TNF and asthma: TNFα expression is upregulated in asthmatic lungs, particularly in patients with severe refractory asthma or neutrophilic asthma (Ying et al., 1991; Bradding et al., 1994; Howarth et al., 2005; Berry et al., 2006; Brightling et al., 2008; Baines et al., 2011; Kuo et al., 2017).