Advanced Characterization of Imiquimod-Induced Psoriasis-Like Mouse Model

Nitazoxanide and Umbelliferone improves Imiquimod-induced psoriasis in Balb/C mice

Signal Transducer and Activator of Transcription (STAT) 3 is a significant contributor to the development and pathogenesis of psoriasis (Pso). Research demonstrated STAT3 signalling to be upregulated in Pso. Additionally, Pso results in oxidative stress that activates various signalling pathways like factor nuclear kappa-B (NF-κB). Nitazoxanide (NTZ) is an antiprotozoal drug shown to inhibit the STAT3 pathway. Umbelliferone (UMB) is an antioxidant, and anti-inflammatory and can suppress NF-κB signalling. Therefore, we propose to hypothesize that NTZ and UMB would be effective in treating Pso. Balb/c mice were treated with IMQ to induce Pso. The clinical characteristics of Pso were assessed using the Psoriasis Area and Severity Index (PASI), back skin thickness, spleen length and mass, and histology of the skin sample tissue. In addition, we measured the levels of interleukin-17 (IL-17), tumor necrosis factor-α (TNF-α), STAT3, and NF-κB. Furthermore, to gain the interaction of NTZ and UMB with STAT3, a detailed in-silico study has been performed. The impact of treatment on oxidative stress was evaluated by estimating the activity of superoxide dismutase (SOD) and catalase (CAT). The results demonstrate that mice subjected to IMQ-induced Pso exhibited positive responses to treatment with NTZ and UMB. Additionally, IL-17, TNF-α levels, STAT3, and NF-κB were decreased in NTZ and UMB-treated groups. SOD and CAT levels in NTZ and UMB groups were elevated. Our findings show that NTZ and UMB are potential therapeutic medications for Pso.

Costus speciosus extract: a natural immunomodulator for treatment of psoriasis in BALB/c mice by NF-κB pathway

Psoriasis is a chronic inflammatory skin condition. Ayurveda, Traditional Chinese therapy, and Unani offer a potential approach to treating psoriasis. This study explores the immunomodulatory effects of Costus speciosus petroleum ether extract (CSPE) on psoriasis-like symptoms in Balb/c mice. GC-MS analysis was done to detect bioactive phytoconstituents in the extract. Mice were treated with Imiquimod (IMQ) to induce psoriasis-like symptoms. Measurements of back skin thickness, skin length, mass, and body weight were used in the study, with an assessment of the Psoriasis Area and Severity Index (PASI). The treatment group received doses of 110 mg/kg, 220 mg/kg, and 440 mg/kg of extracts. Nuclear Factor kappa-B (NF-kB), tumor necrosis factor-alpha (TNF-α), and interleukin-17 (IL-17) were estimated. Presence of diosgenin, tigogenin, aglycone of diosgenin, santamarine and reynosin in the extract was confirmed by GC-MS analysis. At 440 mg/kg, a significant effect was observed in the IMQ model. The extract significantly reduced levels of NF-kB, TNF-α, and IL-17. The research findings indicate that CSPE is a promising candidate for psoriasis treatment.

Intradermal delivery of teriflunomide loaded emulsomes using hollow microneedles for effective minimally invasive psoriasis management

Conventional topical psoriasis treatments suffer from limited delivery to affected areas along with skin irritation due to high local drug concentration. Herein an attempt to improve the delivery of leflunomide's active metabolite (teriflunomide (TER)) by improving its solubility through nanoencapsulation in emulsomes (EMLs) besides ensuring effective intradermal delivery using hollow microneedles. Evaluation of colloidal characteristics of EMLs, encapsulation efficiency and drug release were performed. Additionally, the antipsoriatic activity in an imiquimod-induced psoriatic mouse model was evaluated by the measurement of inflammatory mediators' levels and histopathological assessment of anatomized skin. The particle size of the chosen EMLs formulation was 147.9 nm and the zeta potential value was -21.7. Entrapment efficiency was 97.23 % and EMLs provided sustained drug release for 48 h. No statistically significant differences in the in vivo levels of NF-KB, IL 8, MMP1, GSH, SOD and catalase between the animals treated by TER-EMLs and the negative control cohort were observed. Also, histopathological inspection of dissected skin samples reflected the superiority of TER-EMLs over TER suspension. Collectively, combining nanoencapsulation and hollow microneedles application improved TER properties and ensured effective TER delivery to the affected psoriatic areas.

Vildagliptin topical ointment: an effective treatment for imiquimod-induced psoriasis in mice

Psoriasis is a chronic immune-related dermatosis characterized by inflamed, thickened, brownish-red, peeling skin patches. Vildagliptin is an anti-diabetic drug with novel anti-inflammatory, anti-oxidative, and anti-proliferative activities. This study aimed to assess the anti-psoriatic activity of topical vildagliptin. 40 Swiss albino mice were sorted into five groups, each with 8 animals. The control group obtained no treatment. The induction group obtained imiquimod cream (5%) at a dose of 62.5 mg per day. The vehicle group obtained imiquimod (as did the induction group), accompanied by topical vehicle application. The clobetasol group obtained imiquimod cream (as did the induction group), and two hours later, clobetasol ointment (0.05%) was administered. The vildagliptin group obtained imiquimod (as in the induction group), followed by topical vildagliptin ointment (3%), two hours after induction. The experiment lasts for 8 consecutive days. Evaluations were conducted on the results of biochemical indicators, histological assessments, and clinical observations. Vildagliptin administered topically effectively corrected psoriatic histological irregularities, improved the psoriasis-like skin lesions such as erythema, flacking, and acanthosis, and attenuated the imiquimod-provoked elevations of PASI and Baker's score. Further, overexpression of inflammatory markers (TNF-α, IL-17 A, IL-23, and IL-22), angiogenic markers (VEGF), oxidative-stress components (MDA and SOD), and proliferative factors (Ki-67) were dramatically mitigated by vildagliptin treatment. Topical vildagliptin has profound anti-psoriatic effects.

Integration of Synchronizing In Silico, In Vitro, and In Vivo Strategies for the Development of Antipsoriatic Apremilast-loaded Nanostructured Lipid Carrier Embedded in Hydrogel

One of the major challenges in the psoriasis therapies is the systemic side effects. This research investigation intended to design, formulate, and characterize topical Apremilast (APR) nanostructured lipid carriers (NLCs) embedded hydrogel. APR-loaded NLCs were prepared using the hot melt ultrasonication technique using glyceryl monostearate (GMS) and Capmul® MCM, followed by high-speed homogenization. The entrapment and size were 85.5 ± 2.1% and 242.5 ± 3.1 nm, respectively. Using molecular docking, the interactions between APR-GMS and APR-Capmul® MCM were investigated. 32 factorial designs were used to optimize APR-loaded NLCs, employing a quality-by-design approach. The spherical shape of the nanocarriers was depicted in the SEM images of NLCs dispersion. With a regression value of 0.9745, the in vitro drug release of APR-NLCs dispersion matched the Higuchi model and demonstrated extended-release up to 28 hrs (99.0 ± 1.7%). An in vitro cellular toxicity depicted that formulation excipients had minimal effect, as cell viability was still > 80% at concentrations of up to 30 µg/mL. APR-NLC hydrogel exhibited extended release up to 36 hrs (97.1 ± 0.8%), with diffusion as a release mechanism. Since there was no significant difference observed in viscosity (cp) or % CDR throughout 24 hrs at 5°, indicate APR-NLCs hydrogel was stable in a refrigerated condition. Compared to the positive control, APR liquid, and pure drug, APR-NLCs hydrogel showed a substantial decrease in PASI score. Topical APR-loaded NLCs embedded in Hydrogel enhanced efficacy in the imiquimod-induced psoriasis in the murine model found to be non-irritating with minimal systemic side effects. The findings imply that APR-loaded NLCs embedded in Hydrogel can be used topically to treat psoriasis by focusing on the skin's outer layers.

Cell type-specific enhancers regulate IL-22 expression in innate and adaptive lymphoid cells

IL-22, a signature cytokine of type 3 lymphoid cells, mediates epithelial homeostasis and protective pathogen responses in barrier tissues, while its deregulated expression drives chronic inflammation associated with colitis and psoriasis. Despite its therapeutic value, little is known about regulatory elements for IL-22 expression. We identify two conserved enhancers, E22-1 and E22-2, which differentially regulate Il22 in type 3 lymphoid subsets. These enhancers are required for steady-state expression of gut antimicrobial peptides, protection from C. rodentium infection, and development of IL-22-mediated psoriasis. E22-1 resembles many known enhancers, functioning in both Th-ILC counterparts. However, E22-2 is only required for IL-22 expression in ILC3s. Its ILC3 restriction relies on multiple Runx3 sites, combined with the lack of a functional RORγt motif, which is present in E22-1. Thus, although responding to similar stimuli, type 3 lymphoid cells use distinct cis-elements for IL-22 expression, with E22-2 likely serving as a homeostatic enhancer in barrier tissues.

Curcumol attenuates hyperproliferation and inflammatory response in a psoriatic HaCaT keratinocyte model by inhibiting the PI3K-Akt pathway and ameliorates skin lesions and inflammatory status in psoriasis-like mice

Psoriasis, a chronic autoimmune disorder, is characterized by keratinocyte hyperproliferation and inflammatory responses. Curcumol, a bioactive terpenoid, possesses antiproliferative and anti-inflammatory properties. This study evaluates the efficacy of curcumol in treating psoriasis in both in vitro and in vivo models. In vitro, curcumol inhibits hyperproliferation and inflammatory responses in a psoriatic HaCaT keratinocyte model stimulated by M5 cytokines by inhibiting the PI3K-Akt pathway. Additionally, in vivo, curcumol ameliorates psoriasis-like skin lesions and inflammatory status in imiquimod-induced mice. Network pharmacology revealed that curcumol's beneficial effects might involve the PI3K-Akt signaling pathway. Further investigation shows that curcumol partially counteracts the activation of PI3K-Akt by recilisib in keratinocytes. These results suggest that curcumol may be a promising therapeutic option for psoriasis.

