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The laboratory mouse is often used as a human surrogate in aerosol inhalation studies. Morphometric data on the tracheobronchial geometry of three in situ lung casts of the Balb/c mouse lung produced by the Air Pollution Health Effects Laboratory were analyzed in terms of probability density functions and correlations among the different airway parameters. The results of this statistical analysis reveal significant differences in diameters and branching angles between major and minor progeny branching off from the same parent airway at a given airway bifurcation. Number of bronchial airways generations along a given path, expressed by the termination probability, branching angles, and daughter-to-parent diameter ratios indicate that the location of an airway with defined linear airway dimensions within the lung is more appropriately identified by its diameter (or its parent diameter) than by an assigned generation number. We, therefore, recommend classifying the mouse lung airways by their diameters and not by generation numbers, consistent with our previous analysis of the rather monopodial structure of the rat lung (Koblinger et al., J Aerosol Med 1995;8:7–19; Koblinger and Hofmann, J Aerosol Med 1995;8:21–32). Because of lack of corresponding information on respiratory airways, a partly stochastic symmetric acinar airway model was attached to the tracheobronchial model, in which the number of acinar airways along a given path was randomly selected from a measured acinar volume distribution. The computed distributions of the geometric airway parameters and their correlations will be used for random pathway selection of inhaled particles in subsequent Monte Carlo deposition calculations., (Copyright © 2010 Wiley-Liss, Inc.)

The human cortex contains inhibitory interneurons derived from the medial ganglionic eminence (MGE), a germinal zone in the embryonic ventral forebrain. How this germinal zone generates sufficient interneurons for the human brain remains unclear. We found that the human MGE (hMGE) contains nests of proliferative neuroblasts with ultrastructural and transcriptomic features that distinguish them from other progenitors in the hMGE. When dissociated hMGE cells are transplanted into the neonatal mouse brain, they reform into nests containing proliferating neuroblasts that generate young neurons that migrate extensively into the mouse forebrain and mature into different subtypes of functional interneurons. Together, these results indicate that the nest organization and sustained proliferation of neuroblasts in the hMGE provide a mechanism for the extended production of interneurons for the human forebrain.

Blood vessels in the CNS form a specialized and critical structure, the blood-brain barrier (BBB). We present a resource to understand the molecular mechanisms that regulate BBB function in health and dysfunction during disease. Using endothelial cell enrichment and RNA sequencing, we analyzed the gene expression of endothelial cells in mice, comparing brain endothelial cells with peripheral endothelial cells. We also assessed the regulation of CNS endothelial gene expression in models of stroke, multiple sclerosis, traumatic brain injury and seizure, each having profound BBB disruption. We found that although each is caused by a distinct trigger, they exhibit strikingly similar endothelial gene expression changes during BBB disruption, comprising a core BBB dysfunction module that shifts the CNS endothelial cells into a peripheral endothelial cell-like state. The identification of a common pathway for BBB dysfunction suggests that targeting therapeutic agents to limit it may be effective across multiple neurological disorders.

It is widely assumed that cells must be physically isolated to study their molecular profiles. However, intact tissue samples naturally exhibit variation in cellular composition, which drives covariation of cell-class-specific molecular features. By analyzing transcriptional covariation in 7,221 intact CNS samples from 840 neurotypical individuals, representing billions of cells, we reveal the core transcriptional identities of major CNS cell classes in humans. By modeling intact CNS transcriptomes as a function of variation in cellular composition, we identify cell-class-specific transcriptional differences in Alzheimer's disease, among brain regions, and between species. Among these, we show that PMP2 is expressed by human but not mouse astrocytes and significantly increases mouse astrocyte size upon ectopic expression in vivo, causing them to more closely resemble their human counterparts. Our work is available as an online resource ( http://oldhamlab.ctec.ucsf.edu/ ) and provides a generalizable strategy for determining the core molecular features of cellular identity in intact biological systems.

