Previous studies on sputum microbiome in asthma and COPD9,32 or in severe asthma8,10,33 showed an association between neutrophil-high phenotype and γ-proteobacteria or Haemophilus, and studies during exacerbations27 and at stable state9 identified a cluster mainly containing patients with COPD and some with asthma, which was characterized by an increased ratio of γ proteobacteria to Firmicutes and high IL1-β and TNF-α levels. Here, TNF is linked to chronic obstructive pulmonary disease.