C-type natriuretic peptide plasma levels and mRNA expression in adolescents with of endothelial dysfunction

Background-aim C-type natriuretic peptide (CNP) was recently indicated as important natural regulator of adipogenesis involved especially in pediatric obesity. While CNP plasmatic levels are known in childhood, no data are available on its expression. Our aim was to evaluate both CNP plasma levels and CNP-system expression in normal-weight (N) and obese (O) adolescent. Methods Twenty-four N and sixteen O were studied; endothelial function was assessed by measuring reactive hyperemia index (RHI). Results plasma CNP resulted significantly lower in O than in N (Pb0.0001), while CNP/NPR-B/NPR-C mRNA expression was similar in N and O. Circulating C-Reactive Protein was higher in O than in N conversely RHI was lower in O than in N (Pb0.0001, respectively) and correlated with plasma CNP in the whole population (P=0.0003). Dividing subjects according to the median of RHI (>=1.9 or b1.9), irrespective of the presence/absence of obesity, CNP levels resulted higher in Group 1 than in Group 2 (P=0.0014), while CNP mRNA expression was surprisingly higher in Group 2 than in Group 1 (P=0.025). NPR-B mRNA resulted similar in both Groups while NPR- C was higher in Group 2 (P=0.026). Conclusions Our data suggest a different trend in CNP plasma levels and mRNA expression, assessed for the first time in childhood, that could reflect changes occurring both at CNP transcriptional level, in activated leucocytes due to inflammation, and at blood levels, due to CNP paracrine/autocrine activities. The regulation of CNP-system transcription may represent an interesting area for investigating new drugs in diseases characterized by endothelial dysfunction.