Tetrabromoethylcyclohexane (TBECH) exhibits immunotoxicity in murine macrophages

Notoginsenoside R1 ameliorates the inflammation induced by amyloid‑β by suppressing SphK1‑mediated NF‑κB activation in PC12 cells

Alzheimer's disease (AD) is the most common type of age‑related dementia, and causes progressive memory degradation, neuronal loss and brain atrophy. The pathological hallmarks of AD consist of amyloid‑β (Aβ) plaque accumulation and abnormal neurofibrillary tangles. Amyloid fibrils are constructed from Aβ peptides, which are recognized to assemble into toxic oligomers and exert cytotoxicity. The fibrillar Aβ‑protein fragment 25‑35 (Aβ25‑35) induces local inflammation, thereby exacerbating neuronal apoptosis. Notoginsenoside R1 (NGR1), one of the primary bioactive ingredients isolated from Panax notoginseng, exhibits effective anti‑inflammatory and anti‑oxidative activities. However, NGR1 pharmacotherapies targeting Aβ‑induced inflammation and cell injury cascade remain to be elucidated. The present study investigated the effect and mechanism of NGR1 in Aβ25‑35‑treated PC12 cells. NGR1 doses between 250 and 1,000 µg/ml significantly increased cell viability suppressed by 20 µM Aβ25‑35 peptide treatment. Notably, the present study demonstrated that Aβ25‑35 peptide‑induced sphingosine kinase 1 (SphK1) signaling activation was reduced after NGR1 treatment, further inhibiting the downstream NF‑κB inflammatory signaling pathway. In addition, administration of SphK1 inhibitor II (SKI‑II), a SphK1 inhibitor, also significantly reduced Aβ25‑35 peptide‑induced apoptosis and the ratio of NF‑κB p‑p65/p65. Furthermore, SphK1 knockdown in PC12 cells using small interfering RNA alleviated Aβ‑induced cell apoptosis and inflammation, suggesting a pivotal role of SphK1 signaling in the anti‑inflammatory effect of NGR1. In summary, NGR1 alleviated inflammation and apoptosis stimulated by Aβ25‑35 by inhibiting the SphK1/NF‑κB signaling pathway and may be a promising agent for future AD treatment.

Cellular and physiological mechanisms of halogenated and organophosphorus flame retardant toxicity

Flame retardants (FRs) are chemical substances used to inhibit the spread of fire in numerous industrial applications, and their abundance in modern manufactured products in the indoor and outdoor environment leads to extensive direct and food chain exposure of humans. Although once considered relatively non-toxic, FRs are demonstrated by recent literature to have disruptive effects on many biological processes, including signaling pathways, genome stability, reproduction, and immune system function. This review provides a summary of research investigating the impact of major groups of FRs, including halogenated and organophosphorus FRs, on animals and humans in vitro and/or in vivo. We put in focus those studies that explained or referenced the modes of FR action at the level of cells, tissues and organs. Since FRs are highly hydrophobic chemicals, their biophysical and biochemical modes of action usually involve lipophilic interactions, e.g. with biological membranes or elements of signaling pathways. We present selected toxicological information about these molecular actions to show how they can lead to damaging membrane integrity, damaging DNA and compromising its repair, changing gene expression, and cell cycle as well as accelerating cell death. Moreover, we indicate how this translates to deleterious bioactivity of FRs at the physiological level, with disruption of hormonal action, dysregulation of metabolism, adverse effects on male and female reproduction as well as alteration of normal pattern of immunity. Concentrating on these subjects, we make clear both the advances in knowledge in recent years and the remaining gaps in our understanding, especially at the mechanistic level.

Research advances in identification procedures of endocrine disrupting chemicals

Endocrine disrupting chemicals (EDCs) are increasingly concerned substance endangering human health and environment. However, there is no unified standard for identifying chemicals as EDCs, which is also controversial internationally. In this review, the procedures for EDC identification in different organizations/countries were described. Importantly, three aspects to be considered in identifying chemical substances as EDCs were summarized, which were mechanistic data, animal experiments, and epidemiological information. The relationships between them were also discussed. To elaborate more clearly on these three aspects of evidence, scientific data on some chemicals including bisphenol A, 1,2-dibromo-4-(1,2 dibromoethyl) cyclohexane and perchlorate were collected and evaluated. Altogether, the above three chemicals were assessed for interfering with hormones and elaborated their health hazards from macroscopic to microscopic. This review is helpful for standardizing the identification procedure of EDCs.

