Toxicological effects of cigarette smoke on Ana-1 macrophages in vitro

Cigarette smoke exposure is associated with increased risk of different disorders. Immunological dysfunction especially in macrophages is one of important reasons in the initiation, progression and exacerbation of smoke-related pulmonary illnesses. However, it is still obscure how cigarette smoke impacts the vitality and functions of macrophages. In the present study, we examined the effects of cigarette smoke extract (CSE) on mouse Ana-1 macrophages and tried to elucidate the involved mechanism. The results showed CSE induced cell apoptosis accompanied by increased releasing of lactate dehydrogenase (LDH), mitochondrial injury and oxidative stress. It also inhibited anti-apoptosis protein Bcl-2 expression and promoted pro-apoptosis protein Bax and Bad expressions. Moreover, low-dose CSE increased nuclear NF-κB levels of macrophages; on the contrary, high-dose CSE or long-time treatment decreased it. These observations were in correspondence with changes of intracellular ROS level and antioxidant enzymes' activity. Furthermore, pretreatment with 10 μM of NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) for 1 h significantly enhanced macrophage apoptosis. Taken together, these data implied that mitochondrial dysfunction and oxidative stress played important roles in the injury of Ana-1 cells caused by CSE, which was related to NF-κB pathway; an anti-apoptotic program played a dominant role at low doses/short-term exposure to CSE, whereas a pro-apoptotic program was initiated at high doses/long-term exposure.