Acinetobacter baumannii invades epithelial cells and outer membrane protein A mediates interactions with epithelial cells

Abstract

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.

Insights into Acinetobacter baumannii pathogenicity

“…However, rates of bacteremia were less at 24 H in the pld mutant, and subsequent bacterial burden in extra-pulmonary tissues (heart and liver) was also less (24). These results are similar to that observed for OmpA in a murine pneumonia model, where the mutant strain had similar lung densities to the wild-type, but lung inflammation and tissue destruction, as well as bacterial burden in the blood, were less for the mutant (16).…”

“…Furthermore, Omp38 was shown to degrade chromosomal DNA by DNAse Ilike enzymatic activity (36). Finally, in a murine pneumonia model, the OmpA 2 mutant produced less lung inflammation and tissue destruction, and a lower bacterial density in blood (16). Other studies have also implicated OmpA in pathogenesis, including toxicity toward the human fungal pathogen Candida albicans (17).…”

“…OmpA localized to the mitochondria, causing damage and activation of caspases and apoptosis-inducing factors (14). This work was extended to show that Omp38 binds to a range of eukaryotic cells (HEp-2, Cos-7, and macrophages), is important for A. baumannii cellular invasion, and that it targets both the nucleus and mitochondria (15,16). Furthermore, Omp38 was shown to degrade chromosomal DNA by DNAse Ilike enzymatic activity (36).…”

“…Another outer membrane protein that has been implicated in biofilm formation is OmpA (14)(15)(16)(17). It appears that OmpA is not essential for biofilm development, but is required for the formation of thick biofilms on polystyrene (17).…”

Are we closing in on an "elusive enemy"? The current status of our battle withAcinetobacter baumannii

“…Omps have also been advanced as potential targets for diagnosis of A. baumannii, as they elicit specific IgG, IgM and IgG antibodies. [26][27][28][29] Of tremendous import, an Omp vaccine with multiple surface antigens from the bacterial membrane of A. baumannii elicited protective and therapeutic humoral and cellular responses in a murine sepsis model. 30 How well will this serve as a start to a vaccine remains to be seen.…”