Microbes stimulate hair follicles

Area of Science:

• Immunology
• Microbiology
• Dermatology

Background:

• The skin microbiome plays a critical role in immune system development.
• Neonatal skin is a unique environment where immune tolerance is established.
• Regulatory T cells (Tregs) are essential for immune homeostasis and preventing autoimmunity.

Purpose of the Study:

• To investigate the interaction between commensal microbes and the hair follicle in immune cell recruitment.
• To identify the molecular mechanisms by which microbes influence Treg migration to neonatal skin.

Main Methods:

• Utilized mouse models of neonatal skin colonization with commensal bacteria.
• Employed techniques such as immunohistochemistry and flow cytometry to analyze immune cell populations.
• Investigated chemokine expression in hair follicles using quantitative PCR and Western blotting.

Main Results:

• Commensal microbial colonization induced significant upregulation of a specific chemokine (CXCL16) in hair follicles.
• Increased CXCL16 levels correlated with a higher infiltration of regulatory T cells into the neonatal dermis.
• Depletion of CXCL16 or its receptor (CXCR6) abrogated the microbial-induced Treg recruitment.

Conclusions:

• Commensal microbes actively instruct hair follicles to produce chemokines, thereby shaping the neonatal skin immune microenvironment.
• This hair follicle-mediated chemokine production is a key mechanism for recruiting regulatory T cells to the skin.
• These findings highlight a novel pathway for microbial-immune interaction in early life, crucial for immune tolerance development.