Cigarette smoke modifies neutrophil chemotaxis, neutrophil extracellular trap formation and inflammatory response‐related gene expression

Background and Objective Cigarette smoking is a major risk factor for periodontitis, and smoking perturbs neutrophil reactive oxygen species production. This study tested the hypothesis that cigarette smoke extract ( CSE ) and its components/metabolites nicotine, cotinine and thiocyanate ( SCN ‐), may influence neutrophil functions. Material and Methods Chemotaxis was assessed in neutrophils pre‐treated with CSE using real‐time video microscopy. Neutrophil extracellular trap ( NET ) release in response to CSE , nicotine, cotinine, SCN ‐ as well as to phorbol 12‐myristate‐13‐acetate and hypochlorous acid following pre‐treatment with CSE , nicotine, cotinine or SCN ‐ was assessed using fluorescence‐based assays. The impact of CSE and SCN ‐ treatment on neutrophil respiratory burst‐ and inflammation‐related gene expression ( NFKBIE , DNAJB 1, CXCL 8, NCF 1, NCF 2, CYBB ) was determined by real‐time polymerase chain reaction. Results Both CSE and SCN ‐ pre‐treatment inhibited phorbol 12‐myristate‐13‐acetate‐stimulated NET release. Additionally, SCN ‐ inhibited hypochlorous acid‐stimulated NET formation, while SCN ‐ alone stimulated NET release. Overall, neutrophils pre‐treated with CSE exhibited reduced speed, velocity and directionality relative to untreated neutrophils. Although CSE and SCN ‐ promoted DNAJB 1 expression, increased redox‐related gene expression was only detected in response to SCN ‐. Conclusion These results suggest that CSE can alter ex vivo neutrophil activation by mechanisms independent of SCN ‐ and nicotine, and SCN ‐ may contribute to the perturbed innate immune responses observed in smokers.