The neocortex of primates, including humans, contains more abundant and diverse inhibitory neurons compared with rodents, but the molecular foundations of these observations are unknown. Through integrative gene coexpression analysis, we determined a consensus transcriptional profile of GABAergic neurons in mid-gestation human neocortex. By comparing this profile to genes expressed in GABAergic neurons purified from neonatal mouse neocortex, we identified conserved and distinct aspects of gene expression in these cells between the species. We show here that the calcium-binding protein secretagogin (SCGN) is robustly expressed by neocortical GABAergic neurons derived from caudal ganglionic eminences (CGE) and lateral ganglionic eminences during human but not mouse brain development. Through electrophysiological and morphometric analyses, we examined the effects of SCGN expression on GABAergic neuron function and form. Forced expression of SCGN in CGE-derived mouse GABAergic neurons significantly increased total neurite length and arbor complexity following transplantation into mouse neocortex, revealing a molecular pathway that contributes to morphological differences in these cells between rodents and primates.

Gliomas comprise heterogeneous malignant glial and stromal cells. While blood vessel co-option is a potential mechanism to escape anti-angiogenic therapy, the relevance of glial phenotype in this process is unclear. We show that Olig2+ oligodendrocyte precursor-like glioma cells invade by single-cell vessel co-option and preserve the blood-brain barrier (BBB). Conversely, Olig2-negative glioma cells form dense perivascular collections and promote angiogenesis and BBB breakdown, leading to innate immune cell activation. Experimentally, Olig2 promotes Wnt7b expression, a finding that correlates in human glioma profiling. Targeted Wnt7a/7b deletion or pharmacologic Wnt inhibition blocks Olig2+ glioma single-cell vessel co-option and enhances responses to temozolomide. Finally, Olig2 and Wnt7 become upregulated after anti-VEGF treatment in preclinical models and patients. Thus, glial-encoded pathways regulate distinct glioma-vascular microenvironmental interactions.

Mammalian lungs are comprised of large numbers of tracheobronchial airways that transition from the trachea to alveoli. Studies as wide ranging as pollutant deposition and lung development rely on accurate characterization of these airways. Advancements in CT imaging and the value of computational approaches in eliminating the burden of manual measurement are providing increased efficiency in obtaining this geometric data. In this study, we compare an automated method to a manual one for the first six generations of three Balb/c mouse lungs. We find good agreement between manual and automated methods and that much of the disagreement can be attributed to method precision. Using the automated method, we then provide anatomical data for the entire tracheobronchial airway tree from three Balb/C mice. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:2046-2057, 2017. © 2017 Wiley Periodicals, Inc.

Tissue homeostasis requires the production of newly differentiated cells from resident adult stem cells. Central to this process is the expansion of undifferentiated intermediates known as transit-amplifying (TA) cells, but how stem cells are triggered to enter this proliferative TA state remains an important open question. Using the continuously growing mouse incisor as a model of stem cell-based tissue renewal, we found that the transcriptional cofactors YAP and TAZ are required both to maintain TA cell proliferation and to inhibit differentiation. Specifically, we identified a pathway involving activation of integrin α3 in TA cells that signals through an LATS-independent FAK/CDC42/PP1A cascade to control YAP-S397 phosphorylation and nuclear localization. This leads to Rheb expression and potentiates mTOR signaling to drive the proliferation of TA cells. These findings thus reveal a YAP/TAZ signaling mechanism that coordinates stem cell expansion and differentiation during organ renewal.

Investigations into stem cell-fueled renewal of an organ benefit from an inventory of cell type-specific markers and a deep understanding of the cellular diversity within stem cell niches. Using the adult mouse incisor as a model for a continuously renewing organ, we performed an unbiased analysis of gene co-expression relationships to identify modules of co-expressed genes that represent differentiated cells, transit-amplifying cells, and residents of stem cell niches. Through in vivo lineage tracing, we demonstrated the power of this approach by showing that co-expression module members Lrig1 and Igfbp5 define populations of incisor epithelial and mesenchymal stem cells. We further discovered that two adjacent mesenchymal tissues, the periodontium and dental pulp, are maintained by distinct pools of stem cells. These findings reveal novel mechanisms of incisor renewal and illustrate how gene co-expression analysis of intact biological systems can provide insights into the transcriptional basis of cellular identity.

