More than a cell biosensor: aryl hydrocarbon receptor at the intersection of physiology and inflammation

Association between polycyclic aromatic hydrocarbons and periodontitis: Results from a large population-based study

AIM

To explore the association between polycyclic aromatic hydrocarbons (PAHs) (measured using urinary metabolites) and periodontitis using data from the National Health and Nutrition Examination Survey 2009-2014.

MATERIALS AND METHODS

Weighted binary logistic regression, Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression were used to evaluate independent and joint associations between the six urinary monohydroxylated metabolites of PAHs (OH-PAHs) and periodontitis.

RESULTS

In all, 3413 participants were included in this study. All six urinary OH-PAHs were present at higher levels in the periodontitis group compared with the non-periodontitis group (p < .001). Fully adjusted multivariable logistic regressions showed positive associations between the six urinary OH-PAHs and periodontitis (p < .05). Higher concentrations of OH-PAHs were also positively associated with attachment loss, periodontal pocket depth (PPD) and the number of tooth loss. BKMR and WQS regression yielded similar positive associations between OH-PAH mixtures and periodontitis.

CONCLUSIONS

PAHs and their mixture are positively associated with periodontitis, which may provide novel insights into periodontitis prevention from an environmental exposure perspective.

Effects of PM10 Airborne Particles from Different Regions of a Megacity on In Vitro Secretion of Cytokines by a Monocyte Line during Different Seasons

Several epidemiological studies have demonstrated that particulate matter (PM) in air pollution can be involved in the genesis or aggravation of different cardiovascular, respiratory, perinatal, and cancer diseases. This study assessed the in vitro effects of PM10 on the secretion of cytokines by a human monocytic cell line (THP-1). We compared the chemotactic, pro-inflammatory, and anti-inflammatory cytokines induced by PM10 collected for two years during three different seasons in five different Mexico City locations. MIP-1α, IP-10, MCP-1, TNF-α, and VEGF were the main secretion products after stimulation with 80 μg/mL of PM10 for 24 h. The THP-1 cells showed a differential response to PM10 obtained in the different sites of Mexico City. The PM10 from the north and the central city areas induced a higher pro-inflammatory cytokine response than those from the south. Seasonal pro-inflammatory cytokine secretion always exceeded anti-inflammatory secretion. The rainy-season-derived particles caused the lowest pro-inflammatory effects. We concluded that toxicological assessment of airborne particles provides evidence supporting their potential role in the chronic exacerbation of local or systemic inflammatory responses that may worsen the evolution of some chronic diseases.

Advancing biological investigations using portable sensors for detection of sensitive samples

Portable biosensors are emerged as powerful diagnostic tools for analyzing intricately complex biological samples. These biosensors offer sensitive detection capabilities by utilizing biomolecules such as proteins, nucleic acids, microbes or microbial products, antibodies, and enzymes. Their speed, accuracy, stability, specificity, and low cost make them indispensable in forensic investigations and criminal cases. Notably, portable biosensors have been developed to rapidly detect toxins, poisons, body fluids, and explosives; they have proven invaluable in forensic examinations of suspected samples, generating efficient results that enable effective and fair trials. One of the key advantages of portable biosensors is their ability to provide sensitive and non-destructive detection of forensic samples without requiring extensive sample preparation, thereby reducing the possibility of false results. This comprehensive review provides an overview of the current advancements in portable biosensors for the detection of sensitive materials, highlighting their significance in advancing investigations and enhancing sensitive sample detection capabilities.

Mechanisms of breast cancer progression induced by environment-polluting aryl hydrocarbon receptor agonists

Breast cancer is the most common invasive malignancy among women worldwide and constitutes a complex and heterogeneous disease. Interest has recently grown in the role of the aryl hydrocarbon receptor (AhR) in breast cancer and the contribution of environment-polluting AhR agonists. Here, we present a literature review addressing AhR ligands, including pesticides hexachlorobenzene and chlorpyrifos, polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, parabens, and phthalates. The objectives of this review are a) to summarize recent original experimental, preclinical, and clinical studies on the biological mechanisms of AhR agonists which interfere with the regulation of breast endocrine functions, and b) to examine the biological effects of AhR ligands and their impact on breast cancer development and progression. We discuss biological mechanisms of action in cell viability, cell cycle, proliferation, epigenetic changes, epithelial to mesenchymal transition, and cell migration and invasion. In addition, we examine the effects of AhR ligands on angiogenic processes, metastasis, chemoresistance, and stem cell renewal. We conclude that exposure to AhR agonists stimulates pathways that promote breast cancer development and may contribute to tumor progression. Given the massive use of industrial and agricultural chemicals, ongoing evaluation of their effects in laboratory assays and preclinical studies in breast cancer at environmentally relevant doses is deemed essential. Likewise, awareness should be raised in the population regarding the most harmful toxicants to eradicate or minimize their use.

