Methotrexate restores the function of peripheral blood regulatory T cells in psoriasis vulgaris via the CD73/AMPK/mTOR pathway

Identification of an exosomal miRNA-mRNA regulatory network contributing to methotrexate efficacy

OBJECTIVE

Methotrexate (MTX) is an economic and effective medicine treatment for psoriasis. Extracellular vesicle (EV) miRNA biomarkers related to its efficiency have been identified in various diseases. Whether certain miRNA profiles are associated with psoriasis treatment is unknown. In order to determine specific miRNA biomarkers for MTX effectiveness prediction and the severity of psoriasis, our study looked at the variations in circulating EV miRNA profiles before and after MTX therapy.

METHODS

Plasma EV isolation and next-generation sequencing were performed to identify differentially expressed EV miRNAs between GRs (n = 14) and NRs (n = 6). Univariate and multiple linear regression analyses were performed to evaluate the correlation between PASI scores and miRNA expression levels.

RESULTS

15 miRNAs out of a total profile of 443 miRNAs were substantially different between GRs and NRs at baseline, 4 of them (miR-199a-5p, miR-195-5p, miR-196a-5p, and miR-1246) have the potential to distinguish between GRs and NRs [area under the curve (AUC) ≥ 0.70, all P < 0.05]. KEGG pathway analyses revealed differentially expressed miRNAs to potentially target immune-related pathways. SIRT1 was discovered to be a target of miR-199a-5p and involved in MAPK signaling pathway. MiR-191-5p and miR-21-5p expression levels have been discovered to positively correlate with PASI scores[P < 0.05].

CONCLUSION

This pilot investigation found that miR-199a-5p, miR-195-5p, miR-196a-5p, and miR-1246 might be prospective biomarkers to predict the efficacy of MTX, and that miR-191-5p and miR-21-5p were correlated with psoriasis severity. Five of them previously reported to be involved in MAPK signaling pathway, indicating a potential role of MTX in delaying the progression of psoriatic inflammation.

The Immunology of Psoriasis-Current Concepts in Pathogenesis

Psoriasis is one of the most common inflammatory skin diseases with a chronic, relapsing-remitting course. The last decades of intense research uncovered a pathological network of interactions between immune cells and other types of cells in the pathogenesis of psoriasis. Emerging evidence indicates that dendritic cells, TH17 cells, and keratinocytes constitute a pathogenic triad in psoriasis. Dendritic cells produce TNF-α and IL-23 to promote T cell differentiation toward TH17 cells that produce key psoriatic cytokines IL-17, IFN-γ, and IL-22. Their activity results in skin inflammation and activation and hyperproliferation of keratinocytes. In addition, other cells and signaling pathways are implicated in the pathogenesis of psoriasis, including TH9 cells, TH22 cells, CD8+ cytotoxic cells, neutrophils, γδ T cells, and cytokines and chemokines secreted by them. New insights from high-throughput analysis of lesional skin identified novel signaling pathways and cell populations involved in the pathogenesis. These studies not only expanded our knowledge about the mechanisms of immune response and the pathogenesis of psoriasis but also resulted in a revolution in the clinical management of patients with psoriasis. Thus, understanding the mechanisms of immune response in psoriatic inflammation is crucial for further studies, the development of novel therapeutic strategies, and the clinical management of psoriasis patients. The aim of the review was to comprehensively present the dysregulation of immune response in psoriasis with an emphasis on recent findings. Here, we described the role of immune cells, including T cells, B cells, dendritic cells, neutrophils, monocytes, mast cells, and innate lymphoid cells (ILCs), as well as non-immune cells, including keratinocytes, fibroblasts, endothelial cells, and platelets in the initiation, development, and progression of psoriasis.

AMPK activation modulates IL-36-induced inflammatory responses by regulating IκBζ expression in the skin

BACKGROUND AND PURPOSE

The interleukin (IL)-36 pathway is a critical player in the pathogenesis of pustular psoriasis. However, therapies targeting this pathway are limited or unaffordable (e.g. the anti-IL-36 receptor antibody). AMP-activated protein kinase (AMPK), a regulator of cellular energy and metabolism, is known to participate in inflammatory diseases. However, its role in IL-36-induced skin inflammation remains unclear. Therefore, we sought to investigate the role of AMPK signals in regulating IL-36-induced responses in the skin.

EXPERIMENTAL APPROACH

IL-36-stimulated primary normal human epidermal keratinocytes (NHEKs) and IL-36-injected (intradermally) BALB/c mice served as the cell and animal models, respectively. Additionally, 5-aminoimidazole-4-carboxamide riboside (AICAR) and A769662 served as AMPK activators.

KEY RESULTS

AICAR and A769662 significantly suppressed the IL-36-induced IL-8 (CXCL8) and CCL20 production from NHEKs. IL-36-induced IκBζ protein expression was prominently reduced and IKK/IκBα phosphorylation was attenuated by AICAR and A769662. Conversely, AMPKα knockdown increased IκBζ protein expression and IKK/IκBα phosphorylation in IL-36-treated NHEKs. Furthermore, AICAR and A769662 enhanced IL-36-induced-IκBζ protein degradation via the proteasome-dependent but not the lysosome-dependent pathway. Pretreatment of NHEKs with IL-36 slightly suppressed the AICAR- and A769662-triggered phosphorylation of AMPK and acetyl-CoA carboxylase. In the mouse model, topical application of AICAR significantly reduced ear swelling, redness, epidermal thickening, neutrophil infiltration and inflammatory and antimicrobial peptide gene expression.

CONCLUSION AND IMPLICATIONS

AMPK activation suppresses IL-36-induced IL-8 and CCL20 release by regulating IκBζ expression in keratinocytes and reduces IL-36-induced skin inflammation in mice, suggesting that AMPK activation is a potential strategy for treating patients with IL-36-mediated inflammatory skin disorders.

Caloric restriction for the immunometabolic control of human health

Nutrition affects all physiological processes occurring in our body, including those related to the function of the immune system; indeed, metabolism has been closely associated with the differentiation and activity of both innate and adaptive immune cells. While excessive energy intake and adiposity have been demonstrated to cause systemic inflammation, several clinical and experimental evidence show that calorie restriction (CR), not leading to malnutrition, is able to delay aging and exert potent anti-inflammatory effects in different pathological conditions. This review provides an overview of the ability of different CR-related nutritional strategies to control autoimmune, cardiovascular, and infectious diseases, as tested by preclinical studies and human clinical trials, with a specific focus on the immunological aspects of these interventions. In particular, we recapitulate the state of the art on the cellular and molecular mechanisms pertaining to immune cell metabolic rewiring, regulatory T cell expansion, and gut microbiota composition, which possibly underline the beneficial effects of CR. Although studies are still needed to fully evaluate the feasibility and efficacy of the nutritional intervention in clinical practice, the experimental observations discussed here suggest a relevant role of CR in lowering the inflammatory state in a plethora of different pathologies, thus representing a promising therapeutic strategy for the control of human health.

