The HopQ-CEACAM Interaction Controls CagA Translocation, Phosphorylation, and Phagocytosis of <i>Helicobacter pylori</i> in Neutrophils

Abstract

The <i>cag</i> type IV secretion system (<i>cag</i>-T4SS) of <i>Helicobacter pylori</i> exploits specific cellular carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), such as CEACAM1, -3, -5, and -6, as cellular receptors for CagA translocation into human gastric epithelial cells. We studied the interaction of <i>H. pylori</i> with human CEACAM1, CEACAM3, and CEACAM6 receptors (hCEACAMs) expressed on myeloid cells from CEACAM-humanized mice. Human and CEACAM-humanized mouse polymorphonuclear neutrophils (PMNs) allowed a specific HopQ-dependent interaction strongly enhancing CagA translocation. Translocated CagA was tyrosine phosphorylated, which was not seen in wild-type (wt) murine neutrophils. In contrast, human or murine bone marrow-derived macrophages and dendritic cells (DCs) revealed a low hCEACAM expression and bacterial binding. CagA translocation and tyrosine-phosphorylation was low and independent of the HopQ-CEACAM interaction. Neutrophils, but not macrophages or DCs, from CEACAM-humanized mice, significantly upregulated the proinflammatory chemokine MIP-1α. However, macrophages showed a significantly reduced amount of CXCL1 (KC) and CCL2 (MCP-1) secretion in CEACAM-humanized versus wt cells. Thus, <i>H. pylori</i>, via the HopQ-CEACAM interaction, controls the production and secretion of chemokines differently in PMNs, macrophages, and DCs. We further show that upon <i>H. pylori</i> contact the oxidative burst of neutrophils and phagocytosis of <i>H. pylori</i> was strongly enhanced, but hCEACAM3/6 expression on neutrophils allowed the extended survival of <i>H. pylori</i> within neutrophils in a HopQ-dependent manner. Finally, we demonstrate that during a chronic mouse infection, <i>H. pylori</i> is able to systemically downregulate hCEACAM1 and hCEACAM6 receptor expression on neutrophils, probably to limit CagA translocation efficiency and most likely gastric pathology.<b>IMPORTANCE</b><i>Helicobacter pylori</i> is highly adapted to humans and evades host immunity to allow its lifelong colonization. However, the <i>H. pylori</i> mouse model is artificial for <i>H. pylori</i>, and few adapted strains allow gastric colonization. Here, we show that human or CEACAM-humanized, but not mouse neutrophils are manipulated by the <i>H. pylori</i> HopQ-CEACAM interaction. Human CEACAMs are responsible for CagA phosphorylation, activation, and processing in neutrophils, whereas CagA translocation and tyrosine phosphorylation in DCs and macrophages is independent of the HopQ-CEACAM interaction. <i>H. pylori</i> affects the secretion of distinct chemokines in CEACAM-humanized neutrophils and macrophages. Most importantly, human CEACAMs on neutrophils enhance binding, oxidative burst, and phagocytosis of <i>H. pylori</i> and enhance bacterial survival in the phagosome. The <i>H. pylori</i>-CEACAM interaction modulates PMNs to reduce the <i>H. pylori</i> CagA translocation efficiency <i>in vivo</i> and to fine-tune the expression of CEACAM receptors on neutrophils to limit translocation of CagA and gastric pathology.