Inhibition of neutrophil migration in mice by mouse formyl peptide receptors 1 and 2 dual agonist: indication of cross-desensitization in vivo

Abstract

Summary It has been reported that the stimulation of neutrophils with N‐formyl‐Met‐Leu‐Phe (fMLF), an agonist for formyl peptide receptor (Fpr) 1, renders cells unresponsive to other chemoattractants in vitro. This is known as cross‐desensitization, but its functional relevance in neutrophil migration in vivo has not been investigated. Here, we show that precedent stimulation of mouse neutrophils with compound 43, a non‐peptidyl agonist for mouse Fpr1 and Fpr2, rendered the cells unresponsive to a second stimulation with C5a, leukotriene B4, or keratinocyte‐derived cytokine (KC) in calcium mobilization and chemotaxis assays in vitro. The expression of chemokine (C‐X‐C motif) receptor 2 (CXCR2) on the surface of neutrophils was concomitantly diminished by stimulating the cells with the compound. Moreover, oral administration of the compound to mice before they were exposed to lipopolysaccharide (LPS) aerosol resulted in a dose‐dependent reduction in the neutrophil count in bronchoalveolar lavage fluid. The expression of CXCR2 on blood neutrophils was also reduced in the compound‐administered mice. The recipient mice that underwent adoptive transfer of fluorescence‐labelled neutrophils that had been incubated with the compound showed a substantial decrease in neutrophil counts in bronchoalveolar lavage fluid after they were exposed to LPS, when compared with the control mice to which vehicle‐treated neutrophils had been transferred. These results are consistent with the idea that the agonist for Fpr1 and Fpr2 induced cross‐desensitization in neutrophils and attenuated neutrophil migration into the airways. Our results also revealed the unpredicted effect of an Fpr1 and Fpr2 dual agonist, which may act as a functional antagonist for multiple chemoattractant receptors in vivo.

Airway Activation of Formyl Peptide Receptors Inhibits Th1 and Th17 Cell Responses via Inhibition of Mediator Release from Immune and Inflammatory Cells and Maturation of Dendritic Cells

“…However, previous data showed that activation of FPRs inhibited migration of neutrophils through the desensitization of other chemokine receptors (29,30). As endogenous agonists, LXA4 and its metabolite 15-epi-LXA4 bind to FPRL1 and act as potent anti-inflammatory molecules that inhibit neutrophil chemotaxis, adherence, diapedesis, cytokine production, and superoxide generation (16,31).…”

A formyl peptide receptor agonist suppresses inflammation and bone damage in arthritis

“…Cpd43 was developed as a ligand for FPR2, and has been shown to inhibit neutrophil chemotaxis and markedly reduce mouse ear inflammation (Burli et al, 2006;Sogawa et al, 2011). Alterations in the structure of FPR2 prevent the action of Cpd43, suggesting the presence of specific sites on FPR2 with which Cpd43 interacts (Bena et al, 2012), although this has not been demonstrated physically, for example, using crystallography.Notably, in human neutrophils, Cpd43 has been reported to interact with both FPR1 and FPR2 (Forsman et al, 2011), suggesting that, in at least some conditions, it is a FPR1/2 dual agonist.…”

“…In vivo, Cpd43 exerts anti-inflammatory effects in murine ear inflammation and air-pouch models, which require FPR2 (Burli et al, 2006;Dufton et al, 2010;Sogawa et al, 2011). Mutation studies have identified specific domains in FPR2, which are required for the action of Cpd43 (Bena et al, 2012), but in human neutrophils, Cpd43 has also been reported to interact with FPR1 (Forsman et al, 2011).…”

The proteolytically stable peptidomimetic Pam-(Lys-βNSpe)6-NH2 selectively inhibits human neutrophil activation via formyl peptide receptor 2

“…Activation of neutrophils through FPRs induces a variety of pro-inflammatory and antibacterial effector mechanisms including production of ROS, and release of antimicrobial peptides (AMPs) and hydrolytic enzymes from intracellular granules [20]. Furthermore, FPRs regulate the inflammatory reactions in neutrophils by modulating signaling through many other receptors in a process termed receptor cross-talk [21][22][23][24]. The role of FPRs in regulation of inflammation is highlighted by their suggested involvement in both systemic [25] and local [26][27][28] inflammatory responses.…”