Associations of plasma PAPP-A2 and genetic variations with salt sensitivity, blood pressure changes and hypertension incidence in Chinese adults.

OBJECTIVE: Pregnancy-associated plasma protein-A2 (PAPP-A2) is the homolog of PAPP-A in the vertebrate genome and its role in protecting against salt-induced hypertension in salt-sensitive rats has been confirmed. We sought to examine the associations of plasma PAPP-A2 levels and its genetic variants with salt sensitivity, blood pressure (BP) changes and hypertension incidence in humans.
METHODS: Eighty participants (18-65 years old) sequentially consuming a usual diet, a 7-day low-salt diet (3.0 g/day) and a 7-day high-salt diet (18 g/day). In addition, we studied participants of the original Baoji Salt-Sensitive Study, recruited from 124 families in Northern China in 2004 who received the same salt intake intervention, and evaluated them for the development of hypertension over 14 years.
RESULTS: The plasma PAPPA2 levels significantly decreased with the change from baseline to a low-salt diet and decreased further when converting from the low-salt to high-salt diet. SNP rs12042763 in the PAPP-A2 gene was significantly associated with systolic BP responses to both low-salt and high-salt diet while SNP rs2861813 showed a significant association with the changes in SBP and pulse pressure at 14-year follow-up. Additionally, SNPs rs2294654 and rs718067 demonstrated a significant association with the incidence of hypertension over the 14-year follow-up. Finally, the gene-based analysis found that Pappa2 was significantly associated with longitudinal SBP changes and the incidence of hypertension over the 14-year follow-up.
CONCLUSIONS: This study shows that dietary salt intake affects plasma PAPP-A2 levels and that PAPP-A2 may play a role in salt sensitivity, BP progression and development of hypertension in the Chinese populations.