Keratinocyte apoptosis in epidermal remodeling and clearance of psoriasis induced by UV radiation

How Cells Die in Psoriasis?

Psoriasis, a chronic immune-mediated inflammatory skin disorder characterized by keratinocyte hyperproliferation and inflammatory cell infiltration, involves multiple distinct programmed cell death pathways in its pathogenesis. Following the Nomenclature Committee on Cell Death recommendations, we analyzed the current literature examining diverse modes of cellular death in psoriatic lesions, with particular focus on keratinocyte cell death patterns and their molecular signatures. Analysis revealed several distinct cell death mechanisms: autophagy dysfunction through IL-17A pathways, decreased apoptotic activity in lesional skin, medication targeting anoikis in psoriasis, upregulated necroptosis mediated by RIPK1/MLKL signaling, gasdermin-mediated pyroptosis with enhanced IL-1β secretion, coordinated PANoptotic activation through specialized complexes, PARP1-mediated parthanatos promoting cutaneous inflammation, iron-dependent ferroptosis correlating with Th22/Th17 responses, copper-dependent cuproptosis with elevated MTF1/ATP7B/SLC31A1 expression, and NETosis amplifying immune responses through interaction with the Th17 axis. The intricate interplay between these cell death mechanisms has led to the development of targeted therapeutic strategies, including mTOR inhibitors for autophagy modulation, RIPK1 inhibitors for necroptosis, and various approaches targeting ferroptosis and NETosis, providing new directions for more effective psoriasis treatments.

IL-17 Ligand and Receptor Family Members Are Differentially Expressed by Keratinocyte Subpopulations and Modulate Their Differentiation and Inflammatory Phenotype

Psoriasis is a chronic inflammatory skin disease characterized by dysregulation of the interleukin 17 (IL-17) signaling axis. Given that psoriasis development depends on keratinocyte stem cells and early progenitors' sensitivity to differentiation, we analyzed IL-17 ligands and the expression and function of in a novel subset of keratinocyte subpopulations: keratinocyte stem cells (KSC) and early and late Transit Amplifying (ETA or LTA, respectively) cells. We found that all subpopulations expressed all IL-17 variants, predominantly in ETA and LTA. Conversely, IL-17 receptor expression resulted in more heterogeneity, with IL-17RA, -C, and -E being the most differentially regulated. Stimulus with IL-17A, IL-17-F, IL-17-A/F, and IL-17C promotes the upregulation of CXCL1, CXCL8, and DEFB4 mRNAs expression in both KSC and ETA. Moreover, IL-17A and IL-17A/F mainly decrease KSC proliferation and promote cell cycle block. Globally, IL-17A and IL-17A/F modulated the expression of proliferation, differentiation, and psoriasis-associated markers. Furthermore, KSC- and ETA-derived 3D reconstructions displayed increased epidermal thickness and upregulated KRT16 expression after treatment with IL-17A or IL-17A/F. Therefore, our data demonstrated that IL-17 family members perform distinctive functions in a specific keratinocyte subpopulation and define IL-17 signaling as a critical modulator of KSC behavior, proving its role in epidermal homeostasis dysregulation of psoriasis.

Association between sun-protective behaviours and psoriasis in US adults in the National Health and Nutrition Examination Survey, 2009-2014: a cross-sectional study

OBJECTIVE

To evaluate the association between sun-protective behaviours and psoriasis in a nationally representative sample of US adults.

DESIGN

Analysis of cross-sectional data.

SETTING

National Health and Nutrition Examination Survey (NHANES), 2009-2014.

PARTICIPANTS

A total of 9735 participants aged 20-59 years with available data on psoriasis, sun-protective behaviours and covariates were included in the analysis.

OUTCOME MEASURES

Information on sun-protective behaviours (staying in the shade, wearing long sleeves and using sunscreen) and psoriasis was obtained from questionnaires in the NHANES database. Logistic regression models and subgroup analyses were employed to investigate the association between sun-protective behaviours and psoriasis.

RESULTS

After adjusting for sociodemographic variables, body mass index (BMI), alcohol drinking status, smoking status, sun sensitivity and time spent outdoors in the multivariable logistic regression model, moderate wearing of long sleeves was negatively associated with psoriasis (OR, 0.55; 95% CI 0.33 to 0.90, p=0.02), while frequent wearing showed no significant relationship. There was no significant association between staying in the shade and psoriasis, regardless of frequency. Subgroup analyses stratified by age, gender, race/ethnicity and smoking status revealed no significant associations in most groups, but moderate wearing of long sleeves was found to be negatively associated with psoriasis among those aged 20-39 years (OR, 0.42; 95% CI 0.18 to 0.98, p=0.04), among non-Hispanic white individuals (OR, 0.52; 95% CI 0.28 to 0.97, p=0.04) and among non-smokers (OR, 0.49; 95% CI 0.25 to 0.95, p=0.04), as it was among women in terms of overall sun protection (OR, 0.58; 95% CI 0.35 to 0.97, p=0.04). However, among non-Hispanic white individuals (staying in the shade: OR, 1.69; 95% CI 1.00 to 2.84, p=0.049) and former/current smokers (overall: OR, 3.28; 95% CI 1.41 to 7.63, p=0.009), frequent sun protection was positively associated with psoriasis.

CONCLUSIONS

Moderate sun-protective behaviours among US adults were found to be negatively associated with psoriasis. However, among non-Hispanic white individuals and former/current smokers, frequent sun protection was positively associated with psoriasis. Future studies with rigorous study design could further explore and validate the potential reasons for these associations to better inform evidence-based behavioural recommendations that protect human health.

Geriatric Psoriasis: Evaluation of Clinical Features, Disease Course, and Treatment Modalities of Patients from a Tertiary Care Hospital

INTRODUCTION

Psoriasis is an inflammatory skin disease characterized by erythematous, scaly, pruritic plaques on the extensor areas of the extremities. It is one of the most common dermatological diseases in the geriatric population.

OBJECTIVE

The aim of this investigation was to evaluate the demographic data, clinical characteristics, and treatment responses of the geriatric population (≥65 years) with psoriasis at our hospital.

METHODS

In this study, we examined 160 geriatric patients diagnosed with psoriasis. We evaluated patients in two groups: early onset (EaO) (<60 years) and elderly onset (EO) (≥60 years).

RESULTS

In our study, 53.8% of the patients were male, the average age was 68.7 years, and 65% of the patients were considered EaO. Knee and elbow lesions were detected more frequently at the beginning and during the disease in the EaO group; 44.4% of patients had nail psoriasis, while 20.6% had psoriatic arthritis. Nail involvement (P = 0.17) and the presence of psoriatic arthritis (P = 0.035) were more common in the EaO group. Erythrodermic psoriasis was more common in the EaO group, but it was not statistically significant (P = 0.097). It was observed that the disease course of psoriasis was slower in the EaO group compared to the EO group (P = 0.001). Systemic treatment was predominantly initiated as the first treatment agent in the EO group (P = 0.006). Patients in the EaO group received more cyclosporine treatment than the others (P = 0.004).

CONCLUSIONS

The geriatric population is associated with multiple comorbidities and polypharmacy, highlighting the importance of evaluating patients' medications and comorbidities when selecting a treatment agent for psoriasis.

Serum dsDNA is environmentally contingent

Psoriasis is a recurrent autoimmune disease characterized by seasonal and latitudinal variations. Double-stranded DNA (dsDNA) is a crucial component of nucleic acids and nucleosomes that provoke innate immune responses. Given the potential influence of climate on immunity and the development of autoimmune diseases, a comprehensive quantitative analysis of dsDNA levels in the population is warranted. In this case-control study conducted from 2016 to 2020, 10,110 psoriasis patients and matched controls from 12 regions in China were included. This study examined variations in serum dsDNA levels based on season and latitude. The results revealed significant associations between geographical location, climatic conditions, and season with serum dsDNA concentration. Individuals residing in Northern China exhibited significantly higher serum dsDNA levels compared to those in the South (1.00 vs. 0.96 ng/ml), and those in medium latitude regions had higher levels than their counterparts in areas with extreme latitudes (0.98 vs. 0.96 ng/ml). Furthermore, individuals in regions with low to medium ultraviolet exposure demonstrated higher serum dsDNA concentrations than those in areas with high ultraviolet levels (1.03 vs. 0.93 ng/ml), and individuals in winter showed higher levels than those in summer (1.03 vs. 0.92 ng/ml). Factors such as sex, UV index, humidity, and sunshine duration were inversely related to serum dsDNA levels, while age and daylight hours showed a positive association. These findings suggest that meteorological and climatic factors play a role in influencing serum dsDNA levels.

