Impact of Engagement of FcϵRI and CC Chemokine Receptor 1 on Mast Cell Activation and Motility

Abstract

Mast cells and basophils play an important role in IgEassociated allergic disorders and immune responses to parasites. Fc⑀RI cross-linking is a key event in the activation of mast cells and basophils. The Fc⑀RI is composed of three subunits: an ␣ chain, a ␤ chain, and a pair of ␥ chains, joined by a disulfide bond. The association of allergen with IgE bound to Fc⑀RI induces the transphosphorylation of cytoplasmic domains in the ␤-and ␥-chains called immunoreceptor tyrosinebased activation motifs via Lyn activation, which trigger signaling cascades leading to activation of kinases, phosphatases, or GTPases (1, 2). Fc⑀RI-mediated signaling induces a variety of events such as degranulation, increased gene transcription, and cytoskeleton rearrangement in mast cells and basophils (3, 4).Apart from the classical Fc⑀RI-mediated mechanism, mast cells and basophils are also activated by other substances such as chemokines and histamine-releasing factors (5, 6). Chemokines are a superfamily of small, structurally related cytokine molecules characterized by their ability to affect trafficking of immune cells. Some chemokines, such as CCL3 (macrophage inflammatory protein-1␣), CCL5 (RANTES), or CCL11 (eotaxin-1) have been reported to activate mouse, rat, or human mast cells and basophils in vitro (7-9) and in vivo (10, 11). In allergic inflammatory tissues, abundant expression of chemokines such as CCL3, CCL5, and CCL11 is observed both in the acute and late phase reactions (12, 13). It is therefore likely that Fc⑀RI and chemokine receptor engagement either occurs simultaneously or in relatively rapid succession in mast cells and basophils in vivo.Recently, Laffargue et al. (14) have shown that CCL3 or CCL5 significantly enhanced Fc⑀RI-mediated degranulation via phosphatidylinositol 3-kinase ␥-mediated signaling pathway in bone marrow-derived mast cells. The simultaneous engagement of Fc⑀RI and CC chemokine receptor (CCR) 1 appears to be important for optimal degranulation of mast cells in vitro and physiologically relevant levels of mast cell activation in vivo. However, it has not yet been established whether and how the simultaneous engagement of Fc⑀RI and CCR affects events other than degranulation of mast cells.In this paper, we show that costimulation via Fc⑀RI and CCR1 engagement synergistically enhances degranulation but inhibits CCL3-mediated chemotaxis using rat basophilic leukemia (RBL)-2H3 cells. Family members of the Rho-like GTPases, Rac, Cdc42, and Rho control cell motility by mediating the reorganization of the actin cytoskeleton (15-17). The costimulation via Fc⑀RI and CCR1 resulted in the imbalance of

Role of CCL7 in Type I Hypersensitivity Reactions in Murine Experimental Allergic Conjunctivitis

“…CCL3 was reported to stimulate human mast cell degranulation in vitro (16) and murine mast cell degranulation in vitro and in vivo (7,17). We found that treatment of mast cells with CCL3 and Ag results in greater degranulation than does cross-linking of FcεRI alone (8,17). Mice in which CCL3 is deficient or neutralized fail to display typical allergic symptoms after ocular exposure to allergen.…”

“…Because CCL7 is a ligand for CCR1, we examined whether CCL7 could stimulate CCR1 and contribute to mast cell activation in a manner similar to that observed for another ligand, CCL3 (8). RBL-CCR1 cells and BMMCs derived from wild-type mice, which both display characteristics of mucosal-type mast cells, express CCR1; RBL-CCR1 cells express CCR1 but no other CCRs, whereas BMMCs cultured with stem cell factor express CCR1-5 (43).…”

“…The cells were maintained at 3.5 3 10 5 cells per milliliter and cultured at 37˚C in 5% CO 2 . Culture medium was refreshed every 3 d. Geneticin (G-418 sulfate, 1 mg/ml) was added to the medium of RBL-CCR1 cells, as described previously (8). To generate primary bone marrow-derived mast cells (BMMCs), low-density mononuclear cells were isolated from CCL7 2/2 and wild-type mice and cultured in RPMI 1640 medium containing 10% FBS, 2 mM glutamine, 100 U/ml penicillin, 10 mg/ml streptomycin, 0.1 mM nonessential amino acids, 50 mM 2-ME, and 10 mM HEPES in the presence of 20 ng/ml recombinant murine IL-3 and 10 ng/ml recombinant murine stem cell factor (both from PeproTech) for 4-6 wk (39).…”

“…Two CCLs, CCL3/MIP-1a and CCL11/eotaxin-1, appear to have critical roles in regulating mast cells in ocular allergy. These ligands bind to CCR1 and CCR3, respectively, exerting effects on the maturation and activation of mast cells (7,8).…”

Evidence That Formation of Vimentin·Mitogen-activated Protein Kinase (MAPK) Complex Mediates Mast Cell Activation following FcεRI/CC Chemokine Receptor 1 Cross-talk

“…Moreover, CCL3 synergistically enhanced Fc⑀RI-mediated degranulation and gene expression of cytokines and chemokines (e.g. IL-6 and CCL7/MCP-3) in a rat basophilic leukemia 2H3 cell line (RBL-2H3) expressing CC chemokine receptor 1 (CCR1), a receptor for CCL3, and bone marrow-derived murine mast cells (11)(12)(13)(14). These observations indicate that (i) the simultaneous engagement of Fc⑀RI and CCR1 is important for optimal activation of mast cells in vitro and physiologically relevant levels of mast cell activation in vivo, and (ii) there is a cross-talk between the Fc⑀RI-mediated and CCR1-mediated signaling cascades.…”