Effects of Asian sand dust on mucin gene expression and activation of nasal polyp epithelial cells

Saharan dust induces the lung disease-related cytokines granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor

Desert dust exposure is associated with adverse respiratory health effects. Desert dust is a complex pollutant mixtures that includes respirable crystalline and amorphous particles, metals, and microbial constituents. Given the health effects of desert dust and its heterogeneity, as yet unidentified harmful biological pathways may be triggered. Therefore, we exposed human in vitro air-liquid interface co-cultures of alveolar epithelial A549 cells and THP-1 macrophages to Saharan dust (SD). For comparison, we used the known pulmonary toxicant DQ12 quartz dust. Via RNA sequencing, we identified that SD but not DQ12 increased the gene expression of granulocyte-macrophage colony-stimulating factor (GMCSF) and granulocyte colony-stimulating factor (GCSF). These findings were confirmed by quantitative reverse transcriptase PCR. SD dose-dependently upregulated GMCSF and GCSF expression with significant 7 and 9-fold changes, respectively, at the highest tested concentration of 31 µg/cm2. Furthermore, we observed that SD significantly enhanced the secretion of GM-CSF and G-CSF by 2-fold. Both cytokines have previously been associated with lung diseases such as asthma and fibrosis. Hence, we present two molecular messengers that may contribute to the adverse health effects of desert dust and might serve as drug targets for this globally relevant non-anthropogenic air pollutant.

The impact of benzo[a]pyrene on murine allergic airway inflammation via epigenetic remodeling

Simultaneous exposure to both BaP and house dust mites (HDM) has been shown to exacerbate pulmonary inflammation and hyperresponsiveness in a murine asthma model. The mechanistic insight into epigenetic inheritance for this effect, however, remains to be clarified. As such, in this study, we explore the molecular basis for the enhancement of asthma. Female BAL/C mice were intranasally administered HDM (25 µg in 25 μL saline) and/or BaP (10 μg/kg) every other day for 9 weeks. RNA sequencing and DNA methylation assessment were used to explore the underlying mechanism. Following simultaneous exposure to HDM and BaP, mice exhibited pulmonary inflammation and the transcript level of IL4i1b, muc4 and IL22ra2 that were associated with altered DNA methylation, suggesting that there may be an epigenetic basis for BaP-induced asthma exacerbation. Our data suggest that DNA methylation is a major epigenetic modification that accompanies airway remodeling associated with changes in the allergic mice.

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.

Viral respiratory infections and air pollutants

Air pollution is a public health issue of global importance and a risk factor for developing cardiorespiratory diseases. These contaminants induce reactive oxygen species (ROS) and increased pro-inflammatory cytokines such as IL-1β, IL-6, and IL-8, triggering the inflammatory response that alters cell and tissue homeostasis and facilitates the development of diseases. The effects of air pollutants such as ozone, particulate matter (PM10, PM2.5, and PM0.1), and indoor air pollutants on respiratory health have been widely reported. For instance, epidemiological and experimental studies have shown associations between hospital admissions for individual diseases and increased air pollutant levels. This review describes the association and relationships between exposure to air pollutants and respiratory viral infections, especially those caused by the respiratory syncytial virus and influenza virus. The evidence suggests that exposure to air contaminants induces inflammatory states, modulates the immune system, and increases molecules' expression that favors respiratory viruses' pathogenesis and affects the respiratory system. However, the mechanisms underlying these interactions have not yet been fully elucidated, so it is necessary to develop new studies to obtain information that will allow health and policy decisions to be made for the adequate control of respiratory infections, especially in the most vulnerable population, during periods of maximum air pollution.

