MicroRNA-31 (miR-31) is down-regulated in T cells of patients with sepsis. (A) Total RNA was extracted from purified CD3⁺ T cells of sepsis patients (n = 23, sepsis) within 48 h after clinical diagnosis as well as from CD3⁺ T cells of healthy donors (n = 16, control). Relative expression of endogenous miR-31-5p was quantified by quantitative polymerase chain reaction (qPCR) using U47 RNA as normalizing control. Left panel shows scatter dot plot with each symbol representing data from one subject. Horizontal lines delineate means ± SD. Right panel indicates fold reduction of miR-31 in T cells of the same sepsis patients versus healthy controls. Data are given as means ± SD. **P = 0.0001 in unpaired Student’s t test. (B) Blood withdrawal was repeated after a time span of 24 h in case of seven patients who were diagnosed with early-stage sepsis (symptom onset less than 4 h) and miR-31 expression was reanalyzed in CD3⁺ T cells of these individuals by qPCR. Zero and 24 h indicate blood collection and T cell separation at the time of diagnosis as well as 24 h later. Symbols with connecting lines represent data of individual subjects at the time of diagnosis (0 h) as well as 24 h later. *P = 0.0051 in paired Student’s t test. (C) Relative mRNA levels of polycomb group proteins SUZ12 (left panel) and EZH2 (right panel) were quantified in the same samples by qPCR. SUZ12: *P = 0.022 in paired Student’s t test and EZH2: *P = 0.0469 in Wilcoxon signed-rank test. SDHA = succinate dehydrogenase subunit A; TBP = TATA Box Binding Protein.