High-dimensional profiling of regulatory T cells in psoriasis reveals an impaired skin-trafficking property

BACKGROUND

Psoriasis is a chronic inflammatory skin disease with a Th17-skewed immune phenotype. Although it has been generally accepted that regulatory T cells (Tregs) in lesional psoriatic skin have functional impairment due to the local inflammatory microenvironment, the molecular properties of skin-homing psoriatic Tregs have not been well explored.

METHODS

We designed an extensive 39 marker mass cytometry (CyTOF) panel to deeply profile the immune landscape of skin-homing Tregs from 31 people with psoriasis stratified by psoriasis area severity index score as mild (n = 15) to moderate-severe (n = 16) and 32 healthy controls. We further validated the findings with an in-vitro chemokine-mediated Treg migration assay, immunofluorescent imaging of normal and psoriatic lesional skin and analysed public single-cell RNA-sequencing datasets to expand upon our findings into the local tissue microenvironments.

FINDINGS

We discovered an overall decrease in CLAhi Tregs and specifically, CLAhiCCR5+ Tregs in psoriasis. Functional markers CD39 and FoxP3 were elevated in psoriatic Tregs. However, CCR7 expression was significantly increased while CCR4 and CLA expression was reduced in psoriatic Tregs and CLAhi Tregs, which was associated with disease severity. Moreover, psoriatic Tregs revealed increased migratory capacity towards CCR7's ligands, CCL19/CCL21. Interrogation of public single-cell RNA sequencing data confirmed reduced expression of skin-trafficking markers in lesional-skin Tregs compared to non-lesioned skin, further substantiated by immunofluorescent staining.

INTERPRETATION

Psoriatic circulating Tregs showed an impaired skin-trafficking phenotype thus leading to insufficient suppression of ongoing inflammation in the lesional skin, expanding upon our current understanding of the impairment of Treg-mediated immunosuppression in psoriasis.

FUNDING

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Science and Information and Communications Technology (2020R1C1C1014513, 2021R1A4A5032185, 2020R1F1A1073692); and the new faculty research seed money grant of Yonsei University College of Medicine for 2021 (2021-32-0033).

Unlocking the role of the B7-H4 polymorphism in psoriasis: Insights into methotrexate treatment outcomes: A prospective cohort study

B7-H4 is a recently discovered member of B7 family that negatively regulates T-cell immunity, specifically Th1 and Th17 cell responses. However, its role in the pathogenesis of psoriasis has yet to be determined. This study aims to investigate the effect of B7-H4 polymorphism on the efficacy of methotrexate (MTX) and its mechanism in psoriasis. Four single nucleotide polymorphisms of B7-H4 were genotyped in 310 psoriatic patients who received 12-week MTX. The protein expression of B7-H4 in platelets was characterized using immunofluorescence staining, confocal laser scanning microscopy, and flow cytometry techniques. We found that GG genotype carriers of B7-H4 rs1935780 had a lower Psoriasis Area and Severity Index (PASI) 75 response rate and higher weight (p = 0.0245) and body mass index (p = 0.0185) than AA and AG genotype carriers. Multiple regression analysis showed that the PASI score at baseline (p = 0.01) and age at disease onset (p = 0.003) were positively correlated with PASI 75 response rate, while weight (p = 0.005) and the rs1935780 genotype (p = 0.003) were negatively associated with PASI 75 response rate. B7-H4 was expressed in the platelet plasma membrane and cytoplasm. Furthermore, the expression of B7-H4 protein in platelets was lower in good responders than in non-responders and was upregulated considerably after 12-week MTX or in vitro MTX stimulation in good responders. Collectively, these results demonstrate that psoriatic patients with GG genotype of B7-H4 rs1935780 had a poorer response to MTX. Low expression of B7-H4 protein in platelets correlated with better clinical outcomes of MTX in psoriasis.

The roles of T cells in psoriasis

Psoriasis is a recurring inflammatory skin condition characterized by scaly, red patches on the skin. It affects approximately 3% of the US population and is associated with histological changes such as epidermal hyperplasia, increased blood vessel proliferation, and infiltration of leukocytes into the skin's dermis. T cells, which are classified into various subtypes, have been found to play significant roles in immune-mediated diseases, particularly psoriasis. This paper provides a review of the different T lymphocyte subtypes and their functions in psoriasis, as well as an overview of targeted therapies for treating psoriasis.

MicroRNA-125a-5p regulates the effect of Tregs on Th1 and Th17 through targeting ETS-1/STAT3 in psoriasis

BACKGROUND

Psoriasis is an inflammatory disease mediated by helper T (Th)17 and Th1 cells. MicroRNA-125a (miR-125a) is reduced in the lesional skin of psoriatic patients. However, the mechanism by which miR-125a participates in psoriasis remains unclear.

METHODS

The levels of miR-125a-5p and its downstream targets (ETS-1, IFN-γ, and STAT3) were detected in CD4+ T cells of healthy controls and psoriatic patients by quantitative real-time PCR (qRT-PCR). In vitro, transfection of miR-125a-5p mimics was used to analyze the effect of miR-125a-5p on the differentiation of Th17 cells by flow cytometry. Imiquimod (IMQ)-induced mouse model was used to evaluate the role of upregulating miR-125a-5p by intradermal injection of agomir-125a-5p in vivo.

RESULTS

miR-125a-5p was downregulated in peripheral blood CD4+ T cells of psoriatic patients, which was positively associated with the proportion of regulatory T cells (Tregs) and negatively correlated with the Psoriasis Area and Severity Index (PASI) score. Moreover, the miR-125a-5p mimics promoted the differentiation of Tregs and downregulated the messenger RNA (mRNA) levels of ETS-1, IFN-γ, and STAT3 in murine CD4+ T cells. Furthermore, agomir-125a-5p alleviated psoriasis-like inflammation in an IMQ-induced mouse model by downregulating the proportion of Th17 cells.

CONCLUSIONS

miR-125a-5p may have therapeutic potential in psoriasis by restoring the suppressive function of Tregs on Th17 cells through targeting STAT3, and on Th1 cells indirectly through targeting ETS-1 and IFN-γ.

The update of treatment strategies in pediatrics with generalized pustular psoriasis in China

Generalized pustular psoriasis (GPP) is a severe subtype of psoriasis, commonly combined with systemic inflammation. Gene mutations have been found to be associated with GPP and vary by ethnicity. Systemic treatments are usually required for the severity and potential complications of GPP. However, there is no common consensus in China, especially among pediatric patients, whose data are scarce. Acitretin, methotrexate, and cyclosporine are widely used in pediatrics with GPP, while the adverse effects should be highlighted. The emergence of different biological agents brings us into a new era. This article discusses the genetic background of Chinese patients and demonstrates the evidence of treatment in pediatrics with GPP.

Resveratrol Ameliorates Imiquimod-Induced Psoriasis-Like Mouse Model via Reducing Macrophage Infiltration and Inhibiting Glycolysis

Purpose

Resveratrol (Res) is a natural polyphenol with anti-inflammatory and immunomodulatory effects. Alterations in metabolic pathways have been studied in psoriasis. This study is aimed to further explore the potential molecular mechanism of psoriasis improvement by Res.

