Extracellular Histones Promote Pulmonary Fibrosis in Patients With Coal Workers' Pneumoconiosis

Characterization and Toxicity Analysis of Lab-Created Respirable Coal Mine Dust from the Appalachians and Rocky Mountains Regions

Coal mine workers are continuously exposed to respirable coal mine dust (RCMD) in workplaces, causing severe lung diseases. RCMD characteristics and their relations with dust toxicity need further research to understand the adverse exposure effects to RCMD. The geographic clustering of coal workers’ pneumoconiosis (CWP) suggests that RCMD in the Appalachian region may exhibit more toxicity than other geographic regions such as the Rocky Mountains. This study investigates the RCMD characteristics and toxicity based on geographic location. Dissolution experiments in simulated lung fluids (SLFs) and in vitro responses were conducted to determine the toxicity level of samples collected from five mines in the Rocky Mountains and Appalachian regions. Dust characteristics were investigated using Fourier-transform infrared spectroscopy, scanning electron microscopy, the BET method, total microwave digestion, X-ray diffraction, and X-ray photoelectron spectroscopy. Inductively coupled plasma mass spectrometry was conducted to determine the concentration of metals dissolved in the SLFs. Finer particle sizes and higher mineral and elemental contents were found in samples from the Appalachian regions. Si, Al, Fe, Cu, Sr, and Pb were found in dissolution experiments, but no trends were found indicating higher dissolutions in the Appalachian region. In vitro studies indicated a proinflammatory response in epithelial and macrophage cells, suggesting their possible participation in pneumoconiosis and lung diseases development.

Elucidation of alveolar macrophage cell response to coal dusts: Role of ferroptosis in pathogenesis of coal workers' pneumoconiosis

Causal factors underlying coal workers' pneumoconiosis (CWP) have been variously attributed to the presence of carbon, crystalline silica and reduced iron (Fe) minerals, especially pyrite and Fe/Si-amorphous compounds. The aim of this research was to assess the role of iron in CWP and, more specifically, the cytotoxicity of coal dusts with different elemental composition towards alveolar macrophages (AMs). Survival rate of AMs, alteration in the production of pro-inflammatory cytokine TNF-α, MDA (the lipid peroxidation product) and intracellular GSH were assessed using commercial assay kits. The quantitative interaction between iron and GSH was investigated by developing a numerical model. The presence of various reduced Fe minerals (viz. pyrite and siderite) in coal dusts exhibited a consistently acute adverse impact on the viability of AMs and enhanced the production of TNF-α. The presence of the clinically available Fe chelator deferiprone (DFP) and the cytosolic antioxidant glutathione (GSH) significantly increased the viability of AMs exposed to Fe bearing coal dusts, suggesting coal dusts containing reduced Fe minerals were likely contributors to the initial stages of AM cytotoxicity via a ferroptosis related pathway. Chemical kinetic modeling indicated that these results may be attributed to an enhanced consumption of GSH as a result of Fe redox cycling. Fe^IIGSH and GS^• produced from the interaction between ferric Fe and GSH facilitated the production of O₂^•- which further oxidized GSH via a direct reaction between GSH and GS^• or GSO^•. These results suggest that coal dusts containing reduced Fe minerals and Fe compounds may elevate acute inflammation levels in AMs, indicating that crystalline silica may not be the only hazard of concern in mining environments.

Impact of reactive iron in coal mine dust on oxidant generation and epithelial lung cell viability

Coal workers' pneumoconiosis (CWP) is a preventable occupational lung disease caused by the chronic inhalation of coal mine dust. The inhalation of coal mine dusts can result in the development of a range of lung diseases termed coal mine dust lung diseases, which is not limited to CWP and includes silicosis, bronchitis, emphysema and cancer. For decades, the presence of elemental Fe, C and Si has been proposed to be the causal factors underlying CWP. The recent resurgence of CWP globally with examination of cases in the United States suggesting a potential but inconclusive role of Fe(II)-sulfide minerals. To obtain a better understanding of Australian coals, the existence and potential adverse impacts of iron minerals were examined using 24 representative Australian coal samples. The results of this work revealed that reduced iron minerals were widely distributed within samples obtained from Australian coal mines with pyrite and siderite being particularly abundant. Compared with carbon and crystalline silica, the presence of these specific iron minerals were negatively correlated to the viability of both alveolar macrophages (NR8383) and human lung epithelial cells (A549) (R² = 0.689) under scenarios reflecting biologically-relevant inflammatory response conditions. Further analysis using Welch's unpaired t-test indicated that the presence of reduced iron minerals statistically enhanced acellular oxidant production (90% CI [0.74 to 2.55]) and inflammatory response (90% CI [0.15 to 36.96]). Compared with Fe(II)-hydroxide, Fe(II)- and Fe(III)-(phyllo)silicate and Fe(II)-sulfate mineralogies, pyrite and siderite bearing dusts are likely to have greater adverse impacts on epithelial lung cells under inflammatory response conditions in view of both their iron content and reactivity.

p53: A Key Protein That Regulates Pulmonary Fibrosis

Pulmonary fibrosis is a progressively aggravating lethal disease that is a serious public health concern. Although the incidence of this disease is increasing, there is a lack of effective therapies. In recent years, the pathogenesis of pulmonary fibrosis has become a research hotspot. p53 is a tumor suppressor gene with crucial roles in cell cycle, apoptosis, tumorigenesis, and malignant transformation. Previous studies on p53 have predominantly focused on its role in neoplastic disease. Following in-depth investigation, several studies have linked it to pulmonary fibrosis. This review covers the association between p53 and pulmonary fibrosis, with the aim of providing novel ideas to improve the clinical diagnosis, treatment, and prognosis of pulmonary fibrosis.