Background/Purpose:

In patients with ankylosing spondylitis (AS), smoking is associated with increased disease activity and more radiographic damage. However, the mechanisms underlying the effects of smoking are still unknown. The aim of the study was to investigate the relationship between smoking and acute phase reactants, and serum levels of molecules involved in bone formation in patients with AS.

Methods:

This was an observational, cross-sectional study. Serum samples for total Dickkopf-1 (Dkk-1), sclerostin and vascular endothelial growth factor (VEGF) were obtained from TNF inhibitor naïve patients with AS according to the modified New York criteria. Patients with at least the last 3 months use of glucocorticoids, DMARDs or high dose NSAIDs (a mean NSAIDs intake index ≥50) were excluded. C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), BASDAI, BASFI and radiographic severity (assessed by mSASSS and BASRI-s) were assessed for each patient. Demographic variables and smoking history were obtained, and smoking pack-years were calculated.

Results:

Sixty-five patients were included in the study [mean age 41.3±1.5 years; duration of symptoms 13.4±1.2 years; male gender 61 patients (93.8%)]. Using Mann-Whitney U test, CRP (18.9±12.5 mg/l vs 12.4±9.3 mg/l, p=0.019) and VEGF levels (381.6±121.4 pg/ml vs 310.9±131.5 pg/ml, p=0.02) were higher in patients with current smoking compared with those without, while there was no difference for ESR and the levels of Dkk-1 and sclerostin. Ever smokers had higher VEGF levels (369.9±128.7 pg/ml vs 252.7±94.4 pg/ml, p=0.006) compared with never smokers, while there was no difference for ESR, CRP and the levels of Dkk-1 and sclerostin between the two groups. Among acute phase reactants and molecules involved in bone formation, only VEGF levels were correlated with smoking pack-years (r=0.389, p=0.001). In multiple linear regression analysis, which involved all demographic, clinical and radiographic variables that presented significant association with smoking pack-years in the bivariate correlations, VEGF levels were an independent variable of smoking pack-years (β=0.497, p<0.001).

Conclusion:

It seems that VEGF levels are positively associated with smoking in patients with AS. The effect of smoking on disease activity and/or radiographic spinal progression to be mediated by increased VEGF levels could be supposed.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-of-smoking-with-acute-phase-reactants-and-molecules-involved-in-bone-formation-in-patients-with-ankylosing-spondylitis/