TLR9 and chronic obstructive pulmonary disease: A role for TLR9 activation in non-allergic neutrophilic airway inflammation and airway disease including COPD has been proposed previously (Greene et al., 2005; Mortaz et al., 2009; Mortaz et al., 2010; Knuefermann et al., 2007; Schwartz et al., 1997; Tasaka et al., 2009; Faust et al., 2020).