Plasma levels and diagnostic utility of VEGF, MMP-9 and TIMP-2 in the diagnosis of psoriasis forms

Psoriasis pathogenisis remain unknown despite the fact that it is considered as the most common autoimmune skin disease. We raised the hypothesis whether the selected biomarkers in this study provide actual evidence of psoriasis presence and severity. We aim in a first level to study serum level of pro-angiogenic marker VEGF variation and its correlation with MMP-9 and its specific inhibitor TIMP-2 in psoriatic patients serum. The study included 115 psoriatic patients and 51 controls. The biological parameters were measured by ELISA methods. Logistic regression analysis showed that VEGF, MMP-9, and inflammation Z-score are associated with psoriasis. ROC analysis showed that VEGF has low discriminant power for PsVG, However TIMP-2 and inflammation Z-scorewell discriminate this variant of psoriasis. The combined analysis of VEGF-TIMP-2 resulted in a significant increase in discriminant power for PsVG. Increase inflammatory phase may be reflecting the tissue destruction byMMP-9, emphasizing the deleterious expanse and the architectural changes of the skin which are more severe in PsP.

Gasdermin E promotes translocation of p65 and c-jun into nucleus in keratinocytes for progression of psoriatic skin inflammation

Gasdermin E (GSDME) has recently been identified as a critical executioner to mediate pyroptosis. While epidermal keratinocytes can initiate GSDME-mediated pyroptosis, the role of keratinocyte GSDME in psoriatic dermatitis remains poorly characterized. Through analysis of GEO datasets, we found elevated GSDME levels in psoriatic lesional skin. Additionally, GSDME levels correlated with both psoriasis severity and response to biologics treatments. Single-cell RNA sequencing (scRNA-seq) from a GEO dataset revealed GSDME upregulation in keratinocytes of psoriasis patients. In the imiquimod (IMQ)-induced psoriasis-like dermatitis mouse model, both full-length and cleaved forms of caspase-3 and GSDME were elevated in the epidermis. Abnormal proliferation and differentiation of keratinocytes and dermatitis were attenuated in Gsdme-/- mice and keratinocyte-specific Gsdme conditional knockout mice after IMQ stimulation. Exposure of keratinocytes to mixed cytokines (M5), mimicking psoriatic conditions, led to GSDME cleavage. Moreover, the interaction between GSDME-FL and p65 or c-jun was significantly increased after M5 stimulation. GSDME knockdown inhibited nuclear translocation of p65 and c-jun and decreased upregulation of psoriatic inflammatory mediators such as IL1β, CCL20, CXCL1, CXCL8, S100A8, and S100A9 in M5-challenged keratinocytes. In conclusion, GSDME in keratinocytes contributes to the pathogenesis and progression of psoriasis, potentially in a pyroptosis-independent manner by interacting and promoting translocation of p65 and c-jun. These findings suggest that keratinocyte GSDME could serve as a potential therapeutic target for psoriasis treatment.

Phototherapy Restores Deficient Type I IFN Production and Enhances Antitumor Responses in Mycosis Fungoides

Transcriptional profiling demonstrated markedly reduced type I IFN gene expression in untreated mycosis fungoides (MF) skin lesions compared with that in healthy skin. Type I IFN expression in MF correlated with antigen-presenting cell-associated IRF5 before psoralen plus UVA therapy and epithelial ULBP2 after therapy, suggesting an enhancement of epithelial type I IFN. Immunostains confirmed reduced baseline type I IFN production in MF and increased levels after psoralen plus UVA treatment in responding patients. Effective tumor clearance was associated with increased type I IFN expression, enhanced recruitment of CD8+ T cells into skin lesions, and expression of genes associated with antigen-specific T-cell activation. IFNk, a keratinocyte-derived inducer of type I IFNs, was increased by psoralen plus UVA therapy and expression correlated with upregulation of other type I IFNs. In vitro, deletion of keratinocyte IFNk decreased baseline and UVA-induced expression of type I IFN and IFN response genes. In summary, we find a baseline deficit in type I IFN production in MF that is restored by psoralen plus UVA therapy and correlates with enhanced antitumor responses. This may explain why MF generally develops in sun-protected skin and suggests that drugs that increase epithelial type I IFNs, including topical MEK and EGFR inhibitors, may be effective therapies for MF.

Roles and mechanisms of umbilical cord mesenchymal stem cells in the treatment of diabetic foot: A review of preclinical and clinical studies

AIMS

Growing preclinical and clinical evidence has suggested the potential method of umbilical cord mesenchymal stem cell (UCMSC) therapy for diabetic foot. Thus, the authors provided an outline of the application of UCMSCs in the treatment of diabetic foot and further summarized the roles and mechanisms of this therapy.

DATA SYNTHESIS

With no time limitations, the authors searched the Web of Science, Cochrane Central Register of Controlled Trials, and PubMed (MEDLINE) databases. 14 studies were included, including 9 preclinical experiments and 5 clinical trials (3 RCTs and 2 single-arm trials).

CONCLUSIONS

The UCMSCs are of great efficacy and safety, and function mainly by reducing inflammation, regulating immunity, promoting growth factors, and enhancing the functions of vascular endothelial cells, fibroblasts, and keratinocytes. As a result, ulcer healing-related biological processes ensue, which finally lead to diabetic foot ulcer healing and clinical symptom improvement. UCMSC treatment enhances diabetic foot ulcer healing and has a safety profile. They function mainly by modulating immunity, promoting growth factor secretion, and enhancing cellular functions. More well-designed preclinical and clinical studies are needed to provide the most optimal protocol, the comprehensive molecular mechanisms, as well as to further evaluate the efficiency and safety profile of UCMSC treatment in diabetic foot patients.

Depletion of G9A attenuates imiquimod-induced psoriatic dermatitis via targeting EDAR-NF-κB signaling in keratinocyte

Psoriasis is a common and recurrent inflammatory skin disease characterized by inflammatory cells infiltration of the dermis and excessive proliferation, reduced apoptosis, and abnormal keratosis of the epidermis. In this study, we found that G9A, an important methyltransferase that mainly mediates the mono-methylation (me1) and di-methylation (me2) of histone 3 lysine 9 (H3K9), is highly expressed in lesions of patients with psoriasis and imiquimod (IMQ)-induced psoriasis-like mouse model. Previous studies have shown that G9A is involved in the pathogenesis of various tumors by regulating apoptosis, proliferation, differentiation, and invasion. However, the role of G9A in skin inflammatory diseases such as psoriasis remains unclear. Our data so far suggest that topical administration of G9A inhibitor BIX01294 as well as keratinocyte-specific deletion of G9A greatly alleviated IMQ-induced psoriatic alterations in mice for the first time. Mechanistically, the loss function of G9A causes the downregulation of Ectodysplasin A receptor (EDAR), consequently inhibiting the activation of NF-κB pathway, resulting in impaired proliferation and increased apoptosis of keratinocytes, therefore ameliorating the psoriatic dermatitis induced by IMQ. In total, we show that inhibition of G9A improves psoriatic-like dermatitis mainly by regulating cell proliferation and apoptosis rather than inflammatory processes, and that this molecule may be considered as a potential therapeutic target for keratinocyte hyperproliferative diseases such as psoriasis.

Individualised computational modelling of immune mediated disease onset, flare and clearance in psoriasis

Despite increased understanding about psoriasis pathophysiology, currently there is a lack of predictive computational models. We developed a personalisable ordinary differential equations model of human epidermis and psoriasis that incorporates immune cells and cytokine stimuli to regulate the transition between two stable steady states of clinically healthy (non-lesional) and disease (lesional psoriasis, plaque) skin. In line with experimental data, an immune stimulus initiated transition from healthy skin to psoriasis and apoptosis of immune and epidermal cells induced by UVB phototherapy returned the epidermis back to the healthy state. Notably, our model was able to distinguish disease flares. The flexibility of our model permitted the development of a patient-specific “UVB sensitivity” parameter that reflected subject-specific sensitivity to apoptosis and enabled simulation of individual patients’ clinical response trajectory. In a prospective clinical study of 94 patients, serial individual UVB doses and clinical response (Psoriasis Area Severity Index) values collected over the first three weeks of UVB therapy informed estimation of the “UVB sensitivity” parameter and the prediction of individual patient outcome at the end of phototherapy. An important advance of our model is its potential for direct clinical application through early assessment of response to UVB therapy, and for individualised optimisation of phototherapy regimes to improve clinical outcome. Additionally by incorporating the complex interaction of immune cells and epidermal keratinocytes, our model provides a basis to study and predict outcomes to biologic therapies in psoriasis.

