The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor thought to mediate a number of physiological roles in the body, is becoming a target of interest for the development of new therapeutics. However, previous research has demonstrated that the downstream effects of AhR ligands cannot be predicted based simply on whether a ligand acts as an agonist or antagonist and the persistence of AhR signaling is thought to be a key determining feature. The current study investigated the AhR activity of four halogenated indoles isolated from the New Zealand red alga, Rhodophyllis membranacea: 4,7-dibromo-2,3-dichloroindole (4DBDCI), 7-bromo-2,3-dichloro-6-iodoindole (BDCII), 6,7-dibromo-2,3-dichloroindole (6DBDCI) and 2,6,7-tribromo-3-chloroindole (TBCI). Their ability to activate AhR signaling, measured as CYP1A1 activity via the ethoxyresorufin O-deethylase (EROD) assay, was determined in human HepG2, mouse Hepa1c1c7 and rat H4IIE liver cancer cells. All four compounds induced CYP1A1 activity in HepG2 cells, suggesting they all acted as AhR agonizts. 4DBDCI was particularly efficacious, inducing an 11-fold increase. Hepa1c1c7 and H4IIE cells, however, were generally less responsive to the halogenated indoles. All four compounds were persistent AhR agonizts, inducing peak CYP1A1 activity after 72 h. Moreover, the 2,3,6,7-substituted BDCII, 6DBDCI and TBCI, but not 4DBDCI, competed with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for AhR binding as observed by the inhibition of TCDD-induced CYP1A1 activity. Overall, the current study has characterized four previously untested AhR ligands, highlighting differences in species sensitivity and persistence of signaling to provide a framework for their potential future use.

Indigo naturalis, a herbal medicine purified from indigo-containing plants, such as Strobilanthes cusia, Isatis tinctoria, and Polygonum tinctorium, has been reported to be useful in the treatment of ulcerative colitis by activating the aryl hydrocarbon receptor. However, the aryl hydrocarbon receptor pathway causes crucial side effects, such as pulmonary arterial hypertension. Although P. tinctorium is one of the plant derivatives of indigo naturalis, it is not identical to it. To date, the pure leaves of P. tinctorium have not been reported to ameliorate ulcerative colitis. Therefore, we investigated the effect of pure P. tinctorium leaves, which are consumed in some regions, on experimental colitis induced in mice using sodium dextran sulfate. We found that P. tinctorium leaves ameliorated weight loss (P < 0.01) and pathological inflammatory changes in the colon (P < 0.05), enhanced mRNA expression of interleukin-10 (P < 0.05), and decreased expression of tumor necrosis factor-in colonic tissues (P < 0.05), as determined using quantitative real-time reverse transcription polymerase chain reaction. The intraperitoneal administration of an aryl hydrocarbon receptor antagonist did not antagonize the inhibition of mucosal destruction, whereas an anti-interleukin-10 receptor antibody did. These results suggest that P. tinctorium ameliorate sodium dextran sulfate-induced intestinal inflammation via interleukin-10-related pathway, independent of the aryl hydrocarbon receptor pathway. P. tinctorium leaves have the potential to be a new, safe treatment for ulcerative colitis.

Tumor cells have unique metabolic programming that is biologically distinct from that of corresponding normal cells. Resetting tumor metabolic programming is a promising strategy to ameliorate drug resistance and improve the tumor microenvironment. Here, we show that carboxyamidotriazole (CAI), an anticancer drug, can function as a metabolic modulator that decreases glucose and lipid metabolism and increases the dependency of colon cancer cells on glutamine metabolism. CAI suppressed glucose and lipid metabolism utilization, causing inhibition of mitochondrial respiratory chain complex I, thus producing reactive oxygen species (ROS). In parallel, activation of the aryl hydrocarbon receptor (AhR) increased glutamine uptake via the transporter SLC1A5, which could activate the ROS-scavenging enzyme glutathione peroxidase. As a result, combined use of inhibitors of GLS/GDH1, CAI could effectively restrict colorectal cancer (CRC) energy metabolism. These data illuminate a new antitumor mechanism of CAI, suggesting a new strategy for CRC metabolic reprogramming treatment.

