Predicting posttransplantation diabetes mellitus by regulatory T-cell phenotype: implications for metabolic intervention to modulate alloreactivity

Abstract

Chronic inflammation and decreased frequency of regulatory T cells (Tregs) in visceral adipose tissue contribute to the propagation of insulin resistance to diabetes mellitus. We tested the hypothesis that new-onset posttransplantation diabetes mellitus (PTDM) is associated with measurable changes in Treg subsets after allogeneic hematopoietic stem cell transplantation (HSCT). PTDM before day 100 and Treg phenotype at engraftment were determined in 36 HSCT recipients without preceding history of diabetes mellitus. Among patients with new-onset PTDM (N = 24), the frequency of circulating CLA(+) (skin-homing) Tregs was decreased (1.53% vs 3.99%; P = .002) and the percentage of α(4)β(7)(+) (gut-homing) Tregs was increased (17.9% vs 10.7%; P = .048). In multivariate analysis, patients with PTDM continued to demonstrate elevated ratios of α(4)β(7)(+) Tregs to CLA(+) Tregs (odds ratio, 18.1; P = .020). PTDM is associated with altered immune regulation after HSCT and could represent a target to modulate alloreactivity.

Figure 1

Treg tissue-homing subsets, PTDM, and transplant outcomes. (A) Multiparameter analysis of Treg tissue-homing subsets. Treg tissue-homing subset identification using 10-color multiparametric flow cytometry. Gates were initially set on CD3⁺ while excluding cells expressing CD14 or marking with the amine viability dye (data not shown). Viable CD4⁺ T cells were then selected by gating on CD4⁺CD8⁻ cells. To ensure adequate cell numbers for accurate gating, quadrants were created using 2-parameter comparisons assessing the expression of Foxp3, CD25, CD127, CD45R0, α4β7, and CLA by the total CD4⁺ cell population (data not shown). These gates were then sequentially applied to the CD4⁺ cell population to determine Treg subset frequency. (B-C) Overall survival and nonrelapse mortality of patients undergoing HSCT stratified by the presence of PTDM. (D-E) PTDM was associated with changes in Treg tissue-homing phenotype. The percentage of CLA⁺ Tregs and α₄β₇⁺ Tregs was determined by multiparametric flow cytometry at the time of neutrophil engraftment. Box plots define the values for median, range, and 25th and 75th percentiles. Two-tailed P values were calculated using the Mann-Whitney U test to assess for differences in the median percentage of CLA⁺ Tregs and α₄β₇⁺ among patients with or without PTDM.