title: Increased prevalence of low oligomeric state surfactant protein D with restricted lectin activity in bronchoalveolar lavage fluid from preterm infants.
abstract: BACKGROUND
  Surfactant protein D (SP-D) is a soluble oligomeric C-type lectin known to protect against lipopolysaccharide and ventilator-induced lung injury in preterm lambs. Here we assess the expression and functional status of SP-D in bronchoalveolar lavage fluid (BALF) from preterm infants at risk of chronic lung disease (CLD) of prematurity and term controls. This is the first systematic evaluation of SP-D function in any clinical cohort.
  
  
  METHODS
  SP-D was quantified in BALF from 28 ventilated preterm infants and five ventilated term infants. SP-D lectin activity was tested in a zymosan binding assay followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blot in BALF from the same infants. SP-D lectin activity was also tested towards maltose-agarose and mannan for selected BALF samples.
  
  
  RESULTS
  SP-D expression was lower on day 1 in those preterm infants who subsequently developed CLD but increased over the first 5 days of life in term and preterm neonates. The percentage of neonatal SP-D capable of binding zymosan rarely exceeded 50% in any BALF sample and was 3.5 times lower in preterm infants than term infants on day 1 of life. Similar binding defects were observed towards maltose-agarose and mannan. SDS-PAGE analysis revealed that zymosan-bound SP-D was more highly oligomerised (≥12-mers) than unbound SP-D, which was composed primarily of trimers and lower oligomeric forms.
  
  
  CONCLUSIONS
  Substantial and functionally relevant variation in the expression and oligomeric distribution of SP-D exists between preterm and term neonatal lung secretions. This has implications for proposed SP-D replacement therapy in this population.
authors: Department of Child Health, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff, UK.
authors: Sailesh
authors: S
authors: Kotecha
authors: Philip L
authors: PL
authors: Davies
authors: Howard W
authors: HW
authors: Clark
authors: Eamon P
authors: EP
authors: McGreal
mesh_terms: D015153:Blotting, Western; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008168:Lung / Q000378:metabolism*; D008297:Male; D037663:Pulmonary Surfactant-Associated Protein D / Q000096:biosynthesis*; D012121:Respiration, Artificial; D012127:Respiratory Distress Syndrome, Newborn / Q000378:metabolism* / Q000628:therapy
chemical_list: D037663:Pulmonary Surfactant-Associated Protein D