Plasma suPAR is lowered by smoking cessation: a randomized controlled study

Background: Soluble urokinase plasminogen activator receptor (suPAR) is a stable inflammatory biomarker. In patients, suPAR is a marker of disease presence, severity and prognosis. In the general population, suPAR is predictive of disease development, such as diabetes and cardiovascular disease and, in smokers, predictive of long-term lung cancer development. Whether smoking cessation impacts the suPAR level is unknown.

Materials and methods: Forty-eight smokers were randomized into three groups of 16: (i) continued to smoke 20 cigarettes per day, (ii) refrained from smoking and used transdermal nicotine patches and (iii) refrained from smoking and used placebo patches. Nonsmokers were included for comparison. suPAR and C-reactive protein (CRP) levels were measured by ELISA.

Results: At baseline, the suPAR level was significantly higher in the 48 smokers (median 3·2 ng mL, IQR (2·5-3·9)) than in 46 never smokers (1·9 ng/mL (1·7-2·2)). In smokers randomized to smoking cessation, suPAR levels after 4 weeks of stopping were decreased and no longer significantly different from the never smokers values. SuPAR decreased in both those who received a placebo as well as nicotine patch. Interestingly, those with the highest suPAR level at time of smoking were also those with the highest level of suPAR after smoking cessation. In contrast, smoking or smoking cessation had no influence on CRP levels.

Conclusion: Our study suggests that the suPAR level may aid to personalize the risk of smoking by identifying those smokers with the highest risk of developing disease and who may have the most benefit of smoking cessation.