Hair Follicle Mesenchyme-Associated PD-L1 Regulates T-Cell Activation Induced Apoptosis: A Potential Mechanism of Immune Privilege

September 2013 in “ Journal of Investigative Dermatology ”

Xiaojie Wang, Alexandra K. Marr, Trisia Breitkopf, Gigi Leung, Jianqiang Hao, Eddy Wang, Nicole Kwong, Noushin Akhoundsadegh, Lieping Chen, Alice Mui, Nicholas Carr, Garth L. Warnock, Jerry Shapiro, Kevin J. McElwee

hair follicle dermal papilla dermal sheath cup cells immune privilege programmed cell death 1 ligand 1 PD-L1 T-cell activation apoptosis mitochondrial pathway peripheral blood mononuclear cells T-cell PBMCs

TLDR Hair follicle cells help protect against immune attacks by regulating T-cell activity.

The study investigated the immune privilege (IP) properties of cultured hair follicle (HF) cells, specifically focusing on dermal papilla and dermal sheath cup cells (DSCCs). It was found that these cells exhibited preferential expression of IP-associated genes compared to non-follicular fibroblasts (FBs), indicating potential functional IP. A key finding was the significant upregulation of programmed cell death 1 ligand 1 (PD-L1) in DSCCs and dermal papilla cells, which played a role in reducing IFNγ secretion and increasing apoptosis in co-cultured peripheral blood mononuclear cells (PBMCs). The study demonstrated that PD-L1 expression contributed to the IP properties of DSCCs by regulating T-cell activation-induced apoptosis, primarily through the mitochondrial pathway.

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