2 research outputs found
In Vitro Exposures in Diesel Exhaust Atmospheres: Resuspension of PM from Filters versus Direct Deposition of PM from Air
One of the most widely used <i>in vitro</i> particulate
matter (PM) exposures methods is the collection of PM on filters,
followed by resuspension in a liquid medium, with subsequent addition
onto a cell culture. To avoid disruption of equilibria between gases
and PM, we have developed a direct <i>in vitro</i> sampling
and exposure method (DSEM) capable of PM-only exposures. We hypothesize
that the separation of phases and post-treatment of filter-collected
PM significantly modifies the toxicity of the PM compared to direct
deposition, resulting in a distorted view of the potential PM health
effects. Controlled test environments were created in a chamber that
combined diesel exhaust with an urban-like mixture. The complex mixture
was analyzed using both the DSEM and concurrently collected filter
samples. The DSEM showed that PM from test atmospheres produced significant
inflammatory response, while the resuspension exposures at the same
exposure concentration did not. Increasing the concentration of resuspended
PM sixteen times was required to yield measurable IL-8 expression.
Chemical analysis of the resuspended PM indicated a total absence
of carbonyl compounds compared to the test atmosphere during the direct-exposures.
Therefore, collection and resuspension of PM into liquid modifies
its toxicity and likely leads to underestimating toxicity
Gene Expression Profiling in Human Lung Cells Exposed to Isoprene-Derived Secondary Organic Aerosol
Secondary
organic aerosol (SOA) derived from the photochemical
oxidation of isoprene contributes a substantial mass fraction to atmospheric
fine particulate matter (PM<sub>2.5</sub>). The formation of isoprene
SOA is influenced largely by anthropogenic emissions through multiphase
chemistry of its multigenerational oxidation products. Considering
the abundance of isoprene SOA in the troposphere, understanding mechanisms
of adverse health effects through inhalation exposure is critical
to mitigating its potential impact on public health. In this study,
we assessed the effects of isoprene SOA on gene expression in human
airway epithelial cells (BEAS-2B) through an air–liquid interface
exposure. Gene expression profiling of 84 oxidative stress and 249
inflammation-associated human genes was performed. Our results show
that the expression levels of 29 genes were significantly altered
upon isoprene SOA exposure under noncytotoxic conditions (<i>p</i> < 0.05), with the majority (22/29) of genes passing
a false discovery rate threshold of 0.3. The most significantly affected
genes belong to the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)
transcription factor network. The Nrf2 function is confirmed through
a reporter cell line. Together with detailed characterization of SOA
constituents, this study reveals the impact of isoprene SOA exposure
on lung responses and highlights the importance of further understanding
its potential health outcomes