Birinapant improves imiquimod-induced psoriasis in BALB/c mice

OBJECTIVES

This study investigates the effects of birinapant, a novel compound, on psoriasis-like symptoms induced by imiquimod in Balb/c mice.

MATERIAL AND METHODS

Male Balb/c mice were treated with imiquimod (IMQ) to induce psoriasis-like symptoms. The clinical characteristics of psoriasis were assessed using the Psoriasis Area and Severity Index, as well as back skin thickness, skin length and mass, and body weight alterations. The treatment groups included those receiving birinapant, with the assessment on the levels of interleukin-17 and tumor necrosis factor -α, two key cytokines involved in the inflammatory process of psoriasis. The study found that birinapant significantly reduced the levels of these cytokines, providing reassurance about its potential to combat psoriasis. Additionally, the study evaluated the effect of birinapant on oxidative stress levels to determine its role in maintaining skin homeostasis.

RESULT AND DISCUSSION

The findings from this study revealed that mice subjected to IMQ-induced psoriasis exhibited positive responses to 21 days of treatment with birinapant (50 mg/kg). The levels of interleukin-17 and tumor necrosis factor-alpha, in the skin of IMQ-treated mice significantly decreased, indicating its effectiveness in reducing inflammation associated with psoriasis. Furthermore, Birinapant positively affected oxidative stress maintenance, suggesting its potential role in promoting skin health and homeostasis.

CONCLUSION

By demonstrating birinapant's efficacy, this research paves the way for further studies that could lead to the development of more effective therapies for psoriasis.

Topical delivery of pterostilbene nanoemulgel ameliorates imiquimod-induced psoriasis-like skin inflammation in mice

AIM

This study evaluates the therapeutic potential of Pterostilbene (PTN), a natural stilbenoid, in an imiquimod (IMQ)-induced psoriasis model. Due to PTN's poor solubility and bioavailability, a pterostilbene nano-emulsion gel (PTN-NEG) formulation (0.1% and 0.2% w/w) was developed to enhance its therapeutic efficacy.

METHODS

Psoriasis was induced in C57BL/6J mice by applying IMQ (62.5 mg/day) on a 5 cm2 shaved dorsal skin area for 7 days. PTN-NEG was topically applied, and its effects on oxidative stress, inflammatory cytokines (IL-17, TNF-α, IL-22), NF-κB pathway activation, and keratinocyte proliferation markers (Ki-67, Bcl-xL) were assessed. The expression of dual-specificity phosphatase-1 (DUSP-1) and its role in modulating mitogen-activated protein kinase (MAPK) signaling were evaluated. Additionally, DNA methyltransferase-1 (DNMT-1) inhibition was examined to explore PTN's epigenetic impact.

RESULTS

PTN-NEG restored antioxidant balance, reduced pro-inflammatory cytokines, inhibited NF-κB activation, and suppressed keratinocyte proliferation. It unregulated DUSP-1, modulating MAPK signaling and preventing psoriasis progression. PTN-NEG also improved epidermal structure, reduced hyperplasia, and prevented splenomegaly. Notably, PTN inhibited DNMT-1, suggesting a novel epigenetic mechanism for psoriasis.

CONCLUSION

To our knowledge, this study is the first to demonstrate that PTN-NEG mitigates psoriasis through anti-inflammatory, antioxidant, and epigenetic regulatory mechanisms, highlighting its therapeutic potential in psoriasis management.

Co-Delivery of Tacrolimus and Thymoquinone Topically by Nanostructured Lipid Carrier Gel for Enhanced Efficacy Against Psoriasis

Psoriasis is a chronic inflammatory skin disorder affecting 2-5% of the global population and is often characterized by skin thickening, scaling, and various epidermal changes. Current topical treatments have limitations in terms of efficacy, skin penetration, and side effects. The present study aimed to develop a novel nanostructured lipid carrier (NLC) gel that co-encapsulates tacrolimus (TAC) and thymoquinone (THQ) to enhance drug delivery and efficacy in the treatment of psoriasis. TAC-THQ-NLC was formulated using the emulsification solvent-evaporation technique and subsequently converted into nanogel using Carbopol Ultrez10 as a gelling agent. The prepared nanogel efficacy was evaluated through ex-vivo skin permeation, dermatokinetic analysis, and psoriasis-induced Balb/c mice model. The TAC-THQ-NLC-gel (TAC-THQ-NG) demonstrated significantly higher skin permeation compared to the TAC-THQ-suspension-gel (TAC-THQ-SG). Specifically, the permeation enhancement for the NLC-gel was 2.51-fold and 2.12-fold for TAC and THQ, respectively. These enhancements were confirmed using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The dermatokinetic analysis showed that the TAC-THQ-NG had 2.78-fold and 2.37-fold higher maximum concentration (Cmax) and 2.93-fold and 2.40-fold higher area under the curve (AUC) for TAC and THQ, respectively, compared to the TAC-THQ-SG. Further, in the Balb/c mice psoriasis model, the TAC-THQ-NG formulation resulted in an 83.80 ± 3.62% reduction in the cumulative Psoriasis Area Severity Index (PASI) score of thickness, erythema, and scaling, compared to the TAC-THQ-SG formulation, which showed 57 ± 9.90% reduction. The results of the in vivo skin compliance study suggested that the developed TAC-THQ-NG was safe for topical application. Further histopathological examination showed no significant changes in the skin, spleen, and liver, indicating the efficacy and safety of the TAC-THQ-NG formulation. Based on these observations, it can be inferred that the developed TAC-THQ-NG exhibits superior therapeutic efficacy.

Probing the dark chemical matter against PDE4 for the management of psoriasis using in silico, in vitro and in vivo approach

The potential downsides for the present treatment for psoriasis are drug resistance, reduced efficacy, risk of mental episodes, and drug interactions. Hence, this study aims to discover a new drug for psoriasis by considering global research efforts and exploring underrepresented chemical space regions. The objective was to identify novel PDE4D inhibitors from the dark chemical matter (DCM) database for treating psoriasis. To address this we have coupled molecular docking and pharmacophore screening with molecular dynamics (MD) to identify hit molecules. Additionally, pharmacokinetics optimization was performed using machine learning and artificial intelligence which are key parts of drug discovery and development processes. The 139,353 DCM molecules were evaluated for their binding mode and interaction with critical residues such as GLN369, ILE336, PHE340, and PHE372 of the phosphodiesterase-4D (PDE4D) enzyme. Here, 15 hits were obtained through successive virtual screening procedures and all the 15 molecules were subjected to MD simulations for hit identification. In the MD studies, a stable root mean square deviation (RMSD) and ligand-protein interactions were found with four molecules, namely 027230, 060628, 060576, and 085881. The ligand 085881 was found promising because it inhibits LPS-induced IL-6 and TNF-alpha secretion from THP-1 cells with IC50 of 18.41 μM and 34.43 μM, respectively. In vivo erythema grading showed that 085881 possesses mild to moderate anti-psoriatic action. This study demonstrates the effective use of computational techniques to discover novel PDE4D inhibitors and provides insight into their therapeutic potential for treating inflammatory diseases such as psoriasis.

Transcutaneous delivery of disease-specific PI3K/Akt/mTOR inhibitor-based hybrid nanoparticles in hydrogel system for the management of psoriasis: Insights from in vivo studies

Psoriasis is a chronic autoimmune skin disorder characterized by excessive epidermis thickening, keratinocyte proliferation, and angiogenesis, driven by the PI3K/Akt/mTORC1, one of the key signalling axis of psoriasis. Corticosteroids used for treatment have limited efficacy and numerous side effects, thereby necessitating the development of safer, targeted therapeutic options for improved disease management and patient outcomes. Here we address this problem by encapsulating the PI3K/Akt/mTORC1 inhibitor Rapamycin in lipid-polymeric conjugated hybrid nanoparticles (RPMN) and incorporating these particles in a carbopol-based hydrogel system (RPMNGel), with enhanced release kinetics, long-term stability, better spreadability over reported literature for the treatment of psoriasis, and skin residence time. Using an in-vivo imiquimod-induced psoriatic model, in comparison to free drug-loaded gels, RPMNGel showed increased accumulation and deeper epidermal penetration, and slower diffusion within the psoriatic skin without causing any side effects to normal skin. The cumulative psoriasis area severity index score reduced from 10.5 to 5. 1 at day 7 in the group treated with RPMNGel. Overall, our studies establish the efficacy of RPMNGel for improved psoriasis treatment and management through enhanced drug penetration, prolonged drug release and reduced systemic toxicity.