Bojungikgi-tang improves skin barrier function and immune response in atopic dermatitis mice fed a low aryl hydrocarbon receptor ligand diet

BACKGROUND

The aryl hydrocarbon receptor (AhR) is a transcription factor that plays a crucial role in regulating the immune system and maintaining skin barrier function. AhR signaling is pivotal in the pathogenesis of inflammatory diseases such as atopic dermatitis (AD), and the absence of AhR ligands further contributes to the progression or worsening of AD symptoms.

METHODS

AD was induced with 2,4-dinitrochlorobenzene (DNCB), and Bojungikgi-tang (BJIKT) was administered orally daily for 10 weeks. Serum IgE, splenocyte IL-4, and IFN-γ levels, skin barrier genes, and AhR target gene expressions were analyzed using RNA-sequencing analysis. Spleen tissues were extracted for fluorescence-activated cell sorting (FACS) analysis to analyze the effect of BJIKT on immune responses. A correlation analysis was conducted to analyze the correlation between immune markers and skin barrier genes and AhR target genes.

RESULTS

BJIKT effectively improved AD symptoms in AD mice fed a low AhR ligand diet by reducing neutrophil and eosinophil counts, lowering IgE levels in the blood, and decreasing IL-4 and IFN-γ levels in the splenocytes. Additionally, BJIKT significantly reduced epithelial skin thickness and transepidermal water loss (TEWL) values and reversed the decreased expression of skin barrier genes. BJIKT also considerably altered the expression of AhR target genes, including Ahr, Ahrr, cytochrome P450 1A1 (CYP1A1), and CYP1B1. Furthermore, AhR target pathway genes were negatively correlated with immune cell subtypes, including CD4 + and CD8 + T cells and macrophages (CD11b + F4/80 +) at the systemic level.

CONCLUSIONS

BJIKT can regulate AhR activation and may help reduce inflammation in AD by regulating the expression of skin barrier genes and immune responses.

Long COVID as a Tauopathy: Of "Brain Fog" and "Fusogen Storms"

Long COVID, also called post-acute sequelae of SARS-CoV-2, is characterized by a multitude of lingering symptoms, including impaired cognition, that can last for many months. This symptom, often called "brain fog", affects the life quality of numerous individuals, increasing medical complications as well as healthcare expenditures. The etiopathogenesis of SARS-CoV-2-induced cognitive deficit is unclear, but the most likely cause is chronic inflammation maintained by a viral remnant thriving in select body reservoirs. These viral sanctuaries are likely comprised of fused, senescent cells, including microglia and astrocytes, that the pathogen can convert into neurotoxic phenotypes. Moreover, as the enteric nervous system contains neurons and glia, the virus likely lingers in the gastrointestinal tract as well, accounting for the intestinal symptoms of long COVID. Fusogens are proteins that can overcome the repulsive forces between cell membranes, allowing the virus to coalesce with host cells and enter the cytoplasm. In the intracellular compartment, the pathogen hijacks the actin cytoskeleton, fusing host cells with each other and engendering pathological syncytia. Cell-cell fusion enables the virus to infect the healthy neighboring cells. We surmise that syncytia formation drives cognitive impairment by facilitating the "seeding" of hyperphosphorylated Tau, documented in COVID-19. In our previous work, we hypothesized that the SARS-CoV-2 virus induces premature endothelial senescence, increasing the permeability of the intestinal and blood-brain barrier. This enables the migration of gastrointestinal tract microbes and/or their components into the host circulation, eventually reaching the brain where they may induce cognitive dysfunction. For example, translocated lipopolysaccharides or microbial DNA can induce Tau hyperphosphorylation, likely accounting for memory problems. In this perspective article, we examine the pathogenetic mechanisms and potential biomarkers of long COVID, including microbial cell-free DNA, interleukin 22, and phosphorylated Tau, as well as the beneficial effect of transcutaneous vagal nerve stimulation.

