TGFB1 and allergic asthma: Given that only approximately 2% of all asthmatic patients have uncontrolled persistent allergic asthma [63] and that 85% of asthma exacerbations are triggered by viral infections [64], it can be speculated that most asthmatic patients do not have upregulated TGF-β expression at the time of viral challenge and therefore are not protected against viral infections.