title: Fibrin clot structure is affected by levels of particulate air pollution exposure in patients with venous thrombosis.
abstract: Particulate air pollution is a risk factor for cardiovascular diseases and thrombosis. Long-term exposure to particulate matter with a diameter<10μm (PM10) has been associated with an increased risk of venous thrombosis.
  
  
  
  The aim of this study was to investigate whether or not particulate air pollution alters fibrin clot structure and thus modulates thrombosis risk.
  
  
  
  We investigated fibrin polymerization by turbidity (maximum absorbance mOD), clot structure by confocal microscopy (fibre number per μm) and fibrin pore size by permeability (Ks×10(-10)cm(2)) in 103 patients with deep vein thrombosis and 121 healthy controls, for whom levels of air pollution exposure had been recorded. Exposure groups were defined by mean PM10 concentrations over the 730days before the event.
  
  
  
  We found a higher average number of fibres per clot area in patients than controls, but no difference in Ks or fibre thickness. When the two groups were divided into high or low exposure to PM10, a significantly denser fibrin clot network structure with thicker fibres (higher maximum absorbance, p<0.05), decreased permeability (lower Ks value, p<0.05) and higher average fibre numbers per clot area (p<0.05) was observed in patients in the high exposure group compared to those with low exposure. There were no significant differences in fibrin clot structure between the two exposure levels in healthy subjects.
  
  
  
  PM10 levels are associated with altered fibrin clot structure in patients with deep vein thrombosis but not in controls, suggesting that air pollution may trigger differences in fibrin clot structure only in patients predisposed to thrombotic disease.
authors.affiliation: Environmental Epidemiology, Leeds Institute for Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds, UK; Thrombosis Research Group, Leeds Institute for Cardiovascular and Metabolic Medicine, Multidisciplinary Cardiovascular Research Centre School of Medicine, University of Leeds, Leeds, UK.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Pan
authors.affiliation: Institute for Global Food Security, Queens's University Belfast, Belfast, UK.
authors.forename: Yun Yun
authors.initials: YY
authors.lastname: Gong
authors.affiliation: A. Bianchi Bonomi Haemophilia and Thrombosis Centre, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Ida
authors.initials: I
authors.lastname: Martinelli
authors.affiliation: EPIGET LAB, University of Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Angelici
authors.affiliation: EPIGET LAB, University of Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Favero
authors.affiliation: Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.
authors.forename: Pier Alberto
authors.initials: PA
authors.lastname: Bertazzi
authors.affiliation: Scientific Direction, IRCCS Ca' Granda Foundation Maggiore Hospital, Milan, Italy.
authors.forename: Pier M
authors.initials: PM
authors.lastname: Mannucci
authors.affiliation: Thrombosis Research Group, Leeds Institute for Cardiovascular and Metabolic Medicine, Multidisciplinary Cardiovascular Research Centre School of Medicine, University of Leeds, Leeds, UK. Electronic address: r.a.s.ariens@leeds.ac.uk.
authors.forename: Robert A S
authors.initials: RA
authors.lastname: Ariëns
authors.affiliation: Environmental Epidemiology, Leeds Institute for Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds, UK.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Routledge
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry / Q000633:toxicity; D016022:Case-Control Studies; D005260:Female; D005337:Fibrin / Q000648:ultrastructure*; D006801:Humans; D007558:Italy; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry / Q000633:toxicity; D012307:Risk Factors; D020246:Venous Thrombosis / Q000097:blood / Q000209:etiology*
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D005337:Fibrin
keywords: Air pollution; Blood clotting; Fibrin; Particulate matter; Pulmonary embolism; Venous thrombosis