title: Decreased soluble dipeptidyl peptidase IV activity as a potential serum biomarker for COPD.
abstract: OBJECTIVE
  The objective of this study was to measure soluble dipeptidyl peptidase IV (sDPPIV) activity in sera of patients with stable chronic obstructive pulmonary disease (COPD) in comparison to healthy controls. The main goal was to assess changes in the enzyme activity in relation to severity of the disease, age and smoking history and to evaluate diagnostic accuracy for prediction of COPD by level of serum sDPPIV activity.
  
  
  METHODS
  The study included 106 patients with stable COPD (GOLD II-GOLD IV stages) and 38 healthy controls. Serum sDPPIV activity as well as some inflammatory markers (CRP, total and differential leukocyte counts) was measured. Multivariate logistic regression models were applied to analyze association of sDPPIV activity and inflammatory markers in risk estimation for COPD development.
  
  
  RESULTS
  sDPPIV activity in COPD patients was significantly reduced when compared to healthy controls. Decrease was observed already in GOLD II stage. Age and smoking history did not influence sDPPIV activity. Very good diagnostic accuracy (AUC=0.833; sensitivity and specificity of 85.7% and 78.9%, respectively) for GOLD II and good diagnostic accuracy (AUC=0.801; sensitivity and specificity of 65.1% and 86.8%, respectively) for total cohort of COPD patients were found. The multivariate logistic regression model showed that the use of sDPPIV in combination with CRP and lymphocyte proportion improved diagnostic strength and gave an AUC of 0.933.
  
  
  CONCLUSIONS
  sDPPIV activity is decreased in COPD patients as early as in GOLD II stage. Very good diagnostic accuracy of sDPPIV activity suggests it as a candidate biomarker for early diagnosis of COPD.
authors.affiliation: University of Zagreb, Faculty of Pharmacy and Biochemistry, Department of Medical Biochemistry and Hematology, Domagojeva 2, HR-10000 Zagreb, Croatia. asomborac@pharma.hr
authors.forename: Anita
authors.initials: A
authors.lastname: Somborac-Bačura
authors.forename: Sunčica
authors.initials: S
authors.lastname: Buljević
authors.forename: Lada
authors.initials: L
authors.lastname: Rumora
authors.forename: Ognjen
authors.initials: O
authors.lastname: Čulić
authors.forename: Dijana
authors.initials: D
authors.lastname: Detel
authors.forename: Dolores
authors.initials: D
authors.lastname: Pancirov
authors.forename: Sanja
authors.initials: S
authors.lastname: Popović-Grle
authors.forename: Jadranka
authors.initials: J
authors.lastname: Varljen
authors.forename: Ivana
authors.initials: I
authors.lastname: Čepelak
authors.forename: Tihana
authors.initials: T
authors.lastname: Žanić-Grubišić
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D018819:Dipeptidyl Peptidase 4 / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000175:diagnosis / Q000201:enzymology; D012372:ROC Curve; D012907:Smoking / Q000097:blood
chemical_list: D015415:Biomarkers; C042807:DPP4 protein, human; D018819:Dipeptidyl Peptidase 4