Psoriasis: Behind the scenes

Autoreactive T-Cells in Psoriasis: Are They Spoiled Tregs and Can Therapies Restore Their Functions?

Psoriasis is a chronic inflammatory skin disease, which affects 2-4% of the population worldwide. T-cell derived factors such as Th17 and Th1 cytokines or cytokines such as IL-23, which favors Th17-expansion/differentiation, dominate in the disease. Therapies targeting these factors have been developed over the years. An autoimmune component is present, as autoreactive T-cells specific for keratins, the antimicrobial peptide LL37 and ADAMTSL5 have been described. Both autoreactive CD4 and CD8 T-cells exist, produce pathogenic cytokines, and correlate with disease activity. Along with the assumption that psoriasis is a T-cell-driven disease, Tregs have been studied extensively over the years, both in the skin and in circulation. This narrative review resumes the main findings about Tregs in psoriasis. We discuss how Tregs increase in psoriasis but are impaired in their regulatory/suppressive function. We debate the possibility that Tregs convert into T-effector cells under inflammatory conditions; for instance, they may turn into Th17-cells. We put particular emphasis on therapies that seem to counteract this conversion. We have enriched this review with an experimental section analyzing T-cells specific for the autoantigen LL37 in a healthy subject, suggesting that a shared specificity may exist between Tregs and autoreactive responder T-cells. This suggests that successful psoriasis treatments may, among other effects, restore Tregs numbers and functions.

Annoying Psoriasis and Atopic Dermatitis: A Narrative Review

Skin is an important organ that mainly functions as a barrier. Skin diseases can damage a person's self-confidence and reduce their willingness to socialize, as well as their social behavior and willingness. When the skin appearance is abnormal, in addition to affecting the quality of life, it often leads to personal, social, and psychological dysfunction and even induces depression. Psoriasis and atopic dermatitis are common chronic skin diseases. Their prevalence in the world is 3-10%, and there is an increasing trend year by year. These congenital or acquired factors cause the dysfunction of the immune system and then destroy the barrier function of the skin. Because these patients are flooded with a variety of inflammatory mediators, this causes skin cells to be in chronic inflammation. Therefore, psoriasis and atopic dermatitis are also considered systemic chronic inflammatory diseases. In the healthcare systems of developed countries, it is unavoidable to spend high costs to relieve symptoms of psoriasis and atopic dermatitis patients, because psoriasis and atopic dermatitis have a great influence on individuals and society. Giving a lot of attention and developing effective treatment methods are the topics that the medical community must work on together. Therefore, we used a narrative review manuscript to discuss pathogenesis, clinical classification, incidence, and treatment options, including topical medication, systemic therapeutics, immunosuppressive medication for psoriasis, and atopic dermatitis, as well as also comparing the differences between these two diseases. We look forward to providing readers with comprehensive information on psoriasis and atopic dermatitis through this review article.

Effects of Qingre Huoxue Jiedu Formula on Nerve Growth Factor-Induced Psoriasis

OBJECTIVE

To elucidate the mechanisms of 4 effective components from a Chinese medicine formula, namely Qingre Huoxue Jiedu Formula (QHJ heat- and toxin-clearing and blood-activating formula), in the treatment of nerve growth factor (NGF)-induced psoriasis.

METHODS

Keratinocyte proliferation and T cell proliferation models were developed using NGF. An NGF solution (NGF+DMEM, 100 ng/mL) was added to all induced groups and treated groups and were cultured for 24 h, while a solution with NTRK1 antagonist (K252a+DEME, 300 nmol/L) was added and cultured for 1 h. The models were used to evaluate the effects of the treatment with each of the 4 components of QHJ, namely shikonin, paeonol, astilbin and ursolic acid. Cell apoptosis and proliferation were measured by flow cytometry analysis and CCK8 assay, respectively. The mRNA expression levels of Bax, Bcl-xl, and NGF receptor (NGFR) were assessed by quantitative real-time PCR (qRT-PCR) and Western blot analysis, respectively.

