Inflammatory related changes in bone mineral content in adults with cystic fibrosis.
BACKGROUND
Proinflammatory cytokines stimulate osteoclast activity and this could lead to increased bone resorption in patients with cystic fibrosis. The aim of this study was to determine whether markers of systemic inflammation are related to changes in bone mineral content (BMC) in adults with cystic fibrosis.


METHODS
Total body BMC was assessed by dual energy x ray absorptiometry in 100 patients (54 male) of mean (SD) age 25.6 (7.1) years and forced expiratory volume in 1 second (FEV(1)) 61.8 (24.1)% predicted on recruitment to the study and 1 year later. Blood was also taken at these time points to measure markers of systemic inflammation.


RESULTS
After 1 year BMC had reduced by 16.1 (62.1) g, p = 0.01; (0.6 (2.8)%). The change in BMC was related to mean levels of interleukin (IL)-6 (r(s) = -0.39, p<0.001) and C reactive protein (r(s) = -0.34, p = 0.002), intravenous antibiotic use (r(s) = -0.27, p = 0.006) and oral corticosteroid use (r(s) = -0.20, p = 0.045). Urinary markers of osteoclast activity were also related to IL-6 (r(s) = 0.27, p = 0.02). Multiple linear regression revealed that IL-6 (coefficient -2.2 (95% CI -3.4 to -1.0) per pg/ml, p = 0.001), colonisation with Burkholderia cepacia (coefficient -46.8 (95% CI -75.5 to -18.1), p = 0.002), and annual change in BMI (coefficient 15.4 (95% CI 3.6 to 27.2) per kg/m(2), p = 0.011) were independently significant predictors of annual change in BMC.


CONCLUSIONS
These data suggest a pathophysiological mechanism by which chronic pulmonary infection results in bone loss in patients with cystic fibrosis.
Haworth
C S
CS
Department of Medicine, University of Manchester, Manchester Royal Infirmary, Manchester M13 9WL, UK.
Selby
P L
PL
Webb
A K
AK
Martin
L
L
Elborn
J S
JS
Sharples
L D
LD
Adams
J E
JE
D015502:Absorptiometry, Photon; D000328:Adult; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D015519:Bone Density; D003432:Cross-Linking Reagents / Q000032:analysis; D003550:Cystic Fibrosis / Q000097:blood* / Q000473:pathology / Q000503:physiopathology; D016207:Cytokines / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000473:pathology / Q000652:urine; D008297:Male; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000097:blood* / Q000473:pathology / Q000503:physiopathology
D015415:Biomarkers; D003432:Cross-Linking Reagents; D016207:Cytokines