Abstract: FR-PO365
Comparative Analysis of Regulatory T Cell Subpopulations in CKD Outpatients and Healthy Controls
Session Information
- CKD: Mechanisms - II
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 2103 CKD (Non-Dialysis): Mechanisms
Authors
- Negi, Neema, National University of Ireland Galway, Galway, Ireland
- Cormican, Sarah, National University of Ireland Galway, Galway, Ireland
- O Coileain, Eanna, National University of Ireland Galway, Galway, Ireland
- Griffin, Matthew D., National University of Ireland Galway, Galway, Ireland
Background
Regulatory T cells (T-reg) suppress autoimmunity/inflammation and allo-antigen-specific immune response in transplantation. Consequently, ex vivo-expanded T-reg are a promising immunomodulatroy therapy. In CKD/ESRD, circulating T-reg numbers are peserved and can be culture-expanded. Nonetheless, T-reg sub-phenotypes and their relevance to CKD pathophsiology are not fully characterised. We aimed to compare relative proportions and surface phenotype characteristics of circulating T-reg subpopulations in adult CKD outpatients and healthy adults.
Methods
Blood samples and clinical information were provided by CKD outpatients without immune-mediated disease (n=35, eGFR:11-64) and by healthy volunteers (HV, n=20). Multi-color flow cytometry was performed on fresh PBMC for CD4, CD25, CD127 and FoxP3 (to identify T-reg) and for CD45RA, HLA-DR, TNFR2, CCR7, CD62L and CD39 (to define subpoulations and their functional markers).
Results
Peripheral blood CD4+CD25+CD127lo T-reg (confirmed to be FoxP3+) were identified and subdivided into 3 subpopulations based on expression of CD45RA and HLA-DR [RA+DR-, RA-DR+, RA-DR-]. No difference in T-reg frequency (expressed as % of total CD4+ T-cells) was seen between CKD and HV. However, RA-DR- T-reg were proportionately increased and RA+DR- T-reg were proportionately decreased in CKD (p<0.0001), consistent with a relative expantion of "antigen experienced" T-reg. In regard to surface proteins of potential functional importance, the selectin CD62L was expressed at higher level on total T-reg of CKD vs. HC (average MFI 3810 vs 1299, p=0.0002) as well on each of the 3 T-reg subpopulations. In contrast, surface expression of the ectonuclease CD39 (which dephosphorylates ATP and ADP) was lower on total T-reg (average MFI 665 vs 6936, p<0.0001) and was present on lower proportions of RA-DR+ T-reg (average 53.0% vs 87.1%, p=0.001) and RA-DR- T-reg (average 36.6% vs 73.8%, p<0.0001) in CKD vs. HV. Expression of CCR7 and TNF receptor 2 (TNFR2) did not differ for T-reg and T-reg subpopulations of CKD and HV.
Conclusion
Although adults with CKD had comparable blood T-reg numbers compared to HV, they differed in the relative frequencies of CD45RA/HLA-DR-defined T-reg subpopulations and in expression of proteins that could reflect alterations in migration patterns (CD62L) and specific regulatory functions (CD39).
Funding
- Private Foundation Support