Acinetobacter baumannii invades epithelial cells and outer membrane protein A mediates interactions with epithelial cells.
BACKGROUND
Acinetobacter baumannii is a nosocomial pathogen of increasing importance, but the pathogenic mechanism of this microorganism has not been fully explored. This study investigated the potential of A. baumannii to invade epithelial cells and determined the role of A. baumannii outer membrane protein A (AbOmpA) in interactions with epithelial cells.


RESULTS
A. baumannii invaded epithelial cells by a zipper-like mechanism, which is associated with microfilament- and microtubule-dependent uptake mechanisms. Internalized bacteria were located in the membrane-bound vacuoles. Pretreatment of recombinant AbOmpA significantly inhibited the adherence to and invasion of A. baumannii in epithelial cells. Cell invasion of isogenic AbOmpA- mutant significantly decreased as compared with wild-type bacteria. In a murine pneumonia model, wild-type bacteria exhibited a severe lung pathology and induced a high bacterial burden in blood, whereas AbOmpA- mutant was rarely detected in blood.


CONCLUSIONS
A. baumannii adheres to and invades epithelial cells. AbOmpA plays a major role in the interactions with epithelial cells. These findings contribute to the understanding of A. baumannii pathogenesis in the early stage of bacterial infection.
Choi
Chul Hee
CH
Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Korea. chchoi@knu.ac.kr
Lee
Jun Sik
JS
Lee
Yoo Chul
YC
Park
Tae In
TI
Lee
Je Chul
JC
D000151:Acinetobacter Infections / Q000378:metabolism*; D040981:Acinetobacter baumannii / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D018407:Bacterial Physiological Phenomena / Q000187:drug effects; D002460:Cell Line; D015638:Cytochalasin D / Q000494:pharmacology; D004847:Epithelial Cells / Q000382:microbiology*; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D014747:Vinblastine / Q000494:pharmacology
D001425:Bacterial Outer Membrane Proteins; C078167:OMPA outer membrane proteins; D015638:Cytochalasin D; D014747:Vinblastine