Chemotaxis and Calcium Responses of Phagocytes to Formyl Peptide Receptor Ligands Is Differentially Regulated by Cyclic ADP Ribose

Abstract

Cyclic ADP ribose (cADPR) is a calcium-mobilizing metabolite that regulates intracellular calcium release and extracellular calcium influx. Although the role of cADPR in modulating calcium mobilization has been extensively examined, its potential role in regulating immunologic responses is less well understood. We previously reported that cADPR, produced by the ADP-ribosyl cyclase, CD38, controls calcium influx and chemotaxis of murine neutrophils responding to fMLF, a peptide agonist for two chemoattractant receptor subtypes, formyl peptide receptor and formyl peptide receptor-like 1. In this study, we examine whether cADPR is required for chemotaxis of human monocytes and neutrophils to a diverse array of chemoattractants. We found that a cADPR antagonist and a CD38 substrate analogue inhibited the chemotaxis of human phagocytic cells to a number of formyl peptide receptor-like 1-specific ligands but had no effect on the chemotactic response of these cells to ligands selective for formyl peptide receptor. In addition, we show that the cADPR antagonist blocks the chemotaxis of human monocytes to CXCR4, CCR1, and CCR5 ligands. In all cases, we found that cADPR modulates intracellular free calcium levels in cells activated by chemokines that induce extracellular calcium influx in the apparent absence of significant intracellular calcium release. Thus, cADPR regulates calcium signaling of a discrete subset of chemoattractant receptors expressed by human leukocytes. Since many of the chemoattractant receptors regulated by cADPR bind to ligands that are associated with clinical pathology, cADPR and CD38 represent novel drug targets with potential application in chronic inflammatory and neurodegenerative disease.

Abscisic acid is an endogenous cytokine in human granulocytes with cyclic ADP-ribose as second messenger

“…9D) and chemokinesis (data not shown) induced by ABA; moreover, the simultaneous addition of 20 mM nicotinamide with ABA completely inhibited ABA-stimulated chemokinesis (data not shown). Conversely, preincubation of granulocytes with 100 M 8-Br-cADPR, 50 M ryanodine, or 20 mM nicotinamide did not affect cell migration toward IL-8 (data not shown), which is known to stimulate chemotaxis in human granulocytes via a pathway not involving CD38/cADPR (8).…”

“…1B, trace 4) and ryanodine (data not shown) almost abolished the ABA-induced [Ca 2ϩ ] i increase, whereas they did not affect the Ca 2ϩ rise triggered by IL-8 (see SI Fig. 5C), which is known to induce Ca 2ϩ signaling in neutrophils via a pathway not involving cADPR (8). In line with this result, a minor role of IP 3 in the ABA-induced [Ca 2ϩ ] i rise was demonstrated by the effect of 10 M xestospongin, a specific IP 3 antagonist acting on the corresponding receptor channel (12), which decreased the [Ca 2ϩ ] i elevation by Ϸ15% (Fig.…”

“…This functional impairment of the CD38 Ϫ/Ϫ neutrophils is caused by absence of the cADPR-induced [Ca 2ϩ ] i increase. In addition, cADPR has been shown to regulate chemotaxis in human granulocytes and monocytes in response to different stimuli through a [Ca 2ϩ ] i increase (8,9).…”

FAM19A4 is a novel cytokine ligand of formyl peptide receptor 1 (FPR1) and is able to promote the migration and phagocytosis of macrophages

“…In addition, FPR1 is thought to play a role in sensing the endogenous signals of dysfunctional cells, which should attract leukocytes to the sites of inflammation and tissue damage. 11,22,23,25,26 As the ligand with the highest affinity for FPR1, fMLF has a Kd of 0.04 nM. 27 According to the ratio of Ki for fMLF (Ki50.08139 pM) and FAM19A4 (Ki558.81 pM) from the competition binding analysis, the Kd of FAM19A4 is 722 times that of fMLF.…”

Association analysis of formyl peptide receptor 2 (FPR2) polymorphisms and Aspirin exacerbated respiratory diseases

“…FPR2 is expressed by various kinds of inflammatory cells, including macrophages, monocytes, neutrophils, T lymphocytes, bronchial epithelial cells and microvascular endothelial cells. 16,17 These inflammatory cells are involved in the pathogenesis of asthma and in asthmatic subphenotypes, including aspirin hypersensitivity. On the basis of these biological functions, genetic alterations in FPR2 may be postulated to contribute to the pathophysiological processes of AERD.…”