ICAM1 and chronic obstructive pulmonary disease: Furthermore, oxidative stress is believed to upregulate expression of intercellular adhesion molecule-1 (ICAM-1), and platelet activating factor receptors (PAFR) allowing attachment and invasion of respiratory bacteria, including S. pneumoniae, Haemophilus influenzae and Pseudomonas aeruginosa, which are also important bacterial pathogens in COPD [105–107].