Psoriasis: Keratinocytes or Immune Cells - Which Is the Trigger?

Investigation of Omega-3 Polyunsaturated Fatty Acid Biological Activity in a Tissue-Engineered Skin Model Involving Psoriatic Cells

Clinical studies have shown that diets enriched with omega-3 (also know as n-3) polyunsaturated fatty acids could relieve the symptoms of patients with psoriasis. However, the mechanisms involved remain poorly understood. The aim of this study was to investigate the effects of α-linolenic acid (ALA) on the proliferation and differentiation of psoriatic keratinocytes in a three-dimensional skin model. Skin models featuring healthy (healthy substitute) or psoriatic (psoriatic substitute) cells were engineered by the self-assembly method of tissue engineering using a culture medium supplemented with 10 μM ALA in comparison with the regular unsupplemented medium. ALA decreased keratinocyte proliferation and improved psoriatic substitute epidermal differentiation, as measured by decreased Ki67 staining and increased protein expression of FLG and loricrin. The added ALA was notably incorporated into the epidermal phospholipids and metabolized into long-chain n-3 polyunsaturated fatty acids, mainly eicosapentaenoic acid and n-3 docosapentaenoic acid. ALA supplementation led to increased levels of eicosapentaenoic acid derivatives (15-hydroxyeicosapentaenoic acid and 18-hydroxyeicosapentaenoic acid) as well as a decrease in levels of omega-6 (also know as n-6) polyunsaturated fatty acid lipid mediators (9-hydroxyoctadecadienoic acid, 12-hydroxyeicosatetraenoic acid, and leukotriene B₄). Furthermore, the signal transduction mediators extracellular signal‒regulated kinases 1 and 2 were the kinases most activated after ALA supplementation. Taken together, these results show that ALA decreases the pathologic phenotype of psoriatic substitutes by normalizing keratinocyte proliferation and differentiation in vitro.

Integrated analysis of immune-related long noncoding RNAs as diagnostic biomarkers in psoriasis

Background

Psoriasis is a chronic immune-mediated inflammatory dermatosis. Long noncoding RNAs (lncRNAs) play an important role in immune-related diseases. This study aimed to identify potential immune-related lncRNA biomarkers for psoriasis.

Methods

We screened differentially expressed immune-related lncRNAs biomarkers using GSE13355 (skin biopsy samples of 180 cases) from Gene Expression Omnibus (GEO). Moreover, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and Gene Set Enrichment Analysis (GSEA) were performed to explore biological mechanisms in psoriasis. In addition, we performed LASSO logistic regression to identify potential diagnostic lncRNAs and further verify the diagnostic value and relationship with drug response using two validation sets: GSE30999 (skin biopsy samples of 170 cases) and GSE106992 (skin biopsy samples of 192 cases). Furthermore, we estimated the degree of infiltrated immune cells and investigated the correlation between infiltrated immune cells and diagnostic lncRNA biomarkers.

Results

A total of 394 differentially expressed genes (DEGs) were extracted from gene expression profile. GO and KEGG analysis of target genes found that immune-related lncRNAs were primarily associated with epidermis development, skin development, collagen-containing extracellular matrix, and glycosaminoglycan binding and mainly enriched in cytokine-cytokine receptor interaction and influenza A and chemokine signaling pathway. We found that LINC01137, LINC01215, MAPKAPK5-AS1, TPT1-AS1, CARMN, CCDC18-AS1, EPB41L4A-AS, and LINC01214 exhibited well diagnostic efficacy. The ROC and ROC CI were 0.944 (0.907–0.982), 0.953 (0.919–0.987), 0.822 (0.758–0.887), 0.854 (0.797–0.911), 0.957(0.929–0.985), 0.894 (0.846–0.942), and 0.964 (0.937–0.991) for LINC01137, LINC01215, MAPKAPK5-AS1, TPT1-AS1,CARMN, CCDC18-AS1, EPB41L4A-AS1, and LINC01214. LINC01137, LINC01215, and LINC01214 were correlated with drug response. LINC01137, CCDC18-AS1, and CARMN were positively correlated with activated memory CD4 T cell, activated myeloid dendritic cell (DC), neutrophils, macrophage M1, and T follicular helper (Tfh) cells, while negatively correlated with T regulatory cell (Treg). LINC01215, MAPKAPK5-AS1, TPT1-AS1, EPB41L4A-AS, and LINC01214 were negatively correlated with activated memory CD4 T cell, activated myeloid DC, neutrophils, macrophage M1, and Tfh, while positively correlated with Treg.

Conclusions

These findings indicated that these immune-related lncRNAs may be used as potential diagnostic and predictive biomarkers for psoriasis.

Systemic Immune-Inflammation Index (SII) Predicts Increased Severity in Psoriasis and Psoriatic Arthritis

Background: Psoriasis is a common chronic inflammatory dermatosis. Systemic immune inflammation index (SII) is an inflammation-based biomarker, which has been shown to be an effective prognostic factor in diseases with an inflammation-related etiology. Objectives: The aim of the present study was to investigate the potential efficacy of SII as a prognostic factor in patients with psoriasis and psoriatic arthritis. Materials and methods: This is a study developed based on the analysis of the medical records of patients with psoriasis. The study retrospectively evaluated the records of the participants for complete blood count results. The SII was calculated by the formula: neutrophil x platelet/lymphocyte. Neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR) and platelet-lymphocyte ratio (PLR) were determined. Results: SII was significantly higher in patients with psoriasis than in controls (578.1 vs. 396, p<0.001). The differences between the median NLR (2.2 vs. 1.5, p<0.001), MLR (0.25 vs. 0.21, p<0.001) and the mean red cell distribution width coefficient of variation (13.8 vs. 12.8, p<0.001) values of patient and control group were significant. SII was higher in patients with moderate/severe psoriasis than patients with mild psoriasis (687.3 vs. 506.6, p=0.034). A positive correlation was observed between SII and PASI (p<0.001; r=0.37). SII was higher in patients with arthritis than patients without (672.1 vs. 548.2, p=0.018). Conclusion: This is the first study to prove that SII might serve as an independent prognostic indicator for patients with psoriasis and psoriatic arthritis.

MicroRNA-31 Can Positively Regulate the Proliferation, Differentiation and Migration of Keratinocytes

In the past decades, the key roles of most microRNA in dermatosis and skin development have been explored one after another. Among them, microRNA-31 (miR-31) has a prominent role in the regulation of keratinocytes. Numerous studies show that miR-31 can positively regulate the proliferation, differentiation and cell activity of keratinocytes via regulating the NF-κB, RAS/MAPK, Notch signaling pathways, and some cytokines. At present, the interaction between miR-31 and the NF-κB signaling pathway in keratinocytes is a hot research topic. The positive feedback loop formed by miR-31 and NF-κB signaling may bring new ideas for the prevention of psoriasis. The abnormal state of keratinocytes is usually the pathological basis of many skin and immune system diseases. Therefore, strengthening the ability to regulate keratinocytes may be a breakthrough for a variety of diseases. At the same time, miR-31's capacity to accelerate wound healing via positively regulating keratinocytes should be further investigated in the treatment of chronic ulcers and trauma.

