Metal enriched quasi-ultrafine particles from stainless steel gas metal arc welding induced genetic and epigenetic alterations in BEAS-2B cells

Experimental factors influencing the bioaccessibility and the oxidative potential of transition metals from welding fumes

Inhalation of welding fumes (WFs) containing high levels of transition metals (Cr, Cu, Fe, Mn, Ni…) is associated with numerous health effects including oxidative stress. However, the measurements of the oxidative potential (OP) and bioaccessibility of WF transition metals depend on several physicochemical parameters and may be subject to several experimental artifacts. In this work, we investigated the influence of the experimental conditions that may affect the bioaccessibility of transition metals and their OP on stainless-steel WF extracts. WFs were produced using a generation bench and sampled on filters. The soluble fraction of the metals was analysed. Two different extraction fluids mimicking physiological pulmonary conditions were studied: phosphate buffer and Hatch's solution. Three extraction times were tested to determine the optimal time for a significant OPDTT using the dithiothreitol (DTT) method. The storage conditions of WFs after filter sampling such as duration, temperature and atmospheric conditions were investigated. The results indicate that experimental conditions can significantly affect the OPDTT and metal bioaccessibility analyses. Cr, Cu and Ni show higher solubility in Hatch's solution than in the phosphate buffer. Mn is highly sensitive to DTT and shows close solubility in the two fluids. An extraction time of 0.5 h in phosphate buffer allows a better sensitivity to OPDTT, probably by limiting complexations, interactions between metals and precipitation. Storage time and temperature can influence the physical or chemical evolution of the WFs, which can affect their OPDTT and Mn solubility. However, storage under N2(g) limits these changes. On-line measurements of OPDTT could provide an alternative to filter sampling to overcome these artifacts.

Difference in the cellular response following THP-1 derived phagocytic monocyte cells exposure to commercial aluminum-based adjuvants and aluminum-containing vaccines

BACKGROUND

Aluminum-based adjuvants (ABAs) enhance the immune response following vaccine injection. Their mechanisms of action are not fully understood, and their bio-persistency have been described associated with long-term adverse effects.

METHODS

We evaluated and compared the cellular effects of the two main ABAs and whole vaccines on ATP production, ROS generation and cytokines production (IL-6 and IL-10), using THP-1 cells.

RESULTS

ABAs altered the cell energy metabolism by increasing ROS production after 24 h and reducing ATP production after 48 h. In addition, both ABAs and whole vaccines induced different kinetics of IL-6 production, whereas only ABAs induced IL-10 secretion.

CONCLUSION

This study showed clearly, for a first time, a difference in cellular response to the ABAs and whole vaccines which should be taken into consideration in future studies focusing on the effect of ABA in vaccines. Future studies on ABAs should also pay attention to mitochondrial function alterations following exposure to ABA-containing vaccines.

Oxidative stress and inflammation induced by air pollution-derived PM2.5 persist in the lungs of mice after cessation of their sub-chronic exposure

More than 7 million early deaths/year are attributable to air pollution. Current health concerns are especially focused on air pollution-derived particulate matter (PM). Although oxidative stress-induced airway inflammation is one of the main adverse outcome pathways triggered by air pollution-derived PM, the persistence of both these underlying mechanisms, even after exposure cessation, remained poorly studied. In this study, A/JOlaHsd mice were also exposed acutely (24 h) or sub-chronically (4 weeks), with or without a recovery period (12 weeks), to two urban PM2.5 samples collected during contrasting seasons (i.e., autumn/winter, AW or spring/summer, SS). The distinct intrinsic oxidative potentials (OPs) of AW and SS PM2.5, as evaluated in acellular conditions, were closely related to their respective physicochemical characteristics and their respective ability to really generate ROS over-production in the mouse lungs. Despite the early activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) cell signaling pathway by AW and, in a lesser degree, SS PM2.5, in the murine lungs after acute and sub-chronic exposures, the critical redox homeostasis was not restored, even after the exposure cessation. Accordingly, an inflammatory response was reported through the activation of the nuclear factor-kappa B (NF-κB) cell signaling pathway activation, the secretion of cytokines, and the recruitment of inflammatory cells, in the murine lungs after the acute and sub-chronic exposures to AW and, in a lesser extent, to SS PM2.5, which persisted after the recovery period. Taken together, these original results provided, for the first time, new relevant insights that air pollution-derived PM2.5, with relatively high intrinsic OPs, induced oxidative stress and inflammation, which persisted admittedly at a lower level in the lungs after the exposure cessation, thereby contributing to the occurrence of molecular and cellular adverse events leading to the development and/or exacerbation of future chronic inflammatory lung diseases and even cancers.

ACSL4 and the lipoxygenases 15/15B are pivotal for ferroptosis induced by iron and PUFA dyshomeostasis in dopaminergic neurons

Ferroptosis, an iron-dependent regulated cell death triggered by high lipid peroxide levels, has been implicated in several neurodegenerative diseases, including Parkinson's disease (PD). Brain regions such as the striatum are highly rich in both peroxidation susceptible PUFAs and iron, which accumulate at a greater rate than age in PD. The exact molecular pathways and patho-physiological conditions promoting cell death in the dopaminergic neurons that are particularly susceptible in PD remain elusive. In the current work, we show that modifying the PUFA composition in membranes of dopaminergic neurons using arachidonic acid (AA) can determine ferroptosis susceptibility. Furthermore, cotreatment with iron (Fe), increases AA-containing phospholipid association and synergistically promotes high lipid peroxidation to facilitate ferroptosis. Ex vivo analysis with organotypic brain slices, confirm that AA + Fe induces cell death in the nigrostriatal pathway and can be rescued by the anti-ferroptotic drug Ferrostatin-1. Prevention of ferroptotic AA + Fe induced cell death through inhibition of ACSL4, ALOX15 or ALOX15B provides mechanistic support of this lipid peroxidation pathway being involved in dopaminergic neuronal death and novel potential pharmacological targets for neuroprotective strategies in PD.