Stress fibers, autophagy and necrosis by persistent exposure to PM2.5 from biomass combustion

Abstract

Fine particulate matter (PM2.5) can adversely affect human health. Emissions from residential energy sources have the largest impact on premature mortality globally, but their pathological and molecular implications on cellular physiology are still elusive. In the present study potential molecular consequences were investigated during long-term exposure of human bronchial epithelial BEAS-2B cells to PM2.5, collected from a biomass power plant. Initially, we observed that PM2.5 did not affect cellular survival or proliferation. However, it triggered an activation of the stress response p38 MAPK which, along with RhoA GTPase and HSP27, mediated morphological changes in BEAS-2B cells, including actin cytoskeletal rearrangements and paracellular gap formation. The p38 inhibitor SB203580 prevented phosphorylation of HSP27 and ameliorated morphological changes. During an intermediate phase of long-term exposure, PM2.5 triggered proliferative regression and activation of an adaptive stress response necessary to maintain energy homeostasis, including AMPK, repression of translational elongation, and autophagy. Finally, accumulation of intracellular PM2.5 promoted lysosomal destabilization and cell death, which was dependent on lysosomal hydrolases and p38 MAPK, but not on the inflammasome and pyroptosis. TEM images revealed formation of protrusions and cellular internalization of PM2.5, induction of autophagosomes, amphisomes, autophagosome-lysosomal fusion, multiple compartmental fusion, lysosomal burst, swollen mitochondria and finally necrosis. In consequence, persistent exposure to PM2.5 may impair epithelial barriers and reduce regenerative capacity. Hence, our results contribute to a better understanding of PM-associated lung and systemic diseases on the basis of molecular events.

Disease relevant modifications of the methylome and transcriptome by particulate matter (PM2.5) from biomass combustion

“…Gene ontology enrichment analysis revealed that hypomethylated genes prominently affected pathways involved in G-protein signaling, cellular structure and extracellular interaction. Correspondingly, we observed PM-dependent cytoskeletal changes, such as the formation of stress fibers, 20 which might progress to epithelial barrier disruption in the respiratory tract, systemic spread of inhaled particles and lung-independent diseases. Hypermethylated genes were also associated with pathways involving cellular adhesion, indicating that these pathways are a dominant field of epigenetic regulation by PM.…”

“…Mineralogical analysis revealed that the particles mainly consisted of crystalline arcanite (K 2 SO 4 ) or amorphous components (for detailed composition see Table S1 and Dornhof et al.). 20 …”

“…Preparation of PM 2.5 has been described previously. 20 Briefly, bulk fly ash was collected from an electrostatic precipitator of a medium-scale biomass power plant with a nominal thermal output of 1.7 MW (Bürger Energie St. Peter eG, St. Peter, Schwarzwald, Germany), which exclusively combusts chips of soft wood (mainly spruce) derived from the local forests. The wood chips included debarked stem wood and branches with a minimum of 7 cm in diameter (merchantable wood) without leaves and twigs.…”

Down-regulation of Fine Dusts-induced Airway Inflammation by the PDZ motif peptide of ZO-1

“…Recently, it was reported that although PM2.5 did not affect cellular survival or proliferation, PM2.5 activated the stress response mediated by p38 MAPK which, along with RhoA GTPase and HSP27, induced morphological changes, including actin cytoskeletal rearrangements and paracellular gap formation, in BEAS-2B cells [12]. Moreover, PM2.5 activated TGF-β1/SMAD3 signaling and α-SMA and COL1 upregulation in a human pulmonary fibroblast cell line (HFL-1), and triggered pulmonary fibrosis by targeting pulmonary epithelium, macrophages and fibroblasts [43]; however, no physiological mechanism by which PM affects F-actin polymerization, stress-fiber formation, and cytoskeletal rearrangements in airway epithelial cells has been reported.…”

Non-Canonical Binding of a Small Molecule to Sortilin Alters Cellular Trafficking of ApoB and PCSK9 in Liver Derived Cells

“…and Pepstatin) 31,32 , or HCQ (hydroxychloroquine) 33,34 , or left untreated. Autophagy activation was detected by presence or absence of LC3-II.…”