ACT1 Is Required for Murine IL-23-Induced Psoriasiform Inflammation Potentially Independent of E3 Ligase Activity

Psoriasis is a debilitating skin disease characterized by epidermal thickening, abnormal keratinocyte differentiation, and proinflammatory immune cell infiltrate into the affected skin. IL-17A plays a critical role in the etiology of psoriasis. ACT1, an intracellular adaptor protein and a putative ubiquitin E3 ligase, is essential for signal transduction downstream of the IL-17A receptor. Thus, IL-17A signaling in general, and ACT1 specifically, represent attractive targets for the treatment of psoriasis. We generated Act1 knockout and Act1 L286G knockin (ligase domain) mice to investigate the potential therapeutic effects of targeting ACT1 and its U-box domain, respectively. Act1 knockout, but not Act1 L286G knockin, mice were resistant to increases in CXCL1 plasma levels induced by subcutaneous injection of recombinant IL-17A. Moreover, in a mouse model of psoriasiform dermatitis induced by intradermal IL-23 injection, Act1 knockout, but not Act1 L286G knockin, was protective against increases in ear thickness, keratinocyte hyperproliferation, expression of genes for antimicrobial peptides and chemokines, and infiltration of monocytes and macrophages. Our studies highlight the critical contribution of ACT1 to proinflammatory skin changes mediated by the IL-23/IL-17 signaling axis and illustrate the need for further insight into ACT1 E3 ligase activity.

Pentacyclic triterpene compounds from loquat leaves reduce skin inflammation and epidermal hyperplasia in psoriasis via inhibiting the Th17 cells

Psoriasis is a refractory inflammatory skin disease affecting 2 %-3 % of the world population, characterized by the infiltration and hyper-proliferation of inflammatory cells and aberrant differentiation of keratinocytes. Targeting the IL-23/ Th17 axis has been well recognized as a promising therapeutic strategy, as the IL-23/ Th17 signal plays a vital role in the pathology of psoriasis. Three pentacyclic triterpene compounds isolated from loquat leaves have been reported with significant inhibitory effects on RORγt transcription activity and Th17 cell differentiation, and excellent performance in preventing lupus nephritis pathogenesis. However, the potential effects of these pentacyclic triterpene compounds on psoriasis remain unknown. In this study, we demonstrated the potent therapeutic effects of these pentacyclic triterpene compounds on psoriasis. These three pentacyclic triterpene compounds significantly alleviated skin inflammation as well as aberrant keratinocyte proliferation in an imiquimod-induced mouse psoriasis model. These compounds also inhibited the infiltration of immune cells and the level of pro-inflammatory cytokine in the dermis, as well as the cells number and changed the cytokine profiling expression of Th17 cells. These compounds could reduce the amount of CD4⁺ and CD8⁺ T cells in local lymph node, but not in spleen, which is different from hydrocortisone, the positive control treatment. These results suggest better performance of these compounds than steroids on treating psoriasis with less side effects on the integrated immune system. In summary, our findings uncover the potent therapeutic effects of pentacyclic triterpene compounds on psoriasis, providing potential candidate compounds for drug development.

Decoding Psoriasis: Integrated Bioinformatics Approach to Understand Hub Genes and Involved Pathways

BACKGROUND

Psoriasis is a chronic immune mediated skin disorder with global prevalence of 0.2- 11.4%. Despite rare mortality, the severity of the disease could be understood by the accompanying comorbidities, that has even led to psychological problems among several patients. The cause and the disease mechanism still remain elusive.

OBJECTIVE

To identify potential therapeutic targets and affecting pathways for better insight of the disease pathogenesis.

METHOD

The gene expression profile GSE13355 and GSE14905 were retrieved from NCBI, Gene Expression Omnibus database. The GEO profiles were integrated and the DEGs of lesional and non-lesional psoriasis skin were identified using the affy package in R software. The Kyoto Encyclopaedia of Genes and Genomes pathways of the DEGs were analyzed using clusterProfiler. Cytoscape, V3.7.1 was utilized to construct protein interaction network and analyze the interactome map of candidate proteins encoded in DEGs. Functionally relevant clusters were detected through Cytohubba and MCODE.

RESULTS

A total of 1013 genes were differentially expressed in lesional skin of which 557 were upregulated and 456 were downregulated. Seven dysregulated genes were extracted in non-lesional skin. The disease gene network of these DEGs revealed 75 newly identified differentially expressed gene that might have a role in development and progression of the disease. GO analysis revealed keratinocyte differentiation and positive regulation of cytokine production to be the most enriched biological process and molecular function. Cytokines -cytokine receptor was the most enriched pathways. Among 1013 identified DEGs in lesional group, 36 DEGs were found to have altered genetic signature including IL1B and STAT3 which are also reported as hub genes. CCNB1, CCNA2, CDK1, IL1B, CXCL8, MKI 67, ESR1, UBE2C, STAT1 and STAT3 were top 10 hub gene.

CONCLUSION

The hub genes, genomic altered DEGs and other newly identified differentially dysregulated genes would improve our understanding of psoriasis pathogenesis, moreover, the hub genes could be explored as potential therapeutic targets for psoriasis.

Intrinsic Abnormalities of Keratinocytes Initiate Skin Inflammation through the IL-23/T17 Axis in a MALT1-Dependent Manner

Increasing evidence has supported the crucial role of CARD14 in the pathogenesis of psoriasis, whereas the precise cellular signaling involved in skin physiopathology remains poorly understood. In this article, we show that neither genetic ablation of Il17a nor elimination of T cells was sufficient to restrain the skin inflammation in a CARD14-E138A-mutation-induced psoriasis-like mouse model, whereas depletion of Il23, which extremely blocked the IL-23/T17 axis, was more effective. Targeting CBM complex by conditional deletion of MALT1 or BCL10 in keratinocytes abrogated both the cutaneous and systemic inflammation of heterozygous Card14 ^E138A/+ mice. Selective inactivation of keratinocyte-specific MALT1 proteolytic activity strongly ameliorated the Card14 ^E138A/+- and Card14 ^ΔQ136/+-induced skin disease, which was reproduced by using the imiquimod-induced mouse model. Together, our results suggest a sequence of events under CARD14-mutation-induced psoriasis condition that keratinocyte-intrinsic activation of CBM complex initiates the skin inflammation depending on the IL-23/T17 axis. Targeting keratinocytes by inactivation of MALT1 paracaspase activity might be a promising therapeutic target for early psoriasis treatment.

FOXM1 regulates the proliferation, apoptosis and inflammatory response of keratinocytes through the NF-κB signaling pathway

Psoriasis is a common immune-mediated and genetic skin disease. Forkhead box M1 (FOXM1) is a member of FOX family that has been found to modulate skin disorders. However, its role in psoriasis remains unknown. Thus, we aimed to investigate the effect of FOXM1 on keratinocytes in response to tumor necrosis factor-α (TNF-α). The expression levels of FOXM1 in psoriasis tissues and normal skin tissues were examined using qRT-PCR and western blot. HaCaT cells were stimulated by TNF-α to mimic psoriasis in vitro. MTT assay was performed to assess cell proliferation. The caspase-3 activity and expression levels of bcl-2 and bax were determined to indicate cell apoptosis. The mRNA and secretion levels of IL-6, IL-23 and TGF-β were determined by qRT-PCR and ELISA, respectively. The NF-κB activation was assessed using western blot analysis. Our results demonstrated that FOXM1 was highly upregulated in psoriatic skin tissues and TNF-α-stimulated HaCaT cells. Knockdown of FOXM1 repressed cell proliferation of TNF-α-stimulated HaCaT cells. Knockdown of FOXM1 caused significant increases in caspase-3 activity, bax expression and decrease in bcl-2 expression in TNF-α-stimulated HaCaT cells. Moreover, FOXM1 knockdown also suppressed the TNF-α-induced production of IL-6, IL-23, and TGF-β in HaCaT cells. However, FOXM1 overexpression showed the opposite effect. Furthermore, the TNF-α-induced NF-κB activation was prevented by FOXM1 knockdown. Additionally, inhibition of NF-κB reversed the effects of FOXM1 on HaCaT cells. Taken together, these findings indicated that FOXM1 regulated cell proliferation, apoptosis and inflammation in TNF-α-induced HaCaT cells. The effects of FOXM1 were mediated by NF-κB pathway.

