Pulmonary exposure to multiwalled carbon nanotubes (MWCNTs) causes indirect systemic inflammation through unknown pathways. MWCNTs translocate only minimally from the lungs into the systemic circulation, suggesting that extrapulmonary toxicity may be caused indirectly by lung-derived factors entering the circulation. To assess a role for MWCNT-induced circulating factors in driving neuroinflammatory outcomes, mice were acutely exposed to MWCNTs (10 or 40 μg/mouse) via oropharyngeal aspiration. At 4 h after MWCNT exposure, broad disruption of the blood-brain barrier (BBB) was observed across the capillary bed with the small molecule fluorescein, concomitant with reactive astrocytosis. However, pronounced BBB permeation was noted, with frank albumin leakage around larger vessels (>10 μm), overlain by a dose-dependent astroglial scar-like formation and recruitment of phagocytic microglia. As affirmed by elevated inflammatory marker transcription, MWCNT-induced BBB disruption and neuroinflammation were abrogated by pretreatment with the rho kinase inhibitor fasudil. Serum from MWCNT-exposed mice induced expression of adhesion molecules in primary murine cerebrovascular endothelial cells and, in a wound-healing in vitro assay, impaired cell motility and cytokinesis. Serum thrombospondin-1 level was significantly increased after MWCNT exposure, and mice lacking the endogenous receptor CD36 were protected from the neuroinflammatory and BBB permeability effects of MWCNTs. In conclusion, acute pulmonary exposure to MWCNTs causes neuroinflammatory responses that are dependent on the disruption of BBB integrity.nanoparticle | blood-brain barrier | microglia | thrombospondin-1 | multiwalled carbon nanotube

The role of environmental stressors, particularly exposure to air pollution, in the development of neurodegenerative disease remains underappreciated. We examined the neurological effects of acute ozone (O3) exposure in aged mice, where increased blood-brain barrier (BBB) permeability may confer vulnerability to neuroinflammatory outcomes. C57BL/6 male mice, aged 8-10 weeks or 12-18 months were exposed to either filtered air or 1.0 ppm O3 for 4 h; animals received a single IP injection of sodium fluorescein (FSCN) 20 h postexposure. One-hour post-FSCN injection, animals were transcardially perfused for immunohistochemical analysis of BBB permeability. β-amyloid protein expression was assessed via ELISA. Flow cytometric characterization of infiltrating immune cells, including neutrophils, macrophages, and microglia populations was performed 20 h post-O3 exposure. Flow cytometry analysis of brains revealed increased microglia "activation" and presentation of CD11b, F4/80, and MHCII in aged animals relative to younger ones; these age-induced differences were potentiated by acute O3 exposure. Cortical and limbic regions in aged brains had increased reactive microgliosis and β-amyloid protein expression after O3 insult. The aged cerebellum was particularly vulnerable to acute O3 exposure with increased populations of infiltrating neutrophils, peripheral macrophages/monocytes, and Ly6C+ inflammatory monocytes after insult, which were not significantly increased in the young cerebellum. O3 exposure increased the penetration of FSCN beyond the BBB, the infiltration of peripheral immune cells, and reactive gliosis of microglia. Thus, the aged BBB is vulnerable to insult and becomes highly penetrable in response to O3 exposure, leading to greater neuroinflammatory outcomes.

Background and aims Obstructive sleep apnea (OSA) is characterized by intermittent airway obstruction and systemic hypoxia during sleep, which can contribute to an increase in reactive oxygen species, vascular remodeling, vasoconstriction and ultimately cardiovascular disease. Continuous positive airway pressure (CPAP) is a clinical therapy that maintains airway patency and mitigates several symptoms of OSA. However, it is currently unknown whether CPAP therapy also reduces the overall inflammatory potential in the circulation; to address this in an unbiased manner, we applied a novel endothelial biosensor approach, the serum cumulative inflammatory potential (SCIP) assay. Methods We studied healthy controls (n=7), OSA subjects receiving no treatment, (OSA controls) (n=7) and OSA subjects receiving CPAP for 3 months (n=8). Serum was obtained from OSA subjects before and after CPAP or no treatment. A battery of quantitative and functional assays was performed to assess the serum inflammatory potential, in terms of endothelial responses. For the SCIP assay, human coronary artery endothelial cells (hCAECs) were incubated with 5% serum in media from individual subjects for 4 h. qPCR was performed to assess endothelial inflammatory transcript (ICAM-1, VCAM-1, IL-8, P-selectin, CCL5, and CXCL12) responses to serum. Additionally, transendothelial resistance was measured in serum-incubated hCAECs following leukocyte challenge. Results hCAECs exhibited significant increases in VCAM-1, ICAM-1, IL-8 and P-selectin mRNA when incubated with serum from OSA patients compared to serum from healthy control subjects. Furthermore, compared to no treatment, serum from CPAP-treated individuals was less potent at inducing inflammatory gene expression in the SCIP assay. Similarly, in a leukocyte adhesion assay, naïve cells treated with serum from patients who received CPAP exhibited improved endothelial barrier function than cells treated with OSA control serum. Conclusions OSA results in greater serum inflammatory potential, thereby driving endothelial activation and dysfunction.

