Differences in Maturation Status and Immune Phenotypes of Circulating Helios + and Helios - Treg Subpopulations and Their Disrupted Correlations With Regulatory Monocytes in Autoantibody-Positive T1D Compared to Age-Matched Healthy Individuals

CD4 Tregs are involved in the regulation of various autoimmune diseases, but believed to be highly heterogeneous. Studies have indicated that Helios controls a distinct subset of functional Tregs. However, the immunological changes in circulating Helios+ and Helios- Tregs and contributing factors for these two Treg subsets are not fully understood in type 1 diabetes (T1D). Here, we elucidated the differences in maturation status and immune regulatory phenotypes of Helios+ and Helios- Tregs and their correlations with monocyte subsets in T1D individuals. As CD25-/low Foxp3+ Tregs also represent a subset of functional Tregs, we defined Tregs as Foxp3+CD127-/low and examined circulating Helios+ and Helios- Treg subpopulations in 68 islet-specific autoantibody-positive T1D individuals and 68 age-matched autoantibody-negative healthy controls. We found that Foxp3 and CTLA4 expression diminished in Helios- Tregs, while the proportion of CD25-/low Tregs increased in Helios+ Tregs of T1D individuals. Although the frequencies of neither Helios+ nor Helios- Tregs were affected by T1D genetic risk loci, Helios+ Tregs correlated with age at T1D diagnosis negatively and disease duration positively. Moreover, for Helios+ Tregs identified by CD45RA/CCR7 expression, the negative correlation between central and effector memory proportions in healthy controls disrupted in T1D individuals. Finally, regulatory non-classical and intermediate monocytes also decreased in T1D individuals, and positive correlations between regulatory monocytes and Helios+/Helios- Treg subsets in healthy controls disappeared in T1D individuals. These findings shed new light on the immunological changes on Helios+ and Helios- Treg subsets and their correlations with other regulatory immune cells underlying T1D, which may help stratify patients for clinical trials and for monitoring immunotherapy outcomes. Funding Statement: This study was supported by grants from the National Natural Science Foundation of China (81670715), Jiangsu Province Youth Medical Talents Project (QNRC2016584), the Natural Science Foundation of Jiangsu Province (BK2012486), Jiangsu Government Scholarship for Overseas Studies (JS-2013-260), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). Declaration of Interests: The authors declare that there is no duality of interest associated with this manuscript. Ethics Approval Statement: The study was approved by the Ethics Committee from the First Affiliated Hospital of Nanjing Medical University and conducted according to the principles of the Declaration of Helsinki.