Compared with MAP infection alone, nicotine upregulated MyD88 and IL-8 expression, the latter showed more noticeable change of 2.5-fold (Figure 2A,B) (MAP + nicotine: 22.3 ± 2.09 vs. MAP alone: 13.39 ± 1.80; p < 0.05, for MyD88), (MAP + nicotine: 6.40 ± 0.52 vs. MAP alone: 3.52 ± 0.62; p < 0.05, for IL-8). Here, MYD88 is linked to infection.