Asian sand dust enhances ovalbumin-induced eosinophil recruitment in the alveoli and airway of mice

Acceleration of acute lung inflammation by IL-1α released through cell death of alveolar macrophages upon phagocytosis of fine Asian sand dust particles

Asian sand dust (ASD), a significant desert sand dust, contains sub-2.5 µm fine particles and adversely affects human health, particularly exacerbating respiratory diseases. Despite this, the intricate physiological responses triggered by inhaled ASD particles remain incompletely understood. This study aimed to comprehensively examine the respiratory effects of ASD, focusing on the spatial distribution of inhaled ASD fine particles within the lungs and the immediate physiological responses they incite. Intratracheal administration of ASD fine particles in mice resulted in efficient phagocytosis by alveolar macrophages (AMs), leading to subsequent neutrophilic inflammation. A subset of ASD-phagocytosed AMs underwent necroptosis, releasing interleukin-1α (IL-1α), causing an increase in chemokines and neutrophils. These responses occurred rapidly within hours of exposure, with endotoxin in ASD particles contributing to the process. Despite variations in desert sand dust composition based on collection locale and timing, this study's findings provide a foundational basis for understanding the biological effects of desert sand dust. Insights gained into the biological responses to desert sand dust hold promise for developing preventive measures such as air purifiers, and therapeutic agents such as IL-1α neutralizing antibodies, antibacterial agents and cell death inhibitors for human diseases associated with such environmental exposures.

The influence of long-range transported Saharan dust on the inflammatory potency of ambient PM2.5 and PM10

Although desert dust promotes morbidity and mortality, it is exempt from regulations. Its health effects have been related to its inflammatory properties, which can vary between source regions. It remains unclear which constituents cause this variability. Moreover, whether long-range transported desert dust potentiates the hazardousness of local particulate matter (PM) is still unresolved. We aimed to assess the influence of long-range transported desert dust on the inflammatory potency of PM2.5 and PM10 collected in Cape Verde and to examine associated constituents. During a reference period and two Saharan dust events, 63 PM2.5 and PM10 samples were collected at four sampling stations. The content of water-soluble ions, elements, and organic and elemental carbon was measured in all samples and endotoxins in PM10 samples. The PM-induced release of inflammatory cytokines from differentiated THP-1 macrophages was evaluated. The association of interleukin (IL)-1β release with PM composition was assessed using principal component (PC) regressions. PM2.5 from both dust events and PM10 from one event caused higher IL-1β release than PM from the reference period. PC regressions indicated an inverse relation of IL-1β release with sea spray ions in both size fractions and organic and elemental carbon in PM2.5. The PC with the higher regression coefficient suggested that iron and manganese may contribute to PM2.5-induced IL-1β release. Only during the reference period, endotoxin content strongly differed between sampling stations and correlated with inflammatory potency. Our results demonstrate that long-range transported desert dust amplifies the hazardousness of local air pollution and suggest that, in PM2.5, iron and manganese may be important. Our data indicate that endotoxins are contained in local and long-range transported PM10 but only explain the variability in inflammatory potency of local PM10. The increasing inflammatory potency of respirable and inhalable PM from desert dust events warrants regulatory measures and risk mitigation strategies.

Dithiothreitol-Measured Oxidative Potential of Reference Materials of Mineral Dust: Implications for the Toxicity of Mineral Dust Aerosols in the Atmosphere

Oxidative stress is a mechanism that might raise the toxicity of mineral dust aerosols. We evaluated the oxidative potential (OP) of four reference materials (RMs) of mineral dusts using dithiothreitol assay. The OP of the water-soluble fraction of the dust RMs accounts for 40%-70% of the OP of the total fraction. The values of total and water-soluble OP normalized by the surface area of insoluble particles showed agreement among the different dust RMs. The surface area of insoluble dust particles was therefore inferred as an important factor affecting the OP of mineral dust. Using the relation between total OP and the surface area of insoluble particles of the dust RMs, we estimated the total OPs of fine and coarse atmospheric mineral dust aerosols assuming a typical particle size distribution of Asian dust aerosols observed in Japan. Mass-normalized total OPs were estimated at 44 and 23 pmol min-1 μg-1 for fine and coarse atmospheric mineral dust particles. They closely approximate the values observed for urban aerosols in Japan, which suggests that mineral dust plume advection can lead to a marked increase in human exposure to redox-active aerosols, even far downwind from mineral dust source regions.

Inhalable Saharan dust induces oxidative stress, NLRP3 inflammasome activation, and inflammatory cytokine release

Desert dust is increasingly recognized as a major air pollutant affecting respiratory health. Since desert dust exposure cannot be regulated, the hazardousness of its components must be understood to enable health risk mitigation strategies. Saharan dust (SD) comprises about half of the global desert dust and contains quartz, a toxic mineral dust that is known to cause severe lung diseases via oxidative stress and activation of the NLRP3 inflammasome-interleukin-1β pathway. We aimed to assess the physicochemical and microbial characteristics of SD responsible for toxic effects. Also, we studied the oxidative and pro-inflammatory potential of SD in alveolar epithelial cells and the activation of the NLRP3 inflammasome in macrophage-like cells in comparison to quartz dusts and synthetic amorphous silica (SAS). Characterization revealed that SD contained Fe, Al, trace metals, sulfate, diatomaceous earth, and endotoxin and had the capacity to generate hydroxyl radicals. We exposed A549 lung epithelial cells and wild-type and NLRP3^-/- THP-1 macrophage-like cells to SD, three well-investigated quartz dusts, and SAS. SD induced oxidative stress in A549 cells after 24 h more potently than the quartz dusts. The quartz dusts and SAS upregulated interleukin 8 expression after 4 h and 24 h while SD only caused a transient upregulation. SD, the quartz dusts, and SAS induced interleukin-1β release from wild-type THP-1 cells>20-fold stronger than from NLRP3^-/- THP-1 cells. Interleukin-1β release was lower for SD, in which microbial components including endotoxin were heat-destructed. In conclusion, microbial components in SD are pivotal for its toxicity. In the epithelium, the effects of SD contrasted with crystalline and amorphous silica in terms of potency and persistence. In macrophages, the strong involvement of the NLRP3 inflammasome emphasizes the acute and chronic health risks associated with desert dust exposure.

Mechanisms underlying the health effects of desert sand dust

Desertification and climate change indicate a future expansion of the global area of dry land and an increase in the risk of drought. Humans may therefore be at an ever-increasing risk of frequent exposure to, and resultant adverse health effects of desert sand dust. This review appraises a total of 52 experimental studies that have sought to identify mechanisms and intermediate endpoints underlying epidemiological evidence of an impact of desert dust on cardiovascular and respiratory health. Toxicological studies, in main using doses that reflect or at least approach real world exposures during a dust event, have demonstrated that virgin sand dust particles and dust storm particles sampled at remote locations away from the source induce inflammatory lung injury and aggravate allergen-induced nasal and pulmonary eosinophilia. Effects are orchestrated by cytokines, chemokines and antigen-specific immunoglobulin potentially via toll-like receptor/myeloid differentiation factor signaling pathways. Findings suggest that in addition to involvement of adhered chemical and biological pollutants, mineralogical components may also be implicated in the pathogenesis of human respiratory disorders during a dust event. Whilst comparisons with urban particulate matter less than 2.5 μm in diameter (PM2.5) suggest that allergic inflammatory responses are greater for microbial element-rich dust- PM2.5, aerosols generated during dust events appear to have a lower oxidative potential compared to combustion-generated PM2.5 sampled during non-dust periods. In vitro findings suggest that the significant amounts of suspended desert dust during storm periods may provide a platform to intermix with chemicals on its surfaces, thereby increasing the bioreactivity of PM2.5 during dust storm episodes, and that mineral dust surface reactions are an unrecognized source of toxic organic chemicals in the atmosphere, enhancing toxicity of aerosols in urban environments. In summary, the experimental research on desert dust on respiratory endpoints go some way in clarifying the mechanistic effects of atmospheric desert dust on the upper and lower human respiratory system. In doing so, they provide support for biological plausibility of epidemiological associations between this particulate air pollutant and events including exacerbation of asthma, hospitalization for respiratory infections and seasonal allergic rhinitis.

