Promoting detachment of neutrophils adherent to murine postcapillary venules to control inflammation: Effect of lipocortin 1

121

113

The appropriate development of an inflammatory response is central for the ability of a host to deal with any infectious insult. However, excessive, misplaced, or uncontrolled inflammation may lead to acute or chronic diseases. The microbiota plays an important role in the control of inflammatory responsiveness. In this study, we investigated the role of lipoxin A4 and annexin-1 for the IL-10-dependent inflammatory hyporesponsiveness observed in germfree mice. Administration of a 15-epi-lipoxin A4 analog or an annexin-1-derived peptide to conventional mice prevented tissue injury, TNF-α production, and lethality after intestinal ischemia/reperfusion. This was associated with enhanced IL-10 production. Lipoxin A4 and annexin-1 failed to prevent reperfusion injury in IL-10-deficient mice. In germfree mice, there was enhanced expression of both lipoxin A4 and annexin-1. Blockade of lipoxin A4 synthesis with a 5-lipoxygenase inhibitor or Abs against annexin-1 partially prevented IL-10 production and this was accompanied by partial reversion of inflammatory hyporesponsiveness in germfree mice. Administration of BOC-1, an antagonist of ALX receptors (at which both lipoxin A4 and annexin-1 act), or simultaneous administration of 5-lipoxygenase inhibitor and anti-annexin-1 Abs, was associated with tissue injury, TNF-α production, and lethality similar to that found in conventional mice. Thus, our data demonstrate that inflammatory responsiveness is tightly controlled by the presence of the microbiota and that the innate capacity of germfree mice to produce IL-10 is secondary to their endogenous greater ability to produce lipoxin A4 and annexin-1.

Section: Analogue Atl-1 or The Anxa-1-derived Peptide Ac2-26 Does Notmentioning

confidence: 99%

The Required Role of Endogenously Produced Lipoxin A4 and Annexin-1 for the Production of IL-10 and Inflammatory Hyporesponsiveness in Mice

Souza¹,

Fagundes²,

Amaral³

et al. 2007

121

113

“…Briefly, 1 ϫ 10 6 U937 cells were radiolabeled by incubation in 100 l of RPMI containing 10% FCS and 20 Ci of 51 Cr (as sodium chromate) for 1 h at 37°C. After washing three times with HBSS labeled U937 cells were resuspended in RPMI 1640 medium containing 10% FCS, and were then incubated at 37°C for 30 min with or without human rANX1 (6). Next, 200 l (2 ϫ 10 5 ) labeled U937 cells, treated or not with ANX1, were added to each well of 96-well plates containing confluent HBMEC monolayers.…”

Section: Adhesion Of U937 Cells To Endothelial Cellsmentioning

confidence: 99%

“…Recombinant ANX1, annexin 5 (ANX5), and a chimeric protein ANX1-5, were expressed as GST-fusion proteins in pGEX vectors, as described (6). Fusion proteins were purified from bacterial lysates by affinity chromatography using prepacked glutathione-Sepharose 4B, and the GST moiety was removed by cleavage with thrombin (20).…”

Section: Abs Recombinant Proteins and Peptidesmentioning

confidence: 99%

“…Conversely, lowering endogenous steroids by adrenalectomy or by a sustained treatment with the steroid antagonist mifepristone (RU486) reduced the amount of cell-associated ANX1 protein and mRNA by ϳ50% (4). In inflammatory models, exogenous ANX1 inhibited recruitment of polymorphonuclear (PMN) leukocytes in vivo (5,6). Moreover, treatments with Ab to ANX1 blocked the anti-inflammatory effect of dexamethasone in animal models of acute inflammation (7).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Annexin 1 Binds to U937 Monocytic Cells and Inhibits Their Adhesion to Microvascular Endothelium: Involvement of the α4β1 Integrin

Solito

Romero

Marullo

et al. 2000

Self Cite

Annexin 1 (ANX1), a calcium-binding protein, participates in the regulation of early inflammatory responses. Whereas some of its effects depend on intracellular interactions, a growing number of observations indicate that ANX1 may also act via autocrine/paracrine functions following externalization to the outer side of the plasma membrane. We studied the effects of ANX1 on leukocyte adhesion to endothelial cells using as a model system the monocytic cell line U937 and human bone marrow microvascular endothelial cells. Exogenous rANX1, as well as endogenous ANX1 externalized by U937 differentiated in vitro, inhibited monocyte firm adhesion to vascular endothelium. Both binding of ANX1 to U937 cells and ANX1-mediated inhibition of cell adhesion involved the short N-terminal domain of the ANX1 molecule. Under experimental conditions in which ANX1 inhibited U937 adhesion to human bone marrow microvascular endothelial cells, this protein specifically colocalized with the α4 integrin, and a direct interaction between ANX1 and the α4 integrin could be documented by immunoprecipitation experiments. Moreover, ANX1 competed with the endothelial integrin counterreceptor, VCAM-1, for binding to α4 integrin. These results indicate that ANX1 plays an important physiological role in modulating monocyte firm adhesion to the endothelium.

“…The anti-inflammatory activities elicited by exogenously applied annexin 1 are mediated through its unique N-terminal domain. Peptides derived from this domain, which are most likely generated at sites of inflammation and in coculture of neutrophils with activated endothelial cells, are not only true mimetics of the annexin 1 action in all inflammation models tested, but most likely are also the active entities with respect to the antiinflammatory actions described for annexin 1 (5,(7)(8)(9)(10)(11). Recently, it was shown that the inhibitory effect of the N-terminal annexin 1 peptides as well as full-length annexin 1 on the transendothelial migration of granulocytes is at least in part due to a peptidetriggered desensitization of the N-formyl peptide receptor (FPR) 3 on human granulocytes.…”

mentioning

confidence: 99%

An Annexin 1 N-Terminal Peptide Activates Leukocytes by Triggering Different Members of the Formyl Peptide Receptor Family

Ernst¹,

Lange²,

Wilbers³

et al. 2004

143

144

The human N-formyl peptide receptor (FPR) is a key modulator of chemotaxis directing granulocytes toward sites of bacterial infections. FPR is the founding member of a subfamily of G protein-coupled receptors thought to function in inflammatory processes. The other two members, FPR-like (FPRL)1 and FPRL2, have a greatly reduced affinity for bacterial peptides or do not bind them at all, with FPRL2 being considered an orphan receptor so far. In this study we show that a peptide derived from the N-terminal domain of the anti-inflammatory protein annexin 1 (lipocortin 1) can activate all three FPR family members at similar concentrations. The annexin 1 peptide initiates chemotactic responses in human monocytes that express all three FPR family members and also desensitizes the cells toward subsequent stimulation with bacterial peptide agonists. Experiments using HEK 293 cells stably expressing a single FPR family member reveal that all three receptors can be activated and desensitized by the N-terminal annexin 1 peptide. These observations identify the annexin 1 peptide as the first endogenous ligand of FPRL2 and indicate that annexin 1 participates in regulating leukocyte emigration into inflamed tissue by activating and desensitizing different receptors of the FPR family.