Lipoxin B₄regulates human monocyte/neutrophil adherence and motility: design of stable lipoxin B₄analogs with increased biologic activity

Abstract

Lipoxins are biologically active products of arachidonic acid that are formed via cell-cell interactions, particularly those involving leukocytes. Lipoxin A4 and lipoxin B4 (LXB4), within similar concentration ranges, each inhibit human neutrophil, activate monocyte adherence and motility, and are rapidly converted by initial dehydrogenation to other inactive metabolites by human monocytes. Here, we exposed LXB4 to isolated recombinant 15-hydroxy-prostaglandin dehydrogenase (15-PGDH) and found that it was a good substrate for the enzyme (Km=6.9 microM); we identified the major product as 5-oxo-LXB4 via physical methods including liquid chromatography/tandem mass spectrometry. This is the first evidence of 15-PGDH converting a substrate hydroxyl group at a position other than the omega-6 carbon. Based on these observations, several LXB4 analogs were designed and prepared by total organic synthesis to test as stable mimetics: 5(S)-methyl-LXB4-me, 5(R)-methyl-LXB4-me, and 15-epi-LXB4-me (the aspirin-triggered form of LXB4). Both 5(S)-methyl-LXB4-me and 5(R)-methyl-LXB4-me were resistant to rapid conversion. In addition, actions of the stable analogs were evaluated separately with human mono-cytic cells and neutrophils, and 5(S)-methyl-LXB4-me was more potent (nM range) than LXB4 for both cell types. In contrast, 5(R)-methyl-LXB4-me was potent in inhibiting neutrophil transmigration across endothelial monolayers, but did not stimulate monocyte adherence. These results indicate that LXB4 analogs can be designed to resist rapid transformation and retain bioactivity with both monocytes and neutrophils. Moreover, they suggest that LXB4 stable analogs are useful tools to selectively evaluate the modes of actions of LXB4 with different tissues.

Lipoxins, Aspirin-Triggered Epi-Lipoxins, Lipoxin Stable Analogues, and the Resolution of Inflammation

“…Furthermore, the aspirin-triggered 15-epi-LXB 4 and the stable LX analogue 15(R/S)-methyl-LXA 4 (19) also stimulated phagocytosis. The enhanced efficacy and stability of LX analogues in modulation of leukocyte trafficking in models of inflammation and second organ injury after local and systemic administration has led to the proposal that these compounds might have therapeutic potential (17)(18)(19)(20). Consistent with this are our data that highlight the attractiveness of LX stable analogues, which are resistant to metabolic inactivation by monocytes/macrophages yet retain the activity of the native LX (17,19,21).…”

“…The rapid metabolic degradation of native LX by dehydrogenation at C15 and possibly -oxidation at C20 has prompted the design and synthesis of stable analogues, which retain many of the properties of the native LX, including inhibition of PMN adhesion and transmigration (17,4). In a cytokine primed milieu, the catalytic activity of aspirin-acetylated cyclooxygenase type 2 (COX-2) is shifted from a cyclooxygenase to 15R lipoxygenase.…”

A prospective, randomized trial for the prevention of mucositis in patients undergoing hematopoietic stem cell transplantation

“…Changes in intracellular Ca 2+ by release of cytosolic Ca 2+ and influx of extra cellular Ca 2+ effect leukocyte chemotaxis, modulation of adhesion molecules and elaboration of arachiodonic metabolites including prostaglandins, leucotrines and lipoxins. [38][39][40][41] These latter agents influence the inflammatory process and leukocyte adhesion. Prostaglandins are also involved in the pathogenesis of pain and fever in inflammation.…”

Mechanisms in anti-inflammation and resolution: the role of lipoxins and aspirin-triggered lipoxins

“…Moreover, reduction of the 15-oxo group by 15-PGDH yields 13,14-dihydro-LXA 4 , revealing an additional catalytic activity for this enzyme (11). LXB 4 can also be dehydrogenated by 15-PGDH at carbon 5 to produce 5-oxo-LXB 4 , therefore sharing a common route of inactivation (12). It has recently been shown that 15-oxo-LXA 4 is also produced from LXA 4 in mouse whole blood (13), suggesting that the mouse shares with humans a common pathway for LXA 4 inactivation.…”