Interleukin 37; a possible marker of arterial stiffness in Behçet's disease.

BACKGROUND

Interleukin 37 (IL-37) is an anti-inflammatory cytokine previously studied in Behçet's disease (BD) and atherosclerosis. However, little is known about its relation to macro and microcirculations in BD. Previous studies relied mainly on common carotid artery (CCA) intima-media thickness (IMT) and ankle brachial index (ABI) to study atherosclerosis in BD with conflicting results. This study evaluated flow parameters of CCA, ABI and nailfold videocapillaroscopy in relation to serum IL-37 in BD.

METHODS

Forty BD patients and 30 healthy controls were included. IMT, peak-systolic, end-diastolic velocities, resistivity index of CCA and ABI were measured by duplex ultrasound. Capillary loop, length, diameter and morphology were recorded by nailfold videocapillaroscopy. Serum IL-37 levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared to controls, patients had higher mean CCA IMT (p < 0.0001), resistivity index (p < 0.001) and peak-systolic velocity (p=0.09) and lower mean CCA end-diastolic velocity (p=0.002), capillary loop, length, arterial, venous limbs diameter and serum IL-37 (p < 0.001). Patients with ABI ≥ 1.4 "indicating stiff arteries" had higher serum IL-37 (p < 0.05 on left, p>0.05 right sides). Serum IL-37 correlated negatively with left CCA end-diastolic velocity "denoting atherosclerosis" and positively with left posterior tibial artery ABI and CRP (p < 0.03) "denoting inflammation". Multiple regression analysis showed only association with left CCA end-diastolic velocity.

CONCLUSIONS

IL-37 may be related to arterial stiffness in BD and could be used as a possible marker of arteriosclerosis in the disease for further investigations. Changes of CCA peak-systolic, end-diastolic velocities, resistivity index and IMT refer to increased atherosclerosis in larger elastic arteries. In smaller muscular "crural" arteries, vasculitis with possible medial disease may be more evident.