Effect of Korean Red Ginseng and Rg3 on Asian Sand Dust-Induced MUC5AC, MUC5B, and MUC8 Expression in Bronchial Epithelial Cells

Korean Red ginseng (KRG), commonly used in traditional medicine, has anti-inflammatory, anti- oxidative, and anti-tumorigenic properties. Asian sand dust (ASD) is known to aggravate upper and lower airway inflammatory responses. BEAS-2B cells were exposed to ASD with or without KRG or ginsenoside Rg3. Mucin 5AC (MUC5AC), MUC5B, and MUC8 mRNA and protein expression levels were determined using quantitative RT-PCR and enzyme-linked immunosorbent assay. Nuclear factor kappa B (NF-κB), activator protein 1, and mitogen-activated protein kinase expression and activity were determined using western blot analysis. ASD induced MUC5AC, MUC5B, and MUC8 mRNA and protein expression in BEAS-2B cells, which was significantly inhibited by KRG and Rg3. Although ASD-induced mucin expression was associated with NF-κB and p38 mitogen-activated protein kinase (MAPK) activity, KRG and Rg3 significantly suppressed only ASD-induced NF-κB expression and activity. KRG and Rg3 inhibited ASD-induced mucin gene expression and protein production from bronchial epithelial cells. These results suggest that KRG and Rg3 have potential for treating mucus-producing airway inflammatory diseases.

The peroxisome proliferator-activated receptor gamma (PPARγ) agonist, rosiglitazone, ameliorates neurofunctional and neuroinflammatory abnormalities in a rat model of Gulf War Illness

Background

Gulf War (GW) Illness (GWI) is a debilitating condition with a complex constellation of immune, endocrine and neurological symptoms, including cognitive impairment, anxiety and depression. We studied a novel model of GWI based on 3 known common GW exposures (GWE): (i) intranasal lipopolysaccharide, to which personnel were exposed during desert sand storms; (ii) pyridostigmine bromide, used as prophylaxis against chemical warfare; and (iii) chronic unpredictable stress, an inescapable element of war. We used this model to evaluate prophylactic treatment with the PPARγ agonist, rosiglitazone (ROSI).

Methods

Rats were subjected to the three GWE for 33 days. In series 1 and 2, male and female GWE-rats were compared to naïve rats. In series 3, male rats with GWE were randomly assigned to prophylactic treatment with ROSI (GWE-ROSI) or vehicle. After the 33-day exposures, three neurofunctional domains were evaluated: cognition (novel object recognition), anxiety-like behaviors (elevated plus maze, open field) and depression-like behaviors (coat state, sucrose preference, splash test, tail suspension and forced swim). Brains were analyzed for astrocytic and microglial activation and neuroinflammation (GFAP, Iba1, tumor necrosis factor and translocator protein). Neurofunctional data from rats with similar exposures were pooled into 3 groups: naïve, GWE and GWE-ROSI.

Results

Compared to naïve rats, GWE-rats showed significant abnormalities in the three neurofunctional domains, along with significant neuroinflammation in amygdala and hippocampus. There were no differences between males and females with GWE. GWE-ROSI rats showed significant attenuation of neuroinflammation and of some of the neurofunctional abnormalities.

Conclusion

This novel GWI model recapitulates critical neurofunctional abnormalities reported by Veterans with GWI. Concurrent prophylactic treatment with ROSI was beneficial in this model.

Comparison between in vitro toxicities of tobacco- and menthol-flavored electronic cigarette liquids on human middle ear epithelial cells

Since electronic-cigarettes (e-cigarettes) are considered less toxic than conventional tobacco smoking, the use of e-cigarettes has increased, and the market for e-cigarette liquids (e-liquids) is continuously increasing. However, many studies showed that e-cigarettes may cause various harmful effects in lung, oral and heart. In this study, we investigated the effects of e-liquids on otitis media (OM) using human middle ear epithelial cells (HMEECs). Menthol-flavored e-liquid induced significant cell death in HMEECs (IC50: 1.45 ± 0.14%) and tobacco-flavored e-liquid led to increase in inflammatory cytokine levels and higher mucin production. Flavored e-liquids decreased the mRNA levels of genes encoding epithelial sodium channels (ENaCs) in HMEECs. Apoptosis and autophagy reactions were induced by exposure of HMEECs to menthol- and tobacco-flavored e-liquids. Tobacco-flavored e-liquids caused a greater increase in the levels of autophagosome marker, LC3-II, compared to menthol-flavored e-liquids, which was followed by cell death. These results demonstrate that flavored e-liquids cause cytotoxicity via apoptosis, autophagy, inflammatory response, and mucin production in HMEECs. The flavors present in e-liquids might be a risk factor for the development of otitis media.

Asian Sand Dust Upregulates IL-6 and IL-8 via ROS, JNK, ERK, and CREB Signaling in Human Nasal Fibroblasts

Background

Asian sand dust (ASD) profoundly affects respiratory health by inducing inflammation and causing upper airway inflammatory diseases. Interleukin (IL)-6 and IL-8 are pro-inflammatory mediators that are involved in upper airway inflammatory diseases. However, the effect of ASD on the production of IL-6 and IL-8 in nasal fibroblasts has not been adequately studied. We investigated the effect of ASD on the induction of pro-inflammatory mediators and its underlying mechanisms in nasal fibroblasts.

Methods

Real-time cytotoxicity assays were used to determine the effect of ASD on the viability of fibroblasts. Enzyme-linked immunosorbent assays and real-time polymerase chain reactions were performed to determine whether ASD induced the expression of IL-6 and IL-8. Reactive oxygen species (ROS) were quantified using 2, 7-dichlorofluorescein-diacetate and MitoSOX Red. Induction of IL-6 and IL-8 signal transduction pathways by ASD was confirmed by Western blotting. Ex vivo culture of the inferior turbinate tissue was performed to confirm the effects of ASD.

Results

ASD upregulated ROS levels, and this in turn promoted IL-6 and IL-8 expression through the MAPK (JNK and ERK) and CREB signaling pathways in nasal fibroblasts. However, ASD did not induce phosphorylation of p38. Specific inhibitors of each pathway (ROS, JNK, ERK, and CREB inhibitors) suppressed ASD-induced IL-6 and IL-8 upregulation.

Conclusions

ASD induces pro-inflammatory mediators, and the increased levels of IL-6 and IL-8 might be associated with the pathogenesis of chronic rhinosinusitis.

Dust particles-induced intracellular Ca2+ signaling and reactive oxygen species in lung fibroblast cell line MRC5

Epidemiologic interest in particulate matter (PM) is growing particularly because of its impact of respiratory health. It has been elucidated that PM evoked inflammatory signal in pulmonary epithelia. However, it has not been established Ca²⁺ signaling mechanisms involved in acute PM-derived signaling in pulmonary fibroblasts. In the present study, we explored dust particles PM modulated intracellular Ca²⁺ signaling and sought to provide a therapeutic strategy by antagonizing PM-induced intracellular Ca²⁺ signaling in human lung fibroblasts MRC5 cells. We demonstrated that PM10, less than 10 µm, induced intracellular Ca²⁺ signaling, which was mediated by extracellular Ca²⁺. The PM10-mediated intracellular Ca²⁺ signaling was attenuated by antioxidants, phospholipase blockers, polyADPR polymerase 1 inhibitor, and transient receptor potential melastatin 2 (TRPM2) inhibitors. In addition, PM-mediated increases in reactive oxygen species were attenuated by TRPM2 blockers, clotrimazole (CLZ) and N-(p-amylcinnamoyl) anthranilic acid (ACA). Our results showed that PM10 enhanced reactive oxygen species signal by measuring DCF fluorescence and the DCF signal attenuated by both TRPM2 blockers CLZ and ACA. Here, we suggest functional inhibition of TRPM2 channels as a potential therapeutic strategy for modulation of dust particle-mediated signaling and oxidative stress accompanying lung diseases.

MUC4 impairs the anti-inflammatory effects of corticosteroids in patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

Current evidence suggests that membrane-tethered mucins could mediate corticosteroid efficacy, interacting with glucocorticoid receptor (GR) in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Mucin 4 (MUC4)-tethered mucin is expressed in nasal polyp (NP) epithelial cells and upregulated under inflammatory conditions. Moreover, MUC4β has the capacity to interact with other intracellular proteins. We hypothesized that MUC4 modulates corticosteroid efficacy of patients with CRSwNP.

OBJECTIVE

We sought to analyze the role of MUC4 in corticosteroid effectiveness in different cohorts of patients with CRSwNP and elucidate the possible mechanisms involved.

METHODS

Eighty-one patients with CRSwNP took oral corticosteroids for 15 days. Corticosteroid resistance was evaluated by using nasal endoscopy. Expression of MUC4 and MUC4β was evaluated by means of real-time PCR, Western blotting, and immunohistochemistry. BEAS-2B knockdown with RNA interference for MUC4 (small interfering RNA [siRNA]-MUC4) was used to analyze the role of MUC4 in the anti-inflammatory effects of dexamethasone.

RESULTS

Twenty-two patients had NPs resistant to oral corticosteroids. MUC4 expression was upregulated in these patients. In siRNA-MUC4 BEAS-2B airway epithelial cells dexamethasone produced higher anti-inflammatory effects, increased inhibition of phospho-extracellular signal-regulated kinase 1/2, increased mitogen-activated protein kinase phosphatase 1 expression, and increased glucocorticoid response element activation. Immunoprecipitation and immunofluorescence experiments revealed that MUC4β forms a complex with GRα in the nuclei of NP epithelial cells from corticosteroid-resistant patients.

CONCLUSION

MUC4β participates in the corticosteroid resistance process, inhibiting normal GRα nuclear function. The high expression of MUC4 in patients with CRSwNP might participate in corticosteroid resistance.

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.

Asian sand dust increases MUC8 and MUC5B expressions via TLR4-dependent ERK2 and p38 MAPK in human airway epithelial cells

BACKGROUND

Asian sand dust (ASD) is a natural phenomenon and originates from the deserts of China and is known to contain various chemical and biomolecular components that enhance airway inflammation. The overproduction of airway mucins is an important pathologic finding in inflammatory airway diseases. However, the mechanism of ASD on mucin production of airway epithelial cells has not been elucidated.

OBJECTIVE

To investigate the effect and signaling pathway of ASD on mucin expressions in human airway epithelial cells.

METHODS

In the NCI-H292 cells and the primary cultures of human nasal epithelial cells, the effect and signaling pathway of ASD on MUC8 and MUC5B expressions were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, and immunoblot analysis with several specific inhibitors and small interfering RNA (siRNA).

RESULTS

ASD increased MUC8 and MUC5B expressions and activated the phosphorylations of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). U0126 (ERK1/2 MAPK inhibitor) and SB203580 (p38 MAPK inhibitor) inhibited ASD-induced MUC8 and MUC5B expressions. In addition, knockdowns of ERK2 and p38 MAPK by siRNA blocked ASD-induced MUC8 and MUC5B mRNA expressions. Toll-like receptor 4 (TLR4) mRNA expression was increased after treatment with ASD. Knockdown of TLR4 by siRNA blocked ASD-induced MUC8 and MUC5B mRNA expressions. Furthermore, the phosphorylations of ERK1/2 and p38 MAPK were blocked by knockdown of TLR4.

CONCLUSIONS

These results show that ASD induces MUC8 and MUC5B expressions via TLR4-dependent ERK2 and p38 MAPK signaling pathway in human airway epithelial cells.

Adhesion molecules as predictors of nasal polyposis recurrence

BACKGROUND

Nasal polyposis is a chronic inflammation of nasal and paranasal sinuses in the pathogenesis of which adhesion molecules may have a significant role. This study investigates the possible role of certain adhesion molecules, mucins, and oncogenes in nasal polyposis recurrence.

METHODS

A sample study of 21 individuals (17 men and 4 women) aged 47.44 ± 15.10 years with nasal polyposis who had undergone nasal surgery twice was used. Twenty-one individuals aged 46.9 ± 12.8 years suffering from nasal polyposis who had undergone surgery only once in the same period were used as a control sample.

RESULTS

Statistically significant differences between the two groups were observed regarding epithelial membrane antigen (EMA/mucin 1) of stromal cells (p < 0.001) and CD86 stromal expression (p = 0.009). No patient of the control group exhibited high (++) CD86 stromal expression, whereas six patients of the resurgery group did so. When EMA and CD86 were included in a logistic regression model, stromal EMA was found to be positively related to recurrence.

CONCLUSION

Adhesion molecules may relate to nasal polyp prognosis and recurrence rates.

The effect of PM10 on allergy symptoms in allergic rhinitis patients during spring season

Background: Asian sand dust (ASD) that originates in the Mongolian Desert in the spring induces serious respiratory health problems throughout East Asia (China, Korea, Japan). PM₁₀ (particulate matter with an aerodynamic diameter <10 μm) is a major air pollutant component in ASD. We studied the effects of PM₁₀ on allergy symptoms in patients with allergic rhinitis during the spring season, when ASD frequently develops. Methods: We investigated the changes in allergic symptoms in 108 allergic patients and 47 healthy subjects by comparing their 120-day symptom scores from February to May 2012. At the same time, the contributions of pollen count and PM₁₀ concentration were also assessed. We also compared symptom scores before and 2 days after the daily PM₁₀ concentration was >100 μg/m³. Results: The PM₁₀ concentration during the 120 days was <150 μg/m³. No significant correlations were observed between changes in the PM₁₀ concentration and allergic symptom scores (p > 0.05). However, allergic symptoms were significantly correlated with outdoor activity time (p < 0.001). Conclusions: These results demonstrate that a PM₁₀ concentration <150 μg/m³ did not influence allergy symptoms in patients with allergic rhinitis during the 2012 ASD season.

β2-Adrenoceptor involved in smoking-induced airway mucus hypersecretion through β-arrestin-dependent signaling

Progression of chronic obstructive pulmonary disease is associated with small airway obstruction by accumulation of inflammatory mucous exudates. However, the mechanism of mucin hypersecretion after exposure to cigarette smoke (CS) is still not clear. In this study, we explored the contribution of β2-adrenoceptor (β2-AR) signaling to CS extract (CSE)-induced mucus hypersecretion in vitro and examined the effect of a β-blocker on airway mucin hypersecretion in vivo. NCI-H292 epithelial cell line was used to determine the contribution of β2-AR signaling to CSE-induced MUC5AC production by treatment with β2-AR antagonists propranolol and ICI118551 and β2-AR-targeted small interfering RNA. The effect of propranolol on airway mucus hypersecretion was examined in a rat model exposed to CS. MUC5AC expression was assayed by real-time PCR, immunohistochemistry and ELISA. β2-AR and its downstream signaling were detected by western blot analysis. We found that pretreating NCI-H292 cells with propranolol, ICI118551 for 30 min or β2AR-targeted siRNA for 48 h reduced MUC5AC mRNA and protein levels stimulated by CSE. However,inhibiting the classical β2AR-cAMP-PKA pathway didn't attenuate CSE-induced MUC5AC production, while silencing β-arretin2 expression significantly decreased ERK and p38MAPK phosphorylation, thus reduced the CSE-stimulated MUC5AC production. In vivo, we found that administration of propranolol (25 mg kg(-1) d(-1)) for 28 days significantly attenuated the airway goblet cell metaplasia, mucus hypersecretion and MUC5AC expression of rats exposed to CS. From the study, β2-AR-β-arrestin2-ERK1/2 signaling was required for CS-induced airway MUC5AC expression. Chronic propranolol administration ameliorated airway mucus hypersecretion and MUC5AC expression in smoking rats. The exploration of these mechanisms may contribute to the optimization of β2-AR target therapy in chronic obstructive pulmonary disease.

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.

LPS induces MUC5AC expression in human biliary epithelial cells

AIM: To examine whether lipopolysaccharide (LPS) stimulates MUC5AC expression in human biliary epithelial cells.

METHODS: Human biliary epithelial cells were treated with LPS, and MUC5AC mRNA and protein expression was detected by real time-PCR, Western blot and immunohistochemistry 12 and 24 h after LPS treatment.

RESULTS: LPS stimulation significantly increased MUC5AC mRNA expression (3.67 ± 0.22 vs 1.00 ± 0.05, P < 0.05). MUC5AC protein expression was also increased after LPS treatment (0.26 vs 0.59, P < 0.05).

CONCLUSION: LPS can induce MUC5AC expression in human biliary epithelial cells.