Magnolol may contribute to barrier function improvement on imiquimod-induced psoriasis-like dermatitis animal model via the downregulation of interleukin-23

Topical application of magnolol ameliorates psoriasis-like dermatitis by inhibiting NLRP3/Caspase-1 pathway and regulating tryptophan metabolism

Psoriasis (PSO) is a common inflammatory skin disease caused by multiple factors. Magnolia officinalis is an important medicinal plant in China, with various values such as ecology, medicine, food, and daily chemicals. However, its diverse application potential has not been fully explored. Magnolol (MGO) is the main active compound of Magnolia officinalis with significant anti-inflammatory effect. To investigate the application potential of MGO in inflammatory skin disease, the effects and underlying mechanisms of topical MGO treating psoriasis were explored in this study. Network pharmacology and molecular docking firstly predicted that topical MGO may treat psoriasis by regulating pyroptosis pathway and acting on caspase-1 (CASP1). In vitro experiments then demonstrated that MGO could inhibit the level of inflammatory cytokines and the key protein expression of NOD-like receptor protein 3 (NLRP3)/Caspase-1 pathway in lipopolysaccharide (LPS)-stimulated phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 cells. Meanwhile, MGO could inhibit CuSO4-induced neutrophils migration in Tg (mpx:EGFP) zebrafish by suppressing inflammation and pyroptosis. This study further indicated that topical application of MGO ameliorated imiquimod (IMQ)-induced psoriasis-like dermatitis by reducing the release of inflammatory factors and decreasing the key protein expression of pyroptosis-related NLRP3/Caspase-1 pathway. Metabolomics analysis revealed that topical application of MGO could significantly regulate tryptophan metabolism and affect the level of tryptophan in skin lesions. Tryptophan could also regulate inflammation-related genes and inhibit pyroptosis-related NLRP3/Caspase-1 pathway in LPS-stimulated PMA-differentiated THP-1 cells. In conclusion, this study suggested that topical MGO may ameliorate psoriasis-like dermatitis by inhibiting NLRP3/Caspase-1 pathway and regulating tryptophan metabolism.

Challenges in Psoriasis Research: A Systematic Review of Preclinical Models

INTRODUCTION

Psoriasis is a chronic inflammatory skin disease with variable clinical presentation, multifactorial etiology and an immunogenetic basis. Several studies demonstrate that it results from a dysregulated interaction between skin keratinocytes, immune cells, and the environment that leads to a persistent inflammatory process modulated by cytokines and T cells. The development of new treatment options requires increased understanding of pathogenesis. However, the successful implementation of effective drugs requires well-characterized and highly available preclinical models that allow researchers to quickly and reproducibly determine their safety and efficacy.

METHODS

A systematic search on PubMed and Scopus databases was performed and assessed to find appropriate articles about psoriasis models applying the key words previously defined. The PRISMA guidelines were employed.

RESULTS

A total of 45 original articles were selected that met the selection criteria. Among these, there are articles on in vivo, in vitro, and ex vivo models, with the in vitro model being the majority due to its ease of use. Within animal models, the most widely used in recent years are chemically induced models using a compound known as imiquimod. However, the rest of the animal models used throughout the disease's research were also discussed. On the other hand, in vitro models were divided into two and three dimensions. The latter were the most used due to their similarity to human skin. Lastly, the ex vivo models were discussed, although they were the least used due to their difficulty in obtaining them.

CONCLUSIONS

Therefore, this review summarizes the current preclinical models (in vivo, in vitro, and ex vivo), discussing how to develop them, their advantages, limitations, and applications. There are many challenges to improve the development of the different models. However, research in these in vitro model studies could reduce the use of animals. This is favored with the use of future technologies such as 3D bioprinting or organ-on-a-chip technologies.

Inhibition of Ca2+-permeable TRPV3 and inflammatory cytokine release by honokiol and magnolol in human epidermal keratinocytes

Transient receptor potential vanilloid-3 (TRPV3) ion channels are prominently expressed in keratinocytes, playing a vital role in skin functions. Honokiol and magnolol (H&M) the primary bioactive constituents in Magnolia officinalis extract, demonstrate anti-inflammatory and skin-protective properties. Nevertheless, the underlying mechanism regarding their effect on Ca2+-permeable ion channels remain unclear. Our purpose in this study is to investigate the effect of H&M on TRPV3 and cytokine release in normal human epidermal keratinocytes (NHEKs), including its gain-of-function (GOF) mutants (G573S and G573C) associated with Olmstead syndrome. We performed whole-cell patch-clamp, fura-2 spectrofluorimetry to investigate channels activity, CCK-8 assay to analyze cell death and enzyme-linked immunosorbent assay to assess the cytokine release from NHEKs. H&M inhibited the TRPV3 current (ITRPV3) and cytosolic calcium increase in NHEKs, HEK293T cells overexpressing hTRPV3 and its GOF mutants. Moreover, the release of pro-inflammatory cytokines (interleukin-6 and -8) from keratinocytes stimulated by TRPV3 agonist was effectively suppressed by H&M. Our findings provide insights into the mechanism underlying the anti-inflammatory effects of H&M, highlighting their potential in treating skin diseases.

Strategies to Develop a Suitable Formulation for Inflammatory Skin Disease Treatment

Skin barrier functions, environmental insults, and genetic backgrounds are intricately linked and form the basis of common inflammatory skin disorders, such as atopic dermatitis, psoriasis, and seborrheic dermatitis, which may seriously affect one’s quality of life. Topical therapy is usually the first line of management. It is believed that successful topical treatment requires pharmaceutical formulation from a sufficient dosage to exert therapeutic effects by penetrating the stratum corneum and then diffusing to the target area. However, many factors can affect this process including the physicochemical properties of the active compound, the composition of the formulation base, and the limitations and conditions of the skin barrier, especially in inflammatory skin. This article briefly reviews the available data on these issues and provides opinions on strategies to develop a suitable formulation for inflammatory skin disease treatment.