Variable frequencies of peripheral T-lymphocyte subsets in the diabetes spectrum from type 1 diabetes through latent autoimmune diabetes in adults (LADA) to type 2 diabetes

Abstract

T lymphocytes are key players in the pathogenesis of autoimmune diabetes. We recruited subjects with T1D (n=81), LADA (n=82), T2D (n=95) and NGT (n=218) and analyzed the percentages of T-lymphocyte subsets, including T helper 1 (Th1), T helper 2 (Th2), T helper 17 (Th17), T cytotoxic 1 (Tc1), regulatory T cells (Tregs), effector T (Teff), naïve T, central memory T (Tcm), and effector memory T (Tem) cells by flow cytometry. LADA patients possessed similar frequencies of IFN-γ⁺CD4⁺ T (Th1), IFN-γ⁺CD8⁺ T and CD4⁺ Teff cells compared with T1D patients, but much lower than those of NGT subjects. Like T2D patients, LADA patients had increased frequencies of CD4⁺ Tem and CD8⁺ Tem cells with respect to T1D and NGT subjects. In LADA patients, Th2 cells were decreased while CD4⁺ Tcm cells were increased compared with NGT subjects. Notably, we observed significant negative correlations between the CD4⁺ Tcm cell frequency and C-peptide in LADA subjects. These data demonstrates that LADA patients possess T-cell subset changes resembling both T1D and T2D and represent the middle of the diabetes spectrum between T1D and T2D. Based on these T-cell subset alterations, we speculate that autoimmunity-induced β-cell destruction and inflammation-induced insulin resistance might both be involved in the pathogenesis of LADA.

Keywords: CD4+ Tcm cells; LADA; T-lymphocytes; T1D; T2D; Th1 cells.

Figure 1

Flow cytometry of peripheral T-cell subsets. (A) Representative dot plot showing the gating strategy for IFN-γ⁺CD4⁺ T, Th2 and Th17 cells. (B) Representative dot plot showing the gating strategy for Tregs. (C, D) Representative dot plot showing the gating strategy for naïve and memory T cells gated on CD4⁺ T/CD8⁺ T cells.

Figure 2

The frequency of peripheral T-cell subsets in diabetic patients and control subjects. The frequency of IFN-γ⁺CD4⁺ T (A) and IFN-γ⁺CD8⁺ T (B) cells gated on CD4⁺ T or CD8⁺ T cells, CD4⁺ Teff (C) and CD4⁺ Tem(D) gated on CD4⁺ T cells, CD8⁺ Tem (E) gated on CD8⁺ T cells, CD4⁺ Tcm (F) and Th2 cells (G) gated on CD4⁺ T cells, CD4⁺ T cells(H) gated on lymphocytes, Th17 cells (I)gated on CD4⁺ T cells, and CD8⁺ Tcm cells (J) gated on CD8⁺ T cells in NGT subjects and T2D, LADA and T1D patients as determined by flow cytometry. P values refer to comparisons of data after adjustment for age and sex. Each point represents the percentage of T-cell subsets of an individual. Graphs show the median and interquartile range. *p<0.05, **p<0.01, ***p<0.001.

Figure 3

The frequency of peripheral T-cell subsets in new-onset diabetic patients and control subjects. The frequency of IFN-γ⁺CD8⁺ T (A) cells gated on CD8⁺ T cells, CD4⁺ Tem cells(B) gated on CD4⁺ T cells, CD8⁺ Tem cells(C) gated on CD8⁺ T cells, and CD8⁺ naïve T cells (D) gated on CD8⁺ T cells in NGT subjects and new-onset T2DM, LADA and T1DM patients as determined by flow cytometry. P values refer to comparisons of data after adjustment for age and sex. Each point represents the percentage of T-cell subsets of an individual. Graphs show the median and interquartile range. *p<0.05, **p<0.01, ***p<0.001.