Aging Exacerbates Neuroinflammatory Outcomes Induced by Acute Ozone Exposure

Multi-omics analysis reveals the dynamic interplay between Vero host chromatin structure and function during vaccinia virus infection

The genome folds into complex configurations and structures thought to profoundly impact its function. The intricacies of this dynamic structure-function relationship are not well understood particularly in the context of viral infection. To unravel this interplay, here we provide a comprehensive investigation of simultaneous host chromatin structural (via Hi-C and ATAC-seq) and functional changes (via RNA-seq) in response to vaccinia virus infection. Over time, infection significantly impacts global and local chromatin structure by increasing long-range intra-chromosomal interactions and B compartmentalization and by decreasing chromatin accessibility and inter-chromosomal interactions. Local accessibility changes are independent of broad-scale chromatin compartment exchange (~12% of the genome), underscoring potential independent mechanisms for global and local chromatin reorganization. While infection structurally condenses the host genome, there is nearly equal bidirectional differential gene expression. Despite global weakening of intra-TAD interactions, functional changes including downregulated immunity genes are associated with alterations in local accessibility and loop domain restructuring. Therefore, chromatin accessibility and local structure profiling provide impactful predictions for host responses and may improve development of efficacious anti-viral counter measures including the optimization of vaccine design.

Association of Gaseous Ambient Air Pollution and Dementia-Related Neuroimaging Markers in the ARIC Cohort, Comparing Exposure Estimation Methods and Confounding by Study Site

BACKGROUND

Evidence linking gaseous air pollution to late-life brain health is mixed.

OBJECTIVE

We explored associations between exposure to gaseous pollutants and brain magnetic resonance imaging (MRI) markers among Atherosclerosis Risk in Communities (ARIC) Study participants, with attention to the influence of exposure estimation method and confounding by site.

METHODS

We considered data from 1,665 eligible ARIC participants recruited from four US sites in the period 1987-1989 with valid brain MRI data from Visit 5 (2011-2013). We estimated 10-y (2001-2010) mean carbon monoxide (CO), nitrogen dioxide (NO 2 ), nitrogen oxides (NO x ), and 8- and 24-h ozone (O 3 ) concentrations at participant addresses, using multiple exposure estimation methods. We estimated site-specific associations between pollutant exposures and brain MRI outcomes (total and regional volumes; presence of microhemorrhages, infarcts, lacunes, and severe white matter hyperintensities), using adjusted linear and logistic regression models. We compared meta-analytically combined site-specific associations to analyses that did not account for site.

RESULTS

Within-site exposure distributions varied across exposure estimation methods. Meta-analytic associations were generally not statistically significant regardless of exposure, outcome, or exposure estimation method; point estimates often suggested associations between higher NO 2   and   NO x and smaller temporal lobe, deep gray, hippocampal, frontal lobe, and Alzheimer disease signature region of interest volumes and between higher CO and smaller temporal and frontal lobe volumes. Analyses that did not account for study site more often yielded significant associations and sometimes different direction of associations.

DISCUSSION

Patterns of local variation in estimated air pollution concentrations differ by estimation method. Although we did not find strong evidence supporting impact of gaseous pollutants on brain changes detectable by MRI, point estimates suggested associations between higher exposure to CO, NO x , and NO 2 and smaller regional brain volumes. Analyses of air pollution and dementia-related outcomes that do not adjust for location likely underestimate uncertainty and may be susceptible to confounding bias. https://doi.org/10.1289/EHP13906.

Peripheral HMGB1 is linked to O3 pathology of disease-associated astrocytes and amyloid

INTRODUCTION

Ozone (O3) is an air pollutant associated with Alzheimer's disease (AD) risk. The lung-brain axis is implicated in O3-associated glial and amyloid pathobiology; however, the role of disease-associated astrocytes (DAAs) in this process remains unknown.

METHODS

The O3-induced astrocyte phenotype was characterized in 5xFAD mice by spatial transcriptomics and proteomics. Hmgb1fl/fl LysM-Cre+ mice were used to assess the role of peripheral myeloid cell high mobility group box 1 (HMGB1).

RESULTS

O3 increased astrocyte and plaque numbers, impeded the astrocyte proteomic response to plaque deposition, augmented the DAA transcriptional fingerprint, increased astrocyte-microglia contact, and reduced bronchoalveolar lavage immune cell HMGB1 expression in 5xFAD mice. O3-exposed Hmgb1fl/fl LysM-Cre+ mice exhibited dysregulated DAA mRNA markers.

DISCUSSION

Astrocytes and peripheral myeloid cells are critical lung-brain axis interactors. HMGB1 loss in peripheral myeloid cells regulates the O3-induced DAA phenotype. These findings demonstrate a mechanism and potential intervention target for air pollution-induced AD pathobiology.

HIGHLIGHTS

Astrocytes are part of the lung-brain axis, regulating how air pollution affects plaque pathology. Ozone (O3) astrocyte effects are associated with increased plaques and modified by plaque localization. O3 uniquely disrupts the astrocyte transcriptomic and proteomic disease-associated astrocyte (DAA) phenotype in plaque associated astrocytes (PAA). O3 changes the PAA cell contact with microglia and cell-cell communication gene expression. Peripheral myeloid cell high mobility group box 1 regulates O3-induced transcriptomic changes in the DAA phenotype.

Ozone-induced neurotoxicity: In vitro and in vivo evidence

Together with cities in higher-income nations, it is anticipated that the real global ozone is rising in densely populated areas of Asia and Africa. This review aims to discuss the possible neurotoxic pollutants and ozone-induced neurotoxicity: in vitro and in vivo, along with possible biomarkers to assess ozone-related oxidative stress. As a methodical and scientific strategy for hazard identification and risk characterization of human chemical exposures, toxicological risk assessment is increasingly being implemented. While traditional methods are followed by in vitro toxicology, cell culture techniques are being investigated in modern toxicology. In both human and rodent models, aging makes the olfactory circuitry vulnerable to spreading immunological responses from the periphery to the brain because it lacks the blood-brain barrier. The ozone toxicity is elusive as it shows ventral and dorsal root injury cases even in the milder dose. Its potential toxicity should be disclosed to understand further the clear mechanism insights of how it acts in cellular aspects. Human epidemiological research has confirmed the conclusions that prenatal and postnatal exposure to high levels of air pollution are linked to behavioral alterations in offspring. O3 also enhances blood circulation. It has antibacterial action, which may have an impact on the gut microbiota. It also activates immunological, anti-inflammatory, proteasome, and growth factor signaling Prolonged O3 exposure causes oxidative damage to plasma proteins and lipids and damages the structural and functional integrity of the mitochondria. Finally, various studies need to be conducted to identify the potential biomarkers associated with ozone and the brain.

