Urine Polypeptide Study Of Chronic Kidney Disease Based On Mass Spectrometry

Background:Chronic kidney disease(CKD)is a public health problem worldwide.Early diagnosis and early treatment are needed to monitor the response to treatment and prevent disease progression.Percutaneous renal biopsy is currently the "gold standard" for diagnosis,but this invasive technique can cause complications,is contraindicated in some cases,and patients cannot easily repeat biopsies during follow-up.Therefore,non-invasive diagnostic methods must be found.Urine peptides can reflect the pathophysiology of the kidney and can be used as potential diagnostic biomarkers.Objective:1.To construct a diagnostic model of urine peptide spectrum of CKD patients with the new generation of MALDI-TOF MS,to establish a differential diagnosis model that distinguishes IgA nephropathy from other chronic kidney disease(otherCKD),to establish a classification model to distinguish the pathological grade of IgA nephropathy.2.To explore urinary polypeptide markers that can be used to monitor the efficacy of IgA nephropathy and membranous nephropathy.Methods:Part 1 New CKD patients admitted to Nanfang Hospital of Southern Medical University,Zhujiang Hospital of Southern Medical University,and Guangdong Provincial Hospital of Traditional Chinese Medicine were taken as the research objects.CKD patients diagnosed by percutaneous renal biopsy after admission were the case group,and healthy volunteers of the same age group were the control group.Fresh,first-morning urine samples were collected from the participants on the same day that the renal biopsy was performed,and the urine was analyzed by mass spectrometry using QuanTOF MS.The bioinformatics analysis was performed on the mass spectrometry data of each group:CKD group and healthy control group;IgA nephropathy group and healthy control group;IgA nephropathy group and other chronic kidney disease(otherCKD)group,the otherCKD group included membranous nephropathy,minimal change disease,focal segmental glomerulosclerosis,membranoproliferative glomerulonephritis,diabetic nephropathy and lupus nephritis;IgA nephropathy group and membranous nephropathy group.Modeled by random forest algorithm using differential urine peptide profile data.Based on Lee’s pathological classification of IgA nephropathy,the urine peptide profiles of different grades were analyzed and modeled by random forest algorithm.Quantof MS and LC-MSMS mass spectrometry were used to identify the peptides.Part 2 Patients with IgA nephropathy and patients with membranous nephropathy who regularly consultde in Zhujiang Hospital of Southern Medical University and Guangdong Provincial Hospital of Traditional Chinese Medicine were included in the study.Patients with IgA nephropathy and membranous nephropathy who have been treated for more than one year are included.According to the quantitative results of urine protein,each disease is divided into two groups:good efficacy group(urine microalbumin<0.2g/L),poor efficacy group(urine microalbumin>lg/L).Healthy volunteers of the same age group were used as the control group.A classification model is established by a random forest algorithm.Compare the peak intensities of key peptides between groups.Quantof MS and LC-MSMS mass spectrometry were used to identify the peptides.Results:1.A classification model was established to distinguish CKD from healthy controls,with an AUC of 97.54%.A classification model was established to distinguish IgA nephropathy from other chronic kidney disease(otherCKD),The AUC was 83.97%.Alpha-l-antitrypsin、Fibrinogen alpha chain、IGKV3-20 and Collagen alpha-1 can be used as biomarkers to identify IgA nephropathy and otherCKD.A classification model of IgA nephropathy and membranous nephropathy was established,clinical indicators and urine peptide profiles were combined for modeling,with an AUC of 98.85%.A classification model was identified that distinguished IgA nephropathy LeeⅡ-Ⅲ and IgA nephropathy LeeⅣ-Ⅴ pathological grade,AUC 83.22%.2.Urine peptide profiles of the IgA nephropathy and membranous nephropathy groups were significantly different from those of the poorly effective group,and the urine peptide profiles of the effective group were close to healthy control.al-antitrypsin,Period circadian protein homolog 1,methyltransferase-like protein 5,Putative inactive cytochrome P450 2G1 and Tripartite motif-containing protein 45 can be used to monitor the efficacy of IgA nephropathy and membranous nephropathy.Conclussion:1.A diagnostic model of urine peptide spectrum of chronic kidney disease was constructed;a differential diagnosis model of urine peptide spectrum of IgA nephropathy and other chronic kidney diseases was established;A classification model was established to distinguish between IgA nephropathy and membranous nephropathy;it was found that a urine peptide profile that can distinguish the pathological grade of IgA nephropathy.2.There were significant differences in urine polypeptide spectrum between IgA nephropathy with different therapeutic effects and between membranous nephropathy with different therapeutic effects.Urine peptide markers that can be used for efficacy monitoring were identified.