Pinus densiflora bark extract ameliorates 2,4-dinitrochlorobenzene-induced atopic dermatitis in NC/Nga mice by regulating Th1/Th2 balance and skin barrier function

Anti-Inflammatory Herbal Extracts and Their Drug Discovery Perspective in Atopic Dermatitis

Atopic dermatitis (AD) is an allergic disorder characterized by skin inflammation. It is well known that the activation of various inflammatory cells and the generation of inflammatory molecules are closely linked to the development of AD. There is accumulating evidence demonstrating the beneficial effects of herbal extracts (HEs) on the regulation of inflammatory response in both in vitro and in vivo studies of AD. This review summarizes the anti-atopic effects of HEs and its associated underlying mechanisms, with a brief introduction of in vitro and in vivo experiment models of AD based on previous and recent studies. Thus, this review confirms the utility of HEs for AD therapy.

Phenolic changes in a combined herbal extract of Lithospermum erythrorhizon, Houttuynia cordata, and Spirodela polyrhiza and alleviation of DNCB-induced atopic dermatitis in BALB/c mice

Atopic dermatitis (AD) is an inflammatory skin disease showing skin barrier dysfunction, eczematous lesions, severe itching, and abnormal immune responses. The aim of this study was to determine whether an herb combination of Lithospermum erythrorhizon (LE), Houttuynia cordata (HC), and Spirodela polyrhiza (SP) has a superior anti-AD effect. Forty-two compounds were identified in LE, HC, SP, and a combined herb extract of LE, HC, and SP (LHS) using ultra-high-pressure liquid chromatography (UHPLC)-Orbitrap mass spectrometer (MS). The concentration of flavonoid glycosides including orientin (luteolin-8-C-glucoside), quercetin-3-O-rhamnoside, and luteolin-7-O-glucoside in the LHS was increased than in individual extracts. Furthermore, the treatment of LHS most effectively inhibited the increase of epidermal thickness, the number of mast cells, and the release of immunoglobulin E compared with that with each extract. These results suggest that the potential anti-AD effects of the LHS are due to the changes of bioactive compounds by the combination of herbs.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01329-7.

Helicobacter pylori infection attenuates 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions in C57/BL6 mice

BACKGROUND

Although numerous studies have suggested a negative correlation between Helicobacter pylori (H. pylori) infection and allergies, there has been limited research on the relationship between H. pylori infections and atopic dermatitis (AD). The present study aimed to investigate the effects of H. pylori infection in an AD mouse model and identify potential mechanisms related to type 2 immunity, skin barrier defects, and pruritus.

METHODS

A model of AD-like symptoms was established with 2,4-dinitrochlorobenzene (DNCB) after infection of the gastric cavity with H. pylori. Analysis of the expression of key inflammatory cytokines and serum levels of immunoglobulin E (IgE) was based on enzyme-linked immunosorbent assay (ELISA). The expression of filaggrin (FLG) and loricrin (LOR) were analyzed by immunohistochemistry staining. The evaluation of STAT1, STAT3, phosphorylated STAT1 (phospho-STAT1), and phosphorylated STAT3 (phospho-STAT1) expression levels in skin lesions was performed using western blot.

RESULTS

The present study showed that the H. pylori-positive AD group (HP+AD+) exhibited milder skin lesions, including erythema, erosion, swelling, and scaling, than the H. pylori-negative AD group (HP-AD+). Additionally, HP+AD+ displayed lower levels of IgE in serum, and downregulated expression of interleukins 4 and 31 (IL-4 and IL-31) in serum. Furthermore, HP+AD+ demonstrated higher expression of filaggrin and loricrin than HP-AD+. Notably, H. pylori significantly reduced the amount of phosphorylated STAT1 and STAT3.

CONCLUSION

Helicobacter pylori infection negatively regulates the inflammatory response by affecting inflammatory factors in the immune response, and repairs the defective epidermal barrier function. In addition, H. pylori infection may reduce IL-31, thereby alleviating pruritus. These effects may be associated with the inhibition of JAK-STAT signaling activation.