Aging, longevity, and the role of environmental stressors: a focus on wildfire smoke and air quality

Aging is a complex biological process involving multiple interacting mechanisms and is being increasingly linked to environmental exposures such as wildfire smoke. In this review, we detail the hallmarks of aging, emphasizing the role of telomere attrition, cellular senescence, epigenetic alterations, proteostasis, genomic instability, and mitochondrial dysfunction, while also exploring integrative hallmarks - altered intercellular communication and stem cell exhaustion. Within each hallmark of aging, our review explores how environmental disasters like wildfires, and their resultant inhaled toxicants, interact with these aging mechanisms. The intersection between aging and environmental exposures, especially high-concentration insults from wildfires, remains under-studied. Preliminary evidence, from our group and others, suggests that inhaled wildfire smoke can accelerate markers of neurological aging and reduce learning capabilities. This is likely mediated by the augmentation of circulatory factors that compromise vascular and blood-brain barrier integrity, induce chronic neuroinflammation, and promote age-associated proteinopathy-related outcomes. Moreover, wildfire smoke may induce a reduced metabolic, senescent cellular phenotype. Future interventions could potentially leverage combined anti-inflammatory and NAD + boosting compounds to counter these effects. This review underscores the critical need to study the intricate interplay between environmental factors and the biological mechanisms of aging to pave the way for effective interventions.

Application of mesenchymal stem cells for anti-senescence and clinical challenges

Senescence is a hot topic nowadays, which shows the accumulation of senescent cells and inflammatory factors, leading to the occurrence of various senescence-related diseases. Although some methods have been identified to partly delay senescence, such as strengthening exercise, restricting diet, and some drugs, these only slow down the process of senescence and cannot fundamentally delay or even reverse senescence. Stem cell-based therapy is expected to be a potential effective way to alleviate or cure senescence-related disorders in the coming future. Mesenchymal stromal cells (MSCs) are the most widely used cell type in treating various diseases due to their potentials of self-replication and multidirectional differentiation, paracrine action, and immunoregulatory effects. Some biological characteristics of MSCs can be well targeted at the pathological features of aging. Therefore, MSC-based therapy is also a promising strategy to combat senescence-related diseases. Here we review the recent progresses of MSC-based therapies in the research of age-related diseases and the challenges in clinical application, proving further insight and reference for broad application prospects of MSCs in effectively combating senesce in the future.

Biomass smoke inhalation promotes neuroinflammatory and metabolomic temporal changes in the hippocampus of female mice

Smoke from wildland fires has been shown to produce neuroinflammation in preclinical models, characterized by neural infiltrations of neutrophils and monocytes, as well as altered neurovascular endothelial phenotypes. To address the longevity of such outcomes, the present study examined the temporal dynamics of neuroinflammation and metabolomics after inhalation exposures from biomass-derived smoke. 2-month-old female C57BL/6 J mice were exposed to wood smoke every other day for 2 weeks at an average exposure concentration of 0.5 mg/m3. Subsequent serial euthanasia occurred at 1-, 3-, 7-, 14-, and 28-day post-exposure. Flow cytometry of right hemispheres revealed two endothelial populations of CD31Hi and CD31Med expressors, with wood smoke inhalation causing an increased proportion of CD31Hi. These populations of CD31Hi and CD31Med were associated with an anti-inflammatory and pro-inflammatory response, respectively, and their inflammatory profiles were largely resolved by the 28-day mark. However, activated microglial populations (CD11b+/CD45low) remained higher in wood smoke-exposed mice than controls at day 28. Infiltrating neutrophil populations decreased to levels below controls by day 28. However, the MHC-II expression of the peripheral immune infiltrate remained high, and the population of neutrophils retained an increased expression of CD45, Ly6C, and MHC-II. Utilizing an unbiased approach examining the metabolomic alterations, we observed notable hippocampal perturbations in neurotransmitter and signaling molecules, such as glutamate, quinolinic acid, and 5-α-dihydroprogesterone. Utilizing a targeted panel designed to explore the aging-associated NAD+ metabolic pathway, wood smoke exposure drove fluctuations and compensations across the 28-day time course, ending with decreased hippocampal NAD+ abundance on day 28. Summarily, these results indicate a highly dynamic neuroinflammatory environment, with potential resolution extending past 28 days, the implications of which may include long-term behavioral changes, systemic and neurological sequalae directly associated with wildfire smoke exposure.

Sex-specific effects in how childhood exposures to multiple ambient air pollutants affect white matter microstructure development across early adolescence

Ambient air pollution is ubiquitous, yet questions remain as to how it might impact the developing brain. Large changes occur in the brain's white matter (WM) microstructure across adolescence, with noticeable differences in WM integrity in male and female youth. Here we report sex-stratified effects of fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) on longitudinal patterns of WM microstructure from 9-13 years-old in 8,182 (49% female) participants using restriction spectrum imaging. After adjusting for key sociodemographic factors, multi-pollutant, sex-stratified models showed that one-year annual exposure to PM2.5 and NO2 was associated with higher, while O3 was associated with lower, intracellular diffusion at age 9. All three pollutants also affected trajectories of WM maturation from 9-13 years-old, with some sex-specific differences in the number and anatomical locations of tracts showing altered trajectories of intracellular diffusion. Concentrations were well-below current U.S. standards, suggesting exposure to these criteria pollutants during adolescence may have long-term consequences on brain development.

Neuroinflammatory and Metabolomic Temporal Dynamics Following Wood Smoke Inhalation

Smoke from wildland fires has been shown to produce neuroinflammation in preclinical models, characterized by neural infiltrations of neutrophils and monocytes, as well as altered neurovascular endothelial phenotypes. To address the longevity of such outcomes, the present study examined the neuroinflammatory and metabolomic temporal dynamics after inhalation exposures from biomass-derived smoke. 2-month-old female C57BL/6J mice were exposed to wood smoke every other day for two weeks at an average exposure concentration of 0.5mg/m 3 . Subsequent serial euthanasia occurred at 1-, 3-, 7-, 14-, and 28-days post-exposure. Flow cytometry of right hemispheres revealed two endothelial populations of PECAM (CD31), high and medium expressors, with wood smoke inhalation causing an increased proportion of PECAM Hi . These populations of PECAM Hi and PECAM Med were associated with an anti-inflammatory and pro-inflammatory response, respectively, and their inflammatory profiles were largely resolved by the 28-day mark. However, activated microglial populations (CD11b + /CD45 low ) remained higher in wood smoke-exposed mice than controls at day 28. Infiltrating neutrophil populations decreased to levels below controls by day 28. However, the MHC-II expression of the peripheral immune infiltrate remained high, and the population of neutrophils retained an increased expression of CD45, Ly6C, and MHC-II. Utilizing an unbiased approach examining the metabolomic alterations, we observed notable hippocampal perturbations in neurotransmitter and signaling molecules like glutamate, quinolinic acid, and 5-α-dihydroprogesterone. Utilizing a targeted panel designed to explore the aging-associated NAD + metabolic pathway, wood smoke exposure drove fluctuations and compensations across the 28-day time course, ending with decreased hippocampal NAD + abundance at day 28. Summarily, these results indicate a highly dynamic neuroinflammatory environment, with potential resolution extending past 28 days, the implications of which may include long-term behavioral changes, systemic and neurological sequalae directly associated wtith wildfire smoke exposure.