Comorbidity in Men with Psoriasis

Background:

Psoriasis is a chronic incurable disease, and patients develop associated diseases such as obesity, diabetes, high blood pressure, dyslipidemia.

Objective:

The aim of the study is to determine the frequency of comorbidities (obesity, diabetes, dyslipidemia, high blood pressure) in men with psoriasis, and the relationship between the duration of psoriasis and the occurrence of comorbidities.

Methods:

A prospective study was conducted and included 88 male subjects, mean age 52,70 (SD=± 14,05) years, mean psoriasis duration 15,13 (SD=±12,43) years.

Results:

The incidence of obesity was 30,68%, high blood pressure 29,55%, dyslipidemia 22,73%, diabetes 13,64%. There was a weak correlation between the duration of psoriasis and the occurrence of obesity (r=0,11), dyslipidemia (r=0,18), diabetes (r=0,01), and high blood pressure (r=-0,02).

Conclusion:

Comorbidities occur in men with psoriasis, and their occurrence is not related to the duration of the disease.

Catalpol ameliorates psoriasis-like phenotypes via SIRT1 mediated suppression of NF-κB and MAPKs signaling pathways

Psoriasis is a chronic inflammatory skin disease that affects approximately 2% of worldwide population, and causing long-term troubles to the patients. Therefore, it is urgent to develop safe and effective therapeutic drugs. Catalpol is a natural iridoid glucoside, that has several remarkable pharmacological effects, however, whether catalpol can alleviated psoriasis has not been explored. The goal of the present work is to study the role of catalpol in psoriasis in vivo and in vitro. Imiquimod-induced psoriasis-like mice were applied with different concentrations of catalpol for 8 consecutive days. The severity degree of psoriasis was estimated and the skin pathological changes were detected by H&E staining. Also, TNF-α-stimulated keratinocytes were treated with different concentrations of catalpol, then the oxidative stress and inflammation factors, as well as the expression of SIRT1 and activation of NF-kB and MAPK pathways were measured. The results showed that catalpol reduced the erythema, scaling, ear thickness, and changed pathological phenotypes in the lesioned skin region in mice. Treatment with catalpol significantly suppressed the oxidative stress and inflammatory reactions in vivo and in vitro, as reflected by the decreased secretion or expression of oxidative stress indicators and proinflammatory factors. Furthermore, the SIRT1 was up-regulated and the NF-κB and MAPKs signaling pathways were suppressed by the treatment of catalpol in vivo and in vitro. In summary, our data suggested that catalpol may have a therapeutic property of psoriasis by ameliorating oxidative stress and inflammation partly through SIRT1 mediated suppression of NF-κB and MAPKs pathways.

Abbreviation: CAT: catalase; ELISA: enzyme-linked immunosorbent assay; GSH: glutathione; HRP: horseradish peroxidase; IMQ: imiquimod; JNK: c-Jun NH 2-terminal kinases; MAPKs: mitogen-activated protein kinases; MDA: malondialdehyde; NC: negative control group; NF-kB: nuclear factor kappa B; PASI: psoriasis area and severity index; PVDF: polyvinylidene difluoride membranes; qRT-PCR: quantitative real time polymerase chain reaction; ROS: reactive oxygen species; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel; SIRT1: silent information regulator 1; SOD: Cu/Zn superoxide dismutase

The attentive focus on T cell-mediated autoimmune pathogenesis of psoriasis, lichen planus and vitiligo

T cell-mediated autoimmune skin diseases develop as a result of the aberrant immune response to the skin cells with T cells playing a central role. These chronic inflammatory skin diseases encompass various types including psoriasis, lichen planus and vitiligo. These diseases show similarities in their immune-pathophysiology. In the last decade, immunomodulating agents have been very successful in the management of these diseases thanks to a better understanding of the pathophysiology. In this review, we will discuss the immunopathogenic mechanisms and highlight the role of T lymphocytes in psoriasis, lichen planus and vitiligo. This study could provide new insights into a better understanding of targeted therapeutic pathways and biological therapies.

NLRP3 Inflammasome Activation Is Involved in LPA1-Mediated Brain Injury after Transient Focal Cerebral Ischemia

Lysophosphatidic acid receptor 1 (LPA₁) contributes to brain injury following transient focal cerebral ischemia. However, the mechanism remains unclear. Here, we investigated whether nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation might be an underlying mechanism involved in the pathogenesis of brain injury associated with LPA₁ following ischemic challenge with transient middle cerebral artery occlusion (tMCAO). Suppressing LPA₁ activity by its antagonist attenuated NLRP3 upregulation in the penumbra and ischemic core regions, particularly in ionized calcium-binding adapter molecule 1 (Iba1)-expressing cells like macrophages of mouse after tMCAO challenge. It also suppressed NLRP3 inflammasome activation, such as caspase-1 activation, interleukin 1β (IL-1β) maturation, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) speck formation, in a post-ischemic brain. The role of LPA₁ in NLRP3 inflammasome activation was confirmed in vitro using lipopolysaccharide-primed bone marrow-derived macrophages, followed by LPA exposure. Suppressing LPA₁ activity by either pharmacological antagonism or genetic knockdown attenuated NLRP3 upregulation, caspase-1 activation, IL-1β maturation, and IL-1β secretion in these cells. Furthermore, nuclear factor-κB (NF-κB), extracellular signal-regulated kinase 1/2 (ERK1/2), and p38 were found to be LPA₁-dependent effector pathways in these cells. Collectively, results of the current study first demonstrate that LPA₁ could contribute to ischemic brain injury by activating NLRP3 inflammasome with underlying effector mechanisms.

Possible Role of Lysine Demethylase 2A in the Pathophysiology of Psoriasis

Background

Psoriasis is a common chronic inflammatory skin disease. The development of psoriasis is dependent on many intercellular events such as innate immunity and T cell-mediated inflammation. Furthermore, genetic factors are strongly implicated in the pathophysiology of psoriasis. Although a variety of susceptible genes are identified, it is likely that many important genes remain undisclosed.

Objective

The aim of this study is to investigate the possible role of lysine demethylase 2A (KDM2A) in the pathophysiology of psoriasis.

Methods

We examined the expression of KDM2A using a well established imiquimod-induced psoriasiform dermatitis model.

Results

Immunohistochemistry analysis showed that expression of KDM2A was increased in imiquimod-induced psoriasiform dermatitis. Consistent with this result, KDM2A level was markedly increased in the epidermis of psoriatic patient. When keratinocytes were stimulated with TLR3 agonist poly(I:C), KDM2A was increased at both the mRNA and protein levels. Poly(I:C) increased the expression of psoriasis-related cytokines including tumor necrosis factor-α, interleukin-8, and CCL20, and KDM2A inhibitor daminozide enhanced the poly(I:C)-induced cytokine expression. Finally, topical co-application of imiquimod and daminozide exacerbated the imiquimod-induced psoriasiform dermatitis.

Conclusion

Together, these results suggest that KDM2A is increased to negatively regulate the inflammatory reaction of epidermal keratinocytes in psoriasis.