Microbiota and IL-33/31 Axis Linkage: Implications and Therapeutic Perspectives in Atopic Dermatitis and Psoriasis

Microbiome dysbiosis and cytokine alternations are key features of atopic dermatitis (AD) and psoriasis (PsO), two of the most prevalent and burdensome pruritic skin conditions worldwide. Interleukin (IL)-33 and IL-31 have been recognized to be major players who act synergistically in the pathogenesis and maintenance of different chronic inflammatory conditions and pruritic skin disorders, including AD and PsO, and their potential role as therapeutic targets is being thoroughly investigated. The bidirectional interplay between dysbiosis and immunological changes has been extensively studied, but there is still debate regarding which of these two factors is the actual causative culprit behind the aetiopathological process that ultimately leads to AD and PsO. We conducted a literature review on the Pubmed database assessing articles of immunology, dermatology, microbiology and allergology with the aim to strengthen the hypothesis that dysbiosis is at the origin of the IL-33/IL-31 dysregulation that contributes to the pathogenesis of AD and PsO. Finally, we discussed the therapeutic options currently in development for the treatment of these skin conditions targeting IL-31, IL-33 and/or the microbiome.

Morinda officinalis extract exhibits protective effects against atopic dermatitis by regulating the MALAT1/miR-590-5p/CCR7 axis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a genetic predisposition, and the traditional Chinese medicine Morinda officinalis and its roots are characterized with anti-inflammatory effects and have been used for the treatment of various disease. However, it is still largely unknown whether Morinda officinalis extract (MOE) can be used for the treatment of AD.

OBJECTIVES

In our study we aimed to determine whether MOE could ameliorate 2,4-dinitrochlorobenzene (DNCB)-induced AD and elucidate molecular mechanisms.

METHODS

We established an AD mouse model by using DNCB. Skin pathological analysis and ELISA assay were used to detect the effect of MOE on the inflammation of AD model mouse skin and the expression changes of inflammatory factors, and further functional verification was performed in TNF-α/IFN-γ-induced HaCaT cells.

RESULTS

Our in vivo experiments confirmed that MOE remarkably reduced DNCB-induced AD lesions and symptoms, such as epidermal and dermal thickness and mast cell infiltration and inflammatory cytokines secretion in the mice models. In addition, the underlying mechanisms by which MOE ameliorated AD had been uncovered, and we verified that MOE inhibited MALAT1 expression in AD, resulting in attenuated expression of C-C chemokine receptor type 7 (CCR7) regulated by MALAT1-sponge miR-590-5p in a competing endogenous RNA (ceRNA) mechanisms-dependent manner, thereby inhibiting TNF-α/IFN-γ-induced cellular proliferation and inflammation.

Glycyrrhizic acid suppresses atopic dermatitis-like symptoms by regulating the immune balance

BACKGROUND

Glycyrrhiza is one of the most widely used traditional Chinese medicines in China. Its main bioactive ingredient glycyrrhizic acid (GA) has the potential to be used as a treatment for atopic dermatitis (AD) because it has similar actions to steroids, but with relatively few side effects.

AIMS

The objective of this study was to explore the potential mechanisms of GA on AD mice model.

METHODS

Calcipotriol, a vitamin D3 analogue (MC903) was applied topically to establish AD mouse model. Mice were intraperitoneally administrated with 2 mg/kg dexamethasone (DEX), 25 or 50 mg/kg GA for 15 days. After mice were executed, skin tissues were collected and detected the expression levels of IL-4, IFN-γ, TNF-α and thymic stromal lymphopoietin (TSLP). The percentages of Th1, Th2, Th17, langerhans cells (LCs) in draining lymph nodes (dLNs) were measured by flow cytometry.

RESULTS

Our data demonstrated that GA improved the symptoms of AD by exerting anti-inflammatory and anti-allergic functions in vivo. We found that GA treatment decreased the level of total IgE in serum, suppressed ear swelling, reduced the infiltration of mast cells in skin lesions and decreased expressions of IL-4, IFN-γ, TNF-α and TSLP in skin lesions. Furthermore, our experimental results demonstrated that GA suppressed the Th1/Th2/Th17-immune responses in the dLNs, inhibited the migration of LCs in dLNs.

CONCLUSIONS

In conclusion, our findings suggested potential therapeutic effects of GA against MC903-induced AD-like skin lesions in mice.

IL-31: State of the Art for an Inflammation-Oriented Interleukin

Interleukin 31 belongs to the IL-6 superfamily, and it is an itch mediator already studied in several diseases, comprising atopic dermatitis, allergic pathologies, and onco-hematological conditions. This research aims to assess the role of this cytokine in the pathogenesis of these conditions and its potential therapeutic role. The research has been conducted on articles, excluding reviews and meta-analysis, both on animals and humans. The results showed that IL-31 plays a crucial role in the pathogenesis of systemic skin manifestations, prognosis, and itch severity. Traditional therapies target this interleukin indirectly, but monoclonal antibodies (Mab) directed against it have shown efficacy and safety profiles comparable with biological drugs that are already available. Future perspectives could include the development of new antibodies against IL-31 both for humans and animals, thus adding a new approach to the therapy, which often has proven to be prolonged and specific for each patient.