Dioxin-like molecules have been associated with endocrine disruption and liver disease. To better understand aryl hydrocarbon receptor (AHR) biology, metabolic phenotyping and liver proteomics were performed in mice following ligand-activation or whole-body genetic ablation of this receptor. Male wild type (WT) and Ahr -/- mice (Taconic) were fed a control diet and exposed to 3,3\',4,4\',5-pentachlorobiphenyl (PCB126) (61 nmol/kg by gavage) or vehicle for two weeks. PCB126 increased expression of canonical AHR targets (Cyp1a1 and Cyp1a2) in WT but not Ahr -/-. Knockouts had increased adiposity with decreased glucose tolerance; smaller livers with increased steatosis and perilipin-2; and paradoxically decreased blood lipids. PCB126 was associated with increased hepatic triglycerides in Ahr -/-. The liver proteome was impacted more so by Ahr -/- genotype than ligand-activation, but top gene ontology (GO) processes were similar. The PCB126-associated liver proteome was Ahr-dependent. Ahr principally regulated liver metabolism (e.g., lipids, xenobiotics, organic acids) and bioenergetics, but it also impacted liver endocrine response (e.g., the insulin receptor) and function, including the production of steroids, hepatokines, and pheromone binding proteins. These effects could have been indirectly mediated by interacting transcription factors or microRNAs. The biologic roles of the AHR and its ligands warrant more research in liver metabolic health and disease.

Dioxins are persistent environmental toxins that are still present in the food supply despite strong efforts to minimize exposure. Dioxins ingested by humans accumulate in fat and are excreted very slowly, so their long-term effects at low concentrations are a matter of concern. It is necessary to consider long-term, low-dose continuous administration under conditions that are as close as possible to a person\'s diet. In this study, we orally administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most common dioxin, at low doses in mice and observed the immunological effects. We found that antigen-specific (OVA) antibody production in the serum increased dose-dependently by TCDD concentrations below 500 ng/kg after long-term (10 weeks) exposure. Similar increases were seen in fecal and vaginal samples but were not significant. Th1 and Th2 lymphocyte responses, as determined by antibody and cytokine production, also significantly increased dose-dependently up to 500 ng/kg TCDD, and the Th1/Th2 balance was shifted toward Th1. These results indicate that low-dose, long-term TCDD exposure results in immunological abnormalities, perhaps by increasing antigen permeability. Different doses of dioxins may have opposing effects, being immunostimulatory at low doses (100 ng/kg/day) and immunosuppressive at high doses (500 ng/kg/day).

Immune checkpoint blockade has been proven to have great therapeutic potential and has revolutionized the treatment of tumors. However, various limitations remain, including the low response rate of exhausted T cells and mutual regulation of multiple immunosuppressive cell types that compromise the effect of single-target therapy. Nano-delivery systems can be used to regulate the tumor immune microenvironment in favor of immunotherapy. In this study, we constructed a polypeptide-based micellar system that encapsulates an aryl hydrocarbon receptor (AhR) inhibitor (CH223191) conjugated to T cell activator anti-CD28. The inhibition of AhR activation downregulates the fraction of immunosuppressive cells and effectively inhibits tumor cell metastasis. In addition, the combination with co-stimulatory antibodies improves T-cell activation and synergistically enhances the antitumor effect of AhR inhibitors. The micellar system developed in this study represents a novel and effective tumor immunotherapy approach.

UNASSIGNED: Coronavirus disease 2019 is characterized by the elevation of a broad spectrum of inflammatory mediators associated with poor disease outcomes. We aimed at an in-silico analysis of regulatory microRNA and their transcription factors (TF) for these inflammatory genes that may help to devise potential therapeutic strategies in the future.
UNASSIGNED: The cytokine regulating immune-expressed genes (CRIEG) were sorted from literature and the GEO microarray dataset. Their co-differentially expressed miRNA and transcription factors were predicted from publicly available databases. Enrichment analysis was done through mienturnet, MiEAA, Gene Ontology, and pathways predicted by KEGG and Reactome pathways. Finally, the functional and regulatory features were analyzed and visualized through Cytoscape.
UNASSIGNED: Sixteen CRIEG were observed to have a significant protein-protein interaction network. The ontological analysis revealed significantly enriched pathways for biological processes, molecular functions, and cellular components. The search performed in the miRNA database yielded ten miRNAs that are significantly involved in regulating these genes and their transcription factors.
UNASSIGNED: An in-silico representation of a network involving miRNAs, CRIEGs, and TF, which take part in the inflammatory response in COVID-19, has been elucidated. Thus, these regulatory factors may have potentially critical roles in the inflammatory response in COVID-19 and may be explored further to develop targeted therapeutic strategies and mechanistic validation.

