A combination of Olea europaea leaf extract and Spirodela polyrhiza extract alleviates atopic dermatitis by modulating immune balance and skin barrier function in a 1-chloro-2,4-dinitrobenzene-induced murine model

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.

Anti-atopic dermatitis effect of fish collagen on house dust mite-induced mice and HaCaT keratinocytes

Collagen, a major structural protein in mammalian tissues, is effective against skin wounds and osteoarthritis. Although bovine and porcine collagens have mainly been used, several potential risks of mammalian collagen have led to the use of fish collagen (FC) as an alternative. FC and its peptides are used as common cosmeceutical products because of their antihypertensive, anti-bacterial, and antioxidant activities. Despite the effects of FC on wrinkle reduction, UV-protection, and wound healing, the relationship between FC and atopic dermatitis (AD) has not yet been reported. Therefore, we investigated the anti-AD effects of FC against house dust mite (Dermatophagoides farinae, HDM)-induced AD in NC/Nga mice and TNF-α/IFN-γ-stimulated HaCaT keratinocytes. FC alleviated AD apparent symptoms, such as dermatitis score, transepidermal water loss, epidermal thickness, and mast cell infiltration upon declining pro-inflammatory cytokines and mediators, IL-6, IL-5, IL-13, TSLP, and TNF-α. The skin barrier protein, filaggrin, was also recovered by FC administration in vivo and in vitro. Immune response and skin barrier dysfunction are both mitigated by three routes of FC administration: oral, topical, and both routes via the regulation of IκB, MAPKs, and STATs pathways. In summary, FC could be a potential therapeutic agent for AD by regulating immune balance and skin barrier function.

Fructo-oligofructose ameliorates 2,4-dinitrofluorobenzene-induced atopic dermatitis-like skin lesions and psychiatric comorbidities in mice

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by pruritus and eczema lesions and psychiatric comorbidities. The gut-brain-skin axis plays a pivotal role during AD development, which might suggest a novel therapeutic strategy for AD. The present study aims to uncover the protective effects and underlying mechanisms of fructo-oligofructose (FOS), a type of prebiotic, on AD-like skin manifestations and comorbid anxiety and depression in AD mice.

RESULTS

Female Kunming mice were treated topically with 2,4-dinitrofluorobenzene (DNFB) to induce AD-like symptoms and FOS was administered daily for 14 days. The results showed that FOS could alleviate AD-like skin lesions markedly as evidenced by dramatic decreases in severity score, scratching bouts, the levels of immunoglobulin E (IgE) and T helper 1(Th1)/Th2-related cytokines, and the infiltration of inflammatory cells and mast cells to the dermal tissues. The comorbid anxiety and depressive-like behaviors, estimated by the forced swimming test (FST), the tail-suspension test (TST), the open-field test (OFT), and the zero maze test (ZMT) in AD mice, were significantly attenuated by FOS. Fructo-oligofructose significantly upregulated brain neurotransmitters levels of 5-hydroxytryptamine (5-HT) and dopamine (DA). Furthermore, FOS treatment increased the relative abundance of gut microbiota, such as Prevotella and Lactobacillus and the concentrations of short-chain fatty acids (SCFAs), especially acetate and iso-butyrate in the feces of AD mice. The correlation analysis indicated that the reshaped gut microbiome composition and enhanced SCFAs formation are associated with skin inflammation and behavioral alteration.

CONCLUSION

Collectively, these data identify FOS as a promising microbiota-targeted treatment for AD-like skin inflammation and comorbid anxiety and depressive-like behaviors. © 2023 Society of Chemical Industry.

