MR-PROADM PLASMA LEVELS ARE INCREASED IN OBESE ADOLESCENTS

Background: Studies on adipokines and other biomarkers of obesity have became important in obesity research and recently also adrenomedullin (ADM) was defined as a new member of adipokine family. The ADM precursor gene, (preproADM) is transcriptionally induced by insulin, hypoxia and inflammatory stimuli and acute hyperinsulinemia was associated with increased circulating plasma ADM levels in diabetic patients or in uncomplicated obese subjects. It has been shown that ADM can be beneficial in treating some diseases such as hypertension, cardiac hypertrophy, cerebral ischemia. Thus, ADM secreted by adipocytes, through its vasodilator and antioxidant actions, might be protective against cardiovascular complications induced by metabolic syndrome. To date, little is known on the impact of obesity on plasma ADM and no data are available for this peptide in childhood obesity. Aim of the present study was to assess plasma MR-proADM levels in obese adolescents compared with normal weight subjects and its relation with weight and BMI. Methods: Plasma MR-proADM was measured in 30 healthy adolescents (BMI=20.9±0.6) and in 51 age- matched obese adolescents (BMI=29.6±0.6) by a Time-Resolved Amplified Cryptate Emission (TRACCE) technology assay, using a kit designed for automated sandwich immunofluorescent assay of MR- proADM (KRIPTOR: BRAHMS AG). Results: Plasma MR-proADM levels resulted significantly higher in obese than in healthy adolescents (MR-proADM:0.33±0.1 vs 0.40±0.1 pmol/L, p<0.0001). Circulating MR-proADM levels correlated to body weight (r= 0.35, p=0.002), BMI (r= 0.53, p<0.0001) and with fat mass (r=0.51, p<0.0001) while no correlation was observed with lean mass (r=0.05, p=0.6). A significant correlation was also observed with insulin levels (r=0.3, p=0.007) and with systolic blood pressure (r=25, p=0.02). Plasma MR-proADM levels were not related to gender or age. Conclusions: Our results showed, for the first time, an increase in circulating MR-proADM plasma levels in obese adolescents confirming previous data observed in adults. The pathophysiological role of adipose tissues-secreted ADM is still speculative and further studies are necessary to clarify its effect, particularly in obesity. If the hypothesis of its beneficial effect is confirmed, then ADM might be useful in developing drugs to prevent cardiovascular complications associated with obesity.