Identification of Methylsulochrin as a Partial Agonist for Aryl Hydrocarbon Receptors and Its Antiviral and Anti-inflammatory Activities

Although aryl hydrocarbon receptors (AhRs) are related to the metabolic pathway of xenobiotics, recent studies have revealed that this receptor is also associated with the life cycle of viruses and inflammatory reactions. For example, flutamide, used to treat prostate cancer, inhibits hepatitis C virus proliferation by acting as an AhR antagonist, and methylated-pelargonidin, an AhR agonist, suppresses pro-inflammatory cytokine production. To discover a novel class of AhR ligands, we screened 1000 compounds derived from fungal metabolites using a reporter assay and identified methylsulochrin as a partial agonist of the aryl hydrocarbon receptor. Methylsulochrin was found to inhibit the production of hepatitis C virus (HCV) in Huh-7.5.1 cells. Methylsulochrin also suppressed the production of interleukin-6 in RAW264.7 cells. Furthermore, a preliminary structure-activity relationship study using sulochrin derivatives was performed. Our findings suggest the use of methylsulochrin derivatives as anti-HCV compounds with anti-inflammatory activity.

Vitamins, microelements and the immune system: current standpoint in the fight against coronavirus disease 2019

Coronavirus disease 2019 (COVID-19) is an acute respiratory disease associated with severe systemic inflammation. The optimal status of vitamins and microelements is considered crucial for the proper functioning of the immune system and necessary for successful recovery. Most patients with respiratory distress in COVID-19 are vitamin and microelement deficient, with vitamin D and Se deficiency being the most common. Anyway, various micronutrient supplements are widely and arbitrarily used for prevention or in the treatment of COVID-19. We aimed to summarise current knowledge about molecular and physiological mechanisms of vitamins (D, A, C, B₆, B₉ and B₁₂) and microelements (Se, Zn, Cu and Fe) involved in the immune system regulation in consideration with COVID-19 pathogenesis, as well as recent findings related to their usage and effects in the prevention and treatment of COVID-19. In the early course of the pandemic, several, mainly observational, studies reported an association of some micronutrients, such as vitamin C, D and Zn, with severity reduction and survival improvement. Still, emerging randomised controlled trials showed no effect of vitamin D on hospitalisation length and no effect of vitamin C and Zn on symptom reduction. Up to date, there is evidence neither for nor against the use of micronutrients in the treatment of COVID-19. The doses that exceed the recommended for the general population and age group should not be used, except in clinical trials. Benefits of supplementation are primarily expected in populations prone to micronutrient deficiencies, who are, as well, at a higher risk of worse outcomes in COVID-19.

CYP1A1, VEGFA and Adipokine Responses of Human Adipocytes Co-exposed to PCB126 and Hypoxia

It is increasingly recognized that hypoxia may develop in adipose tissue as its mass expands. Adipose tissue is also the main reservoir of lipophilic pollutants, including polychlorinated biphenyls (PCBs). Both hypoxia and PCBs have been shown to alter adipose tissue functions. The signaling pathways induced by hypoxia and pollutants may crosstalk, as they share a common transcription factor: aryl hydrocarbon receptor nuclear translocator (ARNT). Whether hypoxia and PCBs crosstalk and affect adipokine secretion in human adipocytes remains to be explored. Using primary human adipocytes acutely co-exposed to different levels of hypoxia (24 h) and PCB126 (48 h), we observed that hypoxia significantly inhibits the PCB126 induction of cytochrome P450 (CYP1A1) transcription in a dose-response manner, and that Acriflavine (ACF)—an HIF1α inhibitor—partially restores the PCB126 induction of CYP1A1 under hypoxia. On the other hand, exposure to PCB126 did not affect the transcription of the vascular endothelial growth factor-A (VEGFA) under hypoxia. Exposure to hypoxia increased leptin and interleukin-6 (IL-6), and decreased adiponectin levels dose-dependently, while PCB126 increased IL-6 and IL-8 secretion in a dose-dependent manner. Co-exposure to PCB126 and hypoxia did not alter the adipokine secretion pattern observed under hypoxia and PCB126 exposure alone. In conclusion, our results indicate that (1) hypoxia inhibits PCB126-induced CYP1A1 expression at least partly through ARNT-dependent means, suggesting that hypoxia could affect PCB metabolism and toxicity in adipose tissue, and (2) hypoxia and PCB126 affect leptin, adiponectin, IL-6 and IL-8 secretion differently, with no apparent crosstalk between the two factors.

