Youhei Uchida1, Jennifer Gherardini2, Andreas Schulte-Mecklenbeck3, Majid Alam4, Jérémy Chéret5, Alfredo Rossi6, Takuro Kanekura1, Catharina C Gross3, Akiko Arakawa7, Amos Gilhar8, Marta Bertolini9, Ralf Paus10. 1. Department of Dermatology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan. 2. Monasterium Laboratory, Skin and Hair Research Solutions GmbH, Münster, Germany; Dr. Phillip Frost Dept. of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA. 3. Department of Neurology & Institute of Translational Neurology, University Hospital Münster, Münster, Germany. 4. Department of Dermatology & Venereology, Hamad Medical Corporation & Translational Research Institute, Academic Health System, Doha, Qatar. 5. Dr. Phillip Frost Dept. of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA. 6. Department of Clinical Internal, Anesthesiological and Cardiovascular Sciences, University "La Sapienza'', Rome, Italy. 7. Department of Dermatology, University of Munich (LMU), Munich, Germany. 8. Skin Research Laboratory, Technion-Israel Institute of Technology, Haifa, Israel. 9. Monasterium Laboratory, Skin and Hair Research Solutions GmbH, Münster, Germany. 10. Monasterium Laboratory, Skin and Hair Research Solutions GmbH, Münster, Germany; Dr. Phillip Frost Dept. of Dermatology & Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA; Centre for Dermatology Research, University of Manchester, MAHSC, and Manchester NIHR Biomedical Research Centre, Manchester, UK. Electronic address: rxp803@med.miami.edu.
Abstract
BACKGROUND: It is widely accepted that NKG2D+cells are critically involved in alopecia areata (AA) pathogenesis. However, besides being expressed in CD8+T-cells and NK cells, NKG2D is also found in human γδT-cells. AA lesional hair follicles (HFs) overexpress NKG2D and γδTCR activating ligands, e.g. MICA and CD1d, and chemoattractants for γδT-cells, such as CXCL10. OBJECTIVE: To investigate whether abnormal activities of γδT-cells may be involved in AA pathogenesis. METHODS: We analyzed the number and activation status of γδT-cells in human healthy, lesional and non-lesional AA scalp biopsies by FACS and/or quantitative (immuno-)histomorphometry. RESULTS: In healthy human scalp skin, the few skin-resident γδT-cells were found to be mostly Vδ1+, non-activated (CD69-NKG2Ddim) and positive for CXCL10, and CXCL12 receptors. These Vδ1+T-cells predominantly localized in/around the HF infundibulum. In striking contrast, the number of Vδ1+T-cells was significantly higher around and even inside the proximal (suprabulbar and bulbar) epithelium of lesional AA HFs. These cells also showed a pro-inflammatory phenotype, i.e. higher NKG2D, and IFN-γ and lower CD200R expression. Importantly, more pro-inflammatory Vδ1+T-cells were seen also around non-lesional AA HFs. Lesional AA HFs also showed significantly higher expression of CXCL12. CONCLUSION: Our pilot study introduces skin-resident γδT-cells as a previously overlooked, but potentially important, mostly (auto-)antigen-independent, new innate immunity protagonist in AA pathobiology. The HF infiltration of these activated, IFN-γ-releasing cells already around non-lesional AA HFs suggest that Vδ1+T-cells are involved in the early stages of human AA pathobiology, and may thus deserve therapeutic targeting for optimal AA management.
BACKGROUND: It is widely accepted that NKG2D+cells are critically involved in alopecia areata (AA) pathogenesis. However, besides being expressed in CD8+T-cells and NK cells, NKG2D is also found in human γδT-cells. AA lesional hair follicles (HFs) overexpress NKG2D and γδTCR activating ligands, e.g. MICA and CD1d, and chemoattractants for γδT-cells, such as CXCL10. OBJECTIVE: To investigate whether abnormal activities of γδT-cells may be involved in AA pathogenesis. METHODS: We analyzed the number and activation status of γδT-cells in human healthy, lesional and non-lesional AA scalp biopsies by FACS and/or quantitative (immuno-)histomorphometry. RESULTS: In healthy human scalp skin, the few skin-resident γδT-cells were found to be mostly Vδ1+, non-activated (CD69-NKG2Ddim) and positive for CXCL10, and CXCL12 receptors. These Vδ1+T-cells predominantly localized in/around the HF infundibulum. In striking contrast, the number of Vδ1+T-cells was significantly higher around and even inside the proximal (suprabulbar and bulbar) epithelium of lesional AA HFs. These cells also showed a pro-inflammatory phenotype, i.e. higher NKG2D, and IFN-γ and lower CD200R expression. Importantly, more pro-inflammatory Vδ1+T-cells were seen also around non-lesional AA HFs. Lesional AA HFs also showed significantly higher expression of CXCL12. CONCLUSION: Our pilot study introduces skin-resident γδT-cells as a previously overlooked, but potentially important, mostly (auto-)antigen-independent, new innate immunity protagonist in AA pathobiology. The HF infiltration of these activated, IFN-γ-releasing cells already around non-lesional AA HFs suggest that Vδ1+T-cells are involved in the early stages of human AA pathobiology, and may thus deserve therapeutic targeting for optimal AA management.