate therapeutic strategy.

Inhibition of mast cell infiltration in an LL-37-induced rosacea mouse model using topical brimonidine tartrate 0.33% gel

Brimonidine is a highly selective α2-adrenergic receptor agonist approved by the FDA for the treatment of rosacea. Rosacea is a major clinical disease with vasodilatation and rash on the centre of the face, and that brimonidine as a vasoconstrictor can act as a remedy for rosacea. However, there is no study of how brimonidine has an effect on rosacea-related immune cells or mechanisms in the skin to improve rosacea. In this study, we observed that clinical features of rosacea induced by LL-37 in Balb/c mice were improved after the application of brimonidine gel, and we also showed a marked decrease in the number of inflammatory cells, especially mast cells (MCs) histologically. Furthermore, we confirmed that mRNA levels of MC enzymes increased by LL-37 were reduced by brimonidine gel. To our knowledge, we first found that brimonidine has a mechanism of treating rosacea by reducing the number and mRNA levels of MC-specific enzymes, an important immune cell in the pathogenesis of rosacea.

[Rosacea: New data for better care]

In the last 10 years, numerous studies have been published that throw new light on rosacea, in all areas of the disease. This overview summarises all the key developments, based on the indexed bibliography appearing in Medline between 2007 and 2017. Recent epidemiological data show that the prevalence of the disease is doubtless greater than estimated hitherto (more than 10% of adults in some countries) and that we should not overlook rosacea in subjects with skin phototypes V or VI, a condition that exists on all continents. A new classification of rosacea by phenotype comprising major and minor signs has been put forward; it provides a more rational approach to suitable management based upon symptoms, the severity of which may be graded into 5 classes. The treatments with the best-demonstrated efficacy (updated Cochrane study) are topical metronidazole, azelaic acid and ivermectin, and oral doxycycline; isotretinoin is effective against resistant forms but is off-label. In ocular rosacea, the reference treatment is doxycycline in combination with topical therapy of the eyelids. The physiopathology is complex and involves several factors: vascular (vasodilatation, vascular growth factors), neurovascular (hypersensitivity, neuropathic pain, neuropeptides), infectious (Demodex folliculorum and its microbiota) and inflammatory (abnormal production of pro-inflammatory peptides of the innate immune system). In addition, there is a genetic predisposition as demonstrated by the weight of familial history and comparison of homozygous and heterozygous twins. There is also activation of several genes involved in immunity, inflammation and lipid metabolism; the theory of hydrolipid film anomalies has been posited once more. There has thus been a tremendous leap forward in the field of rosacea research, with therapeutic progress and improved understanding of the underlying mechanisms, which should enable the future development of more targeted treatments as well as global management of this disease, which has major social and emotional consequences on the life of patients.

Pathogenesis and clinical presentation of rosacea as a key for a symptom-oriented therapy

Rosacea is a common chronic inflammatory skin disorder that typically occurs in adults and affects the face. Synonyms of rosacea include "acne rosacea", "couperose" and "facial erythrosis", in German also "Kupferfinne" and "Rotfinne". The disorder is characterised by a chronic and flaring course and is caused by a genetically predisposed, multifactorial process. A higher incidence is seen in people with fair skin and a positive family history. The characteristic rosacea symptoms manifest primarily, but not exclusively centrofacially, with forehead, nose, chin and cheeks significantly affected. Based on the various main symptoms a classification of the individual clinical pictures can be performed. However, a classification often does not reflect the clinical reality, since the various symptoms commonly coexist. The present review provides an introduction on pathogenesis and clinical manifestations of rosacea and prefers a symptom-oriented therapy approach.

Pathogenese und Klinik der Rosazea als Schlüssel für eine symptomorientierte Therapie

Rosazea ist eine häufige chronisch-entzündliche Hauterkrankung, die typischerweise bei Erwachsenen vorkommt und das Gesicht betrifft. Synonyme der Rosazea sind Acne rosacea, Kupferfinne, Rotfinne, Couperose und Rosacea. Die Erkrankung ist durch einen chronischen und schubartigen Verlauf gekennzeichnet und wird durch ein genetisch prädisponiertes, multifaktorielles Geschehen bedingt. Ein vermehrtes Auftreten wird bei hellem Hauttyp und positiver Familienanamnese verzeichnet. Die charakteristischen Rosazea-Symptome manifestieren sich vorwiegend, aber nicht ausschließlich zentrofazial, wobei Stirn, Nase, Kinn und die Wangen maßgeblich betroffen sind. Dabei werden unterschiedliche Hauptsymptome voneinander unterschieden, anhand derer eine Klassifikation der verschiedenen klinischen Bilder vorgenommen werden kann. Eine Klassifizierung wird oftmals jedoch nicht der klinischen Realität gerecht, da die verschiedenen Symptome häufig gemeinsam auftreten. Diese Übersichtarbeit führt in die Pathogenese und Klinik der Rosazea ein und plädiert für einen symptomorientierten Therapieansatz.

