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Urinary podocyte-associated mRNA profile in various stages of diabetic nephropathy.

Zheng M, Lv LL, Ni J, Ni HF, Li Q, Ma KL, Liu BC - PLoS ONE (2011)

Bottom Line: Quantification of messenger RNA (mRNA) expression in urinary sediment by real-time PCR is emerging as a noninvasive method of screening DN-associated biomarkers.Furthermore, podocalyxin mRNA was found to negatively correlate with eGFR (r = -0.349, p = 0.01).The urinary mRNA profiles of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were found to increase with the progression of DN, which suggested that quantification of podocyte-associated molecules will be useful biomarkers of DN.

View Article: PubMed Central - PubMed

Affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, China.

ABSTRACT

Background: Podocyte injury and subsequent excretion in urine play a crucial role in the pathogenesis and progression of diabetic nephropathy (DN). Quantification of messenger RNA (mRNA) expression in urinary sediment by real-time PCR is emerging as a noninvasive method of screening DN-associated biomarkers. We hypothesized that the urinary mRNA profile of podocyte-associated molecules may provide important clinical insight into the different stages of diabetic nephropathy.

Methods: DN patients (N = 51) and healthy controls (N = 13) were enrolled in this study. DN patients were divided into a normoalbuminuria group (UAE<30 mg/g, n = 17), a microalbuminuria group (UAE 30∼300 mg/g, n = 15), and a macroalbuminuria group (UAE>300 mg/g, n = 19), according to their urinary albumin excretion (UAE). Relative mRNA abundance of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were quantified, and correlations between target mRNAs and clinical parameters were examined.

Results: The urinary mRNA levels of all genes studied were significantly higher in the DN group compared with controls (p<0.05), and mRNA levels increased with DN progression. Urinary mRNA levels of all target genes positively correlated with both UAE and BUN. The expression of podocalyxin, CD2-AP, α-actin4, and podocin mRNA correlated with serum creatinine (r = 0.457, p = 0.001; r = 0.329, p = 0.01; r = 0.286, p = 0.021; r = 0.357, p = 0.006, respectively). Furthermore, podocalyxin mRNA was found to negatively correlate with eGFR (r = -0.349, p = 0.01).

Conclusion: The urinary mRNA profiles of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were found to increase with the progression of DN, which suggested that quantification of podocyte-associated molecules will be useful biomarkers of DN.

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ROC-curve analysis of mRNA levels.Fraction of true positive results (sensitivity) and false positive results (1-specificity) for mRNA levels of synaptopodin, CD2-AP, α-actin4, podocin, and podocalyxin as predictors of DN. The calculated area under the curve was 0.726 for synaptopodin mRNA levels (95% confidence interval 0.589 to 0.864), 0.671 for CD2-AP mRNA levels (95% confidence interval 0.53 to 0.811), 0.725 for α-actin4 mRNA levels (95% confidence interval 0.582 to 0.867), 0.753 for podocalyxin mRNA levels (95% confidence interval 0.623 to 0.883), and 0.706 for podocin mRNA levels (95% confidence interval 0.559 to 0.853). A value of 0.5 is no better than that expected by chance (the  hypothesis), and a value of 1.0 reflects a perfect indicator.
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pone-0020431-g004: ROC-curve analysis of mRNA levels.Fraction of true positive results (sensitivity) and false positive results (1-specificity) for mRNA levels of synaptopodin, CD2-AP, α-actin4, podocin, and podocalyxin as predictors of DN. The calculated area under the curve was 0.726 for synaptopodin mRNA levels (95% confidence interval 0.589 to 0.864), 0.671 for CD2-AP mRNA levels (95% confidence interval 0.53 to 0.811), 0.725 for α-actin4 mRNA levels (95% confidence interval 0.582 to 0.867), 0.753 for podocalyxin mRNA levels (95% confidence interval 0.623 to 0.883), and 0.706 for podocin mRNA levels (95% confidence interval 0.559 to 0.853). A value of 0.5 is no better than that expected by chance (the hypothesis), and a value of 1.0 reflects a perfect indicator.

Mentions: ROC curves were calculated to assess the diagnostic power for each target gene in discriminating between DN patients and healthy controls. Figure 4 demonstrates the diagnostic performance of synaptopodin, podocalyxin, CD2-AP, α-actin4 and podocin in terms of AUCs when DN patients and controls were compared. As shown in Figure 4, all target genes were effectively able to discriminate between two groups, with an AUC above 0.5. The AUC was 0.753 (95% confidence interval, 0.623 to 0.883) for podocalyxin mRNA levels, which demonstrated the highest diagnostic value. The log-transformed threshold providing optimal sensitivity and specificity for podocalyxin mRNA was −3.24. Using the cutoff value of −3.24 derived from the data, podocalyxin mRNA levels predicted DN with a sensitivity of 81.4% and a specificity of 62.5% (p = 0.006).


