Psoriasis induced by topical imiquimod

Unconjugated bilirubin and its derivative ameliorate IMQ-induced psoriasis-like skin inflammation in mice by inhibiting MMP9 and MAPK pathway

Psoriasis is a chronic immune-mediated inflammatory skin disease that involves dysregulated proliferation of keratinocytes. Psoriatic skin lesions are characterized by redness, thickness, and scaling. The interleukin axis of IL-23/IL-17 is critically involved in the development of human psoriasis. Imiquimod (IMQ), an agonist of TLR7 is known to induce psoriatic-like skin inflammation in mice. The topical application of IMQ induces systemic inflammation with increased proinflammatory cytokines in serum and secondary lymphoid organs. Further, matrix metalloproteases (MMPs) have been implicated in the pathophysiology of psoriatic-like skin inflammation. The increased MMP9 activity and gene expression of proinflammatory cytokines in IMQ-induced psoriatic skin is mediated by the activation of the MAPK pathway. Moreover, the increased expression of neutrophil-specific chemokines confirmed the infiltration of neutrophils at the site of psoriatic skin inflammation. In contrast, expression of IL-10, an anti-inflammatory cytokine gene expression is reduced in IMQ-treated mice skin. Topical application of unconjugated bilirubin (UCB) and its derivative dimethyl ester of bilirubin (BD1) on IMQ-induced psoriatic mice skin significantly mitigated the symptoms of psoriasis by inhibiting the activity of MMP9. Further, UCB and BD1 reduced neutrophil infiltration as evidenced by decreased myeloperoxidase (MPO) activity and reduced gene expression of proinflammatory cytokines, and neutrophil-specific chemokines. Apart from these modulations UCB and BD1 reduced MAPK phosphorylation and upregulated anti-inflammatory cytokines. To conclude, UCB and BD1 immunomodulated the psoriatic skin inflammation induced by IMQ in mice by inhibiting neutrophil mediated MMP9, decreased proinflammatory cytokines gene expression and modulating the MAPK pathway.

Transcriptomic profiling of TLR-7-mediated immune-challenge in zebrafish embryos in the presence and absence of glucocorticoid-induced immunosuppression

Although numerous studies imply a correlation between chemical contamination and an impaired immunocompetence of wildlife populations, the assessment of immunomodulatory modes of action is currently not covered in the regulatory requirements for the approval of new substances. This is not least due to the complexity of the immune system and a lack of standardised methods and validated biomarkers. To tackle this issue, in this study, the transcriptomic profiles of zebrafish embryos were analysed in response to the immunosuppressive compound clobetasol propionate, a synthetic glucocorticoid, and/or the immunostimulatory compound imiquimod (IMQ), a TLR-7 agonist. Using IMQ, known for its potential to induce psoriasis-like effects in mice and human, this study additionally aimed at evaluating the usability of the zebrafish embryo model as an alternative and 3R conform system for the IMQ-induced psoriasis mouse model. Our study substantiates the suitability of previously proposed genes as possible biomarkers for immunotoxicity, such as socs3, nfkbia, anxa1c, fkbp5 and irg1l. Likewise, however, our findings indicate that these genes may be less suitable to distinguish a suppressive from stimulating fashion of action. In contrast, based on a differential regulation in opposite direction in response to both compounds, krt17, rtn4a, and1, smhyc1 and gmpr were identified as potential novel biomarkers with said power to differentiate. Observed IMQ-induced alterations in the expression of genes previously associated with the pathogenesis of psoriasis such as krt17, nfkbia, parp1, pparg, nfil3-6, per2, stat4, klf2, rtn4a, anxa1c and nr1d2 indicate the inducibility of psoriatic effects in the zebrafish embryo. Our work contributes to the establishment of an approach for a 3R-compliant investigation of immunotoxic mechanisms of action in aquatic vertebrates. The validated and newly identified biomarker candidates of specific immunotoxic effects can be used in future studies in the context of environmental hazard assessment of substances or also for human-relevant immunotoxicological questions.

Regulation of psoriasis, colitis, and the intestinal microbiota by clusterin

Psoriasis, a chronic and systemic inflammatory disorder characterized by activation of the interleukin (IL)-23/IL-17 axis, may be associated with the intestinal microbiota through the so-called "gut-skin axis." Clusterin is a glycoprotein ubiquitously distributed in mammalian tissues; however, its role in psoriasis is unclear. Therefore, we evaluated the role of clusterin in psoriatic skin inflammation, systemic inflammation, and colitis using a murine model of IMQ-induced psoriasis. In IMQ-treated clusterin-knockout (clusterin-/-) mice, the expressions of inflammatory cytokines in clusterin-silenced human keratinocytes and intestinal microbial composition were analyzed. We also examined clusterin expression in the skin tissues of patients with psoriasis. IMQ-induced psoriatic skin inflammation is suppressed in clusterin-/- mice. Long-term administration of IMQ induced systemic inflammation and colitis; however, both were alleviated by the genetic deletion of clusterin. Genetic silencing of clusterin in human keratinocytes inhibited the production of inflammatory cytokines involved in the initiation and progression of psoriasis. The composition of the intestinal microbiota in IMQ-treated clusterin-/- and wild-type mice was different. Genetic deletion of clusterin suppressed the increase in the Firmicutes/Bacteroidetes (F/B) ratio. Skin tissues of patients with psoriasis showed high clusterin expression. In conclusion, inhibition of clusterin decreased psoriatic skin inflammation, systemic inflammation, colitis, and altered the F/B ratio in an IMQ-induced murine psoriasis model.

Rare Cutaneous Side Effects of Imiquimod: A Review on Its Mechanisms, Diagnosis, and Management

As an immune-response modifier, imiquimod can bind to Toll-like receptors on immune cells and enhance innate and adaptive immune responses, exerting potential antitumor and antiviral effects, which led to its approval by the US Food and Drug Administration for the treatment of actinic keratosis, superficial basal cell carcinomas, and anogenital warts, and to its off-label use in treating many other benign and malignant dermatoses. Although topical administration of imiquimod has been considered well tolerated, an increasing number of cutaneous and noncutaneous side effects are being reported as its clinical applications expand. This review primarily focuses on rare cutaneous side effects. To the best of our knowledge, this is the first article to summarize the mechanism, diagnosis, and management of rare cutaneous side effects of imiquimod, which may help to heighten awareness among physicians, especially dermatologists, about potential imiquimod-induced cutaneous side effects.

Diagnosis and Management of Dermatologic Adverse Events from Systemic Melanoma Therapies

The advent of protein kinase inhibitors and immunotherapy has profoundly improved the management of advanced melanoma. However, with these therapeutic advancements also come drug-related toxicities that have the potential to affect various organ systems. We review dermatologic adverse events from targeted (including BRAF and MEK inhibitor-related) and less commonly used melanoma treatments, with a focus on diagnosis and management. As immunotherapy-related toxicities have been extensively reviewed, herein, we discuss injectable talimogene laherparepvec and touch on recent breakthroughs in the immunotherapy space. Dermatologic adverse events may severely impact quality of life and are associated with response and survival. It is therefore essential that clinicians are aware of their diverse presentations and management strategies.

Curcumin Alleviates Epidermal Psoriasis-Like Dermatitis and IL-6/STAT3 Pathway of Mice

Background

To further investigate why curcumin (CUR) can attenuate psoriasis-like dermatitis of mice.

