title: Serum IP-10 as a biomarker of human rhinovirus infection at exacerbation of COPD.
abstract: BACKGROUND
  Human rhinovirus (HRV) is the most frequent virus associated with COPD exacerbations. Viral infections increase exacerbation severity and likelihood of hospitalization. As ease of sampling blood makes serum a more practical marker than sputum, we investigated whether changes in serum interferon-gamma-inducible protein 10 (IP-10) from baseline to exacerbation were higher in airway HRV-positive exacerbations and whether IP-10 levels related to HRV load.
  
  
  METHODS
  One hundred thirty-six patients with COPD and 70 controls were included over 2 years and 72 exacerbations sampled. HRV positivity and load were determined by reverse transcriptase-polymerase chain reaction in nasopharyngeal swabs and/or sputum at baseline and exacerbation. IP-10 was measured by enzyme-linked immunosorbent assay in serum and compared with HRV load.
  
  
  RESULTS
  At baseline, serum IP-10 was higher in patients with COPD than controls; medians were 149.4 pg/mL (103-215) and 111.7 pg/mL (82-178), P = .02. The presence of HRV at baseline did not increase IP-10: patients with COPD, 166.9 pg/mL (110-240) and 149.4 pg/mL (103-215), P = .30; controls, 136.4 pg/mL (77-204) and 111.7 pg/mL (82-178), P = .53. IP-10 increased significantly from baseline to exacerbation in HRV-positive exacerbations: 154.9 pg/mL (114.0-195.1) to 207.5 pg/mL (142.1-333.5), P = .009. There was no change in IP-10 between baseline and exacerbation in HRV-negative exacerbations: 168.3 pg/mL (94.3-249.8) and 175.6 pg/mL (107.2-290.4), P = .49. At exacerbation, IP-10 correlated with sputum viral load: rho = 0.48; P = .02. In receiver operating characteristics analysis, the combination of IP-10 and coryzal symptoms gave an area under the curve of 0.82 (95% CI, 0.74-0.90).
  
  
  CONCLUSIONS
  IP-10 increases from baseline to exacerbation in HRV-positive exacerbations and correlates with sputum HRV load. Serum IP-10 may be useful as a novel marker for these events.
authors.affiliation: Academic Unit of Respiratory Medicine, University College London, Rowland Hill St, London NW3 2PF, England. j.a.wedzicha@medsch.ucl.ac.uk.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Quint
authors.forename: Gavin C
authors.initials: GC
authors.lastname: Donaldson
authors.forename: James J P
authors.initials: JJ
authors.lastname: Goldring
authors.forename: Ramin
authors.initials: R
authors.lastname: Baghai-Ravary
authors.forename: John R
authors.initials: JR
authors.lastname: Hurst
authors.forename: Jadwiga A
authors.initials: JA
authors.lastname: Wedzicha
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D054357:Chemokine CXCL10 / Q000097:blood*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000821:virology; D010850:Picornaviridae Infections / Q000097:blood* / Q000175:diagnosis* / Q000503:physiopathology; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000503:physiopathology / Q000821:virology*; D012189:Retrospective Studies; D012229:Rhinovirus / Q000302:isolation & purification; D013183:Sputum / Q000821:virology; D019562:Viral Load; D014797:Vital Capacity / Q000502:physiology
chemical_list: D015415:Biomarkers; C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D015850:Interleukin-6; D002097:C-Reactive Protein