c-Jun N-terminal kinase (JNK)-phospho-c-JUN (ser63/73) pathway is essential for FOXP3 nuclear translocation in psoriasis

Biochanin A Ameliorates Imiquimod-Induced Psoriasis-Like Skin Inflammation in Mice by Modulating the NF-κB and MAPK Signaling Pathways

Psoriasis is a chronic skin inflammatory disorder characterized by the hyper-activation of the immune system and the over-proliferation of epidermal keratinocytes. This study aimed to investigate the anti-psoriatic activity of Biochanin A (BCA), a phytomolecule with known anti-inflammatory and anti-cancer properties, using the IMQ-induced psoriasis-like mouse model. Network pharmacology analysis was performed to investigate the targetability of Biochanin A (BCA) against psoriasis. Psoriasis-like skin inflammation was established using BALB/c mice by topical application of IMQ (5%). BCA cream (0.3%, 1%, 3%) was applied on the skin regions every day for 6 days. The skin phenotypes-erythema and scaling were scored every day. On the 7th day, skin tissues were collected for gene expression analysis, histopathological analysis, cytokine levels determination, and western blot analysis for signaling mechanisms. The network pharmacology analysis has identified 57 common targets between psoriasis and BCA. The topical application of IMQ induced a typical psoriasis-like skin phenotype including redness, skin thickening, and plaque formation. Upon BCA treatment, the psoriasis-like symptoms were significantly reduced in a dose-dependent manner. The targets identified by the network pharmacology (MMP9, EGFR, and PTGS2) and the pro-inflammatory cytokine gene expression were found to be significantly elevated in IMQ controls, and upon BCA treatment they were found significantly reduced. The release of cytokines linked to psoriasis (IL-17A and IL-23) were significantly reduced upon BCA treatment. Furthermore, our findings demonstrated that BCA treatment alleviated the psoriasis-like symptoms via modulating NF-κB and MAPK signaling pathways. Our results demonstrate the therapeutic potential of BCA against IMQ-induced psoriasis-like skin inflammation.

Natural Product-Derived Compounds Targeting Keratinocytes and Molecular Pathways in Psoriasis Therapeutics

Psoriasis is a chronic autoimmune inflammatory skin disorder that affects approximately 2-3% of the global population due to significant genetic predisposition. It is characterized by an uncontrolled growth and differentiation of keratinocytes, leading to the formation of scaly erythematous plaques. Psoriasis extends beyond dermatological manifestations to impact joints and nails and is often associated with systemic disorders. Although traditional treatments provide relief, their use is limited by potential side effects and the chronic nature of the disease. This review aims to discuss the therapeutic potential of keratinocyte-targeting natural products in psoriasis and highlight their efficacy and safety in comparison with conventional treatments. This review comprehensively examines psoriasis pathogenesis within keratinocytes and the various related signaling pathways (such as JAK-STAT and NF-κB) and cytokines. It presents molecular targets such as high-mobility group box-1 (HMGB1), dual-specificity phosphatase-1 (DUSP1), and the aryl hydrocarbon receptor (AhR) for treating psoriasis. It evaluates the ability of natural compounds such as luteolin, piperine, and glycyrrhizin to modulate psoriasis-related pathways. Finally, it offers insights into alternative and sustainable treatment options with fewer side effects.

Signaling pathways and targeted therapies for psoriasis

Psoriasis is a common, chronic, and inflammatory skin disease with a high burden on individuals, health systems, and society worldwide. With the immunological pathologies and pathogenesis of psoriasis becoming gradually revealed, the therapeutic approaches for this disease have gained revolutionary progress. Nevertheless, the mechanisms of less common forms of psoriasis remain elusive. Furthermore, severe adverse effects and the recurrence of disease upon treatment cessation should be noted and addressed during the treatment, which, however, has been rarely explored with the integration of preliminary findings. Therefore, it is crucial to have a comprehensive understanding of the mechanisms behind psoriasis pathogenesis, which might offer new insights for research and lead to more substantive progress in therapeutic approaches and expand clinical options for psoriasis treatment. In this review, we looked to briefly introduce the epidemiology, clinical subtypes, pathophysiology, and comorbidities of psoriasis and systematically discuss the signaling pathways involving extracellular cytokines and intracellular transmission, as well as the cross-talk between them. In the discussion, we also paid more attention to the potential metabolic and epigenetic mechanisms of psoriasis and the molecular mechanistic cascades related to its comorbidities. This review also outlined current treatment for psoriasis, especially targeted therapies and novel therapeutic strategies, as well as the potential mechanism of disease recurrence.

