These results were confirmed by the validation cohort, in which serum PTX3 levels were also significantly higher than that in SLE without renal involvement group (3.589 (0.007–45.364) vs. 1.065 (0.040–9.098) ng/ml, P < 0.001), minimal change disease group (3.589 (0.007–45.364) vs. 1.021 (0.105–2.940) ng/ml, P < 0.001) and normal controls (3.589 (0.007–45.364) vs. 0.993 (0.007–2.655) ng/ml, P < 0.001) (Figure 1A). Here, PTX3 is linked to systemic lupus erythematosus.