1480 CXCR4 expression by regulatory T cells promotes cutaneous tissue regeneration

Regulatory T cells (Tregs) are specialized lymphocytes that critical to preventing autoimmunity. In skin, Tregs also possess non-classical functions include promotion of hair growth and epidermal repair following superficial tissue injury. We showed a subset accumulate around follicles in murine human skin suggesting local interactions facilitate these functions. However, the chemotactic mechanisms govern Treg accumulation follicle epithelium unknown. performed single cell RNA sequencing flow cytometry, which revealed preferentially express CXCR4 mRNA protein compared effector lymph nodes. Since CXCL12 is only known cognate ligand for CXCR4, CXCL12-dsRed reporter mice were used show an enrichment this chemokine keratinocytes isthmic/infundibulum region lesser extent, bulge region. lacking demonstrated migration defect gradientin vitrosuggesting pathway utilized by trafficking skin. Constitutive deletion on did not impact cutaneous immune homeostasis. depilation, with deficiency decrease number epithelium, was associated decreased proliferation stem (HFSC), reduced length histology, significant delay regrowth clinically. Furthermore, model injury, resulted increased transepidermal water delayed barrier recovery. Taken together, results suggest CXCR4-CXCL12 axis may be necessary optimal mobilization promote regeneration through modulation HFSC biology.