Fig. 2.

Environmental factors associated with asthma and their influence on the gut-lung axis. Environmental factors can have a positive/protective effect (green circles) or a negative/enhancing effect (red circles) on asthma development. For some of these factors (e.g., antibiotics, pollution), it was demonstrated that they are able to interfere with the gut and/or lung microbiome, leading to dysbiosis and disturbances in the bidirectional exchange via the gut-lung axis, thereby enhancing asthma prevalence. Protective factors such as farming environment or intake of probiotics account for lower asthma incidences, but the direct impact on the gut or lung microbiome still needs to be analyzed in more detail