Role of interferon regulatory factor-mediated signaling in psoriasis

Formononetin attenuates psoriasiform inflammation by regulating interferon signaling pathway

BACKGROUND

Psoriasis is a long-lasting, inflammatory, continuous illness caused through T cells and characterized mainly by abnormal growth and division of keratinocytes. Currently, corticosteroids are the preferred option. However, prolonged use of traditional topical medication can lead to adverse reactions and relapse, presenting a significant therapeutic obstacle. Improved alternative treatment options are urgently required. Formononetin (FMN) is a representative component of isoflavones in Huangqi (HQ) [Astragalus membranaceus (Fisch.) Bge.]. It possesses properties that reduce inflammation, combat oxidation, inhibit tumor growth, and mimic estrogen. Although FMN has been shown to ameliorate skin barrier devastation via regulating keratinocyte apoptosis and proliferation, there are no reports of its effectiveness in treating psoriasis.

OBJECTIVE

Through transcriptomics clues and experimental investigation, we aimed to elucidate the fundamental mechanisms underlying FMN's action on psoriasis.

MATERIALS AND METHODS

Cell viability was examined using CCK8 assay in this study. The results of analysis of differentially expressed genes (DEGs) between FMN-treated HaCaT cells and normal HaCaT cells using RNA-sequencing (RNA-seq) were presented on volcano plots and heatmap. Enrichment analysis was conducted on DEGs using Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO), and results were validated through RT-qPCR verification. After 12 days of FMN treatment in psoriasis mouse model, we gauged the PASI score and epidermis thickness. A variety of techniques were used to assess FMN's effectiveness on inhibiting inflammation and proliferation related to psoriasis, including RT-qPCR, HE staining, western blot, and immunohistochemistry (IHC).

RESULTS

The findings indicated that FMN could suppress the growth of HaCaT cells using CCK8 assay (with IC50 = 40.64 uM) and 20 uM FMN could reduce the level of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) to the greatest extent. FMN-treated HaCaT cells exhibited 985 up-regulated and 855 down-regulated DEGs compared to normal HaCaT cells. GO analysis revealed that DEGs were linked to interferon (IFN) signaling pathway. Furthermore, FMN improved pathological features, which encompassed decreased erythema, scale, and thickness scores of skin lesions in psoriasis mouse model. In vivo experiments confirmed that FMN down-regulated expression of IFN-α, IFN-β, IFN-γ, decreased secretion of TNF-α and IL-17 inflammatory factors, inhibited expression of IFN-related chemokines included Cxcl9, Cxcl10, Cxcl11 and Cxcr3 and reduced expression of transcription factors p-STAT1, p-STAT3 and IFN regulatory factor 1 (IRF1) in the imiquimod (IMQ) group.

CONCLUSIONS

In summary, these results suggested that FMN played an anti-inflammatory and anti-proliferative role in alleviating psoriasis by inhibiting IFN signaling pathway, and FMN could be used as a potential therapeutic agent.

Insight into the role of IRF7 in skin and connective tissue diseases

Interferons (IFNs) are signalling proteins primarily involved in initiating innate immune responses against pathogens and promoting the maturation of immune cells. Interferon Regulatory Factor 7 (IRF7) plays a pivotal role in the IFNs signalling pathway. The activation process of IRF7 is incited by exogenous or abnormal nucleic acids, which is followed by the identification via pattern recognition receptors (PRRs) and the ensuing signalling cascades. Upon activation, IRF7 modulates the expression of both IFNs and inflammatory gene regulation. As a multifunctional transcription factor, IRF7 is mainly expressed in immune cells, yet its presence is also detected in keratinocytes, fibroblasts, and various dermal cell types. In these cells, IRF7 is critical for skin immunity, inflammation, and fibrosis. IRF7 dysregulation may lead to autoimmune and inflammatory skin conditions, including systemic scleroderma (SSc), systemic lupus erythematosus (SLE), Atopic dermatitis (AD) and Psoriasis. This comprehensive review aims to extensively elucidate the role of IRF7 and its signalling pathways in immune cells and keratinocytes, highlighting its significance in skin-related and connective tissue diseases.

3,3'-Diindolylmethane inhibits Th17 cell differentiation via impairing IRF-7-mediated plasmacytoid dendritic cell activation in imiquimod-induced psoriasis mice

Psoriasis is a paradigmatic condition characterised by a heightened autoimmune response and chronic inflammation. However, the exact nature and the pathological causes behind it are still unknown. Growing evidence suggest dysregulated cytokine network as a result of over-activated T cells and plasmacytoid dendritic cells (pDCs) as the critical drivers in the development of psoriasis. In the present study, we aimed to investigate the therapeutic efficacy of 3,3'-diindolylmethane (DIM) on pDC activation and Th17 cell development in imiquimod (IMQ)-induced psoriasis mice. Our in vitro research investigated the IRF-7 signalling in pDCs that explained the reduced expression of the transcription factor IRF-7 responsible for pDC activation as a result of DIM treatment. Concurrently, DIM treatment decreased the release of Th17 cell polarising cytokines (IFN-α, IL-23, and IL-6) by pDCs which validated a reduction in differentiated pathogenic Th17 cell population and associated cytokine IL-17A in IMQ-induced psoriatic mice. Thus, our recent findings provide therapeutic evidence in targeting the early potential contributors for psoriasis treatment by preventing IRF-7-mediated pDC activation and Th17 cell development in IMQ-induced psoriasis mice.

Network pharmacology and molecular docking to explore the mechanism of a clinical proved recipe for external use of clearing heat and removing dampness in the treatment of immune-related cutaneous adverse events

Immune-related cutaneous adverse events (ircAEs) will undermine the patients' quality of lives, and interrupt the antitumor therapy. A clinical proved recipe for external use of clearing heat and removing dampness (Qing-Re-Li-Shi Formula, hereinafter referred to as "QRLSF") is beneficial to the treatment of ircAEs in clinical practice. Our study will elucidate the mechanism of QRLSF against ircAEs based on network pharmacology and molecular docking. The active components and corresponding targets of QRLSF were collected through traditional Chinese medicine systems pharmacology database. GeneCards, online Mendelian inheritance in man, and pharmacogenomics knowledgebase were used to screen the targets of ircAEs. The intersecting targets between drug and disease were acquired by venn analysis. Cytoscape software was employed to construct "components-targets" network. Search tool for the retrieval of interacting genes/proteins database was applied to establish the protein-protein interaction network and then its core targets were identified. Gene ontology and Kyoto encyclopedia of genes and genomes analysis was performed to predict the mechanism. The molecular docking verification of key targets and related phytomolecules was accomplished by AutoDock Vina software. Thirty-nine intersecting targets related to QRLSF against ircAEs were recognized. The analysis of network clarified 5 core targets (STAT3, RELA, TNF, TP53, and NFKBIA) and 4 key components (quercetin, apigenin, luteolin, and ursolic acid). The activity of QRLSF against ircAEs could be attributed to the regulation of multiple biological effects via multi-pathways (PI3K-Akt pathway, cytokine-cytokine receptor interaction, JAK-STAT pathway, chemokine pathway, Th17 cell differentiation, IL-17 pathway, TNF pathway, and Toll-like receptor pathway). The binding activities were estimated as good level by molecular docking. These discoveries disclosed the multi-component, multi-target, and multi-pathway characteristics of QRLSF against ircAEs, providing a new strategy for such medical problem.