Latent 1,3-β-D-glucan acts as an adjuvant for allergen-specific IgE production induced by Japanese cedar pollen exposure

BACKGROUND

The pollen grains of several plant species contain 1,3-β-D-glucan (BG). BG activates dendritic cells (DCs) and subsequently regulates the innate immune responses. Within Japan, the most common disease associated with type-I hypersensitivity is Japanese cedar pollinosis. However, the role of BG in Japanese cedar pollen (JCP) remains unclear. This study examined the localization and immunological effects of BG in JCP.

METHODS

The localization of BG in JCP grain was determined by immunohistochemical staining using a soluble dectin-1 protein probe and a BG recognition protein (BGRP). The content of BG extracted from JCP was measured by a BGRP-based ELISA-like assay. The cytokine production by bone marrow-derived DCs (BMDCs) obtained from wild-type and BG receptor (dectin-1) knock-out mice was examined in vitro. The mice were intranasally administered JCP grains and the specific serum Ig levels were then quantified.

RESULTS

BG was detected in the exine and cell wall of the generative cell and tube cell of the JCP grain. Moreover, BG in the exine stimulated production of TNF-α and IL-6 in the BMDCs via a dectin-1-dependent mechanism. Meanwhile, JCP-specific IgE and IgG were detected in the serum of wild-type mice that had been intranasally administered with JCP grains. These mice also exhibited significantly enhanced sneezing behavior. However, dectin-1 knock-out mice exhibited significantly lower JCP-specific IgE and IgG levels compared to wild-type mice.

CONCLUSIONS

Latent BG in JCP can act as an adjuvant to induce JCP-specific antibody production via dectin-1.

In vivo immune activation of splenocytes following exposure to tar from Asian sand dust

Air pollution, especially that initiated by particulate matter (PM), has been implicated as a risk factor for several inflammatory diseases. Previously, it was reported that PM enhances immune responses. PM includes the tar fraction that contains polycyclic aromatic hydrocarbons (PAHs), which produce adverse health effects in exposed individuals. However, the influence of the tar fraction (as a component of PM) on splenocytes is not fully understood. The aim of this study was to determine the effects of the tar fraction extracted from PM collected from the atmosphere in Fukuoka, Japan, on mouse splenocytes. ICR mice were administered tar (1 or 5 μg/mouse) intratracheally 4 times at 2-week intervals, and splenocytes from the tar-treated mice were extracted and examined. The parameters determined were proliferation, cytokine concentrations and transcription factors activation. Following tar treatment, splenocyte proliferation increased relative to controls. Concanavalin A (ConA)-induced interleukin (IL)-2 formation and ConA- or lipopolysaccharide (LPS)-induced interferon-γ production were elevated in splenocytes from tar-exposed mice. However, the production of tumor necrosis factor-α and IL-6 induced by LPS was not markedly changed following tar treatment. Further, nuclear factor of activated T cells, but not nuclear factor-κB, was enhanced in splenocytes of tar-exposed mice. Data indicate that tar-activated splenocytes and PM-bound PAHs might contribute to T cell activation in the spleen.

Global nature of airborne particle toxicity and health effects: a focus on megacities, wildfires, dust storms and residential biomass burning

Since air pollutants are difficult and expensive to control, a strong scientific underpinning to policies is needed to guide mitigation aimed at reducing the current burden on public health. Much of the evidence concerning hazard identification and risk quantification related to air pollution comes from epidemiological studies. This must be reinforced with mechanistic confirmation to infer causality. In this review we focus on data generated from four contrasting sources of particulate air pollution that result in high population exposures and thus where there remains an unmet need to protect health: urban air pollution in developing megacities, household biomass combustion, wildfires and desert dust storms. Taking each in turn, appropriate measures to protect populations will involve advocating smart cities and addressing economic and behavioural barriers to sustained adoption of clean stoves and fuels. Like all natural hazards, wildfires and dust storms are a feature of the landscape that cannot be removed. However, many efforts from emission containment (land/fire management practices), exposure avoidance and identifying susceptible populations can be taken to prepare for air pollution episodes and ensure people are out of harm's way when conditions are life-threatening. Communities residing in areas affected by unhealthy concentrations of any airborne particles will benefit from optimum communication via public awareness campaigns, designed to empower people to modify behaviour in a way that improves their health as well as the quality of the air they breathe.

Health Effects of Asian Dust: A Systematic Review and Meta-Analysis

BACKGROUND

Potential adverse health effects of Asian dust exposure have been reported, but systematic reviews and quantitative syntheses are lacking.

OBJECTIVE

We reviewed epidemiologic studies that assessed the risk of mortality, hospital admissions, and symptoms/dysfunction associated with exposure to Asian dust.

METHODS

We performed a systematic search of PubMed and Web of Science to identify studies that reported the association between Asian dust exposure and human health outcomes. We conducted separate meta-analyses using a random-effects model for mortality and hospital admissions for a specific health outcome and assessed pooled estimates for each lag when at least three studies were available for a specific lag.

RESULTS

We identified 89 studies that met our inclusion criteria for the systematic review, and 21 studies were included in the meta-analysis. The pooled estimates (percentage changes) of mortality from circulatory and respiratory causes for Asian dust days vs. non-Asian dust days were 2.33% [95% confidence interval (CI): 0.76, 3.93] increase at lag 0 and 3.99% (95% CI: 0.08, 8.06) increase at lag 3, respectively. The increased risk for hospital admissions for respiratory disease, asthma, and pneumonia peaked at lag 3 by 8.85% (95% CI: 0.80, 17.55), 14.55% (95% CI: 6.74, 22.94), and 8.51% (95% CI: 2.89, 14.44), respectively. Seven of 12 studies reported reduced peak expiratory flow, and 16 of 21 studies reported increased respiratory symptoms associated with Asian dust exposure. There were substantial variations between the studies in definitions of Asian dust, study designs, model specifications, and confounder controls.

DISCUSSION

We found evidence of increased mortality and hospital admissions for circulatory and respiratory events. However, the number of studies included in the meta-analysis was not large and further evidences are merited to strengthen our conclusions. Standardized protocols for epidemiological studies would facilitate interstudy comparisons. https://doi.org/10.1289/EHP5312.

Ambient fine and coarse particles in Japan affect nasal and bronchial epithelial cells differently and elicit varying immune response

Ambient particulate matter (PM) epidemiologically exacerbates respiratory and immune health, including allergic rhinitis (AR) and bronchial asthma (BA). Although fine and coarse particles can affect respiratory tract, the differences in their effects on the upper and lower respiratory tract and immune system, their underlying mechanism, and the components responsible for the adverse health effects have not been yet completely elucidated. In this study, ambient fine and coarse particles were collected at three different locations in Japan by cyclone technique. Both particles collected at all locations decreased the viability of nasal epithelial cells and antigen presenting cells (APCs), increased the production of IL-6, IL-8, and IL-1β from bronchial epithelial cells and APCs, and induced expression of dendritic and epithelial cell (DEC) 205 on APCs. Differences in inflammatory responses, but not in cytotoxicity, were shown between both particles, and among three locations. Some components such as Ti, Co, Zn, Pb, As, OC (organic carbon) and EC (elemental carbon) showed significant correlations to inflammatory responses or cytotoxicity. These results suggest that ambient fine and coarse particles differently affect nasal and bronchial epithelial cells and immune response, which may depend on particles size diameter, chemical composition and source related particles types.

