Tissue and Serum Inflammatory Cytokine Levels in Korean Psoriasis Patients: A Comparison between Plaque and Guttate Psoriasis

Cytokines in psoriasis: From pathogenesis to targeted therapy

Psoriasis is a multifactorial disease that affects 0.84% of the global population and it can be associated with disabling comorbidities. As patients present with thick scaly lesions, psoriasis was long believed to be a disorder of keratinocytes. Psoriasis is now understood to be the outcome of the interaction between immunological and environmental factors in individuals with genetic predisposition. While it was initially thought to be solely mediated by cytokines of type-1 immunity, namely interferon-γ, interleukin-2, and interleukin-12 because it responds very well to cyclosporine, a reversible IL-2 inhibitor; the discovery of Th-17 cells advanced the understanding of the disease and helped the development of biological therapy. This article aims to provide a comprehensive review of the role of cytokines in psoriasis, highlighting areas of controversy and identifying the connection between cytokine imbalance and disease manifestations. It also presents the approved targeted treatments for psoriasis and those currently under investigation.

Advances and Controversies in Our Understanding of Guttate and Plaque Psoriasis

Acute guttate psoriasis (AGP) is considered an uncommon variant of psoriasis (PsO), characterized as a widespread eruption of erythematous, psoriasiform papules, and plaques on the trunk, extremities, and scalp. Predisposing factors include a family history of PsO, variation in the main PsO susceptibility gene HLA-Cw*0602, and previous infection with viruses or acute β-hemolytic Streptococcus A program focused on controversies and recent advances in understanding AGP was presented at the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) 2022 annual meeting. Topics included an overview of clinical presentation and natural history, predisposing genetic and environmental factors, and the recent molecular profiling that supports classification of AGP as a form of PsO. Early molecular profiling studies using proteomic signatures have suggested similarities between AGP and contact dermatitis, but recent studies using gene expression profiling and gene set enrichment scores demonstrate that AGP is more similar to chronic PsO. The expression of regulatory immune pathways seen with AGP suggests potential for early and sustained remission if the disease is suppressed by targeted treatments. Published case reports documenting clinical improvement of AGP with biologics that antagonize interleukin (IL)-12/23, IL-23, and IL-17 support the role of the IL-23/IL-17 axis in AGP, similar to that in PsO. Data supporting the use of antibiotics and other therapeutic agents for AGP are lacking, and randomized controlled trials are needed. Trial design for AGP is challenged by the low incidence, tendency for spontaneous remission, lack of validated end points, and the need for long-term follow up.

Bioinformatic Analysis of the Potential Common Pathogenic Mechanisms for Psoriasis and Metabolic Syndrome

The pathogeneses of psoriasis and metabolic syndrome are closely related; however, the underlying biological mechanisms are yet to be clarified. A psoriasis training set was downloaded from the Gene Expression Omnibus database and analyzed to identify the differentially expressed genes (|logFC|> 1 and adjust P < 0.05). Differentially expressed genes for metabolic syndrome were obtained from the GeneCards, Online Mendelian Inheritance in Man, and DisGeNET databases, and crosstalk genes were obtained for multiple enrichment analysis after identifying the disease intersection. Characteristic crosstalk genes were screened using the least absolute shrinkage and selection operator regression model and random forest tree model, and the genes with area under the receiver operating characteristic curve > 0.7 were selected for validation by the two validation sets. Differential analyses of immune cell infiltration were performed on psoriasis lesion and control samples using the CIBERSORT and ImmuCellAI methods, and correlation analyses were performed between the screened signature crosstalk genes and immune cell infiltration. Significant crosstalk genes were analyzed based on the psoriasis area and severity index and on the responses to biological agents. We found five signature genes (NLRX1, KYNU, ABCC1, BTC, and SERPINB4) were screened based on two machine learning algorithms, and NLRX1 was validated. The infiltration of multiple immune cells in psoriatic lesions and non-lesions was associated with NLRX1 expression. NLRX1 was found to be associated with psoriasis severity and response rate after the use of biologics. NLRX1 could be a significant crosstalk gene for psoriasis and metabolic syndrome.

Evaluation of Serum Proinflammatory Cytokine IL-17A and Tight Junction Protein Claudin-1 in Psoriasis

Objective

This study aimed to estimate serum IL-17A and Claudin-1 levels, investigate their correlation, and evaluate their diagnostic significance as potential blood-based biomarkers in psoriasis.

