Supplementary Material for: Differences in urine protein profiles between preterm and full-term infants based on urine proteomic analysis

Background Urine samples could partially reflect the renal condition and could provide possible mechanism of high-risk factor for the long-term development of chronic kidney disease caused by prematurity. Methods Urine samples were collected from preterm infants (gestational age <28 weeks) when their corrected gestational weeks reached ≥37 weeks. In addition, urine samples were collected from full term infants beyond three days after birth as the control group. The urine proteome was investigated by using LC‒MS/MS analysis, and subsequent bioinformatics analysis was performed. Differentially expressed proteins were validated using ELISA. Results A total of 2634 proteins were identified, 366 proteins were highly expressed in the preterm group, while 102 proteins were enriched in the full-term group. Based on functional analysis, proteins enriched in preterm group were implicated in structure organization, cell adhesion, and extracellular part, while proteins enriched in urine of the full-term group were implicated in the immune response. Kidney inherent cells accelerated into urine have been examined in preterm infants group. Each of the top 20 differentially expressed proteins enriched in the urine of preterm infants was used as a keyword for literature retrieval, ultimately leading to the selection and validation of CDH6 and CDH11 through ELISA. Both proteins were found to be more abundant in the urine of preterm infants than in that of full-term infants. Conclusions The present study provides differences in urine protein profiles between preterm and full-term infants and a new potential explanation for the high risk of CKD development caused by preterm birth.