Updating the diagnosis, classification and assessment of rosacea: recommendations from the global ROSacea COnsensus (ROSCO) panel

BACKGROUND

Rosacea is currently diagnosed by consensus-defined primary and secondary features and managed by subtype. However, individual features (phenotypes) can span multiple subtypes, which has implications for clinical practice and research. Adopting a phenotype-led approach may facilitate patient-centred management.

OBJECTIVES

To advance clinical practice by obtaining international consensus to establish a phenotype-led rosacea diagnosis and classification scheme with global representation.

METHODS

Seventeen dermatologists and three ophthalmologists used a modified Delphi approach to reach consensus on statements pertaining to critical aspects of rosacea diagnosis, classification and severity evaluation. All voting was electronic and blinded.

RESULTS

Consensus was achieved for transitioning to a phenotype-based approach to rosacea diagnosis and classification. The following two features were independently considered diagnostic for rosacea: (i) persistent, centrofacial erythema associated with periodic intensification; and (ii) phymatous changes. Flushing, telangiectasia, inflammatory lesions and ocular manifestations were not considered to be individually diagnostic. The panel reached agreement on dimensions for phenotype severity measures and established the importance of assessing the patient burden of rosacea.

CONCLUSIONS

The panel recommended an approach for diagnosis and classification of rosacea based on disease phenotype.

Multidisciplinary Consideration of Potential Pathophysiologic Mechanisms of Paradoxical Erythema with Topical Brimonidine Therapy

Rosacea is a chronic inflammatory disease with transient and non-transient redness as key characteristics. Brimonidine is a selective α2-adrenergic receptor (AR) agonist approved for persistent facial erythema of rosacea based on significant efficacy and good safety data. The majority of patients treated with brimonidine report a benefit; however, there have been sporadic reports of worsening erythema after the initial response. A group of dermatologists, receptor physiology, and neuroimmunology scientists met to explore potential mechanisms contributing to side effects as well as differences in efficacy. We propose the following could contribute to erythema after application: (1) local inflammation and perivascular inflammatory cells with abnormally functioning ARs may lead to vasodilatation; (2) abnormal saturation and cells expressing different AR subtypes with varying ligand affinity; (3) barrier dysfunction and increased skin concentrations of brimonidine with increased actions at endothelial and presynaptic receptors, resulting in increased vasodilation; and (4) genetic predisposition and receptor polymorphism(s) leading to different smooth muscle responses. Approximately 80% of patients treated with brimonidine experience a significant improvement without erythema worsening as an adverse event. Attention to optimizing skin barrier function, setting patient expectations, and strategies to minimize potential problems may possibly reduce further the number of patients who experience side effects.

FUNDING

Galderma International S.A.S., Paris, France.

Topical Ivermectin 10 mg/g and Oral Doxycycline 40 mg Modified-Release: Current Evidence on the Complementary Use of Anti-Inflammatory Rosacea Treatments

Rosacea is a common, chronic inflammatory skin disease that can present with a variety of signs and symptoms. The potentially simultaneous occurrence of different signs and symptoms is due to different underlying inflammatory pathways, emphasizing the need for complementary treatment approaches. Topical ivermectin cream (10 mg/g) and systemic, oral anti-inflammatory doxycycline (40 mg modified-release) are both approved for the treatment of papulopustular rosacea (PPR). Whether or not a combined therapeutic approach may be more beneficial than monotherapy for patients with PPR remains to be tested. Here, we summarize underlying inflammatory pathways implicated in rosacea and clarify the impact of these two agents on selective pathways during inflammation, due to specific characteristics of their individual mechanisms of action (MoA). Based on the complementary MoA of doxycycline modified-release and ivermectin, a scientific rationale for a combined therapy targeting inflammatory lesions in rosacea is given. We propose that topical ivermectin cream is a promising new candidate as first-line treatment to target the inflammatory lesions of rosacea, which can be used in combination with systemic doxycycline modified-release to provide an optimal treatment approach considering all inflammatory pathways involved in PPR.

Funding Galderma.