Patients and Methods

Imiquimod (IMQ)-induced psoriasis-like mouse model was established to observe the effects of Res. NanoString nCounter Metabolic Pathways Panel was used to analyze the changed mRNA and qRT-PCR was used for validation. Flow cytometry was used to analyze immune cell subsets in skin lesions. In vitro, we observed the effects of Res on R848-stimulated macrophages glycolysis and inflammation.

Results

Res reduced the proliferation of keratinocytes and the secretion of inflammatory cytokines in IMQ-induced psoriasis-like mouse model. Psoriasis model skin lesions were in a state of hypoxia, with upregulated glycolysis and downregulated AMPK activity. Res inhibited the levels of hypoxia-related genes (hif1α, hif3α) and glycolysis-related genes (hk1, ldha), meanwhile increased the levels of AMPK genes (prkaa1, prkaa2). Flow cytometry analysis revealed that Res decreased the infiltration of macrophages in psoriasis-like lesions. In addition, Res decreased the secretion of macrophage-associated pro-inflammatory cytokines (IL-23, TNF-α, IL-1β). In vitro, Res diminished the secretion of IL-23, TNF-α, IL-1β, and lactate by R848-stimulated macrophages and activated AMPK.

Conclusion

This study suggested that Res diminished psoriasis symptoms by inhibiting macrophages infiltration and inhibiting glycolysis, which providing novel insights into the underlying mechanisms of therapeutic action of Res in the treatment of psoriasis.

Extracts from Seseli mairei Wolff attenuate imiquimod-induced psoriasis-like inflammation by inhibiting Th17 cells

Objective

Seseli mairei Wolff extracts (SMWE) are widely used to treat psoriasis as a Chinese medicine, but their effect and mechanism are unclear. This study verified the effect of SMWE on psoriasis by regulating Th17 cells.

Methods

HaCaT cells were treated with IL-17A in vitro to evaluate the effect of SMWE on psoriasis. In vivo, the mice psoriasis model was established using imiquimod (IMQ, 62.5 mg/d), and intragastrically treated with the different drugs for six days. The severity of skin inflammation was evaluated with Psoriasis Area and Severity Index (PASI) scores and pathology. The levels of inflammation cytokines were assessed with immunofluorescence, immunochemistry, ELISA, and real-time PCR. The number of Th17 cells was determined with flows.

Results

SMWE inhibited the proliferation of HaCaT cells and reduced the IL-17A-induced IL-6 production in vitro. In vivo, SMWE deduced the levels of IL-1β, IL-6, IL-8, IL-17A, IL-17F, IL-22, IL-23, and TNF-α, while increasing the level of IL-10 compared to the model group. SMWE also inhibited the levels of NF-κB, JAK2, and STAT3 proteins, while declining the expressions of Gr-1, and MPO. Interestingly, SMWE significantly decreased the number of Th17 cells.

Conclusion

SMWE inhibited the proliferation of HaCaT cells and attenuated the development of psoriasis lesions by inhibiting Th17 cells to regulate the levels of inflammation cytokines.

The PI3K-Akt-mTOR and Associated Signaling Pathways as Molecular Drivers of Immune-Mediated Inflammatory Skin Diseases: Update on Therapeutic Strategy Using Natural and Synthetic Compounds

The dysregulated phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway has been implicated in various immune-mediated inflammatory and hyperproliferative dermatoses such as acne, atopic dermatitis, alopecia, psoriasis, wounds, and vitiligo, and is associated with poor treatment outcomes. Improved comprehension of the consequences of the dysregulated PI3K/Akt/mTOR pathway in patients with inflammatory dermatoses has resulted in the development of novel therapeutic approaches. Nonetheless, more studies are necessary to validate the regulatory role of this pathway and to create more effective preventive and treatment methods for a wide range of inflammatory skin diseases. Several studies have revealed that certain natural products and synthetic compounds can obstruct the expression/activity of PI3K/Akt/mTOR, underscoring their potential in managing common and persistent skin inflammatory disorders. This review summarizes recent advances in understanding the role of the activated PI3K/Akt/mTOR pathway and associated components in immune-mediated inflammatory dermatoses and discusses the potential of bioactive natural products, synthetic scaffolds, and biologic agents in their prevention and treatment. However, further research is necessary to validate the regulatory role of this pathway and develop more effective therapies for inflammatory skin disorders.

Real-World Experience of Methotrexate in the Treatment of Skin Diseases: an Italian Delphi Consensus

BACKGROUND

After decades of use, methotrexate displays an established safety and efficacy profile in both in-hospital and outpatient settings. Despite its widespread use, there is surprisingly little clinical evidence to guide daily practice with methotrexate in dermatology.

OBJECTIVES

To provide guidance for clinicians in daily practice for areas in which there is limited guidance.

METHODS

A Delphi consensus exercise on 23 statements was carried out on the use of methotrexate in dermatological routine settings.

RESULTS

Consensus was reached on statements that cover six main areas: (1) pre-screening exams and monitoring of therapy; (2) dosing and administration in patients naïve to methotrexate; (3) optimal strategy for patients in remission; (4) use of folic acid; (5) safety; and (6) predictors of toxicity and efficacy. Specific recommendations are provided for all 23 statements.

CONCLUSIONS

In order to optimize methotrexate efficacy, it is essential to optimize treatment using appropriate dosages, carrying out a rapid drug-based step-up on a treat-to-target strategy and preferably using the subcutaneous formulation. To manage safety aspects appropriately, it is essential to evaluate patients' risk factors and carry out proper monitoring during the course of treatment.

Specific Activation of CB2R Ameliorates Psoriasis-Like Skin Lesions by Inhibiting Inflammation and Oxidative Stress

Psoriasis is a chronic inflammatory skin disease. Inflammation and oxidative stress play crucial roles in the pathogenesis of psoriasis. Cannabinoid receptor type 2 (CB2R) is an attractive target for treating various inflammatory disorders. However, the precise role and mechanism of CB2R activation in psoriasis remain to be further elucidated. In this study, imiquimod (IMQ)-induced experimental psoriasis mice and tumor necrosis factor-α (TNF-α)-activated keratinocytes (HaCaT) were used to examine the effect of CB2R activation on psoriasis-like lesions and the mechanism in vivo and in vitro. Our results demonstrated that activation of CB2R by the specific agonist GW842166X (GW) significantly ameliorated IMQ-induced psoriasiform skin lesions in mice by reducing epidermal thickness and decreasing plaque thickness. On the one hand, GW alleviated inflammation by decreasing inflammatory cytokines and abating inflammatory cell infiltration. On the other hand, this treatment reduced the level of iNOS and downregulated the expression of CB2R in psoriatic skin tissue. Further studies suggested that the Kelch-like ECH-associated protein 1/nuclear factor erythroid-2-related factor (Keap1/Nrf2) signaling pathway might be involved. Our findings reveal that selective activation of CB2R may serve as a new strategy for the treatment of psoriasis.

