TY - JOUR

T1 - Evidence for the presence of air pollution nanoparticles in placental tissue cells

AU - Liu, N.M.

AU - Miyashita, L.

AU - Maher, B.A.

AU - McPhail, G.

AU - Jones, C.J.P.

AU - Barratt, B.

AU - Thangaratinam, S.

AU - Karloukovski, V.

AU - Ahmed, I.A.

AU - Aslam, Z.

AU - Grigg, J.

PY - 2021/1/10

Y1 - 2021/1/10

N2 - Inhaled particulate matter (PM) from combustion- and friction-sourced air pollution adversely affects organs distant from the lung. A putative mechanism for the remote effect of inhaled PM is that ultrafine, nano-sized fraction (<100 nm) translocates across the air-tissue barrier, directly interacting with phagocytic tissue cells. Although PM is reported in other tissues, whether it is phagocytosed by non-respiratory tissue resident cells is unclear. Using the placenta as an accessible organ for phagocytic cells, we sought to seek evidence for air pollution-derived PM in tissue resident phagocytes. Macrophage-enriched placental cells (MEPCs) were isolated, and examined by light and electron microscopy. MEPC carbon was assessed by image analysis (mean μm2/1000 cells); particle composition and numbers were investigated using magnetic analyses and energy dispersive X-ray spectroscopy. MEPCs phagocytic capacity was assessed by culture with diesel exhaust PM in vitro. Fifteen placentas were analysed. Black inclusions morphologically compatible with inhaled PM were identified within MEPCs from all samples (mean ± SEM carbon loading, 1000 MEPCs/participant of 0.004 ± 0.001 μm2). High resolution scanning/transmission electron microscopy revealed abundant nano-sized particle aggregates within MEPCs. MEPC PM was predominantly carbonaceous but also co-associated with a range of trace metals, indicative of high temperature (i.e. exogenous) generation. MEPCs contained readily-measurable amounts of iron-rich, ferrimagnetic particles, in concentrations/particle number concentrations ranging, respectively, from 8 to 50 ng/g and 10 to 60.107 magnetic particles/g (wet wt) MEPCs. Extracted MEPCs (n = 20/ placenta) were phagocytic for PM since all cells showed increased carbon area after culture with diesel PM in vitro (mean ± SEM increase 7.55 ± 1.26 μm2 carbon PM). These findings demonstrate that inhaled, metal-bearing, air pollution-derived PM can not only translocate to distant organs, but is taken up by tissue resident phagocytes in vivo. The human placenta, and hence probably the fetus, thus appears to be a target for such particles.

AB - Inhaled particulate matter (PM) from combustion- and friction-sourced air pollution adversely affects organs distant from the lung. A putative mechanism for the remote effect of inhaled PM is that ultrafine, nano-sized fraction (<100 nm) translocates across the air-tissue barrier, directly interacting with phagocytic tissue cells. Although PM is reported in other tissues, whether it is phagocytosed by non-respiratory tissue resident cells is unclear. Using the placenta as an accessible organ for phagocytic cells, we sought to seek evidence for air pollution-derived PM in tissue resident phagocytes. Macrophage-enriched placental cells (MEPCs) were isolated, and examined by light and electron microscopy. MEPC carbon was assessed by image analysis (mean μm2/1000 cells); particle composition and numbers were investigated using magnetic analyses and energy dispersive X-ray spectroscopy. MEPCs phagocytic capacity was assessed by culture with diesel exhaust PM in vitro. Fifteen placentas were analysed. Black inclusions morphologically compatible with inhaled PM were identified within MEPCs from all samples (mean ± SEM carbon loading, 1000 MEPCs/participant of 0.004 ± 0.001 μm2). High resolution scanning/transmission electron microscopy revealed abundant nano-sized particle aggregates within MEPCs. MEPC PM was predominantly carbonaceous but also co-associated with a range of trace metals, indicative of high temperature (i.e. exogenous) generation. MEPCs contained readily-measurable amounts of iron-rich, ferrimagnetic particles, in concentrations/particle number concentrations ranging, respectively, from 8 to 50 ng/g and 10 to 60.107 magnetic particles/g (wet wt) MEPCs. Extracted MEPCs (n = 20/ placenta) were phagocytic for PM since all cells showed increased carbon area after culture with diesel PM in vitro (mean ± SEM increase 7.55 ± 1.26 μm2 carbon PM). These findings demonstrate that inhaled, metal-bearing, air pollution-derived PM can not only translocate to distant organs, but is taken up by tissue resident phagocytes in vivo. The human placenta, and hence probably the fetus, thus appears to be a target for such particles.

KW - Air pollution, translocation of particulate matter

KW - Carbonaceous and metal-bearing PM

KW - Magnetite, macrophage

KW - Nanoparticles

KW - Phagocytosis

KW - Placenta

KW - Air pollution

KW - Carbon

KW - Cells

KW - Cytology

KW - Diesel engines

KW - Electron microscopes

KW - Energy dispersive spectroscopy

KW - Particle size

KW - Scanning electron microscopy

KW - Trace elements

KW - Energy dispersive X ray spectroscopy

KW - High resolution scanning

KW - Magnetic particle

KW - Nano-sized particles

KW - Number concentration

KW - Particle composition

KW - Particulate Matter

KW - Phagocytic capacity

KW - Tissue

KW - atmospheric pollution

KW - cell

KW - magnetite

KW - nanoparticle

KW - trace metal

U2 - 10.1016/j.scitotenv.2020.142235

DO - 10.1016/j.scitotenv.2020.142235

M3 - Journal article

VL - 751

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

M1 - 142235

ER -