RESULTS

(1) All QHJ-treated groups showed significantly increased cell apoptosis and inhibition of cell proliferation compared with the NGF-induced groups (P<0.05). In addition, treatment with QHJ plus NTRK1 significantly enhanced cell apoptosis and inhibition of cell proliferation compared with cells treated with QHJ only (P<0.05), particularly in cells treated with ursolic acid. (2) QHJ-treated groups showed higher protein expression levels of Bax, Bcl-xl compared with other groups (P<0.05). Additionally, treatment with QHJ plus NTRK1 significantly increased the protein expression levels of Bax, Bcl-xl and NGFR compared with those treated with QHJ only (all P<0.05), especially in those treated with shikonin.

CONCLUSION

The action mechanism of QHJ on psoriasis might be through enhancing cell apoptosis and inhibition of cell proliferation, and upregulating the expression level of Bax, Bcl-xl and NGFR.

Downregulation of interleukin 36γ and its cleaver cathepsin G following treatment with narrow-band ultraviolet B phototherapy in psoriasis vulgaris

BACKGROUND

Growing evidence suggests the important role of IL-36 in the pathogenesis of psoriasis. Cathepsin G is a neutrophil-derived protease that can activate IL-36γ.

OBJECTIVE

To assess the expression of IL-36γ and cathepsin G in psoriasis and to quantify the impact of treatment with narrow-band ultraviolet B phototherapy (NB-UVB) on their levels.

METHODS

This case-control study involved 26 patients with moderate-severe psoriasis and 25 healthy volunteers. Psoriasis patients eligible for phototherapy received 24 NB-UVB sessions. Punch skin biopsies were obtained from all participants at recruitment and after phototherapy from patients. Real-time PCR was utilized for quantitative assessment of IL-36γ and cathepsin G expression in tissue samples.

RESULTS

The expression of IL-36γ and cathepsin G was significantly higher in psoriasis before NB-UVB therapy compared to controls (p < .001). Both proteins decreased significantly with clinical improvement following NB-UVB therapy compared to baseline (p < .001). However, their expression after treatment was still higher than controls (p < .001).

CONCLUSION

IL-36γ and cathepsin G expression is upregulated in psoriatic lesions, supporting their role as mediators of inflammation in psoriasis. Downregulation of IL-36γ and cathepsin G is a possible mechanism for psoriasis improvement after NB-UVB therapy. IL-36 and cathepsin G can be considered as therapeutic targets for psoriasis.

Saudi consensus statement on biologic treatment of chronic plaque psoriasis (2020)

Psoriasis is a common chronic and complex inflammatory skin disease that affects over 125 million people worldwide. Management of psoriasis in daily clinical practice in Saudi Arabia is variable. Local preferences for management differ, which may have a bearing on the treatment selection. Biologic therapy is now a well-established strategy for managing moderate-to-severe plaque psoriasis. There is a clear need for national consensus statements due to the extended role and high availability of literature on these agents. As a result of an initiative of the Ministry of Health, a multidisciplinary expert panel of dermatologists and pharmacists with practical experience in the clinical management of psoriasis were invited to be part of a work group to update the previous practical guidelines on the biologic treatment of psoriasis published in the Journal of Dermatological Treatment, 2014. The overall aim of this consensus document is to deliver evidence-based recommendations on the use, screening, and monitoring of biologic therapy in patients with moderate-to-severe plaque psoriasis. These recommendations also address the use of biologic therapy in special patient populations. They were developed after rigorous evaluation of existing international guidelines as well as the latest emerging evidence. Updates of the present consensus document will be provided as needed to incorporate new data or agents.