Aging influence on pulmonary and systemic inflammation and neural metabolomics arising from pulmonary multi-walled carbon nanotube exposure in apolipoprotein E-deficient and C57BL/6 female mice

OBJECTIVE

Environmental exposures exacerbate age-related pathologies, such as cardiovascular and neurodegenerative diseases. Nanoparticulates, and specifically carbon nanomaterials, are a fast-growing contributor to the category of inhalable pollutants, whose risks to health are only now being unraveled. The current study assessed the exacerbating effect of age on multiwalled-carbon nanotube (MWCNT) exposure in young and old C57BL/6 and ApoE-/- mice.

MATERIALS AND METHODS

Female C57BL/6 and apolipoprotein E-deficient (ApoE-/-) mice, aged 8 weeks and 15 months, were exposed to 0 or 40 µg MWCNT via oropharyngeal aspiration. Pulmonary inflammation, inflammatory bioactivity of serum, and neurometabolic changes were assessed at 24 h post-exposure.

RESULTS

Pulmonary neutrophil infiltration was induced by MWCNT in bronchoalveolar lavage fluid in both C57BL/6 and ApoE-/-. Macrophage counts decreased with MWCNT exposure in ApoE-/- mice but were unaffected by exposure in C57BL/6 mice. Older mice appeared to have greater MWCNT-induced total protein in lavage fluid. BALF cytokines and chemokines were elevated with MWCNT exposure, but CCL2, CXCL1, and CXCL10 showed reduced responses to MWCNT in older mice. However, no significant serum inflammatory bioactivity was detected. Cerebellar metabolic changes in response to MWCNT were modest, but age and strain significantly influenced metabolite profiles assessed. ApoE-/- mice and older mice exhibited less robust metabolite changes in response to exposure, suggesting a reduced health reserve.

CONCLUSIONS

Age influences the pulmonary and neurological responses to short-term MWCNT exposure. However, with only the model of moderate aging (15 months) in this study, the responses appeared modest compared to inhaled toxicant impacts in more advanced aging models.

The bidirectional lung brain-axis of amyloid-β pathology: ozone dysregulates the peri-plaque microenvironment

The mechanisms underlying how urban air pollution affects Alzheimer's disease (AD) are largely unknown. Ozone (O3) is a reactive gas component of air pollution linked to increased AD risk, but is confined to the respiratory tract after inhalation, implicating the peripheral immune response to air pollution in AD neuropathology. Here, we demonstrate that O3 exposure impaired the ability of microglia, the brain's parenchymal immune cells, to associate with and form a protective barrier around Aβ plaques, leading to augmented dystrophic neurites and increased Aβ plaque load. Spatial proteomic profiling analysis of peri-plaque proteins revealed a microenvironment-specific signature of dysregulated disease-associated microglia protein expression and increased pathogenic molecule levels with O3 exposure. Unexpectedly, 5xFAD mice exhibited an augmented pulmonary cell and humoral immune response to O3, supporting that ongoing neuropathology may regulate the peripheral O3 response. Circulating HMGB1 was one factor upregulated in only 5xFAD mice, and peripheral HMGB1 was separately shown to regulate brain Trem2 mRNA expression. These findings demonstrate a bidirectional lung-brain axis regulating the central and peripheral AD immune response and highlight this interaction as a potential novel therapeutic target in AD.

Effects of Ozone on Sickness and Depressive-like Behavioral and Biochemical Phenotypes and Their Regulation by Serum Amyloid A in Mice

Ozone (O₃) is an air pollutant that primarily damages the lungs, but growing evidence supports the idea that O₃ also harms the brain; acute exposure to O₃ has been linked to central nervous system (CNS) symptoms such as depressed mood and sickness behaviors. However, the mechanisms by which O₃ inhalation causes neurobehavioral changes are limited. One hypothesis is that factors in the circulation bridge communication between the lungs and brain following O₃ exposure. In this study, our goals were to characterize neurobehavioral endpoints of O₃ exposure as they relate to markers of systemic and pulmonary inflammation, with a particular focus on serum amyloid A (SAA) and kynurenine as candidate mediators of O₃ behavioral effects. We evaluated O₃-induced dose-, time- and sex-dependent changes in pulmonary inflammation, circulating SAA and kynurenine and its metabolic enzymes, and sickness and depressive-like behaviors in Balb/c and CD-1 mice. We found that 3 parts per million (ppm) O₃, but not 2 or 1 ppm O₃, increased circulating SAA and lung inflammation, which were resolved by 48 h and was worse in females. We also found that indoleamine 2,3-dioxygenase (Ido1) mRNA expression was increased in the brain and spleen 24 h after 3 ppm O₃ and that kynurenine was increased in blood. Sickness and depressive-like behaviors were observed at all O₃ doses (1-3 ppm), suggesting that behavioral responses to O₃ can occur independently of increased SAA or neutrophils in the lungs. Using SAA knockout mice, we found that SAA did not contribute to O₃-induced pulmonary damage or inflammation, systemic increases in kynurenine post-O₃, or depressive-like behavior but did contribute to weight loss. Together, these findings indicate that acute O₃ exposure induces transient symptoms of sickness and depressive-like behaviors that may occur in the presence or absence of overt pulmonary neutrophilia and systemic increases of SAA. SAA does not appear to contribute to pulmonary inflammation induced by O₃, although it may contribute to other aspects of sickness behavior, as reflected by a modest effect on weight loss.

Current practice and recommendations for advancing how human variability and susceptibility are considered in chemical risk assessment

A key element of risk assessment is accounting for the full range of variability in response to environmental exposures. Default dose-response methods typically assume a 10-fold difference in response to chemical exposures between average (healthy) and susceptible humans, despite evidence of wider variability. Experts and authoritative bodies support using advanced techniques to better account for human variability due to factors such as in utero or early life exposure and exposure to multiple environmental, social, and economic stressors.This review describes: 1) sources of human variability and susceptibility in dose-response assessment, 2) existing US frameworks for addressing response variability in risk assessment; 3) key scientific inadequacies necessitating updated methods; 4) improved approaches and opportunities for better use of science; and 5) specific and quantitative recommendations to address evidence and policy needs.Current default adjustment factors do not sufficiently capture human variability in dose-response and thus are inadequate to protect the entire population. Susceptible groups are not appropriately protected under current regulatory guidelines. Emerging tools and data sources that better account for human variability and susceptibility include probabilistic methods, genetically diverse in vivo and in vitro models, and the use of human data to capture underlying risk and/or assess combined effects from chemical and non-chemical stressors.We recommend using updated methods and data to improve consideration of human variability and susceptibility in risk assessment, including the use of increased default human variability factors and separate adjustment factors for capturing age/life stage of development and exposure to multiple chemical and non-chemical stressors. Updated methods would result in greater transparency and protection for susceptible groups, including children, infants, people who are pregnant or nursing, people with disabilities, and those burdened by additional environmental exposures and/or social factors such as poverty and racism.