Pathogenesis, multi-omics research, and clinical treatment of psoriasis

Psoriasis is a common inflammatory skin disease involving interactions between keratinocytes and immune cells that significantly affects the quality of life. It is characterized by hyperproliferation and abnormal differentiation of keratinocytes and excessive infiltration of immune cells in the dermis and epidermis. The immune mechanism underlying this disease has been elucidated in the past few years. Research shows that psoriasis is regulated by the complex interactions among immune cells, such as keratinocytes, dendritic cells, T lymphocytes, neutrophils, macrophages, natural killer cells, mast cells, and other immune cells. An increasing number of signaling pathways have been found to be involved in the pathogenesis of psoriasis, which has prompted the search for new treatment targets. In the past decades, studies on the pathogenesis of psoriasis have focused on the development of targeted and highly effective therapies. In this review, we have discussed the relationship between various types of immune cells and psoriasis and summarized the major signaling pathways involved in the pathogenesis of psoriasis, including the PI3K/AKT/mTOR, JAK-STAT, JNK, and WNT pathways. In addition, we have discussed the results of the latest omics research on psoriasis and the epigenetics of the disease, which provide insights regarding its pathogenesis and therapeutic prospects; we have also summarized its treatment strategies and observations of clinical trials. In this paper, the various aspects of psoriasis are described in detail, and the limitations of the current treatment methods are emphasized. It is necessary to improve and innovate treatment methods from the molecular level of pathogenesis, and further provide new ideas for the treatment and research of psoriasis.

Insulin-binding protein-5 down-regulates the balance of Th17/Treg

The inflammatory response plays critical important role in tissue hemostasis. Our previous study showed insulin-binding protein-5 (IGFBP5) could enhance the regeneration of tissue defect under inflammation condition, but the function of IGFBP5 in controlling inflammation and regulating immune responses remains unclear. In present study, we studied the regulatory effect of IGFBP5 on T cell immune response in vitro, and the maintenance of Th17/Treg balance in vivo by using dextran sulfate sodium salt (DSS)-induced colitis in mice. The results showed that IGFBP5 inhibited the differentiation of CD4⁺ T cells into Th17 subset while promoted its differentiation into Treg subsets. Further results of animal experiments demonstrated that recombinant IGFBP5 reversed the imbalance of Th17/Treg and alleviated the severity of DSS-induced colitis. The percentage of Th17 cells decreased and the percentage of Treg cells increased in the inflamed colon tissue and mesenteric lymph nodes of mice with colitis after IGFBP5 treatment. Besides, pro-inflammatory cytokines such as TNF-α, IL-1β and IFN-γ in serum were suppressed after the treatment of IGFBP5. Moreover, the function of IGFBP5 in regulating Th17/Treg balance could be inhibited by the inhibitors of ERK or JNK pathway. In conclusion, all these data showed that IGFBP5 could regulate Th17/Treg balance via ERK or JNK pathways. The findings of our study provide a theoretical basis for the application of IGFBP5 in inflammatory diseases.

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

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

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

Inhibitory effect of IQ-1S, a selective c-Jun N-terminal kinase (JNK) inhibitor, on phenotypical and cytokine-producing characteristics in human macrophages and T-cells

c-Jun N-terminal kinase (JNK) is a critical mitogen activated protein kinase (MAPK) implicated in inflammatory processes, with IQ-1S (11H-indeno[1,2-b]quinoxalin-11-one oxime sodium salt) being a high-affinity JNK inhibitor with pronounced anti-inflammatory properties. Here, we studied direct effects of IQ-1S on phenotypical and cytokine-producing characteristics of activated human monocytes/macrophages and T cells in vitro. Purified monocyte/macrophage cells were activated by bacterial lipopolysaccharide (LPS, 1 μg/ml) for 24 h, while T cells were activated by particles conjugated with antibodies (Abs) against human CD2, CD3, and CD28 for 48 h. Treatment with IQ-1S (0.5-25 μМ) in the presence of LPS reduced percentages of CD197 (CCR7)-positive cells in macrophage cultures, without affecting CD16⁺ (FcγRIII, low-affinity Fc-receptor), CD119⁺ (interferon-γ receptor 1), and CD124⁺ (IL-4 receptor α-subunit) cells. In addition, IQ-1S reduced production of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-10 in macrophage cultures. In activated T cell cultures, IQ-1S decreased CD25⁺ cell numbers in both CD4-positive and CD4-negative T cell compartments. Central memory СD45RA^-/СD197⁺ and effector memory СD45RA^-/СD197^- T cells were more sensitive to IQ-1S-mediated suppression, as compared to naïve СD45RA⁺/СD197⁺ and terminally-differentiated effector СD45RA⁺/СD197^- T cells. IQ-1S also suppressed T-cell cytokine production (IL-2, interferon-ɣ, IL-4, and IL-10). Collectively, the results suggest that both human macrophage and T cells could be immediate cell targets for IQ-1S-based anti-inflammatory immunotherapy. IQ-1S-mediated suppressive effects were unlikely to be associated with macrophage/T helper polariation.