The toll like receptor 4-myeloid differentiation factor 88 pathway is essential for particulate matter-induced activation of CD4-positive cells

Asian sand dust (ASD), a type of particulate matter (PM) found in Asia, can be transported to East Asia. We recently found that acute splenic inflammation is induced by ASD in mouse models. In this study, we examined the effect of sub-chronic ASD exposure on mouse immune cells. Mice were intratracheally administered ASD once every 2 weeks for 8 weeks and killed 24 hours after the final administration. Wild-type (WT) mice showed increased cell viability after ASD administration. In contrast, ASD administration induced splenocyte activation in toll-like receptor (TLR)2^-/- , but not TLR4^-/- mice. Furthermore, concanavalin A-induced interleukin-2 production increased after ASD administration in WT and TLR2^-/- mice, but not in TLR4^-/- or myeloid differentiation factor (MyD)88^-/- mice. Immunoblotting demonstrated that nuclear factor κB (NF-κB) was activated in WT mice, but not in TLR4^-/- or MyD88^-/- mice. The NF-κB-dependent gene products CDK2 and intercellular cell adhesion molecule-1 were upregulated upon ASD administration in WT mice, but not in TLR4^-/- or MyD88^-/- mice. Furthermore, the particles themselves, rather than particle constituents, activated NF-κB in CD4-positive cells through the TLR4 or MyD88 pathway. Taken together, these results indicate that particle-induced splenic inflammation occurs via TLR4-MyD88 signaling.

Environmental pollution and allergies

Environmental changes are thought to be the main factor in the rapid increase and worsening of allergic diseases. While there have been significant changes in many environmental factors, including in environments such as residential, health and sanitation, food, and water/soil/atmospheric environments, the root of each of these changes is likely an increase in chemical substances. In fact, various environmental pollutants, such as air pollutants and chemical substances, have been shown to worsen various allergies in experimental studies. For example, diesel exhaust particles (DEPs), which are an agglomeration of particles and a wide array of chemical substances, aggravate asthma, primarily due to the principle organic chemical components of DEPs. In addition, environmental chemicals such as phthalate esters, which are commonly used as plasticizers in plastic products, also aggravate atopic dermatitis. It has also become evident that extremely small nanomaterials and Asian sand dust particles can enhance allergic inflammation. While the underlying mechanisms that cause such aggravation are becoming clearer at the cellular and molecular levels, methods to easily and quickly evaluate (screen) the ever-increasing amount of environmental pollutants for exacerbating effects on allergies are also under development. To eliminate and control allergic diseases, medical measures are necessary, but it is also essential to tackle this issue by ameliorating environmental changes.

Differences in allergic inflammatory responses in murine lungs: comparison of PM2.5 and coarse PM collected during the hazy events in a Chinese city

Urban particulate matter (PM) is associated with an increase in asthma. PM2.5 (<PM2.5 μm) and coarse PM (CPM: PM2.5-PM10 μm) were collected from the air in a Chinese city during haze events. The amounts of polycyclic aromatic hydrocarbons (PAHs) were higher in PM2.5 than in CPM. Conversely, microbial elements LPS and β-glucan were much higher in CPM than in PM2.5. Concentrations of Si, Al, Fe, and Ti in CPM were greater than in PM2.5, while Pb, Cu and As concentrations were lower than in PM2.5. When RAW264.7 cells were treated with PM2.5 and CPM, the pro-inflammatory response in the cells was associated with the microbial element levels and attenuated partly by both polymyxin B (PMB) and N-acetylcystein (NAC). The expression of the oxidative stress response gene heme oxygenase1 was associated with PAHs levels. The exacerbating effects of the two-types of PM on murine lung eosinophilia were compared to clarify the role of toxic materials. When BALB/c mice were intratracheally instilled with PM2.5 or CPM (total 0.4 mg) + ovalbumin (OVA), both exacerbated lung eosinophilia along with allergy-relevant biological indicators, such as OVA-specific IgE in serum; enhancement of lung pathology when compared with counterpart samples without OVA. The exacerbating effects were greater in microbial element-rich CPM than in organic chemical-rich PM2.5. These results indicate that microbial elements have more potently exacerbating effects on the development of lung eosinophilia than do organic chemicals. In addition, oxidative stress and transition metals might be associated with the exacerbation of this negative effect.

Gene Expression Analysis of Murine Lungs Following Pulmonary Exposure to Asian Sand Dust Particles

The respiratory health impact of Asian sand dust events originating in the deserts of China has become a concern within China and in its neighboring countries. We examined the effects of Asian sand dust particles (ASDPs) on gene expression in the murine lung using microarray analysis and elucidated the components responsible for lung inflammation. Male ICR mice were intratracheally administrated ASDPs, heat-treated ASDPs (ASDP-F, lipopolysaccaride [LPS], or β-glucan free), or kaolin particles. We performed microarray analysis for murine lungs, the results of which were confirmed by quantitative reverse transcription–polymerase chain reaction (RT-PCR). We also assessed the protein expression and histologic changes. Exposure to ASDP, ASDP-F, or kaolin upregulated (>2-fold) 112, 36, or 9 genes, respectively, compared with vehicle exposure. In particular, ASDP exposure markedly enhanced inflammatory response–related genes, including chemokine (C-X-C motif) ligand 1/keratinocyte-derived chemokine, chemokine (C-X-C motif) ligand 2/macrophage inflammatory protein-2, chemokine (C-C motif) ligand 3/macrophage inflammatory protein-1α, and chemokine (C-X-C motif) ligand 10/interferon-gamma–inducible protein-10 (>6-fold). The results were correlated with those of the quantitative RT-PCR and the protein expression analyses in overall trend. In contrast, exposure to ASDP-F attenuated the enhanced expression of these proinflammatory molecules. Kaolin exposure increased the expression of genes and proteins for the chemokines. In histopathologic changes, exposure to ASDP prominently enhanced pulmonary neutrophilic inflammation, followed by kaolin and ASDP-F exposure in the order. Taken together, exposure to ASDP causes pulmonary inflammation via the expression of proinflammatory molecules, which can be attributed to LPS and β-glucan absorbed in ASDPs. Furthermore, microarray analysis should be effective for identifying potentially novel genes, sensitive biomarkers, and pathways involved in the health effects of the exposure to environmental particles (e.g., ASDPs).

Biological factor related to Asian sand dust particles contributes to the exacerbation of asthma

Epidemiologic studies have revealed that Asian sand dust particles (ASDs) can affect respiratory and immune health represented by asthma. Factors responsible for the exacerbation of asthma remain unclear. The fungus Bjerkandera adusta (B.ad) and polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) have been identified in ASDs collected from the atmosphere when an ASD event occurred. We investigated the effects of B.ad and BaP related to ASDs on respiratory and immune systems. Bone marrow-derived antigen-presenting cells (APCs) and splenocytes from atopic prone NC/Nga mice and human airway epithelial cells were exposed to the B.ad or to BaP in the presence and absence of heated-ASDs (H-ASDs). B.ad and BaP in both the presence and absence of H-ASDs increased the expression of cell surface molecules on APCs. H-ASDs alone slightly activated APCs. The expressions induced by B.ad were higher than those induced by BaP in the presence and absence of H-ASDs. There were no remarkable effects on the activation of splenocytes or the proinflammatory responses in airway epithelial cells. These results suggest that B.ad rather than BaP contributes to the exacerbation of asthma regardless of the presence or absence of sand particles, particularly by the activation of the immune system via APCs. Copyright © 2016 John Wiley & Sons, Ltd.

Lipopolysaccharide attached to urban particulate matter 10 suppresses immune responses in splenocytes while particulate matter itself activates NF-κB

We previously reported that Asian sand dust (ASD), which contains particulate matter (PM) less than 10 μm in diameter (PM10), induced subacute inflammation in splenocytes. However, it was unclear whether the PM itself or compounds attached to its surface induced the inflammation. Here we characterized the role of organic substances adsorbed onto the PM10 surface in triggering inflammation by comparing the effect on splenocyte activation of PM10 from urban areas (urPM10), which is rich in lipopolysaccharide (LPS) as compared to ASD, with that of heated PM10 (H-PM). BALB/c mice were intratracheally administered urPM10 or H-PM with or without LPS (1 ng and 10 ng) four times at 2-week intervals, and splenocytes were prepared at 24 h after the final administration to assay the immune responses. urPM10 suppressed splenocyte activation, while H-PM activated splenocytes and LPS neutralization by polymyxin B rescued urPM10-induced immunosuppression. Co-administration of LPS with H-PM clearly suppressed mitogen-induced immune responses in the spleen. Consistent with these results, H-PM induced the phosphorylation of nuclear factor κB (NF-κB) p65 and I kappa B kinase (IKK), which was inhibited by co-administration of LPS. In mice deficient in the LPS signal transducer MyD88, splenocyte activation after LPS or H-PM treatment in vivo was comparable to that in the control. Altogether, our results indicate that PM10 itself could activate NF-κB through the MyD88 pathway, which was modulated by the amount of LPS attached.

Asian Sand Dust Enhances the Inflammatory Response and Mucin Gene Expression in the Middle Ear

Objectives.

Asia sand dust (ASD) is known to cause various human diseases including respiratory infection. The aim of this study was to examine the effect of ASD on inflammatory response in human middle ear epithelial cells (HMEECs) in vitro and in vivo.

Methods.

Cell viability was assessed using the cell counting kit-8 assay. The mRNA levels of various genes including COX-2, TNF-a, MUC 5AC, MUC 5B, TP53, BAX, BCL-2, NOX4, and SOD1 were analyzed using semiquantitative realtime polymerase chain reaction. COX-2 protein levels were determined by western blot analysis. Sprague Dawley rats were used for in vivo investigations of inflammatory reactions in the middle ear epithelium as a result of ASD injection.

Results.

We observed dose-dependent decrease in HMEEC viability. ASD exposure significantly increased COX-2, TNF-a, MUC5AC, and MUC5B mRNA expression. Also, ASD affected the mRNA levels of apoptosis- and oxidative stress-related genes. Western blot analysis revealed a dose-dependent increase in COX-2 production. Animal studies also demonstrated an ASD-induced inflammatory response in the middle ear epithelium.

Conclusion.

Environmental ASD exposure can result in the development of otitis media.

Differences in allergic inflammatory responses between urban PM2.5 and fine particle derived from desert-dust in murine lungs

The biological and chemical natures of materials adsorbed onto fine particulate matter (PM2.5) vary by origin and passage routes. The exacerbating effects of the two samples-urban PM2.5 (U-PM2.5) collected during the hazy weather in a Chinese city and fine particles (ASD-PM2.5) collected during Asian sand dust (ASD) storm event days in Japan-on murine lung eosinophilia were compared to clarify the role of toxic materials in PM2.5. The amounts of β-glucan and mineral components were higher in ASD-PM2.5 than in U-PM2.5. On the other hand, organic chemicals, including polycyclic aromatic hydrocarbons (PAHs), were higher in U-PM2.5 than in ASD-PM2.5. When BALB/c mice were intratracheally instilled with U-PM2.5 and ASD-PM2.5 (total 0.4 mg/mouse) with or without ovalbumin (OVA), various biological effects were observed, including enhancement of eosinophil recruitment induced by OVA in the submucosa of the airway, goblet cell proliferation in the bronchial epithelium, synergic increase of OVA-induced eosinophil-relevant cytokines and a chemokine in bronchoalveolar lavage fluid, and increase of serum OVA-specific IgG1 and IgE. Data demonstrate that U-PM2.5 and ASD-PM2.5 induced allergic inflammatory changes and caused lung pathology. U-PM2.5 and ASD-PM2.5 increased F4/80(+) CD11b(+) cells, indicating that an influx of inflammatory and exudative macrophages in lung tissue had occurred. The ratio of CD206 positive F4/80(+) CD11b(+) cells (M2 macrophages) in lung tissue was higher in the OVA+ASD-PM2.5 treated mice than in the OVA+U-PM2.5 treated mice. These results suggest that the lung eosinophilia exacerbated by both PM2.5 is due to activation of a Th2-associated immune response along with induced M2 macrophages and the exacerbating effect is greater in microbial element (β-glucan)-rich ASD-PM2.5 than in organic chemical-rich U-PM2.5.

PM2.5-rich dust collected from the air in Fukuoka, Kyushu, Japan, can exacerbate murine lung eosinophilia

PM2.5 can exacerbate asthma. Organic substances adsorbed on PM2.5-rich dust (PM2.5rd) were inactivated by heating at 360 °C. To characterize the role of organic substances, the effects of PM2.5rd and heated PM2.5-rich dust (H-PM2.5 rd) on allergic lung inflammation were investigated. BALB/c mice were intratracheally administered PM2.5rd or H-PM2.5rd with or without ovalbumin (OVA) four times at 2-week intervals. PM2.5rd, but not H-PM2.5rd, caused neutrophilic alveolitis and bronchitis. In the presence of OVA, PM2.5rd caused severe eosinophil infiltration and goblet cells proliferation in airways, along with a marked induction of the Th2 cytokines interleukin (IL)-4 and IL-13, and the eosinophil-related cytokine IL-5 in bronchoalveolar lavage fluid (BALF). OVA + H-PM2.5rd caused a weaker response. PM2.5rd showed adjuvant effects on OVA-specific immunoglobulin E (IgE) and IgG1 production, but H-PM2.5rd showed minimal effects. These findings suggested that PM2.5rd-bound substances might aggravate lung eosinophilia. To clarify the roles of TLR2, TLR4, and MyD88 on cytokine production in PM2.5rd, murine bone marrow-derived macrophages (BMDMs) from wild-type (WT), TLR2(-/-), TLR4(-/-), and MyD88(-/-) BALB/c mice were stimulated with dust. Cytokine production was low or undetectable in TLR4(-/-) cells, but occurred from TLR2(-/-) cells, and production by MyD88(-/-) cells was higher than by TLR4(-/-) cells. These results suggest that TLR4 and TLR2 ligands (LPS and β-glucan, respectively) mainly contributed to cytokines production induced by PM2.5rd. In addition to chemical substances, PM2.5-bound microbial substances might act in inflammatory and allergic lung diseases.

Asian sand dust causes subacute peripheral immune modification with NF-κB activation

Asian sand dust (ASD), a type of particulate matter found in Asia, migrates to East Asia. The increased airborne spread of ASD has led to concerns regarding possible adverse health effects. Our group previously reported that ASD induces lung inflammation in mice, but it is still unclear whether ASD affects lymphoid organs. In this study, we investigated the effect of ASD on splenocytes in a mouse model of ASD exposure. ICR mice were intratracheally administered a single dose of normal saline (control) or ASD and were subsequently sacrificed 1 or 3 days later. TNF-α production in bronchoalveolar lavage fluids was higher at day 1, but not at day 3, after ASD administration. The enzyme-linked immunosorbent assay results showed that ASD administration increased mitogen-induced IL-2, TNF-α, and IL-6 production in splenocytes. Additionally, cell viability assay showed enhanced splenocyte proliferation at day 3, but not at day 1, after ASD administration. The electrophoretic mobility shift assay results demonstrated that nuclear factor κB (NF-κB) was activated in splenocytes on day 3, but not on day 1. In particular, NF-κB activation was detected in CD4(+) and CD11b(+) cells on day 3. These results suggest that ASD induces subacute inflammatory responses with NF-κB activation in the spleen, in contrast to acute inflammation in the lungs.

Asian sand dust aggregate causes atopic dermatitis-like symptoms in Nc/Nga mice

Background

Asian sand dust (ASD) originates from the arid and semiarid areas of China, and epidemiologic studies have shown that ASD exposure is associated with various allergic and respiratory symptoms. However, few studies have been performed to assess the relationship between skin inflammation and ASD exposure.

Methods

Twelve-week-old NC/Nga mice were divided into 6 groups (n = 8 for each group): hydrophilic petrolatum only (control); hydrophilic petrolatum plus ASD (ASD); hydrophilic petrolatum and heat inactivated-ASD (H-ASD); Dermatophagoides farinae extract (Df); Df and ASD (Df + ASD), and; Df and H-ASD (Df + H-ASD). The NC/Nga mice in each group were subjected to treatment twice a week for 4 weeks. We evaluated skin lesions by symptoms, pathologic changes, and serum IgE levels.

Results

ASD alone did not induce atopic dermatitis (AD)-like skin symptoms. However, Df alone, Df + H-ASD and Df + ASD all induced AD-like symptoms, and dermatitis scores in the group of Df + ASD group were significantly greater than that of the Df group (P = 0.0011 at day 21; and P = 0.017 at day 28). Mean serum IgE was markedly increased in the Df and Df + ASD groups, compared to the ASD and control groups (P < 0.0001), and serum IgE levels in the Df + ASD group were significantly higher compared to the Df group (P = 0.003).