Urinary podocyte-associated mRNA profile in various stages of diabetic nephropathy.

Zheng M, Lv LL, Ni J, Ni HF, Li Q, Ma KL, Liu BC - PLoS ONE (2011)

ROC-curve analysis of mRNA levels.Fraction of true positive results (sensitivity) and false positive results (1-specificity) for mRNA levels of synaptopodin, CD2-AP, α-actin4, podocin, and podocalyxin as predictors of DN. The calculated area under the curve was 0.726 for synaptopodin mRNA levels (95% confidence interval 0.589 to 0.864), 0.671 for CD2-AP mRNA levels (95% confidence interval 0.53 to 0.811), 0.725 for α-actin4 mRNA levels (95% confidence interval 0.582 to 0.867), 0.753 for podocalyxin mRNA levels (95% confidence interval 0.623 to 0.883), and 0.706 for podocin mRNA levels (95% confidence interval 0.559 to 0.853). A value of 0.5 is no better than that expected by chance (the  hypothesis), and a value of 1.0 reflects a perfect indicator.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3105067&req=5

pone-0020431-g004: ROC-curve analysis of mRNA levels.Fraction of true positive results (sensitivity) and false positive results (1-specificity) for mRNA levels of synaptopodin, CD2-AP, α-actin4, podocin, and podocalyxin as predictors of DN. The calculated area under the curve was 0.726 for synaptopodin mRNA levels (95% confidence interval 0.589 to 0.864), 0.671 for CD2-AP mRNA levels (95% confidence interval 0.53 to 0.811), 0.725 for α-actin4 mRNA levels (95% confidence interval 0.582 to 0.867), 0.753 for podocalyxin mRNA levels (95% confidence interval 0.623 to 0.883), and 0.706 for podocin mRNA levels (95% confidence interval 0.559 to 0.853). A value of 0.5 is no better than that expected by chance (the hypothesis), and a value of 1.0 reflects a perfect indicator.
Mentions: ROC curves were calculated to assess the diagnostic power for each target gene in discriminating between DN patients and healthy controls. Figure 4 demonstrates the diagnostic performance of synaptopodin, podocalyxin, CD2-AP, α-actin4 and podocin in terms of AUCs when DN patients and controls were compared. As shown in Figure 4, all target genes were effectively able to discriminate between two groups, with an AUC above 0.5. The AUC was 0.753 (95% confidence interval, 0.623 to 0.883) for podocalyxin mRNA levels, which demonstrated the highest diagnostic value. The log-transformed threshold providing optimal sensitivity and specificity for podocalyxin mRNA was −3.24. Using the cutoff value of −3.24 derived from the data, podocalyxin mRNA levels predicted DN with a sensitivity of 81.4% and a specificity of 62.5% (p = 0.006).

Bottom Line: Quantification of messenger RNA (mRNA) expression in urinary sediment by real-time PCR is emerging as a noninvasive method of screening DN-associated biomarkers.Furthermore, podocalyxin mRNA was found to negatively correlate with eGFR (r = -0.349, p = 0.01).The urinary mRNA profiles of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were found to increase with the progression of DN, which suggested that quantification of podocyte-associated molecules will be useful biomarkers of DN.

View Article: PubMed Central - PubMed

Affiliation: Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, China.

ABSTRACT

Background: Podocyte injury and subsequent excretion in urine play a crucial role in the pathogenesis and progression of diabetic nephropathy (DN). Quantification of messenger RNA (mRNA) expression in urinary sediment by real-time PCR is emerging as a noninvasive method of screening DN-associated biomarkers. We hypothesized that the urinary mRNA profile of podocyte-associated molecules may provide important clinical insight into the different stages of diabetic nephropathy.

Methods: DN patients (N = 51) and healthy controls (N = 13) were enrolled in this study. DN patients were divided into a normoalbuminuria group (UAE<30 mg/g, n = 17), a microalbuminuria group (UAE 30∼300 mg/g, n = 15), and a macroalbuminuria group (UAE>300 mg/g, n = 19), according to their urinary albumin excretion (UAE). Relative mRNA abundance of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were quantified, and correlations between target mRNAs and clinical parameters were examined.

Results: The urinary mRNA levels of all genes studied were significantly higher in the DN group compared with controls (p<0.05), and mRNA levels increased with DN progression. Urinary mRNA levels of all target genes positively correlated with both UAE and BUN. The expression of podocalyxin, CD2-AP, α-actin4, and podocin mRNA correlated with serum creatinine (r = 0.457, p = 0.001; r = 0.329, p = 0.01; r = 0.286, p = 0.021; r = 0.357, p = 0.006, respectively). Furthermore, podocalyxin mRNA was found to negatively correlate with eGFR (r = -0.349, p = 0.01).

Conclusion: The urinary mRNA profiles of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were found to increase with the progression of DN, which suggested that quantification of podocyte-associated molecules will be useful biomarkers of DN.

Show MeSH
Related in: MedlinePlus