Persistent expression of interleukin-17 and downstream effector cytokines in recalcitrant psoriatic lesions after ustekinumab treatment

The interleukin (IL)-23/T-helper (Th)17 axis is considered central to the pathogenesis of psoriasis, with IL-36γ considered a marker for histological differential diagnosis. However, expression data regarding key cytokines in the pathogenesis of psoriasis, as well as data on the effects of IL-23 inhibition on downstream cytokines in human psoriatic skin, are limited. We investigated the expression profile of key cytokines and the effect of ustekinumab (UST) on cytokine expression in human psoriatic tissue. Tumor necrosis factor (TNF)-α, IL-23, IL-17A, and IL-22 were highly expressed in the epidermis, dermal papillae, and upper dermis in patients with psoriasis compared with controls; IL-36γ was strongly expressed in the upper epidermis. Compared with the untreated group, expression intensity and area of IL-23 were significantly decreased in the UST group; expression areas of TNF-α, IL-17A, IL-22, and IL-36γ did not differ. This study identified the distribution and quantitative expression levels of key cytokines in psoriatic lesions and demonstrated that only IL-23 was downregulated without blocking downstream effector cytokines in recalcitrant psoriatic lesions during UST treatment. Our results suggest that, although IL-23 is inhibited, the persistent expression of IL-17 through an alternative pathway maintains the vicious cycle of the TNF-α/IL-23/IL-17 axis with IL-36γ, inducing refractory psoriatic lesions in patients with well-controlled psoriasis.

Microglia-Derived Interleukin 23: A Crucial Cytokine in Alzheimer's Disease?

Neuronal cell death, amyloid β plaque formation and development of neurofibrillary tangles are among the characteristics of Alzheimer's disease (AD). In addition to neurodegeneration, inflammatory processes such as activation of microglia and astrocytes are crucial in the pathogenesis and progression of AD. Cytokines are essential immune mediators of the immune response in AD. Recent data suggest a role of interleukin 23 (IL-23) and its p40 subunit in the pathogenesis of AD and corresponding animal models, in particular concerning microglia activation and amyloid β plaque formation. Moreover, in animal models, the injection of anti-p40 antibodies resulted in reduced amyloid β plaque formation and improved cognitive performance. Here, we discuss the pathomechanism of IL-23 mediated inflammation and its role in AD.

Microneedle-mediated transdermal drug delivery for treating diverse skin diseases

Transdermal drug delivery is an attractive route for dermatological disease therapy because it can directly target the lesion site on the skin, reduce adverse reactions associated with systemic administration, and improve patient compliance. However, the stratum corneum, as the main skin barrier, severely limits transdermal drug penetration, with compromised bioavailability. Microneedles (MNs), which are leveraged to markedly improve the penetration of therapeutic agents by piercing the stratum corneum and creating hundreds of reversible microchannels in a minimally invasive manner, have been envisioned as a milestone for effective transdermal drug delivery, especially for superficial disease therapy. Here, the emergence of versatile MNs for the transdermal delivery of various drugs is reviewed, particularly focusing on the application of MNs for the treatment of diverse skin diseases, including superficial tumors, scars, psoriasis, herpes, acne, and alopecia. Additionally, the promises and challenges of the widespread translation of MN-mediated transdermal drug delivery in the dermatology field are summarized.

