Related Experiment Video
Updated: Jun 25, 2026

A Rat Model of Compound Acne
Published on: November 1, 2024
Commensal Cutibacterium acnes-derived indolelactic acid safeguards skin barrier function through the aryl hydrocarbon
Shan Zhang1, Fang Li2, Xiaoqiang Xu3
1Department of Allergy and Rheumatology, Jiangsu Provincial Key Laboratory of Dermatology, Hospital for Skin Diseases, Institute of Dermatology, Chinese Academy of Medical Sciences & Peking Union Medical College, Nanjing 210042, China; Department of Dermatology, Children's Hospital of Nanjing Medical University, Nanjing 210008, Jiangsu, China.
Abstract:
Skin microbial dysbiosis is a key characteristic of atopic dermatitis (AD). Although Cutibacterium acnes (C. acnes) is the most abundant bacterium in the skin microbiota, its precise functions in AD remain unclear. Here, whole-genome sequencing of C. acnes isolates reveals strain-level genomic and functional heterogeneity between AD patients and healthy individuals. Metabolomic profiling identifies reduced indolelactic acid (ILA), a tryptophan metabolite, in AD skin and in cultures of AD-associated C. acnes strains. In murine models of epidermal-barrier-damaged and AD-like dermatitis, topical ILA application activates the aryl hydrocarbon receptor (AhR) pathway in keratinocytes, upregulating tight junction proteins and suppressing interleukin (IL)-33 to restore barrier integrity and mitigate dermatitis. A proof-of-concept clinical trial confirms ILA's efficacy in reducing transepidermal water loss and alleviating AD symptoms. Our study establishes C. acnes-derived ILA as a crucial regulator of skin barrier repair via AhR signaling, offering therapeutic potential for AD. Clinical trial registration: ChiCTR2400090988.
Related Concept Videos
The Skin Microbiota
Acne Infection
Defense Mechanism Against Infection
In addition, many body organ systems have unique defenses against infection. The skin is an intact, multilayered surface preventing invasion by microorganisms unless impaired. Mucous membranes lining the mouth, nose, and eyelids are barriers...
Surface Membrane Barriers
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...
Gene Regulation in Microbial Communities: Quorum Sensing
Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
