期刊
FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY
卷 8, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fcimb.2018.00192
关键词
Q fever; Coxiella burnetii; LpxC inhibitor; LPC-011; lipid A; LPS
资金
- National Key R&D Program of China [2016YFC1202705]
- National Natural Science Foundation of China [31570177]
- Foundation of State Key Laboratory of Pathogen and Biosecurity [SKLPBS1409]
- National Institute of General Medical Sciences, USA [GM115355]
Lipid A is an essential basal component of lipopolysaccharide of most Gram-negative bacteria. Inhibitors targeting LpxC, a conserved enzyme in lipid A biosynthesis, are antibiotic candidates against Gram-negative pathogens. Here we report the characterization of the role of lipid A in Coxiella burnetii growth in axenic media, monkey kidney cells (BGMK and Vero), and macrophage-like THP-1 cells by using a potent LpxC inhibitor -LPC-011. We first determined the susceptibility of C. burnetii LpxC to LPC-011 in a surrogate C. coil model. In E. coll., the minimum inhibitory concentration (MIC) of LPC-011 against C. burnetii LpxC is <0.05 mu g/mL, a value lower than the inhibitor's MIC against E. coil LpxC. Considering the inhibitor's problematic pharmacokinetic properties in vivo and Coxiella's culturing time up to 7 days, the stability of LPC-011 in cell cultures was assessed. We found that regularly changing inhibitor-containing media was required for sustained inhibition of C. burnetii LpxC in cells. Under inhibitor treatment, Coxiella has reduced growth yields in axenic media and during replication in non-phagocytic cells, and has a reduced number of productive vacuoles in such cells. Inhibiting lipid A biosynthesis in C. burnetii by the inhibitor was shown in a phase II strain transformed with chlamydial kdtA. This exogenous KdtA enzyme modifies Coxiella lipid A with an alpha-Kdo-(2 -> 8)-alpha-Kdo epitope that can be detected by anti-chlamydia genus antibodies. In inhibitor-treated THP-1 cells, Coxiella shows severe growth defects characterized by poor vacuole formation and low growth yields. Coxiella progenies prepared from inhibitor-treated cells retain the capability of normally infecting all tested cells in the absence of the inhibitor, which suggests a dispensable role of lipid A for infection and early vacuole development. In conclusion, our data suggest that lipid A has significance for optimal development of Coxiella-containing vacuoles, and for robust multiplication of C. burnetii in macrophage-like THP-1 cells. Unlike many bacteria, C. burnetii replication in axenic media and non-phagocytic cells was less dependent on normal lipid A biosynthesis.
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