α1-Antitrypsin low-density-lipoprotein serves as a marker of smoking-specific oxidative stress

While smoking cessation (SC) leads to a reduction of cardiovascular events, atherogenic biomarkers specifically connected with cigarette smoking and SC are unknown. Circulating levels of oxidatively modified low-density-lipoprotein (LDL) are associated with a high risk of cardiovascular diseases. Recently, two novel, oxidatively modified LDL markers, serum amyloid A-LDL (SAA-LDL) and α1-antitrypsin-LDL (AT-LDL), were identified; however, the significance of SAA-LDL and AT-LDL as cardiovascular risk markers is unknown.

We carried out a cross-sectional study involving 243 patients, and determined serum levels of SAA-LDL and AT-LDL.

Both serum levels of SAA-LDL and AT-LDL were significantly increased in current compared to non-current smokers. Stepwise regression analysis revealed that the current smoking status and duration of smoking were strong independent determinants of the AT-LDL level. In contrast, high-sensitivity C-reactive protein was the strongest determinant of the SAA-LDL level. In multiple logistic regression analysis, the current smoking status was most closely associated with the AT-LDL level. Successful SC employing a 12-week program significantly increased the body mass index and serum levels of obesity-related markers. Notably, successful SC significantly decreased levels of AT-LDL, but not those of SAA-LDL.

The present study provides the first evidence for the distinct characteristics of two novel, oxidatively modified LDL markers, SAA-LDL and AT-LDL. In contrast to SAA-LDL, an inflammatory marker, AT-LDL serves as a marker of smoking-specific oxidative stress. These findings warrant further investigations to clarify if AT-LDL provides a key link between smoking and cardiovascular diseases.