A topical Chinese herbal inhibits pruritus and skin inflammation via neural TRPM8 in atopic dermatitis

Author links open overlay panelYao Chen ^a†, Ziyuan Tang ^a†, Zhiyao Han ^a, Mingyang Wang ^a, Xinran Li ^a, Luying Lai ^a, Pingzheng Zhou ^a,b, Fang Wang ^c,d, Fengxian Li ^a,e,**,‡

^aDepartment of Anesthesiology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
^bGuangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
^cDepartment of Dermatology, Dermatology Hospital, Southern Medical University, Guangzhou, China
^dGuangdong Provincial Key Laboratory of Brain Function and Disease, Guangzhou, China
^eKey Laboratory of Mental Health of the Ministry of Education, Guangdong Province Key Laboratory of Psychiatric Disorders, Southern Medical University, Guangzhou, China

Received 7 September 2024, Revised 12 February 2025, Accepted 15 February 2025, Available online 16 February 2025, Version of Record 21 February 2025.

Abstract

Background

Atopic dermatitis (AD) is a chronic, itchy, and inflammatory skin disease. The neuroimmune concept of itch involves aberrant immune responses and neural activities. Chinese herbal medicine has been demonstrated to alleviate AD symptoms, but the underlying mechanisms remain not fully understand.

Purpose

Chushizhiyang (CS) ointment is a topical treatment consisting of Chinese herbal ingredients. We aimed to study the underlying mechanism of CS on treating AD.

Method

To investigate the therapeutic efficacy of CS, we utilized a well-established atopic dermatitis mouse model, administering CS ointment topically to the ears. To unravel the underlying mechanisms, we employed a multifaceted approach, including behavioral assay, network pharmacology analysis, RNA-sequencing analysis, neural tracing, and calcium imaging. Additionally, transient receptor potential (TRP) M8-deficient mice were employed to validate the specific targets of CS.

Results

By employing a murine model of AD-like disease, we found that CS ointment can reduce skin inflammation and inhibit scratching behavior. Importantly, its capacity to alleviate itch-induced scratching surpasses that of topical steroid, a positive control treatment. The RNA-sequencing analysis of the affected skin revealed that the differentially expressed genes were enriched in neuroactive pathways that include ion channels particularly TRPM8. Calcium imaging demonstrated that CS ointment is capable of activating TRPM8-positive sensory neurons. Using transgenic animals, we found that CS ointment exhibited its anti-inflammatory or anti-pruritic effects only when TRPM8 is functional intact. Additionally, CS treatment reduced neuronal activities in wild-type, rather than TRPM8-compromised animals.

Conclusion

Our findings suggest that topical Chinese herbals participate in neuroimmune mechanisms for AD-like disease via TRPM8.

Keywords

Atopic dermatitis, TRPM8, Pruritus, Inflammation, Chinese herb

Abbreviations

AD, atopic dermatitis; TRPM8, transient receptor potential M8; CS, Chushizhiyang ointment; EtOH, ethanol; HPLC, high performance liquid chromatography; TCMSP, traditional Chinese medicine systems pharmacology database; PPI, protein-protein interaction; GO, Gene Ontology; KEGG, Kyoto Encyclopedia of Genes and Genomes; IL-4, interleukin-4; IL-13, interleukin-13, IL-31, interleukin-31; IL-33, interleukin-33; CCL17, C-C Motif Chemokine Ligand 17; TSLP, thymic stromal lymphopoietin; eGFP, enhanced greed fluorescence protein; FG, fluoro-gold; DRG, dorsal root ganglion; TG, trigeminal ganglion; pERK, phosphorylated extracellular signal-regulated kinase;