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.

AIM2 and Psoriasis

Psoriasis is a chronic inflammatory skin disease occurring worldwide, with multiple systemic complications, which seriously affect the quality of life and physical and mental health of patients. The pathogenesis of psoriasis is related to the environment, genetics, epigenetics, and dysregulation of immune cells such as T cells, dendritic cells (DCs), and nonimmune cells such as keratinocytes. Absent in melanoma 2 (AIM2), a susceptibility gene locus for psoriasis, has been strongly linked to the genetic and epigenetic aspects of psoriasis and increased in expression in psoriatic keratinocytes. AIM2 was found to be activated in an inflammasome-dependent way to release IL-1β and IL-18 to mediate inflammation, and to participate in immune regulation in psoriasis, or in an inflammasome-independent way by regulating the function of regulatory T(Treg) cells or programming cell death in keratinocytes as well as controlling the proliferative state of different cells. AIM2 may also play a role in the recurrence of psoriasis by trained immunity. In this review, we will elaborate on the characteristics of AIM2 and how AIM2 mediates the development of psoriasis.

Five Rutaceae family ethanol extracts alleviate H2O2 and LPS-induced inflammation via NF-κB and JAK-STAT3 pathway in HaCaT cells

This study was designed to investigate the effects of five Rutaceae family ethanol extracts (FRFEE): Citrus medica Linn (CML), Citrus aurantium L. Cv. Daidai (CAD), Citrus medica Linn. var. sarcodactylis (Noot.) Swingle (CMS),Citrus sinensis L. Osbeck (CSO) and Zanthoxylum bungeanum Maxim (ZBM) on retarding the progression of H₂O₂ and LPS-induced HaCaT cells. Cell inflammatory injury model was established by H₂O₂ and LPS. The alleviative effects of FRFEE were evaluated by detecting the activity of superoxide dismutase (SOD), glutathione (GSH) and the generation of reactive oxygen species (ROS). The inflammatory signaling pathways of NF-κB and JAK-STAT3 were detected by Western blotting, the mRNA expression levels of inflammatory factors and skin barrier factors were detected by RT-PCR. 50% ethanol extracts of five medicinal and food homologous herbs of Rutaceae family showed different levels of anti-oxidant and anti-inflammatory activities. The FRFEE effectively improved SOD and GSH content and decreased ROS levels. Meanwhile, FRFEE strongly suppressed two inflammatory signaling pathways NF-κB and JAK-STAT3. The RT-PCR examination of inflammatory factors and skin barrier factor revealed significant anti-inflammatory effects of FRFEE. It was worth noting that among the five extracts, Zanthoxylum bungeanum Maxim extract had the best anti-inflammatory and anti-oxidation effects. In addition, it could strongly inhibit the expression of psoriasis factor CCL20. In summary, these results suggested that Zanthoxylum bungeanum Maxim extract could be used as an anti-psoriatic agent in the treatment of psoriasis among FRFEE.

Regulatory T cells as metabolic sensors

Compelling experimental evidence links immunity and metabolism. In this perspective, we propose forkhead-box-P3 (FoxP3)⁺CD4⁺CD25⁺ regulatory T (Treg) cells as key metabolic sensors controlling the immunological state in response to their intrinsic capacity to perceive nutritional changes. Treg cell high anabolic state in vivo, residency in metabolically crucial districts, and recirculation between lymphoid and non-lymphoid sites enable them to recognize the metabolic cues and adapt their intracellular metabolism and anti-inflammatory function at the paracrine and systemic levels. As privileged regulators at the interface between neuroendocrine and immune systems, the role of Treg cells in maintaining metabolic homeostasis makes these cells promising targets of therapeutic strategies aimed at restoring organismal homeostasis not only in autoimmune but also metabolic disorders.

B7-H4 Polymorphism Influences the Prevalence of Diabetes Mellitus and Pro-Atherogenic Dyslipidemia in Patients with Psoriasis

Background: The co-inhibitory molecule B7-H4 is located in the genomic regions associated with type 1 diabetes (T1D) susceptibility. However, the correlation of B7-H4 with glycometabolism and dyslipidemia has never been studied. Objective: To explore the influence of B7-H4 polymorphism on the prevalence of diabetes mellitus (DM) and dyslipidemia in psoriasis. Methods: In this single-center cross-sectional study, we recruited 265 psoriatic patients receiving methotrexate (MTX) treatment. Thirteen single-nucleotide polymorphisms (SNPs) in B7-H4 were genotyped. Serum levels of total cholesterol (TC), triglycerides (TG), lipoprotein (a) (LP(a)), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein (LDL), apolipoprotein A1 (ApoA1), and apolipoprotein B (ApoB) were measured at baseline and week 12. Results: The GG genotype carriers of rs12025144 in B7-H4 had a higher prevalence of DM (57.14% vs. 17.71% vs. 18.67%, p = 0.0018), and had a poorer response to MTX in diabetic patients (p < 0.05), compared with AA or AG genotype carriers. The AG genotype of rs2066398 was associated with higher levels of pro-atherogenic lipids. MTX significantly downregulated the level of anti-atherogenic lipid ApoA1 in AA genotype carriers of rs2066398. Conclusions: The genotypes rs12025144 and rs2066398 in B7-H4 were correlated with a higher prevalence of DM and dyslipidemia in psoriasis, respectively.

A sharp decrease of Th17, CXCR3+-Th17, and Th17.1 in peripheral blood is associated with an early anti-IL-17-mediated clinical remission in psoriasis

Psoriasis-an immune-mediated skin disease-implicates in its pathophysiology by circulating pro-inflammatory cell populations, cytokines, and their interactions with the epidermis. The direct effect of approved anti-interleukin- (IL-)17A and anti-IL-17R biologic therapy on immunophenotyping of peripheral blood mononuclear lymphocytes' (PBMCs) relative sub-population frequencies in psoriasis patients has not yet been described. Using multiparameter flow cytometry we examined T-cell subpopulations characterized by CCR6, CCR4, and CXCR3 chemokine receptor surface expression at baseline and after initiation of biologic therapy in PBMCs collected from 30 psoriasis patients. Increased CD3+CD4+CXCR3+, CD3+CD4+CCR6+CCR4+CXCR3+(CXCR3+-Th17), and CD3+CD4+CCR6+CCR4-CXCR3+(Th17.1) cell populations were observed in patients with psoriasis in comparison to healthy individuals (n = 10). IL-17 therapeutic blockade decreased CD3+CD4+CCR6+, CD3+CD4+CXCR3+, CD3+CD4+CCR6-CXCR3+(Th1), CD3+CD4+CCR6+CCR4+(Th17), CD3+CD4+CCR6+CCR4+CXCR3+(CXCR3+-Th17), and CD3+CD4+CCR6+CCR4-CXCR3+(Th17.1) cell populations in responding psoriasis patients. Moreover, CD3+CD4-CCR6+, CD3+CD4-CXCR3+, CD3+CD4-CCR6+CCR4+(Tc17), and CD3+CD4-CCR6-CXCR3+(Tc1) percentages were also inhibited. Modulation of the same cell sub-populations was also assessed in patients treated with methotrexate (n = 4), apremilast (n = 4), and anti-IL-23 biologic treatment (n = 4). In our study, the levels and functional capacity of peripheral pro-inflammatory Th1, Th17, and additional CCR6+T cell sub-gated populations from psoriasis patients that were treated with anti-IL-17 or anti-IL-17R targeted biologic therapy were explored for the first time. Our data clearly demonstrate that early anti-IL-17 mediated clinical remission is accompanied by a significant decrease of Th1, Th17, CXCR3+-Th17, and Th17.1 cells.

