TGFB1 and asthma: Furthermore, in addition to endogenously produced epithelial-derived TGF-β2, other sources of TGF-β isoforms such as eosinophils whose numbers are increased in asthmatic bronchial epithelium during RV colds and persist during convalescence [21] may also contribute to suppression of the innate immune response to RV infection in asthma.