Methods

Serum IL-17A and Claudin-1 concentrations were determined using enzyme-linked immunosorbent assay (ELISA). Statistical analyses were performed to determine differences in serum levels of IL-17A and Claudin-1, their bivariable correlation with psoriasis severity, as Psoriasis Area Severity Index (PASI), and their predictive abilities using receiver operating characteristic (ROC) curves.

Results

Significantly higher IL-17A and lower Claudin-1 levels were found in psoriasis (p < 0.05). PASI did not correlate significantly with either IL-17A or Claudin-1 in psoriasis and their subtypes. The only significant correlation between serum IL-17A and Claudin-1 was shown in late-onset psoriasis (r = 0.630, p = 0.028). ROC curve analysis indicated the serum IL-17A, serum Claudin-1, and combination of IL-17A and serum Claudin-1 for predicting psoriasis with the areas under the curve (AUC) of 0.951 (p < 0.0001), 0.709 (p = 0.0119), and 0.949 (p < 0.0001), respectively. Moreover, the potential role in distinguishing between early-onset and late-onset psoriasis: we obtained serum IL-17A, serum Claudin-1, and their combination AUC of 0.590 (p = 0.3126), 0.741 (p = 0.0045), and 0.741 (p = 0.0067), respectively. However, none of the serum IL-17A, serum Claudin-1, and their combination was well-performed discriminating mild psoriasis from moderate-to-severe psoriasis with AUC of 0.553 (p = 0.5596), 0.518 (p = 0.8539), and 0.559 (p = 0.5225), respectively.

Conclusion

These preliminary results suggest that the serum Claudin-1 as a potential biomarker and the relationship and possible regulatory interactions between IL-17A and Claudin-1 in psoriasis are distinguishable by age of onset.

Cytokine Profiles and the Relationship of Disease Severity in Patients with Psoriasis

Background

Psoriasis is a chronic skin disease characterized by hyperproliferation of keratinocytes and increased inflammation. Previous studies have detected the levels of cytokines in the serum of patients with psoriasis, yet few multi-cytokine combination studies have been reported.

Objective

The aim of the study was to compare the levels of cytokines in the serum between patients with psoriasis and healthy controls, elucidate which factors influence the psoriasis progression.

Methods

A total of 39 psoriasis patients and 30 healthy volunteers were enrolled. The venous blood was collected and the levels of 13 inflammatory cytokines were measured by human inflammation panel 1 kit. The severity of the disease was determined according to the psoriasis area and severity index (PASI) score.

Results

Compared with healthy controls, the levels of nine cytokines (IFN-γ, TNF-α, IL-1β, IL-6, IL-10, IL-12P40, IL-18, IL-17A and IL-23) were significantly increased, while the level of MCP-1 decreased in psoriatic patients. In addition, except for MCP-1, IL-10 and IL-12P40, these cytokine levels were positively correlated with the PASI score. Furthermore, there were higher serum lever of IFN-γ, TNF-α, IL-1β, IL-6, IL-17A, IL-18 and IL-23 in active psoriasis than healthy controls and retrograde psoriasis.

Conclusions

Increased serum levels of IFN-γ, TNF-α, IL-1β, IL-6, IL-17A, IL-18 and IL-23 in psoriatic patients were associated with PASI and the stage of disease, which suggested that these cytokines play an important role in the pathogenesis of psoriasis. The detection of these cytokines can better observe the disease activity of psoriasis and optimize the treatment strategy.

Comparison of Th1 and Th17 Inflammatory Cytokine Profiles Between Chronic Plaque and Acute Guttate Psoriasis

Background

The phenotypic heterogeneity of psoriasis is suspected to reflect differences in its pathogenesis, but not yet completely elucidated. Studies of the Th1 and Th17 cytokines associated with different phenotypes of psoriasis have yielded inconsistent results.

Objective

To investigate the tissue expression levels of Th1 and Th17 cytokines among patients with chronic plaque psoriasis, acute guttate psoriasis, and healthy control.

Methods

A total of 20 patients with psoriasis (10 with chronic plaque type and 10 with acute guttate type) and 5 healthy controls were enrolled. The tissue mRNA and protein levels of following cytokines were measured: interleukin (IL)-12, IL-2, interferon (IFN)-γ, IL-23, IL-17A, and IL-22.

Results

The tissue mRNA levels of IL-12, IFN-γ, IL-23, IL-17A, IL-22 and the protein levels of IL-12, IL-2, IFN-γ, IL-17A, IL-22 were significantly increased in the psoriasis patients compared with the healthy controls. In comparisons of the subtypes, the tissue mRNA level of IFN-γ was increased in acute guttate psoriasis, whereas the protein levels of IL-12 and IL-17A were significantly increased in chronic plaque psoriasis. The cytokine ratios of IL-17A/IL-2 and IL-22/IL-2 were significantly higher in chronic plaque psoriasis than in acute guttate psoriasis.