Microglia maintain homeostasis in the brain, but whether aberrant microglial activation can cause neurodegeneration remains controversial. Here, we use transcriptome profiling to demonstrate that deficiency in frontotemporal dementia (FTD) gene progranulin (Grn) leads to an age-dependent, progressive upregulation of lysosomal and innate immunity genes, increased complement production, and enhanced synaptic pruning in microglia. During aging, Grn(-/-) mice show profound microglia infiltration and preferential elimination of inhibitory synapses in the ventral thalamus, which lead to hyperexcitability in the thalamocortical circuits and obsessive-compulsive disorder (OCD)-like grooming behaviors. Remarkably, deleting C1qa gene significantly reduces synaptic pruning by Grn(-/-) microglia and mitigates neurodegeneration, behavioral phenotypes, and premature mortality in Grn(-/-) mice. Together, our results uncover a previously unrecognized role of progranulin in suppressing aberrant microglia activation during aging. These results represent an important conceptual advance that complement activation and microglia-mediated synaptic pruning are major drivers, rather than consequences, of neurodegeneration caused by progranulin deficiency.

Radial glia, the neural stem cells of the neocortex, are located in two niches: the ventricular zone and outer subventricular zone. Although outer subventricular zone radial glia may generate the majority of human cortical neurons, their molecular features remain elusive. By analyzing gene expression across single cells, we find that outer radial glia preferentially express genes related to extracellular matrix formation, migration, and stemness, including TNC, PTPRZ1, FAM107A, HOPX, and LIFR. Using dynamic imaging, immunostaining, and clonal analysis, we relate these molecular features to distinctive behaviors of outer radial glia, demonstrate the necessity of STAT3 signaling for their cell cycle progression, and establish their extensive proliferative potential. These results suggest that outer radial glia directly support the subventricular niche through local production of growth factors, potentiation of growth factor signals by extracellular matrix proteins, and activation of self-renewal pathways, thereby enabling the developmental and evolutionary expansion of the human neocortex.

The evolutionarily conserved miR-302 family of microRNAs is expressed during early mammalian embryonic development. Here, we report that deletion of miR-302a-d in mice results in a fully penetrant late embryonic lethal phenotype. Knockout embryos have an anterior neural tube closure defect associated with a thickened neuroepithelium. The neuroepithelium shows increased progenitor proliferation, decreased cell death, and precocious neuronal differentiation. mRNA profiling at multiple time points during neurulation uncovers a complex pattern of changing targets over time. Overexpression of one of these targets, Fgf15, in the neuroepithelium of the chick embryo induces precocious neuronal differentiation. Compound mutants between mir-302 and the related mir-290 locus have a synthetic lethal phenotype prior to neurulation. Our results show that mir-302 helps regulate neurulation by suppressing neural progenitor expansion and precocious differentiation. Furthermore, these results uncover redundant roles for mir-290 and mir-302 early in development.

BackgroundMixed lineage leukemia-1 (Mll1) epigenetically regulates gene expression patterns that specify cellular identity in both embryonic development and adult stem cell populations. In the adult mouse brain, multipotent neural stem cells (NSCs) in the subventricular zone generate new neurons throughout life, and Mll1 is required for this postnatal neurogenesis but not for glial cell differentiation. Analysis of Mll1-dependent transcription may identify neurogenic genes useful for the direct reprogramming of astrocytes into neurons.ObjectiveTo identify Mll1-dependent transcriptional modules and to determine whether genes in the neurogenic modules can be used to directly reprogram astrocytes into neurons.MethodsWe performed gene coexpression module analysis on microarray data from differentiating wild-type and Mll1-deleted subventricular zone NSCs. Key developmental regulators belonging to the neurogenic modules were overexpressed in Mll1-deleted cells and cultured cortical astrocytes, and cell phenotypes were analyzed by immunocytochemistry and electrophysiology.ResultsTranscriptional modules that correspond to neurogenesis were identified in wild-type NSCs. Modules related to astrocytes and oligodendrocytes were enriched in Mll1-deleted NSCs, consistent with their gliogenic potential. Overexpression of genes selected from the neurogenic modules enhanced the production of neurons from Mll1-deleted cells, and overexpression of Brn4 (Pou3f4) in nonneurogenic cortical astroglia induced their transdifferentiation into electrophysiologically active neurons.ConclusionOur results demonstrate that Mll1 is required for the expression of neurogenic but not gliogenic transcriptional modules in a multipotent NSC population and further indicate that specific Mll1-dependent genes may be useful for direct reprogramming strategies.