Veronica persica Ethanol Extract Ameliorates Dinitrochlorobenzene-Induced Atopic Dermatitis-like Skin Inflammation in Mice, Likely by Inducing Nrf2/HO-1 Signaling

Atopic dermatitis (AD) is chronic allergic contact dermatitis with immune dysregulation. Veronica persica has pharmacological activity that prevents asthmatic inflammation by ameliorating inflammatory cell activation. However, the potential effects of the ethanol extract of V. persica (EEVP) on AD remain elusive. This study evaluated the activity and underlying molecular pathway of EEVP in two AD models: dinitrochlorobenzene (DNCB)-induced mice and interferon (IFN)-γ/tumor necrosis factor (TNF)-α-stimulated human HaCaT keratinocytes. EEVP attenuated the DNCB-induced increase in serum immunoglobulin E and histamine levels, mast cell counts in toluidine-blue-stained dorsal skin, inflammatory cytokine (IFN-γ, interleukin [IL]-4, IL-5, and IL-13) levels in cultured splenocytes, and the mRNA expression of IL6, IL13, IL31 receptor, CCR-3, and TNFα in dorsal tissue. Additionally, EEVP inhibited the IFN-γ/TNF-α-induced mRNA expression of IL6, IL13, and CXCL10 in HaCaT cells. Furthermore, EEVP restored the IFN-γ/TNF-α-induced downregulation of heme oxygenase (HO)-1 in HaCaT cells by inducing nuclear factor erythroid 2-related factor 2 (Nrf2) expression. A molecular docking analysis demonstrated that EEVP components have a strong affinity to the Kelch-like ECH-associated protein 1 Kelch domain. In summary, EEVP inhibits inflammatory AD by attenuating immune cell activation and inducing the Nrf2/HO-1 signaling pathway in skin keratinocytes.

The Role of Tight Junctions in Atopic Dermatitis: A Systematic Review

BACKGROUND

Tight junctions are transmembrane proteins that regulate the permeability of water, solutes including ions, and water-soluble molecules. The objective of this systematic review is to focus on the current knowledge regarding the role of tight junctions in atopic dermatitis and the possible impact on their therapeutic potential.

METHODS

A literature search was performed in PubMed, Google Scholar, and Cochrane library between 2009 and 2022. After evaluation of the literature and taking into consideration their content, 55 articles were finally included.

RESULTS

TJs' role in atopic dermatitis extends from a microscopic scale to having macroscopic effects, such as increased susceptibility to pathogens and infections and worsening of atopic dermatitis features. Impaired TJ barrier function and skin permeability in AD lesions is correlated with cldn-1 levels. Th2 inflammation inhibits the expression of cldn-1 and cldn-23. Scratching has also been reported to decrease cldn-1 expression. Dysfunctional TJs' interaction with Langerhans cells could increase allergen penetration. Susceptibility to cutaneous infections in AD patients could also be affected by TJ cohesion.

CONCLUSIONS

Dysfunction of TJs and their components, especially claudins, have a significant role in the pathogenesis and vicious circle of inflammation in AD. Discovering more basic science data regarding TJ functionality may be the key for the use of specific/targeted therapies in order to improve epidermal barrier function in AD.

Total flavonoids of sea buckthorn (Hippophae rhamnoides L.) improve MC903-induced atopic dermatitis-like lesions

ETHNOPHARMACOLOGICAL RELEVANCE

Sea buckthorn (Hippophae rhamnoides L.) is popularly used as a herbal medicine and food additive in the world. Total flavonoids of Hippophae rhamnoides (TFH) are reported to have anti-inflammatory and immunomodulatory activities.

AIM

The effects of TFH on atopic dermatitis (AD)-like lesions induced by MC903 in mice was elucidated in the study.

METHODS

To induce AD-like lesions, MC903 was adopted to apply repeatedly on the left ear in C57BL/6 mice. After induction of AD-like lesions, 0.5% and 1% TFH cream was applied topically on ears of mice once a day for 8 days. The degree of skin lesions was evaluated by macroscopical and histological methods. Expressions of filaggrin (FLG) was evaluated by Western blotting. Real-time polymerase chain reaction (qPCR) was adopted to detect the mRNA expression of thymic stromal lymphopoietin (TSLP), interferon (IFN)-γ, interleukin (IL-4), tumor necrosis factor (TNF)-α in skin lesions. In vitro, Cytokine Antibody Arrays were performed to measure production of cytokines in IFN-γ/TNF-α-treated HaCaT cells, Western blotting was employed to detect the expressions of p-NF-κB, p-ERK and p-P38.