IL-33/Vitamin D Crosstalk in Psoriasis-Associated Osteoporosis

Patients with psoriasis (Pso) and, in particular, psoriatic arthritis (PsoA) have an increased risk of developing osteoporosis (OP). It has been shown that OP is among the more common pathologies associated with Pso, mainly due to the well-known osteopenizing conditions coexisting in these patients. Pso and OP share common risk factors, such as vitamin D deficiency and chronic inflammation. Interestingly, the interleukin (IL)-33/ST2 axis, together with vitamin D, is closely related to both Pso and OP. Vitamin D and the IL-33/ST2 signaling pathways are closely involved in bone remodeling, as well as in skin barrier pathophysiology. The production of anti-osteoclastogenic cytokines, e.g., IL-4 and IL-10, is promoted by IL-33 and vitamin D, which are stimulators of both regulatory and Th2 cells. IL-33, together with other Th2 cytokines, shifts osteoclast precursor differentiation towards macrophage and dendritic cells and inhibits receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis by regulating the expression of anti-osteoclastic genes. However, while the vitamin D protective functions in OP and Pso have been definitively ascertained, the overall effect of IL-33 on bone and skin homeostasis, because of its pleiotropic action, is still controversial. Emerging evidence suggests a functional link between vitamin D and the IL-33/ST2 axis, which acts through hormonal influences and immune-mediated effects, as well as cellular and metabolic functions. Based on the actions of vitamin D and IL-33 in Pso and OP, here, we hypothesize the role of their crosstalk in the pathogenesis of both these pathologies.

Imiquimod-induced skin inflammation is relieved by knockdown of sodium channel Nax

Na_x is an atypical sodium channel that mediates inflammatory pathways in pathological conditions of the skin. In this study, we developed a skin inflammation model in the rabbit ear through application of imiquimod (IMQ). Knockdown of Na_x using RNAi attenuated IMQ-induced skin inflammation, including skin erythema, scaling and papule formation. Histologic analysis showed that thickening and insufficient differentiation of the epidermis found in psoriasis-like skin were normalized by administration of Na_x -RNAi. Excessive infiltration of inflammatory cells found in inflammatory lesions, such as mast cells, eosinophils, neutrophils, T cells and macrophages, was reduced by Na_x -RNAi. Expression of S100A9, which is a downstream gene of Na_x and a mediator of inflammation, was decreased by Na_x -RNAi. Our results demonstrated that knockdown of Na_x ameliorated IMQ-induced psoriasis-like skin inflammation in vivo. Thus, targeting of Na_x may represent a potential therapeutic option for the treatment of psoriasis.

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.

Metformin inhibits IL-1β secretion via impairment of NLRP3 inflammasome in keratinocytes: implications for preventing the development of psoriasis

Psoriasis is a systemic inflammatory disease significantly associated with comorbidities including type 2 diabetes mellitus (T2DM). Metformin is utilized as a first-line agent for treating T2DM. Although metformin reportedly inhibits mature IL-1β secretion via NLRP3 inflammasome in macrophages of T2DM patients, it remains unclear whether it affects skin inflammation in psoriasis. To test this, we analysed normal human epidermal keratinocytes (NHEKs), a major skin component, stimulated with the key mediators of psoriasis development, TNF-α and IL-17A. This stimulation induced the upregulation of pro-IL-1β mRNA and protein levels, and subsequently mature IL-1β secretion, which was inhibited by metformin treatment. To further reveal the mechanism involved, we examined how metformin treatment affected NLRP3 inflammasome activated by TNF-α and IL-17A stimulation. We found that this treatment downregulated caspase-1 expression, a key mediator of NLRP3 inflammasome. Furthermore, inhibitors of AMPK and SIRT1 abrogated the downregulation of caspase-1 induced by metformin treatment, indicating that AMPK and SIRT1 are essential for the inhibitory effect on NLRP3 inflammasome in NHEKs. As IL-1β stimulation induced upregulation of IL-36γ, CXCL1, CXCL2, CCL20, S100A7, S100A8 and S100A9 mRNA and protein levels in NHEKs, we examined whether metformin treatment affects such gene expression. Metformin treatment inhibited upregulation of IL-36γ, CXCL1, CXCL2, CCL20, S100A7, S100A8 and S100A9 mRNA and protein levels induced by TNF-α and IL-17A stimulation. Finally, we examined whether metformin administration affected psoriasis development in an imiquimod-induced mouse psoriasis model. Oral metformin treatment significantly decreased ear thickness, epidermal hyperplasia and inflammatory cell infiltration. A cytokine profile in the epidermis under metformin treatment showed that IL-1β, Cxcl1, Cxcl2, S100a7, S100a8 and S100A9 mRNA levels were downregulated compared with control levels. These results indicate that metformin administration prevented psoriasis development in vivo. Collectively, our findings suggest that metformin-mediated anti-psoriatic effects on the skin have the potential for treating psoriasis in T2DM patients.