Conclusion

We confirmed that the tissue levels of Th1 and Th17 cytokines were increased in psoriasis patients compared with healthy controls. The increased IFN-γ mRNA level in acute guttate psoriasis and increased IL-12 and IL-17A protein levels in chronic plaque psoriasis suggest that an imbalance between Th1 and Th17 cytokines may play a role in the phenotypic transition of psoriasis.

Cytokine alterations in psoriasis: an updated review

INTRODUCTION

Psoriasis is a chronic immune-mediated disease affecting 125 million people globally. It is characterized by erythematous plaques in the skin, covered by silvery scales. However, non-cutaneous manifestations (e.g., joint symptoms in psoriatic arthritis) and a high prevalence of other immune-mediated diseases such as inflammatory bowel diseases reflect its systemic nature. So far, research on psoriasis pathogenesis has improved our knowledge of the roles of the immune system, and cytokines play significant roles in immune responses.

AREAS COVERED

Herein, we review cytokine changes in psoriasis patients. Moreover, we will investigate the possible relationships between disease severity and cytokines alongside describing cytokine alterations in psoriasis patients with other comorbidities. Lastly, we will discuss the biologics and their effects on cytokines in psoriasis patients.

EXPERT OPINION

Psoriasis could develop various clinical types and clinical manifestations in people. It is an immune-mediated disease, and these manifestations are associated with different impaired cytokines. Imbalanced cytokines could lead to abnormal keratinocytes, neovascularization, and inflammation in psoriasis patients. So, a better understanding of the cytokine roles can help one choose a specific cytokine-targeting biologic to treat psoriasis. Moreover, these cytokines may be used as a severity marker for following up with these patients.

IL-17 and its role in inflammatory, autoimmune, and oncological skin diseases: state of art

Recent data support the theory of the involvement of IL‐17 in the pathogenesis of several chronic inflammatory skin diseases (psoriasis, atopic dermatitis, acne, hidradenitis suppurativa) and autoimmune skin diseases (alopecia areata, vitiligo, bullous diseases). Even if the role of IL‐17 in inflammatory and autoimmune diseases has been reported extensively, its role in tumor is still controversial. Some reports show that Th17 cells eradicate tumors, while others reveal that they promote the initiation and early growth of tumors. Herein, we review the role of IL‐17 in the involvement of some common dermatologic diseases: psoriasis, atopic dermatitis, hidradenitis suppurativa, acne, vitiligo, melanoma, and nonmelanoma skin cancers.

Increased risk of atherosclerotic cardiovascular disease among patients with psoriasis in Korea: A 15-year nationwide population-based cohort study

The association between psoriasis and risk of atherosclerotic cardiovascular disease has not been thoroughly evaluated in a large longitudinal cohort of an Asian population. We conducted a nationwide population-based retrospective cohort study encompassing more than 1.7 million Koreans with a 15-year follow-up period. The period prevalence of psoriasis was 0.33% among the baseline participants (1997-2000). In Cox proportional hazard analyses, the individuals with psoriasis had a higher adjusted hazard ratio (HR) for incidence of overall atherosclerotic cardiovascular disease (HR, 1.18; 95% confidence interval [CI], 1.09-1.27) compared with controls. Subgroup analyses revealed that the risk for myocardial infarction was commonly increased in both sexes with moderate to severe psoriasis (male: HR, 2.09; 95% CI, 1.35-3.24; female: HR, 3.23; 95% CI, 1.34-7.76), whereas the risk for ischemic stroke was specifically increased in female individuals with moderate to severe psoriasis (HR, 2.02; 95% CI, 1.24-3.30). Our data suggest that appropriate medical screening for possible cardiovascular comorbidities is warranted in Asian psoriatic patients according to disease severity and sex.

Association of the TNF-α, IL-2, and IL-2RB gene variants with susceptibility to psoriasis in a Turkish cohort

Aim of the study

The aim of this study was to investigate the role TNF-α, IL-2, and IL-2RB variants in psoriasis (Ps) and to evaluate the association between these variants and clinical features.

Material and methods

A total of 74 psoriatic patients and 74 healthy individuals were genotyped for these variants by PCR and/or RFLP.

