Variability in gelatinase expression in the walls of vessels used as aortocoronary conduits may impact long-term graft patency

Abstract

Background: An imbalance between the activity of matrix metalloproteinases (MMPs), particularly gelatinases, and tissue inhibitors of metalloproteinases (TIMPs) is considered as one of the mechanisms leading to aortocoronary graft failure.

Aims: We aimed to assess the variability in gelatinase expression in the walls of aortocoronary conduits and to evaluate its impact on coronary artery bypass grafting (CABG) outcomes.

Methods: The study included 101 consecutive patients (61 men and 40 women) who underwent CABG. An immunohisto­chemical analysis of MMP-2, MMP-9, TIMP-1, and TIMP-2 expression was performed on the cross-sections of the internal thoracic artery (ITA), radial artery (RA), and saphenous vein (SV). The histological findings were compared between patients with SV graft disease (SVGD[+] group) and those without occlusions in the SV (SVGD[–] group).

Results: The median MMP and TIMP expression was the weakest in the ITA wall. MMP expression was comparable between the RA and SV cross-sections, whereas TIMP expression was stronger in the RA than in the SV wall (p < 0.05). In most SV segments, but not in the arteries, immunostaining intensity for MMP was comparable to or stronger than for TIMPs. In the veins harvested from the SVGD(+) group, MMP-2 and MMP-9 tissue expression was more pronounced than in the SVGD(–) group. TIMP levels were comparable between groups.

Conclusions: Imbalance in the metalloproteinase-to-inhibitor tissue expression in the vessel wall might predispose to graft failure. A stronger expression of TIMPs than MMPs in the arterial grafts might explain favourable long-term outcomes.