In vitro evaluation of potential benefits of a silica-rich thermal water (Monfortinho Thermal Water) in hyperkeratotic skin conditions

Thermal therapy has gained popularity over the years, and Portugal is one of the richest European countries in mineral therapeutic waters. The interest in the use of these natural mineral waters (NMW) for dermatologic purposes is continuously growing but there is a lack of scientific studies supporting its health benefits. The study aims to investigate the effect of a silica-rich NMW in skin cell homeostasis using two representative cell lines of the epidermis and dermis, keratinocytes and fibroblasts, respectively, in addition to a macrophage cell line. Mouse skin fibroblasts, macrophages and human keratinocytes were exposed to culture medium prepared with NMW. Cell metabolism (MTT or resazurin assays) and cell proliferation (trypan blue exclusion dye assay) were investigated. Migration (scratch-wound assay) and senescence (β-galactosidase activity assay) of fibroblasts were also studied. Exposure to NMW compromised the cell metabolic state of all the cell lines tested. This impairment was more pronounced in skin keratinocytes (60% reduction) relatively to skin fibroblasts (45% reduction) or macrophages (25% reduction). Proliferation of macrophages was reduced threefold upon exposure to thermal water, compared to controls. No differences were observed in migration between fibroblasts exposed to NMW and controls, while a potentiation of senescence of these cells was observed. Our results shed light in the bioactive effects of a silica-rich NMW supporting its therapeutic use. A reduction in both cell metabolism and proliferation of keratinocytes and macrophages supports the empirical clinical benefits of this NMW in hyperkeratotic conditions, such as psoriasis and atopic dermatitis.

Natural Compound Mixture, Containing Emodin, Genipin, Chlorogenic Acid, Cimigenoside, and Ginsenoside Rb1, Ameliorates Psoriasis-Like Skin Lesions by Suppressing Inflammation and Proliferation in Keratinocytes

Herbal combinations of Rhei Radix et Rhizoma, Gardeniae Fructus, Cimicifugae Rhizoma, and Ginseng Radix have been used in traditional formulas to treat the symptoms of heat and dryness. This study investigated the therapeutic effects of a natural compound mixture (PSM) of these herbal combinations, containing emodin, genipin, chlorogenic acid, cimigenoside, and ginsenoside Rb1, for the treatment of psoriasis and its underlying molecular mechanisms. PSM was applied topically to the dorsal skin lesions of imiquimod- (IMQ-) induced C57BL/6 mice, and the expression of the proinflammatory mediators was investigated. The topical application of 1% PSM reduced psoriasis-like symptoms in IMQ-induced C57BL/6 mice significantly. PSM also attenuated the production of IFN-γ, IL-1β, and IL-6 in skin lesions. Histological analysis showed that PSM had antipsoriatic effects by reducing the lesional epidermal thickness. Either M5 (IL-1α, IL-17A, IL-22, oncostatin M, and TNF-α, 10 ng/ml each) or IL-22- (100 ng/ml) stimulated HaCaT cells were used to examine the efficacy and underlying mechanism of PSM. In M5-stimulated HaCaT cells, PSM inhibited the production of C-X-C motif chemokine ligand (CXCL) 10 and C-C motif chemokine ligand (CCL) 20 effectively. Moreover, compared to the use of a single compound, it had synergistic inhibitory effects in CXCL8 production. PSM suppressed the phosphorylation of ERK1/2, p38, and STAT3 signaling pathways in M5-stimulated HaCaT cells. Furthermore, PSM reduced the proliferation rate and K16 and K17 expressions in IL-22-stimulated HaCaT cells by inhibiting the Akt/mTOR signaling pathway. These results suggest that PSM may have a therapeutic potential in the treatment of psoriasis lesions.

Association of psoriasis with colorectal cancer

BACKGROUND

The relation between psoriasis and colorectal cancer (CRC) was largely unclear.

OBJECTIVE

To investigate the association of psoriasis with CRC.

METHODS

A systematic review and meta-analysis of observational studies that examined the association of psoriasis with CRC was performed. We searched MEDLINE and Embase on March 24, 2020, for relevant studies. The Newcastle-Ottawa scale was used to evaluate the risk of bias of included studies. We conducted a random-effects model meta-analysis and subgroup analysis according to sex.

RESULTS

We included 9 cohort studies with 10,544,609 individuals. We found a significantly increased risk for CRC in patients with psoriasis (hazard ratio [HR], 1.16; 95% confidence interval [CI], 1.08-1.24). Subgroups analysis according to sex found significantly increased risk for CRC in female patients with psoriasis (HR, 1.41; 95% CI, 1.16-1.72) but not in male patients (HR, 1.18; 95% CI, 0.92-1.50).

LIMITATIONS

No data on psoriatic arthritis.

CONCLUSIONS

Patients with psoriasis have an increased risk for CRC. Gastroenterology consultation and colonoscopic examination are indicated for patients with psoriasis presenting with bowel symptoms.

The role of Th17 cells in psoriasis

T helper 17 (Th17) cells have been involved in the pathogenesis of many autoimmune and inflammatory diseases, like psoriasis, multiple sclerosis (MS), rheumatoid arthritis (RA), and inflammatory bowel disease (IBD). However, the role of Th17 cells in psoriasis has not been clarified completely. Th17-derived proinflammatory cytokines including IL-17A, IL-17F, IL-21, IL-22, and IL-26 have a critical role in the pathogenesis of these disorders. In this review, we introduced the signaling and transcriptional regulation of Th17 cells. And then, we demonstrate the immunopathology role of Th17 cells and functions of the related cytokines in the psoriasis to get a better understanding of the inflammatory mechanisms mediated by Th17 cells in this disease.

Psoriasis Among Adolescents in Kuwait and the Role of Siblings, Breastfeeding, and Household Cat and Secondhand Smoke Exposure: A Cross-Sectional Study

INTRODUCTION

Globally, the epidemiology of psoriasis is poorly understood, and most countries lack essential epidemiologic data regarding disease burden and its determinants. This study sought to estimate the prevalence of psoriasis among adolescents in Kuwait and assess its association with different risk factors, including obesity, sibship size, breastfeeding, and exposure to household secondhand smoke (SHS) and pets.

METHODS

Schoolchildren aged 11-14 years (n = 3864) were enrolled in a cross-sectional study. Lifetime and current (past 12 months) prevalence of psoriasis were ascertained according to ever having a history of doctor-diagnosis plus current active lesion(s) and/or current use of treatment of psoriasis. Associations were assessed using Poisson regression with robust variance estimation, and adjusted prevalence ratios (aPR) and 95% confidence intervals (CI) were estimated.

RESULTS

The lifetime and current prevalence of psoriasis were estimated to be 3.6% (136/3806) and 1.1% (42/3806), respectively. Commonly reported anatomical sites affected by psoriasis included scalp (47.6%) and the extensor surface of the knees (50%) and elbows (38.1%). Household SHS exposure was associated with increased lifetime psoriasis (aPR = 1.41, 95% CI 1.07-1.98), and showed a trend for association with current psoriasis (1.77, 0.89-3.53). Similarly, cat-keeping during infancy was associated with lifetime psoriasis (1.96, 1.14-3.37), and demonstrated a trend for association with current psoriasis (1.49, 0.52-1.98). In contrast, breastfeeding was associated with a decreased lifetime psoriasis (0.62, 0.44-0.89), but was not associated with current psoriasis. Trend analyses showed that the prevalence of lifetime and current psoriasis increased with increasing numbers of total, older, and younger siblings.

CONCLUSIONS

Psoriasis affects a considerable proportion of schoolchildren in Kuwait. Interestingly, psoriasis prevalence was related to risk factors also found in allergic diseases, such as exposure to SHS, cat-keeping in infancy, breastfeeding, and sibship size, possibly suggesting a role of immune dysregulation.

A monocyte-keratinocyte-derived co-culture assay accurately identifies efficacies of BET inhibitors as therapeutic candidates for psoriasiform dermatitis

BACKGROUND

Bromodomain and extra-terminal (BET) proteins perform key roles in epigenetic control of gene expression that is involved in inflammatory conditions, including psoriasiform dermatitis (PsD). Predicting which (of many potential available BET inhibitors) will be effective in vivo is challenging.

