Serum IP-10 as a biomarker of human rhinovirus infection at exacerbation of COPD.
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.
Quint
Jennifer K
JK
Academic Unit of Respiratory Medicine, University College London, Rowland Hill St, London NW3 2PF, England. j.a.wedzicha@medsch.ucl.ac.uk.
Donaldson
Gavin C
GC
Goldring
James J P
JJ
Baghai-Ravary
Ramin
R
Hurst
John R
JR
Wedzicha
Jadwiga A
JA
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
D015415:Biomarkers; C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D015850:Interleukin-6; D002097:C-Reactive Protein