Air Pollution: Possible Interaction between the Immune and Nervous System?

Exposure to environmental pollutants is a serious and common public health concern associated with growing morbidity and mortality worldwide, as well as economic burden. In recent years, the toxic effects associated with air pollution have been intensively studied, with a particular focus on the lung and cardiovascular system, mainly associated with particulate matter exposure. However, epidemiological and mechanistic studies suggest that air pollution can also influence skin integrity and may have a significant adverse impact on the immune and nervous system. Air pollution exposure already starts in utero before birth, potentially causing delayed chronic diseases arising later in life. There are, indeed, time windows during the life of individuals who are more susceptible to air pollution exposure, which may result in more severe outcomes. In this review paper, we provide an overview of findings that have established the effects of air pollutants on the immune and nervous system, and speculate on the possible interaction between them, based on mechanistic data.

Perspectives of ozone induced neuropathology and memory decline in Alzheimer's disease: A systematic review of preclinical evidences

This systematic review aims to discover the plausible mechanism of Ozone in A.D., to boost translational research. The main focus of our review lies in understanding the effects of ozone pollution on the human brain and causing degenerative disease. Owing to the number of works carried out as preclinical evidence in association with oxidative stress and Alzheimer's disease and the lack of systematic review or meta-analysis prompted us to initiate a study on Alzheimer's risk due to ground-level ozone. We found relevant studies from PubMed, ScienceDirect, Proquest, DOAJ, and Scopus, narrowing to animal studies and the English language without any time limit. The searches will be re-run before the final analysis. This work was registered in Prospero with Reg ID CRD42022319360, followed the PRISMA-P framework, and followed the PICO approach involving Population, Intervention/Exposure, Comparison, and Outcomes data. Bibliographic details of 16 included studies were studied for Exposure dose of ozone, duration, exposure, and frequency with control and exposure groups. Primary and secondary outcomes were assessed based on pathology significance, and results were significant in inducing Alzheimer-like pathology by ozone. In conclusion, ozone altered oxidative stress, metabolic pathway, and amyloid plaque accumulation besides endothelial stress response involving mitochondria as the critical factor in ATP degeneration, caspase pathway, and neuronal damage. Thus, ozone is a criteria pollutant to be focused on in mitigating Alzheimer's Disease pathology.

Association between air pollution and CSF sTREM2 in cognitively normal older adults: The CABLE study

Objectives

Ambient air pollution aggravates the process of Alzheimer's disease (AD) pathology. Currently, the exact inflammatory mechanisms underlying these links from clinical research remain largely unclear.

Methods

This study included 1,131 cognitively intact individuals from the Chinese Alzheimer's Biomarker and LifestylE database with data provided on cerebrospinal fluid (CSF) AD biomarkers (amyloid beta‐peptide 42 [Aβ42], total tau [t‐tau], and phosphorylated tau [p‐tau]), neuroinflammatory (CSF sTREM2), and systemic inflammatory markers (high sensitivity C‐reactive protein and peripheral immune cells). The 2‐year averaged levels of ambient fine particulate matter with diameter <2.5 μm (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) were estimated at each participant's residence. Multiple‐adjusted models were approached to detect associations of air pollution with inflammatory markers and AD‐related proteins.

Results

Ambient 2‐year averaged exposure of PM_2.5 was associated with changes of neuroinflammatory markers, that is, CSF sTREM2 (β = −0.116, p = 0.0002). Similar results were found for O₃ exposure among the elderly (β = −0.111, p = 0.0280) or urban population (β = −0.090, p = 0.0144). No significant evidence supported NO₂ related to CSF sTREM2. For potentially causal associations with accumulated AD pathologies, the total effects of PM_2.5 on CSF amyloid‐related protein (CSF Aβ42 and p‐tau/Aβ42) were partly mediated by CSF sTREM2, with proportions of 14.22% and 47.15%, respectively. Additional analyses found inverse associations between peripheral inflammatory markers with PM_2.5 and NO₂, but a positive correlation with O₃.

Interpretation

These findings demonstrated a strong link between PM_2.5 exposure and microglial dysfunction. Furthermore, CSF sTREM2 as a key mediator modulated the influences of PM_2.5 exposure on AD amyloid pathologies.

Indirect mediators of systemic health outcomes following nanoparticle inhalation exposure

The growing field of nanoscience has shed light on the wide diversity of natural and anthropogenic sources of nano-scale particulates, raising concern as to their impacts on human health. Inhalation is the most robust route of entry, with nanoparticles (NPs) evading mucociliary clearance and depositing deep into the alveolar region. Yet, impacts from inhaled NPs are evident far outside the lung, particularly on the cardiovascular system and highly vascularized organs like the brain. Peripheral effects are partly explained by the translocation of some NPs from the lung into the circulation; however, other NPs largely confined to the lung are still accompanied by systemic outcomes. Omic research has only just begun to inform on the complex myriad of molecules released from the lung to the blood as byproducts of pulmonary pathology. These indirect mediators are diverse in their molecular make-up and activity in the periphery. The present review examines systemic outcomes attributed to pulmonary NP exposure and what is known about indirect pathological mediators released from the lung into the circulation. Further focus was directed to outcomes in the brain, a highly vascularized region susceptible to acute and longer-term outcomes. Findings here support the need for big-data toxicological studies to understand what drives these health outcomes and better predict, circumvent, and treat the potential health impacts arising from NP exposure scenarios.

Measurement of Blood-Brain Barrier Disruption in Mice Following Ozone Exposure Using Highly Sensitive Radiotracer Assays

Ozone is a widespread air toxicant. Although its primary target organ is the lungs, emerging evidence suggests that ozone also has harmful effects on the brain. The vascular blood-brain barrier (BBB), an endothelial interface that regulates passage of substances between the brain and peripheral tissues, is a likely mediator of ozone's adverse effects on the brain. Ozone can cause BBB disruption, a pathological state in which the BBB becomes leaky, resulting in the unregulated entry of circulating substances into the brain. BBB disruption can be detected using many methods, which each have their strengths and limitations. Recent data suggest that BBB disruption can occur in mice following ozone exposures, albeit at a low level. Therefore, robust and highly sensitive assays for BBB disruption are needed. Assays commonly used to detect BBB disruption, however, can be time consuming, lack sensitivity, and can be vulnerable to artifacts that are typically not addressed in the experimental design. Radiochemical assays are among the most sensitive and specific for detecting subtle disruptions of the BBB and require minimal sample processing for detection. Radiochemical assays can also be multiplexed to include radiotracer conjugates of large and small molecular weights, and the uptake of each of them can provide information about the severity and mechanism of BBB disruption. Here, we describe a protocol to use two of these radiotracer conjugates, ¹⁴ C-sucrose and ^99m Tc- albumin, to measure BBB disruption following an acute exposure to ozone in mice. We provide the steps to expose mice acutely to ozone, to label albumin with ^99m Tc-pertechnetate, and to measure BBB disruption by evaluating permeability to ^99m Tc-albumin and ¹⁴ C-sucrose after ozone exposure. These methods can be adapted to different ozone exposure paradigms and to different rodent species/strains, allowing for the sensitive and rapid assessment of BBB disruption that is detectable in whole brains or in brain regions. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Ozone exposures in mice Basic Protocol 2: Measurement of blood-brain barrier disruption by evaluating permeability to ¹⁴ C-sucrose and ^99m Tc-albumin Support Protocol: Labeling of bovine serum albumin with ^99m Tc.