Methods and Results

Sixteen mice were randomized into four groups. The control group used carrier cream, and the model and the CUR group were applied with topical 5% imiquimod in the naked mice skin once a day for 6 days (62.5 mg/day/mice). Meanwhile, the control and model mice were given the same dose of saline by oral means, while mice in the CUR groups received oral drug doses of 50 and 100 mg/kg once a day for 6 days, respectively. CUR could largely improve imiquimod-induced lesions of mice. By using the ELISA and qPCR, we found that the protein and mRNA levels of epidermal TNF-α and IL-6 were inhibited by CUR. The phosphorylation levels of STAT3 and its downstream associated protein levels (eg, Cyclin D1, Bcl-2 and Pim1) in skin tissues of different groups were also inhibited by CUR. Furthermore, the results of immunohistochemistry also showed the repressed effect of CUR for the expression of TNF-α, IL-6 and p-STAT3 in psoriasis-like lesions of mice.

Conclusion

CUR can effectively ameliorate the featured lesions of psoriasis mice, which may be closely associated with the involvement of IL-6/STAT3 signaling.

Procyanidin B2 3,3''-di-O-gallate ameliorates imiquimod-induced skin inflammation by suppressing TLR7 signaling through the inhibition of endosomal acidification in dendritic cells

The excessive activation of abnormal T helper 17 (Th17) cells and dendritic cells (DCs) in the dermis and epidermis causes severe inflammation of the skin. Toll-like receptor 7 (TLR7)-located in the endosomes of DCs-recognizes nucleic acids from pathogens as well as imiquimod (IMQ), which plays a crucial role in the pathogenesis of skin inflammation. Procyanidin B2 3,3''-di-O-gallate (PCB2DG), a polyphenol, has been reported to suppress the excessive production of proinflammatory cytokines from T cells. The aim of this study was to demonstrate the inhibitory effect of PCB2DG on skin inflammation and TLR7 signaling in DCs. In vivo studies showed that the clinical symptoms of dermatitis were markedly improved by the oral administration of PCB2DG in mouse dermatitis model caused by IMQ application, accompanied by the suppression of excessive cytokine secretion in the inflamed skin and spleen. In vitro, PCB2DG significantly decreased cytokine production in TLR7- or TLR9 ligand-stimulated bone marrow-derived dendritic cells (BMDCs), suggesting that PCB2DG suppresses endosomal toll-like receptors (TLR) signaling in DCs. The activity of endosomal TLRs depends on endosomal acidification, which was significantly inhibited by PCB2DG in BMDCs. The addition of cAMP, an accelerator of endosomal acidification, abrogated the inhibitory effect of cytokine production by PCB2DG. These results provide a new insight into developing functional foods, including PCB2DG, to improve the symptoms of skin inflammation through the suppression of TLR7 signaling in DCs.

Immunotherapy for keratinocyte cancers. Part II: Identification and management of cutaneous side effects of immunotherapy treatments

Keratinocytic cancers (KCs), specifically cutaneous squamous cell and basal cell carcinomas, can respond to topical, intralesional, or systemic immunotherapies, but cutaneous adverse events (CAEs) may occur. Understanding these risks, early recognition of these CAEs, and effective treatment may enable patients to continue their anticancer immunotherapies without dose impact. Immune checkpoint inhibitor-related CAEs after KCs can have multiple clinical presentations, with specific observed types including psoriasis and bullous pemphigoid. Cutaneous toxicities can require biopsies to confirm the diagnosis, especially in patients who are not responsive to topical or oral steroids, since the selection of biologic drugs depends on accurate diagnosis. Different types of CAEs from immune checkpoint inhibitors have been associated with different oncologic outcomes in various primary cancer types, and this remains to be determined for KC patients. CAE characterization and management after immune checkpoint inhibitors in KC patients is a rapidly growing field that needs specific and prospective studies.

Preclinical study models of psoriasis: State-of-the-art techniques for testing pharmaceutical products in animal and nonanimal models

Local and systemic treatments exist for psoriasis, but none can do more than control its symptoms because of its numerous unknown mechanisms. The lack of validated testing models or a defined psoriatic phenotypic profile hinders antipsoriatic drug development. Despite their intricacy, immune-mediated diseases have no improved and precise treatment. The treatment actions may now be predicted for psoriasis and other chronic hyperproliferative skin illnesses using animal models. Their findings confirmed that a psoriasis animal model could mimic a few disease conditions. However, their ethical approval concerns and inability to resemble human psoriasis rightly offer to look for more alternatives. Hence, in this article, we have reported various cutting-edge techniques for the preclinical testing of pharmaceutical products for the treatment of psoriasis.

A cutback in Imiquimod cutaneous toxicity; comparative cutaneous toxicity analysis of Imiquimod nanotransethosomal gel with 5% marketed cream on the BALB/c mice

Herein, Imiquimod (IMQ) was incorporated in nanotransethosomes (nTES) to develop the IMQ-nTES nano-drug delivery system. IMQ-nTES was optimized using 23 factorial design. The optimized formulation was expressed with a particle size of 192.4 ± 1.60 nm, Poly-dispersibility of 0.115 ± 0.008, and IMQ percent entrapment efficiency of 91.05 ± 3.22%. Smooth and round morphology of IMQ-nTES vesicles was confirmed by TEM micrographs. Moreover, FTIR results have shown drug-excipient compatibility. The IMQ-nTES was laden inside the low molecular weight chitosan gel, which exhibited easy application, spreadability and no irritation to the applied skin. The release pattern has clearly exhibited improved dissolution properties of IMQ with the provision of the sustain release pattern. Higher IMQ content was deposited in deeper epidermis and dermis with IMQ-nTES gel, in contrast to ALDARA. In vivo, comparative toxicity study on BALB/c mice has shown significantly reduced (p < 0.001) psoriatic area severity index (PASI) score and less increment in ear thickness. Epidermal hyperplasia was an obvious finding with ALDARA which was, providentially, minimal in IMQ-nTES gel-treated skin. FTIR analysis of skin tissue has shown an enhancement of lipid and protein content in the ALDARA group, however, in the IMQ-nTES group no such change was observed. With ALDARA application, CD4+ T-cells and constitutive NF-κβ expression were significantly elevated, in comparison to the IMQ-nTES gel treated group. Moreover, the adequate expression of IFN-γ and cytotoxic CD8+ T-cells were suggesting the preserved IMQ efficacy with IMQ-nTES gel. Quantification of cutaneous as well as systemic inflammatory markers has also suggested the reduced psoriatic potential of IMQ-nTES gel. In essence, IMQ-nTES gel can be a suitable alternative to ALDARA owing to its better safety profile.

RNF115 Inhibits the Post-ER Trafficking of TLRs and TLRs-Mediated Immune Responses by Catalyzing K11-Linked Ubiquitination of RAB1A and RAB13

The subcellular localization and intracellular trafficking of Toll-like receptors (TLRs) critically regulate TLRs-mediated antimicrobial immunity and autoimmunity. Here, it is demonstrated that the E3 ubiquitin ligase RNF115 inhibits the post-endoplasmic reticulum (ER) trafficking of TLRs and TLRs-mediated immune responses by catalyzing ubiquitination of the small GTPases RAB1A and RAB13. It is shown that the 14-3-3 chaperones bind to AKT1-phosphorylated RNF115 and facilitate RNF115 localizing on the ER and the Golgi apparatus. RNF115 interacts with RAB1A and RAB13 and catalyzes K11-linked ubiquitination on the Lys49 and Lys61 residues of RAB1A and on the Lys46 and Lys58 residues of RAB13, respectively. Such a modification impairs the recruitment of guanosine diphosphate (GDP) dissociation inhibitor 1 (GDI1) to RAB1A and RAB13, a prerequisite for the reactivation of RAB proteins. Consistently, knockdown of RAB1A and RAB13 in Rnf115^+/+ and Rnf115^-/- cells markedly inhibits the post-ER and the post-Golgi trafficking of TLRs, respectively. In addition, reconstitution of RAB1A^K49/61R or RAB13^K46/58R into Rnf115^+/+ cells but not Rnf115^-/- cells promotes the trafficking of TLRs from the ER to the Golgi apparatus and from the Golgi apparatus to the cell surface, respectively. These findings uncover a common and step-wise regulatory mechanism for the post-ER trafficking of TLRs.

