Stereochemistry of leukotriene B4 metabolites formed by the reductase pathway in porcine polymorphonuclear leukocytes: inversion of stereochemistry of the 12-hydroxyl group

Abstract

Leukotriene B4 (LTB4), a potent proinflammatory agent, is a major metabolite of arachidonic acid in polymorphonuclear leukocytes (PMNL). When porcine PMNL were incubated with LTB4 and the products purified by reversed-phase high-pressure liquid chromatography (HPLC), we previously identified two metabolites: 10,11-dihydro-LTB4 and 10,11-dihydro-12-oxo-LTB4 [Powell, W. S., & Gravelle, F. (1989) J. Biol. Chem. 264, 5364-5369]. Further analysis of the reaction products by normal-phase HPLC has now revealed the presence of a third major metabolite of LTB4. This product is not formed in detectable amounts in the first 5 min of the reaction but accounts for about 20-30% of the reaction products after 60 min, when LTB4 has been completely metabolized. The mass spectrum and gas chromatographic properties of the new metabolite are identical with those of 10,11-dihydro-LTB4, suggesting that it is a stereoisomer of this compound. This product was identified as 10,11-dihydro-12-epi-LTB4 [i.e., 5(S),12(R)-dihydroxy-6,8,14-eicosatrienoic acid] by comparison of its chromatographic properties with those of the authentic chemically synthesized compound. Both 10,11-dihydro-LTB4 and 10,11-dihydro-12-oxo-LTB4 were enzymatically converted to 10,11-dihydro-12-epi-LTB4 by porcine PMNL, the former compound being the better substrate. The reaction was reversible, since both 10,11-dihydro-12-epi-LTB4 and 10,11-dihydro-12-oxo-LTB4 could be converted to 10,11-dihydro-LTB4.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism of 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid and other hydroxylated fatty acids by the reductase pathway in porcine polymorphonuclear leukocytes

“…We have previously reported that porcine PMNL convert LTB4 to 10,1 l-dihydro-LTB4,10,11-dihydro-12-epi-LTB4, and 10.11dihydro-12-oxo-LTB4 (Powell & Gravelle, 1989;Wainwright et al, 1990). 10,11-Dihydro-12-epi-LTB4 was not an initial product but was formed after a lag period, presumably from either 10,11-dihydro-LTB4 or 10,11-dihydro-12-oxo-LTB4 (Wainwright et al, 1990).…”

“…We have previously reported that porcine PMNL convert LTB4 to 10,1 l-dihydro-LTB4,10,11-dihydro-12-epi-LTB4, and 10.11dihydro-12-oxo-LTB4 (Powell & Gravelle, 1989;Wainwright et al, 1990). 10,11-Dihydro-12-epi-LTB4 was not an initial product but was formed after a lag period, presumably from either 10,11-dihydro-LTB4 or 10,11-dihydro-12-oxo-LTB4 (Wainwright et al, 1990). We have now shown that 12(5)-HETE is metabolized by porcine PMNL in a similar manner, giving 12(R)-hydroxy-5,8,14-eicosatrienoic acid, 12(5)-hydroxy-5,8,14-eicosatrienoic acid, and 12-oxo-5,8,l4-eicosatrienoic acid, which were identified by mass spectrometry and NMR spectroscopy.…”

“…However, the nature of the dihydro metabolite formed from LTB4 by porcine PMNL was different from that formed from the 6-trans isomers of LTB4 by human PMNL in that it was the 10,11-double bond of LTB4 which was reduced in the former (Powell & Gravelle, 1989). Porcine PMNL converted 10,1 l-dihydro-LTB4 to 10,11-dihydro-12-oxo-LTB4 (Powell & Gravelle, 1989) as well as to 10,11-dihydro-12-epi-LTB4 (Wainwright et al, 1990).…”

“…)-HETE, which is formed from arachidonic acid by a cytochrome P-450 (Capdevila et al, 1986), has greater chemotactic activity than 12(5)-HETE (Cunningham & 1986,1988). Although human PMNL did not appear to metabolize LTB4 by this pathway, this substance was metabolized to dihydro products by rat (Powell, 1987a) and porcine PMNL (Powell & Gravelle, 1989;Wainwright et al, 1990), rat mesangial cells and fibroblast tumor cells, mouse T-lymphocytes, and macrophages (Kaever et al, 1987), and human monocytes (Fauler et al, 1989) and alveolar macrophages (Schonfeld et al, 1988). However, the nature of the dihydro metabolite formed from LTB4 by porcine PMNL was different from that formed from the 6-trans isomers of LTB4 by human PMNL in that it was the 10,11-double bond of LTB4 which was reduced in the former (Powell & Gravelle, 1989).…”

Dehydrogenase reductase 9 (SDR9C4) and related homologs recognize a broad spectrum of lipid mediator oxylipins as substrates

“…In fact, one of the intriguing possibilities with respect to the physiological role of DHRS9 might be its participation in the so-called 12-hydroxyeicosanoid dehydrogenase/10,11-reductase pathway, which was implicated in metabolism of 12( S )-HETE, LTB 4 , and possibly of 13( S )-HODE ( 44 , 45 ). Pioneering studies carried out by Wainwright and Powell demonstrated that catabolic conversion of 12( S )-HETE and LTB 4 is initiated when both compounds are rapidly oxidized by 12-hydroxyeicosanoid dehydrogenase followed by reduction of the 10,11-double bond by 10,11-reductase ( 44 ).…”