EGFR and MMP-9 are associated with neointimal hyperplasia in systemic-to-pulmonary shunts in children with complex cyanotic heart disease

Abstract INTRODUCTION: Systemic-to-pulmonary (SP) shunt malfunction contributes to morbidity in infants with single ventricle physiology after palliative procedure. Neointimal hyperplasia might play a role in the pathogenesis, increasing risk for shunt obstruction. Epidermal growth factor receptor (EGFR) and matrix-metalloproteinase 9 (MMP-9) are described as contributors for neointimal formation in other diseases. Aim of this study was to quantify EGFR and MMP-9 in SP shunts by immunohistochemistry and to identify risk alleles in genes encoding related proteins. METHODS: Immunohistochemistry was performed with anti-EGFR and anti-MMP-9 on 31 SP shunts removed at follow-up palliative or corrective procedure at the time of surgery. Whole-genome single nucleotide polymorphisms genotyping was performed on DNA extracted from patients´ blood samples and allele frequencies were compared between the group of patients with shunts displaying severe stenosis (≥40% shunt stenosis) and the remaining group. RESULTS: In immunohistochemistry we mainly detected EGFR and MMP-9in the luminal area of the shunt. Cross sectional area of EGFR and MMP-9 measured in median 0.19 mm2(IQR, 0.1-0.3 mm2) and 0.04 mm2 (IQR, 0.03-0.09 mm2) respectively, and correlated positively with the area of neointimal measured on histology (r=0.729, p<0.001 and r=0.0479, p=0.018). Certain alleles in epidermal growth factor (EGF) and tissue inhibitor of metalloproteinases-1 (TIMP-1) were associated with increased stenosis and neointimal hyperplasia within shunts. CONCLUSION: EGFR and MMP-9 contribute to neointimal proliferation in SP shunts of children with complex cyanotic heart disease. SP shunts from patients carrying certain risk alleles in the genes encoding for EGF and TIMP-1 displayed increased neointima.