(#15) Senescent phenotype of islet-infiltrating CD8+ T cells from donors with type 1 diabetes

PRESENTED BY: Sally Kent

Authors
First NameLast NameAffiliation/Institution
Jenny AurielleBabonUniversity of Massachusetts Medical School
MeganDeNicolaUniversity of Massachusetts Medical School
SambraRedickUniversity of Massachusetts Medical School
DavidHarlanUniversity of Massachusetts Medical School
AliNajiUniversity of Pennsylvania School of Medicine
ClaytonMathewsUniversity of Florida
AlvinPowersVanderbilt University School of Medicine
DirkHomannIcahn School of Medicine at Mount Sinai
Purpose
Type 1 diabetes (T1D) is thought to be caused by islet-specific T cell destruction of insulin-producing pancreatic β-cells. However, comprehensive phenotyping to better understand the composition and function(s) of islet-infiltrating T cells is needed. To this end, upon receipt of isolated islets, we have hand-picked islets from the isolates and immediately enumerated and phenotyped islet-infiltrating T cells.
 

Methods

Islets isolated from donors without diabetes were supplied by Prodo Labs and the Integrated Islet Distribution Program (IIDP) We received tissues and isolated islets from the Network of Pancreatic Organ Donors with Diabetes (nPOD), the Human Pancreas Analysis Program (HPAP, University of Pennsylvania) and from Vanderbilt University (Alvin Powers). We received freshly isolated islets with autologous pancreatic draining lymph nodes (pLN) and/or spleen from donors without a clinical diagnosis of T1D, but who were GADA+ upon demise (T1D-GADA+, HPAP) and donors with 0.42-31 years of T1D duration (nPOD and Vanderbilt University). Upon receipt, spleen and pLN were processed into single cells suspensions. Islets were hand-picked, recombinant trypsin-dispersed, stained for viability and markers for T cells subsets, memory, activation, tissue residence, and cellular senescence and analyzed by flow cytometry. Islet isolation material from one donor, nPOD 6414 (23 year old male, 0.42 years of T1D duration) was also assayed for similar markers by CyTOF.
Summary of Results
The frequency of CD4+ and CD8+ T cells derived from hand-picked islets was not statistically different among the T1D-GADA+ donors (n=4), donors with new-onset to moderate-term T1D (0.42-8 years duration, n=14), and donors with long-term T1D (10-31 years duration, n=15), but each was statistically more frequent when compared to those from control donor islets. For the donors with T1D and T1D-GADA+ donors, both CD4+ and CD8+ T cells derived from hand-picked islets demonstrated a combination of effector (TEM) and central memory (TCM) phenotypes with CD8+ cells from one T1D-GADA+ donor being 60% effector (TEFF) phenotype. From hand-picked islets of 4 donors with T1D (2, 6, 8, and 8 years duration), a subpopulation of CD8+ T cells (12-50%) were CD57hi/+PD-1+; this was also seen from 0.27% of pLN CD4+ T cells from one donor with 2 years duration of T1D. This phenotype was not seen in the islet-derived CD4+ T cells, in CD4+ and CD8+ T cells from any spleen or other pLN and not in CD4+ or CD8+ T cells from the islets/spleen/pLN from 4 donors with longer-term T1D (12, 15, 22, and 31 years duration). The phenotype of both CD8+CD103+ (tissue resident) and CD8+CD103- T cells from the islet isolation material from nPOD 6414 showed increased expression of CD57 (CyTOF).
 

Conclusions

A subpopulation of islet-infiltrating CD8+ T cells, from donors with new-onset to moderate-term T1D exhibited markers for 1) possible senescence, repeated antigen exposure, and/or cytotoxic potential (CD57) and 2) potential suppression of function by any islet cell, including β cells, expressing a ligand for PD-1, PD-1L [PMID: 29844327, 30269996] and/or PDL-2. These data have implications for the role of CD8+ T cells in progression of T1D pathogenesis, at the site of β-cell damage, and can provide targets for therapeutic interventions in T1D.