Cathepsin D Activity in Urine of Children and Adolescents Correlates with Cardiovascular Risk
Authors: Cruz Nayara Azinheira Nobrega , Ronchi Fernanda Aparecida , Oliveira Lilian Caroline Gonçalves , Fernandes Fernanda Barrinha , Mill José Geraldo , Casarini Dulce Elena 
Published: June 2021

IntroductionThe RAS and KKS have a role modulating obesity and consequently can contribute to development of associated diseases, such as, diabetes mellitus, dyslipidemia, hypertension and metabolic syndrome. Preliminary studies of our group showed a correlation between diminished levels of the vasodilator peptides, Ang 1–7 and BK, and increased body mass. Also, obese and morbid obese adolescents presented higher levels of Ang I and des‐Arg9BK, a pro‐inflammatory kinin.AimWe evaluated the enzymatic activity profile of proteases involved on the biosynthesis and inactivation of RAS and KKS peptides in children and adolescents.MethodsIt is a cross‐sectional study, including 360 children and adolescents aged from 6 to 19 years. The participants were categorized into four groups according to their BMI percentile; underweight (n = 57), normal weight (n= 120), overweight (n = 120) and obese (n = 63). The urines were concentrated 10‐fold and dialyzed with TRIS – HCl pH 8 buffer. The urinary activity of ACE, ACE2, NEP and Cathepsin D were assayed. ACE activity was assessed through fluorimetric assay using the substrate Z‐Phe‐His‐Leu. To the remaining enzymes, fluorescence‐quenching peptide substrates with specific sequence were used. Additionally, assessment of cardiovascular parameters, anthropometric measurements, lipids profile and biochemical parameters were performed.ResultsCathepsin D has reduced activity in the overweight group when compared to the normal weight group (0,027 μM/min/mg de creatinine vs 0,098 μM/min/mg de creatinine, p < 0,01). Waist‐height‐ratio was used to assess cardiovascular risk, cathepsin D activity was diminished in the high‐risk group in comparison to control (0,028 μM/min/mg de creatinine vs 0,095 μM/min/mg de creatinine, p <0,01). According to Spearman correlation test, cathepsin Dhas a moderate negative correlation with waist circumference (cm), waist‐to‐hip ratio, waist‐to‐height ratio, fat mass (Kg), percentage of fat (%) and IMC (Kg/m2). The ACE activity presents moderated positive correlation with VLDL‐C levels and negative correlation with HDL‐C.ConclusionIn physiological conditions it is improbable that impaired cathepsin D activity alone contributes significantly to the formation of RAS angiotensin I peptide. However, considering the clearance of cathepsin D as a mechanism to keep its levels within a narrow range in circulation, this data can support that cathepsin D accumulates in the blood of overweight and high cardiovascular risk children. In relation to the remaining enzymes evaluated, there were not differences statistically significant between the groups. However, they present different enzymatic profile and can contribute to differences on levels of RAS and KKS peptides. Therefore, further evaluation of cathepsin D expression in urine and blood, as well as, measurement of RAS and KKS peptides levels are necessary to effective conclusions.Support or Funding InformationCAPES and FAPESPThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.