Pinocembrin Reduces Keratinocyte Activation and Ameliorates Imiquimod-Induced Psoriasis-like Dermatitis in BALB/c Mice through the Heme Oxygenase-1/Signal Transducer and Activator of Transcription 3 Pathway

Psoriasis is an autoimmune disease characterized by chronic skin inflammation and excessive keratinocyte proliferation. The itchy, scaly, and erythematous lesions present on psoriatic skin negatively affect patients' quality of life. Pinocembrin is a flavonoid present in propolis, fruits, and vegetables. It exerts neuroprotective effects and was used for treating ischemic stroke in a human clinical trial. However, the effects of pinocembrin on psoriasis have never been examined. In this study, we evaluated the effects of pinocembrin on human HaCaT keratinocytes and BALB/c mice with imiquimod- (IMQ-) induced psoriatic dermatitis. In interferon-γ- (IFN-γ-) activated HaCaT cells, pinocembrin reduced the expression of inflammatory cytokines, namely, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and keratinocyte proliferation markers, namely, keratin (K)16, K17, and Ki-67. The mechanism underlying these inhibitory effects involved the regulation of the heme oxygenase- (HO-) 1/signal transducer and activator of transcription (STAT) 3 pathway. In the IMQ-induced psoriatic dermatitis mouse model, the topical application of pinocembrin significantly ameliorated the Skin Psoriasis Area and Severity Index score, epidermal thickness, inflammation, hyperplasia, hyperkeratosis, and cluster of differentiation (CD) 4⁺ T-cell infiltration. Expression of the inflammatory cytokines and keratinocyte proliferation markers in dorsal skin was significantly decreased in the pinocembrin-treated group. Meanwhile, in lesional skin, the expression of HO-1 was upregulated, but that of phospho-STAT3 (pSTAT3) was downregulated. Collectively, our results indicated the therapeutic potential of pinocembrin. Additional studies are warranted to evaluate its clinical benefits in patients with psoriasis.

Allosteric inhibition of SHP2 uncovers aberrant TLR7 trafficking in aggravating psoriasis

Psoriasis is a complex chronic inflammatory skin disease with unclear molecular mechanisms. We found that the Src homology‐2 domain‐containing protein tyrosine phosphatase‐2 (SHP2) was highly expressed in both psoriatic patients and imiquimod (IMQ)‐induced psoriasis‐like mice. Also, the SHP2 allosteric inhibitor SHP099 reduced pro‐inflammatory cytokine expression in PBMCs taken from psoriatic patients. Consistently, SHP099 significantly ameliorated IMQ‐triggered skin inflammation in mice. Single‐cell RNA sequencing of murine skin demonstrated that SHP2 inhibition impaired skin inflammation in myeloid cells, especially macrophages. Furthermore, IMQ‐induced psoriasis‐like skin inflammation was significantly alleviated in myeloid cells (monocytes, mature macrophages, and granulocytes)—but not dendritic cells conditional SHP2 knockout mice. Mechanistically, SHP2 promoted the trafficking of toll‐like receptor 7 (TLR7) from the Golgi to the endosome in macrophages by dephosphorylating TLR7 at Tyr1024, boosting the ubiquitination of TLR7 and NF‐κB‐mediated skin inflammation. Importantly, Tlr7 point‐mutant knock‐in mice showed an attenuated psoriasis‐like phenotype compared to wild‐type littermates following IMQ treatment. Collectively, our findings identify SHP2 as a novel regulator of psoriasis and suggest that SHP2 inhibition may be a promising therapeutic approach for psoriatic patients.

Deciphering the mechanism of Fang-Ji-Di-Huang-Decoction in ameliorating psoriasis-like skin inflammation via the inhibition of IL-23/Th17 cell axis

ETHNOPHARMACOLOGICAL RELEVANCE

In the theory of traditional Chinese medicine (TCM), the etiology of psoriasis is assigned to damp-heat internal depression, blood poisoning, Yin deficiency and loss of nourishment. Fang-Ji-Di-Huang-Decoction (FJDH), a well-known Chinese traditional formula, is recorded in Synopsis of the Golden Chamber (in the Eastern Han Dynasty). This decoction is composed of dried roots of Rehmannia glutinosa (Gaertn.) DC., dried roots of Stephania tetrandra S. Moore, roots of Saposhnikovia divaricata (Turcz.) Schischk., dried twigs of Cinnamomum cassia (L.) J. Presl and dry roots and rhizomes of Glycyrrhiza uralensis Fisch. FJDH has the function of clearing heat, removing dampness, and nourishing blood. Therefore, in modern medical theory, FJDH can regulate the infiltration of inflammatory cells and the secretion of inflammatory cytokines in the process of psoriasis.

AIM OF THE STUDY

This study evaluated whether FJDH treated psoriasis and its specific mechanism for the efficacy in mice. At the same time, it clarified s what important role of the copperware played s in the curative effect of FJDH.

METHODS AND MATERIALS

We used imiquimod (IMQ) to induce psoriasis-like skin inflammation in mice. Mice were treated with imiquimod for one week, and FJDH was given by intragastric administration one week in advance. Record the weight change and psoriasis Area and Severity Index (PASI) score of the mouse during the whole process to assess the severity of psoriasis were recored mouse. Hematoxylin-eosin staining was used to evaluate skin tissue structure change. Immunohistochemistry was performed to observe the expressions of Ki67 and proliferating cell nuclear antigen (PCNA) in skin tissue. In order to further explore the mechanism of FJDH in the treatment of psoriasis, we used network pharmacology to predict the therapeutic target. TCMSP and Uniprot were used to collect compounds and genes of FJDH. Genecards was used for obtaining genes of psoriasis. String was used to analyze the relationship between genes. Metascape was used for gene enrichment and pathway prediction. Using molecular biological detection methods, we verified whether FJDH could regulate Interleukin 17 signaling pathway and T helper cell 17 (Th17) cell differentiation. Flow cytometry was used to detect Th17 cell differentiation in mouse spleen. Quantitative Real-time PCR was used to detect mRNA expression of IL-17 signaling pathway-related inflammatory factors in mouse skin tissues. UPLC-Triple TOF-MS/MS and Phenol-Sulphate colorimetry were used to explore the main components of FJDH, and further elaborate the mechanism of FJDH in the treatment of psoriasis.

RESULTS

FJDH with copper was found to improve psoriasis-related pathological symptoms in a dose-dependent manner, possibly by inhibiting IL-23/Th17 cell axis and reducing inflammatory cytokines such as IL-17A, IL-17F, IL-22 and TNF-α. Furthermore, R. glutinosa polysaccharide in FJDH was the main substance that exerted the drug effect and it work by forming a complex with copper. Experimental data proved that Rehmannia glutinosa polysaccharide and copper complex had the same pharmacological activity and therapeutic effect as FJDH.

CONCLUSIONS

FJDH may attenulated imiquimod-induced psoriasis-like skin inflammation in mice by inhibiting IL-23/Th17 cell axis. The material basis for the therapeutic effect may be the formation of complexes between the polysaccharides of R. glutinosa and copper in FJDH to produce the effect. These findings suggest that FJDH can be used as an effective Chinese medicine to treat psoriasis.

Exacerbation of generalized plaque psoriasis after tuberculin test

Koebner phenomenon, also known as isomorphic response, is the appearance of active skin lesions in sites of epidermal injury. This manifestation is characteristic of different dermatological diseases, such as lichen planus, vitiligo and psoriasis. We present the case of a psoriatic patient who experienced Koebner phenomenon after Mantoux test, followed by eruption of generalized plaque psoriasis.

