TLR4 and asthma: In addition, studies have shown the increased expressions of TLR2, TLR3, and TLR4 in patients with severe asthma as well as associated morbidity, suggesting their potential role in the development of severe or even fatal asthmatic exacerbations (Lipinski et al., 2021[12]; Ferreira et al., 2012[5]; Hansbro et al., 2017[8]).