Application and pharmacological mechanism of methotrexate in rheumatoid arthritis

Methotrexate (MTX) has been used for the treatment of rheumatoid arthritis (RA) for about forty years and to date MTX remains the part of global standard of treatment for RA. The efficacy of MTX in RA is the result of multiple mechanisms of action. In order to summarize the possible pharmacological mechanisms of MTX in the treatment of RA, this review will elaborate on folate antagonism, promotion of adenosine accumulation, regulation of inflammatory signaling pathways, bone protection and maintenance of immune system function.

IL-17 Pathway Members as Potential Biomarkers of Effective Systemic Treatment and Cardiovascular Disease in Patients with Moderate-to-Severe Psoriasis

Psoriasis is a chronic inflammatory condition associated with atherosclerotic cardiovascular disease (CVD). Systemic anti-psoriatic treatments mainly include methotrexate and biological therapies targeting TNF, IL-12/23 and IL-17A. We profiled plasma proteins from patients with moderate-to-severe psoriasis to explore potential biomarkers of effective systemic treatment and their relationship to CVD. We found that systemically well-treated patients (PASI < 3.0, n = 36) had lower circulating levels of IL-17 pathway proteins compared to untreated patients (PASI > 10, n = 23). Notably, IL-17C and PI3 were decreased with all four examined systemic treatment types. Furthermore, in patients without CVD, we observed strong correlations among IL-17C/PI3/PASI (r ≥ 0.82, p ≤ 1.5 × 10⁻¹²) pairs or between IL-17A/PASI (r = 0.72, p = 9.3 × 10⁻⁸). In patients with CVD, the IL-17A/PASI correlation was abolished (r = 0.2, p = 0.24) and the other correlations were decreased, e.g., IL-17C/PI3 (r = 0.61, p = 4.5 × 10⁻⁵). Patients with moderate-to-severe psoriasis and CVD had lower levels of IL-17A compared to those without CVD (normalized protein expression [NPX] 2.02 vs. 2.55, p = 0.013), and lower IL-17A levels (NPX < 2.3) were associated with higher incidence of CVD (OR = 24.5, p = 0.0028, 95% CI 2.1–1425.1). As a result, in patients with moderate-to-severe psoriasis, we propose circulating IL-17C and PI3 as potential biomarkers of effective systemic anti-psoriatic treatment, and IL-17A as potential marker of CVD.

Treatment Options and Goals for Patients with Generalized Pustular Psoriasis

Generalized pustular psoriasis (GPP) is a rare, severe neutrophilic skin disorder characterized by sudden widespread eruption of superficial sterile pustules with or without systemic inflammation. GPP flares can be life-threatening if untreated due to potential severe complications such as cardiovascular failure and serious infections. Currently, there are no GPP-specific therapies approved in the USA or Europe. Retinoids, cyclosporine, and methotrexate are the most commonly used non-biologic therapies for GPP. The evidence that supports the currently available treatment options is mainly based on case reports and small, open-label, single-arm studies. However, recent advances in our understanding of the pathogenic mechanisms of GPP and the identification of gene mutations linked to the disease have paved the way for the development of specific targeted therapies that selectively suppress the autoinflammatory and autoimmune mechanisms induced during GPP flares. Several biologic agents that target key cytokines involved in the activation of inflammatory pathways, such as tumor necrosis factor-α blockers and interleukin (IL)-17, IL-23, and IL-12 inhibitors, have emerged as potential treatments for GPP, with several being approved in Japan. The evidence supporting the efficacy of these agents is mainly derived from small, uncontrolled trials. A notable recent advance is the discovery of IL36RN mutations and the central role of IL-36 receptor ligands in the pathogenesis of GPP, which has defined key therapeutic targets for the disease. Biologic agents that target the IL-36 pathway have demonstrated promising efficacy in patients with GPP, marking the beginning of a new era of targeted therapy for GPP.

NK Cells Can Preferentially Target Prostate Cancer Stem-like Cells via the TRAIL/DR5 Signaling Pathway

Background: The occurrence of androgen-dependent prostate cancer mainly depends on prostate cancer stem cells. To reduce the risk of androgen-dependent prostate cancer, the direct elimination of prostate cancer stem cells is important, but an elimination strategy has not yet been established. A previous study showed that natural killer (NK) cells can preferentially target cancer stem cells in several solid tumors except prostate cancer. In this context, this study was undertaken to investigate if NK cells can selectively attack androgen-dependent prostate cancer stem cells. Methods: Prostate cancer stem-like cells were separated from an androgen-dependent prostate cancer cell line (LNCaP) using a three-dimensional culture system. LNCaP stem-like cells or LNCaP cells were co-cultured with human NK cells (KHYG-1) for 24–72 h, and cell viability was determined using the WST-8 method. The expression of each protein in the cell membrane was evaluated through FACS analysis, and mRNA levels were determined using real-time PCR. Results: KHYG-1 cells had more potent cytotoxicity against LNCaP stem-like cells than LNCaP cells, and the potency of the cytotoxicity was strongly related to the TRAIL/DR5 cell death pathway. Conclusion: NK cells can preferentially target prostate cancer stem-like cells via the TRAIL/DR5 pathway.

Adenosine and inflammation: it's time to (re)solve the problem

Resolution of inflammation requires proresolving molecular pathways triggered as part of the host response during the inflammatory phase. Adenosine and its receptors, which are collectively called the adenosine system, shape inflammatory cell activity during the active phase of inflammation, leading these immune cells toward a functional repolarization, thus contributing to the onset of resolution. Strategies based on the resolution of inflammation have shaped a new area of pharmacology referred to as 'resolution pharmacology' and in this regard, the adenosine system represents an interesting target to design novel pharmacological tools to 'resolve' the inflammatory process. In this review, we outline the role of the adenosine system in driving the events required for an effective transition from the proinflammatory phase to the onset and establishment of resolution.

Regulation of IL-17A-Producing Cells in Skin Inflammatory Disorders

This review focuses on the IL-17A family of cytokines produced by T lymphocytes and other immune cells and how they are involved in cutaneous pathogenic responses. It will also discuss cutaneous dysbiosis and FOXP3⁺ regulatory T cells in the context of inflammatory conditions linked to IL-17 responses in the skin. Specifically, it will review key literature on chronic mucocutaneous candidiasis and psoriasis.