Results

The AA genotype of TNF-α (–308) was significantly more common in the patients (p = 0.013). TNF-α (–238) AA genotype was significantly increased in the patients (p = 0.028), while the GG genotype was decreased in the patient group, compared to the controls (p = 0.016). IL-2 (–330) variant GG and TT genotype was more common in the patients (p = 0.037, p = 0.009, respectively), while IL-2 (–330) GT genotype was increased in the control subjects (p = 0.001). IL-2 (–330) GG genotype frequency was significantly decreased (p = 0.021) and the TT genotype frequency was significantly increased among patients with psoriatic arthritis in comparison with Ps patients (p = 0.014). IL-2RB TC genotype frequency was significantly decreased and TT genotype frequency was significantly increased in the patients with positive family history of Ps compared to those who had a negative family history (p = 0.017, p = 0.014, respectively). Also, IL-2RB CC genotype was significantly increased among the patients with late-onset Ps in comparison with the early onset Ps group (p = 0.009). The frequency of IL-2 (–330) TT genotype was significantly higher in mild Ps patients than moderate-severe patients (p = 0.043).

Conclusions

Our data suggest a potential role of these genes as candidate genes for susceptibility to Ps in a Turkish cohort.

The potential role of Th17 lymphocytes in patients with psoriasis

BACKGROUND

Psoriasis is a chronic inflammatory disorder, characterized by increased keratinocyte proliferation due to abnormal differentiation of basal keratinocytes. The etiology of the disease is unclear, and according to the survey results, it is hypothesized that a combination of genetic and environmental factors prompts an abnormal immune response in patients with psoriasis. CD4+ Th cells play a multifaceted role in both immune defense and pathogenesis of certain diseases such as psoriasis. Nonetheless, the exact contribution of different subpopulations of Th cells in psoriasis is still not clear.

OBJECTIVE

The aim of present study was to determine the mRNA expression level of RORC as potential inducer of Th17 cell differentiation and expression pattern of Th17-signature cytokines (IL-17A and IL-22).

METHODS

Twenty patients with psoriasis and twenty-one healthy subjects were included in the study. Peripheral blood mononuclear cells (PBMCs) were separated and expression of three genes were determined by quantitative real-time reverse transcriptase PCR (qRT-PCR). Plasma levels of IL-17 and IL-22 were also evaluated by ELISA.

RESULTS

RORC, IL-17A and IL-22 gene expression was significantly higher in patients with psoriasis compared with healthy controls (P<0.05). In addition, a marked increase in plasma IL-17A and IL-22 levels was observed in patient group compared to controls (P<0.001).

STUDY LIMITATIONS

small number of patients.

CONCLUSION

These data suggest that Th17 response may contribute to the pathogenesis of psoriasis.

Serum levels of adipokines and cytokines in psoriasis patients: a systematic review and meta-analysis

Purpose

To evaluate the association of serum levels of adipokines and cytokines with psoriasis.

Materials and Methods

A comprehensive literature search was performed in PubMed, ScienceDirect and Web of Science for the available relevant studies published before December 1, 2016. Differences in serum marker levels between patients and controls were pooled as standardized mean differences (SMDs) with 95% confidence interval to combine the effect estimations. We also conducted stratified analysis, meta-regression analysis and sensitivity analysis.

Results

Sixty-three studies containing 2876 psoriasis patients and 2237 healthy controls were included in this meta-analysis. The pooled serum levels of TNF-α, IFN-γ, IL-2, IL-6, IL-8, IL-18, IL-22, chemerin, lipocalin-2, resistin, sE-selectin, fibrinogen and C3 were higher in psoriasis patients compared with healthy controls (all P < 0.05). In contrast, adiponectin levels were lower. Serum levels of IL-1β, IL-4, IL-10, IL-12, IL-17, IL-21, IL-23, visfatin and omentin were not significantly different between psoriasis patients and controls (all P > 0.05). However, increased serum levels of IL-17 correlated with psoriasis in men. For other biomarkers, age, gender and psoriasis area and severity index did not explain the differences in effect size between the studies.

Conclusions

Serum levels of TNF-α, IFN-γ, IL-2, IL-6, IL-8, IL-18, IL-22, chemerin, lipocalin-2, resistin, sE-selectin, fibrinogen, complement 3, and adiponectin correlate with psoriasis and can be used as potential biomarkers for psoriasis and response to the treatment. Future studies are needed to identify additional players involved in the pathogenesis of psoriasis and to fully decipher the underlying mechanism.

Effects of VitabridC12 on Skin Inflammation

Background

VitabridC¹² is newly developed and composed of vitamin C and Vitabrid (lamellar, hydrated zinc oxide).

Objective

In this study, we aimed to investigate the effects of VitabridC¹² on psoriasis and atopic dermatitis.

