Abstract: Objective To investigate the relationship of the serum chitinase-3-like protein 1 (CHI3L1) and soluble fms-like tyrosine kinase-1(sFlt-1) with the severity and prognosis of IgA nephropathy patients. Methods One hundred and twenty-four patients with IgA nephropathy in Third Hospital of Peking University from September 2022 to August 2024.The cases were divided into mild, moderate and severe groups according to the severity of the disease.The prognosis was classified as good and poor prognosis groups; Serum CHI3L1 and sFlt-1 were measured by ELISA. The influencing factors of poor prognosis in IgA nephropathy patients were analyzed using logistic regression. ROC curve was plotted to analyze the diagnostic value of serum CHI3L1 and sFlt-1 in patients with severe IgA nephropathy and their predictive value for poor prognosis in IgA nephropathy patients. Results The level of serum CHI3L1,sFlt-1,Scr,BUN,24-hour urinary protein and UA in the moderate and severe groups was found to be significantly higher than that in the mild group(P＜0.05),while Hb,Alb,and eGFR were prominently lower than those in the mild group(P＜0.05).Additionally, the level of CHI3L1,sFlt-1,Scr,BUN,24-hour urinary protein and UA in the severe group were significantly higher than those in the moderate group(P＜0.05),Hb,Alb,and eGFR were obviously lower than those in the moderate group(P＜0.05). According to the ROC curve, the AUC of serum CHI3L1 and sFlt-1 in the diagnosis of severe IgA nephropathy patients was 0.833 and 0.865 respectively. The AUC of the combination of the two in the diagnosis of severe IgA nephropathy patients was 0.970,and the combination of the two was better than alone in diagnosis(Z=2.712,Z=2.725,both P＜0.05). Scr,BUN,24 h urine protein quantification and UA were significantly higher in the poor prognosis group than those in the good prognosis group(P＜0.05)and Hb,Alb and eGFR were significantly lower than in the good prognosis group(P＜0.05). Compared with the good prognosis group, the level of serum CHI3L1 and sFlt-1 were prominently higher in the poor prognosis group(P＜0.05). Multivariate logistic regression analysis revealed that CHI3L1,sFlt-1,Scr and 24-hour urinary protein quantification were risk factors predicting poor prognosis(P＜0.05) while eGFR was a protective factor(P＜0.05). According to the ROC curve, the AUC of serum CHI3L1 and sFlt-1 in predicting poor prognosis in IgA nephropathy patients was 0.820 and 0.771, respectively. The AUC of the combination of the two in predicting poor prognosis in IgA nephropathy patients was 0.879,and the combination of the two was better than single prediction(Z=2.692,Z=2.699,both P＜0.05). Conclusions The expression level of serum CHI3L1 and sFlt-1 is significantly elevated in patients with IgA nephropathy, and related to the severity and prognosis of the disease. Combined detection has certain clinical value in predicting the prognosis of patients.

Key words: IgA nephropathy, chitinase-3-like protein 1, soluble Fms-like tyrosine kinase-1, severity of disease, prognosis