Antibacterial Chitosan-Based Double-Network Hydrogel Patch Loaded with Antioxidant Ceria Nanoparticles and Betamethasone to Treat Psoriasis

Psoriasis is a chronic inflammatory skin disorder characterized by keratinocyte hyperproliferation, oxidative stress, and immune dysregulation. In this study, we developed a multifunctional, double-network hydrogel, composed of chitosan and poly(acrylic acid), embedded with cerium oxide nanoparticles (CeNPs) and betamethasone. The hydrogel harnesses the redox-catalytic properties of CeNPs to scavenge reactive oxygen species (ROS) while ensuring sustained betamethasone release for antibacterial and anti-inflammatory effects. Its mechanical stability and high water retention make it suitable for long-term skin application. In vitro, the hydrogel enhanced keratinocyte viability under oxidative stress and showed significant antibacterial activity against Escherichia coli. In a psoriasis-induced mouse model, the hydrogel significantly reduced epidermal hyperplasia, suppressed keratinocyte proliferation, and lowered inflammatory cytokine levels. The combination of antioxidant, antibacterial, and anti-inflammatory properties suggests that this hydrogel offers a promising therapeutic strategy for psoriasis, addressing both oxidative stress and inflammation for effective treatment.

The alleviative effects of canagliflozin on imiquimod-induced mouse model of psoriasis-like inflammation

Psoriasis is a life-long immune-mediated dermatosis with thickened, reddish, and flaky skin patches. Canagliflozin is a gliflozin antidiabetic with non-classical remarkable antioxidative, anti-inflammatory, anti-proliferative, and immune-modulating effects. The aim of this study is to examine the probable effects of topical canagliflozin on a mouse model of imiquimod-provoked psoriasis-like dermatitis. The study evaluated 20 Swiss white mice, sorted haphazardly into 4 groups of 5 animals each. Every mouse, with the exception of the control group, had imiquimod applied topically to their shaved backs for 7 days. The control group included healthy mice that were not given any treatment. Mice in the other three groups underwent topical treatment with vehicle (induction group), 0.05% clobetasol propionate ointment (clobetasol group), or 4% canagliflozin emulgel (canagliflozin 4% group) on exactly the same day as imiquimod cream was administered. Topical canagliflozin markedly lowered the intensity of imiquimod-provoked psoriasis eruptions, featuring redness, glossy-white scales, and acanthosis, while also correcting histopathological aberrations. Canagliflozin administration to imiquimod-exposed animals resulted in significantly decreased cutaneous concentrations of inflammatory mediators such as IL-8, IL-17, IL-23, and TNF-α, with raised levels of IL-10. Canagliflozin further lowered proliferative factors involving Ki-67 and PCNA, diminished oxidative indicators such as MDA and MPO, and augmented the activity of antioxidant markers, notably SOD and CAT. Canagliflozin might alleviate the imiquimod-induced animal model of psoriasis, probably thanks to its profound anti-inflammatory, antioxidant, antiangiogenic, and antiproliferative activities.

Hyaluronic acid modified liposomes with enhanced transdermal delivery of methotrexate for psoriasis treatment

Psoriasis is a chronic inflammatory skin disorder characterized by immune dysregulation and cutaneous symptoms. Methotrexate (MTX), efficacious in psoriasis, suffers from limited transdermal permeability due to its hydrophilic nature. Liposomal nanomedicine, which offers increased bioavailability and targeted delivery with minimized systemic effects, is a promising approach. The application of hyaluronic acid (HA) as a penetration enhancer and modifier leverages its binding to the upregulated CD44 receptor in psoriasis, enhancing the efficacy of liposomes. In this study, we synthesized HA-modified liposomes by conjugating HA with distearoyl phosphatidyl ethanolamine-poly (ethylene glycol) (DSPE-PEG) and encapsulated methotrexate for targeted treatment of psoriasis. The research entailed the meticulous preparation and physicochemical characterization of these HA-modified liposomes, followed by in vitro transdermal delivery assays, cellular uptake studies, and the development of a psoriasis animal model to rigorously assess therapeutic efficacy. Our findings underscore the significant improvement in methotrexate's transdermal penetration and retention within psoriatic lesions afforded by the HA-modified liposomes, indicating a novel and efficacious therapeutic approach for the management of dermatological disorders.

Topical delivery of siRNA to psoriatic skin model using high molecular weight chitosan derivatives: In vitro and in vivo studies

Psoriasis is a chronic inflammatory skin disease that, like other immune-mediated conditions, may benefit from small interfering RNA (siRNA)-based therapies, which are emerging as a promising alternative by addressing several limitations of current treatments. In this study, topical formulations of chitosan-based vectors were developed to deliver siRNA targeting tumor necrosis factor alpha (TNFα) to inflamed skin. Grafting diisopropylethylamine (DIPEA) and polyethylene glycol (PEG) onto the chitosan backbone enhanced siRNA delivery efficiency under physiological conditions, forming robust polymeric vectors with high structural and colloidal stability. These vectors provided siRNA protection against RNAse degradation and oxidative damage. Additionally, the chitosan derivatives displayed lysozyme-mediated biodegradability comparable to native chitosan, while PEG was released in response to reductive environments, supporting controlled vector disassembly. The PEGylated DIPEA-chitosan/siRNA polyplexes demonstrated positive zeta potentials (up to + 11 mV), particle sizes of 100-200 nm, and very low cytotoxicity in keratinocyte and fibroblast cell lines. In vitro, the polyplexes achieved TNFα knockdown levels (65%) in RAW macrophages, comparable to those obtained with Lipofectamine™. Topical formulations showed enhanced interaction of vectors with skin models (Strat-M® and porcine ear skin) compared to naked siRNA. Furthermore, in vivo studies indicated that hair follicles were a key route for polyplexes to penetrate deeper skin layers. A rodent model of psoriasis induced by imiquimod was treated topically with these vectors, resulting in approximately a 50% reduction in TNFα levels at inflammation sites, decreased immune cell infiltration, and preservation of epidermal structure. These findings collectively underscore the potential of DIPEA-chitosan-based vectors for topical siRNA-based therapies.

Effects of topical isoxsuprine ointment on imiquimod-induced psoriasiform skin inflammation in mice

This study assesses the potential positive impact of a 0.05% isoxsuprine ointment on psoriasiform skin inflammation generated by imiquimod in mouse models. Thirty-two male albino mice were allocated into four groups: the control group (which received topical emollients twice daily for 16 days), the induction group (which received imiquimod cream (5%) for 8 days, twice daily followed by petrolatum gel (15%) for another 8 days), and the other two groups, which received imiquimod cream (5%) for 8 days followed by either clobetasol ointment (0.05%) or isoxsuprine ointment (0.05%) twice daily for an additional 8 days. At the end of the experiment, mice were sacrificed by ethical standards, and levels of TNF-α, IL-6, IL-17A, IL-23, and VEGF were measured; PASI and Backer's score were examined, in addition to the histopathology of skin tissue. Each clobetasol and isoxsuprine group displayed a significant reduction in tissue homogenate levels of TNF-α, IL-6, IL-17A, IL-23, and VEGF, besides increments in IL-10 compared to the induction group. Some markers (IL-17A, IL23, and VEGF) showed no significant difference between clobetasol and the isoxsuprine group. In contrast, the other markers (TNF-α, IL6, and IL10) showed significant differences between clobetasol and isoxsuprine groups. Isoxsuprine ointment showed comparable efficacy to clobetasol ointment in treating imiquimod-induced psoriasiform skin inflammation in mice models, probably due to its possible effect of anti-inflammatory and immunomodulatory activities.

Rational design and therapeutic potential of MyD88 inhibitory peptide in psoriasis

Myeloid differentiation primary-response 88 (MyD88) is a crucial adaptor protein for initiating immune responses via Toll-like receptors (TLRs). This study employed a rational peptide design approach to develop MyD88 inhibitory peptides targeting the MyD88 interaction interface. The designed peptide, MyDIP2-4, was evaluated for its efficacy in inhibiting MyD88-dependent signaling in human and mouse cell lines. In vitro analyses demonstrated that MyDIP2-4 effectively inhibited MyD88-mediated signaling in both the TLR- and IL-1R-mediated pathways. Surface plasmon resonance experiments confirmed that MyDIP2-4 specifically interacted with MyD88 in a concentration-dependent manner. In an imiquimod-induced psoriasis model, MyDIP2-4 significantly inhibited disease progression, as evidenced by a reduction in psoriasis area and severity index scores. Histological staining revealed decreased epidermal thickness, while immunohistochemical analysis showed downregulation of IL-17 levels following treatment. These findings suggest that MyDIP2-4 is a promising candidate for the treatment of psoriasis. Targeting the Toll/interleukin-1 receptor domain of MyD88 through rational peptide design offers a novel strategy for developing therapeutics for autoimmune diseases.

Ivermectin decreases inflammation and imiquimod-induced psoriasis-like skin lesions in rat via targeting TLR4/p65 NF-κB

Objectives

Psoriasis is a chronic skin disease that usually manifests as white and silver spots on the skin. Because of its anti-inflammatory properties, we investigated the effects of ivermectin (IVM) on imiquimod (IMQ)-induced psoriasis in rats.

Materials and Methods

Fifteen rats were assigned to 3 different groups (n=5 per group): the control group received normal water and food; the psoriasis group, in which psoriasis was induced by topical application of IMQ (1 mg per rat), and treatment group where rats were treated daily with topical IVM-gel (1%) from day 3 to 7. The Psoriasis Area Severity Index (PASI) Score for the entire treatment period was used to assess erythema, silver scale, and skin thickness on the dorsal region of rats, and the spleen-to-body weight index on day 7 was examined. Moreover, histological assessment of skin tissues was performed using fluorescence immunostaining and hematoxylin-eosin (H&E) staining.

Results

The severity of lesions in the ivermectin group was reduced compared to the IMQ group, with a significant decrease in the average PASI scores. The results of fluorescence immunostaining showed that topical administration of IVM-gel reduced inflammation by decreasing Toll-like receptor 4 (TLR4) levels and p65 nuclear factor kappa-B (NF-κB). Furthermore, findings from H&E staining revealed that IVM-gel decreased dermal fibrosis, epidermal thickness, and infiltration of inflammatory cells caused by IMQ.