Aryl Hydrocarbon Receptor in Oxidative Stress as a Double Agent and Its Biological and Therapeutic Significance

The aryl hydrocarbon receptor (AhR) has long been implicated in the induction of a battery of genes involved in the metabolism of xenobiotics and endogenous compounds. AhR is a ligand-activated transcription factor necessary for the launch of transcriptional responses important in health and disease. In past decades, evidence has accumulated that AhR is associated with the cellular response to oxidative stress, and this property of AhR must be taken into account during investigations into a mechanism of action of xenobiotics that is able to activate AhR or that is susceptible to metabolic activation by enzymes encoded by the genes that are under the control of AhR. In this review, we examine various mechanisms by which AhR takes part in the oxidative-stress response, including antioxidant and prooxidant enzymes and cytochrome P450. We also show that AhR, as a participant in the redox balance and as a modulator of redox signals, is being increasingly studied as a target for a new class of therapeutic compounds and as an explanation for the pathogenesis of some disorders.

Unbalanced IDO1/IDO2 Endothelial Expression and Skewed Keynurenine Pathway in the Pathogenesis of COVID-19 and Post-COVID-19 Pneumonia

Despite intense investigation, the pathogenesis of COVID-19 and the newly defined long COVID-19 syndrome are not fully understood. Increasing evidence has been provided of metabolic alterations characterizing this group of disorders, with particular relevance of an activated tryptophan/kynurenine pathway as described in this review. Recent histological studies have documented that, in COVID-19 patients, indoleamine 2,3-dioxygenase (IDO) enzymes are differentially expressed in the pulmonary blood vessels, i.e., IDO1 prevails in early/mild pneumonia and in lung tissues from patients suffering from long COVID-19, whereas IDO2 is predominant in severe/fatal cases. We hypothesize that IDO1 is necessary for a correct control of the vascular tone of pulmonary vessels, and its deficiency in COVID-19 might be related to the syndrome’s evolution toward vascular dysfunction. The complexity of this scenario is discussed in light of possible therapeutic manipulations of the tryptophan/kynurenine pathway in COVID-19 and post-acute COVID-19 syndromes.

Importance of crosstalk between the microbiota and the neuroimmune system for tissue homeostasis

The principal function of inflammation is cellular defence against ‘danger signals’ such as tissue injury and pathogen infection to maintain the homeostasis of the organism. The initiation and progression of inflammation are not autonomous as there is substantial evidence that inflammation is known to be strongly influenced by ‘neuroimmune crosstalk’, involving the production and expression of soluble signalling molecules that interact with cell surface receptors. In addition, microbiota have been found to be involved in the development and function of the nervous and immune systems and play an important role in health and disease. Herein, we provide an outline of the mechanisms of neuroimmune communication in the regulation of inflammation and immune response and then provide evidence for the involvement of microbiota in the development and functions of the host nervous and immune systems. It appears that the nervous and immune systems in multicellular organisms have co‐evolved with the microbiota, such that all components are in communication to maximise the ability of the organism to adapt to a wide range of environmental stresses to maintain or restore tissue homeostasis.

Endoplasmic Reticulum Stress: A New Research Direction for Polycystic Ovary Syndrome?

Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrine disorders, with sporadic ovulation, excessive androgens, and polycystic ovarian changes as the main clinical manifestations. Due to the high heterogeneity of its clinical manifestations, the discussion on its pathogenesis has not been unified. Current research has found that genetic factors, hyperandrogenism, chronic inflammation and oxidative stress, insulin resistance, and obesity are strongly associated with PCOS. Recently, when studying the specific mechanisms of the abovementioned factors in PCOS, the biological response process of endoplasmic reticulum stress (ERS) has gradually come to researchers' attention, and several studies have confirmed the involvement of ERS in the pathogenesis of PCOS and the improvement of a series of pathological manifestations of PCOS after the application of ERS inhibitors, which may be a new entry point for the treatment of PCOS. In this article, we review the relationship between ERS and various pathogenic factors of PCOS.

Tryptophan Metabolites as Biomarkers for Esophageal Cancer Susceptibility, Metastasis, and Prognosis

BACKGROUND

Perturbation of tryptophan (TRP) metabolism contributes to the immune escape of cancer; however, the explored TRP metabolites are limited, and their efficacy in clarifying the susceptibility and progression of esophageal cancer (EC) remains ambiguous. Our study sought to evaluate the effects of the TRP metabolic profile on the clinical outcomes of EC using a Chinese population cohort; and to develop a risk prediction model targeting TRP metabolism.