Conclusions

ASD alone did not cause AD-like symptoms in NC/Nga mice. However, AD-like symptoms induced by Df, a major allergen, were enhanced by adding ASD. Although no epidemiological studies have been conducted for the association between ASD and symptoms of dermatitis, our data suggest that it is likely that ASD may contribute to the exacerbation of not only respiratory symptoms, but also skin diseases, in susceptible individuals.

Effects of Long-Term Dust Exposure on Human Respiratory System Health in Minqin County, China

The aim of this study was to assess the effects of long-term sand dust exposure on human respiratory health. Dust events break out frequently in Minqin County, northwest China, whereas Pingliang City, northwest China, is rarely influenced by dust events. Therefore, Minqin and Pingliang were selected as sand dust exposure region and control area, respectively. The incidence of respiratory system diseases and symptoms was determined through a structured respiratory health questionnaire (ATS-DLD-78-A) and personal interviews. The subjects comprised 728 farmers (Minqin, 424; Pingliang, 304) aged 40 years or older, who had nondocumented occupational history to industrial dust exposure. Prevalences (odds ratio [OR], 95% confidence interval [CI]) of chronic rhinitis, chronic bronchitis, and chronic cough increased 9.6% (3.141, 1.776-5.555), 7.5% (2.468, 1.421-4.286), and 10.2% (1.787, 1.246-2.563) in Minqin comparison with Pingliang, respectively, and the differences were significant (p <.01).

Non-anthropogenic dust exposure and asthma medication purchase in children

Air pollution has been shown to increase frequency of asthma attacks, as usually measured by hospitalisation rates. We hypothesise that purchase of asthma reliever medications will reflect a broader association between the environmental exposure and asthma exacerbations. In a time series analysis, we estimated the association of dust storms with mild asthma manifestations, as indicated by medication purchases, during 2005-2011. We compared our results with the estimation of the association of dust storms with hospitalisations due to asthma and asthma-like symptoms. We detected 289 dust storms characterised by high levels of particulate matter <10 μm in diameter. We identified 42,920 children with asthma, wheezing or asthma-like symptoms, of whom 2418 were hospitalised. We observed a higher risk of asthma medication purchase on the day of a mild dust storm (relative risk 1.05, 95% CI 1.00-1.10). The next peak in drug purchases was 3 days later and was more pronounced among Bedouin-Arab children. Stratified analyses showed higher risks for hospitalisation among Bedouin-Arab children; especially among children living in temporary houses (relative risk 1.33, 95% CI 1.04-1.71). We observed an increased risk of asthma medication purchase associated with mild dust storms. The risk observed for hospitalisation was more pronounced among the rural Bedouin-Arab population.

Effect of Asian sand dust on Japanese cedar pollinosis

OBJECTIVE

Asian sand dust (ASD), originating in the deserts of Mongolia and China, spreads over large areas and is associated with adverse effects on human health in East Asia, including asthma, heart disease, and some allergic diseases. However, the effect of ASD on patients with seasonal allergic rhinitis caused by Japanese cedar pollen (SAR-JCP), the most common form of allergic rhinitis, remains unclear. The aim of this study was to investigate the effect of ASD on SAR-JCP patients.

METHODS

A total of 41 patients with SAR-JCP recorded nasal and ocular allergic symptom scores in a diary. We assessed the influence of ASD events on patients with SAR-JCP during the JCP season and before and after the JCP season.

RESULTS

ASD events did not influence nasal and ocular allergy symptoms during the JCP season. Scores for sneezing and runny nose were significantly increased by ASD events in the pre-JCP season. Ocular symptom scores were significantly increased by ASD events in the post-JCP season.

CONCLUSION

Our results suggest that ASD may exacerbate allergy symptoms even before mass scattering of JCP, which usually does not cause allergic symptoms in patients with SAR-JCP. ASD also induced conjunctivitis symptoms after the JCP season. However, we did not observe any adverse effects of ASD on allergic symptoms during the JCP season.

Asian dust particles induce macrophage inflammatory responses via mitogen-activated protein kinase activation and reactive oxygen species production

Asian dust is a springtime meteorological phenomenon that originates in the deserts of China and Mongolia. The dust is carried by prevailing winds across East Asia where it causes serious health problems. Most of the information available on the impact of Asian dust on human health is based on epidemiological investigations, so from a biological standpoint little is known of its effects. To clarify the effects of Asian dust on human health, it is essential to assess inflammatory responses to the dust and to evaluate the involvement of these responses in the pathogenesis or aggravation of disease. Here, we investigated the induction of inflammatory responses by Asian dust particles in macrophages. Treatment with Asian dust particles induced greater production of inflammatory cytokines interleukin-6 and tumor necrosis factor-α (TNF-α) compared with treatment with soil dust. Furthermore, a soil dust sample containing only particles ≤10 μm in diameter provoked a greater inflammatory response than soil dust samples containing particles >10 μm. In addition, Asian dust particles-induced TNF-α production was dependent on endocytosis, the production of reactive oxygen species, and the activation of nuclear factor-κB and mitogen-activated protein kinases. Together, these results suggest that Asian dust particles induce inflammatory disease through the activation of macrophages.

The effect of Asian sand dust-activated respiratory epithelial cells on activation and migration of eosinophils

CONTEST: Asian sand dust (ASD) contains various chemical and microbiological materials. ASD aggravate the inflammatory response of respiratory epithelial cells and symptoms of asthma.

OBJECTIVE

To evaluate the inflammatory effects of ASD on the activation of bronchial epithelial cells and the effect on the activation and migration of eosinophils.

MATERIALS AND METHODS

BEAS-2B cells were exposed to three forms of ASD: particles less than 10 μm in diameter (PM), dried sand dust (SD) and sand dust collected from the Gobi Desert (GB). Activation of the epithelial cells was determined using interleukin-6 (IL-6), IL-8, granulocyte macrophage colony-stimulating factor (GM-CSF), regulated on activation normal T expressed and secreted (RANTES), and eotaxin. Eosinophil migration was induced with bronchial epithelial cell conditioned medium. Eosinophils were stimulated with the ASDs and production of superoxide and eosinophil cationic protein was measured.

RESULTS

PM and SD enhanced the production of IL-6, IL-8 and RANTES. However, only IL-6 production was significantly increased with GB. Conditioned medium stimulated PM and SD enhanced the migration of eosinophils. PM and SD strongly activated eosinophils.

DISCUSSION AND CONCLUSIONS

ASD, which contains smaller particles and air pollutants, might exacerbate the inflammatory process of bronchial tissue and asthmatic symptoms with the production of inflammatory mediators and tissue eosinophilia.

Effects on asthma and induction of interleukin-8 caused by Asian dust particles collected in western Japan

OBJECTIVE

Asian dust storms (ADS) contain various airborne particles that may augment airway inflammation by increasing the level of interleukin-8. The objective of the study was to investigate the association of exposure to an ADS with worsening of symptoms of adult asthma and the effect of ADS particles on interleukin-8 transcriptional activity.

METHODS

The subjects were 112 patients with mild to moderate asthma who recorded scores for their daily upper and lower respiratory tract symptoms and measured morning peak expiratory flow (PEF) from March to May 2011. Interleukin-8 transcriptional activity was assessed in THP-G8 cells that were exposed to airborne particles collected during days of ADS exposure.

RESULTS

Of the 112 patients, 31 had comorbid allergic rhinitis (AR) and/or chronic sinusitis (CS), and had worsened scores for upper respiratory tract symptoms on ADS days compared to non-ADS days. Scores for lower respiratory tract symptoms during ADS days were higher than non-ADS days in all patients. Three patients also had unscheduled hospital visits for exacerbation of asthma on ADS days. However, there was no significant difference in daily morning PEF between ADS and non-ADS days. Airborne particles collected on ADS days induced interleukin-8 transcriptional activity in THP-G8 cells compared to the original soil of the ADS.

CONCLUSION

Exposure to an ADS aggravates upper and lower tract respiratory symptoms in patients with adult asthma. ADS airborne particles may increase airway inflammation through enhancement of interleukin-8 transcriptional activity.

Microarray analysis of gene expression alteration in human middle ear epithelial cells induced by micro particle

OBJECTIVES

The primary aim of this study is to reveal the effect of particulate matter (PM) on the human middle ear epithelial cell (HMEEC).

METHODS

The HMEEC was treated with PM (300 μg/ml) for 24 h. Total RNA was extracted and used for microarray analysis. Molecular pathways among differentially expressed genes were further analyzed by using Pathway Studio 9.0 software. For selected genes, the changes in gene expression were confirmed by real-time PCR.

RESULTS

A total of 611 genes were regulated by PM. Among them, 366 genes were up-regulated, whereas 245 genes were down-regulated. Up-regulated genes were mainly involved in cellular processes, including reactive oxygen species generation, cell proliferation, apoptosis, cell differentiation, inflammatory response and immune response. Down-regulated genes affected several cellular processes, including cell differentiation, cell cycle, proliferation, apoptosis and cell migration. A total of 21 genes were discovered as crucial components in potential signaling networks containing 2-fold up regulated genes. Four genes, VEGFA, IL1B, CSF2 and HMOX1 were revealed as key mediator genes among the up-regulated genes. A total of 25 genes were revealed as key modulators in the signaling pathway associated with 2-fold down regulated genes. Four genes, including IGF1R, TIMP1, IL6 and FN1, were identified as the main modulator genes.

CONCLUSIONS

We identified the differentially expressed genes in PM-treated HMEEC, whose expression profile may provide a useful clue for the understanding of environmental pathophysiology of otitis media. Our work indicates that air pollution, like PM, plays an important role in the pathogenesis of otitis media.

Effects of two Asian sand dusts transported from the dust source regions of Inner Mongolia and northeast China on murine lung eosinophilia

The quality and quantity of toxic materials adsorbed onto Asian sand dust (ASD) are different based on dust source regions and passage routes. The aggravating effects of two ASDs (ASD1 and ASD2) transported from the source regions of Inner Mongolia and northeast China on lung eosinophilia were compared to clarify the role of toxic materials in ASD. The ASDs contained different amounts of lipopolysaccharides (LPS) and β-glucan (ASD1<ASD2) and SiO2 (ASD1>ASD2). CD-1 mice were instilled intratracheally with ASD1, ASD2 and/or ovalbumin (OVA) four times at 2-week intervals. ASD1 and ASD2 enhanced eosinophil recruitment induced by OVA in the submucosa of the airway, with goblet cell proliferation in the bronchial epithelium. ASD1 and ASD2 synergistically increased OVA-induced eosinophil-relevant cytokines interleukin-5 (IL-5), IL-13 (ASD1<ASD2) and chemokine eotaxin (ASD1>ASD2) in bronchoalveolar lavage fluid. ASD2 aggravating effects on lung eosinophilia were greater than ASD1. The role of LPS and β-glucan in ASD2 on the production of pro-inflammatory mediators was assessed using in vitro bone marrow-derived macrophages (BMDMs) from wild type, Toll-like receptor 2-deficient (TLR2-/-), TLR4-/-, and MyD88-/- mice (on Balb/c background). ASD2-stimulated TLR2-/- BMDMs enhanced IL-6, IL-12, TNF-α, MCP-1 and MIP-1α secretion compared with ASD2-stimulated TLR4-/- BMDMs. Protein expression from ASD2-stimulated MyD88-/- BMDM were very low or undetectable. The in vitro results indicate that lung eosinophilia caused by ASD is TLR4 dependent. Therefore, the aggravation of OVA-related lung eosinophilia by ASD may be dependent on toxic substances derived from microbes, such as LPS, rather than SiO2.

Effects of fetal exposure to urban particulate matter on the immune system of male mouse offspring

Urban particulate matter (UPM) has been shown to have an aggravating effect on Th2-associated immune systems in adult mice. However, the effects of fetal exposure to UPM on immune response in offspring have not been elucidated. In the present study, we administered UPM (200 µg/animal) by intratracheal injection to pregnant dams on days 7 and 14 of gestation. Subsequently, 9- and 24-week-old male offspring were intratracheally injected with ovalbumin (OVA) (four times at 2-week intervals) to create a mouse model of bronchial asthma. We then evaluated the progression of allergic manifestations in the offspring through histological findings, the number of inflammatory cells in bronchoalveolar lavage fluid (BALF), and protein concentration of cytokines and chemokines in BALF 5, 10, 15, and 30 weeks after birth. Histological examination showed that fetal exposure to UPM alone caused slight eosinophil and lymphocyte infiltration in the submucosa of the airway and bronchial epithelium and significant increases in the number of macrophages. Moreover, postnatal intratracheal administration of OVA to offspring exposed to UPM in utero caused significant increases in the numbers of macrophages, eosinophils, and lymphocytes and in the concentrations of their relevant cytokines and chemokines, showing that fetal exposure to UPM aggravated the chemically sensitized immune system of male offspring.

Asian Dust Particles Induce TGF-β(1) via Reactive Oxygen Species in Bronchial Epithelial Cells

Background

Asian dust storms can be transported across eastern Asia. In vitro, Asian dust particle-induced inflammation and enhancement of the allergic reaction have been observed. However, the fibrotic effects of Asian dust particles are not clear. Production of transforming growth factor β₁ (TGF-β₁) and fibronectin were investigated in the bronchial epithelial cells after exposure to Asian dust particulate matter (AD-PM10).

Methods

During Asian dust storm periods, air samples were collected. The bronchial epithelial cells were exposed to AD-PM10 with and without the antioxidant, N-acetyl-L-cysteine (NAC). Then TGF-β₁ and fibronectin were detected by Western blotting. The reactive oxygen species (ROS) was detected by the measurement of dicholorodihydrofluorescin (DCF), using a FACScan, and visualized by a confocal microscopy.

Results

The expression of TGF-β₁, fibronectin and ROS was high after being exposed to AD-PM10, compared to the control. NAC attenuated both TGF-β₁ and fibronectin expression in the AD-PM10-exposed the bronchial epithelial cells.

Conclusion

AD-PM10 may have fibrotic potential in the bronchial epithelial cells and the possible mechanism is AD-PM10-induced intracellular ROS.

Adverse Health Effects of Asian Dust Particles and Heavy Metals in Japan

Asian dust events are now considered an environmental problem rather than a natural seasonal phenomenon. In this study, we evaluated the associations between daily adverse health effects and Asian dust events in Yonago, Japan. Participants included 54 healthy volunteers, who were distributed survey sheets on nasal, ocular, respiratory, and skin effects in February 2009. Moreover, we collected meteorological and air pollutant (nitric oxide, sulfur dioxide, suspended particulate matter) data and determined pollen and metallic element concentrations in total suspended particulates. Both soil-derived metals (Fe, Ca, Al) and contaminating metals (Pb, Cr, Mn, Ni, Zn) were significantly increased on Asian dust days. Multiple regression analyses showed that the score of the skin effect was significantly associated with the levels of suspended particulate matter and Ni. The results show that increased air pollutants on Asian dust days may have skin effects.

Pathological Study of Chronic Pulmonary Toxicity Induced by Intratracheally Instilled Asian Sand Dust (Kosa)

Asian sand dust (ASD) events are associated with an increase in pulmonary morbidity and mortality. The number of ASD events has increased rapidly in the east Asian region since 2000. To study the chronic lung toxicity of ASD, saline suspensions of low doses (200 and 400 µg) and high doses (800 and 3,000 µg) of ASD were intratracheally instilled into ICR mice. Animals were sacrificed at 24 hr, 1 week, or 1, 2, or 3 months after instillation. Histopathological examination revealed that ASD induced acute inflammation at 24 hr after instillation. The acute inflammation was transient and subsided at 1 week and 1 month after instillation. At 2 and 3 months after instillation, focal infiltration of lymphocytes with accumulation of epithelioid macrophages, which is a suggestive finding of transformation to granuloma, and granuloma formation were occasionally observed. Aggregation of macrophages containing particles was observed in the pulmonary lymph nodes at 3 months after instillation in high-dose groups. Prolonged inflammatory foci (granuloma) and presence of ASD particles in pulmonary lymph nodes would have a chance to induce immunological modulation leading to adverse health effects in the exposed animals.

Asian sand dust enhances allergen-induced th2 allergic inflammatory changes and mucin production in BALB/c mouse lungs

Purpose

Recent studies have reported that Asian sand dust (ASD) has a potential risk of aggravating airway inflammation. The purpose of this study was to investigate the effect of ASD on inflammation and mucin production in the airways of allergic mice.

Methods

Forty BALB/c female mice were divided into four groups: saline (group 1); ASD (group 2); ovalbumin (OVA) alone (group 3); and OVA+ASD (group 4). OVA-specific immunoglobulin E (IgE) in serum and interleukin (IL)-4, IL-5, IL-13, and interferon-gamma (IFN-γ) in bronchoalveolar lavage fluid (BALF) were measured by enzyme-linked immunosorbent assay (ELISA). Hematoxylin & eosin (H&E) and Periodic acid-Schiff (PAS) staining was performed on lung tissues. In addition, immunohistochemical staining for IL-4, IL-5, MUC5AC, and transforming growth factor alpha (TGF-α) was conducted.

Results

Serum IgE levels were significantly higher in group 4 than in group 3 (P<0.05). IL-4 and IL-5 in BALF were significantly higher in group 4 than in group 3 (P<0.05, respectively). Based on H&E staining, inflammatory cell numbers were significantly greater in group 4 than in the other groups (P<0.05). The number of PAS-positive cells was also significantly greater in groups 3 and 4 than in groups 1 and 2 (P<0.05). The numbers of IL-4 and IL-5-positive cells were higher in group 4 than in group 3 (P<0.05). The number of MUC5AC and TGF-α-positive cells were also higher in group 4 than in group 3 (P<0.05).

Conclusions

Our data suggest that ASD increases cytokine expression and mucin production in an allergic murine model. The increased inflammatory reactions were related to cytokine production.

Effect of Asian Sand Dust on Mucin Production in NCI-H292 Cells and Allergic Murine Model

Objective. To investigate the effect of Asian sand dust (ASD) on mucin production in human respiratory epithelial cells in vitro and in allergic murine nasal epithelial cells.

Study Design. Controlled, in vitro.

Setting. Academic research laboratory.

Materials and Methods. Human NCI-H292 cells were treated with ASD and analyzed by immunostaining, reverse transcriptase–polymerase chain reaction for MUC5AC mRNA expression, and Periodic Acid Schiff (PAS) staining. Forty female BALB/c mice were classified into 4 groups. Two groups were sensitized with ovalbumin (OVA), and 1 of these was treated with ASD (ASD+OVA). The 2 nonsensitized groups were treated with ASD or saline. Then the murine nasal mucosal tissues were evaluated by hematoxylin and eosin (H&E) staining, PAS staining, and immunostaining for MUC5AC and transforming growth factor (TGF)-α proteins.

Results. The numbers of MUC5AC-immunopositive NCI-H292 cells and PAS-positive NCI-H292 cells were significantly higher in the ASD-treated cells than in the control cells ( P = .039 and P = .029, respectively). MUC5AC mRNA expression in the cells increased with increasing concentrations of ASD. In the murine nasal epithelial tissues, the numbers of eosinophils and PAS-positive cells were significantly higher in the ASD+OVA group than in the OVA group (H&E staining, P = .037; PAS staining, P = .019). At 2 weeks, the numbers of MUC5AC- and TGF-α–positive cells in the nasal epithelial tissue were significantly higher in the ASD+OVA group than in the OVA group ( P = .031 and P = .033, respectively).

Conclusion. ASD can induce mucin production in respiratory epithelial cells.

A case-crossover analysis of Asian dust storms and mortality in the downwind areas using 14-year data in Taipei

This study aims to assess the association between Asian dust storms (ADS) and daily mortality in Taipei, Taiwan. A time-stratified case-crossover design was used to investigate the effects of ADS on mortality. Odds ratios (ORs) of total non-accidental (ICD-9 <800), cardiovascular (ICD-9 390-459, 785), and respiratory deaths (ICD-9 460-519, 786) were estimated for residents in Taipei metropolis over a 14-year study period between 1994 and 2007 by conditional logistic regression. Air pollution levels and temperature data were recorded by a network of 16 monitoring stations spreading around Taipei. Compared with reference days, particulate matter with aerodynamic diameter less than 10 and 2.5μm (PM(10) and PM(2.5)) increased statistically significantly by 24.2μg/m(3) and 7.9μg/m(3) per dust day, respectively. There were also statistically significant increases in sulfur dioxide (SO(2)) and ozone (O(3)) but decreases in temperature during ADS. Excess deaths were increased significantly for residents of all ages for total non-accidental deaths, with OR=1.019 (95% CI 1.003-1.035), and also for residents above 65years old, with OR=1.025 (95% CI 1.006-1.044) for total non-accidental deaths and OR=1.045 (95% CI 1.0011-1.081) for cardiovascular deaths, respectively but not for respiratory deaths during ADS. Such increases in mortality remained statistically significant in the regression models with either SO(2) or O(3). This study found that acute exposure to long-range transported Asian dust can increase the number of non-accidental and cardiovascular deaths for people of all ages and the elderly population aged above 65 on the dust storm days in Taipei, Taiwan. Further studies are still needed to find out whether mass concentrations alone or specific components in PM are responsible for excess cardiovascular deaths by ADS.

Pollen augments the influence of desert dust on symptoms of adult asthma patients

BACKGROUND

East Asian desert dust storms that occur during mainly spring are called Asian dust storms (ADS). Our objective was to study the association of pollen and ADS with symptoms of adult asthma patients in Japan.

METHODS

We designed a telephone survey to investigate the upper and lower respiratory, ocular, and skin symptoms of asthma patients during ADS in February, March, and December on 2009. Peak expiratory flow (PEF) was also measured from February to May.

RESULTS

We surveyed 106 patients in February, 101 patients in March, and 103 patients in December. In February and March, Japanese cedar and/or cypress pollen was also in the atmosphere during ADS, but no pollen was identified during December survey. Worsening of upper or lower respiratory, ocular, or skin symptoms was noted by 20.8% of patients in February, 33.7% in March, and 16.5% in December. Worsening of symptoms was significantly more common in March than in February or December. Two patients needed emergency treatment for exacerbation during ADS in March, but no patient needed hospitalization in any period. There was no significant difference of the daily morning PEF/personal best PEF ratio between ADS days and control days. However, in patients with worsening of upper and/or lower respiratory tract symptoms, the daily morning PEF/personal best ratio was significantly associated with the atmospheric level of particulate matter, but not with levels of pollen or other air pollutants.

CONCLUSIONS

Pollen augmented symptoms in adult asthma patients, but ADS on its own also were able to aggravate symptoms and pulmonary function.

Correlation between Asian dust storms and worsening asthma in Western Japan

BACKGROUND

Severe wind storms during spring in East Asia, called Asian dust storms (ADS), have been assessed in the past for their effect on health in Asian countries. Our objective was to study the ADS association with asthma symptoms in adult patients in Japan.

METHODS

We designed a telephone survey to assess ADS influence on upper and lower respiratory, ocular and cutaneous symptoms in 98 patients with adult asthma from April to May 2007. Peak expiratory flow (PEF) was also measured from February to May.

RESULTS

Worsening lower respiratory symptoms were noted by 22 of 98 patients during ADS in April, when Japanese cedar pollen levels also increased. During ADS in May, however, Japanese cedar and cypress pollen levels were not elevated, 11 patients had worsening of lower respiratory symptoms. None required emergency treatment for the exacerbation. Lower respiratory symptoms worsening most were cough and sputum; this was more common in patients with allergic rhinitis or atopy than in those without (P < 0.05). Min%Max differed significantly at 88.7 ± 6.6% during dust dispersion period, defined as the ADS day plus the next 6 days, versus 92.0 ± 5.3% during the 7-day period before a dust storm.

