title: Monitoring of dipeptidyl peptidase-IV (DPP-IV) activity in patients with mucopolysaccharidoses types I and II on enzyme replacement therapy - Results of a pilot study.
abstract: OBJECTIVE
  Mucopolysaccharidoses (MPSs) are a group of rare, inherited metabolic disorders which result from the lack of one of the lysosomal enzymes responsible for the degradation of glycosaminoglycans. Early recognition of MPS is important as it enables prompt implementation of enzyme replacement therapy (ERT). Dipeptidyl peptidase-IV (DPP-IV) is a ubiquitous ectopeptidase which activity has been associated with the cell surface protein CD26. Our aims were to investigate plasma DPP-IV activity in untreated patients with MPS type II in comparison to control individuals and to evaluate changes of DPP-IV during ERT in MPS I or II patients.
  
  
  METHODS
  One MPS I and five MPS II patients were treated with ERT for up to 19 months. DPP-IV activity was measured in plasma with a colorimetric method using Gly-Pro-p-nitroanilide as a substrate. The reference intervals were observed in 17 healthy donors and in 9 MPS II individuals before ERT implementation.
  
  
  RESULTS
  DPP-IV activity ranged from 557 to 1959 nmol/ml/h (median and interquartile range: 1453 [955– 1554], n = 17) in plasma of control samples. In 9 untreated MPS II individuals, DPP-IV activity was higher and ranged from 2565 to 5968 nmol/ml/h (median and interquartile range: 4458 [4031–5161]). In 6 MPS patients receiving ERT, DPP-IV activity ranged from 2984 to 8628 nmol/ml/h. No declining tendency was observed during the treatment.
  
  
  CONCLUSIONS
  DPP-IV activity is a good, newa nd valuable biomarker distinguishing between MPS and healthy individuals. However, it is not a useful marker of treatment efficacy and is unsuitable for monitoring.
authors.affiliation: Institute of Psychiatry and Neurology, Department of Genetics, Warsaw, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Hetmańczyk
authors.affiliation: Institute of Psychiatry and Neurology, Department of Genetics, Warsaw, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Bednarska-Makaruk
authors.affiliation: The Children's Teaching Hospital in Białystok, The Department of Pediatrics and Developmental Disorders of Children and Adolescents, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Kierus
authors.affiliation: Provincial United Hospital in Toruń, Department of Pediatrics, Endocrinology and Neurology, Poland.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Murawska-Izdebska
authors.affiliation: The Children's Memorial Health Institute, Department of Medical Genetics, Warsaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Piekutowska-Abramczuk
authors.affiliation: Jagiellonian University, Collegium Medicum, Department of Pediatrics, Cracow, Poland.
authors.forename: Bożena
authors.initials: B
authors.lastname: Pilch
authors.affiliation: The Children's Memorial Health Institute in Warsaw, Department of Pediatrics, Nutrition and Metabolic Diseases, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Tylki-Szymańska
authors.affiliation: Institute of Psychiatry and Neurology, Department of Genetics, Warsaw, Poland. Electronic address: alugipin@yahoo.com.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Ługowska
mesh_terms: D003124:Colorimetry; D018819:Dipeptidyl Peptidase 4 / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D056947:Enzyme Replacement Therapy; D006801:Humans; D008059:Mucopolysaccharidosis I / Q000188:drug therapy / Q000201:enzymology*; D016532:Mucopolysaccharidosis II / Q000188:drug therapy / Q000201:enzymology*; D010865:Pilot Projects
chemical_list: D018819:Dipeptidyl Peptidase 4
keywords: Biomarker; DPP-IV; Enzyme replacement therapy; Mucopolysaccharidosis type I; Mucopolysaccharidosis type II