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.

Short-term and residential exposure to air pollution: Associations with inflammatory biomarker levels in adults living in northern France

INTRODUCTION

Air pollution has an impact on health, and low-grade inflammation might be one of the underlying mechanisms. The objective of the present study of adults from northern France was to assess the associations between short-term and residential exposure to air pollution and levels of various inflammatory biomarkers.

METHODS

The cross-sectional Enquête Littoral Souffle Air Biologie Environnement (ELISABET) study was conducted from 2011 to 2013 in the Lille and Dunkirk urban areas of northern France. Here, we evaluated the associations between PM₁₀, NO₂ and O₃ exposure (on the day of the blood sample collection and on the day before, and the mean annual residential level) and levels of the inflammatory biomarkers high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-17A, IL-22, and tumor necrosis factor α.

RESULTS

We assessed 3074 participants for the association with hsCRP and a subsample of 982 non-smokers from Lille for the association with plasma cytokine levels. A 10 μg/m³ increment in PM₁₀ and NO₂ levels on the day of sample collection and on the day before was associated with a higher hsCRP concentration (3.43% [0.68; 6.25] and 1.75% [-1.96; 5.61], respectively, whereas a 10 μg/m³ increment in O₃ was associated with lower hsCRP concentration (-1.2% [-3.95; 1.64]). The associations between mean annual exposure and the hsCRP level were not significant. Likewise, the associations between exposure and plasma cytokine levels were not statistically significant.

CONCLUSION

Short-term exposure to air pollution was associated with higher serum hsCRP levels in adult residents of two urban areas in northern France. Our results suggest that along with other factors, low-grade inflammation might explain the harmful effects of air pollution on health.

Comparison of the in vivo genotoxicity of electronic and conventional cigarettes aerosols after subacute, subchronic and chronic exposures

Tobacco smoking is classified as a human carcinogen. A wide variety of new products, in particular electronic cigarettes (e-cigs), have recently appeared on the market as an alternative to smoking. Although the in vitro toxicity of e-cigs is relatively well known, there is currently a lack of data on their long-term health effects. In this context, the aim of our study was to compare, on a mouse model and using a nose-only exposure system, the in vivo genotoxic and mutagenic potential of e-cig aerosols tested at two power settings (18 W and 30 W) and conventional cigarette (3R4F) smoke. The standard comet assay, micronucleus test and Pig-a gene mutation assay were performed after subacute (4 days), subchronic (3 months) and chronic (6 months) exposure. The generation of oxidative stress was also assessed by measuring the 8-hydroxy-2'-deoxyguanosine and by using the hOGG1-modified comet assay. Our results show that only the high-power e-cig and the 3R4F cigarette induced oxidative DNA damage in the lung and the liver of exposed mice. In return, no significant increase in chromosomal aberrations or gene mutations were noted whatever the type of product. This study demonstrates that e-cigs, at high-power setting, should be considered, contrary to popular belief, as hazardous products in terms of genotoxicity in mouse model.

Toxicological appraisal of the chemical fractions of ambient fine (PM2.5-0.3) and quasi-ultrafine (PM0.3) particles in human bronchial epithelial BEAS-2B cells

New toxicological research is still urgently needed to improve the current knowledge about the induction of some underlying mechanisms of toxicity by the different chemical fractions of ambient particulate matter (PM). This in vitro study sought also to better evaluate and compare the respective toxicities of fine particles (PM_2.5-0.3) and their inorganic and organic chemical fractions, and the respective toxicities of the organic chemical fractions of PM_2.5-0.3 and quasi-ultrafine particles (PM_0.3). Human bronchial epithelial BEAS-2B cells were also exposed for 6-48 h to relatively low doses of PM_2.5-0.3 and their organic extractable (OEM_2.5-0.3) and non-extractable (NEM_2.5-0.3) fractions, and the organic extractable fraction (OEM_0.3) of PM_0.3. We reported that not only PM_2.5-0.3, but also, to a lesser extent, its inorganic chemical fraction, NEM_2.5-0.3, and organic chemical fraction, OEM_2.5-0.3, were able to significantly induce ROS overproduction and oxidative damage notwithstanding the early activation of NRF2 signaling pathway. Moreover, for any exposure, inflammatory and apoptotic events were noticed. Similar results were observed in BEAS-2B cells exposed to OEM_0.3, rich of polycyclic aromatic hydrocarbons and their nitrated and oxygenated derivatives. In BEAS-2B cells exposed for 24 and 48 h to OEM_2.5-0.3 and OEM_0.3, to a higher extent, there was an alteration of the levels of some critical proteins even though crucial for the autophagy rather than a real reduction of autophagy. It is noteworthy that the toxicological effects were equal or mostly higher in BEAS-2B cells exposed for 6 and/or 24 h to PM_2.5-0.3 from those exposed to NEM_2.5-0.3 or OEM_2.5-0.3, and in BEAS-2B cells exposed for 6 and/or mostly 24 h to OEM_0.3 from those exposed to OEM_2.5-0.3. Taken together, these results revealed the higher potentials for toxicity, closely linked to their respective physical and chemical characteristics, of PM_2.5-0.3 vs NEM_2.5-0.3 and/or OEM_2.5-0.3, and OEM_0.3 vs OEM_2.5-0.3.