We present a new computer model for psoriasis, an immune-mediated disabling skin disease which presents with red, raised scaly plaques that can appear over the whole body. Psoriasis affects millions of people in the UK alone and causes significant impairment to quality of life, and currently has no cure. Only a few treatments (including UVB phototherapy) can induce temporary remission. Despite our increased understanding about psoriasis, treatments are still given on a ‘trial and error’ basis and there are no reliable computer models that can a) elucidate the mechanisms behind psoriasis onset or flare and b) predict a patient’s response to a course of treatment (e.g., phototherapy) and the likelihood of inducing a period of remission. Our computer model addresses both these needs. First, it explicitly describes the interaction between the immune system and skin cells. Second, our model captures response to therapy at the individual patient level and enables personalised prediction of clinical outcomes. Notably, our model also supports prediction of amending individual UVB phototherapy regimes based on the patient’s initial response that include for example personalised delivery schedules (i.e., 3x weekly vs. 5x weekly phototherapy). Therefore, our work is a crucial step towards precision medicine for psoriasis treatment.

Transcriptome profiling in psoriasis: NB-UVB treatment-associated transcriptional changes and modulation of autoinflammation in perilesional skin in early-phase disease

BACKGROUND

Psoriasis is a chronic inflammatory skin condition. It is widely treated with phototherapy using narrowband ultraviolet B (NB-UVB). The therapeutic mechanisms of NB-UVB, however, remain unclear, particularly in the early phases of the disease.

OBJECTIVE

To investigate the mechanisms underlying the effects of NB-UVB on psoriasis in a model of perilesional psoriasis.

METHODS

Psoriatic patients that received NB-UVB treatment and were evaluated with the psoriasis area and severity index were included in the study. Skin biopsies obtained before and after treatment were subjected to RNA sequencing (RNA-seq) and Ingenuity Pathway Analyses for genome-wide transcriptome profiling to gain further insights into the signaling pathways underlying the improvement of psoriasis with therapeutic intervention.

RESULTS

Our findings revealed that NB-UVB treatment may exert its effects by suppressing nuclear factor kappa B, which leads to upregulation of the sirtuin signaling pathway, as well as by decreasing the function of major upstream regulators associated with proinflammatory and inflammatory cytokines, which blocks the expression of downstream toll-like receptors. Psoriasis improvement after NB-UVB treatment was associated with decreased expression of NFKBIZ, SERPINB4, ATG13, and CTSS and increased expression of SKP1 gene. Our results also highlighted the expression of proposed genes associated with the modulation of autoinflammation.

CONCLUSIONS

To the best of our knowledge, this is the first study to apply advanced molecular techniques to explore the effects of phototherapy on psoriasis in the early-phase, providing new insights into the disease pathogenesis and novel genetic information for the development of new therapeutic modalities and potential treatment targets.

Climatotherapy at the Dead Sea for psoriasis is a highly effective anti-inflammatory treatment in the short term; an immunohistochemical study

Climatotherapy is a well‐described treatment of psoriasis. Dead Sea climatotherapy (DSC) in Israel consists of intensive sun and Dead Sea bathing and is very effective in improving clinical and patient‐reported outcomes. However, the effect of DSC has not been widely studied. We aimed to investigate the effect of DSC on psoriasis skin using quantitative immunohistochemistry techniques and analysis of blood samples. Skin punch biopsies from 18 psoriasis patients from a previous cohort study were used. Biopsies were obtained from non‐lesional skin and from a psoriasis target lesion at baseline. A biopsy was acquired from the target lesion after DSC. Among patients who achieved complete visual clearance, a biopsy was also obtained at relapse. Blood samples were obtained at the same time points. We performed haematoxylin and eosin staining and quantitative immunohistochemical analysis of CD3, CD4, CD8, CD11c, CD103, CD163, CD207, forkhead box P3, Ki67 and myeloperoxidase. We performed blood tests of cholesterol, c‐reactive protein, glucose, haemoglobin A1c and triglycerides. All skin biomarkers except for CD207 were decreased after DSC. At relapse, none of the biomarkers were significantly different from the baseline lesional measurements. Total CD207 staining correlated with psoriasis area and severity index at baseline while CD163 staining correlated with psoriasis area and severity index at EOT. No changes were observed in selected blood tests during the study. Consistent with clinical results, DSC is highly effective in the short term almost normalising all investigated biomarkers. However, at relapse, biomarkers were upregulated to the baseline level.

An overview of the efficacy of phototherapy in oncodermatology

BACKGROUND

Cutaneous adverse events (AEs) following cancer immunotherapy, targeted therapy, and chemotherapy have been well-documented in the literature. A number of case reports have identified phototherapy, a form of light therapy that mimics sunlight exposure, as a noninvasive treatment modality for these cutaneous toxicities. By inducing local suppression of the immune system, phototherapy is a skin-directed treatment with minimal effect on tumor response. Phototherapy may therefore be a viable treatment option for cutaneous AEs from cancer therapies.

METHODS

We reviewed the literature for patients treated with phototherapy for cutaneous AEs following cancer immunotherapy, targeted therapy, or chemotherapy. We also included three previously unpublished cases from our own institution.

RESULTS

We identified 24 patients (80% male, mean age 67 years, range 49-75 years). Patients received the following phototherapy types: NB-UVB (n = 17), PUVA (n = 6), or PDT (n = 1). A topical steroid was used in conjunction with phototherapy in seven patients. At phototherapy onset, cancer treatment was either continued, temporarily discontinued, or discontinued (n = 9, 6, 7, respectively; in two cases, the cancer treatment course was unknown). Improvement of cutaneous AEs was observed in 96% of patients.

CONCLUSIONS

Phototherapy resulted in full or partial improvement in all but one patient. A topical steroid was used in nearly a third of patients, suggesting some oncodermatologists co-administer topicals to further boost response. Continuation of cancer therapy in the majority of patients highlights an additional advantage of phototherapy. We believe phototherapy may be an effective adjunctive treatment to topical steroids when treating these cutaneous toxicities.

Building vs. Rebuilding Epidermis: Comparison Embryonic Development and Adult Wound Repair

Wound repair is essential to restore tissue function through the rebuilding of pre-existing structures. The repair process involves the re-formation of tissue, which was originally generated by embryonic development, with as similar a structure as possible. Therefore, these two processes share many similarities in terms of creating tissue architecture. However, fundamental differences still exist, such as differences in the cellular components, the status of neighboring tissues, and the surrounding environment. Recent advances in single-cell transcriptomics, in vivo lineage tracing, and intravital imaging revealed subpopulations, long-term cell fates, and dynamic cellular behaviors in live animals that were not detectable previously. This review highlights similarities and differences between adult wound repair and embryonic tissue development with a particular emphasis on the epidermis of the skin.

High-Throughput RNA Sequencing Reveals the Effect of NB-UVB Phototherapy on Major Inflammatory Molecules of Lesional Psoriasis

OBJECTIVE

To identify the narrowband ultraviolet B (NB-UVB)-induced molecular mechanisms that may account for their anti-inflammatory efficacy, gene expression and transcriptome profiling, which were performed using advanced molecular techniques.

METHODS

This research was conducted on patients with moderate-to-severe plaque-type psoriasis who received NB-UVB treatment. RNA sequencing (RNA-Seq) was conducted to assay the transcriptomes and identify the differentially expressed transcripts that had been enriched during the major pathway analysis.

RESULTS

Clinical improvement of psoriasis by NB-UVB therapy is linked to the suppression of the "immunological signaling pathways" and "cell cycle regulatory, growth and proliferation pathways" which are critical to the pathogenesis of the disease. In addition, these results were further substantiated by demonstrating that NB-UVB therapy has a significant effect on keratinocyte differentiation and affects the regulation of genes and inflammatory mediators that are related to cell proliferation and apoptosis. Moreover, NB-UVB phototherapy is also involved with the downregulation of toll-like receptors signaling in lesional psoriasis.

CONCLUSION

NB-UVB is an effective treatment for psoriasis. Our study supports the conclusion that the clinical effectiveness of NB-UVB therapy is based on the suppression of a broad range of inflammatory signaling pathways, gene expression of inflammatory cytokines and increased expressions of anti-inflammatory signaling pathways in psoriatic skin. This is the first study that applied advanced molecular techniques to investigate phototherapy as a new key to unlock genetic knowledge and create novel information. Ultimately, the goal is to increase medical knowledge and improve the patient care of psoriasis.

Recent advances on endogenous gasotransmitters in inflammatory dermatological disorders

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Endogenous gasotransmitters nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H₂S), and potential candidates sulfur dioxide (SO₂), methane (CH₄), hydrogen gas (H₂), ammonia (NH₃) and carbon dioxide (CO₂), are generated within the human body.

