Lipoxin A4 Reduces Inflammation Through Formyl Peptide Receptor 2/p38 MAPK Signaling Pathway in Subarachnoid Hemorrhage Rats.

Lipoxin A4 (LXA4) has been reported to reduce inflammation in several neurological injury models. We studied the effects of LXA4 on neuroinflammation after subarachnoid hemorrhage (SAH) in a rat model. Two hundred and thirty-eight Sprague-Dawley male rats, weight 280-320 g, were used. Exogenous LXA4 (0.3 and 1.0 nmol) were injected intracerebroventricularly at 1.5 hours after SAH. Neurological scores, brain water content, and blood-brain barrier were evaluated at 24 hours after SAH; Morris water maze and T-maze tests were examined at 21 days after SAH. The expression of endogenous LXA4 and its receptor formyl peptide receptor 2 (FPR2), as well as p38, interleukin-1β, and interleukin-6 were studied either by ELISA or by Western blots. Neutrophil infiltration was observed by myeloperoxidase staining. FPR2 siRNA was used to knock down LXA4 receptor. The expression of endogenous LXA4 decreased, and the expression of FPR2 increased after SAH. Exogenous LXA4 decreased brain water content, reduced Evans blue extravasation, and improved neurological functions and improved the learning and memory ability after SAH. LXA4 reduced neutrophil infiltration and phosphorylation of p38, interleukin-1β, and interleukin-6. These effects of LXA4 were abolished by FPR2 siRNA. Exogenous LXA4 inhibited inflammation by activating FPR2 and inhibiting p38 after SAH. LXA4 may serve as an alternative treatment to relieve early brain injury after SAH.

Guo Z ，Hu Q ，Xu L ，Guo ZN ，Ou Y ，He Y ，Yin C ，Sun X ，Tang J ，Zhang JH ... -  《-》

LXA4 ameliorates cerebrovascular endothelial dysfunction by reducing acute inflammation after subarachnoid hemorrhage in rats.

Lipoxin A4 (LXA4) has been reported to reduce inflammation in experimental subarachnoid hemorrhage (SAH), but the mechanism remains unclear. In this study, we investigated the role of LXA4 in inflammation-mediated cerebrovascular endothelial dysfunction and the potential mechanism after SAH. SAH was induced by endovascular perforation in male Sprague-Dawley rats, and recombinant LXA4 was injected intracerebroventricularly 1.5 h after the operation. The expression changes in the markers of endothelial dysfunction (endothelial microparticles and nitric oxide) were analyzed by flow cytometry or Nitric Oxide (NO) assay kit. Microflow in the cerebral cortex was assayed by laser speckle contrast imaging. Neutrophil infiltration was observed by a marker of leukocyte activity (myeloperoxidase, MPO) that colocalized with a specific marker of endothelial cells (von Willebrand factor, VWF). The expression of LXA4 and its downstream molecules, formyl peptide receptor 2 (FPR2), extracellular signal-regulated kinase (ERK1/2), nuclear factor-κB (NF-κB), matrix metalloproteinase-9 (MMP9), and the levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), leukocyte adhesion molecule (intercellular adhesion molecule-1, ICAM-1) and MPO were measured either by Western blot or enzyme-linked immunosorbent assay (ELISA). SAH resulted in endothelial dysfunction and a reduction in microflow in the cerebral cortex. The expression of LXA4 was decreased, and the expression of pro-inflammatory factors (NF-κB, MMP9, ICAM-1, MPO) and cytokines (TNF-α, IL-1β, IL-6) was increased after SAH. The administration of LXA4 significantly ameliorated endothelial dysfunction, recovered microflow, and suppressed the inflammation and infiltration of neutrophils in SAH rats. The underlying mechanism of this outcome may involve the LXA4/FPR2/ERK1/2 pathway. LXA4 might be a promising candidate for acute SAH treatment.

Liu L ，Zhang P ，Zhang Z ，Hu Q ，He J ，Liu H ，Zhao J ，Liang Y ，He Z ，Li X ，Sun X ，Guo Z ... -  《-》

Lipoxin A(4) Suppresses IL-1β-Induced Cyclooxygenase-2 Expression Through Inhibition of p38 MAPK Activation in Endometriosis.

Dai S ，Zhu M ，Wu R ，Lin D ，Huang Z ，Ren L ，Huang S ，Cheng L ，Chen Q ... -  《-》

Airway lipoxin A4/formyl peptide receptor 2-lipoxin receptor levels in pediatric patients with severe asthma.

Lipoxins are biologically active eicosanoids with anti-inflammatory properties. Lipoxin A4 (LXA4) signaling blocks asthmatic responses in human and experimental model systems. There is evidence that patients with respiratory diseases, including severe asthma (SA), display defective generation of lipoxin signals despite glucocorticoid therapy. We investigated airway levels of formyl peptide receptor 2-lipoxin receptor (FPR2/ALXR), LXA4, and its counterregulatory compound, leukotriene B4 (LTB4), in patients with childhood asthma. We addressed the potential interplay of the LXA4-FPR2/ALXR axis and glucocorticoids in the resolution of inflammation. We examined LXA4 and LTB4 concentrations in induced sputum supernatants from children with intermittent asthma (IA), children with SA, and healthy control (HC) children. In addition, we investigated FPR2/ALXR expression in induced sputum cells obtained from the study groups. Finally, we evaluated in vitro the molecular interaction between LXA4 and glucocorticoid receptor-based mechanisms. We found that children with SA have decreased LXA4 concentrations in induced sputum supernatants in comparison with children with IA. In contrast to decreases in LXA4 concentrations, LTB4 concentrations were increased in children with asthma independent of severity. LXA4 concentrations negatively correlated with LTB4 concentrations and with exacerbation numbers in children with SA. FPR2/ALXR expression was reduced in induced sputum cells of children with SA compared with that seen in HC subjects and children with IA. Finally, we describe in vitro the existence of crosstalk between LXA4 and glucocorticoid receptor at the cytosolic level mediated by G protein-coupled FPR2/ALXR in peripheral blood granulocytes isolated from HC subjects, children with IA, and children with SA. Our findings provide evidence for defective LXA4 generation and FPR2/ALXR expression that, associated with increased LTB4, might be involved in a reduction in the ability of inhaled corticosteroids to impair control of airway inflammation in children with SA.

Gagliardo R ，Gras D ，La Grutta S ，Chanez P ，Di Sano C ，Albano GD ，Vachier I ，Montalbano AM ，Anzalone G ，Bonanno A ，Riccobono L ，Gjomarkaj M ，Profita M ... -  《-》

Lipoxin A4 Methyl Ester Reduces Early Brain Injury by Inhibition of the Nuclear Factor Kappa B (NF-κB)-Dependent Matrix Metallopeptidase 9 (MMP-9) Pathway in a Rat Model of Intracerebral Hemorrhage.

Song Y ，Yang Y ，Cui Y ，Gao J ，Wang K ，Cui J ... -  《MEDICAL SCIENCE MONITOR》