Lipoxin A4 Analog Research Articles

Lipoxin A4 and aspirin-triggered 15-epi-LXA4 inhibit tumor necrosis factor-alpha-initiated neutrophil responses and trafficking: novel regulators of a cytokine-chemokine axis relevant to periodontal diseases.

The impact of lipoxin A4 (LXA4) and aspirin-triggered-lipoxins (ATL) was investigated in tumor necrosis factor (TNF alpha)-initiated neutrophil (PMN) responses in vitro and in vivo using LX analogs that are metabolically more stable. At nanomolar levels, the LXA4 and ATL analog 15 R/S-methyl-LXA4 each blocked TNF alpha-stimulated IL-1 beta release by isolated human PMN in vitro. These LXA4-ATL actions were time- and concentration-dependent. The TNF alpha-induced IL-1 beta gene expression was also regulated by 15 R/S-methyl-LXA4. In addition, 15 R/S-methyl-LXA4 added to murine air pouches dramatically inhibited TNF alpha-stimulated leukocyte trafficking in vivo, as well as altered the appearance of both macrophage inflammatory peptide-2 and IL-1 beta and concomitantly stimulated IL-4 in pouch exudates. These findings from in vitro and in vivo experiments indicate that both LXA4 and ATL are regulators of TNF alpha-directed neutrophil actions and stimulate IL-4 in exudates and thus regulate mediators that are held to play an important role in the pathogenesis of periodontal disease.

Lipoxin (LX)A4 and aspirin-triggered 15-epi-LXA4 inhibit tumor necrosis factor 1alpha-initiated neutrophil responses and trafficking: regulators of a cytokine-chemokine axis.

The impact of lipoxin A4 (LXA4) and aspirin-triggered lipoxins (ATLs) was investigated in tumor necrosis factor (TNF)-alpha-initiated neutrophil (polymorphonuclear leukocyte) responses in vitro and in vivo using metabolically stable LX analogues. At concentrations as low as 1-10 nM, the LXA4 and ATL analogues each inhibited TNF-alpha-stimulated superoxide anion generation and IL-1beta release by human polymorphonuclear leukocytes. These LXA4-ATL actions were time and concentration dependent and proved selective for TNF-alpha, as these responses were not altered with either GM-CSF- or zymosan-stimulated cells. TNF-alpha-induced IL-1beta gene expression was also regulated by both anti-LXA4 receptor antibodies and LXA4-ATL analogues. In murine air pouches, 15R/S-methyl-LXA4 dramatically inhibited TNF-alpha-stimulated leukocyte trafficking, as well as the appearance of both macrophage inflammatory peptide 2 and IL-1beta, while concomitantly stimulating IL-4 in pouch exudates. Together, these results indicate that both LXA4 and ATL regulate TNF-alpha-directed neutrophil actions in vitro and in vivo and stimulate IL-4 in exudates, playing a pivotal role in immune responses.

Pathogen-induced chemokine secretion from model intestinal epithelium is inhibited by lipoxin A4 analogs.

Enteric pathogens induce intestinal epithelium to secrete chemokines that direct movement of polymorphonuclear leukocytes. Mechanisms that might downregulate secretion of these proinflammatory chemokines and thus contain intestinal inflammation have not yet been elucidated. The antiinflammatory activities exhibited by the arachidonate metabolite lipoxin A4 (LXA4) suggests that this eicosanoid, which is biosynthesized in vivo at sites of inflammation, might play such a role. We investigated whether chemokine secretion could be regulated by stable analogs of LXA4. Monolayers of T84 intestinal epithelial cells were infected with Salmonella typhimurium, which elicits secretion of distinct apical (pathogen-elicited epithelial chemoattractant) and basolateral (IL-8) chemokines. Stable analogs of LXA4 inhibited S. typhimurium-induced (but not phorbol ester-induced) secretion of both IL-8 and pathogen-elicited epithelial chemoattractant. LXA4 stable analogs did not alter bacterial adherence to nor internalization by epithelia, indicating that LXA4 stable analogs did not block all signals that Salmonella typhimurium activates in intestinal epithelia, but likely led to attenuation of signals that mediate chemokine secretion. Inhibition of S. typhimurium-induced IL-8 secretion by LXA4 analogs was concentration- (IC50 approximately 1 nM) and time-dependent (maximal inhibition approximately 1 h). As a result of these effects, LXA4 stable analogs inhibited the ability of bacteria-infected epithelia to direct polymorphonuclear leukocyte movement. These data suggest that LXA4 and its stable analogs may be useful in downregulating active inflammation at mucosal surfaces.

Release of pro-inflammatory chemokines from model intestinal epithelia is inhibited by lipoxin A4 analogs

Release of pro-inflammatory chemokines from model intestinal epithelia is inhibited by lipoxin A4 analogs

Lipoxin A4 stable analogs inhibit leukocyte rolling and adherence in the rat mesenteric microvasculature: role of P-selectin.

Three different stable lipoxin A4 (LXA4) analogs (i.e., 16-phenoxy-LXA4-Me, 15-cyclohexyl-LXA4-Me, and 15-R/S-methyl-LXA4-Me) were studied for their ability to modulate leukocyte-endothelial cell interactions in the rat mesenteric microvasculature. Superfusion of the rat mesentery with 50 micromol/liter NG-nitro-L-arginine methyl ester (L-NAME) caused a significant, time-dependent increase in leukocyte rolling (56 +/- 8 cells/min; P < 0.01 vs. control) and leukocyte adherence (12.5 +/- 1. 2 cells/100 micron length of venule; P < 0.01 vs. control) after 120 min of superfusion. Concomitant superfusion of the rat mesentery with 10 nmol/liter of each of three lipoxin analogs consistently and markedly attenuated L-NAME-induced leukocyte rolling to 10 +/- 4 (P < 0.01), 4 +/- 1 (P < 0.01), and 32 +/- 7 (P < 0.05) cells/min, and adherence to 4 +/- 0.8 (P < 0.01), 1.1 +/- 0.4 (P < 0.01), and 7 +/- 0.7 (P < 0.05) cells/100 micron length of venule (16-phenoxy-LXA4-Me, 15-cyclohexyl-LXA4-Me, and 15-R/S- methyl-LXA4-Me, respectively). No alterations of systemic blood pressure or mesenteric venular shear rates were observed in any group. Immunohistochemical up-regulation of P-selectin expression on intestinal venular endothelium was significantly increased (P < 0.01) after exposure to L-NAME, and this was significantly attenuated by these lipoxin analogs (P < 0.01). Thus, in vivo superfusion of the rat mesentery with stable lipoxin analogs at 10 nmol/liter reduces L-NAME-induced leukocyte rolling and adherence in the mesenteric rat microvasculature by attenuating P-selectin expression. This anti-inflammatory mechanism may represent a novel and potent regulatory action of lipoxins on the immune system.