Deacetylasperulosidic Acid Ameliorates Pruritus, Immune Imbalance, and Skin Barrier Dysfunction in 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis NC/Nga Mice

The prevalence of atopic dermatitis (AD), a disease characterized by severe pruritus, immune imbalance, and skin barrier dysfunction, is rapidly increasing worldwide. Deacetylasperulosidic acid (DAA) has anti-atopic activity in the three main cell types associated with AD: keratinocytes, mast cells, and eosinophils. Our study investigated the anti-atopic activity of DAA in 2,4-dinitrochlorobenzene-induced NC/Nga mice. DAA alleviated the symptoms of AD, including infiltration of inflammatory cells (mast cells and eosinophils), epidermal thickness, ear thickness, and scratching behavior. Furthermore, DAA reduced serum IgE, histamine, and IgG1/IgG2a ratio and modulated the levels of AD-related cytokines and chemokines, namely interleukin (IL)-1β, IL-4, IL-6, IL-9, IL-10, IL-12, tumor necrosis factor-α, interferon-γ, thymic stromal lymphopoietin, thymus and activation-regulated chemokine, macrophage-derived chemokine, and regulated on activation the normal T cell expressed and secreted in the serum. DAA restored immune balance by regulating gene expression and secretion of Th1-, Th2-, Th9-, Th17-, and Th22-mediated inflammatory factors in the dorsal skin and splenocytes and restored skin barrier function by increasing the expression of the pro-filaggrin gene and barrier-related proteins filaggrin, involucrin, and loricrin. These results suggest DAA as a potential therapeutic agent that can alleviate the symptoms of AD by reducing pruritus, modulating immune imbalance, and restoring skin barrier function.

Anti-Allergic and Anti-Inflammatory Effects of Neferine on RBL-2H3 Cells

Mast cells play a very important role in skin allergy and inflammation, including atopic dermatitis and psoriasis. In the past, it was found that neferine has anti-inflammatory and anti-aging effects on the skin, but its effect on mast cells has not yet been studied in detail. In this study, we used mast cells (RBL-2H3 cells) and mouse models to study the anti-allergic and inflammatory effects of neferine. First, we found that neferine inhibits the degranulation of mast cells and the expression of cytokines. In addition, we observed that when mast cells were stimulated by A23187/phorbol 12-myristate-13-acetate (PMA), the elevation of intracellular calcium was inhibited by neferine. The phosphorylation of the MAPK/NF-κB pathway is also reduced by pretreatment of neferine. The results of in vivo studies show that neferine can improve the appearance of dermatitis and mast cell infiltration caused by dinitrochlorobenzene (DNCB). Moreover, the expressions of barrier proteins in the skin are also restored. Finally, it was found that neferine can reduce the scratching behavior caused by compound 48/80. Taken together, our results indicate that neferine is a very good anti-allergic and anti-inflammatory natural product. Its effect on mast cells contributes to its pharmacological mechanism.

Lithospermum erythrorhizon Alleviates Atopic Dermatitis-like Skin Lesions by Restoring Immune Balance and Skin Barrier Function in 2.4-Dinitrochlorobenzene-Induced NC/Nga Mice

The incidence of atopic dermatitis (AD), a disease characterized by an abnormal immune balance and skin barrier function, has increased rapidly in developed countries. This study investigated the anti-atopic effect of Lithospermum erythrorhizon (LE) using NC/Nga mice induced by 2,4-dinitrochlorobenzene. LE reduced AD clinical symptoms, including inflammatory cell infiltration, epidermal thickness, ear thickness, and scratching behavior, in the mice. Additionally, LE reduced serum IgE and histamine levels, and restored the T helper (Th) 1/Th2 immune balance through regulation of the IgG1/IgG2a ratio. LE also reduced the levels of AD-related cytokines and chemokines, including interleukin (IL)-1β, IL-4, IL-6, tumor necrosis factor-α (TNF-α), thymic stromal lymphopoietin, thymus and activation-regulated chemokine, macrophage-derived chemokine, regulated on activation, normal T cell expressed and secreted, and monocyte chemoattractant protein-1 in the serum. Moreover, LE modulated AD-related cytokines and chemokines expressed and secreted by Th1, Th2, Th17, and Th22 cells in the dorsal skin and splenocytes. Furthermore, LE restored skin barrier function by increasing pro-filaggrin gene expression and levels of skin barrier-related proteins filaggrin, involucrin, loricrin, occludin, and zonula occludens-1. These results suggest that LE is a potential therapeutic agent that can alleviate AD by modulating Th1/Th2 immune balance and restoring skin barrier function.