Induction of Accelerated Aging in a Mouse Model

With the global increase of the elderly population, the improvement of the treatment for various aging-related diseases and the extension of a healthy lifespan have become some of the most important current medical issues. In order to understand the developmental mechanisms of aging and aging-related disorders, animal models are essential to conduct relevant studies. Among them, mice have become one of the most prevalently used model animals for aging-related studies due to their high similarity to humans in terms of genetic background and physiological structure, as well as their short lifespan and ease of reproduction. This review will discuss some of the common and emerging mouse models of accelerated aging and related chronic diseases in recent years, with the aim of serving as a reference for future application in fundamental and translational research.

Neuroinflammatory and Neurometabolomic Consequences From Inhaled Wildfire Smoke-Derived Particulate Matter in the Western United States

Utilizing a mobile laboratory located >300 km away from wildfire smoke (WFS) sources, this study examined the systemic immune response profile, with a focus on neuroinflammatory and neurometabolomic consequences, resulting from inhalation exposure to naturally occurring wildfires in California, Arizona, and Washington in 2020. After a 20-day (4 h/day) exposure period in a mobile laboratory stationed in New Mexico, WFS-derived particulate matter (WFPM) inhalation resulted in significant neuroinflammation while immune activity in the peripheral (lung, bone marrow) appeared to be resolved in C57BL/6 mice. Importantly, WFPM exposure increased cerebrovascular endothelial cell activation and expression of adhesion molecules (VCAM-1 and ICAM-1) in addition to increased glial activation and peripheral immune cell infiltration into the brain. Flow cytometry analysis revealed proinflammatory phenotypes of microglia and peripheral immune subsets in the brain of WFPM-exposed mice. Interestingly, endothelial cell neuroimmune activity was differentially associated with levels of PECAM-1 expression, suggesting that subsets of cerebrovascular endothelial cells were transitioning to resolution of inflammation following the 20-day exposure. Neurometabolites related to protection against aging, such as NAD+ and taurine, were decreased by WFPM exposure. Additionally, increased pathological amyloid-beta protein accumulation, a hallmark of neurodegeneration, was observed. Neuroinflammation, together with decreased levels of key neurometabolites, reflect a cluster of outcomes with important implications in priming inflammaging and aging-related neurodegenerative phenotypes.

Long-term ozone exposure and cognitive impairment among Chinese older adults: A cohort study

Ambient particulate matter pollution has been linked to impaired cognitive performance, but the effect of ambient ozone exposure on cognitive function remains largely unknown. We examined the association of long-term ozone exposure with the risk of cognitive impairment among a national representative cohort of 9,544 Chinese older adults (aged 65 years and over) with baseline normal cognition from the Chinese Longitudinal Healthy Longevity Survey (2005-2018). The ozone exposure of each participant was measured by annual mean ozone concentrations for the county of residence. Cognitive function was assessed by the Chinese version of the Mini-Mental State Examination (MMSE). We defined cognitive impairment as an MMSE score below 18 points accompanied by an MMSE score that declined ≥ 4 points from baseline. Cox proportional hazards models were applied to explore the association of ozone exposure with cognitive impairment. During the mean follow-up time of 6.5 years, 2,601 older adults developed cognitive impairment. Each 10-μg/m³ increase in annual mean ozone exposure was associated with a 10.4% increased risk of cognitive impairment. The exposure-response relationship between ozone exposure and risk of cognitive impairment showed a linear trend. Sensitivity analyses revealed the association to be robust. We found that older adults from Eastern, Central, and Southern China were particularly susceptible. Our results show that ozone is a risk factor for late-life cognitive decline. Reducing ambient ozone pollution may help delay the onset of cognitive impairment among older adults.

Systematic review of preclinical studies on the neutrophil-mediated immune response to air pollutants, 1980-2020

Preclinical evidence about the neutrophil-mediated response in exposure to air pollutants is scattered and heterogeneous. This has prevented the consolidation of this research field around relevant models that could advance towards clinical research. The purpose of this study was to systematic review the studies of the neutrophils response to air pollutants, following the recommendations of the Cochrane Collaboration and the PRISMA guide, through 54 search strategies in nine databases. We include 234 studies (in vitro, and in vivo), being more frequent using primary neutrophils, Balb/C and C57BL6/J mice, and Sprague-Dawley and Wistar rats. The most frequent readouts were cell counts, cytokines and histopathology. The temporal analysis showed that in the last decade, the use of mice with histopathological and cytokine measurement have predominated. This systematic review has shown that study of the neutrophils response to air pollutants started 40 years ago, and composed of 100 different preclinical models, 10 pollutants, and 11 immunological outcomes. Mechanisms of neutrophils-mediated immunopathology include cellular activation, ROS production, and proinflammatory effects, leading to cell-death, oxidative stress, and inflammatory infiltrates in lungs. This research will allow consolidating the research efforts in this field, optimizing the study of causal processes, and facilitating the advance to clinical studies.

Effects and mechanisms of probucol on aging-related hippocampus-dependent cognitive impairment

BACKGROUND

In the present study, we aimed to investigate the effects of probucol on aging-related hippocampus-dependent cognitive impairment and explore the potential mechanisms.

METHODS

D-galactose (100 mg/kg, once daily for 6 weeks) was subcutaneously injected to induce aging in mice. Then the mice were administered with probucol or vehicle once a day for 2 weeks. The hippocampus-related cognition was evaluated with Morris water maze test, novel object recognition test, and contextual fear conditioning test. Moreover, synaptic plasticity was assessed, and RNA-sequencing was applied to further explore the molecular mechanisms.

RESULTS

Aging mice induced by D-galactose showed conspicuous learning and memory impairment, which was significantly ameliorated by probucol. Meanwhile, probucol enhanced the spine density and dendritic branches, improved long-term potentiation, and increased the expression of PSD95 of aging mice. Probucol regulated 70 differentially expressed genes compared to D-galactose group, of which 38 genes were upregulated and 32 genes were downregulated. At last, RNA-sequencing results were verified by quantitative reverse transcription-polymerase chain reaction.

CONCLUSIONS

Probucol improved learning and memory in aging mice through enhancing synaptic plasticity and regulating gene expression, indicating the potential application of probucol to prevent and treat aging-related disorders.

