Systemic Effects of Smoking

Smoking is one of the major lifestyle factors influencing the health of human beings. Life-long cigarette smokers have a higher prevalence of common diseases such as atherosclerosis and COPD with significant systemic impact. The present review evaluates current knowledge concerning possible pathways through which cigarette smoking can affect human health, with special focus on extrapulmonary effects. Long-term smoke exposure can result in systemic oxidants-antioxidants imbalance as reflected by increased products of lipid peroxidation and depleted levels of antioxidants like vitamins A and C in plasma of smokers. A low-grade systemic inflammatory response is evident in smokers as confirmed by numerous population-based studies: elevated levels of C-reactive protein (CRP), fibrinogen, and interleukin-6, as well as increased counts of WBC have been reported. Furthermore, rheologic, coagulation and endothelial function markers like hematocrit, blood and/or plasma viscosity, fibrin d-dimer, circulating adhesion molecules (intracellular adhesion molecule-1, selectins), tissue plasminogen activator antigen, and plasminogen activator inhibitor type I are altered in chronic cigarette smokers. Although most of smoking-induced changes are reversible after quitting, some inflammatory mediators like CRP are still significantly raised in ex-smokers up to 10 to 20 years after quitting, suggesting ongoing low-grade inflammatory response persisting in former smokers. New longitudinal epidemiologic and genetic studies are required to evaluate the role of smoking itself and possible gene/environment interplay in initiation and development of smoking-induced common diseases affecting humans.