MUC5AC and infection: Boron (B) is an essential element for human host microbiota, and a deficiency of boron can lead to dysbiosis due to a deficiency of the autoinducer-2–furanosyl borate diester (AI-2B) signalling molecule and the degradation of the mucus gel layer in the mucin gel structure, due to a B concentration deficiency in the mucin gel composition, and thereby infections caused by the direct interactions of the bacterial biofilm with the host cell due to an impaired mucus gel layer [31,62,63,64].