Hepoxilin

Hepoxilins (HxA3 and HxB3) are nonclassic eicosanoid hormones involved in inflammation.

History
Hepoxilins were identified and named in Canada in 1984 by CR Pace-Asciak and JM Martin.

Biochemistry
They derive from arachidonic acid via oxidation by the enzyme 12-lipoxygenase. Hepoxilins are differentiated from closely related eicosanoids, the leukotrienes and the lipoxins, in that hepoxilins have no conjugated double bonds. Corresponding trioxlins A4 and B4 are formed by the same pathway from EPA

Physiological effect
In the skin, Hx are pro-inflammatory, but in neutrophils they are anti-inflammatory. Hx are potent insulin secretagogues. One hepoxilin, HepA3, mediates neutrophil migration across the intestines. Hepoxilins are also produced in the brain. Cells under oxidative stress secrete HX3, which in turn upregulates peroxidase, decreasing oxidative stress. This is proposed to constitute a compensatory defense response to protect the vitality and functionality of the cell.