CCL2 and Bloom syndrome: Compared with the control group, Col1a1, Timp1, Ccl2, and Serpinb2 expression levels were increased to 5.5-fold, 4.2-fold, 3.9-fold, and 3.1-fold, respectively, while that of Tbx21 decreased to 2.5-fold in the BLM group (all P < 0.05, Figure 2E-I).