RESULTS

Topical application of TFH significantly improved the severity of dermatitis by inhibiting the infiltration of mast cell, increasing expression of FLG, decreasing the expressions of TNF-α, IL-4, IFN-γ and TSLP in skin lesions. TFH decreased the levels of IL-1α, IL-1β, IL-6, monocyte chemoattractant protein (MCP)-1, MCP-3, macrophage-derived chemokine (MDC), platelet-derived growth factor (PDGF)-BB, thymus and activation regulated chemokine (TARC) in the supernatants of the HaCaT cells treated by IFN-γ/TNF-α. Furthermore, expressions of p-NF-κB, p-ERK and p-P38 were also decreased by TFH administration with dose dependent manner in HaCaT cells treated by IFN-γ/TNF-α.

CONCLUSIONS

Topical application of TFH improved AD-like lesions in mice induced by MC903. Which exerted the effects of anti-inflammation and repairing skin barrier by regulating Th1/Th2 balance. This finding indicates that TFH is a novel potential agent for the external treatment of AD.

Different molecular weight hyaluronic acid alleviates inflammation response in DNFB-induced mice atopic dermatitis and LPS-induced RAW 264.7 cells

AIMS

Atopic dermatitis (AD) is an inflammatory chronic disease which severely interferes the life of patients. Hence, there is a great need for new therapies. Hyaluronic acid (HA) is an effective potential inflammation modifier; however, there is limited information about their implementation in inflammation therapies. This study aimed to evaluate the anti-inflammatory activities of HA and the influence of its molecular weight.

MAIN METHODS

Male C57BL/6 J mice were stimulated by 2,4-dinitrofluorobenzene to induce AD-like symptoms and immune response. The skin lesions and histopathological change, as well as levels of inflammatory factors were evaluated. RAW 264.7 mouse macrophages were treated with lipopolysaccharides (LPS) to induce inflammation. NO, IL-6, and TNF-α levels were detected through ELISA kits.

KEY FINDINGS

DNFB challenge induced mice AD symptoms including epidermal thickening, mast cell infiltration, Th2/Th1 immune response, skin lesions IL-4 and IFN-γ, and serum IgE elevation. HA treatment ameliorated such symptoms through the inhibition of PI3K/Akt signaling pathway. LPS induction stimulated the secretion of NO, IL-6, and TNF-α in RAW 264.7 cells, while HA pre-treatment reduced the concentration of the cytokines in cell supernatants.

SIGNIFICANCE

These findings give clear insight into the interaction between HA and inflammatory response, which can help guiding the utilization of HA in the AD therapies.

Compound traditional Chinese medicine dermatitis ointment ameliorates inflammatory responses and dysregulation of itch-related molecules in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease accompanied with itchy and scaly rash. Compound traditional Chinese medicine dermatitis ointment (CTCMDO) consists of a mixture of extracts from five plants, which had been used in AD treatment due to good anti-inflammatory and anti-allergic effects.

MATERIALS AND METHODS

In this study, high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometer (LC/MS) were performed to analyze the active ingredients of CTCMDO in detail and to establish its HPLC fingerprint. Furthermore, the anti-inflammatory and antipruritic activities of CTCMDO were studied in the treatment of DNCB-induced AD in mice.

RESULTS

A total of 44 compounds including phenylpropionic acid compounds, alkaloid compounds, curcumin compounds and lignans were identified via combined HPLC and LC/MS. A fingerprint with 17 common peaks was established. In AD-like mice, DNCB-induced scratching behavior had been suppressed in the treatment of CTCMDO in a dose-dependent manner. Furthermore, the detailed experimental results indicated that the AD can be effectively improved via inhibiting the production of Th1/2 cytokines in serum, reversing the upregulation of substance P levels of itch-related genes in the skin, and suppressing the phosphorylation of JNK, ERK, and p38 in the skin.

CONCLUSION

This work indicated that CTCMDO can significantly improve AD via attenuating the pathological alterations of Th1/2 cytokines and itch-related mediators, as well as inhibiting the phosphorylation of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB).