Low molecular weight-PAHs induced inflammation in A549 cells by activating PI3K/AKT and NF-κB signaling pathways

High molecular weight polycyclic aromatic hydrocarbon (HMW-PAH) isomers: unveiling distinct toxic effects from cytotoxicity to oxidative stress-induced DNA damage

Polycyclic aromatic hydrocarbons (PAHs) represent one of the most extensive classes of known carcinogenic and genotoxic compounds widely distributed across the globe. Particularly relevant to ecotoxicological studies is the possible presence of PAHs with molecular weight (MW) 302 Da. Since the toxicity of 302 Da PAHs differs significantly from isomer to isomer, understanding their relative toxicity is essential for assessing their potential risks to human health. This study investigates the toxic effects of micromolar concentrations of four HMW-PAHs isomers of MW = 302 Da, namely dibenzo(b,l)fluoranthene (DB(b,l)F), dibenzo(a,j)fluoranthene (DB(a,j)F), dibenzo(a,l)fluoranthene (DB(a,l)F) and naphtho(1-2j)fluoranthene (N(1-2j)F), upon exposure and metabolic activation in HepG2 cells. Appropriate assays were selected to investigate their potential to disrupt cellular viability and to induce cytotoxicity, apoptosis/necrosis, genotoxicity, and oxidative stress with DNA damage. After 48 h of exposure time, DB(a,l)F was the only isomer to reduce cellular viability in a concentration-dependent manner. In all cases, apoptosis was the main mechanism of HepG2 cell death, which could be induced by the significant DNA damage and an increase in 8-hydroxy-2'-deoxyguanosine (8-OHdG) adduct level formation. The highest concentrations of DB(a,l)F tested exhibited the greatest potential to induce HepG2 DNA damage and 8-OHdG formation. Altogether, these facts demonstrate that the distinct arrangements of the atoms in HMW-PAHs isomers can impact on their toxic potential and that DB(a,l)F was the most toxic isomer evaluated in this study. These results shed light on the importance to thoroughly characterize MW302 PAHs to substantiate their human and environmental risk assessments.

Chlorinated Anthracenes Induced Pulmonary Immunotoxicity in 3D Coculture Spheroids Simulating the Lung Microenvironment

Chlorinated anthracenes (Cl-Ants), persistent organic pollutants, are widely detected in the environment, posing potential lung toxicity risks due to frequent respiratory exposure. However, direct evidence and a comprehensive understanding of their toxicity mechanisms are lacking. Building on our prior findings of Cl-Ants' immunotoxic risks, this study developed a three-dimensional coculture spheroid model mimicking the lung's immune microenvironment. The objective is to explore the pulmonary immunotoxicity and comprehend its mechanisms, taking into account the heightened immune reactivity and frequent lung exposure of Cl-Ants. The results demonstrated that Cl-Ants exposure led to reduced spheroid size, increased macrophage migration outward, lowered cell viability, elevated 8-OHdG levels, disturbed anti-infection balance, and altered cytokine production. Specifically, the chlorine substituent number correlates with the extent of disruption of spheroid indicators caused by Cl-Ants, with stronger immunotoxic effects observed in dichlorinated Ant compared to those in monochlorinated Ant. Furthermore, we identified critical regulatory genes associated with cell viability (ALDOC and ALDOA), bacterial response (TLR5 and MAP2K6), and GM-CSF production (CEBPB). Overall, this study offers initial in vitro evidence of low-dose Cl-PAHs' pulmonary immunotoxicity, advancing the understanding of Cl-Ants' structure-related toxicity and improving external toxicity assessment methods for environmental pollutants, which holds significance for future monitoring and evaluation.

G-Protein Coupled Receptor 1 Is Involved in Tetrachlorobisphenol A-Induced Inflammatory Response in Jurkat Cells

Estrogens can affect the immune inflammatory response through estrogen receptor alpha (ERα), but the specific role of estrogen member receptor G-protein coupled receptor 1 (GPER1) in this process remains unclear. In this study, we evaluated the effects of tetrachlorobisphenol A (TCBPA), which has estrogen activity, on immune inflammatory-related indicators of Jurkat cells, as well as investigated the role of GPER1 in these effects. The results showed that TCBPA at lower concentrations significantly promoted the viability of Jurkat cells, whereas higher concentrations decreased cell viability. TCBPA at concentrations ranging from 1 to 25 μM increased the intracellular reactive oxygen species (ROS) levels. Additionally, treatment with 10 μM TCBPA increased the protein expression of ERα and GPER1, elevated the phosphorylation of protein kinase B (p-Akt), and upregulated the mRNA levels of GPER1, Akt, and phosphoinositide 3-kinase (PI3K) genes. Treatment with 10 μM TCBPA also upregulated the protein or gene expression of pro-inflammatory cytokines, such as interleukins (IL1β, IL2, IL6, IL8, IL12α) and tumor necrosis factor alpha (TNFα) in Jurkat cells. Furthermore, pretreatment with a GPER1 inhibitor G15 significantly reduced the mRNA levels of Akt induced by 10 μM TCBPA. Moreover, the upregulation of mRNA expression of RelA (p65), TNFα, IL6, IL8, and IL12α induced by 10 μM TCBPA was also significantly attenuated after G15 pretreatment. These findings suggest that TCBPA upregulates the expression of genes related to inflammatory responses by activating the GPER1-mediated PI3K/Akt signaling pathway. This study provides new insights into the mechanism of TCBPA-induced inflammatory response.