Developmental immunotoxicity of maternal exposure to yttrium nitrate on BALB/c offspring mice

Yttrium is a typical heavy rare earth element with widespread use in numerous sectors. Only one previous study has indicated that yttrium has the potential to cause developmental immunotoxicity (DIT). Therefore, there remains a paucity of evidence on the DIT of yttrium. This study aimed to explore the DIT of yttrium nitrate (YN) and the self-recovery of YN-induced DIT. Dams were treated with 0, 0.2, 2, and 20 mg/kg bw/day YN by gavage during gestation and lactation. No significant changes were found in innate immunity between the control and YN-treated groups in offspring. In female offspring at postnatal day 21 (PND21), YN markedly inhibited humoral and cellular immune responses, the proliferative capacity of splenic T lymphocytes, and the expression of costimulatory molecules in splenic lymphocytes. Moreover, the inhibitory effect on cellular immunity in female offspring persisted to PND42. Unlike females, YN exposure did not change the adaptive immune responses in male offspring. Overall, maternal exposure to YN showed a strong DIT to offspring, with the lowest effective dose of 0.2 mg/kg in the current study. The toxicity of cellular immunity could persist throughout development into adulthood. There were sex-specific differences in YN-induced DIT, with females being more vulnerable.

Valorization and characterization of bio-oil from Salvadora persica seed for air pollutant adsorption

Salvadora persica (SP) is an important medicinal plant. Numerous articles have been conducted on the leaf, the roots, and the stem of the plant, but there is little information about the seed. Thus, the present work tries to identify the chemical composition of SP seed bio-oil and investigates its use as an adsorbent for cyclohexane removal. This study extracted bio-oil from seeds using different polar and non-polar organic solvents. Two techniques have been used to determine the chemical composition of the bio-oil extracted: FTIR and GC-MS. Results show that the extracted bio-oil presented 13 new major organic bio-compounds in n-hexane and ethanol SP seed extracts. Moreover, the analytical results showed that the two extracts are complex and contained thiocyanic acid, benzene, 3-pyridine carboxaldehyde, benzyl nitrile, ethyl tridecanoate, ethyl oleate, and dodecanoic acid ethyl ester. Additionally, each technique of analysis showed that the extracted bio-oils from SP seeds are rich in non-polar compounds. Indeed, the major fatty acids obtained are pentadecylic acid, myristic acid, lauric acid, oleic acid, margaric acid, and tricosanoic acid. This work provides guidelines for identifying these compounds, among others, and offers a platform for using SP seeds as a herbal alternative for various chemical, industrial, and medical applications. Furthermore, the capacity of SP extracts for air pollution treatment, namely, the removal of cyclohexane in batch mode, was investigated. Results showed that cyclohexane adsorption could be a chemical process involving both monolayer and multilayer adsorption mechanisms. The pores and the grooves on the surface of the SP bio-oil extract helped in adsorbing the cyclohexane with an outstanding maximum removal capacity of about 674.23 mg/g and 735.75 mg/g, respectively, for the ethanol and hexane SP extracts, which is superior to many other recent adsorbents.

Triphenyl phosphate-induced macrophages dysfunction by activation TLR4-mediated ERK/NF-κB pathway

Triphenyl phosphate (TPHP) is one of the most widely used organic phosphorus flame retardants and is ubiquitous in the environment. Studies have been reported that TPHP may lead to obesity, neurotoxicity and reproductive toxicity, but its impact on the immune system is almost blank. The present study was aimed to investigate the potential immunotoxicity of TPHP on macrophages and its underlying mechanism. The results demonstrated for the first time that TPHP (12.5, 25, and 50 μM)-induced F4/80⁺ CD11c⁺ phenotype of RAW 264.7 macrophages, accompanied by increased mRNA levels of inflammatory mediators, antigen-presenting genes (Cd80, Cd86, and H2-Aa), and significantly enhanced the phagocytosis of macrophage. Meanwhile, TPHP increased the expression of Toll-like receptor 4 (TLR4), and its co-receptor CD14, leading to significant activation of the downstream ERK/NF-κB pathway. However, co-exposure of cells to TAK-242, a TLR4 inhibitor, suppressed TPHP-induced F4/80⁺ CD11c⁺ phenotype, and down-regulated inflammatory mediators and antigen-presentation related genes, via blocked the TLR4/ERK/NF-κB pathway. Taken together, our results suggested that TPHP could induce macrophage dysfunction through activating TLR4-mediated ERK/NF-κB signaling pathway, and it may be the potential reason for health-threatening consequences.

