Mucus is a biological gel within the lung designed to behave like an “escalator” with the ability to capture potentially harmful inhaled materials (e.g. pathogens, particulates) and carry these materials via mucociliary clearance up to the throat to be swallowed and sterilized. MUC5B and MUC5AC are large, gel-forming mucins that assemble to form airway mucus gels. In individuals with chronic lung diseases such as asthma and bronchitis, biochemical analysis of mucus produced by cough revealed mucin composition is altered as a function of disease severity, with a shift from MUC5B to MUC5AC as the predominant secreted mucin. However due to the lack of appropriate models, it is not yet fully understood how an imbalance in ratio of MUC5B to MUC5AC contributes to the biological function of mucus. Recently, we have engineered a mucin-based biomaterial with native-like viscoelasticity, here termed ‘synthetic mucus’. To understand mucus dysfunction in asthma, we customized synthetic mucus to mimic the biochemical and biophysical properties of airway mucus in health and in asthma. In addition, we characterized the rheological properties and transport function of mucus in differentiated human airway tissue cultures genetically engineered to secrete either MUC5B or MUC5AC. These bioengineered models provide key insights on how MUC5B and MUC5AC work in concert to enable host mucosal barrier function providing a highly valuable means to understand their roles in health and disease.