Background: Podocyte injury plays a crucial role in the pathogenesis and progression of diabetic nephropathy (DN). We investigated whether patients with diabetes mellitus (DM) without overt DN present podocyte markers in urine suggestive of early podocyte injury. Methods: We studied 71 patients with DM type 2 and normal urine albumin excretion (UAE) and 39 non-diabetic controls. The mRNA abundance of 3 podocyte-specific markers in urinary sediment (nephrin, podocin and synaptopodin) was measured with real-time quantitative PCR. All the subjects were categorized according to their urinary podocyte marker profile into 2 groups, those with only synaptopodin mRNA presence (synaptopodin only group) and those with nephrin and/or podocin mRNA presence in addition to synaptopodin in their urine (nephrin and/or podocin group). Results: Synaptopodin mRNA was detected in the urine of all the diabetics and controls. The presence of nephrin and/or podocin mRNA in urine was more frequent among DM patients compared to controls (53.5 vs. 30.8%, respectively; p = 0.022). Binary logistic regression analysis revealed that the only significant predictor of the presence of nephrin and/or podocin mRNA in urine was the presence of DM (OR 2.59, 95% CI 1.14-5.91, p = 0.024, adjusted for all risk factors). A strong correlation between nephrin and podocin urinary mRNA levels was noted (r = +0.796, p < 0.001). Conclusion: This study demonstrated that urinary podocyte markers are more prevalent in diabetic patients with normal UAE compared to controls, and this may reflect early podocyte injury. DM is the only significant determinant of the presence of nephrin and/or podocin mRNA in urine in this population. Therefore, urinary podocyte markers may emerge as a valuable tool in the early diagnosis of DN.

Keywords:
Diabetes, Diabetic nephropathy, Podocyte
1.
Collins AJ, Foley RN, Chavers B, Gilbertson D, Herzog C, Johansen K, Kasiske B, Kutner N, Liu J, St Peter W, Guo H, Gustafson S, Heubner B, Lamb K, Li S, Li S, Peng Y, Qiu Y, Roberts T, Skeans M, Snyder J, Solid C, Thompson B, Wang C, Weinhandl E, Zaun D, Arko C, Chen SC, Daniels F, Ebben J, Frazier E, Hanzlik C, Johnson R, Sheets D, Wang X, Forrest B, Constantini E, Everson S, Eggers P, Agodoa L: United States Renal Data System 2011 Annual Data Report: Atlas of chronic kidney disease & end-stage renal disease in the United States. Am J Kidney Dis 2012;59(1 suppl 1):A7. e1-e420.
2.
Zelmanovitz T, Gerchman F, Balthazar AP, Thomazelli FC, Matos JD, Canani LH: Diabetic nephropathy. Diabetol Metab Syndr 2009;1:10.
3.
KDOQI: KDOQI clinical practice guidelines and clinical practice recommendations for diabetes and chronic kidney disease. Am J Kidney Dis 2007;49(2 suppl 2):S12-S154.
4.
Standards of medical care in diabetes - 2015. Diabetes Care 2015;38(suppl):S1-S2.
5.
de Boer IH, Rue TC, Hall YN, Heagerty PJ, Weiss NS, Himmelfarb J: Temporal trends in the prevalence of diabetic kidney disease in the United States. JAMA 2011;305:2532-2539.
6.
Shankland SJ: The podocyte's response to injury: role in proteinuria and glomerulosclerosis. Kidney Int 2006;69:2131-2147.
7.
Stitt-Cavanagh E, MacLeod L, Kennedy C: The podocyte in diabetic kidney disease. ScientificWorldJournal 2009;9:1127-1139.
8.
Ziyadeh FN, Wolf G: Pathogenesis of the podocytopathy and proteinuria in diabetic glomerulopathy. Curr Diabetes Rev 2008;4:39-45.
9.
Chen HC, Chen CA, Guh JY, Chang JM, Shin SJ, Lai YH: Altering expression of alpha3beta1 integrin on podocytes of human and rats with diabetes. Life Sci 2000;67:2345-2353.
10.
Jefferson JA, Shankland SJ, Pichler RH: Proteinuria in diabetic kidney disease: a mechanistic viewpoint. Kidney Int 2008;74:22-36.
11.
Jim B, Ghanta M, Qipo A, Fan Y, Chuang PY, Cohen HW, Abadi M, Thomas DB, He JC: Dysregulated nephrin in diabetic nephropathy of type 2 diabetes: a cross sectional study. PLoS One 2012;7:e36041.
12.
Susztak K, Raff AC, Schiffer M, Böttinger EP: Glucose-induced reactive oxygen species cause apoptosis of podocytes and podocyte depletion at the onset of diabetic nephropathy. Diabetes 2006;55:225-233.
