AUTHOR=Liu Hui , Cao Chun yuan , Qiu Fu lan , Huang Hao Nan , Xie Hongyan , Dong Renkang , Shi Yu Zhen , Hu Xiu Nian 

TITLE=Iron-Rich Conditions Induce OmpA and Virulence Changes of Acinetobacter baumannii

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.725194

DOI=10.3389/fmicb.2021.725194

ISSN=1664-302X

ABSTRACT=<p><bold>Background:</bold> Iron ions affect the expression of outer membrane protein A (OmpA), a major pathogenic protein in <italic>Acinetobacter baumannii.</italic></p><p><bold>Objective:</bold> To analyze the effect of iron ions on the expression of the OmpA protein of <italic>A. baumannii</italic> and explore its association with the virulence of OmpA.</p><p><bold>Methods:</bold> Site-directed mutagenesis was used to construct <italic>ompA</italic> gene deletion strains and gene repair strains. The OmpA protein expression of <italic>A. baumannii</italic> under culture with different contents of iron ions was detected. The virulence of <italic>A. baumannii</italic> with different OmpA protein expression levels were evaluated in macrophages and mice.</p><p><bold>Results:</bold> OmpA protein levels of the three strains were enhanced under iron-rich conditions. They were reduced in the presence of the iron-chelating agent 2,2′-bipyridine. <italic>A. baumannii</italic> wild type and + <italic>ompA</italic> had a remarkable toxic effect on RAW246.7 macrophages (<italic>P</italic> &lt; 0.05). In contrast, the Δ<italic>ompA</italic> had a significantly reduced toxic effect on RAW246.7 macrophages (<italic>P</italic> &lt; 0.05). The levels of the inflammatory factors IL-1β, IL-6, IL-8, and TNFα in the mice spleen were significantly increased in the + <italic>ompA</italic> strain treatment group compared with the Δ<italic>ompA</italic> strain group (all <italic>P</italic> &lt; 0.05). In addition, the levels were higher in the presence of iron ions than in the presence of the chelating agent.</p><p><bold>Conclusion:</bold> Iron-rich conditions increase the OmpA protein expression of <italic>A. baumannii</italic>. Strains with high OmpA protein expression were more invasive, which may be a key determinant of <italic>A. baumannii</italic> infection and pathogenicity. Iron control strategies might be used for the management of <italic>A. baumannii</italic>.</p>