Traffic-related ultrafine particles (UFPs) are an emerging health concern affecting the brain and increasing the risk of Alzheimer's disease (AD). PI3K/AKT signaling is known to contribute to neuronal survival and to be altered in AD. The nasal olfactory mucosa (OM) is a sensory tissue exposed directly to ambient air, and a starting point for olfactory neural circuits towards the brain. Evidence of air pollution-induced transcriptional regulation via microRNAs (miRNA) and DNA methylation (DNAmet) is accumulating and air pollutant-mediated disturbances in PI3K/AKT signaling have been reported. By utilizing a highly translational human-based in vitro model of OM, we aimed to investigate possible gene regulatory mechanisms in PI3K/AKT signaling induced by UFPs, and to compare the responses between cognitively healthy and individuals with AD. miRNA expression was analyzed using next-generation sequencing (NGS) and chip-based methylation analysis was performed to detect differentially methylated loci (DML). These data were combined with previously published transcriptomics analysis (mRNA) to construct an mRNA-miRNA-DNAmet-integrative network. Protein level changes were studied by immunoassays. We observed UFP-induced reductions in viability and increases in oxidative stress and DNA damage without eminent cell death. Integrative network analysis revealed multiple connections of miRNAs to differentially expressed genes in the PI3K/AKT pathway, and effects were most prominent in AD cells. Similarly, in AD cells DML were identified in transcription factor and apoptosis genes, downstream of PI3K/AKT signaling. Conclusively, traffic-related UFPs influence gene regulation of PI3K/AKT signaling to modulate OM cell survival, with existing AD pathology resulting in heightened vulnerability to UFP effects.
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.
- Klíčová slova
- 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
- Alzheimerova nemoc * genetika metabolismus MeSH
- čichová sliznice metabolismus MeSH
- epigenomika MeSH
- faktor 2 související s NF-E2 genetika metabolismus MeSH
- látky znečišťující vzduch škodlivé účinky MeSH
- lidé středního věku MeSH
- lidé MeSH
- metylace DNA * MeSH
- mikro RNA metabolismus genetika MeSH
- senioři MeSH
- stanovení celkové genové exprese MeSH
- transkriptom MeSH
- výfukové emise vozidel * toxicita MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- faktor 2 související s NF-E2 MeSH
- látky znečišťující vzduch MeSH
- mikro RNA MeSH
- NFE2L2 protein, human MeSH Prohlížeč
- výfukové emise vozidel * MeSH
Constituents of air pollution, the ultrafine particles (UFP) with a diameter of ≤0.1 μm, are considerably related to traffic emissions. Several studies link air pollution to Alzheimer's disease (AD), yet the exact relationship between the two remains poorly understood. Mitochondria are known targets of environmental toxicants, and their dysfunction is associated with neurodegenerative diseases. The olfactory mucosa (OM), located at the rooftop of the nasal cavity, is directly exposed to the environment and in contact with the brain. Mounting evidence suggests that the UFPs can impact the brain directly through the olfactory tract. By using primary human OM cultures established from nasal biopsies of cognitively healthy controls and individuals diagnosed with AD, we aimed to decipher the effects of traffic-related UFPs on mitochondria. The UFP samples were collected from the exhausts of a modern heavy-duty diesel engine (HDE) without aftertreatment systems, run with renewable diesel (A0) and petroleum diesel (A20), and from an engine of a 2019 model diesel passenger car (DI-E6d) equipped with state-of-the-art aftertreatment devices and run with renewable diesel (Euro6). OM cells were exposed to three different UFPs for 24-h and 72-h, after which cellular processes were assessed on the functional and transcriptomic levels. Our results show that UFPs impair mitochondrial functions in primary human OM cells by hampering oxidative phosphorylation (OXPHOS) and redox balance, and the responses of AD cells differ from cognitively healthy controls. RNA-Seq and IPA® revealed inhibition of OXPHOS and mitochondrial dysfunction in response to UFPs A0 and A20. Functional validation confirmed that A0 and A20 impair cellular respiration, decrease ATP levels, and disturb redox balance by altering NAD and glutathione metabolism, leading to increased ROS and oxidative stress. RNA-Seq and functional assessment revealed the presence of AD-related alterations in human OM cells and that different fuels and engine technologies elicit differential effects.