OBJECTIVE

We determine if a novel in vitro assay that includes two critical cell types involved in human psoriasis can predict the therapeutic potential of specific BET inhibitors in vivo.

METHODS

An in vitro model consisting of U-937 and HaCaT cell co-culture was created to screen small molecule BET antagonists for inhibition of cutaneous inflammatory genes. Efficacious BET inhibitors were tested in a mouse imiquimod (IMQ)-induced PsD model.

RESULTS

In the co-culture system, HaCaT cells exhibited a marked increase in the secretion of a characteristic set of proinflammatory and Th17-associated cytokines. Of the ten commercially-available small molecules targeting BET proteins assayed, most compounds exhibited inhibitory functions at 1 μM against inflammatory activation, but responded variably at lower concentrations. OTX015, a typical representative for most of the compounds, barely inhibited the inflammatory reactions at 0.1 μM. By contrast, ABBV075 was effective in concentrations as low as 0.01 μM. While oral administration OTX015 in IMQ-treated mice reduced disease severity, ABBV075 equally decreased the symptoms and molecular and cellular severity markers at one-tenth of the minimal dosing required for OTX015.

CONCLUSION

In vitro screening system combined with an in vivo animal model, can serve as a convenient pre-clinical screening tool for the selection of BET inhibitors (and possibly other drugs) that may have clinical potential in psoriasis therapy.

A Tissue-Engineered Human Psoriatic Skin Model to Investigate the Implication of cAMP in Psoriasis: Differential Impacts of Cholera Toxin and Isoproterenol on cAMP Levels of the Epidermis

Pathological and healthy skin models were reconstructed using similar culture conditions according to well-known tissue engineering protocols. For both models, cyclic nucleotide enhancers were used as additives to promote keratinocytes’ proliferation. Cholera toxin (CT) and isoproterenol (ISO), a beta-adrenergic agonist, are the most common cAMP stimulators recommended for cell culture. The aim of this study was to evaluate the impact of either CT or ISO on the pathological characteristics of the dermatosis while producing a psoriatic skin model. Healthy and psoriatic skin substitutes were produced according to the self-assembly method of tissue engineering, using culture media supplemented with either CT (10⁻¹⁰ M) or ISO (10⁻⁶ M). Psoriatic substitutes produced with CT exhibited a more pronounced psoriatic phenotype than those produced with ISO. Indeed, the psoriatic substitutes produced with CT had the thickest epidermis, as well as contained the most proliferating cells and the most altered expression of involucrin, filaggrin, and keratin 10. Of the four conditions under study, psoriatic substitutes produced with CT had the highest levels of cAMP and enhanced expression of adenylate cyclase 9. Taken together, these results suggest that high levels of cAMP are linked to a stronger psoriatic phenotype.

Lysophosphatidic Acid Receptor 5 Contributes to Imiquimod-Induced Psoriasis-Like Lesions through NLRP3 Inflammasome Activation in Macrophages

The pathogenesis of psoriasis, an immune-mediated chronic skin barrier disease, is not fully understood yet. Here, we identified lysophosphatidic acid (LPA) receptor 5 (LPA₅)-mediated signaling as a novel pathogenic factor in psoriasis using an imiquimod-induced psoriasis mouse model. Amounts of most LPA species were markedly elevated in injured skin of psoriasis mice, along with LPA₅ upregulation in injured skin. Suppressing the activity of LPA₅ with TCLPA5, a selective LPA₅ antagonist, improved psoriasis symptoms, including ear thickening, skin erythema, and skin scaling in imiquimod-challenged mice. TCLPA5 administration attenuated dermal infiltration of macrophages that were found as the major cell type for LPA₅ upregulation in psoriasis lesions. Notably, TCLPA5 administration attenuated the upregulation of macrophage NLRP3 in injured skin of mice with imiquimod-induced psoriasis. This critical role of LPA₅ in macrophage NLRP3 was further addressed using lipopolysaccharide-primed bone marrow-derived macrophages. LPA exposure activated NLRP3 inflammasome in lipopolysaccharide-primed cells, which was evidenced by NLRP3 upregulation, caspase-1 activation, and IL-1β maturation/secretion. This LPA-driven NLRP3 inflammasome activation in lipopolysaccharide-primed cells was significantly attenuated upon LPA₅ knockdown. Overall, our findings establish a pathogenic role of LPA₅ in psoriasis along with an underlying mechanism, further suggesting LPA₅ antagonism as a potential strategy to treat psoriasis.

miR-183-3p suppresses proliferation and migration of keratinocyte in psoriasis by inhibiting GAB1

Background

MicroRNAs (miRNAs) target genes involved in the hyperproliferation of keratinocytes or immune dysfunction of psoriasis. This study prospectively determined the involvement of miR-183-3p in the pathogenesis of psoriasis.

Methods

Differentially expressed miR-183-3p between psoriatic lesional and non-lesional skin were determined by quantitative RT-PCR and in situ hybridization (ISH). CCK8 and wound healing assays were performed to assess cell viability and migration of human keratinocyte cell line (HaCaT). The target of miR-183-3p was validated by luciferase activity assay.

Results

Lower miR-183-3p expression was observed in psoriatic lesional skin compared to psoriatic non-lesional skin. MiR-183-3p over-expression inhibited the viability and migration of HaCaT cells, while inhibition of miR-183-3p promoted the viability and migration of HaCaT cells. Moreover, miR-183-3p could bind to the 3′ UTR of GAB1 (growth factor receptor binding 2-associated binding protein 1) and decrease the mRNA and protein expression of GAB1 in HaCaT cells. In addition, higher GAB1 expression was observed in psoriatic lesional skin than psoriatic non-lesional skin.

Conclusion

MiR-183-3p exhibited inhibition property in the proliferation and migration of HaCaT cells via down-regulation of GAB1, suggesting the potential therapeutic strategy for psoriasis.

Investigation on the Mechanism of Qubi Formula in Treating Psoriasis Based on Network Pharmacology

Objective

To elucidate the pharmacological mechanisms of Qubi Formula (QBF), a traditional Chinese medicine (TCM) formula which has been demonstrated as an effective therapy for psoriasis in China.

Methods

The Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, BATMAN-TCM database, and literature search were used to excavate the pharmacologically active ingredients of QBF and to predict the potential targets. Psoriasis-related targets were obtained from Therapeutic Target Database (TTD), DrugBank database (DBD), MalaCards database, and DisGeNET database. Then, we established the network concerning the interactions of potential targets of QBF with well-known psoriasis-related targets by using protein-protein interaction (PPI) data in String database. Afterwards, topological parameters (including DNMC, Degree, Closeness, and Betweenness) were calculated to excavate the core targets of Qubi Formula in treating psoriasis (main targets in the PPI network). Cytoscape was used to construct the ingredients-targets core network for Qubi Formula in treating psoriasis, and ClueGO was used to perform GO-BP and KEGG pathway enrichment analysis on these core targets.

Results

The ingredient-target-disease core network of QBF in treating psoriasis was screened to contain 175 active ingredients, which corresponded to 27 core targets. Additionally, enrichment analysis suggested that targets of QBF in treating psoriasis were mainly clustered into multiple biological processes (associated with nuclear translocation of proteins, cellular response to multiple stimuli (immunoinflammatory factors, oxidative stress, and nutrient substance), lymphocyte activation, regulation of cyclase activity, cell-cell adhesion, and cell death) and related pathways (VEGF, JAK-STAT, TLRs, NF-κB, and lymphocyte differentiation-related pathways), indicating the underlying mechanisms of QBF on psoriasis.

Conclusion

In this work, we have successfully illuminated that Qubi Formula could relieve a wide variety of pathological factors (such as inflammatory infiltration and abnormal angiogenesis) of psoriasis in a "multicompound, multitarget, and multipathway" manner by using network pharmacology. Moreover, our present outcomes might shed light on the further clinical application of QBF on psoriasis treatment.