Identification of Potential Biomarkers for Psoriasis by DNA Methylation and Gene Expression Datasets

DNA methylation (DNAm) plays an important role in the pathogenesis of psoriasis through regulating mRNA expressions. This study aimed to identify hub genes regulated by DNAm as biomarkers of psoriasis. Psoriatic skin tissues gene expression and methylation datasets were downloaded from Gene Expression Omnibus (GEO) database. Subsequently, multiple computational approaches, including immune infiltration analysis, enrichment analysis, protein-protein interaction (PPI) network establishment, and machine learning algorithm analysis (lasso, random forest, and SVM-RFE), were performed to analyze the regulatory networks, to recognize hub genes, and to clarify the pathogenesis of psoriasis. Finally, the hypermethylated genes were used to immune cell infiltration analysis, which revealed that psoriasis skin tissues were mainly composed of activated dendritic cells, resting mast cells, T follicular helper cells (cTfh), etc. Differentially expressed-methylated genes (DEMGs) were identified and partitioned into four subgroups and the 97 significantly hypermethylated and downregulated (hyper-down) genes accounted for the highest proportion (47%). Hyper-down genes were mainly enriched in glucose homeostasis, AMP-activated protein kinase (AMPK) signaling pathway, lipid storage disease, partial lipodystrophy, and insulin resistance. Furthermore, insulin receptor substrate 1 (IRS1), Rho guanine nucleotide exchange factor 10 (ARHGEF10) and retinoic acid induced 14 (RAI14) were identified as potential targets. These findings provided new ideas for future studies of psoriasis on the occurrence and the molecular mechanisms.

Surface AMP deaminase 2 as a novel regulator modifying extracellular adenine nucleotide metabolism

Adenine nucleotides represent crucial immunomodulators in the extracellular environment. The ectonucleotidases CD39 and CD73 are responsible for the sequential catabolism of ATP to adenosine via AMP, thus promoting an anti-inflammatory milieu induced by the "adenosine halo". AMPD2 intracellularly mediates AMP deamination to IMP, thereby both enhancing the degradation of inflammatory ATP and reducing the formation of anti-inflammatory adenosine. Here, we show that this enzyme is expressed on the surface of human immune cells and its predominance may modify inflammatory states by altering the extracellular milieu. Surface AMPD2 (eAMPD2) expression on monocytes was verified by immunoblot, surface biotinylation, mass spectrometry, and immunofluorescence microscopy. Flow cytometry revealed enhanced monocytic eAMPD2 expression after TLR stimulation. PBMCs from patients with rheumatoid arthritis displayed significantly higher levels of eAMPD2 expression compared with healthy controls. Furthermore, the product of AMPD2-IMP-exerted anti-inflammatory effects, while the levels of extracellular adenosine were not impaired by an increased eAMPD2 expression. In summary, our study identifies eAMPD2 as a novel regulator of the extracellular ATP-adenosine balance adding to the immunomodulatory CD39-CD73 system.

Glycyrrhizin improves the pathogenesis of psoriasis partially through IL-17A and the SIRT1-STAT3 axis

Background

The anti-inflammatory effect of glycyrrhizin has been widely recognized, while the specific mechanism of glycyrrhizin in psoriasis remains poorly understood.

Results

In the imiquimod-induced mouse model of psoriasis (IMD), we found that glycyrrhizin can substantially improve the adverse symptoms in mice. The hematoxylin-eosin staining results showed that glycyrrhizin can also improve the pathological state of skin cells in IMD mice. Using enzyme-linked immunosorbent assay (ELISA), we found that glycyrrhizin substantially inhibited the expression of IL-17A and IFN-γ in the serum of IMD mice. In order to simulate the effect of IL-17A on keratinocytes in psoriasis, we treated HaCaT cells with 100 ng/mL IL-17A (IL-17A-HaCaT cells) for 48 h. Then, using cell-counting kit-8 (CCK-8) and ELISA assays, we found that glycyrrhizin inhibited the proliferation of IL-17A-HaCaT cells and reversed the promotion of IL-6, CCL20, and TNF-α induced by IL-17A. Further, western blotting (WB) results indicated that glycyrrhizin promoted the expression of SIRT1 and inhibited the expression of STAT3 and phosphorylated STAT3 (p-STAT3). By treating IL-17A-HaCaT cells with EX-527 (a potent and selective inhibitor of SIRT1), combined with CCK-8 and WB experiments, we initially found that EX-527 inhibited the proliferation of IL-17A-HaCaT cells and promoted the expression of STAT3, p-STAT3, and acetylated STAT3 (a-STAT3). However, when glycyrrhizin was added at the same time, the proliferation of IL-17A-HaCaT cells increased, and the expression of STAT3, p-STAT3, and a-STAT3 reduced. We then knocked down the expression of SIRT1 via small interfering RNA in IL-17A-HaCaT cells, and the results were consistent with those of EX-527.

Conclusions

Together, these results indicated that glycyrrhizin improved psoriasis by inhibiting the expression of IL-17A and IFN-γ in vivo and suppressed the proliferation of IL-17A-HaCaT cells and the expression of STAT3, p-STAT3, and a-STAT3 by upregulating SIRT1 in vitro.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00421-z.

Rapamycin Alleviates 2,3,7,8-Tetrachlorodibenzo-p-dioxin-Induced Aggravated Dermatitis in Mice with Imiquimod-Induced Psoriasis-Like Dermatitis by Inducing Autophagy

Recently, the mTOR signaling has emerged as an important player in the pathogenesis of psoriasis. We previously found that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced psoriatic skin inflammation was related to the inhibition of autophagy in keratinocytes. However, the effects and detailed molecular mechanisms of the mTOR inhibitor rapamycin and TCDD on psoriasis in vivo remain to be elucidated. In this study, we aimed to evaluate the effects of rapamycin and TCDD on skin lesions in imiquimod (IMQ)-induced psoriasis using a mouse model. TCDD aggravated skin inflammation in an IMQ-induced psoriatic mouse model. Furthermore, TCDD increased the expression of aryl hydrocarbon receptor (AHR), CYP1A1, proinflammatory cytokines, oxidative stress markers (NADPH oxidase (Nox) 2, Nox4), and phosphorylated P65NF-ĸB, whereas the expression of autophagy-related factors and the antioxidant marker nuclear factor-erythroid 2-related factor 2 (NRF2) decreased. Rapamycin reduced the aggravated skin inflammation induced by TCDD and restored TCDD-induced autophagy suppression and the increase of AHR expression, oxidative stress, and inflammatory response in the skin lesions of a psoriatic mouse model. In conclusion, we demonstrated that rapamycin alleviates TCDD-induced aggravated dermatitis in mice with imiquimod-induced psoriasis-like dermatitis through AHR and autophagy modulation.