The JNK Signaling Pathway in Inflammatory Skin Disorders and Cancer

The c-Jun N-terminal kinases (JNKs), with its members JNK1, JNK2, and JNK3, is a subfamily of (MAPK) mitogen-activated protein kinases. JNK signaling regulates a wide range of cellular processes, including cell proliferation, differentiation, survival, apoptosis, and inflammation. Dysregulation of JNK pathway is associated with a wide range of immune disorders and cancer. Our objective is to provide a review of JNK proteins and their upstream regulators and downstream effector molecules in common skin disorders, including psoriasis, dermal fibrosis, scleroderma, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma.

JNK and phosphorylated Bcl-2 predict multiple sclerosis clinical activity and glatiramer acetate therapeutic response

In this study, we investigated the role of JNK and phospho-Bcl-2 as possible biomarkers of multiple sclerosis (MS) relapse and of glatiramer acetate (GA) therapeutic response in relapsing-remitting MS patients. We enrolled a cohort of 15 GA-treated patients and measured the expression of JNK1, JNK2, phospho-JNK and phospho-Bcl-2 through Western blotting of lysates from peripheral blood mononuclear cells collected at 0, 3, 6, and 12 months after initiating GA therapy. We found significantly higher levels of JNK1 p54 and JNK2 p54 and significantly lower levels of p-Bcl-2 in relapse patients and in GA non-responders. By using receiver operating characteristic analysis, we found that the probability of accurately detecting relapse and response to GA was: 92% and 75.5%, respectively, for JNK1 p54 and 86% and 94.6%, respectively, for p-Bcl-2. Our data suggest that JNK1 and p-Bcl-2 could serve as potential biomarkers for MS relapse and the therapeutic response to GA.

Small-molecule compounds target paraptosis to improve cancer therapy

According to its different occurrence mechanism, programmed cell death (PCD) is divided into apoptosis, autophagy, necrosis, paraptosis and so on. Paraptosis is morphologically different from apoptosis and autophagy, which exhibit cytoplasmic vacuolation derived from the ER, independent of caspase, absence of apoptotic morphology. Recent researches have implied that a variety of small molecule compounds, such as celastrol, curcumin, can induce paraptosis-associated cell death as the reagent to enhance anti-cancer activity. A better understanding of paraptosis will lay the foundation to develop new therapeutic strategies to treat human cancers that make full use of small-molecule compounds.

C19, a C-terminal peptide of CKLF1, decreases inflammation and proliferation of dermal capillaries in psoriasis

Psoriasis is a chronic inflammatory autoimmune disease with undefined etiology. Chemokine-like factor 1 (CKLF1), a human cytokine that is a functional ligand for CCR4, displays chemotactic activities in a wide spectrum of leukocytes and plays an important role in psoriasis development. In previous study, our laboratory found that the expression of CKLF1 increased in psoriatic lesions. C19 as a CKLF1's C-terminal peptide has been reported to exert inhibitory effects on a variety of diseases. However, the protective roles of C19 in endothelial cells proliferation and inflammatory cells chemotaxis remain elusive in psoriasis. In this study we examined the protective effect of C19 on both the cellular model and the animal model. The effects of C19 on endothelial cells proliferation and inflammatory cells chemotaxis were investigated in cultured human umbilical vein endothelial cells (HUVECs) and imiquimod-induced psoriasiform inflammation of BALB/c mice based on techniques including immunohistochemical analysis, quantitative real-time PCR (qRT-PCR), western blot, transwell, and EdU assay. This study shows that CKLF1-C19 significantly protects against psoriasis by inhibiting the infiltration of inflammatory cells and proliferation of microvascular cells, possibly via inhibiting MAPK pathways.

