The viral anti-inflammatory chemokine-binding protein M-T7 reduces intimal hyperplasia after vascular injury

Abstract

Chemokines and IFN-γ function as central regulators of inflammatory responses to vascular injury. Both classes of cytokines are upregulated during restenosis, a response to vascular injury that leads to recurrent atherosclerotic plaque growth, but the relative impact of each class of cytokines remains undetermined. M-T7 is a secreted myxoma viral immunomodulatory glycoprotein that functions both as a species-specific inhibitor of rabbit IFN-γ and as a chemokine-binding protein, interacting with a wide range of C, C-C, and C-X-C chemokines in a species-nonspecific fashion. We wished to (a) assess the efficacy of purified M-T7 protein in inhibiting intimal hyperplasia after angioplasty injury and (b) exploit unique species-specific functions of M-T7 in order to judge the relative importance of each cytokine class on plaque growth. Anesthetized New Zealand white rabbits and Sprague-Dawley rats received either M-T7 or control at the time of arterial angioplasty injury. Histological analysis at 28 days demonstrated significant reductions in intimal hyperplasia with M-T7 treatment in both models, with an associated early inhibition of inflammatory cell invasion. Purified M-T7 protein inhibits intimal hyperplasia after angioplasty injury in a species-nonspecific fashion, thus implicating the chemokine-binding activity as more critical for prevention of plaque growth after vascular injury.

Inhibition of Intimal Hyperplasia in Transgenic Mice Conditionally Expressing the Chemokine-Binding Protein M3

“…Similarly, intravenous administration of M-T7, a chemokine-binding protein produced by the myxoma virus, resulted in an Ϸ80% reduction in a rabbit model of intimal hyperplasia. 48 These studies support a role for chemokines in mediating intimal hyperplasia. Both M3 and M-T7 bind to CCL2 (MCP-1) and recent data suggests that M3 masks the binding site of CCL2 (MCP-1) 24 and may thus inhibit binding to its receptor, CCR2.…”

Comparative Analysis of Plaque Growth after Arterial Stent Implant with Anti-Inflammatory Chemokine and Serine Protease Inhibitors Treatment

“…Harvested arterial sections were processed and stained with hematoxylin and eosin (H & E) or Masson's trichrome stains as previously described [25][26][27][28][29][30][31]33]. Plaque area, was measured by morphometric analysis using an Olympus CCD color video camera attached to an Olympus microscope, and the ImagePro application program calibrated to the microscope objective [26][27][28][29][30][31]33].…”

“…Plaque area, was measured by morphometric analysis using an Olympus CCD color video camera attached to an Olympus microscope, and the ImagePro application program calibrated to the microscope objective [26][27][28][29][30][31]33]. Both the mean total cross-sectional intimal area and the mean intimal thickness after normalized to the medial thickness were calculated for each arterial section.…”

“…These inflammatory moderators function at femptomolar to picomolar concentrations when secreted by the originating viruses [23,24]. Two such proteins, Serp-1 that inhibits uPA/uPAR [23][24][25][26][27][28] and M-T7 [26,[29][30][31] that blocks the C terminal GAG binding domain of C, CC and CXC class chemokines [26,[29][30][31] have been purified individually and studied as anti-inflammatory reagents in a wide range of animal models with demonstrated reduction in inflammatory cell invasion and plaque growth. One protein, Serp-1 has been successfully tested in clinical trial for treatment of patients with unstable coronary syndromes (Unstable angina and NSTEMI) who have received stent implants [26,32].…”

“…M-T1 from vMyxlacT1gpt infected BGMK cell cultures as previously described [26,29,31]. Concentrated supernatants were fractionated by Mono QHR5/5 anion exchange chromatography followed by gel filtration chromatography using a HiLoadSuperdex 200 column (AmershamPahrmacia Biotech Inc.).…”