Co-delivery of methotrexate and nicotinamide by cerosomes for topical psoriasis treatment with enhanced efficacy

Psoriasis is an immune-mediated skin disorder that affects populations worldwide. Methotrexate (MTX) is a cytotoxic drug with powerful anti-proliferative and anti-inflammatory effects that has gained prominence in treating inflammatory diseases including psoriasis. However, low solubility and side effects through oral administration hinder its systemic application. In this study, we developed a novel niosomes based on ceramide (cerosomes) to co-deliver MTX and nicotinamide (NIC), i.e., MTX/NIC cerosomes, for topically treating psoriasis with the aim to enhancing the efficacy and reducing the toxicity. NIC significantly solublized MTX by forming hydrogen bonds with MTX. In vitro and in vivo permeation studies showed that the cerosomes significantly promoted drug permeation through and retention in the skin, and the enhancing mechanism was clarified by Fourier transform infraredand Raman spectroscopy. MTX/NIC cerosomes exhibited strong anti-proliferation effect on lipopolysaccharide- irritated HaCaT cells by arresting the cell cycle at S phase and inducing apoptosis. Importantly, compared to MTX oral administration, topical application of MTX/NIC cerosomes on imiquimod (IMQ)-induced psoriatic mouse model exhibited a superior performance in ameliorating skin lesions, reducing spleen index and epidermal thickness, and downregulating the mRNA expression levels of proinflammatory cytokines including TNFα, IL-23, IL-17A, IL-6, IL-1β, and IL-22. Taken together, MTX/NIC cerosomes is a promising approach for psoriasis topical treatment.

Molecular and histopathological profiling of imiquimod induced dermatosis in Swiss Wistar rats: contribution to the rat model for novel anti-psoriasis treatments

Imiquimod (IMQ) induced human-like psoriasis in mice has been shown to be effective in testing and development of novel treatments. The IMQ psoriasis model has become widely used animal model, however, it is not completely characterized in different rat strains. We aimed to evaluate IMQ and betamethasone treatment for induction and reversal of psoriatic lesions on macroscopic, histological, genetic as well as cytokines and chemokines activation levels. Wistar rats were treated topically with IMQ. Adopted Psoriasis Area Severity Index (PASI) was calculated at the baseline, after the IMQ-symptoms induction and after betamethasone-symptoms reversal. Systematic effects were studied on cytokines and chemokines levels in plasma. Skin biopsy was taken to assess histological symptoms and selected inflammatory cytokines and receptors genes expression levels. Reversal of skin lesions, after betamethasone treatment, was significant (p = 0.03). Histological differences between untreated and IMQ-treated skin were significant for some markers (p < 0.05) though not significantly decreased by betamethasone treatment. Fourteen genes were significantly up-regulated after the IMQ and four genes were down-regulated after skin lesions reversal by betamethasone. This work provides new insights on biological effects of imiquimod induced psoriasis and its reversal by betamethasone treatment in Wistar rats. It also contributes to general knowledge of the rat model usage for testing of novel anti-psoriasis drugs.

OVOL1 Regulates Psoriasis-Like Skin Inflammation and Epidermal Hyperplasia

Psoriasis is a common inflammatory skin disease characterized by aberrant inflammation and epidermal hyperplasia. Molecular mechanisms that regulate psoriasis-like skin inflammation remain to be fully understood. Here, we show that the expression of Ovol1 (encoding ovo-like 1 transcription factor) is upregulated in psoriatic skin, and its deletion results in aggravated psoriasis-like skin symptoms following stimulation with imiquimod. Using bulk and single-cell RNA sequencing, we identify molecular changes in the epidermal, fibroblast, and immune cells of Ovol1-deficient skin that reflect an altered course of epidermal differentiation and enhanced inflammatory responses. Furthermore, we provide evidence for excessive full-length IL-1α signaling in the microenvironment of imiquimod-treated Ovol1-deficient skin that functionally contributes to immune cell infiltration and epidermal hyperplasia. Collectively, our study uncovers a protective role for OVOL1 in curtailing psoriasis-like inflammation and the associated skin pathology.

ZnO NPs delay the recovery of psoriasis-like skin lesions through promoting nuclear translocation of p-NFκB p65 and cysteine deficiency in keratinocytes

BACKGROUND

This study aimed to evaluate the safety of applying zinc oxide nanoparticles (ZnO NPs) to pathological skin. The majority of previous studies confirmed the safety of applying ZnO NPs to normal skin. However, we know very little about the risks of using sunscreen, cosmetics and topical drugs containing ZnO NPs for individuals with skin diseases.

RESULTS

ZnO NPs passed through gaps between keratinocytes and entered stratum basale of epidermis and dermis in imiquimod-induced psoriasis-like skin lesions. Application of a ZnO NP-containing suspension for 3 connective days delayed the healing of the epidermal barrier; increased the expression levels of inflammatory cytokines; promoted keratinocyte apoptosis and disturbed redox homeostasis. In TNF-α-stimulated HaCaT cells, QNZ and JSH-23 (NFκB inhibitors) blocked ZnO NP-induced inflammation. JSH-23 and NAC (a precursor of cysteine) inhibited ZnO NP-induced nuclear translocation of p-NFκB p65, cysteine deficiency and apoptosis. Additionally, ZnO NPs decreased CD98 level in main pathway and failed to activate transsulfuration pathway in cysteine biosynthesis.

CONCLUSIONS

ZnO NPs can enter psoriasis-like skin lesions and promote inflammation and keratinocyte apoptosis through nuclear translocation of p-NFκB p65 and cysteine deficiency. This work reminds the public that ZnO NPs have harmful effects on the recovery of inflammatory skin diseases.

Role of interferon regulatory factor-mediated signaling in psoriasis

Psoriasis is a chronic inflammatory disease that involves both the innate and adaptive immune systems. Type I interferons (IFNs), the production of which is partially regulated by toll-like receptors (TLRs), play an important role in the pathogenesis of psoriasis, especially psoriasis caused by skin trauma, known as the Koebner phenomenon. IFN regulatory factors (IRFs) function in both innate and adaptive immune responses, and their effect is associated with the regulation of type I IFNs. In this review, we focus on recent advances in understanding the expression of TLRs, IRFs, and type I IFNs in psoriasis. We also highlight the interplay among TLRs, IRFs, and type I IFNs.

Possible Role of Lysine Demethylase 2A in the Pathophysiology of Psoriasis

Background

Psoriasis is a common chronic inflammatory skin disease. The development of psoriasis is dependent on many intercellular events such as innate immunity and T cell-mediated inflammation. Furthermore, genetic factors are strongly implicated in the pathophysiology of psoriasis. Although a variety of susceptible genes are identified, it is likely that many important genes remain undisclosed.

Objective

The aim of this study is to investigate the possible role of lysine demethylase 2A (KDM2A) in the pathophysiology of psoriasis.

Methods

We examined the expression of KDM2A using a well established imiquimod-induced psoriasiform dermatitis model.

Results

Immunohistochemistry analysis showed that expression of KDM2A was increased in imiquimod-induced psoriasiform dermatitis. Consistent with this result, KDM2A level was markedly increased in the epidermis of psoriatic patient. When keratinocytes were stimulated with TLR3 agonist poly(I:C), KDM2A was increased at both the mRNA and protein levels. Poly(I:C) increased the expression of psoriasis-related cytokines including tumor necrosis factor-α, interleukin-8, and CCL20, and KDM2A inhibitor daminozide enhanced the poly(I:C)-induced cytokine expression. Finally, topical co-application of imiquimod and daminozide exacerbated the imiquimod-induced psoriasiform dermatitis.