METHOD

A total of 456 healthy individuals as control subjects and 393 patients with EC who were followed up for one year as case subjects were enrolled. Quantification of the plasma concentrations of TRP and its metabolites was performed using HPLC-MS/MS. The logistic regression model was applied to evaluate the effects of the clinical characteristics and plasma metabolites of the subjects on susceptibility and tumor metastasis events, whereas Cox regression analysis was performed to assess the overall survival (OS) of the patients.

RESULTS

Levels of creatinine and liver enzymes were substantially correlated with multiple metabolites/metabolite ratios in TRP metabolism, suggesting that hepatic and renal function would exert effects on TRP metabolism. Age- and sex-matched case-control subjects were selected using propensity score matching. Plasma exposure to 5-HT was found to be elevated 3.94-fold in case subjects (N = 166) compared to control subjects (N = 203), achieving an AUC of 0.811 for predicting susceptibility event. Subsequent correlation analysis indicated that a higher plasma exposure to 5-HIAA significantly increased the risk of lymph node metastasis (OR: 2.16, p = 0.0114). Furthermore, it was figured out that OS was significantly shorter for patients with elevated XA/KYN ratio (HR: 1.99, p = 0.0016), in which medium and high levels of XA/KYN versus low level had a significantly lower OS (HR: 0.48, p = 0.0080 and HR: 0.42, p = 0.0031, respectively).

CONCLUSION

This study provides a pivotal basis for targeting endogenous TRP metabolism as a potential therapeutic intervention.

Integrating Environment and Aging Research: Opportunities for Synergy and Acceleration

Despite significant overlaps in mission, the fields of environmental health sciences and aging biology are just beginning to intersect. It is increasingly clear that genetics alone does not predict an individual’s neurological aging and sensitivity to disease. Accordingly, aging neuroscience is a growing area of mutual interest within environmental health sciences. The impetus for this review came from a workshop hosted by the National Academies of Sciences, Engineering, and Medicine in June of 2020, which focused on integrating the science of aging and environmental health research. It is critical to bridge disciplines with multidisciplinary collaborations across toxicology, comparative biology, epidemiology to understand the impacts of environmental toxicant exposures and age-related outcomes. This scoping review aims to highlight overlaps and gaps in existing knowledge and identify essential research initiatives. It begins with an overview of aging biology and biomarkers, followed by examples of synergy with environmental health sciences. New areas for synergistic research and policy development are also discussed. Technological advances including next-generation sequencing and other-omics tools now offer new opportunities, including exposomic research, to integrate aging biomarkers into environmental health assessments and bridge disciplinary gaps. This is necessary to advance a more complete mechanistic understanding of how life-time exposures to toxicants and other physical and social stressors alter biological aging. New cumulative risk frameworks in environmental health sciences acknowledge that exposures and other external stressors can accumulate across the life course and the advancement of new biomarkers of exposure and response grounded in aging biology can support increased understanding of population vulnerability. Identifying the role of environmental stressors, broadly defined, on aging biology and neuroscience can similarly advance opportunities for intervention and translational research. Several areas of growing research interest include expanding exposomics and use of multi-omics, the microbiome as a mediator of environmental stressors, toxicant mixtures and neurobiology, and the role of structural and historical marginalization and racism in shaping persistent disparities in population aging and outcomes. Integrated foundational and translational aging biology research in environmental health sciences is needed to improve policy, reduce disparities, and enhance the quality of life for older individuals.

Aryl Hydrocarbon Receptor (AhR) Limits the Inflammatory Responses in Human Lung Adenocarcinoma A549 Cells via Interference with NF-κB Signaling

Apart from its role in the metabolism of carcinogens, the aryl hydrocarbon receptor (AhR) has been suggested to be involved in the control of inflammatory responses within the respiratory tract. However, the mechanisms responsible for this are only partially known. In this study, we used A549 cell line, as a human model of lung alveolar type II (ATII)-like cells, to study the functional role of the AhR in control of inflammatory responses. Using IL-1β as an inflammation inducer, we found that the induction of cyclooxygenase-2 and secretion of prostaglandins, as well as expression and release of pro-inflammatory cytokines, were significantly higher in the AhR-deficient A549 cells. This was linked with an increased nuclear factor-κB (NF-κB) activity, and significantly enhanced phosphorylation of its regulators, IKKα/β, and their target IκBα, in the AhR-deficient A549 cells. In line with this, when we mimicked the exposure to a complex mixture of airborne pollutants, using an organic extract of reference diesel exhaust particle mixture, an exacerbated inflammatory response was observed in the AhR-deficient cells, as compared with wild-type A549 cells. Together, the present results indicate that the AhR may act as a negative regulator of the inflammatory response in the A549 model, via a direct modulation of NF-κB signaling. Its role(s) in the control of inflammation within the lung alveoli exposed to airborne pollutants, especially those which simultaneously activate the AhR, thus deserve further attention.