The key characteristics of cardiotoxicity for the pervasive pollutant phenanthrene

The key characteristic (KCs) framework has been used previously to assess the carcinogenicity and cardiotoxicity of various chemical and pharmacological agents. Here, the 12 KCs of cardiotoxicity are used to evaluate the previously reported cardiotoxicity of phenanthrene (Phe), a tricyclic polycyclic aromatic hydrocarbon (PAH), and major component of fossil fuel-derived air pollution. Phe is a semi-volatile pollutant existing in both the gas phase and particle phase through adsorption onto or into particulate matter (PM). Phe can translocate across the airways and gastrointestinal tract into the systemic circulation, enabling body-wide effects. Our evaluation based on a comprehensive literature review, indicates Phe exhibits 11 of the 12 KCs for cardiotoxicity. These include adverse effects on cardiac electromechanical performance, the vasculature and endothelium, immunomodulation and oxidative stress, and neuronal and endocrine control. Environmental agents that have similarly damaging effects on the cardiovascular system are heavily regulated and monitored, yet globally there is no air quality regulation specific for PAHs like Phe. Environmental monitoring of Phe is not the international standard with benzo[a]pyrene being frequently used as a proxy despite the two PAH species exhibiting significant differences in sources, concentration variations and toxic effects. The evidence summarised in this evaluation highlights the need to move away from proxied PAH measurements and develop a monitoring network capable of measuring Phe concentration. It also stresses the need to raise awareness amongst the medical community of the potential cardiovascular impact of PAH exposure. This will allow the production of mitigation strategies and possibly the development of new policies for the protection of the societal groups most vulnerable to cardiovascular disease.

Environmental pollutants and phosphoinositide signaling in autoimmunity

Environmental pollution stands as one of the most critical challenges affecting human health, with an estimated mortality rate linked to pollution-induced non-communicable diseases projected to range from 20% to 25%. These pollutants not only disrupt immune responses but can also trigger immunotoxicity. Phosphoinositide signaling, a pivotal regulator of immune responses, plays a central role in the development of autoimmune diseases and exhibits high sensitivity to environmental stressors. Among these stressors, environmental pollutants have become increasingly prevalent in our society, contributing to the initiation and exacerbation of autoimmune conditions. In this review, we summarize the intricate interplay between phosphoinositide signaling and autoimmune diseases within the context of environmental pollutants and contaminants. We provide an up-to-date overview of stress-induced phosphoinositide signaling, discuss 14 selected examples categorized into three groups of environmental pollutants and their connections to immune diseases, and shed light on the associated phosphoinositide signaling pathways. Through these discussions, this review advances our understanding of how phosphoinositide signaling influences the coordinated immune response to environmental stressors at a biological level. Furthermore, it offers valuable insights into potential research directions and therapeutic targets aimed at mitigating the impact of environmental pollutants on the pathogenesis of autoimmune diseases. SYNOPSIS: Phosphoinositide signaling at the intersection of environmental pollutants and autoimmunity provides novel insights for managing autoimmune diseases aggravated by pollutants.

Prenatal exposure to crude oil vapor reduces differentiation potential of rat fetal mesenchymal stem cells by regulating ERK1/2 and PI3K signaling pathways: Protective effect of quercetin

It has been indicated that crude oil vapor (COV) induces tissue damage by several molecular mechanisms. Quercetin (QT) as an important component of food with antioxidant properties has a protective role against cell toxicity caused by many pollutants. However, data related to the adverse effects of crude oil vapor (COV) on stem cell fate and differentiation and the role of quercetin (QT) in protecting stem cells against the toxicity caused by these pollutants is very limited. This study aimed to explore the protective effect of QT against the adverse effects of COV on fetal mesenchymal stem cells (fMSCs) differentiation. Twenty-four pregnant Wistar rats were categorized into 4 groups including the control, COV, COV+QT, and QT. Rats were exposed to COV from gestational day (GD) 0-15 and received QT by gavage. The fMSCs were isolated from fetuses, and cell proliferation, differentiation potential, expression of osteogenesis and adipogenesis-related genes, and phosphorylation of PI3K and ERK1/2 signaling proteins were evaluated. The results showed that COV reduced the proliferation and differentiation of fMSCs through the activation of PI3K and ERK1/2 signaling pathways. Also, COV significantly decreased the expression of osteonectin, ALP, BMP-6, Runx-2, PPARγ, and CREBBP genes in differentiated cells. QT treatment increased the proliferation and differentiation of fMSCs in COV-exposed rats. In conclusion, our findings suggest that prenatal exposure to COV impaired fMSCs differentiation and QT reduced the adverse effects of COV by regulating ERK1/2 and PI3K signaling pathways.