Ectopic expression of specific factors such as Oct4, Sox2, and Klf4 (OSK) is sufficient to reprogram somatic cells into induced pluripotent stem cells (iPSCs). In this study, we examine the paths taken by cells during the reprogramming process by following the transcriptional activation of two pluripotent miRNA clusters (mir-290 and mir-302) in individual cells in vivo and in vitro with knockin reporters. During embryonic development and embryonic stem cell differentiation, all cells sequentially expressed mir-290 and mir-302. In contrast, during OSK-induced reprogramming, cells activated the miRNA loci in a stochastic, nonordered manner. However, the addition of Sall4 to the OSK cocktail led to a consistent reverse sequence of locus activation (mir-302 then mir-290) and increased reprogramming efficiency. These results demonstrate that cells can follow multiple paths during the late stages of reprogramming, and that the trajectory of any individual cell is strongly influenced by the combination of factors introduced.

Autosomal dominant mutations of the RNA/DNA binding protein FUS are linked to familial amyotrophic lateral sclerosis (FALS); however, it is not clear how FUS mutations cause neurodegeneration. Using transgenic mice expressing a common FALS-associated FUS mutation (FUS-R521C mice), we found that mutant FUS proteins formed a stable complex with WT FUS proteins and interfered with the normal interactions between FUS and histone deacetylase 1 (HDAC1). Consequently, FUS-R521C mice exhibited evidence of DNA damage as well as profound dendritic and synaptic phenotypes in brain and spinal cord. To provide insights into these defects, we screened neural genes for nucleotide oxidation and identified brain-derived neurotrophic factor (Bdnf) as a target of FUS-R521C-associated DNA damage and RNA splicing defects in mice. Compared with WT FUS, mutant FUS-R521C proteins formed a more stable complex with Bdnf RNA in electrophoretic mobility shift assays. Stabilization of the FUS/Bdnf RNA complex contributed to Bdnf splicing defects and impaired BDNF signaling through receptor TrkB. Exogenous BDNF only partially restored dendrite phenotype in FUS-R521C neurons, suggesting that BDNF-independent mechanisms may contribute to the defects in these neurons. Indeed, RNA-seq analyses of FUS-R521C spinal cords revealed additional transcription and splicing defects in genes that regulate dendritic growth and synaptic functions. Together, our results provide insight into how gain-of-function FUS mutations affect critical neuronal functions.

Developmental regulation of gliogenesis in the mammalian CNS is incompletely understood, in part due to a limited repertoire of lineage-specific genes. We used Aldh1l1-GFP as a marker for gliogenic radial glia and later-stage precursors of developing astrocytes and performed gene expression profiling of these cells. We then used this dataset to identify candidate transcription factors that may serve as glial markers or regulators of glial fate. Our analysis generated a database of developmental stage-related markers of Aldh1l1+ cells between murine embryonic day 13.5-18.5. Using these data we identify the bZIP transcription factor Nfe2l1 and demonstrate that it promotes glial fate under direct Sox9 regulatory control. Thus, this dataset represents a resource for identifying novel regulators of glial development.