Air Pollution Neurotoxicity in the Adult Brain: Emerging Concepts from Experimental Findings

Epidemiological studies are associating elevated exposure to air pollution with increased risk of Alzheimer's disease and other neurodegenerative disorders. In effect, air pollution accelerates many aging conditions that promote cognitive declines of aging. The underlying mechanisms and scale of effects remain largely unknown due to its chemical and physical complexity. Moreover, individual responses to air pollution are shaped by an intricate interface of pollutant mixture with the biological features of the exposed individual such as age, sex, genetic background, underlying diseases, and nutrition, but also other environmental factors including exposure to cigarette smoke. Resolving this complex manifold requires more detailed environmental and lifestyle data on diverse populations, and a systematic experimental approach. Our review aims to summarize the modest existing literature on experimental studies on air pollution neurotoxicity for adult rodents and identify key gaps and emerging challenges as we go forward. It is timely for experimental biologists to critically understand prior findings and develop innovative approaches to this urgent global problem. We hope to increase recognition of the importance of air pollution on brain aging by our colleagues in the neurosciences and in biomedical gerontology, and to support the immediate translation of the findings into public health guidelines for the regulation of remedial environmental factors that accelerate aging processes.

Ozone-induced encephalopathy: A novel iatrogenic entity

BACKGROUND AND PURPOSE

Ozone-based treatments can be associated with central nervous system toxicity, which we have termed ozone-induced encephalopathy (OIE). A detailed description of its phenotype is lacking.

METHODS

Three cases with findings suggestive of OIE are presented, and the literature is reviewed.

RESULTS

Case 1 is a healthy 59-year-old man presenting with loss of consciousness, cortical blindness, restlessness, and anterograde amnesia immediately following a cervical ozone-therapy (OT) session for chronic neck pain. Brain magnetic resonance imaging (MRI) on admission was normal. A follow-up scan demonstrated a subtle increased T2 fluid-attenuated inversion recovery signal within the left cerebellum; an echocardiography showed a patent foramen ovale (PFO). Case 2 is a 56-year-old woman with history of migraine, PFO, and lumbar pain who presented with headache, bilateral visual impairment, motor dysphasia, and agitation. All her symptoms began immediately after lumbar OT. Her brain MRI was negative. Case 3 is a healthy 27-year-old man who complained of vertigo and mild blurred vision 5 min following a cervical ozone injection. His neurological examination and brain MRI were normal. All three patients had full recovery within 48 h. We found eight additional cases of OIE in the literature.

CONCLUSIONS

OIE should be considered in patients presenting with neurological symptoms in close relation to OT. OIE is likely a novel iatrogenic entity with a complex pathogenesis; it is probably underreported because it mimics other neurological conditions.

Natural products present neurotrophic properties in neurons of the limbic system in aging rodents

Aging is a complex process that can lead to neurodegeneration and, consequently, several pathologies, including dementia. Physiological aging leads to changes in several body organs, including those of the central nervous system (CNS). Morphological changes in the CNS and particularly the brain result in motor and cognitive deficits affecting learning and memory and the circadian cycle. Characterizing neural modifications is critical to designing new therapies to target aging and associated pathologies. In this review, we compared aging to the changes occurring within the brain and particularly the limbic system. Then, we focused on key natural compounds, apamin, cerebrolysin, Curcuma longa, resveratrol, and N-PEP-12, which have shown neurotrophic effects particularly in the limbic system. Finally, we drew our conclusions delineating future perspectives for the development of novel natural therapeutics to ameliorate aging-related processes.

Serum-borne factors alter cerebrovascular endothelial microRNA expression following particulate matter exposure near an abandoned uranium mine on the Navajo Nation

Background

Commercial uranium mining on the Navajo Nation has subjected communities on tribal lands in the Southwestern United States to exposures from residual environmental contamination. Vascular health effects from these ongoing exposures are an active area of study. There is an association between residential mine-site proximity and circulating biomarkers in residents, however, the contribution of mine-site derived wind-blown dusts on vascular and other health outcomes is unknown. To assess neurovascular effects of mine-site derived dusts, we exposed mice using a novel exposure paradigm, the AirCARE1 mobile inhalation laboratory, located 2 km from an abandoned uranium mine, Claim 28 in Blue Gap Tachee, AZ. Mice were exposed to filtered air (FA) (n = 6) or concentrated ambient particulate matter (CAPs) (n = 5) for 2 wks for 4 h per day.

Results

To assess miRNA differential expression in cultured mouse cerebrovascular cells following particulate matter (PM) exposure (average: 96.6 ± 60.4 μg/m³ for all 4 h exposures), the serum cumulative inflammatory potential (SCIP) assay was employed. MiRNA sequencing was then performed in cultured mouse cerebrovascular endothelial cells (mCECs) to evaluate transcriptional changes. Results indicated 27 highly differentially expressed (p < 0.01) murine miRNAs, as measured in the SCIP assay. Gene ontology (GO) pathway analysis revealed notable alterations in GO enrichment related to the cytoplasm, protein binding and the cytosol, while significant KEGG pathways involved pathways in cancer, axon guidance and Wnt signaling. Expression of these 27 identified, differentially expressed murine miRNAs were then evaluated in the serum. Nine of these miRNAs (~ 30%) were significantly altered in the serum and 8 of those miRNAs demonstrated the same directional change (either upregulation or downregulation) as cellular miRNAs, as measured in the SCIP assay. Significantly upregulated miRNAs in the CAPs exposure group included miRNAs in the let-7a family. Overexpression of mmu-let-7a via transfection experiments, suggested that this miRNA may mediate mCEC barrier integrity following dust exposure.

Conclusions

Our data suggest that mCEC miRNAs as measured in the SCIP assay show similarity to serum-borne miRNAs, as approximately 30% of highly differentially expressed cellular miRNAs in the SCIP assay were also found in the serum. While translocation of miRNAs via exosomes or an alternative mechanism is certainly possible, other yet-to-be-identified factors in the serum may be responsible for significant miRNA differential expression in endothelium following inhaled exposures. Additionally, the most highly upregulated murine miRNAs in the CAPs exposure group were in the let-7a family. These miRNAs play a prominent role in cell growth and differentiation and based on our transfection experiments, mmu-let-7a may contribute to cerebrovascular mCEC alterations following inhaled dust exposure.

Toxicity of urban air pollution particulate matter in developing and adult mouse brain: Comparison of total and filter-eluted nanoparticles

Air pollution (AirP) is associated with many neurodevelopmental and neurological disorders in human populations. Rodent models show similar neurotoxic effects of AirP particulate matter (PM) collected by different methods or from various sources. However, controversies continue on the identity of the specific neurotoxic components and mechanisms of neurotoxicity. We collected urban PM by two modes at the same site and time: direct collection as an aqueous slurry (sPM) versus a nano-sized sub-fraction of PM0.2 that was eluted from filters (nPM). The nPM lacks water-insoluble PAHs (polycyclic aromatic hydrocarbons) and is depleted by >50% in bioactive metals (e.g., copper, iron, nickel), inorganic ions, black carbon, and other organic compounds. Three biological models were used: in vivo exposure of adult male mice to re-aerosolized nPM and sPM for 3 weeks, gestational exposure, and glial cell cultures. In contrast to larger inflammatory responses of sPM in vitro, cerebral cortex responses of mice to sPM and nPM largely overlapped for adult and gestational exposures. Adult brain responses included induction of IFNγ and NF-κB. Gestational exposure to nPM and sPM caused equivalent depressive behaviors. Responses to nPM and sPM diverged for cerebral cortex glutamate receptor mRNA, systemic fat gain and insulin resistance. The shared toxic responses of sPM with nPM may arise from shared transition metals and organics. In contrast, gestational exposure to sPM but not nPM, decreased glutamatergic mRNAs, which may be attributed to PAHs. We discuss potential mechanisms in the overlap between nPM and sPM despite major differences in bulk chemical composition.