Pleiotropic Role of Notch Signaling in Human Skin Diseases

Notch signaling orchestrates the regulation of cell proliferation, differentiation, migration and apoptosis of epidermal cells by strictly interacting with other cellular pathways. Any disruption of Notch signaling, either due to direct mutations or to an aberrant regulation of genes involved in the signaling route, might lead to both hyper- or hypo-activation of Notch signaling molecules and of target genes, ultimately inducing the onset of skin diseases. The mechanisms through which Notch contributes to the pathogenesis of skin diseases are multiple and still not fully understood. So far, Notch signaling alterations have been reported for five human skin diseases, suggesting the involvement of Notch in their pathogenesis: Hidradenitis Suppurativa, Dowling Degos Disease, Adams-Oliver Syndrome, Psoriasis and Atopic Dermatitis. In this review, we aim at describing the role of Notch signaling in the skin, particularly focusing on the principal consequences associated with its alterations in these five human skin diseases, in order to reorganize the current knowledge and to identify potential cellular mechanisms in common between these pathologies.

Topical application of endothelin receptor a antagonist attenuates imiquimod-induced psoriasiform skin inflammation

Endothelin-1 (ET-1) is well known as the most potent vasoconstrictor, and can evoke histamine-independent pruritus. Recently, its involvement in cutaneous inflammation has begun to draw attention. The upregulation of ET-1 expression in the epidermis of human psoriasis patients has been reported. It was also demonstrated that ET-1 can stimulate dendritic cells to induce Th17/1 immune responses. However, the role of the interaction between ET-1 and ET-1 receptors in the pathogenesis of psoriasis remains elusive. Here, we investigated the effects of ET-1 receptor antagonist on imiquimod (IMQ) -induced psoriasiform dermatitis in mouse. Psoriasis-related cytokines such as IL-17A and TNF-α induced ET-1 expression in human keratinocytes. Topical application of selective endothelin A receptor (ETAR) antagonist ambrisentan significantly attenuated the development of IMQ-induced psoriasiform dermatitis and also significantly inhibited the histological inflammation and cytokine expression (TNF-α, IL-12p40, IL-12 p19, and IL-17) in the lesional skin of the mouse model. Furthermore, topical application of ambrisentan suppressed phenotypic and functional activation of dendritic cells in lymph nodes. Our findings indicate that the ET-1 and ETAR axis plays an important role in the pathogenesis of psoriasis and is a potential therapeutic target for treating psoriasis.

Oncostatin M upregulates Livin to promote keratinocyte proliferation and survival via ERK and STAT3 signalling pathways

NEW FINDINGS

What is the central question of this study? What controls the proliferation and apoptosis in the pathogenesis of psoriasis? What is the main finding and its importance? The pathogenesis psoriasis involves abnormal homeostasis of keratinocytes, with hyperproliferation and decreasing apoptosis. An inhibitor of apoptosis protein family molecule, Livin, is highly expressed in psoriasis vulgaris lesional skin tissue. Expression of Livin was upregulated at transcription and protein levels after stimulation with oncostatin M (OSM). OSM promoted the survival of HaCaT cells in oxidative stress conditions. Expression of Livin and proliferation of HaCaT cells stimulated by OSM was regulated through ERK and STAT3 signalling pathways. This study might provide new insights into targeted therapy for psoriasis.

ABSTRACT

Psoriasis is an immune-mediated chronic inflammatory disease. Abnormal homeostasis of keratinocytes, with hyperproliferation and decreasing apoptosis, is involved in the pathogenesis of psoriasis. Here, we report that an inhibitor of apoptosis protein family molecule, Livin, is highly expressed in psoriasis vulgaris lesional skin tissue at transcription and protein levels. Importantly, the expression level of Livin is related to the severity of psoriasis. The aim of the study was to investigate the regulation and functions of Livin in keratinocytes stimulated by the pro-inflammatory cytokine oncostatin M (OSM). The expression of Livin in HaCaT cells at mRNA and protein levels was measured by real-time PCR and Western blotting after OSM stimulation. The cell proliferation was measured by a 5-ethynyl-2'-deoxyuridine incorporation assay. Cell death was induced by the exogenous hydrogen peroxide (H₂ O₂ ) stress model, detected by 7-amino-actinomycin D staining and analysed by flow cytometry. Livin was overexpressed by a lentiviral transduction system to validate the roles of OSM and Livin in HaCaT cells. Specific inhibitors of ERK (U0126) and STAT3 (cryptotanshinone) were applied to investigate the signalling pathways involved in the regulation of Livin expression by OSM. The expression of Livin was upregulated after stimulation with OSM. OSM promoted the proliferation and survival of HaCaT cells. The expression of Livin and the proliferation of HaCaT cells induced by OSM were regulated through the ERK and STAT3 signalling pathways. We conclude that OSM promotes HaCaT cell proliferation and survival in conditions of oxidative stress.

To explore the clinical efficacy of Traditional Chinese Medicine bath in the treatment of psoriasis vulgaris with blood-heat syndrome and its effect on related cytokines based on different temperature and different concentration

BACKGROUND

Chinese herbal bath has long been used in the curative treatment of psoriasis vulgaris. However, there is no unified standard protocol for Chinese herbal bath. Many factors affect the curative effect of Chinese herbal bath, such as water temperature, bath concentration, and soaking time. Most studies involving Chinese herbal bath has described the bath generally, and few studies have investigated the factors that might contribute to the efficacy of Chinese herbal bath. Here we describe a protocol to evaluate the efficacy and safety of various bathwater temperatures and herbal concentrations on psoriasis vulgaris, and their effect on serum vascular endothelial growth factor (VEGF), tumor necrosis factor α (TNF-α), interleukin 23 (IL-23), and interleukin 17 (IL-17). These data could be useful for optimizing Chinese herbal bath treatments.

METHODS

In this randomized controlled trial, we planned to recruit 288 hospitalized atients with psoriasis vulgaris aged 18 to 65 years. All participants who meet the inclusion criteria will be randomly assigned to the observation group, the control group, or the basic treatment group. The observation group will be divided into 6 sub-groups according to water temperatures and bath concentrations, designated as observation groups 1 to 6. Thirty-six participants will be assigned to each group. The basic treatment group will be given co-qingdai capsule, po 2 g tid; compound glycyrrhizin tablet, po 75 mg tid; AA Skincare jojoba Oil, us.ext qd. The observation group will be given a Chinese herbal bath at the same time as the basic treatment. The control group will be given ozone hydrotherapy at the same time as the basic treatment. The entire treatment course will last for 2 weeks. The following parameters will be compared in each group, before and 2 weeks after treatment: the psoriasis area and severity index score (PASI), pruritus score, clinical efficacy, and dermatology life quality index score (DLQI); serum levels of serum VEGF, TNF-α, IL-23, and IL-17; and confocal laser scanning microscope images.

CONCLUSION

This study will evaluate the efficacy and safety of various Chinese herbal bath conditions (water temperatures and herbal concentrations) on the treatment of psoriasis vulgaris, which will provide an important reference for the operation of Chinese herbal bath.

TRIAL REGISTRATION NUMBER

ChiCTR1900027468.

Current Developments in the Immunology of Psoriasis

Psoriasis is a frequent inflammatory skin disease. Fundamental research on the pathogenesis of psoriasis has substantially increased our understanding of skin immunology, which has helped to introduce innovative and highly effective therapies. Psoriasis is a largely T lymphocyte-mediated disease in which activation of innate immune cells and pathogenic T cells result in skin inflammation and hyperproliferation of keratinocytes. B cells have thus far largely been neglected regarding their role for the pathogenesis of psoriasis. However, recent data shed light on their role in inflammatory skin diseases. Interestingly, interleukin (IL)-10-producing regulatory B cells have been assumed to ameliorate psoriasis. In this review, we will discuss the development of disease, pathogenicity, and current developments in therapeutic options. We describe different roles of T cells, B cells, and cytokines for the immunopathology and disease course of psoriasis.