Effects of Deacetylasperulosidic Acid on Atopic Dermatitis through Modulating Immune Balance and Skin Barrier Function in HaCaT, HMC-1, and EOL-1 Cells

The medicinal plant noni (Morinda citrifolia) is widely dispersed throughout Southeast Asia, the Caribbean, and Australia. We previously reported that fermented Noni could alleviate atopic dermatitis (AD) by recovering Th1/Th2 immune balance and enhancing skin barrier function induced by 2,4-dinitrochlorobenzene. Noni has a high deacetylasperulosidic acid (DAA) content, whose concentration further increased in fermented noni as an iridoid constituent. This study aimed to determine the anti-AD effects and mechanisms of DAA on HaCaT, HMC-1, and EOL-1 cells. DAA inhibited the gene expression and secretion of AD-related cytokines and chemokines including interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-25, IL-33, thymic stromal lymphopoietin, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, thymus and activation-regulated chemokine, macrophage-derived chemokine, and regulated upon activation, normal T cell expressed and secreted, in all cells, and inhibited histamine release in HMC-1 cells. DAA controlled mitogen-activated protein kinase phosphorylation levels and the translocation of nuclear factor-kappa light chain enhancer of activated B cells into the nucleus by inhibiting IκBα decomposition in all the cells. Furthermore, DAA increased the expression of proteins involved in skin barrier functions such as filaggrin and involucrin in HaCaT cells. These results confirmed that DAA could relieve AD by controlling immune balance and recovering skin barrier function.

Ameliorative effects of total coumarins from the fructus of Cnidium monnieri (L.) Cuss. on 2,4-dinitrochlorobenzene-induced atopic dermatitis in rats

Atopic dermatitis (AD), which is characterized by intense pruritus and serious inflammation, is a chronic skin disease. Modern studies have testified that the total coumarins from the fructus of Cnidium monnieri (TCFC) possess evident biological activities based on their coumarin compounds. The purpose of this manuscript is to investigate the effects of topical use of TCFC on immune response, inflammation, and skin barrier function in rats with 2,4-dinitrochlorobenzene (DNCB)-induced AD. Results indicated that the skin lesion scores of rats were obviously reduced after the management of TCFC, and the spleen and thymus indices also were markedly repressed. TCFC significantly inhibited the overproduction of TNF-α, interferon-γ, interleukin (IL)-4, IL-13, thymic stromal lymphopoietin, and immunoglobulin E; the epidermal thickness and number of mast cells were notably decreased. The western blot experiment was conducted to determine the effects of TCFC on the mitogen-activated protein kinases signaling pathway. Results indicated that phosphorylation of extracellular signal-regulated kinases, p38, and c-Jun amino-terminal kinases was significantly blocked by TCFC. In addition, TCFC could upregulate the expression of filaggrin in dorsal skin, which means that TCFC showed a protective effect on skin barrier disruption. Furthermore, TCFC downregulated the levels of IL-1β, IL-4, IL-31, and TSLP mRNA and upregulated the expression of filaggrin mRNA in the dorsal skin of rats. Our research demonstrated the ameliorative effects of TCFC on AD-like rats by inhibiting immune response and inflammation and recovering skin barrier function.

Compound K improves skin barrier function by increasing SPINK5 expression

Background

The skin acts as a barrier to protect organisms against harmful exogenous agents. Compound K (CK) is an active metabolite of ginsenoside Rb1, Rb2 and Rc, and researchers have focused on its skin protective efficacy. In this study, we hypothesized that increased expression of the serine protease inhibitor Kazal type-5 (SPINK5) may improve skin barrier function.

Methods

We screened several ginsenosides to increase SPINK5 gene promoter activity using a transactivation assay and found that CK can increase SPINK5 expression. To investigate the protective effect of CK on the skin barrier, RT-PCR and Western blotting were performed to investigate the expression levels of SPINK5, kallikrein 5 (KLK5), KLK7 and PAR2 in UVB-irradiated HaCaT cells. Measurement of transepidermal water loss (TEWL) and histological changes associated with the skin barrier were performed in a UVB-irradiated mouse model and a 1-chloro-2,4-dinitrobenzene (DNCB)-induced atopic dermatitis-like model.