Toxicity of fine and quasi-ultrafine particles: Focus on the effects of organic extractable and non-extractable matter fractions

To date no study has been able to clearly attribute the observed toxicological effects of atmospheric particles (PM) to a specific class of components. The toxicity of both the organic extractable matter (OEM_2.5-0.3) and non-extractable matter (NEM_2.5-0.3) of fine particles (PM_2.5-0.3) was compared to that of PM_2.5-0.3 in its entirety on normal human epithelial bronchial BEAS-2B cells in culture. The specific effect of the quasi-ultrafine fraction (PM_0.3) was assessed, by comparing the responses of cells exposed to the PM_2.5-0.3 and PM_0.3 organic extractable matter, OEM_2.5-0.3 and OEM_0.3 respectively. Chemically, PAH, O-PAH, and N-PAH were respectively 43, 17, and 4 times more concentrated in PM_0.3 than in PM_2.5-0.3, suggesting thereby a predominant influence of anthropogenic activities and combustion sources. BEAS-2B cells exposed to PM_2.5-0.3, NEM_2.5-0.3, EOM_2.5-0.3 and OEM_0.3 lead to different profiles of expression of selected genes and proteins involved in the metabolic activation of PAH, O-PAH, and N-PAH, and in the genotoxicity pathways. Specifically, OEM_0.3 was the most inducer for phase I and phase II enzymes implicated in the metabolic activation of PAH (AHR, AHRR, ARNT, CYP1A1, CYP1B1, EPHX-1, GSTA-4) thereby producing the highest DNA damage, felt by ATR and, thereafter, a cascade of protein phosphorylation (CHK1/CHK2/MDM2) closely related to the cell cycle arrest (P21 and P53 induction). This study underlined the crucial role played by the organic chemicals present in PM_0.3. These results should be considered in any future study looking for the main chemical determinants responsible for the toxicity of ambient fine PM.

In vitro evaluation of organic extractable matter from ambient PM2.5 using human bronchial epithelial BEAS-2B cells: Cytotoxicity, oxidative stress, pro-inflammatory response, genotoxicity, and cell cycle deregulation

A particular attention has been devoted to the type of toxicological responses induced by particulate matter (PM), since their knowledge is greatly complicated by the fact that it is a heterogeneous and often poorly described pollutant. However, despite intensive research effort, there is still a lack of knowledge about the specific chemical fraction of PM, which could be mainly responsible of its adverse health effects. We sought also to better investigate the toxicological effects of organic extractable matter (OEM) in normal human bronchial epithelial lung BEAS-2B cells. The wide variety of chemicals, including PAH and other related-chemicals, found in OEM, has been rather associated with early oxidative events, as supported by the early activation of the sensible NRF-2 signaling pathway. For the most harmful conditions, the activation of this signaling pathway could not totally counteract the ROS overproduction, thereby leading to critical oxidative damage to macromolecules (lipid peroxidation, oxidative DNA adducts). While NRF-2 is an anti-inflammatory, OEM exposure did not trigger any significant change in the secretion of inflammatory cytokines (i.e., TNFα, IL-1β, IL-6, IL-8, MCP-1, and IFNγ). According to the high concentrations of PAH and other related organic chemicals found in this OEM, CYP1A1 and 1B1 genes exhibited high transcription levels in BEAS-2B cells, thereby supporting both the activation of the critical AhR signaling pathway and the formation of highly reactive ultimate metabolites. As a consequence, genotoxic events occurred in BEAS-2B cells exposed to this OEM together with cell survival events, with possible harmful cell cycle deregulation. However, more studies are required to implement these observations and to contribute to better decipher the critical role of the organic fraction of air pollution-derived PM_2.5 in the activation of some sensitive signaling pathways closely associated with G1/S and intra-S checkpoint blockage, on the one hand, and cell survival, on the other hand.

Reduced maternal behavior caused by gestational stress is predictive of life span changes in risk-taking behavior and gene expression due to altering of the stress/anti-stress balance

Exposure of the mother to adverse events during pregnancy is known to induce pathological programming of the HPA axis in the progeny, thereby increasing the vulnerability to neurobehavioral disorders. Maternal care plays a crucial role in the programming of the offspring, and oxytocin plays a key role in mother/pup interaction. Therefore, we investigated whether positive modulation of maternal behavior by activation of the oxytocinergic system could reverse the long-term alterations induced by perinatal stress (PRS; gestational restraint stress 3 times/day during the last ten days of gestation) on HPA axis activity, risk-taking behavior in the elevated-plus maze, hippocampal mGlu5 receptor and gene expression in Sprague-Dawley rats. Stressed and control unstressed dams were treated during the first postpartum week with an oxytocin receptor agonist, carbetocin (1 mg/kg, i.p.). Remarkably, reduction of maternal behavior was predictive of behavioral disturbances in PRS rats as well as of the impairment of the oxytocin and its receptor gene expression. Postpartum carbetocin corrected the reduction of maternal behavior induced by gestational stress as well as the impaired oxytocinergic system in the PRS progeny, which was associated with reduced risk-taking behavior. Moreover, postpartum carbetocin had an anti-stress effect on HPA axis activity in the adult PRS progeny and increased hippocampal mGlu5 receptor expression in aging. In conclusion, the activation of the oxytocinergic system in the early life plays a protective role against the programming effect by adverse experiences and could be considered as a novel and powerful potential therapeutic target for stress-related disorders.