The Brain-Skin Connection and the Pathogenesis of Psoriasis: A Review with a Focus on the Serotonergic System

Psoriasis is a common non-communicable chronic immune-mediated skin disease, affecting approximately 125 million people in the world. Its pathogenesis results from a combination of genetic and environmental factors. The pathogenesis of psoriasis seems to be driven by the interaction between innate immune cells, adaptive immune cells and keratinocytes, in a process mediated by cytokines (including interleukins (IL)-6, IL-17 and IL-22, interferon and tumor necrosis factor) and other signaling molecules. This leads to an inflammatory process with increased proliferation of epidermal cells, neo-angiogenesis and infiltration of dendritic cells in the skin. Dysfunctional de novo glucocorticoid synthesis in psoriatic keratinocytes and the skin microbiome have also been suggested as mediators in the pathogenesis of this disease. To understand psoriasis, it is essential to comprehend the processes underlying the skin immunity and neuroendocrinology. This review paper focuses on the skin as a neuroendocrine organ and summarizes what is known about the skin immune system, the brain-skin connection and the role played by the serotonergic system in skin. Subsequently, the alterations of neuroimmune processes and of the serotonergic system in psoriatic skin are discussed, as well as, briefly, the genetic basis of psoriasis.

Reduced Efficacy of Biological Drugs in Psoriatic Patients with HLA-A Bw4-80I KIR Ligands

BACKGROUND

Biological drugs (biologics) are a highly effective therapy for the moderate to severe form of psoriasis, an immune-mediated dermatosis with a strong immunogenetic component. The interaction between human leukocyte antigen (HLA) class I ligands and killer immunoglobulin-like receptors (KIR) has a functional significance in the education of natural killer (NK) cells, and can thus influence the response to biologics.

OBJECTIVE

In this study, we investigated the impact of HLA-A and -B KIR ligands in the response to biologics in a cohort of psoriatic patients.

METHODS

Eighty-five patients with moderate to severe psoriasis treated with biologics (adalimumab, etanercept, infliximab, ustekinumab and secukinumab) were enrolled in the study. Clinical response was evaluated as patients attaining 50%, 75% or 90% reduction in the Psoriasis Area and Severity Index (PASI) (PASI 50, 75 or 90, respectively) over 6 months' follow-up. Poor response was defined as PASI 50, and in this case patients shifted to treatment with a different biologic. Fifty-two patients (61.2%) showed excellent response (PASI 90) to the first biologic, while 33 patients (38.8%), needed two or more biologics before reaching an excellent response (PASI 90) and were considered difficult to treat.

RESULTS

Only HLA-A Bw4-80I ligands were associated with the response to biologics; in particular, they were linked with reduced response both at univariable analysis (odds ratio [OR] 3.11, 95% confidence interval [CI] 1.19-8.07; p = 0.019) and multivariable analysis (OR 5.02, 95% CI 1.40-17.97; p = 0.013).

CONCLUSION

We suggest that the HLA-A Bw4-80I epitope could be a marker of reduced responsiveness to biologics. The possible reason for this is an increase of tumour necrosis factor (TNF)-α and the silencing of NK cells through the predominant interaction with the KIR3DL/S pair. HLA-KIR affinities might lead to a more efficient way to prescribe biologics.

Keratinocyte: A trigger or an executor of psoriasis?

Psoriasis is a common chronic inflammatory skin disease characterized by abnormal proliferation/differentiation of keratinocytes and excessive immune cell infiltration in the dermis and epidermis. Over the past 2 decades, immune cells have been considered as the main driver of psoriasis because the neutralizing antibodies targeting the IL-23/IL-17 axis that regulates cross-talk between dendritic cells and T cells achieve tremendous success in the treatment of psoriasis. However, whether keratinocyte would be a driver of psoriasis or just an executor in response to immune cells is still under debate. In this review, we focus on the recent advances in the identification of keratinocyte as a trigger of psoriasis, summarize on the role of keratinocytes in self-perpetuating loop to maintain inflammation in psoriasis, and then discuss the possible roles of keratinocytes in the relapse of psoriasis.

Carotenoids from Cyanobacteria: A Biotechnological Approach for the Topical Treatment of Psoriasis

In this study, five cyanobacteria strains (Alkalinema aff. pantanalense LEGE15481, Cyanobium gracile LEGE12431, Nodosilinea (Leptolyngbya) antarctica LEGE13457, Cuspidothrix issatschenkoi LEGE03282 and Leptolyngbya-like sp. LEGE13412) from the Blue Biotechnology and Ecotoxicology Culture Collection (LEGE CC) of CIIMAR were explored for their biotechnological potential in the treatment of psoriasis. Different extracts were characterized for their pigment profile by HPLC-PDA. The antioxidant potential of the extracts was assessed against the superoxide anion radical (O₂^•-). Their anti-inflammatory and antiproliferative potential was assessed in vitro using the macrophages RAW 264.7 and the human keratinocytes HaCaT as cell-line models, respectively. Terrestrial and freshwater strains presented the highest carotenoid content (33193-63926 μg/g dry extract), with all-trans-β-carotene, zeaxanthin, echinenone and lutein derivatives being the most abundant carotenoids. Acetone was the most effective solvent for pigment extraction. The acetone extracts presented the lowest IC₅₀ values (0.29-0.38 mg dry extract/mL) regarding O₂^•- scavenging, and revealed anti-inflammatory potential, with N. antarctica LEGE13457, A. pantanalense LEGE15481 and Leptolyngbya-like sp. LEGE13412 reducing the nitric oxide (NO) in RAW 264.7 cell culture medium in about 25% (p < 0.05). With the exception of A. pantanalense LEGE15481, all the extracts significantly reduced keratinocyte proliferation (p < 0.05), demonstrating a selective toxicity among the different cell lines. Overall, Leptolyngbya-like sp. LEGE13412 and N. antarctica LEGE13457 seem promising for further exploitation in the framework of psoriasis, due to their antioxidant, anti-inflammatory and antiproliferative potential.

Inhibition of keratinocyte necroptosis mediated by RIPK1/RIPK3/MLKL provides a protective effect against psoriatic inflammation

Psoriasis is a common autoimmune and chronic inflammatory skin disorder globally affecting 0.51–11.43% of adults. Inflammation-associated cell death in keratinocytes plays a key role in the process of integrate inflammatory cascade in psoriasis. Necroptosis is a regulated necrotic cell death mediated by receptor interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like pseudokinase (MLKL), which participates in many human inflammatory diseases. However, the mechanism and function of programmed necrosis in psoriasis is not well-illustrated. In the current study, we provide evidence for the involvement of necroptosis in psoriasis. RIPK1 and MLKL were significantly upregulated and localized in all layers of the epidermis in human psoriatic lesions, while RIPK3 and phosphorylated MLKL were mainly expressed in keratinocytes, which located in the upper layers. Increased tendency of necroptosis was also found in IMQ-induced psoriasiform skin of mice. Further, we discovered that both the inhibitor of RIPK1 R-7-Cl-O-Necrostatin-1 (Nec-1s) and MLKL-inhibitor necrosulfonamide (NSA) suppressed necroptosis in HaCaT cells and IMQ mouse models, powerfully blocked IMQ-induced inflammatory responses in vivo, and significantly downregulated the production of inflammatory factors like IL-1β, IL-6, IL-17A, IL-23a, CXCL1, and CCL20. These findings promote the development of new therapies for the treatment of necroptosis-activated pathologies for psoriasis.

