Mechanisms of Allergy
Selective modulation of chemokinesis, degranulation, and apoptosis in eosinophils through the PGD2 receptors CRTH2 and DP

https://doi.org/10.1067/mai.2001.119919Get rights and content

Abstract

Background: PGD2 is the major prostanoid released by mast cells during an allergic response. Its role in the allergic response, however, remains unclear. Objective: Because the accumulation of eosinophils is a feature of allergic reactions, we investigated the role of PGD2 in the modulation of eosinophil function. Methods: Circulating human eosinophils were isolated and challenged with PGD2. The effects of PGD2 on various eosinophil functions were then analyzed. Results: PGD2 binds with high affinity preferentially to 2 receptors, DP and chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2). We show that both DP and CRTH2 are detectable on circulating eosinophils. We demonstrate that PGD2 (1-10 nmol/L) induces a rapid change in human eosinophil morphology and an increase in chemokinesis and promotes eosinophil degranulation. These effects are induced by the CRTH2-selective agonist 13-14-dihydro-15-keto-PGD2 (DK-PGD2) but not by the DP-selective agonist BW245C. These results suggest a role for CRTH2 in the modulation of eosinophil movement and in triggering the release of cytotoxic proteins. Finally, we demonstrate that BW245C, but not DK-PGD2, can delay the onset of apoptosis in cultured eosinophils, presumably through interaction with DP. Conclusion: These data support the hypothesis that PGD2 controls eosinophil functions through 2 pharmacologically distinct receptors with independent functions. Blockade of PGD2-mediated effects on human eosinophils may reduce the damage caused by these cells during an allergic response, but inhibition of both receptors may be required. (J Allergy Clin Immunol 2001;108:982-8.)

Section snippets

Reagents

PGD2, fluprostenol, and PGE2 were obtained from Biomol Research Laboratories. BW245C, 13,14-dihydro-15-keto-PGD2 (DK-PGD2), and latanoprost (free acid) were from Cayman Chemical. Platelet-activating factor (PAF) was from Sigma. Recombinant human IL-5 was produced at the Merck Frosst Centre for Therapeutic Research by using a baculovirus system and purified by means of fast performance liquid chromatography.10

Eosinophil purification

Circulating eosinophils were isolated from heparinized venous blood from healthy

Human eosinophils express both DP and CRTH2

RT-PCR was performed on total RNA from human eosinophils (>95% purity) to establish which PGD2-binding receptors are expressed by human eosinophils. The identity of the PCR products was confirmed by means of Southern blot detection with DP- and CRTH2-specific probes. CRTH2 and DP mRNA were detected in eosinophils from all 7 donors tested. Results from 3 donors are shown in Fig 1.

. Both DP and CRTH2 mRNA are detected by means of RT-PCR/Southern hybridization in human eosinophils. RNA from HEK

Discussion

PGD2 interacts preferentially with 2 GPCRs: DP and CRTH2. We have shown that in eosinophils, shape change, chemokinesis, and degranulation are induced by both PGD2 and DK-PGD2. In contrast, PGD2 and BW245C have antiapoptotic effects on cultured eosinophils. BW245C21 and DK-PGD28 are reported to be highly selective agonists for DP and CRTH2, respectively, and PGD2 has similar affinity for CRTH2 and DP.22 Taken together, these data strongly suggest that CRTH2 mediates shape change, chemokinesis,

Acknowledgements

We thank Betty Stamatiou for her eosinophil isolation protocol; Denis Normandin and Simon Wong for the evaluation of eosinophil purity; Dr Donald W. Nicholson and Mike Scheid for the generation of rIL-5; Dr Bruce Daugherty, Dr John Mudgett, and Marco Soares for help with the chemokinesis assay; Diane Ethier for technical assistance with the FACS; Grace Konrath for technical assistance; and Deborah Slipetz for statistical analysis of the data.

References (33)

  • LJd Roberts et al.

    Increased production of prostaglandin D2 in patients with systemic mastocytosis

    N Engl J Med

    (1980)
  • RA Lewis et al.

    Prostaglandin D2 generation after activation of rat and human mast cells with anti-IgE

    J Immunol

    (1982)
  • M. Willis-Karp

    Immunological basis of antigen-induced airway hyperresponsiviness

    Annu Rev Immunol

    (1999)
  • RI Abu-Ghazaleh et al.

    Eosinophil granule proteins in peripheral blood granulocytes

    J Leukoc Biol

    (1992)
  • DL Emery et al.

    Prostaglandin D2 causes accumulation of eosinophils in the lumen of the dog trachea

    J Appl Physiol

    (1989)
  • EJ Goetzl et al.

    Biochemical and functional bases of the regulatory roles of the human eosinophils

  • Cited by (229)

    View all citing articles on Scopus

    Reprint requests: Francois G. Gervais, PhD, Department of Biochemistry and Molecular Biology, Merck Frosst Centre for Therapeutic Research, PO Box 1005, Kirkland, Quebec, Canada, H9R 4P8.

    View full text