ROCK2-RNA interaction map reveals multiple biological mechanisms underlying tumor progression in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common form of kidney cancer in adults. Despite new therapeutic modalities, the outcomes for RCC patients remain unsatisfactory. Rho-associated coiled-coil forming protein kinase 2 (ROCK2) has previously been shown to be upregulated in RCC, and its expression was negatively correlated with patient survival. However, the precise molecular function of ROCK2 has remained unclear. Herein, using RNA-seq analysis of ROCK2 knockdown and control cells, we identified 464 differentially expressed genes, and 1287 alternative splicing events in 786-O RCC cells. Furthermore, mapping of iRIP-seq reads in 786-O cells showed a biased distribution at 5' UTR, intronic and intergenic regions. By comparing ROCK2-regulated alternative splicing and iRIP-seq data, we found 292 overlapping genes that are enriched in multiple tumorigenic pathways. Taken together, our work defined a complex ROCK2-RNA interaction map on a genomic scale in a human RCC cell line, which deepens our understanding of the molecular function of ROCK2 in cancer development.

Processing of carbon-reinforced construction materials releases PM2.5 inducing inflammation and (secondary) genotoxicity in human lung epithelial cells and fibroblasts

Building demolition following domestic fires or abrasive processing after thermal recycling can release particles harmful for the environment and human health. To mimic such situations, particles release during dry-cutting of construction materials was investigated. A reinforcement material consisting of carbon rods (CR), carbon concrete composite (C³) and thermally treated C³ (ttC³) were physicochemically and toxicologically analyzed in monocultured lung epithelial cells, and co-cultured lung epithelial cells and fibroblasts at the air-liquid interface. C³ particles reduced their diameter to WHO fibre dimensions during thermal treatment. Caused by physical properties or by polycyclic aromatic hydrocarbons and bisphenol A found in the materials, especially the released particles of CR and ttC³ induced an acute inflammatory response and (secondary) DNA damage. Transcriptome analysis indicated that CR and ttC³ particles carried out their toxicity via different mechanisms. While ttC³ affected pro-fibrotic pathways, CR was mostly involved in DNA damage response and in pro-oncogenic signaling.

Polycyclic aromatic hydrocarbons (PAHs): Updated aspects of their determination, kinetics in the human body, and toxicity

Polycyclic aromatic hydrocarbons (PAHs) are legacy pollutants of considerable public health concern. Polycyclic aromatic hydrocarbons arise from natural and anthropogenic sources and are ubiquitously present in the environment. Several PAHs are highly toxic to humans with associated carcinogenic and mutagenic properties. Further, more severe harmful effects on human- and environmental health have been attributed to the presence of high molecular weight (HMW) PAHs, that is PAHs with molecular mass greater than 300 Da. However, more research has been conducted using low molecular weight (LMW) PAHs). In addition, no HMW PAHs are on the priority pollutants list of the United States Environmental Protection Agency (US EPA), which is limited to only 16 PAHs. However, limited analytical methodologies for separating and determining HMW PAHs and their potential isomers and lack of readily available commercial standards make research with these compounds challenging. Since most of the PAH kinetic data originate from animal studies, our understanding of the effects of PAHs on humans is still minimal. In addition, current knowledge of toxic effects after exposure to PAHs may be underrepresented since most investigations focused on exposure to a single PAH. Currently, information on PAH mixtures is limited. Thus, this review aims to critically assess the current knowledge of PAH chemical properties, their kinetic disposition, and toxicity to humans. Further, future research needs to improve and provide the missing information and minimize PAH exposure to humans.