- Klíčová slova
- Mitochondrial dysfunction, Olfactory mucosa (OM), Oxidative phosphorylation (OXPHOS), RNA sequencing (RNA-Seq), Redox balance, Ultrafine particles (UFP),
- MeSH
- Alzheimerova nemoc * metabolismus etiologie patologie chemicky indukované MeSH
- čichová sliznice * metabolismus patologie účinky léků MeSH
- látky znečišťující vzduch toxicita škodlivé účinky MeSH
- lidé MeSH
- mitochondrie * metabolismus účinky léků MeSH
- oxidační stres účinky léků MeSH
- pevné částice * škodlivé účinky toxicita MeSH
- reaktivní formy kyslíku metabolismus MeSH
- senioři MeSH
- výfukové emise vozidel toxicita MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- látky znečišťující vzduch MeSH
- pevné částice * MeSH
- reaktivní formy kyslíku MeSH
- výfukové emise vozidel MeSH
Ultrafine particles (UFP) with a diameter of ≤0.1 μm, are contributors to ambient air pollution and derived mainly from traffic emissions, yet their health effects remain poorly characterized. The olfactory mucosa (OM) is located at the rooftop of the nasal cavity and directly exposed to both the environment and the brain. Mounting evidence suggests that pollutant particles affect the brain through the olfactory tract, however, the exact cellular mechanisms of how the OM responds to air pollutants remain poorly known. Here we show that the responses of primary human OM cells are altered upon exposure to UFPs and that different fuels and engines elicit different adverse effects. We used UFPs collected from exhausts of a heavy-duty-engine run with renewable diesel (A0) and fossil diesel (A20), and from a modern diesel vehicle run with renewable diesel (Euro6) and compared their health effects on the OM cells by assessing cellular processes on the functional and transcriptomic levels. Quantification revealed all samples as UFPs with the majority of particles being ≤0.1 μm by an aerodynamic diameter. Exposure to A0 and A20 induced substantial alterations in processes associated with inflammatory response, xenobiotic metabolism, olfactory signaling, and epithelial integrity. Euro6 caused only negligible changes, demonstrating the efficacy of aftertreatment devices. Furthermore, when compared to A20, A0 elicited less pronounced effects on OM cells, suggesting renewable diesel induces less adverse effects in OM cells. Prior studies and these results suggest that PAHs may disturb the inflammatory process and xenobiotic metabolism in the OM and that UFPs might mediate harmful effects on the brain through the olfactory route. This study provides important information on the adverse effects of UFPs in a human-based in vitro model, therefore providing new insight to form the basis for mitigation and preventive actions against the possible toxicological impairments caused by UFP exposure.
- Klíčová slova
- Air pollution, RNA-Seq, Traffic emissions, Ultrafine particles (UFP),
- MeSH
- čichová sliznice chemie MeSH
- látky znečišťující vzduch * toxicita analýza MeSH
- lidé MeSH
- pevné částice toxicita analýza MeSH
- výfukové emise vozidel toxicita analýza MeSH
- xenobiotika * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- látky znečišťující vzduch * MeSH
- pevné částice MeSH
- výfukové emise vozidel MeSH
- xenobiotika * MeSH
This study evaluated how exposure to the ubiquitous air pollution component, ultrafine particles (UFPs), alters the olfactory bulb (OB) transcriptome. The study utilised a whole-body inhalation chamber to simulate real-life conditions and focused on UFPs due to their high translocation and deposition ability in OBs as well as their prevalence in ambient air. Female C57BL/6J mice were exposed to clean air or to freshly generated combustion derived UFPs for two weeks, after which OBs were dissected and mRNA transcripts were investigated using RNA sequencing analysis. For the first time, transcriptomics was applied to determine changes in mRNA expression levels occurring after subacute exposure to UFPs in the OBs. We found forty-five newly described mRNAs to be involved in air pollution-induced responses, including genes involved in odorant binding, synaptic regulation, and myelination signalling pathway, providing new gene candidates for future research. This study provides new insights for the environmental science and neuroscience fields and nominates future research directions.
