Fig. 2

The number of CD8 + senescent T cells in middle-age group decreased significantly after metformin treatment. (a) Frequency of CD3 + CD8 + CD45RA + /CD45RO + CCR7-CD27-CD28- cells which gated on CD3 + CD8 + T cells treated with the different concentrations of metformin (0 mM, 5 mM, 10 mM or 20 mM). Quantification of the percentage of CD8 + senescent T cells derived from Teff cells (CD3 + CD8 + CD45RA + CCR7-CD27-CD28-CD57 + KLRG1 +) (b) and Tem cells (CD8 + CDR45RO + CCR7-CD27-CD28-CD57 + KLRG1 +) (c) at middle-age group with 20 mM metformin treatment. Expressed as the mean ± SEM. ***P < 0.001; Mann–Whitney test (two-tailed) and paired Student’s t-test. Teff, effector T cells; Tem, effector memory T cells; Met(-), control; Met( +), 20 mM metformin treatment