Methods

Mice with imiquimod-induced psoriasis or Dermatophagoides farinae-induced atopic dermatitis were applied with VitabridC¹². The effects of VitabridC¹² were evaluated by clinical features, histology, and immunologic features by examining cytokines and chemokines.

Results

In psoriasis model, VitabridC¹² decreased epidermal thickness and reduced inflammatory cell infiltration. In atopic dermatitis model, VitabridC¹² decreased dermal infiltration of inflammatory cells, epidermal hyperplasia, and hyperkeratosis. VitabridC¹² reduced the expression levels of proinflammatory mediators such as interleukin (IL)-1β, IL-6, IL-8, IL-17A, IL-22, tumor necrosis factor-α, CXCL1, CCL17, and CCL20 as well as COX-2 in imiquimod-induced psoriatic skin lesions. Likewise, VitabridC¹² reduced the expression levels of IL-4, IL-5, IL-13, thymic stromal lymphopoietin, and CCL4 in D. farinae-induced skin lesions, and decreased the serum immunoglobulin E level in the atopic dermatitis mouse model. Particularly, the VitabridC¹²-treated mice showed downregulated expressions of mitogen-activated protein kinase (MAPK), including extracellular signal-regulated kinase (ERK), p38, and MAPK/ERK kinase, as well as inhibited phosphorylation of nuclear factor-κB p65.

Conclusion

Taken together, these findings indicate that VitabridC¹² exhibits anti-inflammatory activities and is a promising candidate as a treatment option for psoriasis or atopic dermatitis.

Gene Expression Analysis of Inflammatory Cytokines in Korean Psoriatic Patients

Background

Although phenotypic heterogeneity of psoriasis is suggested by the alternate activation of either T-helper (Th)1-related or Th17-related cytokines, little is known about the mRNA levels of inflammatory cytokines.

Objective

To investigate whether there is differential expression of Th1-related and Th17-related inflammatory cytokine genes 1) between psoriatic patients and healthy controls, and 2) between patients with different psoriasis phenotypes.

Methods

Twenty-five patients with psoriasis (10 with guttate psoriasis and 15 with plaque psoriasis) and 5 healthy volunteers were enrolled in this study. The mRNA levels of circulating cytokines (interleukin [IL]-2, IL-12p40, interferon-γ, IL-17A, IL-22, and IL-23R) were measured by real-time reverse transcription polymerase chain reaction.

Results

The comparison between psoriatic and healthy control samples revealed that IL-12p40, IL-17A, and IL-22 mRNA levels were significantly higher (approximately 4∼6 folds) in the patients with psoriasis. The mRNA levels of these six cytokines in the blood did not differ between the guttate and plaque psoriasis groups.

Conclusion

We found that the mRNA levels of blood inflammatory cytokines (IL-12p40, IL-17A, and IL-22) were significantly elevated in patients with psoriasis compared to the levels in healthy controls, but they did not significantly differ between patients with guttate and plaque type psoriasis.

Quercetin ameliorates imiquimod-induced psoriasis-like skin inflammation in mice via the NF-κB pathway

Quercetin (QC) is a dietary flavonoid abundant in many natural plants. A series of studies have shown that it has been shown to exhibit several biological properties, including anti-inflammatory, anti-oxidant, cardio-protective, vasodilatory, liver-protective and anti-cancer activities. However, so far the possible therapeutic effect of QC on psoriasis has not been reported. The present study was undertaken to evaluate the potential beneficial effect of QC in psoriasis using a generated imiquimod (IMQ)-induced psoriasis-like mouse model, and to further elucidate its underlying mechanisms of action. Effects of QC on PASI scores, back temperature, histopathological changes, oxidative/anti-oxidative indexes, pro-inflammatory cytokines and NF-κB pathway in IMQ-induced mice were investigated. Our results showed that QC could significantly reduce the PASI scores, decrease the temperature of the psoriasis-like lesions, and ameliorate the deteriorating histopathology in IMQ-induced mice. Moreover, QC effectively attenuated levels of TNF-α, IL-6 and IL-17 in serum, increased activities of GSH, CAT and SOD, and decreased the accumulation of MDA in skin tissue induced by IMQ in mice. The mechanism may be associated with the down-regulation of NF-κB, IKKα, NIK and RelB expression and up-regulation of TRAF3, which were critically involved in the non-canonical NF-κB pathway. In conclusion, our present study demonstrated that QC had appreciable anti-psoriasis effects in IMQ-induced mice, and the underlying mechanism may involve the improvement of antioxidant and anti-inflammatory status and inhibition on the activation of the NF-κB signaling. Hence, QC, a naturally occurring flavone with potent anti-psoriatic effects, has the potential for further development as a candidate for psoriasis treatment.