INTRODUCTION: Studies have correlated living close to major roads with Alzheimer's disease (AD) risk. However, the mechanisms responsible for this link remain unclear. METHODS: We exposed olfactory mucosa (OM) cells of healthy individuals and AD patients to diesel emissions (DE). Cytotoxicity of exposure was assessed, mRNA, miRNA expression, and DNA methylation analyses were performed. The discovered altered pathways were validated using data from the human population-based Rotterdam Study. RESULTS: DE exposure resulted in an almost four-fold higher response in AD OM cells, indicating increased susceptibility to DE effects. Methylation analysis detected different DNA methylation patterns, revealing new exposure targets. Findings were validated by analyzing data from the Rotterdam Study cohort and demonstrated a key role of nuclear factor erythroid 2-related factor 2 signaling in responses to air pollutants. DISCUSSION: This study identifies air pollution exposure biomarkers and pinpoints key pathways activated by exposure. The data suggest that AD individuals may face heightened risks due to impaired cellular defenses. HIGHLIGHTS: Healthy and AD olfactory cells respond differently to DE exposure. AD cells are highly susceptible to DE exposure. The NRF2 oxidative stress response is highly activated upon air pollution exposure. DE-exposed AD cells activate the unfolded protein response pathway. Key findings are also confirmed in a population-based study.

• Keywords
• Alzheimer's disease (AD), air pollution, air–liquid interface (ALI), heat shock protein (HSP), next‐generation sequencing (NGS), nuclear factor erythroid 2–related factor 2 (NRF2), traffic emissions, traffic‐related air pollution (TRAP) olfactory mucosa (OM),
• MeSH
• Alzheimer Disease * genetics   metabolism   MeSH
• Olfactory Mucosa metabolism   MeSH
• Epigenomics MeSH
• NF-E2-Related Factor 2 genetics   metabolism   MeSH
• Air Pollutants adverse effects   MeSH
• Middle Aged MeSH
• Humans MeSH
• DNA Methylation * MeSH
• MicroRNAs metabolism   genetics   MeSH
• Aged MeSH
• Gene Expression Profiling MeSH
• Transcriptome MeSH
• Vehicle Emissions * toxicity   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• NF-E2-Related Factor 2 MeSH
• Air Pollutants MeSH
• MicroRNAs MeSH
• NFE2L2 protein, human MeSH Browser
• Vehicle Emissions * MeSH

Gasoline engine emissions have been classified as possibly carcinogenic to humans and represent a significant health risk. In this study, we used MucilAir™, a three-dimensional (3D) model of the human airway, and BEAS-2B, cells originating from the human bronchial epithelium, grown at the air-liquid interface to assess the toxicity of ordinary gasoline exhaust produced by a direct injection spark ignition engine. The transepithelial electrical resistance (TEER), production of mucin, and lactate dehydrogenase (LDH) and adenylate kinase (AK) activities were analyzed after one day and five days of exposure. The induction of double-stranded DNA breaks was measured by the detection of histone H2AX phosphorylation. Next-generation sequencing was used to analyze the modulation of expression of the relevant 370 genes. The exposure to gasoline emissions affected the integrity, as well as LDH and AK leakage in the 3D model, particularly after longer exposure periods. Mucin production was mostly decreased with the exception of longer BEAS-2B treatment, for which a significant increase was detected. DNA damage was detected after five days of exposure in the 3D model, but not in BEAS-2B cells. The expression of CYP1A1 and GSTA3 was modulated in MucilAir™ tissues after 5 days of treatment. In BEAS-2B cells, the expression of 39 mRNAs was affected after short exposure, most of them were upregulated. The five days of exposure modulated the expression of 11 genes in this cell line. In conclusion, the ordinary gasoline emissions induced a toxic response in MucilAir™. In BEAS-2B cells, the biological response was less pronounced, mostly limited to gene expression changes.

• Keywords
• MucilAir™, air-liquid interface, bronchial epithelial cells, gasoline emissions, toxicity,
• MeSH
• Adenylate Kinase metabolism   MeSH
• Bronchi cytology   MeSH
• DNA Breaks, Double-Stranded MeSH
• Electric Impedance MeSH
• Epithelial Cells drug effects   metabolism   MeSH
• Cells, Cultured MeSH
• L-Lactate Dehydrogenase metabolism   MeSH
• Humans MeSH
• Mucins metabolism   MeSH
• Toxicity Tests methods   MeSH
• Transcriptome MeSH
• Vehicle Emissions toxicity   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Adenylate Kinase MeSH
• L-Lactate Dehydrogenase MeSH
• Mucins MeSH
• Vehicle Emissions MeSH