The potential immunotoxicity of emamectin benzoate on the human THP-1 macrophages

Emamectin benzoate (EMB) as one of the typical biological pesticides has a wide range of applications in agriculture. However, the immune toxic effects of EMB in human received limited attention. In our study, THP-1 macrophage as an in vitro model was used to evaluate immune functions exposed to EMB. We observed that EMB inhibited phagocytic activity and respiratory burst capacity of macrophages without inducing cellular toxicity, implying the potential immunosuppression. Besides, EMB disturbed the cytokines balance embodied in the increase of TNF-α, IL-1β, IL-6, CCL27, CXCL8 mRNA expression and the decrease of IL-4, IL-13, IL-10 mRNA expression. EMB could exhibit pro-inflammatory responses in macrophages and promote the conversion of macrophages to M1 phenotype. Moreover, NF-κB pathway involved in regulating immune function from KEGG pathway analysis. EMB exposure could activate the NF-κB pathway in THP-1 macrophages by exploring the critical proteins. This research provided insights on immunotoxicity evaluation and clarified EMB-induced immunotoxicity was related to NF-κB pathway activation.

Platycodin D-Induced Immunotoxicity in RAW 264.7 Macrophages via Oxidative Stress-Mediated Apoptosis

Platycodin D (PD) is a naturally occurring, biologically active triterpenoid saponin isolated from a medicinal food homology plant called Platycodon grandiflorus (Jacq.) A. DC. It is involved in the processing of various biological activities. While investigating the anti-inflammatory property of PD using lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophage cells, we unexpectedly found that PD exhibited toxicity to RAW 264.7 cells. In this study, the toxic effect of PD on RAW 264.7 cells was systematically evaluated for the first time. The results showed that PD (12.5−200 µM) significantly reduced cell viability and inhibited cell proliferation in a dose-dependent manner. At a concentration of 20 µM, PD significantly increased lactate dehydrogenase activity and the mRNA and protein expression of Bax, p53, Casp3, IL-1β, and TNF-α. Interestingly, PD (0.8−20 µM) inhibited the expression of inflammatory cytokines in LPS-stimulated RAW 264.7 cells. PD (20 µM) also significantly increased reactive oxygen species (ROS) levels and the expression of oxidative stress-related genes and proteins. This study revealed that PD exhibited immunotoxicity to RAW 264.7 cells, with possible mechanisms including oxidative stress-mediated apoptosis resulting in activation of the mitochondrial apoptosis pathway and dysregulated expression of inflammatory cytokines. This study evaluated the impact of PD on immunity and provided guidelines for its future biological application.

HBCD, TBECH, and BTBPE exhibit cytotoxic effects in human vascular endothelial cells by regulating mitochondria function and ROS production

Brominated flame retardants (BFRs), such as, 1,2,5,6-tetrabromocyclooctane (HBCD), 1,2-dibromo-4-(1,2-dibromopropyl)cyclohexane (TBECH), and 1 1,2-bis-(2,4,6-tribromophenoxy)ethane (BTBPE), have garnered increasing attention due to their potent biological effects. In the present study, the toxicity of HBCD, TBECH, and BTBPE in human vascular endothelial cells (ECs) was explored. The data showed that HBCD, TBECH, and BTBPE induced cytotoxicity, namely dose-dependent cell viability reduction, cell membrane permeability and apoptosis increase, migration, and lumen formation inhibition. Moreover, HBCD was found to be more toxic than BTBPE or TBECH. Exposure to HBCD, TBECH, and BTBPE led to the production of reactive oxygen species, mitochondrial superoxide generation, and mitochondrial membrane potential collapse, implying that reactive stress caused the cytotoxicity. The ATP content, glutathione content, superoxide dismutase, and MDA activities were reduced, indicating that mitochondrial dysfunction may be the key mechanisms responsible for apoptosis. The present study suggested that mitochondria are a new target of BFRs in ECs and further deepened our understanding of the developmental toxicity of BFRs.

