251 Pushpakom, et al: COL15 polymorphisms in SSc Personal non-commercial use only. The Journal of Rheumatology Copyright © 2008. All rights reserved. Polymorphisms in COL15 Gene Are Not Associated with Systemic Sclerosis SUDEEP P. PUSHPAKOM,ARIANE L. HERRICK, SHANT KUMAR, and JANE WORTHINGTON ABSTRACT. Objective. Systemic sclerosis (SSc) is marked by microvascular abnormalities leading to ischemic fea- tures such as Raynaud’s phenomenon and fingertip ulcers. Digital ischemia in turn results in hypoxia, which is expected to drive compensatory angiogenesis; however, this phenomenon is deregulated in SSc. Vascular basement membrane (VBM) that consists of type IV, XV, and XVIII collagens supports the growth and survival of vascular endothelial cells and plays a key role in regulating angiogenesis. Recent gene expression analyses of skin tissue and dermal fibroblasts from patients with SSc revealed COL15 to be one of the significantly differentially regulated genes. We undertook an association study to explore the role of COL15 single-nucleotide polymorphisms (SNP) in SSc disease development. Methods. Eleven SNP across COL15 were genotyped in a cohort of 175 UK Caucasian patients with SSc and 190 population-matched unrelated healthy subjects using 2 methods: TaqMan and SNaPshot. Statistical analysis was performed by Pearson’s chi-square test and HelixTree software was utilized for haplotype analysis. Results. No difference in genotype or allele frequencies were detected between patients with SSc and controls. None of the haplotype frequencies were found to differ between patients and controls. Conclusion. Failure to detect an association may reflect a true lack of association or could be a false- negative result arising as a result of low power of the study. Our study had sufficient power to detect an effect size of 2.1 (p = 0.05); however, larger patient cohorts may be needed for exclusion of COL15 from a possible candidacy in SSc. (First Release Jan 15 2008; J Rheumatol 2008;35:251–3) Key Indexing Terms: SYSTEMIC SCLEROSIS SCLERODERMA GENE POLYMORPHISMS COL15 VASCULAR BASEMENT MEMBRANE ANGIOGENESIS From the Department of Pathology and ARC Epidemiology Unit, University of Manchester, Manchester; and Rheumatic Diseases Centre, Hope Hospital, Salford, UK. Supported by a grant from the Arthritis Research Campaign (ARC). S.P Pushpakom, MPharm, PhD, Clinical Scientist, National Genetics Reference Laboratory, Department of Medical Genetics, St. Mary’s Hospital, Manchester; A.L. Herrick, MD, FRCP, Consultant Rheumatologist, Rheumatic Diseases Centre, Hope Hospital; S. Kumar, PhD, FRCPath, Professor, Department of Pathology; J. Worthington, PhD, Professor of Chronic Disease Genetics, ARC Epidemiology Unit, University of Manchester. Address reprint requests to Dr. S.P. Pushpakom, National Genetics Reference Laboratory, Department of Medical Genetics, St. Mary’s Hospital, Hathersage Road, Manchester M13 0JH, UK. E-mail: sudeep.parameshwar@cmmc.nhs.uk Accepted for publication September 7, 2007. Abnormalities of the microvasculature are an integral part of the systemic sclerosis (SSc) disease process and are well demonstrated by nailfold capillary microscopy: typical fea- tures include widening of capillary loops and areas of avascu- larity. These microvascular abnormalities lead to ischemic features such as Raynaud’s phenomenon, fingertip ulcers, and gangrene. Digital ischemia in turn results in hypoxia, which is expected to drive compensatory angiogenesis 1 ; however, this phenomenon does not happen in SSc 2 . Angiogenesis is a com- plex physiological process modulated by a number of factors, including the balance between pro- and anti-angiogenic fac- tors. A study by Distler, et al 3 did not find any difference in the levels of serum basic fibroblast growth factor (pro-angio- genic) and endostatin (anti-angiogenic) between patients with SSc and controls, but observed a significant increase in the levels of vascular endothelial growth factor (VEGF), a pro- angiogenic factor. This increase in VEGF is expected to stim- ulate subepidermal angiogenesis in SSc skin; however, VEGF-driven compensatory angiogenesis is not observed in SSc. The faint immunoreactivity observed with αvß3 integrin receptor, a mediator of VEGF-regulated angiogenesis, in SSc skin has been suggested by Konttinen, et al to be one of the reasons for failure of angiogenesis in SSc 2 . Recently the role of vascular basement membrane (VBM) in regulating angio- genesis has been highlighted by several investigators. VBM is located between the endothelial cell (EC) lining and pericytes that make up the outer vessel wall and regulates cell growth, cell differentiation, and cell-matrix interactions, as well as apoptosis. It is mainly composed of type IV, XV, and XVIII collagens, laminin, heparin-sulfate proteoglycans, fibulins, and osteonectin. These VBM components support the growth and survival of vascular EC, thereby critically regulating angiogenesis 4 . The exact role of each of these components in angiogenesis remains largely unknown; however, domains of collagen IV, collagen XV, and collagen XVIII are known to have anti-angiogenic functions 5 . The various collagen-derived www.jrheum.org Downloaded on May 18, 2022 from