Fig 2: Cartilage oligosaccharide matrix protein (COMP) messenger RNA (mRNA) and protein relative expression ratio under different concentrations of T-2 toxin intervention. a) COMP mRNA relative expression ratio under different concentrations of T-2 toxin intervention. Note: Compared with the control group, *p < 0.05. Using Dunnett-t test, 2 ng/ml and 5 ng/ml T-2 toxin concentration intervention group were statistically significant compared to 0 ng/ml toxin intervention group. b) COMP protein relative expression of integrated optical density (IOD) values under different T-2 toxin concentrations. Note: Using Dunnett-t test, the values in 1 ng/ml, 2 ng/ml, and 5 ng/ml T-2 toxin concentration intervention groups were found to be statistically significant compared with the 0 ng/ml toxin intervention group, respectively, **p < 0.01. c) The western blot band of COMP and reference protein in four groups with different T-2 toxin treatment concentrations. GADPH, glyceraldehyde-3-phosphate dehydrogenase.

Fig 3: Effects of cartilage oligosaccharide matrix protein (COMP) overexpression on downstream genes in Kashin-Beck disease (KBD) chondrocyte model (the COMP overexpression was only performed for the KBD cells) among the blank control, negative control, and COMP overexpression groups. a) Compared with the COMP overexpression group, the Survivin mean messenger RNA (mRNA) relative expression ratios in the blank control group and negative control group were reduced (8.51, SD 2.88 and 6.77, SD 3.60, respectively; all **p < 0.001, Dunnett-t test). b) Compared with the COMP overexpression group, the sex-determining region Y-box 9 (SOX9) mean mRNA relative expression ratios in the blank control group and negative control group were reduced (5.61, SD 0.87 and 7.71, SD 2.17, respectively; **p < 0.001 , Dunnett-t test). c) Compared with the COMP overexpression group, the Caspase 3 mean mRNA relative expression ratios in the blank control group and negative control group were increased (0.38, SD 0.05 and 0.38, SD 0.04, respectively; all **p < 0.001, Dunnett-t test). d) Compared with the COMP overexpression group, the type II collagen mean mRNA relative expression ratios in the blank control group and negative control group were reduced (4.72, SD 2.17 and 5.66, SD 1.72, respectively; all *p < 0.050, Dunnett-t test). e) Effect on x-linked inhibitor of apoptosis protein (XIAP) (p = 0.948, one-way analysis of variance (ANOVA)). f) Effect on Fas (p = 0.095, ANOVA). g) Effect on Bcl-2-associated x protein (BAX) (p = 0.347, ANOVA). h) Effect on MMP13 (p = 0.263, ANOVA).

Fig 4: a) Relative expression ratio of cartilage oligosaccharide matrix protein (COMP) overexpressing lentivirus in articular chondrocytes among the blank control, negative control, and COMP overexpression groups. Compared with the COMP overexpression group, the mean COMP expression levels in the blank control group and negative control group were reduced significantly (7.25, SD 4.69 and 10.12, SD 2.86, respectively; all **p < 0.001, Dunnett-t test). b) Effect of COMP overexpression of lentivirus on the activity of articular chondrocytes in Kashin-Beck disease (KBD) among the blank control, negative control, and COMP overexpression groups. Compared with the COMP overexpression group, the mean survival rate of KBD chondrocytes in the blank control group was reduced (1.31, SD 0.22; *p < 0.05, Dunnett-t test).