Acute lung injury: how the lung inflammatory response works.

The purpose of this article is to provide an overview of the lung inflammatory response in rodents. Topics to be discussed will be initiation of the inflammatory response 1, inflammatory products that are responsible for tissue damage, and the intrinsic pathways that regulate (depress) the inflammatory response leading to its containment 2. Acute lung injury in rodents (mice, rats) can be induced by intrapulmonary deposition of immunoglobulin (Ig)G immune complexes, which trigger an intense inflammatory response characterised by the influx of polymorphonuclear neutrophils (PMN), interstitial and alveolar oedema, and intra­alveolar haemorrhage 3. This model of acute inflammation has been extensively evaluated in order to understand how the acute inflammatory response is triggered. This inflammatory response is dependent on generation of the powerful complement activation product C5a. Generation of C5a in lung can be accomplished by activation of any one of the three pathways of complement activation (classical, alternative and lectin pathways). An altogether different pathway for C5a generation in lung involves cleavage of C5, which is produced by lung cells, …