Developmental regulation of gliogenesis in the mammalian CNS is incompletely understood, in part due to a limited repertoire of lineage-specific genes. We used Aldh1l1-GFP as a marker for gliogenic radial glia and later-stage precursors of developing astrocytes and performed gene expression profiling of these cells. We then used this dataset to identify candidate transcription factors that may serve as glial markers or regulators of glial fate. Our analysis generated a database of developmental stage-related markers of Aldh1l1+ cells between murine embryonic day 13.5-18.5. Using these data we identify the bZIP transcription factor Nfe2l1 and demonstrate that it promotes glial fate under direct Sox9 regulatory control. Thus, this dataset represents a resource for identifying novel regulators of glial development.

Long noncoding RNAs (lncRNAs) have been described in cell lines and various whole tissues, but lncRNA analysis of development in vivo is limited. Here, we comprehensively analyze lncRNA expression for the adult mouse subventricular zone neural stem cell lineage. We utilize complementary genome-wide techniques including RNA-seq, RNA CaptureSeq, and ChIP-seq to associate specific lncRNAs with neural cell types, developmental processes, and human disease states. By integrating data from chromatin state maps, custom microarrays, and FACS purification of the subventricular zone lineage, we stringently identify lncRNAs with potential roles in adult neurogenesis. shRNA-mediated knockdown of two such lncRNAs, Six3os and Dlx1as, indicate roles for lncRNAs in the glial-neuronal lineage specification of multipotent adult stem cells. Our data and workflow thus provide a uniquely coherent in vivo lncRNA analysis and form the foundation of a user-friendly online resource for the study of lncRNAs in development and disease.

In many applications, one is interested in determining which of the properties of a network module change across conditions. For example, to validate the existence of a module, it is desirable to show that it is reproducible (or preserved) in an independent test network. Here we study several types of network preservation statistics that do not require a module assignment in the test network. We distinguish network preservation statistics by the type of the underlying network. Some preservation statistics are defined for a general network (defined by an adjacency matrix) while others are only defined for a correlation network (constructed on the basis of pairwise correlations between numeric variables). Our applications show that the correlation structure facilitates the definition of particularly powerful module preservation statistics. We illustrate that evaluating module preservation is in general different from evaluating cluster preservation. We find that it is advantageous to aggregate multiple preservation statistics into summary preservation statistics. We illustrate the use of these methods in six gene co-expression network applications including 1) preservation of cholesterol biosynthesis pathway in mouse tissues, 2) comparison of human and chimpanzee brain networks, 3) preservation of selected KEGG pathways between human and chimpanzee brain networks, 4) sex differences in human cortical networks, 5) sex differences in mouse liver networks. While we find no evidence for sex specific modules in human cortical networks, we find that several human cortical modules are less preserved in chimpanzees. In particular, apoptosis genes are differentially co-expressed between humans and chimpanzees. Our simulation studies and applications show that module preservation statistics are useful for studying differences between the modular structure of networks. Data, R software and accompanying tutorials can be downloaded from the following webpage: http://www.genetics.ucla.edu/labs/horvath/CoexpressionNetwork/ModulePreservation.

Genome-wide expression profiling has aided the understanding of the molecular basis of neuronal diversity, but achieving broad functional insight remains a considerable challenge. Here, we perform the first systems-level analysis of microarray data from single neuronal populations using weighted gene co-expression network analysis to examine how neuronal transcriptome organization relates to neuronal function and diversity. We systematically validate network predictions using published proteomic and genomic data. Several network modules of co-expressed genes correspond to interneuron development programs, in which the hub genes are known to be critical for interneuron specification. Other co-expression modules relate to fundamental cellular functions, such as energy production, firing rate, trafficking, and synapses, suggesting that fundamental aspects of neuronal diversity are produced by quantitative variation in basic metabolic processes. We identify two transcriptionally distinct mitochondrial modules and demonstrate that one corresponds to mitochondria enriched in neuronal processes and synapses, whereas the other represents a population restricted to the soma. Finally, we show that galectin-1 is a new interneuron marker, and we validate network predictions in vivo using Rgs4 and Dlx1/2 knockout mice. These analyses provide a basis for understanding how specific aspects of neuronal phenotypic diversity are organized at the transcriptional level.