Conclusion

Based on the obtained results, it can be concluded that IVM-gel can effectively reduce psoriasis lesions due to its therapeutic properties, such as anti-inflammatory effects via targeting TLR4/p65 NF-κB.

An initial investigation of transcutaneous delivery of plasmid DNA encoding interleukin-10 for the treatment of psoriatic skin conditions

Psoriasis is a chronic immune-mediated skin disorder characterized by intense local inflammation, epidermal hyperplasia, and leukocyte infiltration. Current treatment approaches for psoriasis aim to alleviate symptoms and prevent disease progression, including systemically administered drugs with whole body side effects. Despite some advances in psoriasis treatment, success has been quite limited. To begin to address this challenge, we undertook an initial investigation of whether transcutaneous delivery of an endogenous anti-inflammatory cytokine could provide an effective, local treatment of psoriatic-like skin conditions. To do this, we utilized a previously documented rodent model of psoriasis, induced via a single topical application of Imiquimod (IMQ) to the shaved back of rats. The therapeutic approach used for this initial investigation was delivery of plasmid DNA encoding rat interleukin-10 (pDNA-rIL10), a non-viral gene therapy approach previously shown to be effective in suppressing neuroinflammatory disorders after localized delivery either intracerebrally or intrathecally. Translation of this CNS therapeutic for use in psoriatic-like skin disorders required reformulation to enable transcutaneous delivery. Toward that end, pDNA-rIL10 was topically applied in Lipoderm HMW, a base explicitly designed to deliver higher molecular weight compounds into skin. Here we show that a single topical application of pDNA-rIL10 in Lipoderm HMW was effective in decreasing mRNA levels of pro-inflammatory cytokines as well as reducing the recruitment of T-cells to IMQ-treated skin. Furthermore, this transcutaneous IL-10 gene therapy decreased signs of skin inflammation, reflected by reduced erythema. Moreover, the results provide an initial indication that IL10 may stimulate hair regrowth in psoriatic-like skin.

Repurposing an epithelial sodium channel inhibitor as a therapy for murine and human skin inflammation

Inflammatory skin disease is characterized by a pathologic interplay between skin cells and immunocytes and can result in disfiguring cutaneous lesions and systemic inflammation. Immunosuppression is commonly used to target the inflammatory component; however, these drugs are often expensive and associated with side effects. To identify previously unidentified targets, we carried out a nonbiased informatics screen to identify drug compounds with an inverse transcriptional signature to keratinocyte inflammatory signals. Using psoriasis, a prototypic inflammatory skin disease, as a model, we used pharmacologic, transcriptomic, and proteomic characterization to find that benzamil, the benzyl derivative of the US Food and Drug Administration-approved diuretic amiloride, effectively reversed keratinocyte-driven inflammatory signaling. Through three independent mouse models of skin inflammation (Rac1G12V transgenic mice, topical imiquimod, and human skin xenografts from patients with psoriasis), we found that benzamil disrupted pathogenic interactions between the small GTPase Rac1 and its adaptor NCK1. This reduced STAT3 and NF-κB signaling and downstream cytokine production in keratinocytes. Genetic knockdown of sodium channels or pharmacological inhibition by benzamil prevented excess Rac1-NCK1 binding and limited proinflammatory signaling pathway activation in patient-derived keratinocytes without systemic immunosuppression. Both systemic and topical applications of benzamil were efficacious, suggesting that it may be a potential therapeutic avenue for treating skin inflammation.

Topical application of phenformin ameliorates the psoriasis-like inflammatory response via the inhibition of c-Myc expression in keratinocytes

BACKGROUND

Psoriasis is a chronic inflammatory skin disease characterized by a complex pathogenesis involving various types of cells and cytokines. Among those, the pro-inflammatory cytokine IL-23/IL-17A axis plays a crucial role in the development and rapid progression of psoriasis. Phenformin, a derivative of metformin and a member of the biguanide class of drugs, exhibits superior anti-inflammatory and anti-tumor efficacy compared to metformin. However, the potential role of phenformin in anti-psoriatic skin inflammation has not been explored.

METHODS

In this study, we utilized a mouse model of psoriasis and an in vitro model using human keratinocytes to investigate whether phenformin can suppress psoriasis-like inflammatory responses.

RESULTS

Our results demonstrate that the topical application of phenformin significantly inhibited acute skin inflammatory responses in the psoriasis mouse model induced by imiquimod (IMQ). Additionally, phenformin suppressed the expression of psoriasis-related cytokines IL-17, IL-23, IL-8, and S100A8/S100A9 in an in vitro psoriatic keratinocyte model induced by IMQ. Furthermore, we found that IMQ-induced psoriatic skin and IMQ-treated keratinocytes exhibited high expression of the c-Myc gene, which was downregulated by phenformin. The c-Myc inhibitor JQ1 similarly inhibited the psoriatic inflammatory response and the expression of psoriasis-related cytokines in both in vitro and in vivo models.

CONCLUSION

phenformin ameliorates the psoriasis-like inflammatory response by inhibiting c-Myc expression in keratinocytes, suggesting its potential as a topical drug for the treatment of psoriasis.

Role of Vitamin C on methotrexate-induced nephrotoxicity in psoriasis context: A preclinical assessment

Methotrexate (MTX) is the most prescribed drug for systemic treatment of psoriasis. However, its clinical use is limited by its nephrotoxicity, which antioxidants can attenuate. This study evaluates the impact of vitamin C (vitC), a well-known antioxidant, on nephrotoxicity induced by high MTX doses in the context of psoriasis. To achieve this purpose, the kidney injury triggered by acute MTX exposure was established in an imiquimod-induced psoriasis-like mouse model. Mice were randomly divided into six groups: group 1 (control); group 2 (Imiquimod, IMQ), group 3 (IMQ+vitC 175 mg/kg/day); group 4 (MTX 20 mg/kg i.p); group 5 (IMQ+MTX 20 mg/kg) and group 6 (IMQ+MTX 20 mg/kg + vitC 175 mg/kg/day). The effects of these treatments were determined by considering the evolution of IMQ-induced skin lesions and serum creatinine levels. Moreover, histopathological analysis, lipid peroxidation, oxidative stress, and TNF-α production were determined in kidney tissue. Results showed that vitC attenuates renal damage in the context of IMQ-induced psoriasis. However, the opposite occurs when administered with IMQ+MTX, worsening skin psoriasis lesions and exacerbating acute renal tubular necrosis and oxidative DNA damage. These results establish new clues about the MTX-induced nephrotoxicity in the psoriasis context and the putative protective effects of vitC. It suggests that vitC supplementation could help attenuate the renal damage promoted by the psoriatic pathological environment. However, it should be avoided in psoriasis patients with renal dysfunction treated with MTX.

Immunomodulatory role of Trichinella spiralis-derived antigen on imiquimod-induced psoriasis in mice model

The immunomodulatory activity of parasites has been extensively investigated in multiple immune-related diseases. However, dermatological diseases have been off the list for a long time despite their vast incidence and the deleterious consequences of some of them. This study explored the immunomodulatory role of autoclaved Trichinella spiralis (T. spiralis) larvae antigen (ATSLA) as a psoriasis immunotherapeutic candidate in a mice model. Psoriasis was induced in Swiss albino mice using commercial imiquimod cream (IMQ). Mice were randomly divided into the IMQ untreated control group and the IMQ treated group that was treated with ATSLA twice, on day 0 and day 3. Additional mice served as normal controls. Assessment of skin thickness, erythema, and scales was recorded. Total skin scores were calculated. Skin MDA levels, splenic indices, serum and skin IL-23, and tumor necrosis factor alpha (TNF-α) were measured. Skin sections were stained with H&E and immune stained for CD68-positive cells using immunohistochemistry. Treatment with ATSLA significantly reduced skin thickness, erythema, scales, and total skin scores in the IMQ-treated group compared to the untreated control. This was accompanied by a reduction in the splenic index, skin MDA levels, IL-23, and TNF-α in both the skin and serum of the treated group. Pathologically, skin sections of the treated group showed less epidermal thickness, acanthosis, hyperkeratosis, and CD68 cell count. The study concluded the immunotherapeutic activity of ATSLA in experimental psoriatic skin lesions. This will enrich the psoriasis immunotherapeutic list with novel candidates of parasitic origin.

Niosomal gel improves dermal delivery of nimbolide: a promising approach for treatment of psoriasis

Aim: Psoriasis is a chronic inflammatory skin disorder characterized by the excessive proliferation of keratinocytes, forming thickened skin plaques due to immune-mediated cytokine responses. Delivering drugs through this barrier to target inflamed tissues remains challenging. Nimbolide (NIM), known for its anti-inflammatory and anticancer properties, shows promise in managing psoriasis. However, its efficacy is limited by its inability to penetrate the thickened horny layer of the skin. To overcome this obstacle, we have developed Nim-loaded niosomal (Nio) formulations (NIM Nio) aimed at improving dermal delivery and achieving localized sustained release at psoriasis-affected sites.Methods: The formulation characteristics were assessed using Zeta sizer, Transmission Electron Microscopy (TEM), and High-performance liquid chromatography (HPLC). The optimized formulation was evaluated for anti-psoriatic potential compared to Nim alone by using molecular techniques such as Confocal Microscopy, Flow cytometry, enzyme-linked immunosorbent assay (ELISA), and Western blotting.Results: NIM Nio showed effective penetration into psoriatic skin, resulting in reductions in keratinocyte hyperproliferation, oxidative stress, splenomegaly, inflammatory cytokines, Psoriasis Area and Severity Index (PASI), and rete ridges compared to NIM alone.Conclusion: Our findings underscore the significant anti-proliferative, antioxidant, and anti-inflammatory properties of NIM Nio in psoriasis, demonstrating its potential as a promising therapeutic option for this challenging condition.