Conclusion

Together, these results suggest that KDM2A is increased to negatively regulate the inflammatory reaction of epidermal keratinocytes in psoriasis.

Imiquimod does not elicit inflammatory responses in the skin of the naked mole rat (Heterocephalus glaber)

Objective

Naked mole rat (Heterocephalus glaber) has recently attracted interest in biomedical research due to its exceptional longevity, cancer resistance and tolerance to potentially harmful conditions or stimuli. Given its unique attributes, this study was designed to characterize inflammatory skin reactions of this animal to topical application of imiquimod, a toll-like receptor 7 and 8 agonist that triggers psoriasis-like skin reaction.

Results

Imiquimod did not cause the expected psoriasis-like skin changes. There was no epidermal thickening and a straight epidermo-dermal boundary was maintained. There was no parakeratosis and the granular layer of epidermis was well formed. In the dermis, there was no leukocyte infiltration. This points to an exceptional nature of inflammatory/immune responses of this animal, but the mechanism could not be explained by our results. Naked mole rat could be a valuable negative model for studying psoriasis and other inflammatory skin conditions but as a prerequisite, there is need for further investigations to establish the mechanisms behind its lack of response to imiquimod.

The influence of interferon on healthy and diseased skin

Type I interferons (IFNs) are an immunomodulatory class of cytokines that serve to protect against viral and bacterial infection. In addition, mounting evidence suggests IFNs, particularly type I but also IFNγ, are important to the pathogenesis of autoimmune and inflammatory skin diseases, such as cutaneous lupus erythematosus (CLE). Understanding the role of IFNs is relevant to anti-viral responses in the skin, skin biology, and therapeutics for these IFN-related conditions. Type I IFNs (α and β) are produced by recruited inflammatory cells and by the epidermis itself (IFNκ) and have important roles in autoimmune and inflammatory skin disease. Here, we review the current literature utilizing a PubMed database search using terms [interferon/IFN/type I IFN AND lupus/ cutaneous lupus/CLE/dermatomyositis/Sjogrens/psoriasis/lichen planus/morphea/alopecia areata/vitiligo] with a focus on the role of IFNs in basic keratinocyte biology and their implications in the cutaneous autoimmune and inflammatory diseases: cutaneous lupus erythematosus, dermatomyositis, Sjogren's syndrome, psoriasis, lichen planus, alopecia areata and vitiligo. We provide information about genes and proteins induced by IFNs and how downstream mechanisms relate to clinical disease.

Indoleamine 2,3-Dioxygenase 2 Deficiency Exacerbates Imiquimod-Induced Psoriasis-Like Skin Inflammation

Indoleamine 2,3-dioxygenase 1 (IDO1) is an enzyme known to suppress immune responses, and several reports have showed that it is associated with psoriasis. IDO2 is an isoform of IDO1, recently identified as a catalytic enzyme in the tryptophan-kynurenine pathway, which is expressed in dendritic cells and monocytes. The expression of IDO2 in immune cells suggests that IDO2 may contribute to immune functions. However, the role of IDO2 in the pathogenesis of psoriasis remains unclear. In this study, to elucidate the role of IDO2 in psoriasis, we assessed imiquimod (IMQ)-induced psoriasis-like dermatitis in IDO2 knockout (KO) mice. Skin inflammation, evaluated by scoring erythema, scaling, and ear thickness, was significantly worse in the IDO2 KO mice than in the wild-type (WT) mice. The mRNA expression levels of TNF-α, IL-23p19, and IL-17A, key cytokines involved in the development of psoriasis, were also increased in the IDO2 KO mice. Furthermore, immunohistochemistry revealed that the number of Ki67-positive cells in the epidermis and CD4-, CD8-, and IL-17-positive lymphocytes infiltrating the dermis were significantly increased in the IDO2 KO mice. These results suggest that IDO2 might decrease IL-17 expression, thereby resulting in the suppression of skin inflammation in IMQ-induced psoriasis-like dermatitis.

A Rationally Designed Micellar Nanocarrier for the Delivery of Hydrophilic Methotrexate in Psoriasis Treatment

Methotrexate (MTX) is broadly applied in the clinic for the treatments of cancers and autoimmune diseases. Targeted delivery of MTX is attractive to improve its efficacy and reduce off-target toxicity. However, MTX encapsulation in nanoparticle is challenging due to its high water solubility. We rationally designed a well-defined telodendrimer (TD) nanocarrier based on MTX structure to sequester it in nanoparticles. Riboflavin (Rf) and positive charges groups were precisely conjugated on TD to form multivalent hydrogen bonds, π-π stacking and electrostatic interactions with MTX. A reverse micelle approach was developed to preset MTX and TD interactions in the core of micelles, which ensures the effective MTX loading upon dispersion into aqueous solution. As results, MTX loading capacity reaches over 20% (w/w) in the optimized nanocarrier with the particle size of 20-30 nm. The nanoformulations sustain the release of MTX in a controlled manner and exhibit excellent hemocompatibility. The in vitro cellular uptake of MTX was significantly improved by the nanoformulations. The potency of MTX nanoformulations is comparable to the free MTX in cytotoxicity. A psoriasis-like skin inflammation model was induced in mouse by imiquimod (IMQ) stimulation. MTX nanoformulations improved the psoriasis targeting and exhibited a superior long-lasting efficacy in reducing skin inflammation compared with the free MTX in psoriasis treatment.

CpG ODN D35 improves the response to abbreviated low-dose pentavalent antimonial treatment in non-human primate model of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) affects the lives of 0.7–1 million people every year causing lesions that take months to heal. These lesions can result in disfiguring scars with psychological, social and economic consequences. Antimonials are the first line of therapy for CL, however the treatment is lengthy and linked to significant toxicities; further, its efficacy is variable and resistant parasites are emerging. Shorter or lower dose antimonial treatment regimens, which would decrease the risk of adverse events and improve patient compliance, have shown reduced efficacy and further increase the risk emergence of antimonial-resistant strains. The progression of lesions in CL is partly determined by the immune response it elicits, and previous studies showed that administration of immunomodulatory type D CpG ODNs, magnifies the immune response to Leishmania and reduces lesion severity in nonhuman primates (NHP) challenged with Leishmania major or Leishmania amazonensis. Here we explored whether the addition of a single dose of immunomodulating CpG ODN D35 augments the efficacy of a short-course, low-dose pentavalent antimonial treatment regimen. Results show that macaques treated with D35 plus 5mg/kg sodium stibogluconate (Sb^V) for 10 days had smaller lesions and reduced time to re-epithelization after infection with Leishmania major. No toxicities were evident during the studies, even at doses of D35 10 times higher than those used in treatment. Critically, pentavalent antimonial treatment did not modify the ability of D35 to induce type I IFNs. The findings support the efficacy of D35 as adjuvant therapy for shorter, low dose pentavalent antimonial treatment.

Cutaneous leishmaniasis is a devastating disease that affects close to a million people every year. Its clinical presentation ranges from small uncomplicated lesions that heal over a few months to debilitating large chronic or recurring lesions that result in disfigurement, stigma, and economic loss. Antimonials are the first line treatment for cutaneous leishmaniasis in most countries, but the lengthy treatment schedules, significant associated toxicities, and the emergence of resistant strains, require the development of alternative strategies. As the immune response is a key determinant of disease course, immunomodulatory therapies could be harnessed to act in concert with antimonials to improve the safety and efficacy of CL treatment. Synthetic oligonucleotide D35 selectively activates plasmacytoid dendritic cells and was previously shown to reduce the severity of L. major and L. amazonensis lesions in rhesus macaques, but its activity in combination with antimonials was unknown. Our studies show that a single subcutaneous dose of innate immune modulator D35 improved the response to a low-dose abbreviated antimonial course, reducing the severity of the lesions and accelerating healing in primates. No toxicities were evident with D35 at doses ten-fold higher than the effective dose. The studies suggest that the combined therapy strategy shows clinical promise.