Metformin and omega-3 fish oil elicit anti-inflammatory effects via modulation of some dysregulated micro RNAs expression and signaling pathways in experimental induced arthritis

OBJECTIVE

Rheumatoid arthritis is a progressive inflammatory disease with multiple dysfunctional intracellular signaling pathways that necessitate new approaches for its management. Hence, the study aimed to inspect the ability of the combination therapy of metformin and omega-3 to modulate different signaling pathways and micro RNAs such as (miR-155, miR-146a and miR-34) as new targets in order to mitigate adjuvant-induced arthritis and compare their effect to that of methotrexate.

METHODS

Fourteen days post adjuvant injection, Sprague-Dawley rats were treated orally with metformin (200 mg/kg/day) and/or omega-3 (300 mg/kg/day) or intraperitoneally with methotrexate (2 mg/kg/week) for 4 weeks.

RESULTS AND CONCLUSION

All drug treatments amended the arthrogram score and hind paw swelling as well as decreased serum tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels. On the molecular level, all therapies activated phospho-5'adenosine monophosphate-activated protein kinase (p-AMPK) and protein phosphatase 2A (PP2A), while they inhibited phospho-mammalian target of rapamycin (p-mTOR), phospho-signal transducers and activators of transcription (p-STAT3), nuclear factor (NF)-κB p65 subunit, phosho38 mitogen-activated protein kinase (p38 MAPK) and phospho- c-Jun N-terminal kinase (p-JNK). In addition, they decreased the elevated expression level of miRNA-155, 146a and increased the expression level of miRNA-34 and they decreased the expression level of retinoic acid receptor related orphan receptor γT (RORγT) and increased that of fork head box P3 (FOXP3), correcting Th17/Treg cells balance. On most of the aforementioned parameters, the effect of the combination therapy was comparable to that of methotrexate, emphasizing that this combination possesses better additive anti-inflammatory effect than either drug when used alone. In addition, the combination was capable of normalizing the serum transaminases levels as compared to untreated group offering hepatoprotective effect and suggesting the possibility of its use as a replacement therapeutic strategy for MTX in rheumatoid arthritis.

Role of regulatory T cells in psoriasis pathogenesis and treatment

Psoriasis is a chronic inflammatory disease with a strong genetic component that can be triggered by environmental factors. Disease pathogenesis is mainly driven by type 1 and type 17 cytokine-producing cells which, in healthy individuals, are modulated by regulatory T cells (Tregs). Tregs play a fundamental role in immune homeostasis and contribute to the prevention of autoimmune disease by suppressing immune responses. In psoriasis, Tregs are impaired in their suppressive function leading to an altered T-helper 17/Treg balance. Although Treg dysfunction in patients with psoriasis is associated with disease exacerbation, it is unknown how they are functionally regulated. In this review, we discuss recent insights into Tregs in the setting of psoriasis with an emphasis on the effect of current treatments on Tregs and how already available therapeutics that modulate Treg frequency or functionality could be exploited for treatment of psoriasis.

Interleukin-9 serves as a key link between systemic inflammation and angiogenesis in psoriasis

BACKGROUND

Psoriasis is a T helper cell-mediated chronic immune-mediated inflammatory disease affecting mainly the skin, although systemic pathological effects are also observed. Cytokine-mediated interaction between T lymphocytes and keratinocytes lead to excessive proliferation of keratinocytes, which in turn leads to formation of a proinflammatory milieu and finally to psoriatic plaque formation.

AIM

To measure interleukin (IL)-9, IL-17 and vascular endothelial growth factor (VEGF) levels in patients with psoriasis compared with controls, and to evaluate the effect of methotrexate (MTX) monotherapy on the aforesaid cytokine levels in psoriasis.

METHODS

This cohort study included 54 patients with psoriasis and 54 age- and sex-matched healthy controls (HCs). IL-9, IL-17 and VEGF levels were measured by using commercially available ELISA kits. Patients with psoriasis who were on MTX monotherapy were followed up for a period of 3 months.

RESULTS

Patients with psoriasis had increased levels of IL-9, IL-17 and VEGF at baseline, compared with the HC group. After 3 months of MTX monotherapy, Psoriasis Area Severity Index (PASI), Dermatology Life Quality Index (DLQI) and levels of cytokines (IL-9, IL-17 and VEGF) were significantly decreased compared with baseline. PASI and DLQI at baseline also showed a positive correlation with IL-9, IL-17 and VEGF.

CONCLUSION

Our results suggest the existence of a proinflammatory milieu in psoriasis, with increased levels of IL-9, IL-17 and the proangiogenic growth factor VEGF, showing an increasing trend with increasing disease severity and impaired quality of life (QoL). MTX treatment helps to reduce levels of IL-9, IL-17 and VEGF, thereby limiting disease progression and improving QoL in psoriasis.

Methotrexate shows benefit in a subset of patients with severe hidradenitis suppurativa

BACKGROUND

Methotrexate is an immunomodulatory therapy that may offer benefit to patients with hidradenitis suppurativa (HS). Despite its theoretical advantages, there is a paucity of available data regarding long-term methotrexate use in patients with HS.

OBJECTIVE

This study aimed to assess whether methotrexate treatment leads to improvement in HS disease severity.

METHODS

We conducted an institutional review board-approved, single-center, retrospective chart review of patients with HS who were treated with methotrexate between 2000 and 2018. Primary outcome measurements included the HS Physician's Global Assessment (HS PGA), Hurley staging, abscess count, fistula count, and inflammatory nodule count.

RESULTS

A total of 29 patients were identified; 14 were excluded for reasons including never starting methotrexate and missing follow-up data. For remaining patients (n = 15), the average cumulative dose of methotrexate was 520.1 mg (range, 30-1665 mg) and the average length of treatment was 11.7 months (range, 1-38 months). Patients taking methotrexate as a primary therapy had a higher cumulative dose and length of treatment (520.13 mg; 14.6 months) compared with those taking biologics concomitantly (468.44 mg; 9.1 months). Patients using methotrexate as primary therapy demonstrated nonsignificant reductions in HS PGA, inflammatory nodule count, and abscess count. Patients on concomitant biologic therapy failed to demonstrate any change in HS PGA, inflammatory nodule count, and abscess count.

LIMITATIONS

Limitations of the study include its retrospective nature, small sample size, length of time on methotrexate between groups, and homogeneity of the patient population.

CONCLUSION

Methotrexate may represent an effective treatment option in older patients with lower body mass indices but fails to offer benefit in patients taking concurrent biologic therapy.

Metabolic Pathways That Control Skin Homeostasis and Inflammation

Keratinocytes and skin immune cells are actively metabolizing nutrients present in their microenvironment. This is particularly important in common chronic inflammatory skin diseases such as psoriasis and atopic dermatitis, characterized by hyperproliferation of keratinocytes and expansion of inflammatory cells, thus suggesting increased cell nutritional requirements. Proliferating inflammatory cells and keratinocytes express high levels of glucose transporter (GLUT)1, l-type amino acid transporter (LAT)1, and cationic amino acid transporters (CATs). Main metabolic regulators such as hypoxia-inducible factor (HIF)-1α, MYC, and mechanistic target of rapamycin (mTOR) control immune cell activation, proliferation, and cytokine release. Here, we provide an updated perspective regarding the potential role of nutrient transporters and metabolic pathways that could be common to immune cells and keratinocytes, to control psoriasis and atopic dermatitis.