Topical treatment of tyrosine kinase 2 inhibitor through borneol-embedded hydrogel: Evaluation for preventive, therapeutic, and Recurrent management of psoriasis

Psoriasis, an immune-mediated inflammatory skin disorder characterized by a chronically relapsing-remitting course, continues to be primarily managed through topical therapy. While oral administration of tyrosine kinase 2 inhibitors (TYK2i) stands as an effective approach for psoriasis treatment, the potential efficacy of topical application of TYK2i remains unexplored. Herein, the carbomer/alginic acid hydrogel is embedded with borneol (BO) as a new topical carrier of TYK2i for achieving enhanced transdermal permeation and anti-psoriasis efficacy. The hydrogel system, i.e., TYK2i-BO-gel, exhibits significantly improved preventative and therapeutic effects in mice models of psoriasiform dermatitis, as evidenced by phenotypical images, psoriasis severity score index (PSI), histology, immunohistochemical staining, and PCR analysis. Remarkably, TYK2i-BO-gel outperforms conventional topical corticosteroid therapy by significantly preventing psoriatic lesion recurrence as measured by a nearly 50 % reduction in ear thickness changes (p < 0.0001), PSI (p < 0.0001) and epidermal thickness (p < 0.05). Moreover, a strengthened anti-inflammatory effect caused by TYK2i-BO-gel is seen in a human skin explant model, implying its potential application for human patients. With the addition of BO, the TYK2i-BO-gel not only increases skin permeability but also inhibits the expression of antimicrobial peptides in keratinocytes and facilitates the anti-Th17 response of TYK2i with suppressed activation of STAT3. Therefore, this work represents the accessibility and effectiveness of TYK2i-BO-hydrogel as a new topical formulation for anti-psoriasis management and shows great potential for clinical application.

Tanshinol ameliorates imiquimod-induced psoriasis by inhibiting M1 macrophage polarization through suppression of the notch signaling pathway

BACKGROUND

Psoriasis is a common immune-related chronic inflammatory skin disease, often accompanied by significant itching, and once diseased, the course of the disease lasts for most of the lifetime. Tanshinol (TAN) is an active ingredient of Salvia miltiorrhiza, which possesses pharmacological effects such as anti-inflammatory and antioxidant properties. However, the effects of TAN on psoriasis have not been widely reported. Therefore, the aim of this study was to investigate the therapeutic effects and mechanisms of TAN in psoriasis.

METHODS

An imiquimod (IMQ)-induced psoriasis mouse model was constructed and treated with different doses of TAN to observe the changes in skin lesion phenotype, macrophage polarization, inflammation and Notch signaling pathway in mice. Further removal of macrophages or inhibition or activation of Notch signaling pathway was performed to examine the changes in skin lesion phenotype, macrophage polarization, inflammation and Notch signaling pathway in mice. In addition, in vitro experiments verified that TAN regulates RAW264.7 macrophage polarization and cytokine secretion through the Notch pathway.

RESULTS

The results showed that TAN alleviated IMQ-induced skin lesions and pathological phenotypes in psoriasis mice and inhibited Notch signaling pathway and M1-type macrophage polarization. Moreover, macrophage clearance and Notch signaling pathway activation inhibited the effect of TAN on psoriasis. Further in vitro experiments showed that Notch agonists reversed the effects of TAN on macrophage polarization and inflammatory cytokines.

CONCLUSIONS

Collectively, these findings suggest that TAN may exert a therapeutic effect on psoriasis by inhibiting the Notch signaling pathway and thus M1-type macrophage polarization.

Green preparation and evaluation of the anti-psoriatic activity of vesicular elastic nanocarriers of kojic acid from Aspergillus oryzae N12: Repurposing of a dermo-cosmetic lead

Psoriasis is a skin disorder characterized by impaired epidermal differentiation that is regularly treated by systemic drugs with undesirable side effects. Based on its anti-inflammatory, antiproliferative and anti-melanoma attributes, the fungal metabolite kojic acid represents an attractive candidate for anti-psoriatic research. The present work aims to investigate an efficient topical bio-friendly vesicular system loaded with kojic acid isolated from Aspergillus oryzae as an alternative way for the management of psoriasis to avoid systemic toxicity. Kojic acid-loaded spanlastics were prepared by ethanol injection technique, employing span 60 along with brij 35 and cremophor rh40 as edge activators, with the complete in vitro characterization of the developed nanoplatform. The selected formulation displayed a spherical morphology, an optimum particle size of 234.2 ± 1.65 nm, high entrapment efficiency (87.4% ± 0.84%) and significant sustained drug release compared with the drug solution. In vivo studies highlighted the superior relief of psoriasis symptoms and the ability to maintain healthy skin with the least changes in mRNA expression of inflammatory cytokines, achieved by the developed nanoplatform compared to kojic acid solution. Moreover, the in vivo histopathological studies confirmed the safety of the topically applied spanlastics. In addition, the molecular mechanism was approached through in vitro assessment of cathepsin S and PDE-4 inhibitory activities and in silico investigation of kojic acid docking in several anti-psoriatic drug targets. Our results suggest that a topically applied vesicular system loaded with kojic acid could lead to an expansion in the dermo-cosmetic use of kojic acid as a natural bio-friendly alternative for systemic anti-psoriatic drugs.

Matrix metalloproteinase landscape in the imiquimod-induced skin inflammation mouse model

Inflammation and autoimmunity are known as central processes in many skin diseases, including psoriasis. It is therefore important to develop pre-clinical models that describe disease-related aspects to enable testing of pharmaceutical drug candidates and formulations. A widely accepted pre-clinical model of psoriasis is the imiquimod (IMQ)-induced skin inflammation mouse model, where topically applied IMQ provokes local skin inflammation. In this study, we investigated the abundance of a subset of matrix metalloproteinases (MMPs) in skin from mice with IMQ-induced skin inflammation and skin from naïve mice using targeted proteomics. Our findings reveal a significant increase in the abundance of MMP-2, MMP-7, MMP-8, and MMP-13 after treatment with IMQ compared to the control skin, while MMP-3, MMP-9, and MMP-10 were exclusively detected in the IMQ-treated skin. The increased abundance and broader representation of MMPs in the IMQ-treated skin provide valuable insight into the pathophysiology of skin inflammation in the IMQ model, adding to previous studies on cytokine levels using conventional immunochemical methods. Specifically, the changes in the MMP profiles observed in the IMQ-treated skin resemble the MMP patterns found in skin lesions of individuals with psoriasis. Ultimately, the differences in MMP abundance under IMQ-induced inflammation as compared to non-inflamed control skin can be exploited as a model to investigate drug efficacy or performance of drug delivery systems.

Ionic Liquid-Mediated Transdermal Delivery of Organogel Containing Cyclosporine A for the Effective Treatment of Psoriasis

The dermal delivery of peptide therapeutics that are of high molecular weight is a challenge. Cyclosporine A (CsA) is a cyclic undecapeptide with poor aqueous solubility and high molecular weight (1202 Da) indicated for psoriasis. The objective of the study was to evaluate the effect of ionic liquids mixed with the Pluronic F127 matrix in skin permeation of CsA and its efficacy in psoriasis treatment. Choline and geranic acid (CAGE) ionic liquids in a 1:2 molar ratio were mixed with Pluronic F127 (22.7%) and PEG 400 (45%) to prepare an organogel formulation. The CsA-loaded CAGE (CsA-CAGE) and CAGE-Pluronic F127 gels (CsA-CAGE-P gel) were characterized for physical and rheological characteristics. The skin transport studies showed that free CsA did not permeate across the excised porcine skin after 48 h. The amount of CsA permeated across the oleic acid (0.25% v/v) and palmitic acid (0.25% w/v) cotreated skin was found to be 244 ± 4 and 1236 ± 17 μg/cm2, respectively. The application of CsA-CAGE and CsA-CAGE-P gel enhanced CsA flux by 110- and 135-fold, respectively, compared with the control. The thermal analysis and biophysical studies changed the barrier property of the skin significantly (p < 0.05) after incubation with CAGE and CAGE-P gel. The pharmacokinetic studies in the rat model showed that topical application of CsA-CAGE-P gel provided 2.6- and 1.9-fold greater C max and AUC0-t, respectively, compared to the control group. In vitro-in vivo level A correlations were established with R 2 values of 0.991 and 0.992 for both linear and polynomial equations for the CsA-CAGE-P gel formulation using the Wagner-Nelson method. The topical application of CsA-CAGE-P gel (10 mg/kg) on an imiquimod-induced plaque psoriatic model reduced the area of the psoriasis and severity index (PASI) score significantly for erythema and scaling, reversing the changes to skin thickness, blood flow rate, and transepidermal water loss. Together, CAGE-Pluronic F127 organogel was developed as an effective topical formulation for the local and systemic delivery of CsA for the treatment of psoriasis.

Mouse Models of Itch

Murine models are vital preclinical and biological tools for studying itch. In this paper, we explore how these models have enhanced our understanding of the mechanisms underlying itch through both acute and chronic itch models. We provide detailed protocols and recommend experimental setups for specific models to guide researchers in conducting itch research. We distinguish between what constitutes a bona fide pruritogen versus a stimulus that causes pruritogen release, an acute itch model versus a chronic itch model, and how murine models can capture aspects of pruritus in human disease. Finally, we highlight how mouse models of itch have transformed our understanding and development of therapeutics for chronic pruritus in patients.