Flame Retardants-Mediated Interferon Signaling in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a growing concern worldwide, affecting 25% of the global population. NAFLD is a multifactorial disease with a broad spectrum of pathology includes steatosis, which gradually progresses to a more severe condition such as nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and eventually leads to hepatic cancer. Several risk factors, including exposure to environmental toxicants, are involved in the development and progression of NAFLD. Environmental factors may promote the development and progression of NAFLD by various biological alterations, including mitochondrial dysfunction, reactive oxygen species production, nuclear receptors dysregulation, and interference in inflammatory and immune-mediated signaling. Moreover, environmental contaminants can influence immune responses by impairing the immune system’s components and, ultimately, disease susceptibility. Flame retardants (FRs) are anthropogenic chemicals or mixtures that are being used to inhibit or delay the spread of fire. FRs have been employed in several household and outdoor products; therefore, human exposure is unavoidable. In this review, we summarized the potential mechanisms of FRs-associated immune and inflammatory signaling and their possible contribution to the development and progression of NAFLD, with an emphasis on FRs-mediated interferon signaling. Knowledge gaps are identified, and emerging pharmacotherapeutic molecules targeting the immune and inflammatory signaling for NAFLD are also discussed.

A review of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane in the environment and assessment of its persistence, bioaccumulation and toxicity

Following the ban of many historically-used flame retardants (FRs), numerous replacement chemicals have been produced and used in products, with some being identified as environmental contaminants. One of these replacement flame retardants is 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (DBE-DBCH; formerly abbreviated as TBECH), which to date has not been identified for risk assessment and potential regulation. DBE-DBCH technical mixtures consist largely of α- and β-diastereomers with trace amounts of γ- and δ-DBE-DBCH. The α- and β-isomers are known contaminants in various environmental media. While current global use and production volumes of DBE-DBCH are unknown, recent studies identified that DBE-DBCH concentrations were among the highest of the measured bromine-based FRs in indoor and urban air in Europe. Yet our mass balance fugacity model and modeling of the physical-chemical properties of DBE-DBCH estimated only 1% partitioning to air with a half-life of 2.2 d atmospherically. In contrast, our modeling characterized DBE-DBCH adsorbing strongly to suspended particulates in the water column (~12%), settling onto sediment (2.5%) with minimal volatilization, but with most partitioning and adsorbing strongly to soil (~85%) with negligible volatilization and slow biodegradation. Our modeling further predicted that organisms would be exposed to DBE-DBCH through partitioning from the dissolved aquatic phase, soil, and by diet, and given its estimated logKow (5.24) and a half-life of 1.7 d in fish, DBE-DBCH is expected to bioaccumulate into lipophilic tissues. Low concentrations of DBE-DBCH are commonly measured in biota and humans, possibly because evidence suggests rapid metabolism. Yet toxicological effects are evident at low exposure concentrations: DBE-DBCH is a proven endocrine disruptor of sex and thyroid hormone pathways, with in vivo toxic effects on reproductive, metabolic, and other endpoints. The objectives of this review are to identify the current state of knowledge concerning DBE-DBCH through an evaluation of its persistence, potential for bioaccumulation, and characterization of its toxicity, while identifying areas for future research.

Preventive and Therapeutic Spermidine Treatment Attenuates Acute Colitis in Mice

Inflammatory bowel disease (IBD) is associated with acute and chronic inflammation of the gastrointestinal tract and has emerged to be a global disease. Spermidine, a natural polyamine, plays a critical role in maintaining cellular homeostasis. Herein, we investigated the impact and mechanism of spermidine on both dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzenesulfonic acid solution (TNBS)-induced colitis in mice. We found that spermidine exerted protective effects against acute colitis, evidenced by reduced disease activity index (DAI) and colonic inflammation, increased colonic length, and upregulated tight junction proteins in these two colitis models. Importantly, spermidine exerted significant therapeutic and preventive effects against DSS-induced colitis. Pre- and post-treatment with spermidine reduced the expression of proinflammatory cytokines, phosphorylation of (nuclear factor-κB) NF-κB and (mitogen-activated protein kinase) MAPK, and the activation of F4/80 macrophages and T cells in the colon. Furthermore, spermidine upregulated M2 macrophage markers, whereas it downregulated M1 markers in the inflamed colons. In parallel, spermidine reduced M1 pro-inflammatory markers and enhanced M2 anti-inflammatory genes in RAW264.7 cells. These results revealed that spermidine-ameliorated colitis might be through the regulation of M1/M2 macrophage polarization. In addition, spermidine treatment also alleviated LPS/TNF-α-induced inflammation in Caco-2 cells. Taken together, spermidine prevented and reversed colonic inflammation in colitis mice and might be a promising candidate for IBD intervention.