Stress hormones as potential mediators of air pollutant effects on the brain: Rapid induction of glucocorticoid-responsive genes

Air pollution is associated with adverse effects on brain health including cognitive decline, dementia, anxiety, depression, and suicide. While toxicological studies have demonstrated the potential for repeated or chronic pollutant exposure to lead to disease states, characterisation of initial biological responses to exposure is needed to better understand underlying mechanisms. The brain is highly sensitive to glucocorticoids (primarily cortisol in humans, corticosterone in rodents), stress hormones that play important roles in cognition and mental health. We tested whether glucocorticoids could be implicated in central nervous system (CNS) effects of pollutant exposure by examining glucocorticoid-dependent signaling across brain regions after exposure to the common pollutant ozone. Male Fischer-344 rats were exposed for 4 h to air or 0.8 ppm ozone ± metyrapone (50 mg/kg), a drug that blocks corticosterone synthesis (n = 5/group). Key glucocorticoid-responsive genes (serum- and glucocorticoid-inducible kinase, SGK; glucocorticoid-inducible leucine zipper, GILZ), and a gene responsive to both glucocorticoids and oxidative stress (metallothionein (MT)-1), were increased by ozone in all brain regions (olfactory bulb, frontal lobe, cortex, midbrain, hippocampus, cerebellum, brainstem), correlating with plasma corticosterone levels. Metyrapone prevented the increase in SGK and GILZ, and reduced but did not eliminate the effect on MT-1, suggesting glucocorticoid-dependent and -independent regulation. Administering exogenous corticosterone (10 mg/kg) to air-exposed rats reproduced the ozone effects, confirming specificity. The results demonstrate that early pollutant effects include stress hormone-dependent signaling. As both ozone and particulate matter activate the hypothalamic-pituitary-adrenal axis, and elevated glucocorticoids are implicated in brain pathologies, stress hormones could contribute to CNS impacts of air pollutants.

Ozone-induced dysregulation of neuroendocrine axes requires adrenal-derived stress hormones

Acute ozone inhalation increases circulating stress hormones through activation of the sympathetic-adrenal-medullary and hypothalamic-pituitary-adrenal axes. Adrenalectomized (AD) rats have attenuated ozone-induced lung responses. We hypothesized that ozone exposure will induce changes in circulating pituitary-derived hormones and global gene expression in the brainstem and hypothalamus, and that AD will ameliorate these effects. Male Wistar-Kyoto rats (13-weeks) that underwent sham-surgery (SHAM) or AD were exposed to ozone (0.8-ppm) or filtered-air for 4-hours. In SHAM rats, ozone exposure decreased circulating thyroid-stimulating hormone (TSH), prolactin (PRL), and luteinizing hormone (LH). AD prevented reductions in TSH and PRL, but not LH. AD increased ACTH ∼5-fold in both air and ozone-exposed rats. AD in air-exposed rats resulted in few significant transcriptional differences in the brainstem and hypothalamus (∼20 genes per tissue). By contrast, ozone-exposure in SHAM rats resulted in increases and decreases in expression of hundreds of genes in brainstem and hypothalamus relative to air-exposed SHAM rats (303 and 568 genes, respectively). Differentially expressed genes from ozone exposure were enriched for pathways involving hedgehog signaling, responses to alpha-interferon, hypoxia, and mTORC1, among others. Gene changes in both brain areas were analogous to those altered by corticosteroids and L-dopa, suggesting a role for endogenous glucocorticoids and catecholamines. AD completely prevented this ozone-induced transcriptional response. These findings show that short-term ozone inhalation promotes a shift in brainstem and hypothalamic gene expression that is dependent on the presence of circulating adrenal-derived stress hormones. This is likely to have profound downstream influence on systemic effects of ozone.

Alzheimer and depressive cognitive-like behaviors in male and female rats: A new method for exposure to ambient air pollution

In the previous studies regarding the effects of exposure to ambient air pollution on biological markers and/or behavior of animals, the gaseous pollutants are not separated from the particulate matter (PM). Hence the synergetic effect of gaseous pollutants and PM was not considered. In this regard, current study was aimed to devolve a new method for separation of PM from gaseous pollutants. Also, the effect of exposure to fine particulate matter (PM_2.5) on the Alzheimer and depressive cognitive-like behaviors in rats after 3 and 6 months were investigated. Three chambers were designed including exposure group 1 (PM_2.5 plus gaseous pollutants alone), exposure group 2 (gaseous pollutants alone) and control group (clean air). Exposure time was 5 h per day (9.00 a.m.-2.00 p.m.) for 4 days per week. The concentration of PM_2.5 and gaseous pollutants (O₃, NO₂, and SO₂) were monitored in the exposure hours, continuously. Concentration of PM_2.5 by beta attenuation method and concentration of O₃, NO₂, and SO₂ by UV fluorescence was monitored. Also, the concentration of metals including Al, Cr, Mn, Pb, Cd, Ni, Fe, and Cu and 16-polycyclic aromatic hydrocarbons (PAHs) bound PM_2.5 by inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC-MS) were analyzed, respectively. Cognitive-like behavior related to Alzheimer and depressive behaviors were determined by Y maze and Force swimming. The concentration of PM_2.5 in the 3 and 6 months exposure was higher than WHO guideline, significantly (p-value <0.05). The concentration of O₃, NO₂ and SO₂ in the 3 and 6 months exposure was lower than WHO guideline, significantly (p-value <0.05). The order of metals in the PM_2.5 according to mean concentration Al > Ca > Cu > Cd > Na > Fe > Cr > Ni > Mn > Pb. Also, the sum concentration of 16-PAHs in the PM_2.5 in the 3 and 6 months exposure was 45.7 ± 37.15 ng/m³ and 30.04 ± 25.27 ng/m³, respectively. Exposure to PM_2.5 cannot significantly increase Alzheimer and depressive cognitive-like behaviors in the rats. Also, a significant difference between male and female in Alzheimer and depressive cognitive-like behaviors not observed. •A new method for separation of PM_2.5 from other PM in the ambient air by ECO-PM sampler was presented.•A new method for separation of PM_2.5 from gaseous pollutants in the ambient air by HEPA filter and active carbon was presented.•Tow exposure groups including exposure 1: PM_2.5 plus gaseous pollutants and exposure 2: gaseous pollutants only were designed for increased accuracy of the in-vivo study.•Exposure to PM_2.5 cannot cause significant increased Alzheimer and depressive cognitive-like behaviors in the rats.

