Abstract Body: Background and aim: The Renin Angiotensin System (RAS) has an important role in the pathophysiology of primary nephrotic syndrome (NS). It was previously found that urinary levels of angiotensin converting enzyme 2 (ACE2) are reduced in patients with NS in comparison to health controls. The aim of this study was to measure the novel angiotensin peptide, Alamandine-(1-5), in plasma samples of patients with primary NS and to compare with sex and age-matched controls.
Methods: Blood samples of pediatric patients with primary NS (n=11) and of sex and age-matched health controls (n=11) were collected in sterile tubes with 7.5% (w/v) EDTA. After plasma separation and purification by solid phase extraction, the circulating levels of Alamandine and of Alamandine-(1-5) were measured by Mass Spectrometry using multiple reaction monitoring on an ACQUITY I-Class UPLC system coupled to electrospray ionization (ESI) tandem mass spectrometry (LC-ESI-MS/MS Xevo TQ-S). Data were compared between patients and controls and associated with laboratory findings. Continuous variables were presented as mean ± standard error of the mean.
Results: A total of 11 patients (7 males) with NS with mean age of 10.65±3.66 were compared to 11 controls (6 males) and with 10.86±4.35 years. In terms of disease response, 5 patients were in partial remission, 5 patients in total remission and only 1 patient was in disease relapse. All patients have normal renal function. Plasma levels of Alamandine-(1-5) were significantly higher in patients when compared to controls (28.03±7.54 vs. 10.68±3.02 pg.mL-1 in controls). Despite a mild decrease in patients, plasma levels of Alamandine did not differ between groups (19.54±6.33 vs 26.09±6.12 pg.mL-1 in controls). No correlations were found between RAS molecules and proteinuria and with the medications in use. However, Alamandine-(1-5) negatively correlated with plasma levels of albumin (r= -0.695; p=0.038). In addition, Alamandine negatively correlated with total cholesterol (r=-0.700; p = 0.036), LDL (r=-0.800; p=0.004), and HDL (r = -0.762; p = 0.038).
Conclusion: The novel RAS peptide Alamandine-(1-5) is significantly increased in primary NS and inversely correlated with plasma albumin levels. These findings suggest a potential role of Alamandine-(1-5) in NS