Effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats

Objective: To evaluate the effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats. Methodology: In total, 32 male Wistar rats were divided into four groups (n = 8): AP—induced apical periodontitis; S—cigarette smoke inhalation; APS—induced AP and cigarette smoke inhalation; and C (control)—neither AP nor cigarette smoke inhalation. To induce cigarette smoke inhalation, the animals were kept in a chamber filled with tobacco smoke for 8 min thrice a day for 50 days. AP was induced 20 days after inhalation initiation by exposing their coronary pulp to their oral environment for 30 days. After animals were euthanized, their right hemimaxillae were removed for histopathological, semi-quantitative and immunohistochemical (F4/80, CD206 and iNOS) analyses. Results: Quantitative data showed a moderate number of inflammatory infiltrates in AP and an intense number in APS (p <.05). Comparing F4/80+ cells showed no statistically significant differences among groups, but we found more CD206+ cells in AP than in C and S (p >.05). INOS+ immunostaining showed a significant increase in AP and APS, when compared with C and S (p <.05). APS had more iNOS+ cells than AP (p <.05). Conclusion: Cigarette smoke inhalation worsened AP, leading to a predominantly pro- inflammatory profile in our experimental model.