Effects of 28 days silicon dioxide aerosol exposure on respiratory parameters, blood biochemical variables and lung histopathology in rats

Silica dust exposure and associated pulmonary dysfunction among mine workers

This study assessed the impact of silica exposure on 145 mine workers in Mianwali, Punjab, Pakistan, compared to 45 non-exposed individuals. Pulmonary function tests revealed significantly reduced lung function in exposed workers (P < 0.05), with declines in Forced Expiratory Volume in one second (FEV1), Forced Vital Capacity (FVC), FEV1/FVC ratio, Peak Expiratory Flow, and Forced Expiratory Flow at 25-75% of FVC (FEF25-75). Radiological evaluations confirmed extensive lung damage (P < 0.05), including pleural effusion, reticular shadowing, and lung consolidation. Oxidative stress markers demonstrated increased lipid peroxidation, Fenton's Oxidative Stress, and Oxidative Stress Index (P < 0.05), along with reduced antioxidant enzyme activities, including Catalase, Superoxide Dismutase, Total Antioxidant Capacity, and Glutathione Peroxidase. Hematological analysis showed elevated White Blood Cells, Lymphocyte percentage, Hemoglobin, Hematocrit, Mean Corpuscular Volume, and Mean Corpuscular Hemoglobin (P < 0.05), reflecting systemic inflammation. Silica's piezoelectric properties contributed to oxidative stress and cellular damage, exacerbating pulmonary dysfunction. These findings highlight silica exposure as a severe occupational hazard, causing irreversible lung impairment and systemic oxidative imbalance. Implementing strict safety protocols, personal protective measures, and regular health monitoring is crucial to safeguarding workers.

Inhalation of electronic cigarettes slightly affects lung function and inflammation in mice

Electronic cigarettes have become increasingly popular, but the results of previous studies on electronic cigarette exposure in animals have been equivocal. This study aimed to evaluate the effects of electronic cigarette smoke (ECS) and cigarette smoke (CS) on lung function and pulmonary inflammation in mice to investigate whether electronic cigarettes are safer when compared to cigarettes. 32 specific pathogen-free BALB/c male mice were randomly grouped and exposed to fresh air (control), mint-flavored ECS (ECS1, 6 mg/kg), cheese-flavored ECS (ECS2, 6 mg/kg), and CS (6 mg/kg). After 3 weeks exposure to ECS or CS, we measured lung function (PIF and Penh) and blood oxygen saturation. The levels of TNF-α and IL-6 in the bronchoalveolar lavage fluid (BALF) and serum were measured using ELISA. HE staining was performed to observe the pathological changes in the lung tissues. The levels of IL-6 in BALF and serum, and TNF-α in BALF, were elevated similarly in the ECS and CS groups compared to the control group. Significant elevation was observed in serum TNF-α levels in the CS group. The total count of cells in BALF were increased after ECS1 exposure and CS exposure. PIF and oxygen saturation decreased, and Penh increased markedly in the CS group but not in the ECS groups. Compared with the ECS groups, mice in the CS group had widened lung tissue septa and increased inflammatory cell infiltration. However, we did not detect significant differences between mint-flavored and cheese-flavored e-cigarettes in our study. Overall, our findings suggested that both ECS and CS impair lung function and histopathology while promoting inflammation. In contrast, ECS has a less negative impact than CS.

Macrophage Autophagy and Silicosis: Current Perspective and Latest Insights

Silicosis is an urgent public health problem in many countries. Alveolar macrophage (AM) plays an important role in silicosis progression. Autophagy is a balanced mechanism for regulating the cycle of synthesis and degradation of cellular components. Our previous study has shown that silica engulfment results in lysosomal rupture, which may lead to the accumulation of autophagosomes in AMs of human silicosis. The excessive accumulation of autophagosomes may lead to apoptosis in AMs. Herein, we addressed some assumptions concerning the complex function of autophagy-related proteins on the silicosis pathogenesis. We also recapped the molecular mechanism of several critical proteins targeting macrophage autophagy in the process of silicosis fibrosis. Furthermore, we summarized several exogenous chemicals that may cause an aggravation or alleviation for silica-induced pulmonary fibrosis by regulating AM autophagy. For example, lipopolysaccharides or nicotine may have a detrimental effect combined together with silica dust via exacerbating the blockade of AM autophagic degradation. Simultaneously, some natural product ingredients such as atractylenolide III, dioscin, or trehalose may be the potential AM autophagy regulators, protecting against silicosis fibrosis. In conclusion, the deeper molecular mechanism of these autophagy targets should be explored in order to provide feasible clues for silicosis therapy in the clinical setting.

