Background: Paraoxonase 1 (PON1) is an extracellular enzyme, which in the gastrointestinal tract may act as a local detoxifier, antioxidant, immunomodulator, and/or quorum-quenching factor. There are no data on PON1 activity in Crohn's disease (CD).
Methods: PON1 phenotype and activity were determined spectrophotometrically in 52 subjects with CD, 67 with ulcerative colitis (UC), and 99 healthy individuals, and related to lipid peroxidation and disease phenotype, clinical and biochemical activity, and therapeutic strategy. Diagnostic utility of PON1 was evaluated by ROC analysis and compared with C-reactive protein (CRP).
Results: In comparison with controls (166 U), PON1 was reduced only in active CD (110 U, P < 0.0001) and UC (126 U, P < 0.0001), and correlated with disease activity (r = -0.47, P = 0.001 in CD and r = -0.50, P < 0.001 in UC). PON1 significantly correlated with erythrocyte sedimentation rate (ESR) (r = -0.36), platelets (r = -0.35), interleukin-6 (r = -0.45), hemoglobin (r = 0.29), transferrin (r = 0.46), albumin (r = 0.60) in CD, and CRP (r = -0.29), ESR (r = -0.37), platelets (r = -0.43), leukocytes (r = -0.50), interleukin-6 (r = -0.45), hemoglobin (r = 0.34), transferrin (r = 0.54), and albumin (r = 0.50) in UC. PON1 correlated positively with lipids but not with their peroxidation markers (thiobarbituric acid-reactive substances, lipid hydroperoxides, ox-LDL, and ox-LDL autoantibodies). PON1 phenotype B (protective against IBD) tended to be less frequent in IBD patients than controls, and associated with lower concentration of inflammatory indices. PON1 was a poorer indicator of CD or UC than CRP.
Conclusions: PON1 was reduced in IBD, despite treatment with antioxidant 5'-aminosalicylate derivatives. PON1 reflected disease activity, inflammation severity, and anemia but not lipid peroxidation. The diagnostic power of PON1 was insufficient for its clinical application.