Rutaecarpine is reported as a potent inducer of CYP1A2 enzyme in rats. There are natural herbal supplements containing rutaecarpine that are designed to enhance the CYP1A2-dependent removal of caffeine from blood so that people can have coffee later in the day without causing sleep interference. This study aimed to determine the minimum amount of time needed from oral rutaecarpine administration until the observed effect of rutaecarpine on caffeine pharmacokinetics (PK) in 15 male Sprague-Dawley rats. PK parameters for caffeine and its metabolites in the control and rutaecarpine groups were calculated using WinNonlin®. Results showed that orally administered rutaecarpine at 100 mg/kg dose as early as 3 h before oral caffeine administration significantly decreased the oral systemic exposure and mean residence time of caffeine and its metabolites due to decreased caffeine bioavailability (by up to 75%) and increased clearance. The systemic exposure of caffeine and its metabolites were also decreased when caffeine was given intravenously, though this effect was less pronounced than when caffeine was given orally. Although plasma level of rutaecarpine was undetectable (less than 10 ng/mL), rutaecarpine still induced hepatic CYP1A2 activity. Results from 7-methoxyresorufin O-demethylation activity, which is specific to CYP1A2, showed that 3 h after one rutaecarpine oral dose, CYP1A2 activity in rat liver tissue was increased by 3- fold. This finding suggested that rutaecarpine effectively induced CYP1A2 activity in the liver.

Environmental hexachlorobenzene (HCB) increases blood pressure (BP) in female rats, causing alterations in arterial structure and function. Here we study the role of Angiotensin II receptor type 1 (AT1) in HCB-induced hypertension through the use of AT1 antagonist losartan. HCB-treated male rats showed a 22.7% increase in BP which was prevented by losartan. Losartan blocked HCB-induced changes in arterial morphology (decreased aorta cell number and increased wall thickness). Losartan also prevented HCB-induced alterations in artery relaxation by acetylcholine and nitroprusside but not the reduction in the maximum contraction by phenylephrine. Losartan rescued arterial molecular alterations caused by HCB (i.e. an increase in TGF-β1 and AT1 expression and a decrease in eNOS expression and nitrite levels) and reduced hydrogen sulfide plasma concentration. In conclusion: in this work we demonstrate that AT1 activity is involved in HCB effects on the vascular system leading to hypertension.

A growing number of public health bodies, regulators and governments around the world consider electronic vapor products a lower risk alternative to conventional cigarettes. Of critical importance are rapid new approach methodologies to enable the screening of next generation products (NGPs) also known as next generation tobacco and nicotine products. In this study, the activity of conventional cigarette (3R4F) smoke and a range of NGP aerosols (heated tobacco product, hybrid product and electronic vapor product) captured in phosphate buffered saline, were screened by exposing a panel of human cell-based model systems using Biologically Multiplexed Activity Profiling (BioMAP® Diversity PLUS® Panel, Eurofins Discovery). Following exposure, the biological activity for a wide range of biomarkers in the BioMAP panel were compared to determine the presence of toxicity signatures that are associated with specific clinical findings. NGP aerosols were found to be weakly active in the BioMAP Diversity PLUS Panel (≤3/148 biomarkers) whereas significant activity was observed for 3R4F (22/148 biomarkers). Toxicity associated biomarker signatures for 3R4F included immunosuppression, skin irritation and thrombosis, with no toxicity signatures seen for the NGPs. BioMAP profiling could effectively be used to differentiate between complex mixtures of cigarette smoke or NGP aerosol extracts in a panel of human primary cell-based assays. Clinical validation of these results will be critical for confirming the utility of BioMAP for screening NGPs for potential adverse human effects.