Development of a large-scale computer-controlled ozone inhalation exposure system for rodents

Objective: Complete systems for laboratory-based inhalation toxicology studies are typically not commercially available; therefore, inhalation toxicologists utilize custom-made exposure systems. Here we report on the design, construction, testing, operation and maintenance of a newly developed in vivo rodent ozone inhalation exposure system. Materials and methods: Key design requirements for the system included large-capacity exposure chambers to facilitate studies with large sample sizes, automatic and precise control of chamber ozone concentrations, as well as automated data collection on airflow and environmental conditions. The exposure system contains two Hazelton H-1000 stainless steel and glass exposure chambers, each providing capacity for up to 180 mice or 96 rats. We developed an empirically tuned proportional-integral-derivative control loop that provides stable ozone concentrations throughout the exposure period (typically 3h), after a short ramp time (∼8 min), and across a tested concentration range of 0.2-2 ppm. Specific details on the combination of analog and digital input/output system for environmental data acquisition, control and safety systems are provided, and we outline the steps involved in maintenance and calibration of the system. Results: We show that the exposure system produces consistent ozone exposures both within and across experiments, as evidenced by low coefficients of variation in chamber ozone concentration and consistent biological responses (airway inflammation) in mice, respectively. Conclusion: Thus, we have created a large and robust ozone exposure system, facilitating future studies on the health effects of ozone in rodents.

111In-DANBIRT In Vivo Molecular Imaging of Inflammatory Cells in Atherosclerosis

Atherosclerosis-related morbidity and mortality remain a global concern. Atherosclerotic disease follows a slow and silent progression, and the transition from early-stage lesions to vulnerable plaques remains difficult to diagnose. Inflammation is a key component of the development of atherosclerotic plaque and consequent life-threatening complications. This study assessed ¹¹¹In-DANBIRT as an in vivo, noninvasive SPECT/CT imaging probe targeting an inflammatory marker, Lymphocyte Function Associated Antigen-1 (LFA-1), in atherosclerotic plaques. Methods. Selective binding of ¹¹¹In-DANBIRT was assessed using Sprague-Dawley rats exposed to filtered air and ozone (1 ppm) by inhalation for 4 hours to induce a circulating leukocytosis and neutrophilia in peripheral blood. After 24 hours, whole blood was collected and incubated with radiolabeled DANBIRT (⁶⁸Ga-DANBIRT and ¹¹¹In-DANBIRT). Isolated cell component smeared slides using cytospin technique were stained with Wright-Giemsa stain. Apolipoprotein E-deficient (apoE^−/−) mice were fed either a normal diet or a high-fat diet (HFD) for 8 weeks. Longitudinal SPECT/CT imaging was performed 3 hours after administration at baseline, 4, and 8 weeks of HFD diet, followed by tissue harvesting for biodistribution, serum lipid analysis, and histology. 3D autoradiography was performed in both groups 24 hours after administration of ¹¹¹In-DANBIRT. Results. Increased specific uptake of radiolabeled DANBIRT by neutrophils in the ozone-exposed group was evidenced by the acute immune response due to 4-hour ozone exposure. Molecular imaging performed at 3 hours using SPECT/CT imaging evidenced an exponential longitudinal increase in ¹¹¹In-DANBIRT uptake in atherosclerosis lesions in HFD-fed mice compared to normal-diet-fed mice. Such results were consistent with increased immune response to vascular injury in cardiovascular and also immune tissues, correlated by 24 hours after administration of 3D autoradiography. Histologic analysis confirmed atherosclerotic disease progression with an increased vascular lesion area in HFD-fed mice compared to normal-diet-fed mice. Conclusion. ¹¹¹In-DANBIRT is a promising molecular imaging probe to assess inflammation in evolving atheroma and atherosclerotic plaque.

Ambient Pollutants and Spontaneous Intracerebral Hemorrhage in Greater Boston

Background and Purpose- Associations between exposures to ambient air pollution and spontaneous intracerebral hemorrhage (ICH) have been inconsistent, and data on stroke subtypes are currently limited. Methods- We obtained information on all cases of deep or lobar hematomas from ICH patients who were admitted to the Massachusetts General Hospital in Boston, MA, between 2006 and 2011. We linked the date of admission with 1- to 7-day moving averages of fine particulate matter (PM2.5), black carbon, nitrogen dioxide, and ozone from area monitors. We conducted time-stratified bidirectional case-crossover analyses to assess associations between pollutants and stroke. We also investigated whether associations differed by hemorrhage location and type. Results- There were 577 cases of ICH (295 deep, 282 lobar). Overall, there was no evidence of elevated ICH risk after increases in PM2.5, black carbon, or nitrogen dioxide in the whole population. However, there was suggestion of heightened risk with higher levels of ozone for averages longer than 1 day although CIs were wide. In models stratified by ICH location, associations with ozone remained positive for patients with lobar (3-day moving average odds ratio, 1.62; 95% CI, 1.18-2.22) but not deep ICH (odds ratio, 0.88; 95% CI, 0.65-1.20). Larger estimates were observed among participants with a probable diagnosis of cerebral amyloid angiopathy (odds ratio, 2.23; 95% CI, 1.25-3.96). Conclusions- Exposure to ozone may be associated with incidence of lobar ICH, especially among those who have confirmed or probable cerebral amyloid angiopathy.

Commentary on the 2018 Named Series on blood-brain interfaces: Roles of neuroimmunomodulation in health and disease

This year's 2018 Named Series on blood-brain interfaces highlights the importance of brain barriers as mediators of neuroimmune communication and regulators of neurological function. The term "brain interfaces" reflects our growing understanding that brain barriers such as the blood-brain barrier (BBB) and blood-CSF barrier (BCSFB) are not only gatekeepers, but facilitators of bidirectional communication between the brain and periphery. There is also an emerging appreciation that CNS sites that are exposed to blood-borne immune molecules and cells, such as the leptomeninges and circumventricular organs, may also be considered brain interfaces with important homeostatic and pathological functions. The work featured in this Series covers novel aspects of brain interface functions that focus on mechanisms regulating barrier integrity and transporter activities, downstream consequences of neurovascular injury, peripheral organ infection/injury, and clearance of pathogenic proteins. Results of these studies have emphasized new mechanisms by which brain interface dysfunction could contribute to neuroinflammation and CNS damage in eclampsia, fetal and adult hypoxic/ischemic injury, traumatic brain injury, Helicobacter infections, acute lung injury, multiple sclerosis, and Alzheimer's disease. This body of work emphasizes that brain interfaces may themselves be important therapeutic targets for a variety of CNS diseases that are associated with immune dyshomeostasis. Future works are warranted to further investigate brain interface functions in health and disease.