title: Urinary podocalyxin, the novel biomarker for detecting early renal change in obesity.
abstract: BACKGROUND
  The prevalence of obesity is increasing during the past decade along with obesity-related glomerulopathy (ORG), glomeruli injury due to the obesity. The major pathogenesis of ORG is the shedding of podocytes from the glomerular cell barrier into urine. Podocalyxin (PCX), a main surface antigen of podocyte, correlates well with glomerulosclerosis progression and glomerular injury severity, and might be a potential biomarker for early renal alteration in obesity. In addition, vascular endothelial growth factor (VEGF) and alpha-smooth muscle actin (α-SMA) also play a role in promoting glomerulosclerosis. The aim of this study was to explore whether obese subjects without other diseases excrete more PCX-positive (PCX+) cells than non-obese individuals, in comparison with urine protein-creatinine ratio (UPCR) and glomerular filtration rate (GFR) as traditional renal markers. Moreover, the effect of body mass index (BMI) on urinary VEGF, PCX or α-SMA positive cells was also investigated.
  
  
  METHODS
  Forty-eight obese and 13 non-obese adults were included. Exfoliated cells from fresh first void morning urine were harvested, stained with PCX, VEGF, and α-SMA antibody, and quantified by flow cytometry. Correlation between interested urinary biomarkers (cells positive for PCX, VEGF plus PCX and α-SMA), UPCR and GFR with BMI and metabolic risk factors were analyzed.
  
  
  RESULTS
  Obese patients had significantly higher PCX+ cells than non-obese [0.62 (0.00-13.13) vs. 0.15 (0.00-0.72) cells/ml × mg cr, p < 0.05]. There was no significant difference in GFR and UPCR between the groups. Of interest, BMI demonstrated a correlation with PCX+ cells (r = 0.343, p = 0.008) and cells positive for PCX plus VEGF (r = 0.374, p = 0.004).
  
  
  CONCLUSIONS
  Obese subjects without other diseases and with normal UPCR and GFR showed evidence of renal alteration through the detection of a higher number of PCX+ cells. Increasing BMI also resulted in higher number of PCX+ cells.
authors.affiliation: Department of Internal Medicine, Faculty of Medicine, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok, 10330, Thailand. jjiabjiab@hotmail.com.
authors.forename: Chayanut
authors.initials: C
authors.lastname: Suwanpen
authors.affiliation: Pasteur Institute du Laos, Samsenthai Road, Ban Kao-Gnot, Sisattanak district, P.O Box 3560, Vientiane, Lao PDR. thip_mt@hotmail.com.
authors.forename: Phonethipsavanh
authors.initials: P
authors.lastname: Nouanthong
authors.affiliation: Department of Internal Medicine, University of Hawaii, 1356 Lusitana Street, Honolulu, HI, 96813, USA. veeravich_j@hotmail.com.
authors.forename: Veeravich
authors.identifier: http://orcid.org/0000-0002-3419-2296
authors.initials: V
authors.lastname: Jaruvongvanich
authors.affiliation: Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. doctorkrit@gmail.com.|Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. doctorkrit@gmail.com.
authors.forename: Krit
authors.initials: K
authors.lastname: Pongpirul
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. awannarat@yahoo.com.
authors.forename: Wannarat Amornnimit
authors.initials: WA
authors.lastname: Pongpirul
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. a_leelahavanit@yahoo.com.|Immunology Unit, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. a_leelahavanit@yahoo.com.
authors.forename: Asada
authors.initials: A
authors.lastname: Leelahavanichkul
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. golfnephro@hotmail.com.|Kidney and Metabolic Research Unit, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. golfnephro@hotmail.com.
authors.forename: Talerngsak
authors.initials: T
authors.lastname: Kanjanabuch
mesh_terms: D015415:Biomarkers / Q000652:urine; D015992:Body Mass Index; D016022:Case-Control Studies; D003404:Creatinine / Q000652:urine; D042241:Early Diagnosis; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000652:urine*; D009765:Obesity / Q000150:complications* / Q000175:diagnosis; D050199:Podocytes / Q000378:metabolism*; D011237:Predictive Value of Tests; D011507:Proteinuria / Q000175:diagnosis / Q000209:etiology / Q000652:urine; D012795:Sialoglycoproteins / Q000652:urine*; D016482:Urinalysis; D014556:Urine / Q000166:cytology
chemical_list: D015415:Biomarkers; D012795:Sialoglycoproteins; C001643:podocalyxin; D003404:Creatinine
keywords: Metabolic syndrome; Obesity; Podocalyxin; Podocyte; Proteinuria