A mobile whole-body exposure system was developed for exposing mice to concentrated ambient particulate matter smaller than 2.5 microm in mass median aerodynamic diameter (MMAD). Each 20-L exposure cage was designed to hold 9 mice within individual compartments. This allowed for transport and subsequent exposure. Airflow mixing and the potential for stagnant areas within the compartments were modeled using computational fluid dynamic modeling (CFD). CFD analysis showed no stagnant areas and good mixing throughout the exposure cage. The actual performance of the exposure system was determined for 0.5 to 2.0 microm diameter aerosols by measuring (1) uniformity of aerosol distribution and (2) particle deposition in the tracheobronchial and pulmonary regions of mice exposed in the system. A 0.6-microm MMAD (GSD=2.0) cigarette smoke aerosol was used to experimentally measure the uniformity of aerosol distribution to the nine individual compartments. The average data from three runs showed no statistically significant difference among individual compartments. Particle deposition efficiency in adult male BALB/c mice was measured after exposure (30 min) in the system using monodisperse fluorescent polystyrene latex particles (0.5, 1, and 2 microm aerodynamic diameter). The measured deposition efficiency in this mobile exposure system for the combined tracheobronchial and pulmonary regions of the adult male BALBc mice was 21% for 0.5 microm, 11% for 1.0 microm, and 6.5% for 2.0 microm particles. These deposition efficiencies are similar to those reported for mice exposed in a nose-only exposure system, which indicates that particle losses to animal fur and exposure system surfaces were acceptable.

Strain- and variety-related differences in responses of mice have been reported for a variety of inhaled particulate and gaseous materials. It is important to understand the potential contributions to such responses of differences in delivered doses to the respiratory tract as well as differences in biochemical processes. Deposition doses of inhaled particles are influenced by several factors, including airway anatomy, ventilation, and particle characteristics. Tracheobronchial airway morphometry for airway generations 1-6 of the BALB/c mouse was generated using replica lung casts prepared in situ. Measurements were performed on two groups: control and ovalbumin-sensitized male BALB/c mice. These measurements were compared with previously published airway morphometry of male B6C3F(1) mice. Sensitization did not significantly change measured airway dimensions in the BALB/c mouse. However, the two mouse varieties had significant differences in airway anatomy. The differences found in airway anatomy between mouse varieties correlated with differences in body length and chest circumference. Particle deposition predictions for both varieties of mice were performed for unit density spherical particles from 0.1 to 10 microm in diameter at two ventilation rates using a published aerosol dosimetry computer code. Particle deposition in the proximal tracheobronchial tree ranged up to 3 times greater for the BALB/c mouse for a 2 microm particle diameter and high ventilation rate. These differences in predicted particle deposition suggest that observed strain and variety differences in response to inhaled particulate matter may be in part due to differences in delivered doses to the respiratory tract.

Introduction: For in vivo inhalation studies, aerosol dosimetry links aerosol exposure and deposited dose within the respiratory tract. Aerosol dosimetry programs like the Multiple Path Particle Deposition model utilize respiratory tract geometry, respiratory physiology, and aerosol properties to predict particle deposition within the respiratory tract. A challenge to wider use of these dosimetry programs for in vivo inhalation studies is the lack of species-specific or strain specific respiratory tract anatomy, and in some cases, strain specific respiratory physiology data. The objective of this work was to develop aerosol dosimetry predictions for the in vivo human disease models of chronic obstructive pulmonary disease (COPD; C57BL/6 mice) cardiovascular disease (CVD; ApoE-/- mice), and lung cancer (AJ mice) using the Multiple Path Particle Deposition dosimetry model. Methods: Microcomputed tomography derived tracheobronchial geometry data were combined with available pulmonary geometry data for C57BL/6, ApoE-/-, and AJ mice and incorporated into the Multiple Path Particle Deposition dosimetry model. Mouse strain specific respiratory physiology literature values were used as input into the Multiple Path Particle Deposition dosimetry model. Results: The resulting particle deposition predictions compared well with the very limited strain specific experimental particle deposition data. Since multiple tracheobronchial geometries and thus pulmonary anatomies were used for C57BL/6 and ApoE-/- mice, an estimate of intrastrain variability in predicted particle deposition was obtained. Discussion and Conclusions: The intrastrain variability in predicted particle deposition for C57BL/6 and ApoE-/- mice was always smaller in the tracheobronchial compared to pulmonary airways. The differences in reported respiratory physiology values for C57BL/6 mice resulted in greater intrastrain variability in predicted particle deposition than observed with the different tracheobronchial geometries and pulmonary anatomies. These mouse strain specific aerosol dosimetry predictions can provide insight into the delivered dose to specific respiratory tract regions that can be correlated with in vivo endpoints. [ABSTRACT FROM AUTHOR]

