Decoding oral impact: tobacco and nicotine effects on the microbiome-immune-metabolome axis

Cigarette smoking is an important risk factor for periodontal disease (“gum disease”). The components of cigarette smoke change the bacteria in the mouth and impact the immune system, making it more likely for the disease to manifest. E-cigarettes have become a popular alternative to cigarettes and are often marketed as a safer alternative. However, it has been shown that these devices also lead to changes in the oral environment that can lead to disease. While studies have detailed what happens below the gumline as a result of these habits, few have explored the changes that occur in saliva and along the surfaces of the cheeks and gums. The goal of our project was to acquire a global picture of the changes that occur in the mouth as a result of these habits before any disease occurrence. This could help identify indicators of future disease onset and progression.

Saliva, cheek swabs, and cheek tissue from 31 subjects, some of whom were smokers and e-cigarette users, were collected and analyzed. In saliva, the levels of different types of bacteria were assessed, as well as the levels of metabolites (small molecules) and components of the immune system. In the cheek tissue, molecules important for inflammation and immunity were measured. Several laboratory tests were performed to observe the communication between the bacteria, immune system, and metabolites.

Different types of bacteria were present in the three groups. Likewise, the saliva contained different amounts of specific metabolites and immune system components. The tissue of smokers and ENDS users showed that specific genes important for inflammation and the immune system were either increased or decreased. When combining all the data, subjects who used nicotine had more inflammation in their saliva and mouth tissues.