Hypothesis: Emerging Roles for Aryl Hydrocarbon Receptor in Orchestrating CoV-2-Related Inflammation

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is the pathogenic agent of Coronavirus-Induced Disease-2019 (COVID-19), a multi-organ syndrome which primarily targets the respiratory system. In this review, considering the large amount of data pointing out the role of the Aryl hydrocarbon Receptor (AhR) in the inflammatory response and in the modulation of innate and adaptive immunity, we describe some mechanisms that strongly suggest its involvement in the management of COVID-19′s inflammatory framework. It regulates both the expression of Angiotensin Converting Enzyme-2 (ACE-2) and its stabilizing partner, the Broad neutral Amino acid Transporter 1 (B⁰AT1). It induces Indolamine 2,3 dioxygenase (IDO-1), the enzyme which, starting from Tryptophan (Trp), produces Kynurenine (Kyn, Beta-Anthraniloyl-L-Alanine). The accumulation of Kyn and the depletion of Trp arrest T cell growth and induce apoptosis, setting up an immune-tolerant condition, whereas AhR and interferon type I (IFN-I) build a mutual inhibitory loop that also involves NF-kB and limits the innate response. AhR/Kyn binding boosts the production of Interleukin-6 (IL-6), thus reinforcing the inflammatory state and counteracting the IDO-dependent immune tolerance in the later stage of COVID-19. Taken together, these data depict a framework where sufficient clues suggest the possible participation of AhR in the management of COVID-19 inflammation, thus indicating an additional therapeutic target for this disease.

Inhibition of aryl hydrocarbon receptor signaling promotes the terminal differentiation of human erythroblasts

The aryl hydrocarbon receptor (AHR) plays an important role during mammalian embryo development. Inhibition of AHR signaling promotes the development of hematopoietic stem/progenitor cells. AHR also regulates the functional maturation of blood cells, such as T cells and megakaryocytes. However, little is known about the role of AHR modulation during the development of erythroid cells. In this study, we used the AHR antagonist StemRegenin 1 (SR1) and the AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during different stages of human erythropoiesis to elucidate the function of AHR. We found that antagonizing AHR signaling improved the production of human embryonic stem cell (hESC)-derived erythrocytes and enhanced erythroid terminal differentiation. RNA-sequencing showed that SR1 treatment of proerythroblasts upregulated the expression of erythrocyte differentiation-related genes and downregulated actin organization-associated genes. We found that SR1 accelerated F-actin remodeling in terminally differentiated erythrocytes, favoring their maturation of the cytoskeleton and enucleation. We demonstrated that the effects of AHR inhibition on erythroid maturation were associated with F-actin remodeling. Our findings help uncover the mechanism for AHR-mediated human erythroid cell differentiation. We also provide a new approach toward the large-scale production of functionally mature human pluripotent stem cell-derived erythrocytes for use in translational applications.

Isolation of Transcriptomic-Quality Total RNA from Mouse Spinal Cords

Assessing cells, proteins, and total RNA in the spinal cord is vital for advancing our understanding of neuroinflammation and neurodegenerative diseases. For instance, immune cells infiltrate the spinal cord in the experimental autoimmune encephalomyelitis (EAE) model, commonly used to study multiple sclerosis. Thus, it is valuable to assess total RNA to determine the neuronal and inflammatory profiles in the spinal cord. Further, RNA profiles are useful for deciphering the effects of drugs or chemicals on neuroinflammation and neurodegenerative diseases such as EAE. The purpose of this protocol and the online video illustrating it is to describe and demonstrate the expulsion of the spinal cord from the mouse spinal column and homogenization of the spinal cord using liquid nitrogen for optimal RNA isolation. Although we present this method with spinal cords from EAE mice, the technique is broadly applicable, including RNA isolation from the spinal cords of healthy mice. Proper performance of these steps is critical to achieving a sufficient yield of transcriptomic-quality spinal cord RNA when combined with final isolation using commercially available kits. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Isolation of the spinal cord from the spinal column Support Protocol: Preparation of blunt-end needle for spinal cord isolation Basic Protocol 2: Spinal cord homogenization using liquid nitrogen Basic Protocol 3: Assessment of RNA purity, quantification, and integrity.