Intranasal administration of budesonide-loaded nanocapsule microagglomerates as an innovative strategy for asthma treatment

The co-existence with rhinitis limits the control of asthma. Compared with oral H₁ receptor antagonists, intranasal corticosteroids have been demonstrated to provide greater relief of all symptoms of rhinitis and are recommended as first-line treatment for allergic rhinitis. Intrinsic limitations of nasal delivery, such as the presence of the protective mucous layer, the relentless mucociliary clearance, and the consequent reduced residence time of the formulation in the nasal cavity, limit budesonide efficacy to the treatment of local nasal symptoms. To overcome these limitations and to enable the treatment of asthma via nasal administration, we developed a budesonide-loaded lipid-core nanocapsule (BudNC) microagglomerate powder by spray-drying using a one-step innovative approach. BudNC was obtained, as a white powder, using L-leucine as adjuvant with 75 ± 6% yield. The powder showed a bimodal size distribution curve by laser diffraction with a principal peak just above 3 μm and a second one around 0.45 μm and a drug content determined by HPLC of 8.7 mg of budesonide per gram. In vivo after nasal administration, BudNC showed an improved efficacy in terms of reduction of immune cell influx; production of eotaxin-1, the main inflammatory chemokine; and arrest of airways remodeling when compared with a commercial budesonide product in both short- and long-term asthma models. In addition, data showed that the results in the long-term asthma model were more compelling than the results obtained in the short-term model. Graphical abstract.

Air pollution exposure and lung function in highly exposed subjects in Beijing, China: a repeated-measure study

Background

Exposure to ambient particulate matter (PM) has been associated with reduced lung function. Elemental components of PM have been suggested to have critical roles in PM toxicity, but their contribution to respiratory effects remains under-investigated. We evaluated the effects of traffic-related PM_2.5 and its elemental components on lung function in two highly exposed groups of healthy adults in Beijing, China.

Methods

The Beijing Truck Driver Air Pollution Study (BTDAS) included 60 truck drivers and 60 office workers evaluated in 2008. On two days separated by 1-2 weeks, we measured lung function at the end of the work day, personal PM_2.5, and nine elemental components of PM_2.5 during eight hours of work, i.e., elemental carbon (EC), potassium (K), sulfur (S), iron (Fe), silicon (Si), aluminum (Al), zinc (Zn), calcium (Ca), and titanium (Ti). We used covariate-adjusted mixed-effects models including PM_2.5 as a covariate to estimate the percentage change in lung function associated with an inter-quartile range (IQR) exposure increase.

Results

The two groups had high and overlapping exposure distributions with mean personal PM_2.5 of 94.6 μg/m³ (IQR: 48.5-126.6) in office workers and 126.8 μg/m³ (IQR: 73.9-160.5) in truck drivers. The distributions of the nine elements showed group-specific profiles and generally higher levels in truck drivers. In all subjects combined, forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) did not significantly correlate with PM_2.5. However, FEV1 showed negative associations with concentrations of four elements: Si (-3.07%, 95% CI: -5.00; -1.11, IQR: 1.54), Al (-2.88%, 95% CI: -4.91; -0.81, IQR: 0.86), Ca (-1.86%, 95% CI: -2.95; -0.76, IQR: 1.33), and Ti (-2.58%, 95% CI: -4.44; -0.68, IQR: 0.03), and FVC showed negative associations with concentrations of three elements: Si (-3.23%, 95% CI: -5.61; -0.79), Al (-3.26%, 95% CI: -5.73; -0.72), and Ca (-1.86%, 95% CI: -3.23; -0.47). In stratified analysis, Si, Al, Ca, and Ti showed associations with lung function only among truck drivers, and no significant association among office workers.

Conclusion

Selected elemental components of PM_2.5 showed effects on lung function that were not found in analyses of particle levels alone.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0051-7) contains supplementary material, which is available to authorized users.

Altered methylation in tandem repeat element and elemental component levels in inhalable air particles

Exposure to particulate matter (PM) has been associated with lung cancer risk in epidemiology investigations. Elemental components of PM have been suggested to have critical roles in PM toxicity, but the molecular mechanisms underlying their association with cancer risks remain poorly understood. DNA methylation has emerged as a promising biomarker for environmental-related diseases, including lung cancer. In this study, we evaluated the effects of PM elemental components on methylation of three tandem repeats in a highly exposed population in Beijing, China. The Beijing Truck Driver Air Pollution Study was conducted shortly before the 2008 Beijing Olympic Games (June 15-July 27, 2008) and included 60 truck drivers and 60 office workers. On two days separated by 1-2 weeks, we measured blood DNA methylation of SATα, NBL2, D4Z4, and personal exposure to eight elemental components in PM2.5 , including aluminum (Al), silicon (Si), sulfur (S), potassium (K), calcium (Ca) titanium (Ti), iron (Fe), and zinc (Zn). We estimated the associations of individual elemental component with each tandem-repeat methylation in generalized estimating equations (GEE) models adjusted for PM2.5 mass and other covariates. Out of the eight examined elements, NBL2 methylation was positively associated with concentrations of Si [0.121, 95% confidence interval (CI): 0.030; 0.212, False Discovery Rate (FDR) = 0.047] and Ca (0.065, 95%CI: 0.014; 0.115, FDR = 0.047) in truck drivers. In office workers, SATα methylation was positively associated with concentrations of S (0.115, 95% CI: 0.034; 0.196, FDR = 0.042). PM-associated differences in blood tandem-repeat methylation may help detect biological effects of the exposure and identify individuals who may eventually experience higher lung cancer risk.