Heart failure lowers plasma DPP4 enzyme activity in dogs

Abstract

BACKGROUND: In congestive heart failure (HF), plasma B-type natriuretic peptide (BNP) seems devoid of biological effectiveness. BNP(1-32) could be truncated into BNP(3-32) by dipeptidyl peptidase IV (DPP4), and BNP(3-32) has reduced biological activities. HYPOTHESIS: Increased DPP4 activity is associated with pathophysiology of HF. ANIMALS: One hundred twenty-eight client-owned dogs and 9 experimental Beagles from the Clinical Veterinary Unit of the University of Li&#xe8;ge. METHODS: We prospectively measured plasma DPP4 activity in 5 groups of dogs: normal growing dogs (n = 21), normal adult dogs (n = 60), healthy Beagle (n = 9), dogs with myxomatous mitral valve disease (n = 35), and dogs with dilated cardiomyopathy (n = 12). The final diagnosis and the severity of HF were determined by Doppler echocardiography. Plasma DPP4 activity was measured kinetically by a fluorimetric method. RESULTS: In growing dogs, DPP4 activity was higher than in adults (P < .001) and inversely correlated with age (r = -0.57, P < .01). In adults, DPP4 activity increased linearly with body weight (r = 0.39, P < .01), but there was no influence of age or sex. No effect of the circadian rhythm was noted. DPP4 activity was significantly higher in HF ISACHC I (16.3 &#xb1; 1.14 U/L) compared with healthy adults (12.4 &#xb1; 0.65 U/L, P < .05) and HF ISACHC III (11.0 &#xb1; 1.50 U/L, P < .05). Mean DPP4 activity in ISACHC II was 15.1 &#xb1; 1.4 U/L. CONCLUSION AND CLINICAL IMPORTANCE: We did not find evidence that plasma DPP4 activity is responsible for the "BNP resistance" in overt congestive HF, but it may be implicated in early stages.