TET2 is involved in DNA hydroxymethylation, cell proliferation and inflammatory response in keratinocytes

DNA methylation and hydroxymethylation are the most common epigenetic modifications associated with the cell cycle and the inflammatory response. The present study aimed to investigate the role of 5-hydroxymethyl-cytosine (5-hmC) and ten-eleven translocation-2 (TET2) in keratinocytes. Following TET2 knockdown, dot blot analysis was performed to assess the levels of 5-hmC in keratinocytes, using HaCaT cells. Subsequently, the viability and cell cycle of HaCaT cells were assessed by MTT, Cell Counting Kit-8 assay and flow cytometric assays. Cyclin-dependent kinase inhibitor 2A and proinflammatory cytokine protein and mRNA expression levels were also detected. The present results suggested that TET2 may play an important role in regulating cellular proliferation by mediating DNA hydroxymethylation in HaCaT cells. In addition, TET2 knockdown decreased the production of proinflammatory cytokines, including lipocalin 2, S100 calcium binding protein A7, matrix metallopeptidase 9, C-X-C motif chemokine ligand 1, interferon regulatory factor 7 and interleukin-7 receptor. The present study suggested that TET2 regulated cell viability, apoptosis and the expression of inflammatory mediators in keratinocytes. Collectively, the results indicated that TET2 knockdown may relieve inflammatory responses in the skin.

Acupuncture Needling, Electroacupuncture, and Fire Needling Improve Imiquimod-Induced Psoriasis-Like Skin Lesions through Reducing Local Inflammatory Responses

Psoriasis is a common autoimmune disease. Acupuncture-related techniques have been widely used to treat psoriasis since its ability to engage neuronal function, the immune system, and other systems is well documented. This study aimed to investigate and compare the effects of three common acupuncture-related techniques in psoriasis-like skin inflammatory responses and explore the possible involved mechanisms. Imiquimod (IMQ)-induced psoriasis-like mice were treated with acupuncture needling, electroacupuncture, or fire acupuncture. Methotrexate (MTX) was applied as a positive control. Scoring by the psoriasis area and severity index (PASI) evaluated skin lesion changes. Keratinocyte proliferation and inflammatory cell infiltration were investigated using pathological staining. The secretion levels of inflammatory cytokines were detected by enzyme-linked immunosorbent assay. The expression levels of neuropeptides were assessed by Western immunoblotting. We found that acupuncture needling, electroacupuncture, and fire acupuncture all ameliorated skin lesions, reduced epidermal thickness, inhibited keratinocyte proliferation, and reduced CD3⁺ T cell infiltration. The aforementioned acupuncture techniques also decreased inflammatory cytokine secretion, including IL-1β, IL-17A, and IL-23p40. Among them, electroacupuncture showed the best curative effects. Additionally, electroacupuncture downregulated the expression levels of Neurokinin A (NKA), which was positively associated with decreased inflammatory cytokine levels in local lesions. In conclusion, acupuncture needling, electroacupuncture, and fire acupuncture alleviated IMQ-induced psoriasis-like lesions. By contrast, electroacupuncture was more beneficial in reducing the inflammatory response, which might be related to locally dampened neuropeptide levels. Observations support the therapeutic effect of acupuncture for psoriasis and indicate a neuromodulatory mechanism in treating psoriasis by electroacupuncture.

Ginsenoside compound K ameliorates imiquimod-induced psoriasis-like dermatitis through inhibiting REG3A/RegIIIγ expression in keratinocytes

BACKGROUND

Psoriasis is a chronic inflammatory skin disease characterized by keratinocyte hyperproliferation. Ginsenoside compound K (CK), a bioactive metabolite of ginseng, modulates various skin disorders with an impact on keratinocyte biology. However, the effect of Ginsenoside CK in psoriasis has not been explored.

OBJECTIVE

Our aim was to investigate whether ginsenoside CK could affect the homeostasis of keratinocytes and their expression of psoriasis-associated antimicrobial protein regenerating islet-derived protein 3-alpha (REG3A) and its murine ortholog RegIIIγ. We further explored the therapeutic potential of ginsenoside CK in imiquimod (IMQ)-induced psoriasis-like dermatitis.

METHODS

The effects of ginsenoside CK in cell growth and apoptosis of human keratinocytes were measured by MTT assay and flow cytometry, respectively. Bax levels were evaluated by Western blot in HaCaT cells following ginsenoside CK stimulation. REG3A levels were assessed by RT-PCR and Western blot in human keratinocytes following interleukin (IL)-36γ and ginsenoside CK co-simulation. Utilizing IMQ-induced psoriasis mouse model, the therapeutic effects of 0.1% and 1% ginsenoside CK cream were assessed by skin thicknesses and histological examinations, and RegIIIγ level in the lesional skin was detected by Western blot and immunofluorescence.

RESULTS

Ginsenoside CK prohibited human keratinocyte proliferation but did not affect their apoptosis. Moreover, it inhibited IL-36γ-induced REG3A expression in HaCaT cells. Ginsenoside CK alleviated imiquimod-induced psoriasis-like hyperkeratosis and reduced RegIIIγ expression in the keratinocytes from lesional skin.

CONCLUSION

Ginsenoside CK ameliorated IMQ-induced psoriasis-like dermatitis possibly through inhibiting REG3A/RegIIIγ expression in keratinocytes, which highlighted a therapeutic potential of ginsenoside CK in psoriasis.

The role of invariant T cells in inflammation of the skin and airways

Invariant and semi-invariant T cells are emerging as important regulators of host environment interactions at barrier tissues such as the airway and skin. In contrast to conventional T cells, invariant natural killer T (iNKT) cells and mucosal associated invariant T (MAIT) cells express T cell receptors of very limited diversity. iNKT and MAIT cells recognise antigens presented by the MHC class 1-like monomorphic molecules CD1d and MR1, respectively. Both iNKT cells and MAIT cells have been identified in the skin and airways and can rapidly produce cytokines after activation. Numerous studies have implicated iNKT cells in the pathology of both skin and airway disease, but conflicting evidence in human disease means that more studies are necessary to resolve the exact roles of iNKT in inflammation. The functions of MAIT cells in skin and lung inflammation are even less well defined. We herein describe the current literature on iNKT and MAIT cells in allergic and non-allergic skin diseases (dermatitis and psoriasis) and airway diseases (asthma, chronic obstructive pulmonary disease, rhinitis, and chronic rhinosinusitis).

Cannabinoid Signaling in the Skin: Therapeutic Potential of the "C(ut)annabinoid" System

The endocannabinoid system (ECS) has lately been proven to be an important, multifaceted homeostatic regulator, which influences a wide-variety of physiological processes all over the body. Its members, the endocannabinoids (eCBs; e.g., anandamide), the eCB-responsive receptors (e.g., CB₁, CB₂), as well as the complex enzyme and transporter apparatus involved in the metabolism of the ligands were shown to be expressed in several tissues, including the skin. Although the best studied functions over the ECS are related to the central nervous system and to immune processes, experimental efforts over the last two decades have unambiguously confirmed that cutaneous cannabinoid ("c[ut]annabinoid") signaling is deeply involved in the maintenance of skin homeostasis, barrier formation and regeneration, and its dysregulation was implicated to contribute to several highly prevalent diseases and disorders, e.g., atopic dermatitis, psoriasis, scleroderma, acne, hair growth and pigmentation disorders, keratin diseases, various tumors, and itch. The current review aims to give an overview of the available skin-relevant endo- and phytocannabinoid literature with a special emphasis on the putative translational potential, and to highlight promising future research directions as well as existing challenges.