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Endogenous and potential gasotransmitters regulate inflammation, vasodilation, and oxidation in inflammatory dermatological disorders.

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Endogenous and potential gasotransmitters play potential roles in psoriasis, atopic dermatitis, acne, and chronic skin ulcers.

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Further research should explore the function of these gases and gas donors and inhibitors in inflammatory dermatological disorders.

Background

Endogenous gasotransmitters are small gaseous mediators that can be generated endogenously by mammalian organisms. The dysregulation of the gasotransmitter system is associated with numerous disorders ranging from inflammatory diseases to cancers. However, the relevance of these endogenous gasotransmitters, prodrug donors and inhibitors in inflammatory dermatological disorders has not yet been thoroughly reviewed and discussed.

Aim of review

This review discusses the recent progress and will provide perspectives on endogenous gasotransmitters in the context of inflammatory dermatological disorders.

Key scientific concepts of review

Endogenous gasotransmitters nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H₂S) are signaling molecules that regulate several physiological and pathological processes. In addition, sulfur dioxide (SO₂), methane (CH₄), hydrogen gas (H₂), ammonia (NH₃), and carbon dioxide (CO₂) can also be generated endogenously and may take part in physiological and pathological processes. These signaling molecules regulate inflammation, vasodilation, and oxidative stress, offering therapeutic potential and attracting interest in the field of inflammatory dermatological disorders including psoriasis, atopic dermatitis, acne, rosacea, and chronic skin ulcers. The development of effective gas donors and inhibitors is a promising alternative to treat inflammatory dermatological disorders with controllable and precise delivery in the future.

The use of psoriasis biomarkers, including trajectory of clinical response, to predict clearance and remission duration to UVB phototherapy

BACKGROUND

Remission duration and treatment response following phototherapy for psoriasis are highly variable and factors influencing these are poorly understood.

OBJECTIVES

Our primary outcome was to investigate whether selected clinical/serum biomarkers were associated with remission duration, and secondly with psoriasis clearance at the end of phototherapy. In addition, we looked at whether early trajectory of UVB clearance was associated with final clearance outcome.

METHODS

We performed a prospective cohort study of 100 psoriasis patients, routinely prescribed Narrowband UVB and measured selected clinical and biochemical biomarkers, including weekly PASI (psoriasis area and severity index) scores. Patients were followed up for 18 months.

RESULTS

The median time to relapse was 6 months (95% CI 5-18) if PASI90 was achieved, and 4 months (95% CI 3-9) if less than PASI90 was achieved. Achieving PASI100 did not result in prolonged remission. On UVB completion, the median final PASI (n = 96) was 1.0 (IQR 0.5, 1.6) with 78 (81%) achieving PASI75 and 39 (41%) achieving PASI90. Improved PASI90 response was significantly associated with lower BMI, higher baseline PASI, non-smoking status and lower cumulative NbUVB. Serum levels of C-reactive protein (CRP) and vitamin D were not associated with clearance or remission duration. Early treatment response from weeks 2-3 was predictive of final outcome. For example, achieving PASI30 at week 3 was significantly associated with PASI90 at the end of the course [36/77 (51%) vs. 2/24 (8%), P < 0.001].

CONCLUSIONS

Raised BMI and positive smoking status predicted poorer phototherapy response. For the first time, we have shown that PASI clearance trajectory over the first 2-3 weeks of UVB, can predict psoriasis clearance. This is an important new step towards developing psoriasis personalized prescribing, which can now be formally tested in clinical trials. These simple clinical measures can be used to inform patient treatment expectations; allowing treatment modifications and/or switching to alternative therapies.

Sortilin regulates keratinocyte proliferation and apoptosis through the PI3K-AKT signaling pathway

Sortilin is found to regulate proliferation and death of different cells, while its role in regulating keratinocyte proliferation and apoptosis is still unknown. In this study, we found that sortilin levels significantly increased in psoriasis patients, and sortilin suppression eliminated the proliferation of HaCaT cells induced by M5 cocktail solution and enhanced the levels of cleaved caspase 3 protein and the Bax/Bcl-2 ratio; however, levels of p-PI3K and p-AKT were decreased. In addition, sortilin silencing remitted the characteristic changes associated with psoriasis-like skin lesions. In summary, suppressed sortilin expression helped inhibit keratinocyte proliferation in HaCaT cells by inactivating PI3K/AKT signaling, which provides a new target for the therapy of psoriasis.

Seasonal Variation of Psoriasis and Its Impact in the Therapeutic Management: A Retrospective Study on Chinese Patients

Background

The seasonal patterns of psoriasis have been observed in previous studies. However, no published data indicated the risk factors associated with the seasonal variation.

Purpose

This study aimed to investigate potentially related factors associated with seasonal pattern of psoriasis and provide possible implications for alleviating psoriasis in clinical practice.

Patients and Methods

The retrospective study was conducted in Chinese patients with psoriasis. Demographic and clinical information were collected. Multivariable logistic regression analyses (calculating adjusted odds ratios [AORs]) were used to analyze data.

Results

We continually enrolled 2270 patients (1496 males and 774 females) with psoriasis based on inclusion criteria. Disease duration (AOR=1.06, 95% CI: 1.05–1.07), hyperlipidemia (AOR=1.77, 95% CI: 1.06–2.98) and smoking (AOR=1.40, 95% CI: 1.17–1.68) were significantly associated with severe psoriasis in autumn/winter. Age (AOR=0.98, 95% CI:0.97–0.99) and occupations with more sunlight exposure (AOR=0.78, 95% CI: 0.61–0.99) were negatively associated with the seasonal aggravation. Subgroup analysis showed that occupations with more sunlight exposure (AOR=0.64, 95% CI: 0.43–0.94) were protective factors only in late-onset psoriasis but not early-onset, while smoking (AOR=1.39, 95% CI: 1.11–1.74) was risk factor in the early-onset psoriasis.

Conclusion

Psoriatic patients who had occupation with more sunlight exposure were less likely to report aggravation of psoriasis in autumn/winter. On the contrary, smoking and hyperlipidemia were positively associated with the seasonal aggravation. Additional prospective study is needed to identify the causality.

Therapeutic wavelengths of ultraviolet B radiation activate apoptotic, circadian rhythm, redox signalling and key canonical pathways in psoriatic epidermis

Ultraviolet B radiation (UVB) exerts pleiotropic effects on human skin. DNA damage response and repair pathways are activated by UVB; if damage cannot be repaired, apoptosis ensues. Although cumulative UVB exposure predisposes to skin cancer, UVB phototherapy is widely used as an effective treatment for psoriasis. Previous studies defined the therapeutic action spectrum of UVB and showed that psoriasis is resistant to apoptosis. This study aimed to investigate early molecular responses within psoriasis plaques following irradiation with single equi-erythemogenic doses of clinically-effective (311 nm, narrow-band) compared to clinically-ineffective (290 nm) UVB. Forty-eight micro-dissected epidermal samples from 20 psoriatic patients were analyzed using microarrays. Our bioinformatic analysis compared gene expression between 311 nm irradiated, 290 nm irradiated and control psoriasis epidermis to specifically identify 311 nm UVB differentially expressed genes (DEGs) and their upstream regulatory pathways. Key DEGs and pathways were validated by immunohistochemical analysis. There was a dynamic induction and repression of 311 nm UVB DEGs between 6 h and 18 h, only a limited number of DEGs maintained their designated expression status between time-points. Key disease and function pathways included apoptosis, cell death, cell migration and leucocyte chemotaxis. DNA damage response pathways, NRF2-mediated oxidative stress response and P53 signalling were key nodes, interconnecting apoptosis and cell cycle arrest. Interferon signalling, dendritic cell maturation, granulocyte adhesion and atherosclerotic pathways were also differentially regulated. Consistent with these findings, top transcriptional regulators of 311 nm UVB DEGs related to: a) apoptosis, DNA damage response and cell cycle control; b) innate/acquired immune regulation and inflammation; c) hypoxia/redox response and angiogenesis; d) circadian rhythmicity; f) EGR/AP1 signalling and keratinocyte differentiation; and g) mitochondrial biogenesis. This research provides important insights into the molecular targets of 311 nm UVB, underscoring key roles for apoptosis and cell death. These and the other key pathways delineated may be central to the therapeutic effects of 311 nm in psoriasis.