13.
Pagtalunan ME, Miller PL, Jumping-Eagle S, Nelson RG, Myers BD, Rennke HG, Coplon NS, Sun L, Meyer TW: Podocyte loss and progressive glomerular injury in type II diabetes. J Clin Invest 1997;99:342-348.
14.
Toyoda M, Najafian B, Kim Y, Caramori ML, Mauer M: Podocyte detachment and reduced glomerular capillary endothelial fenestration in human type 1 diabetic nephropathy. Diabetes 2007;56:2155-2160.
15.
Nakamura T, Kawagoe Y, Koide H: Effect of cigarette smoking on urinary podocyte excretion in early diabetic nephropathy. Diabetes Care 2003;26:1324-1325.
16.
Nakamura T, Ushiyama C, Osada S, Hara M, Shimada N, Koide H: Pioglitazone reduces urinary podocyte excretion in type 2 diabetes patients with microalbuminuria. Metabolism 2001;50:1193-1196.
17.
Nakamura T, Ushiyama C, Shimada N, Sekizuka K, Ebihara I, Hara M, Koide H: Effect of the antiplatelet drug dilazep dihydrochloride on urinary podocytes in patients in the early stage of diabetic nephropathy. Diabetes Care 2000;23:1168-1171.
18.
Nakamura T, Ushiyama C, Suzuki S, Hara M, Shimada N, Ebihara I, Koide H: Urinary excretion of podocytes in patients with diabetic nephropathy. Nephrol Dial Transplant 2000;15:1379-1383.
19.
Wang G, Lai FM, Lai KB, Chow KM, Kwan BC, Li PK, Szeto CC: Urinary messenger RNA expression of podocyte-associated molecules in patients with diabetic nephropathy treated by angiotensin-converting enzyme inhibitor and angiotensin receptor blocker. Eur J Endocrinol 2008;158:317-322.
20.
Wang G, Lai FM, Lai KB, Chow KM, Li KT, Szeto CC: Messenger RNA expression of podocyte-associated molecules in the urinary sediment of patients with diabetic nephropathy. Nephron Clin Pract 2007;106:c169-c179.
21.
Zheng M, Lv LL, Ni J, Ni HF, Li Q, Ma KL, Liu BC: Urinary podocyte-associated mRNA profile in various stages of diabetic nephropathy. PLoS One 2011;6:e20431.
22.
Levey AS, Stevens LA, Schmid CH, Zhang YL, Castro AF 3rd, Feldman HI, Kusek JW, Eggers P, Van Lente F, Greene T, Coresh J; CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration): A new equation to estimate glomerular filtration rate. Ann Intern Med 2009;150:604-612.
23.
Griffin SV, Petermann AT, Durvasula RV, Shankland SJ: Podocyte proliferation and differentiation in glomerular disease: role of cell-cycle regulatory proteins. Nephrol Dial Transplant 2003;18(suppl 6):vi8-vi13.
24.
Kriz W, Lemley KV: The role of the podocyte in glomerulosclerosis. Curr Opin Nephrol Hypertens 1999;8:489-497.
25.
Phillips A, Janssen U, Floege J: Progression of diabetic nephropathy. Insights from cell culture studies and animal models. Kidney Blood Press Res 1999;22:81-97.
26.
Baelde HJ, Eikmans M, Lappin DW, Doran PP, Hohenadel D, Brinkkoetter PT, van der Woude FJ, Waldherr R, Rabelink TJ, de Heer E, Bruijn JA: Reduction of VEGF-A and CTGF expression in diabetic nephropathy is associated with podocyte loss. Kidney Int 2007;71:637-645.
27.
Bonnet F, Cooper ME, Kawachi H, Allen TJ, Boner G, Cao Z: Irbesartan normalises the deficiency in glomerular nephrin expression in a model of diabetes and hypertension. Diabetologia 2001;44:874-877.
28.
Doublier S, Salvidio G, Lupia E, Ruotsalainen V, Verzola D, Deferrari G, Camussi G: Nephrin expression is reduced in human diabetic nephropathy: evidence for a distinct role for glycated albumin and angiotensin II. Diabetes 2003;52:1023-1030.
29.
Langham RG, Kelly DJ, Cox AJ, Thomson NM, Holthöfer H, Zaoui P, Pinel N, Cordonnier DJ, Gilbert RE: Proteinuria and the expression of the podocyte slit diaphragm protein, nephrin, in diabetic nephropathy: effects of angiotensin converting enzyme inhibition. Diabetologia 2002;45:1572-1576.
