New small molecules in dermatology: for the autoimmunity, inflammation and beyond

A tri-compound formula comprising Ginsenoside Rg1, tetrandrine and icariin alleviates atopic dermatitis symptoms in a mouse model

BACKGROUND

Atopic dermatitis (AD) is characterized by both IgE- and non-IgE-mediated immune responses, as well as skin barrier dysfunction. Ginsenoside Rg1, tetrandrine, and icariin each exhibit distinct properties that may contribute to the management of AD. Ginsenoside Rg1 has demonstrated efficacy in mitigating IgE-mediated allergic rhinitis, while tetrandrine is known to suppress abnormal T-cell activation. Icariin has been shown to improve intestinal barrier function, which is crucial in conditions like AD. However, the potential effectiveness of the combined formula of these compounds, referred to as GTI, in treating AD remains unexplored.

PURPOSE

This study aimed to investigate the anti-AD effects and mechanisms of GTI in a mouse model.

METHODS

A calcipotriol (MC903)-induced AD-like dermatitis mouse model was used to evaluate the anti-AD effects of GTI. Dermatitis scores and mouse ear thickness were recorded to assess disease severity. Ear tissues, ear-draining lymph nodes, spleens and sera were collected for use in the investigation of the effects and mechanisms of action of GTI.

RESULTS

Topical application of GTI significantly alleviated AD-like dermatitis in mice, as evidenced by decreased dermatitis scores, reduced ear thickening, and diminished epidermal and dermal thickness, along with lower levels of the inflammatory cytokines IL-1β and IL-4 in ear tissues. Unlike the positive dexamethasone, GTI had no significant toxicity in the model mice. Topical GTI lowered serum IgE levels and diminished the accumulation of eosinophils and mast cells in ear tissues of model mice, suggesting that GTI mitigates IgE-mediated allergic reactions. GTI significantly decreased the numbers of CD4+ T cells in ear tissues, ear-draining lymph nodes and the spleen, demonstrating its suppressive effect on hyperactive immune responses. The protein levels of ZO-1 and claudin-1, two tight junction proteins, were elevated in the ear tissues of mice treated with GTI, indicating a beneficial effect of this formula on skin barrier function. Additionally, GTI inhibited the activation of mitogen-activated protein kinases (MAPKs), as indicated by the downregulation of phospho-p38 (Thr180/182), phospho-ERK (Thr202/Tyr204), and phospho-JNK (Thr183/185) protein levels in mouse ear tissues.

CONCLUSION

This study, for the first time, demonstrated that the topical application of GTI alleviates symptoms of AD without overt toxicity in a calcipotriol-induced AD mouse model. The anti-AD effects of GTI are associated with the suppression of allergic reactions, reduction of hyperactive immune responses, improvement of skin barrier function, and inhibition of MAPK activation. These findings suggest that GTI has the potential to be developed into a safe and effective treatment for AD.

Prurigo: review of its pathogenesis, diagnosis, and treatment

Prurigo is a reactive, hyperplastic skin condition characterized by pruritic papules, plaques, and/or nodules. The temporal classification includes acute/subacute and chronic disease (≥ 6 weeks), with different clinical variants, synonymies, and underlying etiological factors. The immunology of chronic prurigo shows similarities with atopic dermatitis due to the involvement of IL-4 and IL-13, IL-22, and IL-31. Treatment includes antihistamines, topical steroids, dupilumab, and JAK inhibitors. Several conditions manifest clinically as prurigo-like lesions, and the correct clinical diagnosis must precede correct treatment. Furthermore, chronic prurigos represent a recalcitrant and distressing dermatosis, and at least 50% of these patients have atopic diathesis, the treatment of which may induce adverse effects, especially in the elderly. The quality of life is significantly compromised, and topical treatments are often unable to control symptoms and skin lesions. Systemic immunosuppressants, immunobiologicals, and JAK inhibitors, despite the cost and potential adverse effects, may be necessary to achieve clinical improvement and quality of life. This manuscript reviews the main types of prurigo, associated diseases, their immunological bases, diagnosis, and treatment.

Qing-Re-Chu-shi decoction ameliorates 2,4-dinitrochlorobenzene-induced atopic dermatitis in NC/Nga mice through anti-inflammation and immunoregulatory mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Qing-Re-Chu-Shi Decoction (QRCSD), a traditional Chinese herbal formula, has been employed as a complementary and alternative therapy for inflammatory skin diseases. However, its active constituents and the mechanistic basis of its action on atopic dermatitis remain in adequately understood.

AIM OF THE STUDY

Atopic dermatitis (AD) is an allergic dermatitis marked by eczematous lesions and pruritus. The study aimed to elucidate the underlying effects of QRCSD on AD and to identify the components responsible for its therapeutic efficacy in a mouse model.

MATERIALS AND METHODS

Network pharmacology and UPLC-mass analysis were used to anticipate the pharmacological mechanisms and to identify active components of QRCSD, respectively. A DNCB-induced AD-like model was established in NC/Nga mice. QRCSD or prednisolone (as a positive control) was administered via gavage every other day from day14 to day 21. Dermatitis severity score, scratching behavior, skin barrier function, spleen index, Th1/Th2 lymphocyte ratio, and serum IgE levels were evaluated. Protein arrays, including 40 inflammatory cytokines, were performed on skin lesions, followed by confirmation experiments of Western blotting in dorsal skin lesions.

RESULTS

The construction of a QRCSD-AD-Network and topological analysis firstly proposed potential targets of QRCSD acting on AD. Animal experiments demonstrated that oral administration of QRCSD ameliorated AD-like lesions, reduced epidermal thickness and mast cell count, decreased serum IgE levels, augmented tight junction protein (Claudin 1, Occludin) levels, and regulated the Th1/Th2 balance in the spleen, as well as spleen index. Elevated levels of interleukin (IL)-4, IL-5, IL-6, IL-17, and Eotaxin were revealed in AD-like skin lesions by protein arrays. Western blotting confirmed that the phosphorylation levels of ERK, P38, JNK, STAT3 and P65 were downregulated, and IL-6 expression was also reduced following QRCSD treatment.

CONCLUSIONS

The study enhances the understanding of the anti-inflammatory and immunomodulatory effects of QRCSD, showcasing its significant protective role against atopic dermatitis. Treatment with QRCSD may be considered as a viable candidate for complementary and alternative therapy in managing atopic dermatitis.