The Differential Effect of Cannabidiol on the Composition and Physicochemical Properties of Keratinocyte and Fibroblast Membranes from Psoriatic Patients and Healthy People

The development of psoriasis is accompanied by oxidative stress, which can modify the components of skin cells. Therefore, the aim of this study was to evaluate the effect of cannabidiol (CBD), an antioxidant and anti-inflammatory phytocannabinoid, on the composition and physicochemical properties of the membranes of healthy and psoriatic keratinocytes and fibroblasts exposed to ultraviolet A (UVA) and ultraviolet B (UVB) radiation. In psoriasis-altered cells, decreased levels of the main groups of phospholipids and increased levels of sialic acid and malondialdehyde (MDA), a lipid peroxidation product, as well as negative charge of cell membranes compared to non-diseased cells, were found. On the other hand, UVA/B radiation increased the levels of phospholipids and MDA in both groups of cells. Moreover, psoriatic cells were characterized by lower levels of sialic acid and negative charge of cell membranes, while non-diseased cells showed the opposite response. The CBD treatment intensified some of the changes (phospholipid content and membrane charge) caused by the radiation of psoriatic cells, while it prevented these changes in the cells of healthy people. The results of this study indicate that CBD can prevent structural and functional changes to the membranes of healthy skin cells during phototherapy for psoriasis.

Role of subnetworks mediated by [Formula: see text], IL-23/IL-17 and IL-15 in a network involved in the pathogenesis of psoriasis

Psoriasis is a chronic inflammatory skin disease clinically characterized by the appearance of red colored, well-demarcated plaques with thickened skin and with silvery scales. Recent studies have established the involvement of a complex signalling network of interactions between cytokines, immune cells and skin cells called keratinocytes. Keratinocytes form the cells of the outermost layer of the skin (epidermis). Visible plaques in psoriasis are developed due to the fast proliferation and unusual differentiation of keratinocyte cells. Despite that, the exact mechanism of the appearance of these plaques in the cytokine-immune cell network is not clear. A mathematical model embodying interactions between key immune cells believed to be involved in psoriasis, keratinocytes and relevant cytokines has been developed. The complex network formed of these interactions poses several challenges. Here, we choose to study subnetworks of this complex network and initially focus on interactions involving [Formula: see text], IL-23/IL-17, and IL-15. These are chosen based on known evidence of their therapeutic efficacy. In addition, we explore the role of IL-15 in the pathogenesis of psoriasis and its potential as a future drug target for a novel treatment option. We perform steady state analyses for these subnetworks and demonstrate that the interactions between cells, driven by cytokines could cause the emergence of a psoriasis state (hyper-proliferation of keratinocytes) when levels of [Formula: see text], IL-23/IL-17 or IL-15 are increased. The model results explain and support the clinical potentiality of anti-cytokine treatments. Interestingly, our results suggest different dynamic scenarios underpin the pathogenesis of psoriasis, depending upon the dominant cytokines of subnetworks. We observed that the increase in the level of IL-23/IL-17 and IL-15 could lead to psoriasis via a bistable route, whereas an increase in the level of [Formula: see text] would lead to a monotonic and gradual disease progression. Further, we demonstrate how this insight, bistability, could be exploited to improve the current therapies and develop novel treatment strategies for psoriasis.

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Blood Metagenome in Health and Psoriasis

A survey and analytical assessment of the results of fundamental works on studying blood metagenome (set of all non-human DNA) is carried out. All works on determining bacterial DNA concentration in the whole blood of healthy people are reviewed. Detailed comparison of characteristics of 16S rRNA test (hereinafter 16S-test) and whole metagenome sequencing test (hereinafter WMS-test) is carried out and published in Supplement S1. One of main goals of this review is to identify the drawbacks and mistakes which the studied works contain, particularly to emphasize the crucial importance of determining total concentration of bacterial DNA for comparing patients' metagenomes with those of healthy people as well as for comparing patients' metagenomes with each other. Controlling the level and composition of contamination is equally important. The absence of high-quality contamination control at each step (or at certain steps) of the research significantly reduces the reliability of achieved results. The given review is the first attempt to analyze and systematize the results of blood metagenome studies, whose number has increased considerably in the last few years. The review has been carried out as part of preparation for implementing a project on complex studying metagenomes of whole blood and skin biopsies of psoriatic patients.

Narrow-band phototherapy and sodium salt of the synthetic diamide gamma-D-glutamyl-D-tryptophan as a combined method of psoriasis treatment: comprehensive and comparative evaluation

The paper presents the results of a comparative study of various immunosuppressive treatment methods of medium severity vulgar psoriasis (PASI from 10 to 20). The parameters used were PASI indices, p53 apoptosis marker expression indices, and expression indices of T-regulatory cell marker Foxp3. The study involved 96 patients, from 18 to 60 years old, divided by randomization into three groups. Patients in the 1st group (n = 32) received narrow-band phototherapy according to a 4-day regimen. We used the Waldmann UV-7002K instrument and F79/120W-TL01 lamps generating radiation with a maximum emission at a wavelength of 311 nm. We started with a dose of 0.05–0.1 J/cm2, subsequently increased by 0.05–0.1 J/cm2 for each procedure, in the absence of erythema. In total, patients received 12–15 procedures, with a course dose of 4.7–7.65 J/cm2. In the 2nd group (n = 32), patients were treated with the sodium salt of the synthetic gamma-D-glutamyl-D tryptophan dipeptide. Patients of the 3rd group (n = 32) underwent combination therapy, which included both methods described above. As a result of treatment, the greatest decrease in the PASI index, as well as the level of expression of the marker of Foxp3 T-regulatory cells, was observed among patients who received the combined regimen. The data obtained indicate the high therapeutic efficacy of narrow-band phototherapy in combination with the sodium salt of the synthetic gamma-D glutamyl-D tryptophan synthetic dipeptide. It was also noted that the immunohistochemical marker p53, reflecting the cellular renewal of psoriatic papule keratinocytes, is an informative molecular-cellular indicator of the effectiveness of narrow-band phototherapy.

How It Works: The Immunology Underlying Phototherapy

Phototherapeutic modalities induce apoptosis of keratinocytes and immune cells, impact cytokine production, downregulate the IL-23/Th17 axis, and induce regulatory T cells. As in anti-IL-17 or anti-IL-23 antibody treatment, the dual action of phototherapy on skin and the immune system is likely responsible for sustained resolution of lesions in diseases such as psoriasis. In cutaneous T cell lymphoma, phototherapy may function by causing tumor cell apoptosis and eliminating the neoplastic and inflammatory infiltrate. Further research on phototherapeutic mechanisms will help advance, optimize, and refine dermatologic treatments and may open up novel avenues for treatment strategies in dermatology and beyond.

Indoor salt water baths followed by artificial ultraviolet B light for chronic plaque psoriasis

BACKGROUND

Chronic plaque psoriasis is an immune-mediated, chronic, inflammatory skin disease, which can impair quality of life and social interaction. Disease severity can be classified by the psoriasis area and severity index (PASI) score ranging from 0 to 72 points. Indoor artificial salt bath with or without artificial ultraviolet B (UVB) light is used to treat psoriasis, simulating sea bathing and sunlight exposure; however, the evidence base needs clear evaluation.

OBJECTIVES

To assess the effects of indoor (artificial) salt water baths followed by exposure to artificial UVB for treating chronic plaque psoriasis in adults.

SEARCH METHODS

We searched the following databases up to June 2019: the Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We also searched five trial registers, and checked the reference lists of included studies, recent reviews, and relevant papers for further references to relevant trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of salt bath indoors followed by exposure to artificial UVB in adults who have been diagnosed with chronic plaque type psoriasis. We included studies reporting between-participant data and within-participant data. We evaluated two different comparisons: 1) salt bath + UVB versus other treatment without UVB; eligible comparators were exposure to psoralen bath, psoralen bath + artificial ultraviolet A UVA) light, topical treatment, systemic treatment, or placebo, and 2) salt bath + UVB versus other treatment + UVB or UVB only; eligible comparators were exposure to bath containing other compositions or concentrations + UVB or UVB only.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We used GRADE to assess the certainty of the evidence. The primary efficacy outcome was PASI-75, to detect people with a 75% or more reduction in PASI score from baseline. The primary adverse outcome was treatment-related adverse events requiring withdrawal. For the dichotomous variables PASI-75 and treatment-related adverse events requiring withdrawal, we estimated the proportion of events among the assessed participants. The secondary outcomes were health-related quality of life using the Dermatology Life Quality Index, (DLQI) pruritus severity measured using a visual analogue scale, time to relapse, and secondary malignancies.

MAIN RESULTS

We included eight RCTs: six reported between-participant data (2035 participants; 1908 analysed), and two reported within-participant data (70 participants, 68 analysed; 140 limbs; 136 analysed). One study reported data for the comparison salt bath with UVB versus other treatment without UVB; and eight studies reported data for salt bath with UVB versus other treatment with UVB or UVB only. Of these eight studies, only five reported any of our pre-specified outcomes and assessed the comparison of salt bath with UVB versus UVB only. The one included trial that assessed salt bath plus UVB versus other treatment without UVB (psoralen bath + UVA) did not report any of our primary outcomes. The mean age of the participants ranged from 41 to 50 years of age in 75% of the studies. None of the included studies reported on the predefined secondary outcomes of this review. We judged seven of the eight studies as at high risk of bias in at least one domain, most commonly performance bias. Total trial duration ranged between at least two months and up to 13 months. In five studies, the median participant PASI score at baseline ranged from 15 to 18 and was balanced between treatment arms. Three studies did not report PASI score. Most studies were conducted in Germany; all were set in Europe. Half of the studies were multi-centred (set in spa centres or outpatient clinics); half were set in a single centre in either an unspecified settings, a psoriasis daycare centre, or a spa centre. Commercial spa or salt companies sponsored three of eight studies, health insurance companies funded another, the association of dermatologists funded another, and three did not report on funding. When comparing salt bath plus UVB versus UVB only, two between-participant studies found that salt bath plus UVB may improve psoriasis when measured using PASI 75 (achieving a 75% or more reduction in PASI score from baseline) (risk ratio (RR) 1.71, 95% confidence interval (CI) 1.24 to 2.35; 278 participants; low-certainty evidence). Assessment was conducted at the end of treatment, which was equivalent to six to eight weeks after start of treatment. The two trials which contributed data for the primary efficacy outcome were conducted by the same group, and did not blind outcome assessors. The German Spas Association funded one of the trials and the funding source was not stated for the other trial. Two other between-participant studies found salt bath plus UVB may make little to no difference to outcome treatment-related adverse events requiring withdrawal compared with UVB only (RR 0.96, 95% CI 0.35 to 2.64; 404 participants; low-certainty evidence). One of the studies reported adverse events, but did not specify the type of events; the other study reported skin irritation. One within-participant study found similar results, with one participant reporting severe itch immediately after Dead Sea salt soak in the salt bath and UVB group and two instances of inadequate response to phototherapy and conversion to psoralen bath + UVA reported in the UVB only group (low-certainty evidence).

AUTHORS' CONCLUSIONS

Salt bath with artificial ultraviolet B (UVB) light may improve psoriasis in people with chronic plaque psoriasis compared with UVB light treatment alone, and there may be no difference in the occurrence of treatment-related adverse events requiring withdrawal. Both results are based on data from a limited number of studies, which provided low-certainty evidence, so we cannot draw any clear conclusions. The reporting of our pre-specified outcomes was either non-existent or limited, with a maximum of two studies reporting a given outcome. The same group conducted the two trials which contributed data for the primary efficacy outcome, and the German Spas Association funded one of these trials. We recommend further RCTs that assess PASI-75, with detailed reporting of the outcome and time point, as well as treatment-related adverse events. Risk of bias was an issue; future studies should ensure blinding of outcome assessors and full reporting.

Persistence of Inflammatory Phenotype in Residual Psoriatic Plaques in Patients on Effective Biologic Therapy

Many psoriasis patients treated with biologics do not achieve total skin clearance. These patients possess residual plaques despite ongoing biologic treatment. To elucidate mechanisms of plaque persistence despite overall good drug response, we studied 50 subjects: psoriasis patients with residual plaques treated with one of three different biologics, untreated patients, and healthy controls. Skin biopsies from all subjects were characterized using three methods: mRNA expression, histology, and FACS of hematopoietic skin cells. Although all three methods provided evidence of drug effect, gene expression analysis revealed the persistence of key psoriasis pathways in treated plaques, including granulocyte adhesion and diapedesis, T helper type17 activation pathway, and interferon signaling with no novel pathways emerging. Focal decreases in parakeratosis and keratinocyte proliferation and differential reduction in IL-17 producing CD103- T cells, but no change in CD103+ tissue-resident memory T cells were observed. Of note, antitumor necrosis factor increased the interferon signaling pathway already present. Interestingly mast cells were the dominant source of IL-22 in all psoriasis subjects. These data suggest that while subtle differences can be observed in drug-treated plaques, underlying biologic mechanisms are similar to those present in untreated psoriatic lesions.

Effect of narrow-band ultraviolet B phototherapy, methotrexate, and combined narrow-band ultraviolet B phototherapy with methotrexate on serum cathelicidin and vitamin D in patients with psoriasis vulgaris

Objective: This study aimed to evaluate the efficacy of narrow-band ultraviolet B (NB-UVB) phototherapy, methotrexate, and combined NB-UVB phototherapy with methotrexate in the treatment of psoriasis vulgaris and to assess their effects on serum cathelicidin and vitamin D.Methods: This study was conducted on 60 patients with psoriasis vulgaris. They were divided into three groups (20 patients each); Group (A) was treated with NB-UVB phototherapy. Group (B) was treated with methotrexate. Group (C) was treated with combined NB-UVB phototherapy with methotrexate. Patients were assessed with Psoriasis Area and Severity Index (PASI score), serum cathelicidin and vitamin D at the first visit and after three months of treatments.Results: The highest mean PASI score percent improvement was reported in the combined NB-UVB phototherapy with methotrexate (92%). There was a significant increase in serum vitamin D after treatments with NB-UVB phototherapy and combined NB-UVB phototherapy with methotrexate (p < .001). There was a significant decrease in cathelicidin after three months of treatment with combined NB-UVB phototherapy with methotrexate (p < .01).Conclusion: This study could contribute to the hypothesis considering the role of cathelicidin and vitamin D in the pathogenesis of psoriasis. The combined NB-UVB phototherapy with methotrexate had the highest clinical improvement of psoriasis vulgaris.

Complexities in Genetics of Psoriatic Arthritis

PURPOSE OF THE REVIEW

To provide a general overview and current challenges regarding the genetics of psoriatic disease. With the use of integrative medicine, multiple candidate loci identified to date in psoriatic disease will be annotated, summarized, and visualized. Recent studies reporting differences in genetic architecture between psoriatic arthritis and cutaneous-only psoriasis will be highlighted.

RECENT FINDINGS

Focusing on functional pathways that connect previously identified genetic variants can increase our understanding of psoriatic diseases. The genetic architecture differs between psoriatic arthritis and cutaneous-only psoriasis with arthritis-specific signals in linkage disequilibrium independent of the published psoriasis signals. Integrative medicine is helpful in understanding cellular mechanisms of psoriatic diseases. Careful selection of the psoriatic disease cohort has translated into mechanistic differences among psoriatic arthritis and cutaneous psoriasis.

Loss of the Epigenetic Mark 5-hmC in Psoriasis: Implications for Epidermal Stem Cell Dysregulation

Epigenetic regulation has a profound influence on stem cell fate during normal development in maintenance of physiologic tissue homeostasis. Here we report diminished ten-eleven translocation (TET) methylcytosine dioxygenase expression and loss of the DNA hydroxymethylation mark 5-hydroxymethylcytosine (5-hmC) in keratinocyte stem cells and transit amplifying cells in human psoriasis and in imiquimod-induced murine psoriasis. Loss of 5-hmC was associated with dysregulated keratinocyte stem cell kinetics, resulting in accumulation of nestin and FABP5-expressing transit amplifying cells to produce classic psoriatic epidermal architecture. Moreover, 5-hmC loss was accompanied by diminished TET1 and TET2 mRNA expression. Genome-wide mapping of epidermal 5-hmC in murine psoriasis revealed loci-specific loss of 5-hmC in genes regulating stem cell homeostasis, including MBD1, RTN1, STRN4, PRKD2, AKT1, and MAPKAP2, as well as those associated with RAR and Wnt/β-catenin signaling pathways. In vitro restoration of TET expression by ascorbic acid was accomplished in cultured human keratinocyte stem cells to show similar Ca⁺⁺-induced differentiation, resulting in increased 5-hmC levels and reduced nestin expression. To our knowledge, an epigenetic deficiency in psoriasis with relevance to stem cell dysregulation has not been previously reported. This observation raises the possibility that epigenetic modifiers that impact on the TET-5-hmC pathway may be a relevant approach of heretofore unappreciated therapeutic utility.

Resolution of plaque-type psoriasis: what is left behind (and reinitiates the disease)

Psoriasis is a chronic inflammatory skin disease that involves numerous types of immune cells and cytokines resulting in an inflammatory feedback loop and hyperproliferation of the epidermis. A more detailed understanding of the underlying pathophysiology has revolutionized anti-psoriatic treatment and led to the development of various new drugs targeting key inflammatory cytokines such as IL-17A and IL-23. Successfully treated psoriatic lesions often resolve completely, leaving nothing visible to the naked eye. However, such lesions tend to recur within months at the exact same body sites. What is left behind at the cellular and molecular levels that potentially reinitiates psoriasis? Here, we elucidate the cellular and molecular “scar” and its imprints left after clinical resolution of psoriasis treated with anti-TNFα, anti-IL-17, or anti-IL-23 antibodies or phototherapy. Hidden cytokine stores and remaining tissue-resident memory T cells (TRMs) might hold the clue for disease recurrence.

Advances in phototherapy for psoriasis and atopic dermatitis

Introduction: Phototherapy has long been used for the treatment of inflammatory skin diseases, such as psoriasis and atopic dermatitis. The most frequent treatment approach utilizes ultraviolet (UV) light, however, recently, different lasers and low-level light therapies (LLLT) emitting wavelengths in the spectrum of the visible light have also been tried for the treatment of inflammatory skin diseases with variable success.Areas covered: This review provides an update on the different forms of phototherapy used for the treatment of psoriasis and atopic dermatitis. The proposed mechanism of action of the different phototherapeutical approaches are covered, including the immunosuppressive effect of UV light, the anti-inflammatory effect of vascular lasers and the LLLT induced photobiomodulation. The clinical efficacy of the different treatment options is also discussed.Expert opinion: Based on the efficacy and safety, NB-UVB represents the gold standard for treating psoriasis and atopic dermatitis. The UVB excimer laser and excimer lamp might be the best option for clearing localized therapy-resistant lesions. Home UV phototherapy systems might promote treatment adherence and better compliance of the patients. Vascular lasers, IPLs and LLLT, however, can not currently be recommended for the treatment of inflammatory skin diseases because of the lack of well-controlled studies.

Short-term changes in frequencies of circulating leukocytes associated with narrowband UVB phototherapy in people with clinically isolated syndrome

Clinically isolated syndrome (CIS) is the earliest clinical episode in multiple sclerosis (MS). Low environmental exposure to UV radiation is implicated in risk of developing MS, and therefore, narrowband UVB phototherapy might delay progression to MS in people with CIS. Twenty individuals with CIS were recruited, and half were randomised to receive 24 sessions of narrowband UVB phototherapy over a period of 8 weeks. Here, the effects of narrowband UVB phototherapy on the frequencies of circulating immune cells and immunoglobulin levels after phototherapy are reported. Peripheral blood samples for all participants were collected at baseline, and 1, 2, 3, 6 and 12 months after enrolment. An extensive panel of leukocyte populations, including subsets of T cells, B cells, monocytes, dendritic cells, and natural killer cells were examined in phototherapy-treated and control participants, and immunoglobulin levels measured in serum. There were significant short-term increases in the frequency of naïve B cells, intermediate monocytes, and fraction III FoxP3+ T regulatory cells, and decreases in switched memory B cells and classical monocytes in phototherapy-treated individuals. Since B cells are increasingly targeted by MS therapies, the effects of narrowband UVB phototherapy in people with MS should be investigated further.

Cold atmospheric plasma ameliorates imiquimod-induced psoriasiform dermatitis in mice by mediating antiproliferative effects

Psoriasis is a chronic hyperproliferative skin disease characterised by excessive growth of keratinocytes. Indeed, inducing keratinocyte apoptosis is a key mechanism responsible for psoriatic plaques clearance following some important existing therapies, which display pro-oxidant activity. Cold atmospheric plasma (CAP), acting as a tuneable source of reactive oxygen and nitrogen species (RONS), can controllably transfer RONS to the cellular environment, deliver antiproliferative RONS concentrations and exert antiproliferative and proapoptotic effects. This study was undertaken to evaluate the therapeutic potential of CAP in psoriasis. We used cell models of psoriasis-like inflammation by adding lipopolysaccharide (LPS) or tumour necrosis factor alpha (TNF-α) to HaCaT keratinocytes. Indirect plasma, plasma-activated medium (PAM), was administered to HaCaT cells. Atmospheric pressure plasma jet (APPJ) was applied directly to imiquimod (IMQ)-induced psoriasiform dermatitis in mice. The results showed that PAM induced an increase in intracellular ROS and caused keratinocyte apoptosis. Moreover, cells under inflammation showed lesser viability and larger apoptosis rate. With repeated administration of APPJ, psoriasiform lesions showed ameliorated morphological manifestation and reduced epidermal proliferation. Overall, this study supports that CAP holds good potential in psoriasis treatment.

From Early Immunomodulatory Triggers to Immunosuppressive Outcome: Therapeutic Implications of the Complex Interplay Between the Wavebands of Sunlight and the Skin

Phototherapy is an efficient treatment for many cutaneous diseases that involve the activation of inflammatory pathways or the overgrowth of cells with aberrant phenotype. In this review, we discuss recent advances in photoimmunology, focusing on the effects of UV-based therapies currently used in dermatology. We describe the molecular responses to the main forms of photo(chemo)therapy such as UVB, UVA-1, and PUVA that include the triggering of apoptotic or immunosuppressive pathways and help to clear diseased skin. The early molecular response to UV involves DNA photoproducts, the isomerization of urocanic acid, the secretion of biophospholipids such as platelet activating factor (PAF), the activation of aryl hydrocarbon receptor and inflammasome, and vitamin D synthesis. The simultaneous and complex interaction of these events regulates the activity of the immune system both locally and systemically, resulting in apoptosis of neoplastic and/or benign cells, reduction of cellular infiltrate, and regulation of cytokines and chemokines. Regulatory T-cells and Langerhans cells, among other skin-resident cellular populations, are deeply affected by UV exposure and are therefore important players in the mechanisms of immunomodulation and the therapeutic value of UV in all its forms. We weigh the contribution of these cells to the therapeutic application of UV and how they may participate in transferring the direct impact of UV on the skin into local and systemic immunomodulation. Moreover, we review the therapeutic mechanisms revealed by clinical and laboratory animal investigations in the most common cutaneous diseases treated with phototherapy such as psoriasis, atopic dermatitis, vitiligo, and cutaneous T-cell lymphoma. Better understanding of phototherapeutic mechanisms in these diseases will help advance treatment in general and make future therapeutic strategies more precise, targeted, personalized, safe, and efficient.

Exposure to Ultraviolet Radiation in the Modulation of Human Diseases

This review focuses primarily on the beneficial effects for human health of exposure to ultraviolet radiation (UVR). UVR stimulates anti-inflammatory and immunosuppressive pathways in skin that modulate psoriasis, atopic dermatitis, and vitiligo; suppresses cutaneous lesions of graft-versus-host disease; and regulates some infection and vaccination outcomes. While polymorphic light eruption and the cutaneous photosensitivity of systemic lupus erythematosus are triggered by UVR, polymorphic light eruption also frequently benefits from UVR-induced immunomodulation. For systemic diseases such as multiple sclerosis, type 1 diabetes, asthma, schizophrenia, autism, and cardiovascular disease, any positive consequences of UVR exposure are more speculative, but could occur through the actions of UVR-induced regulatory cells and mediators, including 1,25-dihydroxy vitamin D₃, interleukin-10, and nitric oxide. Reduced UVR exposure is a risk factor for the development of several inflammatory, allergic, and autoimmune conditions, including diseases initiated in early life. This suggests that UVR-induced molecules can regulate cell maturation in developing organs.

Desired response to phototherapy vs photoaggravation in psoriasis: what makes the difference?

Psoriasis commonly responds beneficially to UV radiation from natural sunlight or artificial sources. Therapeutic mechanisms include the proapoptotic and immunomodulating effects of UV, affecting many cells and involving a variety of pro- and anti-inflammatory cytokines, downregulating the Th17/IL-23 response with simultaneous induction of regulatory immune cells. However, exposure to UV radiation in a subset of psoriasis patients leads to exacerbation of the disease. We herein shed light on the predisposing factors of photosensitive psoriasis, including genetics (such as HLA-Cw*0602 or CARD14), gender and coexisting photodermatoses such as polymorphic light eruption (PLE) in the context of potential molecular mechanisms behind therapeutic photoresponsiveness or photoaggravation. UV-induced damage/pathogen-associated molecular patterns, damage to self-coding RNA (signalling through Toll-like receptors), certain antimicrobial peptides and/or inflammasome activation may induce innate immunity, leading to psoriasis at the site of UV exposure when there is concomitant, predisposing resistance against UV-induced suppression of the adaptive immune response (like in PLE) that otherwise would act to reduce psoriasis.

