Urinary VEGFA and Renal Pathology Evaluated for IgA Nephropathy Patients

Immunoglobulin A (IgA) nephropathy (IgAN) is the most common primary glomerulonephritis and is the leading cause of end-stage renal disease (ESRD) in China. Renal biopsy remains the golden standard for diagnosing and monitoring IgA nephropathy (IgAN).

Vascular endothelial growth factor-A (VEGFA) is an essential angiogenic cytokine and found to be crucial for the survival, differentiation and structure maintaining of these glomerular cells. VEGFA is therefore, pivotal for maintaining the glomerular filtration barrier function. The relationship of urinary and renal VEGFA in IgAN patients are still not clear.

Nephrologists at the Sun Yat-sen University (Guangzhou, China) recruited a total of 85 IgAN patients and 71 healthy controls without microscopic hematuria, proteinuria, hepatic disease and with normal serum creatinine. Samples of IgAN patients were obtained at the day of renal biopsy. Serum and morning urine collected from each subject were transferred to a separate vial after centrifuge and stored at −80 ℃ until assayed.

Serum levels of VEGFA were measured by ELH-VEGF-1 ELISA (RayBiotech, Peachtree Corners, GA, USA), and urine VEGFA levels were measured by ELISA from R&D Systems (Minneapolis, MN, USA). Absorbance was measured at 450 nm using the SpectraMax Plus 384 Microplate reader (Molecular Devices, San Jose, CA, USA). Renal biopsies of 27 IgAN patients were randomly selected from enrolled 85 IgAN patients and used for VEGFA testing by immunohistochemistry analysis. The expression levels of VEGFA and Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were quantified by real-time PCR using Taqman with a fluorescence detection monitor 7900 Real-time PCR system (Applied Biosystems, Waltham, MA, USA).

The investigators reported that compared with healthy controls, urinary VEGFA level was elevated in IgAN patients (76.19 ± 63.67 pg/mg Cr versus 146.67 ± 232.71 pg/mg Cr), and not correlated with serum VEGFA level. Baseline urinary VEGFA was significantly associated with gender and tubular atrophy/interstitial fibrosis by stepwise multivariate regression analysis. Urinary VEGFA was higher in male patients accompanied with higher serum creatinine, larger proportion of hypertension and recurrent hematuria than in female patients. In the kidney of IgAN patients, VEGFA were robustly expressed in the parietal epithelial cells, podocytes, mesangial cells and tubular epithelial cells. After a follow-up duration of 38.53 ± 27.14 months, IgAN patients with higher urinary VEGFA level were found to have a poorer renal outcome of renal replacement therapy.

The authors concluded that increased urinary VEGFA might reflect certain renal pathology and, although not fully specific, still could be served as a valuable noninvasive indicator in predicting renal progression of IgAN. The study was published on September 8, 2021 in the Journal of Clinical Laboratory Analysis.

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