We compared early biological changes in mice after inhalation exposures to cigarette smoke or e-vapor aerosols (MarkTen® cartridge with Carrier, Test-1, or Test-2 formulations; 4% nicotine). Female C57BL/6 mice were exposed to 3R4F cigarette smoke or e-vapor aerosols by nose-only inhalation for up to 4 hours/day, 5 days/week, for 3 weeks. The 3R4F and e-vapor exposures were set to match the target nose port aerosol nicotine concentration (∼41 µg/L). Only the 3R4F group showed postexposure clinical signs such as tremors and lethargy. At necropsy, the 3R4F group had significant increases in lung weight and changes in bronchoalveolar lavage parameters, as well as microscopic findings in the respiratory tract. The e-vapor groups had minimal microscopic changes, including squamous metaplasia in laryngeal epiglottis, and histiocytic infiltrates in the lung (Test-2 group only). The 3R4F group had a higher incidence and severity of microscopic findings compared to any e-vapor group. Transcriptomic analysis also showed that the 3R4F group had the highest number of differentially expressed genes compared to Sham Control. Among e-vapor groups, Test-2 group had more differentially expressed genes but the magnitude of gene expression-based network perturbations in all e-vapor groups was ∼94% less than the 3R4F group. On proteome analysis in the lung, differentially regulated proteins were detected in the 3R4F group only. In conclusion, 3-weeks of 3R4F exposure induced molecular and microscopic changes associated with smoking-related diseases in the respiratory tract, while e-vapor exposures showed substantially reduced biological activities. [ABSTRACT FROM AUTHOR]

The goal of this study was to test the following hypotheses: (1) exposure to mobile emissions from mobile sources close to a heavily trafficked roadway will exacerbate airway inflammation and allergic airway responses in a sensitized mouse model, and (2) the magnitude of allergic airway disease responses will decrease with increasing distance from the roadway. A particle concentrator and a mobile exposure facility were used to expose ovalbumin (OVA)-sensitized BALB/c mice to purified air and concentrated fine and concentrated ultrafine ambient particles at 50 m and 150 m downwind from a roadway that was heavily impacted by emissions from heavy duty diesel-powered vehicles. After exposure, we assessed interleukin (IL)-5, IL-13, OVA-specific immunoglobulin E, OVA-specific immunoglobulin G1, and eosinophil influx as biomarkers of allergic responses and numbers of polymorphonuclear leukocytes as a marker of inflammation. The study was performed over a two-year period, and there were differences in the concentrations and compositions of ambient particulate matter across those years that could have influenced our results. However, averaged over the two-year period, exposure to concentrated ambient particles (CAPs) increased the biomarkers associated with airway allergies (IL-5, immunoglobulin E, immunoglobulin G1 and eosinophils). In addition, mice exposed to CAPs 50 m downwind of the roadway had, on the average, greater allergic responses and showed greater indications of inflammation than did mice exposed to CAPs 150m downwind. This study is consistent with the hypothesis that exposure to CAPs close to a heavily trafficked roadway influenced allergic airway responses. [ABSTRACT FROM AUTHOR]