Effects of Sample Preparation on Chemistry, Cytotoxicity, and Inflammatory Responses Induced by Air Particulate Matter

Abstract

Methanol is used for high-efficiency extraction of air particulate (PM) mass from the sampling substrate in the high-volume cascade impactor. Sonication is needed during extraction and when dissolving dried PM samples in liquids used in exposure studies. We investigated the effects of these procedures on the PM chemistry and PM-induced cytotoxic and inflammatory responses in mouse macrophages. Untreated and methanol-treated ambient air reference PM samples (SRM1649a, EHC-93) and diesel PM (SRM1650) were tested after different sonication durations (530 min). Furthermore, the time dependency of the responses to SRM1649a, EHC-93, and a fine PM sample from Helsinki was investigated. Methanol pretreatment increased on average by 24% and 21% the recovery of water-soluble metals from SRM1649a and EHC-93, but not SRM1650. It had no systematic effect on the recoveries of inorganic secondary ions (NO3-, SO4(2-), NH4+) or the sum of genotoxic PAH compounds from the three reference samples. Nitric oxide (NO) response to SRM1650 was strongly enhanced by methanol pretreatment, whereas the cytotoxic or inflammatory responses to the ambient air PM samples (EHC-93, SRM1649a) were only slightly modified. Sonication duration was a modifying factor only in connection to SRM1650. Maximal interleukin (IL)-1 production was observed earlier (8 h) than maximal tumor necrosis factor (TNF) alpha and IL-6 productions (24 h), which indicates the importance to know the optimal time points for measurement of the selected response parameters. In conclusion, methanol extraction and reasonable sonication duration are not likely to modify the cytotoxic and inflammatory potency of ambient air PM samples, but some responses to air PM, rich in organic compounds, can be modified.

Switch regulation of interleukin-1 beta in downstream of inflammatory cytokines induced by two micro-sized silica particles on differentiated THP-1 macrophages

“…Currently, only a few studies have used more than two time points at a range of concentrations of particles (Mitschik et al, 2008). Jalava and his colleagues indicated that the markedly increased IL-1␤ production reached maximal level at 8 h or 12 h by RAW 264.7 macrophages after exposure to ambient air PM samples (Jalava et al, 2005), which is partly different from our results. Nevertheless, another study reported the secretion of IL-1␤ was highest at 6 h in THP-1 macrophages after exposure to particles in earlier durations of 0-6 h (Dostert et al, 2008), which support our present findings.…”

Using a pattern recognition approach to link inorganic chemical fingerprints of ambient PM2.5–0.1 with in vitro biological effects

“…Furthermore, it has been previously reported that methanol treatment can modify some biomarker responses to emission-source PM rich in organic compounds (Jalava et al 2005). The effects of methanol treatment on PM samples and on the chemistry, cytotoxicity, and inflammatory responses induced have been discussed in greater detail elsewhere (Jalava et al 2005). However, future studies should include the organic fraction in investigations that probe underlying mechanisms of PMrelated adverse health effects.…”

“…This aspect was not studied here because an organic solvent was used to extract PM from the filter substrate, which may have altered or removed some of the organic compounds. Furthermore, it has been previously reported that methanol treatment can modify some biomarker responses to emission-source PM rich in organic compounds (Jalava et al 2005). The effects of methanol treatment on PM samples and on the chemistry, cytotoxicity, and inflammatory responses induced have been discussed in greater detail elsewhere (Jalava et al 2005).…”

“…The effects of methanol sample preparation on the chemistry, cytotoxicity, and inflammatory responses induced by ambient PM have been previously reported and discussed (Jalava et al 2005). All particulates recovered from the same site during the same season were pooled together to give a homogeneous batch of particles representative of that site.…”

Characterization of Chemical and Microbial Species from Size-Segregated Indoor and Outdoor Particulate Samples

“…However, the samples in PM 1-2.5 and PM 0.2-1 size ranges were combined to form one pooled PM 0.2-2.5 sample to obtain a sufficient particulate mass for all analyses (chemical, microbial, toxicological). The size-segregated particulate samples were prepared for the chemical, microbial and toxicological analyses using previously validated procedures (Jalava et al, 2005(Jalava et al, , 2006. In brief, the sampled PUF-strips or PTFE filters were placed in 50-mL glass tubes and filled with methanol (J.T.…”