Murine models of psoriasis and its applications in drug development

Psoriasis is an autoimmune skin disease which characteristic of a well-demarcated, erythematous, raised lesion with silvery-white dry scale. Although the mechanism of psoriasis has not been fully understood so far, much progress has been made in understanding many of its complex potential mechanism, particularly the crucial role of the IL-23/Th17 axis. There are a large number of psoriasis models that reflect the complexity of the psoriasis mechanisms. In this review, we summarize various psoriasis mouse models, detail the features and molecular mechanisms of these mouse models, and discuss their strengths and limitations for psoriasis research. The development of mouse models of psoriasis provide an important basis for studying psoriasis pathogenesis and antipsoriatic drugs development. Therefore, the application of various psoriasis mouse models in antipsoriatic drug development are also discussed.

Management of keratinocyte carcinoma - Special considerations in the elderly

Keratinocyte carcinomas (KCs) are now an epidemic in The United States of America, especially in elderly patients. KCs, including basal cell carcinoma and squamous cell carcinoma, can lead to disfigurement and occasionally death. However, the lower mortality rate associated with KC compared with melanoma allows for increased flexibility in the selection of treatment. Flexibility in treatment is particularly important in the elderly given that this patient population often has medical comorbidities that should be considered. These patients may have multiple KCs, higher risk tolerance to recurrence, and different concerns about cosmetic outcomes compared with their younger counterparts. We review treatment options for KCs and how the selection of each option may affect the elderly patient.

Fenoldopam mesylate for treating psoriasis: A new indication for an old drug

Fenoldopam, a highly selective dopamine receptor agonist, is available in clinics as Corlopam™ i.v. for the management of severe hypertension. Recent reports demonstrate its anti-proliferative activity in vitro in a dose dependent manner. However, stability issues of the drug due to its susceptibility to oxidation, pH sensitivity, poor transdermal flux, and the barrier properties of skin present challenges to develop a topical formulation of fenoldopam. The aim of the present study is to suggest a stable topical formulation of fenoldopam for the treatment of psoriasis. Water washable ointment and glycerin-based carbopol anhydrous gel of fenoldopam intended for topical delivery were prepared and evaluated in vitro and in vivo. Results from pH dependent stability studies suggest the necessity to maintain acidic pH in final formulations. The presence of an acidic adjuster in ointment and unneutralised carbopol dispersion of anhydrous gel maintain the desired acidic environment in the formulations. Stability studies of prepared formulations performed for 90 days indicate that the drug remains stable in formulations. In vivo studies demonstrate the applicability of the formulations for better skin penetration, skin compliance, and photosafety. Efficacy studies using an imiquimod induced psoriasis model confirm the promising application of developed fenoldopam topical formulations for psoriasis.

Loading of water-insoluble celastrol into niosome hydrogels for improved topical permeation and anti-psoriasis activity

Psoriasis is a severe disfiguring skin disease affecting approximately 3% of people worldwide and negatively affecting their daily lives. The pathogenesis of psoriasis is complicated, and typical therapeutic strategies for psoriasis mainly focus on anti-inflammation. Considering the side effects, withdrawal rebound, high cost, and many other disadvantages of existing treatments, we developed a new topical therapeutic formulation consisting of niosomes loaded with celastrol, a triterpenoid extracted from Tripterygium. Celastrol niosomes were prepared by the thin film hydration method and probe sonication. The niosomes were composed of Span 20, Span 60, and cholesterol at a weight ratio of 3:1:1. The particle size of the niosomes was approximately 147 nm, with yield of up to 90%. Celastrol niosomes showed improved in vitro permeation ability compared to the raw drug. In our in vivo study, celastrol niosomes effectively alleviated erythema and scaling on the dorsal skin of psoriasis mouse models. Spleen weight and the levels of cytokines, including IL-22, IL-23, and IL-17, decreased after the treatment, indicating the high therapeutic potential of this formulation for psoriasis. In conclusion, encapsulation of celastrol by niosomes increased the water-solubility and permeation of celastrol into the skin, significantly improving its anti-psoriasis activity in mice.

Liquid crystalline nanoreservoir releasing a highly skin-penetrating berberine oleate complex for psoriasis management

Aim: The current work highlighted preparation of highly penetrating liquid crystalline nanoparticulates (LCNPs) reservoir of a solubility modified berberine oleate (Brb-OL) complex for effective psoriasis management. Materials & methods: Brb-OL-loaded LCNPs (Brb-OL-LCNPs) were prepared using hydrotrope method. Results: The proposed Brb-OL-LCNPs showed a particle size of 137 ± 3.7 nm and negative ζ-potential (-38 ± -5.85 mV). Brb-OL-LCNPs showed a threefold increase in the drug accumulated within rat skin and around tenfold increase in the drug permeation compared with crude Brb. In vivo studies revealed that topical application of Brb-OL-LCNPs hydrogel significantly alleviated psoriasis symptoms and reduced the levels of psoriatic inflammatory cytokines. Conclusion: Formulating Brb-OL in the LCNPs controlled the release, retention and permeation of the drug across skin layers, which are of prime importance for psoriasis management.

IL-23- and Imiquimod-Induced Models of Experimental Psoriasis in Mice

Genome-wide association studies have found that polymorphisms in genes for IL-23 and its receptor are important in psoriasis, and blocking IL-23 is an effective therapy in the disease. The use of Aldara^™ , a cream that contains the TLR7 and TLR8 agonist imiquimod (IMQ), was found to exacerbate psoriasis in some patients with pre-existing disease. Intradermal injections of IL-23 and topical application of Aldara/IMQ induce skin inflammation in mice with features similar to psoriasis-including epidermal hyperplasia and accumulation of inflammatory cells in epidermis and dermis-which is mediated by IL-17A, IL-22, and other factors implicated in the human disease. Consequently, these models can be used in preclinical studies to investigate the molecular and cellular pathogenesis of psoriasis, as well as in the evaluation of potential therapies. This article provides detailed methodologies for creating and evaluating the IL-23- and Aldara/IMQ-induced mouse models of psoriasis. The article also provides a protocol for analyzing skin leukocytes by flow cytometry. © 2019 by John Wiley & Sons, Inc.

Comparison of normal versus imiquimod-induced psoriatic skin in mice for penetration of drugs and nanoparticles

Background

As an immune-mediated skin disease, psoriasis encounters therapeutic challenges on topical drug development due to the unclear mechanism, and complicated morphological and physiological changes in the skin.

Methods

In this study, imiquimod-induced psoriatic mouse skin (IMQ-psoriatic skin) was chosen as the in vitro pathological model to explore the penetration behaviors of drugs and nanoparticles (NPs).

Results

Compared with normal skin, significantly higher penetration and skin accumulation were observed in IMQ-psoriatic skin for all the three model drugs. When poorly water-soluble curcumin was formulated as NPs that were subsequently loaded in gel, the drug’s penetration and accumulation in both normal and IMQ-psoriatic skins were significantly improved, in comparison with that of the curcumin suspension. Interestingly, the NPs’ size effect, in terms of their penetration and accumulation behaviors, was more pronounced for IMQ-psoriatic skin. Furthermore, by taking three sized FluoSpheres^® as model NPs, confocal laser scanning microscopy demonstrated that the penetration pathways of NPs no longer followed the hair follicles channels, instead they were more widely distributed in the IMQ-psoriatic skin.