30.
Meyer TW, Bennett PH, Nelson RG: Podocyte number predicts long-term urinary albumin excretion in Pima Indians with type II diabetes and microalbuminuria. Diabetologia 1999;42:1341-1344.
31.
Turk T, Leeuwis JW, Gray J, Torti SV, Lyons KM, Nguyen TQ, Goldschmeding R: BMP signaling and podocyte markers are decreased in human diabetic nephropathy in association with CTGF overexpression. J Histochem Cytochem 2009;57:623-631.
32.
Craici IM, Wagner SJ, Bailey KR, Fitz-Gibbon PD, Wood-Wentz CM, Turner ST, Hayman SR, White WM, Brost BC, Rose CH, Grande JP, Garovic VD: Podocyturia predates proteinuria and clinical features of preeclampsia: longitudinal prospective study. Hypertension 2013;61:1289-1296.
33.
Kelder TP, Penning ME, Uh HW, Cohen D, Bloemenkamp KW, Bruijn JA, Scherjon SA, Baelde HJ: Quantitative polymerase chain reaction-based analysis of podocyturia is a feasible diagnostic tool in preeclampsia. Hypertension 2012;60:1538-1544.
34.
Sabino AR, Teixeira Vde P, Nishida SK, Sass N, Mansur JB, Kirsztajn GM: Detection of podocyturia in patients with lupus nephritis. J Bras Nefrol 2013;35:252-258.
35.
Wickman L, Afshinnia F, Wang SQ, Yang Y, Wang F, Chowdhury M, Graham D, Hawkins J, Nishizono R, Tanzer M, Wiggins J, Escobar GA, Rovin B, Song P, Gipson D, Kershaw D, Wiggins RC: Urine podocyte mRNAs, proteinuria, and progression in human glomerular diseases. J Am Soc Nephrol 2013;24:2081-2095.
36.
Yu D, Petermann A, Kunter U, Rong S, Shankland SJ, Floege J: Urinary podocyte loss is a more specific marker of ongoing glomerular damage than proteinuria. J Am Soc Nephrol 2005;16:1733-1741.
37.
Wang G, Lai FM, Lai KB, Chow KM, Kwan BC, Li KT, Szeto CC: Intra-renal and urinary mRNA expression of podocyte-associated molecules for the estimation of glomerular podocyte loss. Ren Fail 2010;32:372-379.
38.
Mundel P, Schwarz K, Reiser J: Podocyte biology: a footstep further. Adv Nephrol Necker Hosp 2001;31:235-241.
39.
Hara M, Yanagihara T, Hirayama Y, Ogasawara S, Kurosawa H, Sekine S, Kihara I: Podocyte membrane vesicles in urine originate from tip vesiculation of podocyte microvilli. Hum Pathol 2010;41:1265-1275.
40.
Mundel P: [Synaptopodin: an actin-associated protein of telencephalic dendrites and of podocytes in the kidney glomerulus]. Ann Anat 1998;180:391-392.
41.
do Nascimento JF, Canani LH, Gerchman F, Rodrigues PG, Joelsons G, dos Santos M, Pereira S, Veronese FV: Messenger RNA levels of podocyte-associated proteins in subjects with different degrees of glucose tolerance with or without nephropathy. BMC Nephrol 2013;14:214.
42.
Hara M, Yamagata K, Tomino Y, Saito A, Hirayama Y, Ogasawara S, Kurosawa H, Sekine S, Yan K: Urinary podocalyxin is an early marker for podocyte injury in patients with diabetes: establishment of a highly sensitive ELISA to detect urinary podocalyxin. Diabetologia 2012;55:2913-2919.
43.
Burger D, Thibodeau JF, Holterman CE, Burns KD, Touyz RM, Kennedy CR: Urinary podocyte microparticles identify prealbuminuric diabetic glomerular injury. J Am Soc Nephrol 2014;25:1401-1407.
44.
Ng DP, Tai BC, Tan E, Leong H, Nurbaya S, Lim XL, Chia KS, Wong CS, Lim WY, Holthöfer H: Nephrinuria associates with multiple renal traits in type 2 diabetes. Nephrol Dial Transplant 2010;26:2508-2514.
45.
Szeto CC, Lai KB, Chow KM, Szeto CY, Yip TW, Woo KS, Li PK, Lai FM: Messenger RNA expression of glomerular podocyte markers in the urinary sediment of acquired proteinuric diseases. Clin Chim Acta 2005;361:182-190.
46.
Glassock RJ: Con: Kidney biopsy: an irreplaceable tool for patient management in nephrology. Nephrol Dial Transplant 2015;30:528-531.
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2015
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