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. Author manuscript; available in PMC: 2015 Jan 15.
Published in final edited form as: Annu Rev Physiol. 2013 Dec 2;76:467–492. doi: 10.1146/annurev-physiol-021113-170408

Figure 4. Transcellular biosynthesis of SPM occurs via airway neutrophil-epithelium interactions.

Figure 4

Transcellular biosynthesis of SPM provides a collaborative opportunity for two cell types to generate mediators together that neither cell type alone can efficiently produce. For example, arachidonic acid (AA) can be released from cell membranes for conversion by 15-LOX to 15S-HETE that is transferred to neutrophils for subsequent transformation by 5-LOX to an unstable epoxytetraene intermediate that hydrolases can convert to LXA4 and LXB4. Depicted as unidirectional, lipoxin biosynthesis can proceed bidirectionally with neutrophil 5-LOX conversion of AA to leukotriene A4 followed by release and transformation to lipoxins by epithelial 15-LOX. Protectin D1 does not require cell-cell interactions for its generation by 15-LOX catalyzed conversion of DHA via an epoxide-containing intermediate.