2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin potential impacts on peripheral blood mononuclear cells of endometriosis women

Endometriosis happens following the implantation of endometrial-derived tissues outside the uterine cavity. It has been suggested that 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD) is involved in endometriosis development. Furthermore, aryl hydrocarbon receptor (AHR), as a TCDD receptor, has been demonstrated to regulate immune responses. Nonetheless, data regarding the mechanisms, through which TCDD influences the immune system in endometriosis, are still inconclusive. Therefore, frequency of regulatory T cells (Tregs) and the expression of FOXP3, AHR and indoleamine 2, 3-dioxygenase 1 (IDO1) from endometriosis and non-endometriosis individuals were investigated in the absence and presence of TCDD; also, the concentration of IL-6 and kynurenine in the supernatant of cultures was assessed. The impact of TCDD-treated PBMCs on the migration capacity of menstrual blood-derived stromal stem cells (MenSCs) and monocyte chemoattractant protein-1 (MCP-1) and IL-6 production was determined. Here, we found that AHR and IDO1 expression levels were lower in endometriosis PBMCs; however, TCDD treatment increased AHR, FOXP3, IDO1, IL-6, and Treg levels in the endometriosis group (P ≤ 0.05-0.0001). TCDD-treated PBMCs increased the migration capacity of MenSCs and up-regulated MCP-1 and IL-6 levels in the PBMCs/MenSCs co-culture (P ≤ 0.01-0.0001). In conclusion, these results shed light on the probable mechanisms, through which AHR activation by chemical toxicants can impact inflammatory immune mediators involved in the development of endometriosis; also, these data support the idea that TCDD could promote endometriosis progression.

Polycyclic Aromatic Hydrocarbons from Fine Particulate Matter Induce Oxidative Stress and the Inflammatory Response in Human Vocal Fold Fibroblast Cells

Polycyclic aromatic hydrocarbons (PAHs) are toxicants in particulate matter (PM). The vocal fold, part of the larynx and a key structure for voicing, is always in contact with air. In recent epidemic studies, PM was shown to cause laryngitis; however, the basic mechanism has not been evaluated. In the present study, intracellular reactive oxygen species (ROS) and proinflammatory cytokine levels were analyzed after exposing human vocal fold fibroblasts (hVFFs) to PM standard reference material (SRM 2786). Expression levels of the aryl hydrocarbon receptor (AhR) and Cytochrome P450 Family 1 Subfamily A Member 1 (CYP1A1) were also evaluated. PM induced ROS formation and proinflammatory cytokines via the AhR CYP1A1 pathway and caused lipid peroxidation and DNA damage. Blocking AhR or CYP1A1 production using siRNAs significantly decreased ROS production and IL-6 and IL-9 expression in PM-exposed hVFFs, thus protecting the cells against oxidative stress. These results confirm that PAHs in PM play an important role in cell damage and inflammation, confirming a basic pathophysiologic relationship between PM exposure and laryngitis.

Aryl hydrocarbon receptor (Ahr)-dependent Il-22 expression by type 3 innate lymphoid cells control of acute joint inflammation

The aryl hydrocarbon receptor (AHR) controls several inflammatory and metabolic pathways involved in various diseases, including the development of arthritis. Here, we investigated the role of AHR activation in IL-22-dependent acute arthritis using the K/BxN serum transfer model. We observed an overall reduction of cytokine expression in Ahr-deficient mice, along with decreased signs of joint inflammation. Conversely, we report worsened arthritis symptoms in Il-22 deficient mice. Pharmacological stimulation of AHR with the agonist VAG539, as well as injection of recombinant IL-22, given prior arthritogenic triggering, attenuated inflammation and reduced joint destruction. The protective effect of VAG539 was abrogated in Il-22 deficient mice. Finally, conditional Ahr depletion of Rorc-expressing cells was sufficient to attenuate arthritis, thereby uncovering a previously unsuspected role of AHR in type 3 innate lymphoid cells during acute arthritis.