Conclusion

In conclusion, the alternation of the IMQ-psoriatic skin structure will lead to the enhanced penetration of drug and NPs, and should be considered in topical drug formulation and further clinical practice for psoriasis therapy.

Topical heat shock protein 70 prevents imiquimod-induced psoriasis-like inflammation in mice

Psoriasis is a chronic inflammatory skin disease with systemic manifestations and potential genetic etiology. The newest treatments utilize antibodies against one of several cytokines known to underlie the inflammatory signaling molecules that produce the skin and systemic symptoms. However, these agents must be regularly injected, and they may compromise the normal responses of the immune system. Furthermore, they do not address the causes of the abnormal immunoregulatory responses of the disease because the etiology is not yet completely understood. In this short-term treatment study, the potential anti-inflammatory activity of an alfalfa-derived Hsp70-containing skin cream (aHsp70) was tested on imiquimod (IMQ)-induced psoriasis-like lesions in wild-type mice. Treatment of the mice with the aHsp70 skin cream simultaneously with the imiquimod application mitigated the induction of psoriatic-like lesions and correlated with altered expression of various skin cytokines.

Comprehensive, Multimodal Characterization of an Imiquimod-Induced Human Skin Inflammation Model for Drug Development

Imiquimod (IMQ) is often used as a topical challenge agent to provoke local skin inflammation. The objective of this study was to develop and refine a rapid, temporary, and reversible human skin inflammation model with IMQ for application in clinical drug development. A randomized, vehicle‐controlled, open‐label, dose‐ranging study was conducted in 16 healthy male subjects. IMQ (5 mg) was applied once daily for 72 hours under occlusion to intact skin (n = 8) or tape stripped (TS) skin (n = 8). Although IMQ alone induced limited effects, TS+IMQ treatment showed larger responses in several domains, including erythema and perfusion (P < 0.0001), mRNA expression of inflammatory markers (P < 0.01), and inflammatory cell influx compared with vehicle. In conclusion, a rapid, human IMQ skin inflammation challenge model was successfully developed with a clear benefit of TS prior to IMQ application. Future interaction studies will enable proof‐of‐pharmacology of novel compounds targeting the innate immune system.

UC-1V150, a potent TLR7 agonist capable of activating macrophages and potentiating mAb-mediated target cell deletion

Toll-like receptors (TLR) are critical mediators of the immune system with their activation linked to infection, inflammation and the pathogenesis of immune diseases including autoimmunity and cancer. For this reason, over the last 2 decades, TLR and their associated signalling pathways have been targeted therapeutically to enhance innate and adaptive immunity. Several TLR ligands, both endogenous and synthetic are at various phases of clinical testing, and new ligands are continually emerging. Agonists of TLR7 are known immune response modifiers, simultaneously stimulating several cell types, resulting in immune cell activation and cytokine and chemokine release. The immune stimulating properties of the TLR7 agonist Imiquimod has also been exploited for use in the treatment of malignant superficial tumours of the skin. Here, we investigated a novel TLR7 agonist UC-1V150 and demonstrate it activates both human and mouse myeloid cells in vitro and in vivo, to deliver potent FcγR-mediated engulfment of opsonized target cells.

Maresin-1 suppresses imiquimod-induced skin inflammation by regulating IL-23 receptor expression

The anti-inflammatory effect of omega 3 polyunsaturated fatty acids has been confirmed in various inflammatory disease models. Maresin-1 (MaR1) is a lipid mediator derived from the omega-3 fatty acid docosahexaenoic acid (DHA) that has displayed strong anti-inflammatory effects in various inflammatory disease models. However, the effect of topical MaR1 on cutaneous inflammation remains unclear. Therefore, we initially examined the anti-inflammatory effects of topical Maresin-1 using an imiquimod (IMQ)-induced psoriasis-like mouse model of inflammation. Topical MaR1 reduced the ear swelling response as seen in histological findings. RT-PCR and flow cytometry analyses revealed MaR1 had no inhibitory effect on IL-23, but MaR1 suppressed IL-17A production by γδTCR^mid+ and CD4⁺ cells in the skin. These inhibitory effects were also observed in a subcutaneous IL-23-injected psoriasis model. MaR1 downmodulated IL-23 receptor (IL-23R) expression by suppressing retinoic acid-related orphan receptor γt (RORγt) expression and internalization in a clathrin-dependent manner in γδTCR^mid+ and CD4⁺ cells. These results lead to assumptions that topical MaR1 may be a new therapeutic agent for psoriasis and other IL-17-mediated cutaneous inflammatory diseases.

The severity of imiquimod-induced mouse skin inflammation is independent of endogenous IL-38 expression

The IL-1 cytokine family includes eleven members, among which Il-36α, β and γ, IL-36Ra and IL-38. The IL-36 cytokines are involved in the pathogenesis of psoriasis. IL-38 is also expressed in the skin and was previously proposed to act as an IL-36 antagonist. In this study, we thus examined expression and function of Il-38 in a mouse model of imiquimod (IMQ)-induced skin inflammation. Il-38 mRNA was detected in the epidermis and in primary mouse keratinocytes, but not in dermal fibroblasts. At the peak of IMQ-induced inflammation, skin Il-38 mRNA levels were reduced, whereas Il-36ra mRNA expression increased. The severity of IMQ-induced skin inflammation, as assessed by recording ear thickness and histological changes, was similar in Il-38 KO and WT littermate control mice, while, in contrast, Il-36ra-deficient mice displayed more severe skin pathology than their WT littermates. Il-38-deficiency had no impact on IMQ-induced expression of proinflammatory mediators in the skin in vivo, on the basal expression of various cytokines or chemokines by cultured primary keratinocytes and dermal fibroblasts in vitro, or on the response of these cells to Il-36β. Finally, after cessation of topical IMQ application, the resolution of skin inflammation was also not altered in Il-38 KO mice. In conclusion, Il-38-deficiency did not impact the development or resolution of IMQ-induced skin inflammation. Our observations further suggest that endogenous Il-38 does not exert Il-36 inhibitory activity in this model, or in cultured skin cells. A potential anti-inflammatory function of Il-38 in mouse skin thus still remains to be demonstrated.

Effect of γ-secretase inhibitor on Th17 cell differentiation and function of mouse psoriasis-like skin inflammation

Background

Th17 cells and its effective cytokine IL-17A play an important role in the pathogenesis of abnormal immune responses in psoriasis. Notch1 signaling has been implicated in Th17 cell differentiation and function. In this study, our aim was to evaluate the possible inhibitory effect of Notch1 signaling inhibitor, γ-secretase inhibitor DAPT, on psoriatic Th17 cell differentiation and function in a mouse model of psoriasis-like skin inflammation.

Methods

Mouse psoriasis-like skin inflammation model was established by topical 5% imiquimod (IMQ) application, and experimental mice were divided into control group, IMQ-treated group and IM + DAPT-treated group. DAPT and the equivalent amount of Dimethyl sulfoxide was intraperitoneally injected in IMQ + DAPT-treated group and the other two experimental groups respectively. Skin tissues of the three experimental groups were acquired and stained with haematoxylin and eosin (HE). Splenic single-cells and serum were collected to detect the percentage of Th17 cells, the mRNA expression levels of Notch1 and its target gene Hes-1, Th17-specific transcription factor RORγt and its effective cytokines IL-17A, as well as IL-17A serum concentration. In addition, splenic CD4⁺ T cells from IMQ-treated mice were isolated and treated by DAPT to further measure the inhibitory effect of DAPT on the Th17 cell differentiation and IL-17A secretion in vitro.