NB-UVB irradiation downregulates keratin-17 expression in keratinocytes by inhibiting the ERK1/2 and STAT3 signaling pathways

Keratin-17 (K17) is a cytoskeletal protein produced by keratinocytes (KCs), which is overexpressed in psoriasis and may play a pivotal role in its pathogenesis. Narrow-band ultraviolet B (NB-UVB) irradiation is used as a general treatment for psoriasis, although its impact on K17 expression has yet to be determined. In this study, we aimed to investigate the effect of NB-UVB irradiation on K17 expression and its signaling pathways. After exposure to NB-UVB irradiation, immortalized human keratinocytes (HaCaT cells) were analyzed by flow cytometry, CCK-8 assays and transmission electron microscopy to examine proliferation. Meanwhile, K17 expression in primary human epithelial keratinocytes was detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis and immunofluorescence. HaCaT cells pre-incubated with PD-98059 and piceatannol were subjected to western blot analysis to examine ERK1/2 and STAT3 phosphorylation. The ears of mice treated with imiquimod (IMQ) and irradiated by NB-UVB were taken to examine K17 expression by qRT-PCR, western blot analysis, and immunofluorescence. Our results showed that 400 mJ/cm² of NB-UVB irradiation was the maximum tolerable dose for HaCaT cells and could cause inhibited HaCaT cell proliferation and moderate increase of the early apoptosis. Furthermore, NB-UVB irradiation could downregulate K17 expression by inhibiting the ERK1/2 and STAT3 signaling pathways. In experiments conducted in vivo, NB-UVB irradiation with doses of MED or higher could eliminate the IMQ-induced psoriasis-like dermatitis and inhibit K17 expression. These results indicated that NB-UVB irradiation may eliminate chronic psoriatic plaques by suppressing K17 expression via the ERK1/2 and STAT3 signaling pathways.

Medical applications of nonthermal atmospheric pressure plasma in dermatology

Plasma is an ionized gas that consists of positively and negatively charged particles, neutral atoms, and photons. Recent developments in plasma sources have made it possible to generate room-temperature plasma in the "open air", thus enabling the application of plasma in vivo. Using nonthermal plasma, active agents can be efficiently delivered to target cells without creating thermal damage. Also known as cold atmospheric pressure plasma (CAP), nonthermal atmospheric pressure plasma offers innovative medical applications. In this context, it has also gained wide attention in the field of dermatology. The complex and variable mixture of active agents in plasma - predominantly reactive oxygen and nitrogen species (ROS, RNS) - can control or trigger complex biochemical reactions, achieving the desired effects in a dose-dependent manner. The objective of the present review is to present potential applications of plasma in dermatology and analyze its potential mechanisms of action.

Influence of narrowband ultraviolet B phototherapy on serum tumour necrosis factor-like weak inducer of apoptosis (TWEAK) in patients with psoriasis

Psoriasis is characterized by keratinocyte resistance to apoptosis. We recently demonstrated an increase in serum tumour necrosis factor-like weak inducer of apoptosis (TWEAK) in patients after topical treatment for psoriasis. We decided to verify whether narrowband ultraviolet B (NB-UVB) has a similar effect. Serum concentration of TWEAK was estimated in patients with exacerbated plaque psoriasis treated with NB-UVB. Baseline TWEAK levels were similar in patients with psoriasis and healthy controls, and Psoriasis Area and Severity Index (PASI) correlated inversely with TWEAK levels. Treatment with NB-UVB caused a significant reduction in PASI and concurrent increase in serum TWEAK. This finding may be due to increased expression of TWEAK receptor in psoriatic skin, which has been reported previously, with consequent binding of excess soluble TWEAK during treatment and subsequent release after treatment. Severity of plaque psoriasis and its improvement after NB-UVB treatment may be associated with TWEAK concentrations. The importance of our findings remains to be established.

Critical role of environmental factors in the pathogenesis of psoriasis

Psoriasis is a common cutaneous disease with multifactorial etiology including genetic and non-genetic factors, such as drugs, smoking, drinking, diet, infection and mental stress. Now, the role of the interaction between environmental factors and genetics are considered to be a main factor in the pathogenesis of psoriasis. However, it is a challenge to explore the mechanisms how the environmental factors break the body balance to affect the onset and development of psoriasis. In this article, we review the pathogenesis of psoriasis and summarize numerous clinical data to reveal the association between environmental factors and psoriasis. In addition, we focus on the mechanisms of environmental risk factors impact on psoriasis and provide a series of potential treatments against environmental risk factors.

A Dynamic Model for Prediction of Psoriasis Management by Blue Light Irradiation

Clinical investigations prove that blue light irradiation reduces the severity of psoriasis vulgaris. Nevertheless, the mechanisms involved in the management of this condition remain poorly defined. Despite the encouraging results of the clinical studies, no clear guidelines are specified in the literature for the irradiation scheme regime of blue light-based therapy for psoriasis. We investigated the underlying mechanism of blue light irradiation of psoriatic skin, and tested the hypothesis that regulation of proliferation is a key process. We implemented a mechanistic model of cellular epidermal dynamics to analyze whether a temporary decrease of keratinocytes hyper-proliferation can explain the outcome of phototherapy with blue light. Our results suggest that the main effect of blue light on keratinocytes impacts the proliferative cells. They show that the decrease in the keratinocytes proliferative capacity is sufficient to induce a transient decrease in the severity of psoriasis. To study the impact of the therapeutic regime on the efficacy of psoriasis treatment, we performed simulations for different combinations of the treatment parameters, i.e., length of treatment, fluence (also referred to as dose), and intensity. These simulations indicate that high efficacy is achieved by regimes with long duration and high fluence levels, regardless of the chosen intensity. Our modeling approach constitutes a framework for testing diverse hypotheses on the underlying mechanism of blue light-based phototherapy, and for designing effective strategies for the treatment of psoriasis.

Phototherapy of Psoriasis, a Chronic Inflammatory Skin Disease

Phototherapy is an effective treatment modality for several skin diseases which has been in use from the era of the Egyptians. Insight into its mode of action has gradually accumulated over the past decades. A crucial biological effect of ultraviolet radiation is the induction of apoptosis in T lymphocytes and in keratinocytes in the epidermis. Via this mechanism inflammation-induced pathological changes characteristic of psoriasis are counteracted.Phototherapy remains the only therapeutic option for certain patient groups where modification of the systemic immune reactions is contraindicated, such as by HIV, internal malignancy or pregnancy. UVB treatment is highly cost-effective, which is important in this age of increasing health care costs.

Risk of skin cancer in patients on chronic haemodialysis: a nationwide, population-based study in Taiwan

BACKGROUND

Patients on chronic haemodialysis (HD) have a higher incidence of cancer. However, the risk of skin cancer in this population has rarely been investigated.

OBJECTIVES

To investigate the risk of nonmelanoma skin cancer (NMSC) and cutaneous melanoma in patients on chronic HD and to explore the associated risk factors.

METHODS

We performed retrospective cohort and nested case-control studies using records in the Taiwanese National Health Insurance Research Database between 1999 and 2013. The HD cohort included 79 668 incident patients on HD, for whom the standardized incidence ratios (SIRs) for incident NMSC and cutaneous melanoma were determined. In the nested case-control study, patients on HD with NMSC were matched to those without skin cancers. The impact of various factors on the development of NMSC was determined by conditional logistic regression analysis.

RESULTS

Among the 79 668 patients on HD, 248 cases of NMSC and 22 cases of cutaneous melanoma occurred after a mean 4·95 years of follow-up. The SIRs for NMSC and cutaneous melanoma in patients on HD were 1·58 (95% confidence interval 1·39-1·79) and 1·44 (95% confidence interval 0·91-2·19), respectively. Of the patients on HD, a higher risk of NMSC was found in men (1·5-fold), South Taiwan residents (twofold) and patients with uraemic pruritus after long-term antihistamine treatment (1·53-fold). However, the incidence of NMSC was not increased in patients with uraemic pruritus receiving ultraviolet B phototherapy.

CONCLUSIONS

Patients on chronic HD are at higher risk of NMSC. Uraemic pruritus further increases the risk of NMSC, which might be prevented by ultraviolet B phototherapy.

Recent advances in phototherapy for psoriasis

Phototherapy involves repeated exposure of the skin to ultraviolet light to treat various inflammatory skin conditions such as psoriasis. Recent studies have identified specific immunologic effects of phototherapy that may underlie phototherapy efficacy. Furthermore, recent advancements have been made in developing safe and effective targeted phototherapy modalities for difficult-to-treat areas such as scalp psoriasis. Targeted phototherapy in the form of the excimer laser holds potential for more aggressive, effective treatment and long-lasting remission of psoriasis. Phototherapy is now also used successfully with biologic agents as combination therapy to treat recalcitrant psoriasis. Therefore, though one of the oldest therapeutic modalities for psoriasis, phototherapy remains a mainstay treatment with promise for further advancement.