- Klíčová slova
- Air pollution, Brain, Myelin protein zero (Mpz), Odorant-binding protein (OBP), Olfactory bulb, Ultrafine particles (UFP),
- MeSH
- biologické markery metabolismus MeSH
- bulbus olfactorius chemie metabolismus MeSH
- látky znečišťující vzduch * toxicita analýza MeSH
- messenger RNA metabolismus MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- pevné částice toxicita analýza MeSH
- stanovení celkové genové exprese MeSH
- transkriptom MeSH
- velikost částic MeSH
- znečištění ovzduší * analýza MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- biologické markery MeSH
- látky znečišťující vzduch * MeSH
- messenger RNA MeSH
- pevné částice MeSH
Hypoxia induces changes in the secretion of extracellular vesicles (EVs) in several non-neuronal cells and pathological conditions. EVs are packed with biomolecules, such as microRNA(miR)-21-5p, which respond to hypoxia. However, the true EV association of miR-21-5p, and its functional or biomarker relevance, are inadequately characterised. Neurons are extremely sensitive cells, and it is not known whether the secretion of neuronal EVs and miR-21-5p are altered upon hypoxia. Here, we characterised the temporal EV secretion profile and cell viability of neurons under hypoxia. Hypoxia induced a rapid increase of miR-21a-5p secretion in the EVs, which preceded the elevation of hypoxia-induced tissue or cellular miR-21a-5p. Prolonged hypoxia induced cell death and the release of morphologically distinct EVs. The EVs protected miR-21a-5p from enzymatic degradation but a remarkable fraction of miR-21a-5p remained fragile and non-EV associated. The increase in miR-21a-5p secretion may have biomarker potential, as high blood levels of miR-21-5p in stroke patients were associated with significant disability at hospital discharge. Our data provides an understanding of the dynamic regulation of EV secretion from neurons under hypoxia and provides a candidate for the prediction of recovery from ischemic stroke.
- Klíčová slova
- biomarkers, extracellular vesicle, hypoxia, ischemic stroke, miR-21a-5p, neuron,
- MeSH
- biologické markery metabolismus MeSH
- extracelulární vezikuly * metabolismus MeSH
- lidé MeSH
- mikro RNA * metabolismus MeSH
- neurony metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- biologické markery MeSH
- mikro RNA * MeSH
Neuroinflammation is an important feature in the pathogenesis and progression of central nervous system (CNS) diseases including Alzheimer's disease (AD). One of the widely used animal models of peripherally induced neuroinflammation and neurodegeneration is a lipopolysaccharide (LPS)-induced inflammation mouse model. An acute LPS administration has been widely used for investigation of inflammation-associated disease and testing inflammation-targeting drug candidates. In the present metabolomic, lipidomic and proteomic study, we investigated short-term effects of systemic inflammation induced by LPS administration on the mouse plasma and brain cortical and hippocampal metabolome, lipidome as well as expression of the brain cortical proteins which were shown to be involved in inflammation-associated CNS diseases. From a global perspective, the hippocampus was more vulnerable to the effects of LPS-induced systemic inflammation than the cortex. In addition, the study revealed several brain region-specific changes in metabolic pathways and lipids, such as statistically significant increase in several cortical and hippocampal phosphatidylcholines/phosphatidylethanolamines, and significantly decreased levels of brain cortical betaine after LPS treatment in mice. Moreover, LPS treatment in mice caused significantly increased protein expression of GluN1 receptor in the brain cortex. The revealed perturbations in the LPS-induced inflammation mouse model may give insight into the mechanisms underlying inflammation-associated CNS diseases. In addition, the finding of the study provide important information about the appropriate use of the model during target validation and drug candidate testing.