Novel mechanisms underlying inhibition of inflammation-induced angiogenesis by dexamethasone and gentamicin via PI3K/AKT/NF-κB/VEGF pathways in acute radiation proctitis

Acute radiation proctitis (ARP) is one of the most common complications of pelvic radiotherapy attributed to radiation exposure. The mechanisms of ARP are related to inflammation, angiogenesis, and so on. In this study we evaluated the effect of dexamethasone (DXM) combined with gentamicin (GM) enema on ARP mice, and explored its possible mechanisms by transcriptome sequencing, western blot and immunohistochemistry. C57BL/6 mice were randomly divided into 3 groups: healthy control group, ARP model group, and DXM + GM enema treatment group. ARP mice were established by using a single 6 MV X-ray dose of 27 Gy pelvic local irradiation. Transcriptome sequencing results showed that 979 genes were co-upregulated and 445 genes were co-downregulated in ARP mice compared to healthy mice. According to gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis, we firstly found that PI3K/AKT/NF-κB/VEGF pathways were mostly correlated with the inflammation-induced angiogenesis in ARP mice. PI3K/AKT pathway leads to the activation of NF-κB, which promotes the transcription of VEGF and Bcl-2. Interestingly, symptoms and pathological changes of ARP mice were ameliorated by DXM + GM enema treatment. DXM + GM enema inhibited inflammation by downregulating NF-κB and upregulating AQP3, as well as inhibited angiogenesis by downregulating VEGF and AQP1 in ARP mice. Moreover, DXM + GM enema induced apoptosis by increasing Bax and suppressing Bcl-2. The novel mechanisms may be related to the downregulation of PI3K/AKT/NF-κB/VEGF pathways.

The effect of low molecular weight-polycyclic aromatic hydrocarbons responsive hsa_circ_0039929/hsa-miR-15b-3p_R-1/FGF2 circuit on inflammatory response of A549 cells via the PI3K/AKT pathway and epithelial-mesenchymal transition process

Inflammation is widely recognized as an essential inducer of epithelial-mesenchymal transition (EMT). Meanwhile, competitive endogenous RNA (ceRNA) has been involved in a variety of disease processes. Therefore, the aim of the current study is to explore the regulation of ceRNA in the PI3K/AKT pathway and EMT mechanism in inflammatory response caused by low molecular weight-polycyclic aromatic hydrocarbons (LMW-PAHs). The A549 cells were treated with an equal mixture of phenanthrene (Phe) and fluorene (Flu), and total RNA was extracted for transcriptome sequencing. The target regulation of ceRNA hsa_circ_0039929/hsa-miR-15b-3p_R-1/FGF2 was further determined for mechanism study. The mixture of Phe and Flu significantly upregulated the expressions of hsa_circ_0039929 and FGF2, down-regulated hsa-miR-15b-3p_R-1, activated the PI3K/AKT pathway and promoted EMT. Mechanically, the overexpression of hsa-miR-15b-3p_R-1 inhibited the expressions of hsa_circ_0039929 and FGF2, reversed the activation of PI3K/AKT signaling pathway by LMW-PAHs, and blocked the occurrence of EMT progression. Furthermore, knockdown of hsa_circ_0039929 could promote the levels of hsa-miR-15b-3p_R-1, while inhibit the expression of FGF2. The effects of hsa_circ_0039929 knockdowns on PI3K/AKT pathways and EMT progress resembled the hsa-miR-15b-3p_R-1 overexpression. All above suggested that ceRNA hsa_circ_0039929/hsa-miR-15b-3p_R-1/FGF2 played an important role in the inflammation and EMT caused by LMW-PAHs.

Environmental dose of 16 priority-controlled PAHs mixture induce damages of vascular endothelial cells involved in oxidative stress and inflammation

Epidemiological studies have shown that cardiovascular diseases caused by PM_2.5 pollution account for the second death rate in China. Polycyclic aromatic hydrocarbons (PAHs) are one important group of persistent organic pollutants absorbed on PM_2.5. Though individual PAH is related to vascular disease, the relationship between environmental PAHs exposure and vascular damages is still unclear. To explore the effect of PAHs on blood vessel, human umbilical vein endothelial cells (HUVECs) are treated with 16 priority-controlled PAHs at various concentrations to study their cytotoxicity and morphological alteration. Results showed that, after 48 h treatment, PAHs mixture generally attenuated the ability of wound healing, transwell migration and tube formation of HUVECs (p < 0.01) except for 1 × PAHs in transwell migration. Moreover, PAHs increased the levels of ROS and 8-hydroxy-2'-deoxyguanosine (p < 0.05), indicating that it exceeded the scavenging ability of superoxide dismutase activity. However, PAHs mixture did not increase apoptosis rate, which may be attribute to the difference of PAH concentration and composition between this study and previous reports. Downstream signaling cascades significantly and generally upregulated the relative expression of proteins in Nrf2/HO-1 and NF-ƙB/TNF-α pathway with the activation of oxidative stress, including HO-, TNF-α and Nrf2. In summary, this study suggests that environmental mixture of 16 priority-controlled PAHs can induce the damages of vascular endothelial cells involved in cellular oxidative stress and inflammation.