Brain angiogenesis inhibitor 1 is expressed by gastric phagocytes during infection with Helicobacter pylori and mediates the recognition and engulfment of.
The FASEB Journal • Research Communication
Brain angiogenesis inhibitor 1 is expressed by gastric phagocytes during infection with Helicobacter pylori and mediates the recognition and engulfment of human apoptotic gastric epithelial cells Soumita Das,*,1 Arup Sarkar,*,1 Kieran A. Ryan,‡,§,1 Sarah Fox,* Alice H. Berger,储,¶ Ignacio J. Juncadella,#,** Diane Bimczok,††,‡‡ Lesley E. Smythies,††,‡‡ Paul R. Harris,§§ Kodi S. Ravichandran,#,** Sheila E. Crowe,† Phillip D. Smith,††,‡‡ and Peter B. Ernst*,2 *Division of Comparative Pathology and Medicine, Department of Pathology, and †Department of Medicine, University of California, San Diego, San Diego, California, USA; ‡Department of Microbiology and §Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; 储Cancer Program, Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, Massachusetts, USA; ¶Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA; #Department of Microbiology and **Beirne Carter Center for Immunology, University of Virginia, Charlottesville, Virginia, USA; ††Department of Medicine and ‡‡ Department of Gastroenterology, University of Alabama at Birmingham, Birmingham, Alabama, USA; and §§Division of Pediatrics, Unit of Gastroenterology and Nutrition, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile After Helicobacter pylori infection in humans, gastric epithelial cells (GECs) undergo apoptosis due to stimulation by the bacteria or inflammatory cytokines. In this study, we assessed the expression and function of brain angiogenesis inhibitor 1 (BAI1) in the engulfment of apoptotic GECs using human tissue and cells. After induction of apoptosis by H. pylori or camptothecin, there was a 5-fold increase in the binding of apoptotic GECs to THP-1 cells or peripheral blood monocyte-derived macrophages as assayed by confocal microscopy or conventional and imaging flow cytometry. Binding was impaired 95% by pretreating apoptotic cells with annexin V, underscoring the requirement for phosphatidylserine recognition. The phosphatidylserine receptor BAI1 was expressed in human gastric biopsy specimens and gastric phagocytes. To confirm the role of BAI1 in apoptotic cell clearance, the functional domain of BAI1 was used as a competitive inhibitor or BAI1 expression was inhibited by small interfering RNA. Both approaches decreased binding and engulfment >40%. Exposing THP-1 cells to apoptotic cells inhibited IL-6 production from 1340 to
ABSTRACT
Abbreviations: BAI1, brain angiogenesis inhibitor 1; CFSE, 5-(and 6)-carboxyfluorescein diacetate succinimidyl ester; DMEM, Dulbecco’s modified Eagle’s medium; Dock180, dedicator of cytokinesis 180; ELMO1, engulfment and cell motility protein 1; GEC, gastric epithelial cell; GM-CSF, granulocyte-macrophage colony-stimulating factor; GST, glutathione S-transferase, IL-6, interleukin-6; LPS, lipopolysaccharide; MDM, monocyte-derived macrophage; MOI, multiplicity of infection; PBS, phosphate-buffered saline; PMA, phorbol 12-myristate 13-acetate; PS, phosphatidylserine; siRNA, small interfering RNA; TSR, thrombospondin repeat 2214