Ultraviolet irradiation promotes FOXP3 transcription via p53 in psoriasis

The decrease of forkhead box P3-positive (FOXP3 + ) regulatory T cells (Tregs) causes an immune imbalance with effector T cells in psoriasis. Previous studies have demonstrated that in addition to its known effects on keratinocytes and effector T cells, ultraviolet (UV) irradiation alleviates psoriasis via the upregulation of FOXP3 + Tregs. However, the mechanism is unclear. Here, we found that FOXP3 + T cells were increased in psoriatic lesions after UVB irradiation (t' = 3.7006, P < 0.01), as determined by immunohistochemical staining. In addition, the levels of FOXP3 and p53, one of the downstream targets of UV irradiation, showed accordant changes after UV irradiation. Experiments that used a MAPK inhibitor, p53 mutant cell lines, p53 inhibitor and p53 shRNA showed a decrease in FOXP3 levels, suggesting that p53 is required for UV-induced FOXP3 transcription. Next, we demonstrated that there are two binding sites for p53 on FOXP3 by informatics tools, a dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay. One binding site (-1771 to -1583) is located at the promoter region and is adjacent to a previously reported p53-binding region in breast cancer cells. The other (+3845 to +4042) is located within the first intron and has not been previously reported. Our study demonstrated that FOXP3 is regulated, at least in part, by the binding of p53 to several binding sites in the promoter and intron regions following UV irradiation in psoriasis. It will be helpful to further clarify the regulatory mechanism of FOXP3 transcription and to provide new insights into the mechanisms that mediate the effects of UV irradiation in autoimmune skin disorders.

Anti-Inflammatory Effects and Joint Protection in Collagen-Induced Arthritis after Treatment with IQ-1S, a Selective c-Jun N-Terminal Kinase Inhibitor

c-Jun N-terminal kinases (JNKs) participate in many physiologic and pathologic processes, including inflammatory diseases. We recently synthesized the sodium salt of IQ-1S (11H-indeno[1,2-b]quinoxalin-11-one oxime) and demonstrated that it is a high-affinity JNK inhibitor and inhibits murine delayed-type hypersensitivity. Here we show that IQ-1S is highly specific for JNK and that its neutral form is the most abundant species at physiologic pH. Molecular docking of the IQ-1S syn isomer into the JNK1 binding site gave the best pose, which corresponded to the position of cocrystallized JNK inhibitor SP600125 (1,9-pyrazoloanthrone). Evaluation of the therapeutic potential of IQ-1S showed that it inhibited matrix metalloproteinase 1 and 3 gene expression induced by interleukin-1β in human fibroblast-like synoviocytes and significantly attenuated development of murine collagen-induced arthritis (CIA). Treatment with IQ-1S either before or after induction of CIA resulted in decreased clinical scores, and joint sections from IQ-1S-treated CIA mice exhibited only mild signs of inflammation and minimal cartilage loss compared with those from control mice. Collagen II-specific antibody responses were also reduced by IQ-1S treatment. By contrast, the inactive ketone derivative 11H-indeno[1,2-b]quinoxalin-11-one had no effect on CIA clinical scores or collagen II-specific antibody titers. IQ-1S treatment also suppressed proinflammatory cytokine and chemokine levels in joints and lymph node cells. Finally, treatment with IQ-1S increased the number of Foxp3(+)CD4(+)CD25(+) regulatory T cells in lymph nodes. Thus, IQ-1S can reduce inflammation and cartilage loss associated with CIA and can serve as a small-molecule modulator for mechanistic studies of JNK function in rheumatoid arthritis.

Recent advances in atopic dermatitis and psoriasis: genetic background, barrier function, and therapeutic targets

Atopic dermatitis (AD) and psoriasis are common inflammatory skin diseases. Although clinical pictures of these two diseases are quite different, they share some common pathological backgrounds such as barrier dysfunction and enhanced IL-22 expression. To explain the clinical differences of the diseases, it has been proposed that Th2/Th22-polarized immune status together with an attenuated Th17 axis may cause insufficient induction of antimicrobial peptides and more severe barrier dysfunction in AD. While skin barrier dysfunction is commonly seen in AD and psoriasis, a Th2-dominant cytokine milieu down-regulates immunity against infections, which are commonly seen in lesional skin of AD. In the era of biologics, increase in the understanding or new discoveries of molecules involved in the development of various diseases will instantly lead to a new therapeutic strategy. In this review, we give an overview of recent advances in AD and psoriasis, especially on genetic background, barrier function, and therapeutic targets.