Effect of Concentrated Ambient Particles on Macrophage Phagocytosis and Killing of Streptococcus pneumoniae

Abstract

Particulate air pollution is linked to increased pneumonia epidemiologically and diminished lung bacterial clearance experimentally. We investigated the effect of concentrated ambient particles (CAPs, р PM 2.5 ) on the interaction of murine primary alveolar macrophages (AMs) and the murine macrophage cell line, J774 A.1, with Streptococcus pneumoniae. We found that CAPs increased binding of bacteria by both primary AMs and J774 cells (66.7 Ϯ 10.6% and 58.9 Ϯ 4.0%, respectively, n ϭ 4). In contrast to bacterial binding, CAPs decreased internalization in both AMs and J774 (55.4 Ϯ 8.5% and 54.7 Ϯ 5.1%, respectively, n ϭ 4). The rate of killing of internalized bacteria was similar, but CAPs caused a decrease in the absolute number of bacteria killed by macrophages, mainly due to decreased internalization. Additional analyses showed that soluble components of CAPs mediated the enhanced binding and decreased internalization of S. pneumoniae. Chelation of iron in soluble CAPs substantially reversed, while addition of iron as ferric ammonium citrate restored inhibition of phagocytosis of S. pneumoniae in vitro. The results identify phagocytic internalization as a specific target for toxic effects of air pollution particles on AMs.

Cytotoxicity and Characterization of Particles Collected From an Indium–Tin Oxide Production Facility

“…This may explain the caspase activation that was seen at 24 h postexposure in RAW cells ( Figure 7A). Macrophage dysfunction and toxicity from particle overload were observed in several previous studies, where cells preloaded with various particles can not perform their phagocytic duty (Lundborg et al, 2006;Zhou and Kobzik, 2007;Yang et al, 2001;Oberdorster, 1995) and succumb to toxicity from the engulfed particles (Allison et al, 1966;Hiura et al, 1999;Li et al, 2002).…”

Regulation of Aeroallergen Immunity by the Innate Immune System: Laboratory Evidence for a New Paradigm

“…However, in urban environments, diesel exhaust and other pollutants of human origin are likely to be found at far higher concentrations out of doors and these molecules are known to perturb immune homeostasis, at least in part, by creating oxidant stress, a phenomenon that is uniquely receptor independent [17] . Several laboratories have begun to investigate the immunostimulatory potential of unpurified samples of particulate matter (APM) prepared from outdoor air [32][33][34][35] . Moreover, Williams et al [32] have already published that APM has MyD88 independent immunostimulatory properties.…”

Dynamics of Increasing IFN-γ Exposure on Murine MH-S Cell-Line Alveolar Macrophage Phagocytosis ofStreptococcus pneumoniae

“…Overall phagocytic activity was measured as the ratio of the sum of both bound and internalized bacteria per macrophage using standard phagocytosis assays, as have been previously reported (Zhou and Kobzik 2007). Briefly, IFN-g exposed or unexposed MH-S cells were cultured with pneumococci at an MOI of 15 for 50 min at 37°C in 5% CO 2 .…”