CNS-Specific Synthesis of Interleukin 23 Induces a Progressive Cerebellar Ataxia and the Accumulation of Both T and B Cells in the Brain: Characterization of a Novel Transgenic Mouse Model

Interleukin 23 (IL-23) is a key mediator in neuroinflammation in numerous autoimmune diseases including multiple sclerosis (MS). However, the pathophysiology of IL-23 and how it contributes to neuroinflammation is poorly defined. To further clarify the role of IL-23 in CNS inflammation, we generated a transgenic mouse model (GF-IL23) with astrocyte-targeted expression of both IL-23 subunits, IL-23p19, and IL-23p40. These GF-IL23 mice spontaneously develop a progressive ataxic phenotype, which corresponds to cerebellar tissue destruction, and inflammatory infiltrates most prominent in the subarachnoidal and perivascular space. The CNS-cytokine milieu was characterized by numerous inflammatory mediators such as IL-17a and IFNγ. However, the leukocytic infiltrates were surprisingly predominated by B cells. To further examine the impact of the CNS-specific IL-23 synthesis on an additional systemic inflammatory stimulus, we applied the LPS-induced endotoxemia model. Administration of LPS in GF-IL23 mice resulted in early and pronounced microglial activation, enhanced cytokine production and, in sharp contrast to control animals, in the formation of lymphocytic infiltrates. Our model confirms a critical role for IL-23 in the induction of inflammation in the CNS, in particular facilitating the accumulation of lymphocytes in and around the brain. Thereby, CNS-specific synthesis of IL-23 is able to induce a cascade of inflammatory cytokines leading to microglia activation, astrocytosis, and ultimately tissue damage. The presented transgenic model will be a useful tool to further dissect the role of IL-23 in neuroinflammation.

Clinical and molecular evaluation of therapy with the use of cyclosporine A in patients with psoriasis vulgaris

BACKGROUND

Psoriasis course involves increased secretion of pro-inflammatory cytokines, among others, a beta transforming growth factor (TGFβs) and its receptors. Cyclosporine A (CsA), an immunosuppressive medicine with the molecular mechanism of operation connected with the properties of cell cycle suppression, is often used in the treatment of severe forms of psoriasis. The efficacy of therapy is assessed based on the disease clinical progression indexes - Psoriasis Area and Severity Index (PASI), body surface area (BSA), and Dermatology Life Quality Index (DLQI). The aim of the study was the evaluation of the efficacy of the CsA treatment of patients with psoriasis vulgaris, based on the clinical parameters and an assessment of the expression profiles of TGFβs and TGFβRs, depending on the concurrent diabetes and metabolic syndrome.

METHODS

The group under study composed of 32 patients (15 with the metabolic syndrome, seven with diabetes) treated with CsA for 84 days. The molecular analysis included extraction of RNA, assessment of TGβF1-3, TGFβRI-III gene expression with the use of the RTqPCR method. The clinical assessment of the effects of this pharmacotherapy involved evaluation of the parameters: PASI, BSA, DLQI before therapy commencement, on the 42nd and 84th days of therapy.

RESULTS

A statistically significant change in the transcription activity of TGFβ1 in patients with and without diabetes (P = 0.018) and patients with and without metabolic syndrome (P = 0.023) was shown that on the 84th day of therapy.

CONCLUSIONS

TGFb1 may be claimed as the supplementary molecular marker to evaluate the efficacy of CsA therapy. It seems that systemic diseases have an effect on the efficacy of the applied pharmacotherapy and the course of psoriasis.

