Cedars-Sinai study finds prolonged exposure to coarse PM in LA Basin air led to genetic changes in rat brains
Prolonged exposure to coarse particulate matter (PM2.5–10) in air pollution in the Los Angeles Basin triggered inflammation and the appearance of cancer-related genes in the brains of rats, a Cedars-Sinai study has found.
Previous research has documented the association between air pollution and a variety of diseases, including cancer. This study found markers indicating certain materials in coarse air pollution—nickel, in particular—may play a role in genetic changes related to disease development, said Julia Ljubimova, MD, PhD.
Ljubimova, director of the Nanomedicine Research Center at Cedars-Sinai, is the lead author of the open-access paper, published in Scientific Reports.
This study, which looked at novel data gathered in the Los Angeles area, has significant implications for the assessment of air quality in the region, particularly as people are exposed to air pollution here for decades.Dr. Ljubimova
For the study, sourced ambient PM from Riverside, California, and selectively exposed rats to coarse (PM2.5–10), fine (PM<2.5), or ultrafine particles (UFPM: <0.15 µm).
They characterized each PM type via atomic emission spectroscopy and detected nickel, cobalt and zinc within them. They 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 they 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.—Ljubimova et al.
The study found that coarse particulate matter in the region’s air pollution found its way into bodily systems in two ways: inhaled through the lungs, where trace metals and other materials enter the bloodstream and then the brain; and through the nose, where the materials are absorbed more directly into the brain.
Ljubimova noted that while the study’s findings may be unique to the composition of air pollution in the Los Angeles Basin, there are many examples of potentially damaging effects of air pollution exposures in major cities.
Our modern society is becoming increasingly urbanized and exposed to air pollution. This trend underscores the need for additional research on the biology of air-pollution-induced organ damage, along with a concerted effort aimed at reducing ambient air pollution levels.—Dr. Ljubimova
The study was supported by a grant from the BP/AQMD South Coast Air Quality Management District. Funding was provided by the Brain & Lung Tumor and Air Pollution Foundation that was established by the South Coast Air Quality Management District.
Julia Y. Ljubimova, Oliver Braubach, Rameshwar Patil, Antonella Chiechi, Jie Tang, Anna Galstyan, Ekaterina S. Shatalova, Michael T. Kleinman, Keith L. Black & Eggehard Holler (2018) “Coarse particulate matter (PM2.5–10) in Los Angeles Basin air induces expression of inflammation and cancer biomarkers in rat brains” Scientific Reports Volume 8, Article number: 5708 doi: 10.1038/s41598-018-23885-3