Mitigative Effects of Topical Norfloxacin on an Imiquimod-Induced Murine Model of Psoriasis

Psoriasis is a chronic, inflammatory dermatosis characterized by thickened, reddened, and scaly skin lesions. Norfloxacin is a fluoroquinolone antibiotic with enhanced antioxidant, anti-inflammatory, and immunomodulatory bioactivities. The aim of this study was to figure out the possible impact of topical norfloxacin on an imiquimod-induced model of psoriasis in mice. Thirty albino-type mice were split into five distinct groups of six animals each. The control group included healthy mice that had not received any treatment. The induction group was given the vehicle 2 h after the topical imiquimod, once daily for 8 days. Two hours after receiving topical imiquimod, the treatment groups including calcipotriol, norfloxacin 2.5%, and norfloxacin 5% were given topical ointments containing calcipotriol 0.005%, norfloxacin 2.5%, and norfloxacin 5%, for 8 days. Topical norfloxacin ointment significantly reduced the severity of imiquimod-exacerbated psoriatic lesions including erythema, shiny-white scaling, and acanthosis and fixed histological abnormalities. Furthermore, imiquimod-subjected mice treated with a higher concentration of norfloxacin ointment exhibited dramatically lower skin levels of inflammation-related biomarkers like IFN-γ, TNF-α, IL-6, IL-17A, IL-23, and TGF-β but higher levels of IL-10. They also demonstrated a notable decrease in angiogenesis parameters such as VEGF and IL-8, a substantial reduction in oxidative indicators like MDA and MPO, and a considerable rise in antioxidant enzymes like SOD and CAT. This study offers novel evidence that norfloxacin may assist in controlling inflammatory dermatoses like psoriasis by minimizing the severity of psoriatic plaques, correcting histological alterations, and diminishing the production of inflammatory, oxidative, and angiogenetic parameters.

Phenotypical and biochemical characterization of murine psoriasiform and fibrotic skin disease models in Stabilin-deficient mice

Stabilin-1 (Stab1) and Stabilin-2 (Stab2) are scavenger receptors expressed by liver sinusoidal endothelial cells (LSECs). The Stabilin-mediated scavenging function is responsible for regulating the molecular composition of circulating blood in mammals. Stab1 and Stab2 have been shown to influence fibrosis in liver and kidneys and to modulate inflammation in atherosclerosis. In this context, circulating and localized TGFBi and POSTN are differentially controlled by the Stabilins as their receptors. To assess Stab1 and Stab2 functions in inflammatory and fibrotic skin disease, topical Imiquimod (IMQ) was used to induce psoriasis-like skin lesions in mice and Bleomycin (BLM) was applied subcutaneously to induce scleroderma-like effects in the skin. The topical treatment with IMQ, as expected, led to psoriasis-like changes in the skin of mice, including increased epidermal thickness and significant weight loss. Clinical severity was reduced in Stab2-deficient compared to Stab1-deficient mice. We did not observe differential effects in the skin of Stabilin-deficient mice after bleomycin injection. Interestingly, treatment with IMQ led to a significant increase of Stabilin ligand TGFBi plasma levels in Stab2-/- mice, treatment with BLM resulted in a significant decrease in TGFBi levels in Stab1-/- mice. Overall, Stab1 and Stab2 deficiency resulted in minor alterations of the disease phenotypes accompanied by alterations of circulating ligands in the blood in response to the disease models. Stabilin-mediated clearance of TGFBi was altered in these disease processes. Taken together our results suggest that Stabilin deficiency-associated plasma alterations may interfere with preclinical disease severity and treatment responses in patients.

Combined photodynamic therapy and hollow microneedle approach for effective non-invasive delivery of hypericin for the management of imiquimod-induced psoriasis

BACKGROUND

Conventional topical psoriasis treatments suffer from limited delivery to affected areas and skin irritation due to high local drug concentration.

PURPOSE

This study aims to prepare hypericin (HYP) loaded nanostructured lipid carriers (NLCs) and their application in psoriasis treatment through intradermal administration using hollow microneedles assisted by photodynamic therapy.

METHODS

The colloidal characteristics of NLCs, entrapment efficiency and morphology were evaluated. An ex-vivo skin distribution study was conducted along with testing the in vivo antipsoriatic activity in mice with the imiquimod-induced psoriasis model.

RESULTS

The particle size and zeta potential of HYP-NLCs were 167.70 nm and -18.1, respectively. The ex-vivo skin distribution study demonstrated the superior distribution of HYP-NLCs to a depth of 1480 µm within the skin layers relative to only 750 µm for free HYP. In vivo studies revealed that the levels of NF-KB, IL 6, MMP1, GSH, and catalase in the group treated with HYP-NLCs in the presence of light were comparable to the negative control.

CONCLUSIONS

The histopathological inspection of dissected skin samples reflected the superiority of HYP-NLCs over HYP ointment. This could be ascribed to the effect of nanoencapsulation on improving HYP properties besides the ability of hollow microneedles to ensure effective HYP delivery to the affected psoriatic area.

Evaluation of Clobetasol and Tacrolimus Treatments in an Imiquimod-Induced Psoriasis Rat Model

Psoriasis is a chronic inflammatory skin disorder characterized by keratinocyte hyperproliferation, inflammation, and aberrant differentiation. Imiquimod-induced psoriasis in rodent models has been widely used to study the pathogenesis of the disease and evaluate potential therapeutic interventions. In this study, we investigated the efficacy of two commonly used treatments, Clobetasol and Tacrolimus, in ameliorating psoriatic symptoms in an Imiquimod-induced psoriasis Wistar rat model. Interestingly, rat models are poorly evaluated in the literature despite rats displaying several advantages in evaluating pharmacological substances. Psoriasis-like skin lesions were induced by topical application of Imiquimod cream on shaved dorsal skin for seven consecutive days. Following induction, rats in the treatment groups received either a Clobetasol or Tacrolimus ointment once daily for one week, while the control group did not receive any application. Disease severity was assessed using clinical scoring, histological examination, and measurement of proinflammatory cytokine levels. Both Clobetasol and Tacrolimus treatments significantly reduced psoriatic lesion severity compared to the control group. Clinical scoring revealed a decrease in erythema, scaling, transepidermal water loss, and thickness of skin lesions in both treatment groups with a more marked effect with Clobetasol. Histological analysis demonstrated reduced epidermal hyperplasia in treated animals compared to controls. Furthermore, Clobetasol led to a significant reduction in the expression levels of the interleukin-17 (IL-17a and IL-17f) proinflammatory cytokines in lesioned skin. Overall, our findings demonstrated the therapeutic efficacy of both Clobetasol and, in a modest manner, Tacrolimus in attenuating Imiquimod-induced psoriasis-like symptoms in a rat model. These results support the clinical use of these agents in the management of psoriasis and mitigating psoriatic inflammation. They also provide insights into the use of rats as a relevant species for the Imiquimod-induced psoriasis model.

Ameliorative effects of topical ramelteon on imiquimod-induced psoriasiform inflammation in mice

Psoriasis is a long-lasting, immune-related inflammatory skin disease that affects 2-3% of the global population. It is distinguished by erythematous, silvery, and scaly patches. Ramelteon is a type of melatonin agonist that is used to treat insomnia. It has enhanced non-classical immunomodulatory and anti-inflammatory activities. The aim of the study is to assess the ameliorative effects of topical ramelteon on imiquimod (IMQ)-aggravated psoriasiform-like dermatosis in mice. The 32 albino mouse males were placed into six groups of eight animals, all of them. With the exception of the control group, all groups gained a once-a-day regimen of topical imiquimod 5% cream at a dose of 62.5 mg for eight uninterrupted days, while mice in the control group gained vaseline-based ointment alternately. Immediately after an 8-day induction period in the imiquimod group, mice in the clobetasol and ramelteon treatment groups obtained a twice-daily regimen of topical clobetasol propionate 0.05% ointment and 0.1% ointment, respectively, for a further 8 days. This extends the total duration of the experimental study to 16 continuous days. The findings of our study found that ramelteon significantly mitigated the concentrations of inflammatory cytokines in the skin tissue, including interleukin (IL)-6, IL-17A, IL-23, tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor (VEGF), as well as the scores associated with psoriatic lesions, including erythema, scaling, skin thickening, ear thickness, and overall cumulative PASI scores. Additionally, the anti-inflammatory impact of ramelteon was achieved by markedly increasing IL-10 levels in the skin tissue and correcting cutaneous histopathological alterations. Ramelteon ointment (0.1%) was comparable to that of clobetasol (0.05%) ointment in alleviating a mouse model of imiquimod-induced psoriasiform inflammation; this is probably due to its potential anti-inflammatory and immunomodulatory activities. Therefore, ramelteon could be a good additive option for therapeutic management of immune-triggered inflammatory conditions such as psoriasis.