Results

CK treatment increased the expression of SPINK5 and decreased the expression of its downstream genes, such as KLKs and PAR2. In the UVB-irradiated mouse model and the DNCB-induced atopic dermatitis model, CK restored increased TEWL and decreased hydration and epidermal hyperplasia. In addition, CK normalized the reduced SPINK5 expression caused by UVB or DNCB, thereby restoring the expression of the proteins involved in desquamation to a level similar to normal.

Conclusions

Our data showed that CK contributes to improving skin-barrier function in UVB-irradiated and DNCB-induced atopic dermatitis-like models through SPINK5. These results suggest that therapeutic attempts with CK might be useful in treating barrier-disrupted diseases.

Pediococcus acidilactici intake decreases the clinical severity of atopic dermatitis along with increasing mucin production and improving the gut microbiome in Nc/Nga mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is associated with intestinal microflora. Since specific probiotics may have better efficacy for AD, we determined the efficacy of Pediococcus acidilactici SRCM102024 (PA) for treating AD in HaCaT cells and NC/Nga mice and explored the mechanism of action. AD-like pathology was induced in HaCaT cells and the dorsal skin of Nc/Nga mice by local exposure to 2,4-dinitrochlorobenzene (DNCB). In AD-lesion induced mice, PA in low-, medium- and high-dosages (5 × 10E6, 5 × 10E7 and 5 × 10E8 CFU/kg bw, respectively) and dexamethasone (3 mg/kg bw, positive-control) were orally administered for 5 weeks. The clinical AD severity, serum immunoglobulin E (IgE) and TNF-α, gene expressions of interleukin (IL)-4, IL-13, and TNF-α and gut microflora were measured. PA treatment (100-300 CFU/mL) dose-dependently increased cell survival in DNCB-induced HACAT cells. PA reduced the relative mRNA expression of PAR-2, TNF-α, IL-4 and IL-13 in the cells. In dorsal skin of Nc/Nga mice applied with DNCB, PA dose-dependently attenuated erythema, hemorrhage, edema, excoriation, dryness and scratching behavior and PA-H improved the clinical symptoms similar to the positive-control. PA-M and PA-H treatment significantly prevented the disturbance of the dorsal skin tissues and decreased the inflammatory cellular infiltrate of mast cells, compared to the control. PA dose-dependently reduced serum IgE and TNF-α concentrations and the mRNA expression of TNF-α, IL-4, and IL-13 in dorsal skin. In gut microflora, relative counts of Lactobacillales, Butyricicoccus and Ruminococcus were decreased in the AD-control compared to the positive-control and the PA-M and PA-H prevented their decrease. However, the positive-control increased serum AST and ALT activities, indicating liver damage as an adverse effect. In conclusion, oral treatment of PA (human equivalent 1 × 10E9-1 × 10E10) relieved the AD symptoms by dose-dependently preventing over-activation of the immune response. Oral PA intake may be a safe and effective alternative therapy for AD.

Fermented Morinda citrifolia (Noni) Alleviates DNCB-Induced Atopic Dermatitis in NC/Nga Mice through Modulating Immune Balance and Skin Barrier Function

Morinda citrifolia, a fruit generally known as "Noni", has been traditionally used in parts of East Asia to relieve inflammatory diseases. Although several studies using noni have been reported, the effect of fermented Morinda citrifolia (F.NONI) on atopic dermatitis (AD) has not been investigated. Thus, we aimed to investigate the improving effect of F.NONI treatment on AD-like skin lesions and elucidate molecular mechanisms. F.NONI was prepared by the fermentation of noni fruit with probiotics and then extracted. F.NONI was orally administrated to NC/Nga mice to evaluate its therapeutic effect on 2,4-dinitrochlorobenzene (DNCB)-induced AD. Oral administration of F.NONI significantly alleviated AD lesions and symptoms such as dermatitis scores, ear thickness, scratching behavior, epidermal thickness, and infiltration of inflammatory cells (e.g., mast cells and eosinophils). In addition, F.NONI treatment reduced the levels of histamine, IgE and IgG1/IgG2a ratio, thymus and activation regulated chemokine (TARC), and thymic stromal lymphopoietin (TSLP) in serum and beneficially modulated the expressions of Th1, Th2, Th17, and Th22-mediated cytokines in lesioned skin and splenocytes. Furthermore, the expressions of the skin barrier-related proteins including filaggrin (FLG), loricrin (LOR), involucrin (IVL), zonula occludens-1 (ZO-1), and occludin (OCC) were restored by F.NONI treatment. Taken together, these results suggest that F.NONI could be a therapeutic agent to attenuate AD-like skin lesions through modulating the immune balance and skin barrier function.