CONCLUSIONS

We found that ADS aggravated lower respiratory symptoms in adult patients with asthma, but this influence was mild.

Soil microbial community structure in an Asian dust source region (Loess plateau)

The bacterial community structure in four geographically isolated arid regions on the Loess plateau, China, a source of Asian dust, was investigated using a 16S rRNA gene. Denaturing gradient gel electrophoresis and sequencing demonstrated that community diversity in the Loess plateau was low, and a common Alphaproteobacteria phylotype was identified. Phylogenetic analyses of arid soils revealed that most phylotypes had low similarity with known strains in various phyla, suggesting that these regions contain phylogenetically divergent and unknown bacteria.

Asian sand dust enhances rhinovirus-induced cytokine secretion and viral replication in human nasal epithelial cells

CONTEXT

Asian sand dust (ASD) originating in the arid deserts of Mongolia and China causes annual severe air pollution events in the Asia-Pacific area, including Korea, Japan, and China. ASD is thought to impact public health by aggravating or inducing respiratory illness. Among the most common respiratory illnesses is the common cold caused by rhinovirus (RV) infection. To date, however, the impact of ASD on RV infection has not been studied.

OBJECTIVE

In this study, we investigated the effect of ASD on RV infection in human nasal epithelial cells.

METHODS

Primary human nasal epithelial cells grown at an air-liquid interface were treated with ASD and/or RV. After RV infections were confirmed using semi-nested reverse transcription-polymerase chain reaction (RT-PCR), mRNA expression and protein secretion of the inflammatory cytokines interferon-γ (IFN-γ), interleukin-1β (IL-1β),IL-6, and IL-8, indicators of the severity of RV-induced inflammation, were measured by real-time PCR and enzyme-linked immunosorbent assays. Viral titer was also assayed by culturing viruses to compare viral replication between RV-only and ASD-plus-RV groups.

RESULTS

ASD significantly increased RV-induced IFN-γ, IL-1β, IL-6, and IL-8 mRNA levels and protein secretion in primary nasal epithelial cells. In addition, ASD caused a significant increase in RV replication.

CONCLUSIONS

Our results suggest that ASD may potentiate common cold symptoms associated with RV infection not only by enhancing IFN-γ, IL-1β, IL-6, and IL-8 secretion, but also by increasing viral replication.

The effect of Asian dust events on the daily symptoms in Yonago, Japan: a pilot study on healthy subjects

The occurrence of Asian dust events is a frequent problem, with associated health issues throughout Northeast Asia. However, the effects of Asian dust on human health are not well known in Japan. The authors evaluated the association between daily symptoms and dust events in Yonago, Japan. The subjects were 54 healthy individuals who were distributed survey sheets on nasopharyngeal, ocular, respiratory, and skin symptoms, which were quantified in February 2009. The authors investigated the symptoms of the subjects on Asian dust days and control days, and compared the symptom scores with measures of suspended particulate matter (SPM), which is the indicator of Asian dust. The scores for symptoms were significantly higher on Asian dust days than on control days (p=.020). The skin symptom scores were positively correlated with the SPM level (p<.001). These results provide preliminary evidence that Asian dust influence the symptoms of healthy subjects, although the symptoms are not severe.

Urban particulate matter in Beijing, China, enhances allergen-induced murine lung eosinophilia

It has been reported that ambient particulate matter (PM) in some large cities, such as Beijing, China, causes adverse respiratory health effects. However, there is currently no experimental report on the relationship between bronchial asthma and urban PM (UPM) in northeast Asia. In this study, the microbial and chemical substances adsorbed onto UPM collected in Beijing were excluded by heat-treatment at 360 degrees C for 30 min. The effects of UPM or heated UPM (H-UPM) toward allergic lung inflammation were compared in murine lungs to investigate the role of organic substances. ICR mice were administrated intratracheally with the two kinds of UPM and/or ovalbumin (OVA) 4 times at 2-week intervals. UPM and H-UPM enhanced eosinophil recruitment induced by OVA in the alveoli and in the submucosa of the airway, which has a goblet cell proliferation in the bronchial epithelium. UPM and H-UPM synergistically increased Th-2 cytokines--interleukin (IL)-4 and IL-13, eosinophil-relevant cytokines and chemokines, such as IL-5 and monocyte chemotactic protein-3 (MCP-3), induced by OVA in bronchoalveolar lavage fluid (BALF). The enhancing effects were much greater in UPM than in H-UPM. UPM induced adjuvant effects on specific immunoglobulin E (IgE) and IgG1 production by OVA. In an in vitro study using RAW264.7 cells, UPM increased the expression of Toll-like receptor 2 (TLR2) mRNA, but not TLR4 mRNA. H-UPM caused no expression of both TLR mRNAs. These results suggest that the aggravated lung eosinophilia in UPM was due to activation of a Th2-associated immune response via the activation of TLR2 by microbial materials. Chemical materials of air pollutant origin contained in UPM, and inorganic components (elemental carbon, mineral elements) in H-UPM, could also cause the aggravation.

Pathological Study of Acute Pulmonary Toxicity Induced by Intratracheally Instilled Asian Sand Dust (Kosa)

The objective of this study was to investigate acute lung toxicity caused by Asian sand dust. Simulated Asian sand dust collected from the Tennger desert in China (CJ-2 particles) and Asian sand dust collected from the atmosphere in Japan (Tottori particles) were used. Saline suspensions of 50, 200, 800, and 3,000 µg Asian sand dust were intratracheally instilled to ICR mice. Localized accumulation of the dust particles was observed in the bronchioles and the alveoli of the lung tissues; acute inflammatory changes characterized by infiltration of macrophages and neutrophils were observed around the particles. Degenerated alveolar walls and bronchial epithelial cells, as well as a weakened positive immunolabeling for laminin, were observed to be associated with particle attachment. Positive immunolabelings for interleukin-6, tumor necrosis factor–α inducible nitric oxide synthase, and dimeric copper- and zinc-containing superoxide dismutase were observed mainly in the inflammatory cells in the lesions; these findings were not observed in the controls or in areas lacking lesions. These results suggest that Asian sand dust particles caused damage to the lung tissue through a direct physical effect. In addition, secondary released cytokines and oxidative stress generated in the lesion may be involved in the development of the acute lung toxicity.

Desert dust exposure is associated with increased risk of asthma hospitalization in children

RATIONALE

Desert dust particles, including quartz, which causes inflammatory responses in the airway in animal studies, are transported to widespread regions around the globe. Epidemiologically, areas impacted by desert dust storms, such as communities in the Middle East and the Caribbean, seem to have higher incidences of asthma than might be expected.

OBJECTIVES

We investigated the magnitude of association between airborne mineral dust concentration and hospitalization of children for asthma exacerbation by using Light Detection And Ranging (LIDAR) with a polarization analyzer for an exposure measurement, which can distinguish mineral dust particles from other particles.

METHODS

A case-crossover design was used. The exposure measurement was LIDAR's nonspherical extinction coefficient. The outcome measurement was hospitalization of children aged 1 to 15 years for asthma exacerbation in eight principal hospitals in Toyama, a local area in Japan bordering the Japan Sea, during February to April, 2005 to 2009.

MEASUREMENTS AND MAIN RESULTS

During the study period, there were 620 admissions for asthma exacerbation, and 6 days with a heavy dust event (daily mineral dust concentration > 0.1 mg/m(3)). Conditional logistic regression showed a statistically significant association between asthma hospitalization and a heavy dust event. The crude odds ratio (OR) of the heavy dust event for hospitalization on the day was 1.88 (95% confidence interval [CI], 1.04-3.41; P = 0.037), and the OR of heavy dust event during the previous week was 1.83 (95% CI, 1.31-2.56; P = 0.00043). The OR adjusted by other air pollutant levels, pollen, and meteorological factors was 1.71 (95% CI, 1.18-2.48; P = 0.0050).

CONCLUSIONS

Heavy dust events are associated with an increased risk of hospitalizations for asthma.