Correlation between the Expression of Somatic ACE (190KDa) and of its Soluble N‐Domain Isoforms (90KDa and 65KDa) with Different Nutritional Status and Cardiovascular Risk Profile
Authors: Oliveira Lilian Caroline Gonçalves , Cruz Nayara Azinheira Nobrega , Fernandes Fernanda Barrinha , Mill José Geraldo , Casarini Dulce Elena 
Published: April 2020

ACE has been pointed out to be involved in the physiopathology of several diseases including hypertension, diabetes, obesity and metabolic syndrome. The somatic ACE weights from 130 to 190 KDa and presents two domains, N‐domain and C‐domain. Whilst the somatic form of ACE was already identified in a considerable range of tissues, the testicular form of ACE is exclusively found on testis. Two soluble isoforms of N‐domain are naturally present in the organism and have been described in ileal fluid and urine of humans, one weighting 65KDa and the other 90KDa. Studies have supported that the 90KDa isoform of the N‐domain of somatic ACE is a biomarker for hypertension, pre‐eclampsia and inflammation.

The aim of this study was to evaluate the expression of somatic ACE (190KDa) and of its soluble N‐domain isoforms (90KDa and 65KDa) in urine of children and adolescents with different nutritional status and cardiovascular risk profile.

The participants aged from 6 to 19 years were classified into four groups according to their BMI percentile; underweight (n = 51), normal weight (n = 53), overweight (n =53) and obese (n = 49). Waist‐height‐ratio (WHtR) was used to assess cardiovascular risk profile dividing the participants into normal risk (n = 105) and high risk (n = 101). The urines were concentrated 10‐fold and dialyzed with Tris‐HCl pH 8 and pure water. Then, we performed western blot analysis using 50μg of lyophilized urinary protein for molecular weight control. ACE expression was proved against the polyclonal antibody Y1. Protein detection was performed based on chemiluminescent method and the analysis was done in the Image Lab® (BioRad) software utilizing total protein stain for normalization.

Expression of ACE is augmented in obese children when compared with normal weight children (0.09 arbitrary unit vs 0.53 arbitrary unit, p = 0,04). The higher cardiovascular risk group also presented increased expression of ACE (0.27 arbitrary unit vs 0.09 arbitrary unit, p=0.046). The N‐domain isoform of 90KDa is more frequently found in the high cardiovascular risk children (p = 0.02). Additionally, according to Spearman correlation test, the expression of 90KDa N‐domain isoform correlates positively with waist circumference (cm), WHtR, BMI percentile and Z‐score of BMI.

Obesity is a major factor to cardiovascular disease. Increased ACE expression in obese children contributes to higher cardiovascular risk once this enzyme biosynthesizes Angiotensin II which promotes blood pressure increase, sympathetic nervous system activation and release of glucocorticoids from adrenal gland. Accordingly, ACE expression is also augmented in children with high cardiovascular risk. Presence of 90 KDa isoform of N‐domain in urine of children and adolescents is a biomarker of poor prognostic for cardiovascular disease in childhood obesity.

Support or Funding Information

FAPESP, CAPES and CNPq.