Activation of Phosphatase and Tensin Homolog on Chromosome 10 Mediates the Inhibition of FcR Phagocytosis by Prostaglandin E 2 in Alveolar Macrophages 1 Claudio Canetti, 2 * ‡ Carlos H. Serezani, 2 * Rachelle G. Atrasz,* Eric S. White,* David M. Aronoff, † and Marc Peters-Golden 3 * PGE 2 has important inhibitory effects on the macrophage host defense functions of phagocytosis and killing, yet the molecular mechanisms involved remain to be fully elucidated. PGE 2 causes an elevation of cAMP in alveolar macrophages (AMs), which in turn activates the cAMP effector targets, protein kinase A and the exchange protein activated by cAMP (Epac)-1. We now report that FcR-induced PI3K/Akt and ERK-1/2 activation are inhibited by PGE 2 in AMs. By specifically inhibiting the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in AMs, we attenuated the inhibitory effects of both PGE 2 and a specific Epac-1 agonist (8-pCPT-2-O-Me-cAMP) on FcR-mediated phagocytosis and Akt/ERK-1/2 activation; PTEN inhibition also decreased PGE 2 -induced suppression of bacterial killing by AMs. Moreover, PGE 2 and the Epac-1 agonist induced an increase in PTEN lipid phosphatase activity, and this was associated with decreased tyrosine phosphorylation on PTEN—a mechanism known to regulate PTEN activity. Using a pharmacological approach, we demonstrated a role for Src homology 2-containing protein tyrosine phosphatase-1 in the PGE 2 -induced tyrosine dephosphorylation of PTEN. Collectively, these data reveal that PGE 2 , via Epac-1 activation, enhances SHP-1 activity, resulting in increased PTEN activity. We suggest that this mechanism contributes to the ability of PGE 2 to inhibit PI3K-dependent innate immune signaling in primary macrophages. The Journal of Immunology, 2007, 179: 8350 – 8356. M acrophages are key cellular participants in innate im- munity, recognizing and ingesting pathogenic micro- organisms through both opsonin-dependent and -inde- pendent pathways. Among several mechanisms that macrophages use to internalize microbes, FcR-mediated phagocytosis is an im- portant primary mode of defense in the immune system. Accom- panying phagocytosis is the generation of reactive oxygen inter- mediates and reactive nitrogen intermediates, which facilitate the intracellular killing of ingested pathogens, as well as the produc- tion of inflammatory mediators (e.g., cytokines, chemokines, and lipids) that enhance immune responses by recruiting and activating polymorphonuclear leukocytes. These inflammatory responses are teleologically advantageous, but when unregulated or severe, lead to tissue damage with associated morbidity and mortality of the infected host. Thus, these proinflammatory signals must be bal- anced with counterregulatory anti-inflammatory signals generated during infection to reign in the inflammatory response and ensure its resolution when the microbial threat is cleared. Within the mac- rophage, a series of complex cascades of reactions is evoked upon ligation and cross-linking of the FcR, including several mediated by kinases and phosphatase enzymes that dictate the vigor of the subsequent inflammatory response. Recent advances in this area include the recognition that FcR phagocytosis is negatively reg- ulated by protein Tyr phosphatases as well as inositol phosphatases (1–5). The phagocytosis of IgG-opsonized targets by the macrophage is initiated when the Fc portion of IgG binds to and clusters the FcR on the surface of the phagocytic cell (reviewed by Swanson and Hoppe in Ref. 6). This provokes the phosphorylation of FcR- associated ITAMs by kinases of the Src family, thereby initiating the local assembly of signaling enzymes and adapter-enzyme com- plexes necessary for successful phagocytosis and the generation of inflammatory mediators (6). One of the crucial participants in FcR signaling and particle ingestion is PI3K, a lipid kinase that phosphorylates the inositol ring at the 3' position, generating sev- eral products including phosphatidylinositol 3,4,5-triphosphate (PIP3). 4 PIP3 is necessary for the recruitment and activation of pleckstrin homology domain-containing enzymes such as the gua- nine exchange factor Vav and the Ser/Thr kinase Akt (protein ki- nase B) (7). The phagocytic actions of PI3K are countered by the inositol 3-phosphatase and tensin homolog on chromosome 10 (PTEN) (8). PTEN is a protein/lipid phosphatase that can dephosphorylate PIP3 at the D3 position (9). Studies of transfected cells demonstrate that *Division of Pulmonary and Critical Care Medicine and † Division of Infectious Dis- eases, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, MI 48109; and ‡ Instituto de Biofı ´sica Carlos Chagas Filho, Universidade Fed- eral do Rio de Janeiro, Rio de Janeiro, Brazil Received for publication April 26, 2007. Accepted for publication October 1, 2007. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1 This work was supported by National Institutes of Health Grants HL078727 (to D.M.A.) and HL058897 (to M.P.-G.), American Lung Association Research Grant RG8909N (to D.M.A.), Conselho Nacional de Desenvolvimento Cientı ´fico e Tecno- lo ´gico (to C.C.), and Coordenac ¸a ˜o de Aperfeic ¸oamento de Pessoal de Nı ´vel Superior (to C.C.). 2 C.C. and C.H.S. contributed equally to this work. 3 Address correspondence and reprint requests to Dr. Marc Peters-Golden, University of Michigan Health System, 6301 Medical Science Research Building III, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5642. E-mail address: petersm@ umich.edu 4 Abbreviations used in this paper: PIP3, phosphatidylinositol 3,4,5-triphosphate; PTEN, phosphatase and tensin homolog deleted on chromosome 10; AM, alveolar macrophage; Epac-1, exchange protein activated by cAMP-1; PKA, protein kinase A; SHP-1, Src homology 2-containing protein tyrosine phosphatase-1; SHPI, -bromo-4-(carboxymethoxy)-acetophenone. Copyright © 2007 by The American Association of Immunologists, Inc. 0022-1767/07/$2.00 The Journal of Immunology www.jimmunol.org