Results

DAPT treatment alleviated the severity of IMQ-induced mouse psoriasis-like skin inflammation and decreased the scores of erythema, scaling and thickening. HE stain reveals obviously reduced epidermal hyperplasia and dermal inflammatory cells infiltration in IMQ + DAPT-treated mice. The increased expression of splenic Th17 cell percentage, along with Notch1, Hes-1, RORγt and IL-17A mRNA and IL-17A serum concentration in IMQ-treated mice were significantly decreased when experimental mice were treated by IMQ and DAPT combinedly. Data obtained from in vitro study in IMQ-treated mice also demonstrated that blocking Notch1 signaling by DAPT can result in a dose-dependent decrease of Th17 cell proportion, mRNA expression of Notch1, Hes-1, RORγt and IL-17A as well as IL-17A secretion in splenic CD4⁺ T cells.

Conclusion

These data suggest that Notch1 inhibition by DAPT can effectively alleviate the severity of mouse psoriasis-like skin inflammation by regulating the differentiation and function of Th17 cells, indicating that DAPT might be a potential therapeutic candidate for the treatment of psoriatic inflammation.

Suppressing IL-36-driven inflammation using peptide pseudosubstrates for neutrophil proteases

Sterile inflammation is initiated by molecules released from necrotic cells, called damage-associated molecular patterns (DAMPs). Members of the extended IL-1 cytokine family are important DAMPs, are typically only released through necrosis, and require limited proteolytic processing for activation. The IL-1 family cytokines, IL-36α, IL-36β, and IL-36γ, are expressed as inactive precursors and have been implicated as key initiators of psoriatic-type skin inflammation. We have recently found that IL-36 family cytokines are proteolytically processed and activated by the neutrophil granule-derived proteases, elastase, and cathepsin G. Inhibitors of IL-36 processing may therefore have utility as anti-inflammatory agents through suppressing activation of the latter cytokines. We have identified peptide-based pseudosubstrates for cathepsin G and elastase, based on optimal substrate cleavage motifs, which can antagonize activation of all three IL-36 family cytokines by the latter proteases. Human psoriatic skin plaques displayed elevated IL-36β processing activity that could be antagonized by peptide pseudosubstrates specific for cathepsin G. Thus, antagonists of neutrophil-derived proteases may have therapeutic potential for blocking activation of IL-36 family cytokines in inflammatory conditions such as psoriasis.

Oral Administration of Vanillin Improves Imiquimod-Induced Psoriatic Skin Inflammation in Mice

Vanillin is one of the most widely used flavoring products worldwide. Psoriasis is a chronic inflammatory skin disorder. The interleukin-23 (IL-23)/interleukin-17 (IL-17) axis plays a critical role in psoriasis. Here, we analyzed the effect of vanillin on imiquimod (IMQ)-induced psoriatic skin inflammation in mice. Mice were treated topically with IMQ on the back skin and orally with various amounts of vanillin for 7 consecutive days. Vanillin significantly improved IMQ-induced histopathological changes of skin in a dose-dependent manner. The thickness and number of cell layers of epidermis were reduced by 29 ± 14.4 and 27.8 ± 11%, respectively, in mice given 100 mg/kg of vanillin. A microarray showed that a total of 9042 IMQ-upregulated genes were downregulated by vanillin, and the biological pathways involved in the immune system and metabolism were significantly altered by vanillin. The upregulated expressions of IL-23, IL-17A, and IL-17F genes were suppressed by vanillin, with fold changes of -3.07 ± 0.08, -2.06 ± 0.21, and -1.62 ± 0.21, respectively. Moreover, vanillin significantly decreased both the amounts of IL-17A and IL-23 and the infiltration of immune cells in the skin tissues of IMQ-treated mice. In conclusion, our findings suggested that vanillin was an effective bioactive compound against psoriatic skin inflammation. Moreover, the downregulation of IL-23 and IL-17 expression suggested that vanillin was a novel regulator of the IL-23/IL-17 axis.

Topical administration of reversible SAHH inhibitor ameliorates imiquimod-induced psoriasis-like skin lesions in mice via suppression of TNF-α/IFN-γ-induced inflammatory response in keratinocytes and T cell-derived IL-17

DZ2002, a reversible S-adenosyl-l-homocysteine hydrolase (SAHH) inhibitor with immunosuppressive properties and potent therapeutic activity against various autoimmune diseases in mice. The present study was designed to characterize the potential therapeutic effects of DZ2002 on murine model of psoriasis and reveal the correlated mechanisms. In this report, we demonstrated that in vitro, DZ2002 significantly decreased the expression of pro-inflammatory cytokines and adhesion molecule including IL-1α, IL-1β, IL-6, IL-8, TNF-α and ICAM-1 by inhibiting the phosphorylation of p38 MAPK, ERK and JNK in TNF-α/IFN-γ-stimulated HaCaT human keratinocytes. Topical administration of DZ2002 alleviated the imiquimod (IMQ)-induced psoriasis-like skin lesions and inflammation in mice, the therapeutic effect was comparable with the Calcipotriol. Moreover, the inflammatory skin disorder was restored by DZ2002 treatment characterized by reducing both of the CD3⁺ T cell accumulation and the psoriasis-specific cytokines expression. Further, we found that DZ2002 improved IMQ-induced splenomegaly and decreased the frequency of splenic IL-17-producing T cells. Our finding offered the convincing evidence that SAHH inhibitor DZ2002 might attenuate psoriasis by simultaneously interfering the abnormal activation and differentiation of keratinocytes and accumulation of IL-17-producing T cells in skin lesions.

Resolvin D1 attenuates imiquimod-induced mice psoriasiform dermatitis through MAPKs and NF-κB pathways

BACKGROUND

Resolvin D1 (RvD1), a pro-resolution lipid mediator derived from docosahexaenoic acid (DHA), has been described to promote several kinds of inflammatory resolution. However, the effects and anti-inflammatory mechanisms of RvD1 on psoriasis have not been previously reported.

OBJECTIVE

The present study aimed to determine the protective effects and the underlying mechanisms of RvD1 on imiquimod (IMQ)-induced psoriasiform dermatitis.

METHODS

Mice were topically treated with IMQ to develop psoriasiform dermatitis on their shaved back, pretreated intraperitoneally (i.p.) with or without RvD1 or tert-butoxycarbonyl Met-Leu-Phe peptide (Boc), a lipoxin A4 (ALX) receptor antagonist. The severity was monitored and graded using a modified human scoring system, the Psoriasis Area and Severity Index (PASI), histopathology, and the signature cytokines of psoriasis (IL-23, IL-17, IL-22 and TNF-α). The mRNA and protein levels of inflammatory cytokines were quantified by quantitative real-time PCR (QRT-PCR) and ELISA. The expressions of signaling proteins MAPKs and NF-κB p65 were analyzed using western blotting. Electrophoretic mobility shift assay (EMSA) was used to check NF-κB p65 DNA binding activity.

RESULTS

Our study showed that RvD1 alleviated IMQ-induced psoriasiform dermatitis and improved skin pathological changes. RvD1 markedly inhibited IMQ-induced activation of ERK1/2, p38, JNK (c-Jun N-terminal protein kinase, a subfamily of MAPKs), and NF-κB. Furthermore, pretreatment with Boc, would not exacerbate skin inflammation of IMQ-induced mice, but significantly reversed the beneficial effects of RvD1 on IMQ-induced psoriasiform inflammation.

CONCLUSION

RvD1 can obviously improve skin inflammation in IMQ-induced mice psoriasiform dermatitis. The protective mechanisms might be related to its selective reaction with lipoxin A4 receptor/Formyl-peptide receptor 2 (ALX/FPR2), by downregulating relevant cytokines of the IL-23/IL-17 axis expression, the inhibition of MAPKs and NF-κB signaling transduction pathways. Thus, these results show that RvD1 could be a possible candidate for psoriasis therapy.