Phagocytosis of bacterial pathogens.
Phagocytosis is an evolutionarily ancient, receptor-driven process, by which phagocytic cells recognize invading microbes and destroy them after internalization. The phagocytosis receptor Eater is expressed exclusively on Drosophila phagocytes and is required for the survival of bacterial infections. In a recent study, we explored how Eater can defend fruit flies against different kinds of bacteria. We discovered that Eater bound to certain types of bacteria directly, while for others bacterial binding was dependent on prior disruption of the bacterial envelope. Similar to phagocytes, antimicrobial peptides and lysozymes are ancient components of animal immune systems. Our results suggest that cationic antimicrobial peptides, as well as lysozymes, can facilitate Eater binding to live Gram-negative bacteria. Both types of molecules promote surface-exposure of bacterial ligands that otherwise would remain buried and hidden under an outer membrane. We propose that unmasking ligands for phagocytic receptors may be a conserved mechanism operating in many animals, including humans. Thus, studying a Drosophila phagocytosis receptor may advance our understanding of innate immunity in general.
Department of Pediatrics, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Yoon-Suk Alexander
YS
Chung
Christine
C
Kocks
D000818:Animals; D004330:Drosophila / Q000276:immunology* / Q000382:microbiology; D029721:Drosophila Proteins / Q000276:immunology*; D006090:Gram-Negative Bacteria / Q000378:metabolism*; D010586:Phagocytes / Q000378:metabolism; D010587:Phagocytosis; D011956:Receptors, Cell Surface / Q000276:immunology*
D029721:Drosophila Proteins; D011956:Receptors, Cell Surface; C505820:eater protein, Drosophila