Fig. 4

EP4 expression in Th17 cells is associated with high disease activity in AS. a EP4 expression levels in AS patients with low or high BASDAI values. EP4 expression was analyzed by flow cytometry in IL-17⁺ purified CD4⁺ T cells after 4 days of in vitro cell culture and is presented as MFI. b PTGER4 expression in patients with low or high BASDAI values. PTGER4 expression was assessed by RT-PCR. Th17 cells were induced in vitro for 4 days from naïve CD4⁺CD45RA⁺ T cells under Th17-skewing conditions. c IL-17 expression in AS patients with low or high BASDAI values. Cells were analyzed by flow cytometry. The percentage of positive cells is shown. d Correlation between BASDAI and EP4 expression in Th17 cells, e between EP4 and IL-17 expression, f between BASDAI and IL-17 expression as well as correlation of EP4 with g disease duration, h age of patients and i sex (same cells as in Fig. 1f were used). Spearman r correlation and Mann-Whitney test were used to determine the significance