Differential efficacy of biologic treatments targeting the TNF-α/IL-23/IL-17 axis in psoriasis and psoriatic arthritis

Psoriasis and psoriatic arthritis cause significant physical and psychological burdens for afflicted individuals. An accelerated TNF-α/IL-23/IL-17 axis is their major pathomechanism; therefore, anti-TNF-α/IL-23/IL-17 biologics are very effective for the treatment of skin and joint lesions in psoriasis and psoriatic arthritis. Given that the IL-17 signature is more upregulated in the skin than in synovium in psoriatic arthritis, anti-IL-23/IL-17 agents seem to be superior to anti-TNF-α remedies in the treatment of skin lesions. In this review, we focus on the differential efficacy of anti-TNF-α/IL-23/IL-17 biologics in psoriasis and psoriatic arthritis.

Variances in the mRNA expression profile of TGF-β1-3 isoforms and its TGF-βRI-III receptors during cyclosporin a treatment of psoriatic patients

Introduction

Psoriasis is a chronic, immunologic, multi-factor inflammatory skin disease, strongly associated with a higher level of a number of cytokines, such as isoforms of transforming growth factor β (TGF-β1–3) and its receptors (TGF-βRI–III). One of the most popular and important drugs used to treat this disease is cyclosporin A (CsA).

Aim

The aim of this study was to investigate the expression of genes encoding the transforming growth factor (TGF)-β isoforms and receptors of the cytokine TGF-βRs in psoriatic patients during an 84-day long observation of the effects of cyclosporin A therapy. It made an attempt to determine the usefulness of testing mRNA expression of TGF-β1–3 and its receptors TGF-βRI–III as the supplementary molecular markers of lost sensitivity to the medicine.

Material and methods

The study group consisted of 32 patients with psoriasis (20 men and 12 women) treated with cyclosporin A. The changes in expression patterns of TGF-β1-3 and TGF-βRI-III were performed by real-time quantitative reverse transcription PCR (RTqPCR).

Results

The expression of TGF-β1-3 and TGF-βRI-III were detected in the whole period of therapy with CsA. Changes in transcriptional activities of TGF-β1–3 and TGF-βRI–III during pharmacotherapy were observed. Differences in the expression of these genes were found before and after 42 and 84 days of using CsA.

Conclusions

The changes in expression profiles of TGF-β1-3 and TGF-βRI-III during CsA therapy can be a useful molecular marker of lost sensitivity to the medicine.

Association between psoriasis and vitamin D: Duration of disease correlates with decreased vitamin D serum levels: An observational case-control study

Recent literature has focused on the association of psoriasis with lower than normal or highly deficient vitamin D blood levels.To investigate the controversial association between psoriasis and vitamin D levels.From 2012 to 2014, 561 subjects were assessed, of which 170 had psoriasis, 51 had an autoimmune bullous, and 340 were healthy patients. Anagraphical data, 25(OH)D blood levels, and seasons of vitamin D levels assessments were recorded for each group.Vitamin D levels were significantly different among the 3 groups (K = 151.284; P = .0001). Psoriatic patients had significantly lower serum levels of 25(OH)D (21.8 ng/mL) than healthy controls (34.3 ng/mL) (chi-square = 11.5; P = .0007). Patients with bullous diseases showed the lowest vitamin D mean values (18.2 ng/mL). The linear multiple regression model showed 25(OH)D levels to be influenced by age, season of blood vitamin D levels assessment, and psoriasis duration.These results confirm the reduced vitamin D levels in psoriatic patients when compared to healthy controls, and provide new evidence regarding the association of vitamin D levels and psoriasis duration. The limits of our study include its observational nature and the small number of patients undergoing biological immunosuppressive therapies.

Autoimmunity and autoimmune co-morbidities in psoriasis

Psoriasis is characterized by widespread scaly erythematous plaques that cause significant physical and psychological burdens for the affected individuals. Accelerated inflammation driven by the tumour necrosis factor-α/interleukin-23/interleukin-17 axis is now known to be the major mechanism in the development of psoriasis. In addition, psoriasis has an autoimmune nature that manifests as autoreactive T cells and is co-morbid with other autoimmune diseases, such as autoimmune bullous diseases, vitiligo, alopecia and thyroiditis. In this article, we review the recent topics on autoimmunity and autoimmune co-morbidities in psoriasis.

