Coarse particulate matter (PM2.5–10) in Los Angeles Basin air induces expression of inflammation and cancer biomarkers in rat brains

Abstract

Air pollution is linked to brain inflammation, which accelerates tumorigenesis and neurodegeneration. The molecular mechanisms that connect air pollution with brain pathology are largely unknown but seem to depend on the chemical composition of airborne particulate matter (PM). We sourced ambient PM from Riverside, California, and selectively exposed rats to coarse (PM2.5–10: 2.5–10 µm), fine (PM<2.5: <2.5 µm), or ultrafine particles (UFPM: <0.15 µm). We characterized each PM type via atomic emission spectroscopy and detected nickel, cobalt and zinc within them. We then exposed rats separately to each PM type for short (2 weeks), intermediate (1–3 months) and long durations (1 year). All three metals accumulated in rat brains during intermediate-length PM exposures. Via RNAseq analysis we then determined that intermediate-length PM2.5–10 exposures triggered the expression of the early growth response gene 2 (EGR2), genes encoding inflammatory cytokine pathways (IL13-Rα1 and IL-16) and the oncogene RAC1. Gene upregulation occurred only in brains of rats exposed to PM2.5–10 and correlated with cerebral nickel accumulation. We hypothesize that the expression of inflammation and oncogenesis-related genes is triggered by the combinatorial exposure to certain metals and toxins in Los Angeles Basin PM2.5–10.

Continuous Inhalation Exposure to Fungal Allergen Particulates Induces Lung Inflammation While Reducing Innate Immune Molecule Expression in the Brainstem

“…For much of the 20th century, the brain was viewed as immunologically separate from the rest of the body (reviewed in Carson et al., 2006 ; Perry, 2010 ; Czirr and Wyss-Coray, 2012; Cunningham, 2013 ). However, triggering acute or chronic systemic inflammation with viral, bacterial, and manmade toxicants is now well described to induce innate immune responses within the central nervous system (CNS) ( Perry, 2010 ; Cunningham, 2013 ; Calderón-Garcidueñas et al., 2016 ; Cole et al., 2016 ; Heusinkveld et al., 2016 ; Mumaw et al., 2016 ; Jayaraj et al., 2017 ; Bilbo et al., 2018 ; Ljubimova et al., 2018 ). Less studied are the neuroinflammatory consequences of airborne allergens ( Klein et al., 2016 ).…”

A semi-continuous study on the toxicity of atmospheric particles using a versatile aerosol concentration enrichment system (VACES): development and field characterization

“…(Jung et al, 2010;Freney et al, 2006;Pakbin et al, 2011;Zhao et al, 2005;Dameto et al, 2019). In addition, VACES has been applied to determine the relationship between particulate matter and health effects based on exposure experiments (Klocke et al, 2017;Ljubimova et al, 2018). Nevertheless, although VACES was originally developed to provide technical support for toxicity detection, there is no direct measurement data to show the change in toxicity between ambient particles and VACES particles.…”

Versatile aerosol concentration enrichment system (VACES) operating as a cloud condensation nuclei (CCN) concentrator: development and laboratory characterization

“…Increases in droplet number concentrations for the same water content can locally increase the albedo and the persistence of clouds (Abrecht, 1989). These are, respectively, termed the "Twomey" (first) and "cloud lifetime" (second) aerosol indirect effects (Twomey, 1977;Lohmann and Feichter, 2005;Charlson and Heintzenberg, 1995;IPCC, 2013). Cloud formation induced by the activation of atmospheric aerosols represents one of the main factors in determining the earth's radiative balance (Furutani et al, 2008) and consequently in estimating global climate change (IPCC, 2013;Houghton, 2001).…”

“…The VACES has been used in a number of human and animal toxicological studies of the adverse effects of exposure to particulate matter (e.g. Klocke et al, 2017;Ljubimova et al, 2018;Wang et al, 2018). The VACES has been also used to measure particulate matter in different locations, such as in an underground railway station (Loxham et al, 2013), in Mexico City (De Vizcaya-Ruiz et al, 2006), in California's San Joaquin valley (Plummer et al, 2012) and in the Netherlands (Steenhof et al, 2011).…”