Short-chain fatty acids ameliorate imiquimod-induced skin thickening and IL-17 levels and alter gut microbiota in mice: a metagenomic association analysis

Short-chain fatty acids (SCFAs) have been proposed to have anti-inflammatory effects and improve immune homeostasis. We aimed to examine the effects of SCFAs on skin phenotype, systemic inflammation, and gut microbiota in mice with psoriasis-like inflammation. Imiquimod (IMQ)-treated C57BL/6 mice served as the study model. We conducted a metagenomic association study of IMQ-mice treated with SCFAs or anti-IL-17 antibody using whole-genome shotgun sequencing. The associations among SCFA supplements, skin thickness, circulating inflammatory profiles, and fecal microbiota profiles were investigated. The microbiome study was performed using pipelines for phylogenetic analysis, functional gene analysis, and pathway analysis. In IMQ-treated mice, there were increases in skin thickness and splenic weight, as well as unique fecal microbial profiles. SCFAs ameliorated IMQ-induced skin thickening, splenic weight gain, and serum IL-17F levels, with results that were comparable with those receiving anti-IL-17 treatment. IMQ-treated mice receiving SCFAs had greater microbial diversity than mice treated with IMQ alone. SCFAs and anti-IL17 treatment were associated with alteration of gut microbiota, with increased prevalences of Oscillospiraceae and Lachnopiraceae and decreased prevalences of Muribaculaceae and Bacteroides, which have been predicted to be associated with increased glycan degradation, phenylalanine metabolism, and xylene degradation. SCFAs may mitigate IMQ-induced skin thickening and IL-17F levels and alter fecal microbiota profiles in IMQ-treated mice.

Evaluation of Kynu, Defb2, Camp, and Penk Expression Levels as Psoriasis Marker in the Imiquimod-Induced Psoriasis Model

Background

Psoriasis is a noncontagious auto-inflammatory chronic skin disease. So far, some of the inflammatory genes were upregulated in mouse model of psoriasis. This study examined changes in skin mRNA expression of L-kynureninase (Kynu), cathelicidin antimicrobial peptide (Camp), beta-defensin 2 (Defb2), and proenkephalin (Penk) in a mouse model of imiquimod-induced psoriasis.

Materials and Methods

Tree groups of C57BL/6 female mice were allocated. The imiquimod (IMQ) cream was administered to the mice dorsal skin of the two groups to induce psoriatic inflammation. In the treatment group, IMQ was administered 10 min after hydrogel-containing M7 anti-IL-17A aptamer treatment. Vaseline (Vas) was administered to the negative control group. The psoriatic skin lesions were evaluated based on the psoriasis area severity index (PASI) score, histopathology, and mRNA expression levels of Kynu, Camp, Defb2, and Penk using real-time PCR. In order to assess the systemic response, the spleen and lymph node indexes were also evaluated.

Results

The PASI and epidermal thickness scores were 6.01 and 1.96, respectively, in the IMQ group, and they significantly decreased after aptamer administration to 1.15 and 0.90, respectively (P < 0.05). Spleen and lymph node indexes showed an increase in the IMQ group, followed by a slight decrease after aptamer treatment (P > 0.05). Additionally, the mRNA expression levels of Kynu, Defb2, Camp, and Penk genes in the IMQ-treated region showed a significant 2.70, 4.56, 3.29, and 2.61-fold increase relative to the Vas mice, respectively (P < 0.05). The aptamer-treated region exhibited a significant decrease in these gene expression levels (P < 0.05). A positive correlation was found between Kynu, Penk, and Camp expression levels and erythema, as well as Camp expression with PASI, scaling, and thickness (P < 0.05).

Conclusion

According to our results, it seems that Kynu, Camp, and Penk can be considered appropriate markers for the evaluation of psoriasis in IMQ-induced psoriasis. Also, the anti-IL-17 aptamer downregulated these important genes in this mouse model.

Therapeutic Effect of Lecigel, Cetiol®CC, Activonol-6, Activonol-M, 1,3-Propanediol, Soline, and Fucocert® (LCAA-PSF) Treatment on Imiquimod-Induced Psoriasis-like Skin in Mice

The individual ingredients of 1,3-Propanediol, Soline, and Fucocert® (PSF) are often used as cosmetic formulations in skin care. In addition, the mixture of Lecigel, Cetiol®CC, Activonol-6, and Activonol-M (LCAA) is often used as a cosmetic base. However, whether the combination of LCAA with PSF (LCAA-PSF) exerts a therapeutic effect on psoriasis remains unclear. In this study, mice induced with imiquimod (IMQ) were divided into three groups and administered 100 mg/day of LCAA, 100 mg/day of LCAA-PSF, or Vaseline on the dorsal skin of each mouse. Weight-matched mice treated with Vaseline alone were used as controls. Hematoxylin and eosin (H&E) staining and enzyme-linked immunosorbent assay(ELISA) were used to assess tissue morphology and inflammatory cytokines. RNA sequencing analysis was used to predict the mechanism underlying the action of LCAA-PSF against psoriasis, while immunohistochemical analysis validation was used to identify pertinent molecular pathways. The results demonstrated that LCAA-PSF alleviated IMQ-induced keratinocyte differentiation/ proliferation bydecreasingthe serum levels of inflammatory cytokines such as IL-6, TNF-α, IL-23, and IL-17A and the epidermisof TGFβ, Ki67, CK5/6, and VEGF expression, which is associated with angiogenesis and keratinocyte differentiation/ proliferation. These findings highlight the antipsoriatic activity of LCAA-PSF in a psoriasis-like mouse model and suggest this may occurvia the inhibition of inflammatory factor secretionand the TGFβ-related signal pathway.

Discovery of Novel Small Molecule Dual Inhibitor Targeting Toll-Like Receptors 7 and 9

The aberrant secretion of proinflammatory cytokines by immune cells is the principal cause of inflammatory diseases, such as systemic lupus erythematosus and rheumatoid arthritis. Toll-like receptor 7 (TLR7) and TLR9, sequestered to the endosomal compartment of dendritic cells and macrophages, are closely associated with the initiation and progression of these diseases. Therefore, the development of drugs targeting dysregulated endosomal TLRs is imperative to mitigate systemic inflammation. Here, we applied the principles of computer-aided drug discovery to identify a novel low-molecular-weight compound, TLR inhibitory compound 10 (TIC10), and its potent derivative (TIC10g), which demonstrated dual inhibition of TLR7 and TLR9 signaling pathways. Compared to TIC10, TIC10g exhibited a more pronounced inhibition of the TLR7- and TLR9-mediated secretion of the proinflammatory cytokine tumor necrosis factor-α in a mouse macrophage cell line and mouse bone marrow dendritic cells in a concentration-dependent manner. While TIC10g slightly prevented TLR3 and TLR8 activation, it had no impact on cell surface TLRs (TLR1/2, TLR2/6, TLR4, or TLR5), indicating its selectivity for TLR7 and TLR9. Additionally, mechanistic studies suggested that TIC10g interfered with TLR9 activation by CpG DNA and suppressed downstream pathways by directly binding to TLR9. Western blot analysis revealed that TIC10g downregulated the phosphorylation of the p65 subunit of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinases (MAPKs), including extracellular-signal-regulated kinase, p38-MAPK, and c-Jun N-terminal kinase. These findings indicate that the novel ligand, TIC10g, is a specific dual inhibitor of endosomal TLRs (TLR7 and TLR9), disrupting MAPK- and NF-κB-mediated proinflammatory gene expression.

Novel effect of topical Roquinimex and its combination with Clobetasol on an imiquimod-induced model of psoriasis in mice

Psoriasis is a chronic inflammatory skin condition affecting multiple systems and the skin, with topical therapy representing the fundamental treatment modality for psoriasis. Investigate the effect of topical Roquinimex (ROQ) alone and combined with Clobetasol propionate (CLO) on imiquimod (IMQ)-induced mouse model as a novel approach to treating psoriasis. Sixty male Swiss Albino mice were divided into six groups of ten mice; all groups except the negative control received IMQ cream 5% (62.5 mg) as a once-daily topical application for six days. On the seventh day, five groups (except negative control) received one of the following treatments for eight days: no treatment (positive control), Petrolatum gel 15% as a twice-daily topical application (Petrolatum control), CLO 0.05% ointment once daily, ROQ ointment 1% w/w twice daily topically, topical preparation of 0.025% CLO ointment combined with ROQ ointment 0.5% w/w twice daily; the total duration of the study is 14 days. The clinical, pathological, and laboratory effects were then measured. The use of ROQ ointment alone or combined with CLO resulted in significant improvement in psoriasis lesions (measured by Baker's and PASI scores) compared to positive control groups (2.15±1.08, 1.60±0.61, 9.00±0.00, and 7.60±0.84, respectively for Baker's score) (1.50±1.08, 1.30±0.95, 11.70±0.48, 9.30±0.67, respectively for PASI score), a similar improvement seen for various inflammatory markers, including interleukin (IL)-10 (140.53±60.68, 285.63±92.16, 31.83±3.03, and 92.50±27.13 pg/ml, respectively), IL-17 (126.58±40.98, 124.26±61.40, 553.04±141.32, and 278.52±100.27 pg/ml, respectively), tumor necrosis factor-α (72.34±23.40, 30.11±7.01, 807.13±500.06, and 281.79±240.17 pg/ml, respectively), and vascular endothelial growth factor (109.71±29.35, 80.96±24.58, 552.20±136.63, 209.56±73.31 pg/ml and respectively). Roquinimex exerts its antipsoriatic effect through multiple mechanisms; its combination treatment with Clobetasol is a promising therapy for managing psoriasis.

