Differences and similarities in permissive A/J versus non-permissive BALB/c murine macrophages infected with Legionella pneumophila: The role of iron

Abstract

Legionella pneumophila, a facultative intracellular pathogen, replicates within and kills thioglycolate-elicited (TG) macrophages from A/J mice, while growth is inhibited in TG macrophages from BALB/c mice which show no impaired viability. The role of iron in BALB/c and A/J macrophages regarding their permissiveness to L. pneumophila intracellular growth was investigated. We previously reported that TG macrophages from the A/J mouse strain readily supported the intracellular growth of L. pneumophila, while resident macrophages from the same strain of mice were not permissive. Recently we also found that such a difference in permissiveness between both A/J macrophage populations may be explained, at least in part, to intracellular availability of iron. In this report, differences in permissiveness to L. pneumophila growth between A/J TG macrophages and BALB/c TG macrophages was not due to intracellular iron availability. BALB/c and A/J TG macrophages exhibited similar expression of transferrin receptor and cellular iron content. The treatment of BALB/c TG macrophages with different iron compounds, namely ferric nitrilotriacetate (12.5-100 microM), ferric citrate (12.5-100 microM) and transferrin (0.5-5 mg ml-1), did not stimulate the intracellular proliferation of L. pneumophila. The reduction of intracellular iron availability by treatment with antibodies against transferrin receptor or with desferrioxamine suppressed the growth of L. pneumophila within BALB/c TG macrophages, suggesting that these cells do not restrict L. pneumophila growth because of iron. The production of nitric oxide was also similar in both macrophage populations, as measured by the Griess reaction. However, the synthesis of oxygen reactive species was three times higher in non-permissive BALB/c macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of host polyubiquitination by the ankb f-box protein of Legionella pneumophila.

“…The LCV proteome has also been generated using the Corby strain of L. pneumophila in the amoeba host Dictyostelium discoideum [73][74][75]. While the LCV proteome from RAW264.7 macrophages presents information on LCV biogenesis, RAW264.7 macrophages originate from the BALB/C mouse, whose primary macrophages are non-permissive to L. pneumophila infection [76,77]. The LCV proteome analysis from Dictyostelium discoideum contained 566 host proteins [73], while the LCV proteome from RAW264.7 macrophages contained 1156 proteins [74].…”