Induction of aryl hydrocarbon receptor in granulosa cells by endoplasmic reticulum stress contributes to pathology of polycystic ovary syndrome

Recent studies have uncovered the critical role of aryl hydrocarbon receptor (AHR) in various diseases, including obesity and cancer progression, independent of its previously identified role as a receptor for endocrine-disrupting chemicals (EDCs). We previously showed that endoplasmic reticulum (ER) stress, a newly recognized local factor in the follicular microenvironment, is activated in granulosa cells from patients with polycystic ovary syndrome (PCOS) and a mouse model of the disease. By affecting diverse functions of granulosa cells, ER stress contributes to PCOS pathology. We hypothesized that expression of AHR and activation of its downstream signaling were upregulated by ER stress in granulosa cells, irrespective of the presence of EDCs, thereby promoting PCOS pathogenesis. In this study, we found that AHR, AHR nuclear translocator (ARNT), and AHR target gene cytochrome P450 1B1 (CYP1B1) were upregulated in the granulosa cells of PCOS patients and model mice. We examined CYP1B1 as a representative AHR target gene. AHR and ARNT were upregulated by ER stress in human granulosa-lutein cells (GLCs), resulting in an increase in the expression and activity of CYP1B1. Administration of the AHR antagonist CH223191 to PCOS mice restored estrous cycling and decreased the number of atretic antral follicles, concomitant with downregulation of AHR and CYP1B1 in granulosa cells. Taken together, our findings indicate that AHR activated by ER stress in the follicular microenvironment contributes to PCOS pathology, and that AHR represents a novel therapeutic target for PCOS.

Lack of association between multiple polymorphisms in aryl hydrocarbon receptor (AhR) gene and cancer susceptibility

BACKGROUND

The aryl hydrocarbon receptor (AhR) is commonly known as an environmental sensor. Polymorphisms in AhR gene have been implicated in susceptibility to cancer. However, the results were controversial. This study was conducted to quantitatively summarize the association between AhR polymorphisms and cancer risk by meta-analysis.

METHODS

Relevant reports were searched in four databases (Embase, PubMed, Wanfang, and China National Knowledge Infrastructure). We used pooled odds ratio (OR) and 95% confidence interval (95% CI) to evaluate the strength of the association in both standard and cumulative meta-analysis. Subgroup and sensitivity analysis was also performed, and between-study heterogeneity and publication bias were checked.

RESULTS

A total of seventeen studies referring to three AhR polymorphisms (rs2066853, rs7796976, and rs2074113) were identified, and 9557 cases and 10038 controls were included. There was no statistically significant association of AhR rs2066853 polymorphism with cancer risk in the overall population, and the negative results were repeated in subgroup analysis by the ethnicity and cancer type. Concerning AhR rs7796976 or rs2074113 polymorphism, no significant correlation was detected. Moreover, these non-significant findings were stable in sensitivity analysis, and the cumulative meta-analysis indicated a trend of no significant link between this three AhR polymorphisms and cancer risk as more data accumulated over time.

CONCLUSION

This meta-analysis provides evidence that the rs2066853, rs7796976, or rs2074113 polymorphism in AhR gene is not a susceptible predictor of cancer. Further clinical and functional investigation between AhR polymorphisms and cancer susceptibility are needed.

Aryl Hydrocarbon Receptor Connects Inflammation to Breast Cancer

Aryl hydrocarbon receptor (AhR), an evolutionary conserved transcription factor, is a pleiotropic signal transductor. Thanks to its promiscuous ligand binding domain, during the evolution of eukaryotic cells its developmental functions were integrated with biosensor functions. Its activation by a multitude of endogenous and exogenous molecules stimulates its participation in several pathways, some of which are linked to inflammation and breast cancer (BC). Over time, the study of this malignancy has led to the identification of several therapeutic targets in cancer cells. An intense area of study is dedicated to BC phenotypes lacking adequate targets. In this context, due to its high constitutive activation in BC, AhR is currently gaining more and more attention. In this review, I have considered its interactions with: 1. the immune system, whose dysregulation is a renowned cancer hallmark; 2. interleukin 6 (IL6) which is a pivotal inflammatory marker and is closely correlated to breast cancer risk; 3. NF-kB, another evolutionary conserved transcription factor, which plays a key role in immunoregulatory functions, inflammatory response and breast carcinogenesis; 4. kynurenine, a tryptophan-derived ligand that activates and bridges AhR to chronic inflammation and breast carcinogenesis. Overall, the data here presented form an interesting framework where AhR is an interesting connector between inflammation and BC.