- Klíčová slova
- Alzheimer’s disease, lipidomics, lipopolysaccharide, metabolomics, proteomics,
- MeSH
- lipidomika * MeSH
- lipopolysacharidy * MeSH
- modely nemocí na zvířatech MeSH
- myši MeSH
- proteomika MeSH
- zánět metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- lipopolysacharidy * MeSH
The adverse effects of air pollutants on the respiratory and cardiovascular systems are unquestionable. However, in recent years, indications of effects beyond these organ systems have become more evident. Traffic-related air pollution has been linked with neurological diseases, exacerbated cognitive dysfunction, and Alzheimer's disease. However, the exact air pollutant compositions and exposure scenarios leading to these adverse health effects are not known. Although several components of air pollution may be at play, recent experimental studies point to a key role of ultrafine particles (UFPs). While the importance of UFPs has been recognized, almost nothing is known about the smallest fraction of UFPs, and only >23 nm emissions are regulated in the EU. Moreover, the role of the semivolatile fraction of the emissions has been neglected. The Transport-Derived Ultrafines and the Brain Effects (TUBE) project will increase knowledge on harmful ultrafine air pollutants, as well as semivolatile compounds related to adverse health effects. By including all the major current combustion and emission control technologies, the TUBE project aims to provide new information on the adverse health effects of current traffic, as well as information for decision makers to develop more effective emission legislation. Most importantly, the TUBE project will include adverse health effects beyond the respiratory system; TUBE will assess how air pollution affects the brain and how air pollution particles might be removed from the brain. The purpose of this report is to describe the TUBE project, its background, and its goals.
- Klíčová slova
- CNS, UFP, air pollution, brain, particulate matter, toxicology, traffic,
- MeSH
- látky znečišťující vzduch * analýza toxicita MeSH
- mozek MeSH
- pevné částice analýza toxicita MeSH
- velikost částic MeSH
- znečištění ovzduší * analýza statistika a číselné údaje MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- látky znečišťující vzduch * MeSH
- pevné částice MeSH
Peripheral infections followed by systemic inflammation may contribute to the onset of Alzheimer`s disease (AD) and accelerate the disease progression later in life. Yet, the impact of systemic inflammation on the plasma and brain tissue metabolome and lipidome in AD has not been investigated. In this study, targeted metabolomic and untargeted lipidomic profiling experiments were performed on the plasma, cortices, and hippocampi of wild-type (WT) mice and transgenic APdE9 mice after chronic lipopolysaccharide (LPS) treatment, as well as saline-treated APdE9 mice. The lipidome and the metabolome of these mice were compared to saline-treated WT animals. In the brain tissue of all three models, the lipidome was more influenced than the metabolome. The LPS-treated APdE9 mice had the highest number of changes in brain metabolic pathways with significant alterations in levels of lysine, myo-inositol, spermine, phosphocreatine, acylcarnitines and diacylglycerols, which were not observed in the saline-treated APdE9 mice. In the WT mice, the effect of the LPS administration on metabolome and lipidome was negligible. The study provided exciting information about the biochemical perturbations due to LPS-induced inflammation in the transgenic AD model, which can significantly enhance our understanding of the role of systemic inflammation in AD pathogenesis.
- MeSH
- Alzheimerova nemoc metabolismus MeSH
- amyloidní beta-protein metabolismus MeSH
- amyloidový prekurzorový protein beta genetika imunologie metabolismus MeSH
- hipokampus metabolismus MeSH
- lipidomika metody MeSH
- metabolom MeSH
- metabolomika metody MeSH
- modely nemocí na zvířatech MeSH
- mozek metabolismus MeSH
- myši inbrední C57BL MeSH
- myši transgenní MeSH
- myši MeSH
- presenilin-1 metabolismus MeSH
- zánět metabolismus MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- amyloidní beta-protein MeSH
- amyloidový prekurzorový protein beta MeSH
- presenilin-1 MeSH