Kaempferol attenuates imiquimod-induced psoriatic skin inflammation in a mouse model

Psoriasis is an immune-mediated inflammatory skin disease that mainly affects the skin barrier. Treatment for psoriasis mainly includes conventional immunosuppressive drugs. However, long-term treatment with global immunosuppressive agents may cause a variety of side effects, including nephrotoxicity and infections. Kaempferol, a natural flavonol present in various plants, is known to possess potent anti-inflammatory, anti-oxidant and anti-cancerous properties. However, it is unknown whether kaempferol is also anti-psoriatic. Here we established an imiquimod (IMQ)-induced psoriatic mouse model to explore the potential therapeutic effects of kaempferol on psoriatic skin lesions and inflammation. In this study, we demonstrated that treatment with kaempferol protected mice from developing psoriasis-like skin lesions induced by topical administration of IMQ. Kaempferol reduced CD3⁺ T cell infiltration and gene expression of major proinflammatory cytokines, including interleukin (IL)-6, IL-17A and tumor necrosis factor (TNF)-α, in the psoriatic skin lesion. It also down-regulated proinflammatory nuclear factor kappa B (NF-κB) signaling in the skin. The therapeutic effects were associated with a significant increase in CD4⁺ forkhead box protein 3 (FoxP3)⁺ regulatory T cell (T_reg ) frequency in the spleen and lymph nodes as well as FoxP3-positive staining in the skin lesion. Conversely, depletion of CD4⁺ CD25⁺ T_regs reversed the therapeutic effects of kaempferol on the skin lesion. Kaempferol also lowered the percentage of IL-17A⁺ CD4⁺ T cells in the spleen and lymph nodes of IMQ-induced psoriatic mice. Finally, kaempferol suppressed the proliferation of T cells in vitro and their mTOR signaling. Thus, our findings suggest that kaempferol may be a therapeutic drug for treating human psoriasis in the near future.

Betulinic acid suppresses Th17 response and ameliorates psoriasis-like murine skin inflammation

Psoriasis is a common inflammatory skin disease. Current treatment for psoriasis relies on conventional immunosuppressive agents. However, long-term treatment with global immunosuppression may cause various side effects. Thus, it is compelling to seek alternative drugs for treating psoriasis with potentially less side effects. Betulinic acid (BA) is a naturally occurring pentacyclic triterpene, an ingredient that originally exists in natural plants and lacks systemic toxicity. BA can regulate immunity with anti-fibrotic, anti-inflammatory and antioxidant properties. However, it's unknown whether BA has a therapeutic effect on psoriasis. The objectives of this study were to investigate whether BA attenuates psoriatic skin inflammation and to identify its mechanisms of action. A murine model of imiquimod-induced psoriasis was utilized to evaluate skin lesion while flow cytometry, immunohistochemistry, quantitative RT-PCR and Western blotting analyses were performed for immunoassays. We found that BA treatment alleviated psoriatic symptoms and inflammatory skin lesion. BA lowered the PASI scores, decreased epidermal thickness and reduced T cell infiltration in the skin lesion. Moreover, BA reduced the frequency of IL-17A-expressing CD4⁺ and γδ T cells in psoriatic mice, but did not alter CD4⁺FoxP3⁺ Treg frequency. BA also reduced IL-17A production but increased anti-inflammatory cytokine IL-10 level in serum of the psoriatic mice. Furthermore, BA inhibited gene expression of pro-inflammatory mediators in skin lesions, including RORγt, IL-17A, IL-6 and TNFα. Importantly, it suppressed NFκB signaling in the skin lesion. Finally, BA inhibited T cell proliferation and IL-17A production by CD4⁺ T-Cells in vitro. Thus, BA attenuates psoriasis and inhibits Th17 development.

Epidermal mTORC1 Signaling Contributes to the Pathogenesis of Psoriasis and Could Serve as a Therapeutic Target

Although modern biologics targeting different inflammatory mediators show promising therapeutic success, comprehensive knowledge about the molecular events in psoriatic keratinocytes that contribute to the pathogenesis and could serve as therapeutic targets is still scarce. However, recent efforts to understand the deregulated signal transduction pathways have led to the development of small molecule inhibitors e.g., tofacitinib targeting the Jak/Stat cascade that opens additional therapeutic options. Recently, the PI3-K/Akt/mTOR signaling pathway has emerged as an important player in the control of epidermal homeostasis. This review summarizes the current knowledge on the role of this pathway in the pathogenesis of psoriasis, especially the epidermal manifestation of the disease and discusses current approaches to target the pathway therapeutically.

Esculetin Ameliorates Psoriasis-Like Skin Disease in Mice by Inducing CD4+Foxp3+ Regulatory T Cells

Psoriasis is an autoimmune and inflammatory skin disease affecting around 2-3% of the world's population. Patients with psoriasis need extensive treatments with global immunosuppressive agents that may cause severe side effects. Esculetin, a type of coumarins, is an active ingredient extracted mainly from the bark of Fraxinus rhynchophylla, which has been used to treat inflammatory and autoimmune diseases in China. However, the antipsoriatic effects of esculetin have not been reported. In this study, we aimed to investigate the effects of esculetin on psoriatic skin inflammation in a mouse model and explored the potential molecular mechanisms underlying its action. We found that esculetin ameliorated the skin lesion and reduced PASI scores as well as weight loss in imiquimod-induced psoriasis-like mice, accompanied with weakened proliferation and differentiation of keratinocytes and T cell infiltration in esculetin-treated psoriatic mice. In addition, esculetin reduced the frequency of CD8⁺CD44^highCD62L^low effector T cells in psoriatic mice. In contrast, it increased the frequency of CD4⁺Foxp3⁺ Tregs in both lymph nodes and spleens of the psoriatic mice while promoting the differentiation of CD4⁺CD25^- T cells into CD4⁺Foxp3⁺ Tregs in vitro. Interestingly, depleting CD4⁺Foxp3⁺ Tregs largely reversed esculetin-mediated reduction in PASI scores, indicating that esculetin attenuates murine psoriasis mainly by inducing CD4⁺Foxp3⁺ Tregs. Furthermore, the mRNA levels of proinflammatory cytokines in the psoriatic mouse skin, including IL-6, IL-17A, IL-22, IL-23, TNF-α, and IFN-γ, were dramatically decreased by the treatment with esculetin. Finally, we found that esculetin inhibited the phosphorylation of IKKα and P65 in the psoriatic skin, suggesting that it inhibits the activation of NF-κB signaling. Thus, we have demonstrated that esculetin attenuates psoriasis-like skin lesion in mice and may be a potential therapeutic candidate for the treatment of psoriasis in clinic.