BackgroundDeleterious consequences of exposure to traffic emissions may derive from interactions between carbonaceous particulate matter (PM) and gaseous components in a manner that is dependent on the surface area or complexity of the particles. To determine the validity of this hypothesis, we examined pulmonary and neurological inflammatory outcomes in C57BL/6 and apolipoprotein E knockout (ApoE−/−) male mice after acute and chronic exposure to vehicle engine-derived particulate matter, generated as ultrafine (UFP) and fine (FP) sizes, with additional exposures using UFP or FP combined with gaseous copollutants derived from fresh gasoline and diesel emissions, labeled as UFP + G and FP + G.ResultsThe UFP and UFP + G exposure groups resulted in the most profound pulmonary and neuroinflammatory effects. Phagocytosis of UFP + G particles via resident alveolar macrophages was substantial in both mouse strains, particularly after chronic exposure, with concurrent increased proinflammatory cytokine expression of CXCL1 and TNFα in the bronchial lavage fluid. In the acute exposure paradigm, only UFP and UFP + G induced significant changes in pulmonary inflammation and only in the ApoE−/− animals. Similarly, acute exposure to UFP and UFP + G increased the expression of several cytokines in the hippocampus of ApoE−/− mice including Il-1β, IL-6, Tgf-β and Tnf-α and in the hippocampus of C57BL/6 mice including Ccl5, Cxcl1, Il-1β, and Tnf-α. Interestingly, Il-6 and Tgf-β expression were decreased in the C57BL/6 hippocampus after acute exposure. Chronic exposure to UFP + G increased expression of Ccl5, Cxcl1, Il-6, and Tgf-β in the ApoE−/− hippocampus, but this effect was minimal in the C57BL/6 mice, suggesting compensatory mechanisms to manage neuroinflammation in this strain.ConclusionsInflammatory responses the lung and brain were most substantial in ApoE−/− animals exposed to UFP + G, suggesting that the surface area-dependent interaction of gases and particles is an important determinant of toxic responses. As such, freshly generated UFP, in the presence of combustion-derived gas phase pollutants, may be a greater health hazard than would be predicted from PM concentration, alone, lending support for epidemiological findings of adverse neurological outcomes associated with roadway proximity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-016-0177-x) contains supplementary material, which is available to authorized users.

Exposure to windblown particulate matter (PM) arising from legacy uranium (U) mine sites in the Navajo Nation may pose a human health hazard due to their potentially high metal content, including U and vanadium (V). To assess the toxic impact of PM derived from Claim 28 (a priority U mine) compared with background PM, and consider the putative role of metal species U and V. Two representative sediment samples from Navajo Nation sites (Background PM and Claim 28 PM) were obtained, characterized in terms of chemistry and morphology, and fractioned to the respirable (≤ 10 μm) fraction. Mice were dosed with either PM sample, uranyl acetate, or vanadyl sulfate via aspiration (100 µg), with assessments of pulmonary and vascular toxicity 24 h later. Particulate matter samples were also examined for in vitro effects on cytotoxicity, oxidative stress, phagocytosis, and inflammasome induction. Claim 28 PM10 was highly enriched with U and V and exhibited a unique nanoparticle ultrastructure compared with background PM10. Claim 28 PM10 exhibited enhanced pulmonary and vascular toxicity relative to background PM10. Both U and V exhibited complementary pulmonary inflammatory potential, with U driving a classical inflammatory cytokine profile (elevated interleukin [IL]-1β, tumor necrosis factor-α, and keratinocyte chemoattractant/human growth-regulated oncogene) while V preferentially induced a different cytokine pattern (elevated IL-5, IL-6, and IL-10). Claim 28 PM10 was more potent than background PM10 in terms of in vitro cytotoxicity, impairment of phagocytosis, and oxidative stress responses. Resuspended PM10 derived from U mine waste exhibit greater cardiopulmonary toxicity than background dusts. Rigorous exposure assessment is needed to gauge the regional health risks imparted by these unremediated sites.

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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/m 3 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.

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