title: Different Susceptibility of B-Type Natriuretic Peptide (BNP) and BNP Precursor (proBNP) to Cleavage by Neprilysin: The N-Terminal Part Does Matter.
abstract: BACKGROUND
  Protease neprilysin is known to be responsible for the degradation of natriuretic peptides. A recent heart failure (HF) drug, LCZ696 (Entresto(TM)), that combines a neprilysin inhibitor and an angiotensin II receptor inhibitor was suggested to augment circulating B-type natriuretic peptide (BNP) concentrations, making the results of BNP measurements diagnostically ambiguous. Because the main form of measured BNP in HF patients is represented by its uncleaved precursor, proBNP, it is important to know the susceptibility of proBNP to cleavage by neprilysin.
  
  
  METHODS
  BNP 1-32 and nonglycosylated and glycosylated forms of proBNP 1-108 were incubated with neprilysin for different time periods. BNP immunoreactivity was analyzed using 2 sandwich immunoassays: one utilizing monoclonal antibody (mAb) KY-BNP-II (epitope 14-21) as capture with mAb 50E1 (epitope 26-32) for detection and a single-epitope sandwich BNP (SES-BNP) immunoassay specific to the epitope 11-17. Mass-spectrometry was applied to determine the sites of BNP cleavage.
  
  
  RESULTS
  In contrast to BNP, both forms of proBNP were resistant to degradation by neprilysin. The SES-BNP assay was much less susceptible to the BNP cleavage by neprilysin compared with the immunoassay utilizing antibodies specific to the region 14-21, comprising the site Arg17-Ile18, known as the site of BNP cleavage by neprilysin.
  
  
  CONCLUSIONS
  These findings suggest that modulation of neprilysin activity by specific inhibitors may not greatly influence the circulating concentrations of immunoreactive BNP, mostly represented in HF by proBNP, which is not susceptible to neprilysin. The different susceptibility of the BNP regions to neprilysin-dependent degradation highlights the importance of the choice of epitopes for reliable BNP immunodetection.
authors: HyTest Ltd., Turku, Finland; alexander.semenov@hytest.fi.
authors: Alexander G
authors: AG
authors: Semenov
authors: HyTest Ltd., Turku, Finland; School of Biology, Moscow State University, Moscow, Russia.
authors: Alexey G
authors: AG
authors: Katrukha
mesh_terms: D000613:Aminobutyrates / Q000494:pharmacology / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001713:Biphenyl Compounds; D004338:Drug Combinations; D000939:Epitopes / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D006031:Glycosylation; D006333:Heart Failure / Q000097:blood / Q000188:drug therapy; D006801:Humans; D007118:Immunoassay; D057230:Limit of Detection; D020097:Natriuretic Peptide, Brain / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D015260:Neprilysin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010446:Peptide Fragments / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D011498:Protein Precursors / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D059748:Proteolysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013777:Tetrazoles / Q000494:pharmacology / Q000627:therapeutic use; D000068756:Valsartan
chemical_list: D000613:Aminobutyrates; D000911:Antibodies, Monoclonal; D001713:Biphenyl Compounds; D004338:Drug Combinations; D000939:Epitopes; D010446:Peptide Fragments; C524086:Pro-BNP1-108; D011498:Protein Precursors; D013777:Tetrazoles; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D000068756:Valsartan; D015260:Neprilysin; C549068:sacubitril and valsartan sodium hydrate drug combination