Posidonia oceanica (L.) Delile Is a Promising Marine Source Able to Alleviate Imiquimod-Induced Psoriatic Skin Inflammation

Psoriasis is a chronic immune-mediated inflammatory cutaneous disease characterized by elevated levels of inflammatory cytokines and adipokine Lipocalin-2 (LCN-2). Recently, natural plant-based products have been studied as new antipsoriatic compounds. We investigate the ability of a leaf extract of the marine plant Posidonia oceanica (POE) to inhibit psoriatic dermatitis in C57BL/6 mice treated with Imiquimod (IMQ). One group of mice was topically treated with IMQ (IMQ mice) for 5 days, and a second group received POE orally before each topical IMQ treatment (IMQ-POE mice). Psoriasis Area Severity Index (PASI) score, thickness, and temperature of the skin area treated with IMQ were measured in both groups. Upon sacrifice, the organs were weighed, and skin biopsies and blood samples were collected. Plasma and lesional skin protein expression of IL-17, IL-23, IFN-γ, IL-2, and TNF-α and plasma LCN-2 concentration were evaluated by ELISA. PASI score, thickness, and temperature of lesional skin were reduced in IMQ-POE mice, as were histological features of psoriatic dermatitis and expression of inflammatory cytokines and LCN-2 levels. This preliminary study aims to propose P. oceanica as a promising naturopathic anti-inflammatory treatment that could be introduced in Complementary Medicine for psoriasis.

Rodent models of dermatological disorders

To assess the possible beneficial effects of drugs and drug candidates, different dermatological disease models are available in rodents. These models are able to mimic one or more characteristic features of the disorders, but not completely recapitulate the pathogenesis of the human skin diseases. Therefore, to improve the technology many new models have been developed both by genetic engineering and by chemical or physical induction. Currently the in vivo rodent models provide the physiologically most relevant approach to produce the pathology related to the majority of dermatological diseases. In this short review some widely used animal techniques (psoriasis, allergic contact dermatitis, atopic dermatitis, wound healing, melanoma and non-melanoma type skin cancers and UV erythema) are shown which are currently applied in pharmacological, pharmacokinetic, pharmaceutical and dermatological research. First the main points of the human pathomechanism are shown and afterwards the rodent models are briefly discussed. Finally critical evaluation is provided by the authors. However, according to the 3R rule the number of experimental animals is strongly suggested to be reduced, therefore the advanced in vitro and ex vivo techniques become more and more important contrary to in vivo preclinical methods also in dermatological research. As it is described in the outlook section, although the 2D/3D in vitro and skin on-a-chip techniques are promising and have many advantages they are not able to completely substitute the animal models in their vascular, immunological, secretory and neural complexity.

Geniposide alleviates imiquimod-induced psoriasis-like skin lesions in mice via inhibition of angiogenesis

In this study, we aimed to evaluate the protective effect of geniposide (GEN) on imiquimod (IMQ)-induced psoriasis-like skin lesions in mice. Firstly, visual changes of psoriatic skin lesions were observed and the severity was recorded using psoriasis area and severity index (PASI) score. Histological changes were assessed by HE staining for epidermal thickness and Masson's staining for collagen fibers. Then, photographs of microvascular inside the skin were taken for macroscopic observation, and microscopic changes associated with angiogenesis were evaluated. Furthermore, expression of angiogenic factors were analyzed by ELISA, immunohistochemistry and immunofluorescence, separately. Lastly, the expression of VEGFR signaling-related proteins was detected by WB. Compared with control, IMQ drove a significant increment of epidermal thicknesses with higher PASI scores and more dermal collagen deposition. IMQ treatment led to abnormal keratinocyte proliferation, increased microvascular inside skin, growing production of angiogenesis-related factors, up-regulated expression of VEGFR1 and VEGFR2, and enhanced phosphorylation of p38. However, GEN significantly ameliorated the psoriatic skin lesions, the epidermal thickness, the formation of collagen fibers, and abnormal keratinocyte proliferation. Importantly, GEN inhibited angiogenesis, the production of angiogenic factors (VEGF-A, Ang-2, TNF-α, and IL-17A), and the proliferation of vascular endothelial cells. Simultaneously, GEN curbed the expression of VEGFR1, VEGFR2, p38, and P-p38 proteins involved in VEGFR signaling. Of note, the suppressive effect of GEN was reversed in the HUVECs with over-expressed VEGFR1 or VEGFR2 related to the cells without transfection. These findings suggest that VEGFR1 and VEGFR2 participate in the anti-angiogenesis of GEN in IMQ-induced psoriasis-like skin lesions in mice.

Local and Sustained Baricitinib Delivery to the Skin through Injectable Hydrogels Containing Reversible Thioimidate Adducts

Janus kinase (JAK) inhibitors are approved for many dermatologic disorders, but their use is limited by systemic toxicities including serious cardiovascular events and malignancy. To overcome these limitations, injectable hydrogels are engineered for the local and sustained delivery of baricitinib, a representative JAK inhibitor. Hydrogels are formed via disulfide crosslinking of thiolated hyaluronic acid macromers. Dynamic thioimidate bonds are introduced between the thiolated hyaluronic acid and nitrile-containing baricitinib for drug tethering, which is confirmed with 1H and 13C nuclear magnetic resonance (NMR). Release of baricitinib is tunable over six weeks in vitro and active in inhibiting JAK signaling in a cell line containing a luciferase reporter reflecting interferon signaling. For in vivo activity, baricitinib hydrogels or controls are injected intradermally into an imiquimod-induced mouse model of psoriasis. Imiquimod increases epidermal thickness in mice, which is unaffected when treated with baricitinib or hydrogel alone. Treatment with baricitinib hydrogels suppresses the increased epidermal thickness in mice treated with imiquimod, suggesting that the sustained and local release of baricitinib is important for a therapeutic outcome. This study is the first to utilize a thioimidate chemistry to deliver JAK inhibitors to the skin through injectable hydrogels, which has translational potential for treating inflammatory disorders.

A Novel Recombinant Human Filaggrin Segment (rhFLA-10) Alleviated a Skin Lesion of Atopic Dermatitis

Atopic dermatitis (AD), a prevalent chronic inflammatory skin disorder, is marked by impaired skin barrier function and persistent pruritus. It significantly deteriorates patients' quality of life, making it one of the most burdensome non-lethal skin disorders. Filaggrin plays a crucial role in the pathophysiology of barrier disruption in AD, interacting with inflammatory mediators. It is an integral part of the extracellular matrix architecture, serving to protect the skin barrier and attenuate the inflammatory cascade. In this study, we engineered a novel recombinant human filaggrin (rhFLA-10) expression vector, which was subsequently synthesized and purified. In vitro and ex vivo efficacy experiments were conducted for AD. rhFLA-10, at low concentrations (5 to 20 μg/mL), was non-toxic to HACaT cells, significantly inhibited the degranulation of P815 mast cells, and was readily absorbed by cells, thereby exerting a soothing therapeutic effect. Furthermore, rhFLA-10 demonstrated anti-inflammatory properties (p < 0.05). In vivo, efficacy experiments further substantiated that rhFLA-10 could effectively ameliorate AD in mice and facilitate the repair of damaged skin (p < 0.001). These findings underscore the considerable potential of rhFLA-10 in the treatment of AD.

Mathematical modeling of transdermal delivery of topical drug formulations in a dynamic microfluidic diffusion chamber in health and disease

Mathematical models of epidermal and dermal transport are essential for optimization and development of products for percutaneous delivery both for local and systemic indication and for evaluation of dermal exposure to chemicals for assessing their toxicity. These models often help directly by providing information on the rate of drug penetration through the skin and thus on the dermal or systemic concentration of drugs which is the base of their pharmacological effect. The simulations are also helpful in analyzing experimental data, reducing the number of experiments and translating the in vitro investigations to an in-vivo setting. In this study skin penetration of topically administered caffeine cream was investigated in a skin-on-a-chip microfluidic diffusion chamber at room temperature and at 32°C. Also the transdermal penetration of caffeine in healthy and diseased conditions was compared in mouse skins from intact, psoriatic and allergic animals. In the last experimental setup dexamethasone, indomethacin, piroxicam and diclofenac were examined as a cream formulation for absorption across the dermal barrier. All the measured data were used for making mathematical simulation in a three-compartmental model. The calculated and measured results showed a good match, which findings indicate that our mathematical model might be applied for prediction of drug delivery through the skin under different circumstances and for various drugs in the novel, miniaturized diffusion chamber.

Effect of stearyl alcohol on imiquimod-induced psoriasis-like skin inflammation in mice

Psoriasis is a chronic inflammatory skin disease. Topical medicines are the preferred treatment for mild to moderate psoriasis, but the effect of excipients used in semi-solid preparations on psoriasis-like skin inflammation is not fully understood. In the present study, we investigated the effect of stearyl alcohol, a commonly used excipient, on imiquimod (IMQ)-induced psoriasis-like skin inflammation in mice. Psoriasis-like skin inflammation was induced by topical IMQ treatment on the back of mice. Skin lesion severity was evaluated by using psoriasis area and severity index (PASI) scores. The skin sections were stained by haematoxylin-eosin and immunohistochemistry. Stearyl alcohol (20% in vaseline) treatment significantly reduced the IMQ-induced increase of PASI scores and epidermal thickness in mice. IMQ treatment increased the number of Ki67- and proliferating cell nuclear antigen (PCNA)-positive cells in the skin, and the increases were inhibited by stearyl alcohol (20% in vaseline) treatment. Stearyl alcohol treatment (1%, 5%, 10% in vaseline) dose-dependently ameliorated IMQ-induced increase of PASI scores and epidermal thickness in mice. Hexadecanol (20% in vaseline), stearic acid (20% in vaseline) and vaseline treatment had no significant effect on IMQ-induced psoriasis-like skin inflammation in mice. In conclusion, stearyl alcohol has the effect of improving IMQ-induced psoriasis-like skin inflammation in mice.