AUTHOR=Sefik Esen , Hori Shohei , Vasanthakumar Ajithkumar TITLE=Editorial: Regulatory T Cell Heterogeneity: Canonical and Non-Canonical Functions JOURNAL=Frontiers in Immunology VOLUME=12 YEAR=2021 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.722563 DOI=10.3389/fimmu.2021.722563 ISSN=1664-3224