Atopic dermatitis: immune deviation, barrier dysfunction, IgE autoreactivity and new therapies

Atopic dermatitis (AD) is a chronic or chronically relapsing, eczematous, severely pruritic skin disorder mostly associated with IgE elevation and skin barrier dysfunction due to decreased filaggrin expression. The lesional skin of AD exhibits Th2- and Th22-deviated immune reactions that are progressive during disease chronicity. Th2 and Th22 cytokines further deteriorate the skin barrier by inhibiting filaggrin expression. Some IgEs are reactive to self-antigens. The IgE autoreactivity may precipitate the chronicity of AD. Upon activation of the ORAI1 calcium channel, atopic epidermis releases large amounts of thymic stromal lymphopoietin (TSLP), which initiates the Th2 and Th22 immune response. Th2-derived interleukin-31 and TSLP induce an itch sensation. Taken together, TSLP/Th2/Th22 pathway is a promising target for developing new therapeutics for AD. Enhancing filaggrin expression using ligands for the aryl hydrocarbon receptor may also be an adjunctive measure to restore the disrupted barrier function specifically for AD.

"Inflammatory skin march" in atopic dermatitis and psoriasis

BACKGROUND

Comorbidities of cardiovascular diseases (CVDs), metabolic syndrome and autoimmune diseases with systemic inflammation are recent topics in medicine. Inflammatory skin diseases such as atopic dermatitis and psoriasis are an active source of diverse proinflammatory cytokines and chemokines, which are readily detectable in the circulation and are likely to be involved in developing comorbidities.

EVIDENCE

Both atopic dermatitis and psoriasis are frequently comorbid with CVD, metabolic syndrome and autoimmune diseases, the consequence of which is called "inflammatory skin march", "psoriatic march" or "march of psoriasis".

CONCLUSION

In this review, we summarize the epidemiological evidence and pathogenetic concepts regarding inflammatory skin march in atopic dermatitis and psoriasis.

Local effects of adipose tissue in psoriasis and psoriatic arthritis

The structure and physiological state of the local white adipose tissue (WAT) located underneath the lesional psoriatic skin and inside of the joints affected by psoriatic arthritis play an important role in the pathophysiology of these diseases. WAT pads associated with inflammatory sites in psoriasis and psoriatic arthritis are, correspondingly, dermal WAT and articular adipose tissue; these pads demonstrate inflammatory phenotypes in both diseases. Such local WAT inflammation could be the primary effect in the pathophysiology of psoriasis leading to the modification of the local expression of adipokines, a change in the structure of the basement membrane and the release of keratinocytes with consequent epidermal hyperproliferation during psoriasis. Similar articular adipose tissue inflammation can lead to the induction of structural modifications and synovial inflammation in the joints of patients with psoriatic arthritis.

Cardiovascular and Metabolic Diseases Comorbid with Psoriasis: Beyond the Skin

A close association of systemic inflammation with cardiovascular diseases and metabolic syndrome is recently a popular topic in medicine. Psoriasis is a chronic inflammatory skin disease with a prevalence of approximately 0.1-0.5% in Asians. It is characterized by widespread scaly erythematous macules that cause significant physical and psychological burdens for the affected individuals. The accelerated inflammation driven by the TNF-α/IL-23/IL-17A axis is now known to be the major mechanism in the development of psoriasis. Psoriasis is not a mere skin disease; it is significantly associated with cardiovascular diseases and metabolic syndrome, which suggests that the chronic skin inflammation extends the systemic inflammation beyond the skin. In this article, we review the epidemiological and pathological aspects of psoriasis and its comorbidities.