Arsenic affects inflammatory cytokine expression in Gallus gallus brain tissues

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

Recapitulation of Structure-Function-Regulation of Blood-Brain Barrier under (Patho)Physiological Conditions

The blood-brain barrier (BBB) is a remarkable and intricate barrier that controls the exchange of molecules between the bloodstream and the brain. Its role in maintaining the stability of the central nervous system cannot be overstated. Over the years, advancements in neuroscience and technology have enabled us to delve into the cellular and molecular components of the BBB, as well as its regulation. Yet, there is a scarcity of comprehensive reviews that follow a logical framework of structure-function-regulation, particularly focusing on the nuances of BBB regulation under both normal and pathological conditions. This review sets out to address this gap by taking a historical perspective on the discovery of the BBB and highlighting the major observations that led to its recognition as a distinct brain barrier. It explores the intricate cellular elements contributing to the formation of the BBB, including endothelial cells, pericytes, astrocytes, and neurons, emphasizing their collective role in upholding the integrity and functionality of the BBB. Furthermore, the review delves into the dynamic regulation of the BBB in physiological states, encompassing neural, humoral, and auto-regulatory mechanisms. By shedding light on these regulatory processes, a deeper understanding of the BBB's response to various physiological cues emerges. This review also investigates the disruption of the BBB integrity under diverse pathological conditions, such as ischemia, infection, and toxin exposure. It elucidates the underlying mechanisms that contribute to BBB dysfunction and explores potential therapeutic strategies that aim to restore the BBB integrity and function. Overall, this recapitulation provides valuable insights into the structure, functions, and regulation of the BBB. By integrating historical perspectives, cellular elements, regulatory mechanisms, and pathological implications, this review contributes to a more comprehensive understanding of the BBB and paves the way for future research and therapeutic interventions.

Arsenic induced neurotoxicity in the brain of ducks: The potential involvement of the gut-brain axis

BACKGROUND

Arsenic is a widely distributed ecotoxic pollutant that has been found to cause neurotoxicity in a variety of species. Gut-brain axis is a two-way information network between the gut microbiome and the brain, which is closely related to organismal health. However, the role of the gut-brain axis in arsenic-induced neurotoxicity remains largely unknown.

METHODS

In order to explore whether there is a relationship between brain and gut microbiota of meat ducks, we performed molecular biological detection including RT-qPCR and Western blot, as well as morphological detection including, HE staining and immunohistochemistry. Meanwhile, intestinal contents were analyzed using 16 S ribosomal RNA gene sequencing and analysis RESULTS: In this study, we investigated whether arsenic trioxide (ATO) can activate the gut microbiome-brain axis to induce intestinal and brain injury. The results showed that ATO-exposure disrupted the diversity balance of intestinal microbiota and integrity and injured the intestinal structure. ATO-exposure also reduced the number of glycogen and goblet cells in the duodenum. In addition, exposure to ATO caused intestinal inflammatory injury by activating NF-κB signaling pathway and promoting the expression of its target genes. Meanwhile, the tight junction-related proteins (ZO-1, occludin) of gut and brain were reduced by ATO exposure. Furthermore, results also revealed that ATO-exposure induced brain injury, including neuronal cell vacuolization and reduced numbers of neuronal cells in the cortex and hippocampus. Remarkably, ATO-exposure also disrupted neurotransmitter levels. Additionally, our further molecular mechanism study revealed that ATO-exposure increased the expression of autophagy and apoptosis related mRNA and proteins levels in the brain tissues.

CONCLUSION

Altogether, these findings provide a new insight into that ATO-exposure induced intestinal injury and aggravated neurotoxicity via the gut-brain axis.

Molecular mechanisms underlying ameliorative impact of melatonin against age-dependent chronic arsenic toxicity in rats' brains

Accumulation of random molecular damage such as oxidative DNA damage and inflammation is extremely found to be involved in the aging process. Due to extreme energy requirements and high lipid levels, the brain is more susceptible to oxidative damage during aging especially under exposure to toxic elements such as arsenic. Therefore, this study was aimed to evaluate the ameliorative effects of melatonin, as a neurohormone, on the arsenic-induced behavioral abnormalities, and the underlying mechanisms. Forty-eight rats, as young and old aged groups were exposed to 5.55 g/kg body weight arsenic for 4 weeks and then 10 mg/kg melatonin for 2 weeks. Our results showed that arsenic led to anxiety-like behavioral abnormalities in rats. Increased oxidative stress-induced damage to DNA, lipids and proteins, decreased potential of antioxidant defense system, induced apoptosis, elevated inflammation, and alteration in the histology of cortical region of brains are observed in the rats exposed to arsenic. These effects were more prominent in aged rats in comparison to young rats. Melatonin successfully attenuates arsenic induced adverse effects on the brain in both age groups. In conclusion, our study shows that melatonin has significant ameliorative impact on age-dependent cytotoxicity of arsenic in rats' brains.

Effect of Selenium on Brain Injury in Chickens with Subacute Arsenic Poisoning

The aim of this study was to investigate the effects of different doses of selenium (Se) on oxidative damage and neurotransmitter-related parameters in arsenic (As)-induced broiler brain tissue damage. Two hundred 1-day-old avian broilers were randomly divided into five groups and fed the following diets: control group (As 0.1 mg/kg + Se 0.2 mg/kg), As group (As 3 mg/kg + Se 0.2 mg/kg), low-Se group (As 3 mg/kg + Se 5 mg/kg), medium-Se group (As 3 mg/kg + Se 10 mg/kg), and high-Se group (As 3 mg/kg + Se 15 mg/kg). Glutathione (GSH), glutathione peroxidase (GSH-PX), nitric oxide (NO), nitric oxide synthase (NOS) activity, glutamate (Glu) concentration, glutamine synthetase (GS) activity, acetylcholinesterase (TchE) activity, and the apoptosis rate of brain cells were measured. The results showed that 3 mg/kg dietary As could induce oxidative damage and neurotransmitter disorder of brain tissue, increase the apoptosis rate of brain cells and cause damage to brain tissue, decrease activities of GSH and GSH-PX, decrease the contents of NO, decrease the activities of iNOS and tNOS, increase contents of Glu, and decrease activities of Gs and TchE. Compared with the As group, the Se addition of the low-Se and medium-Se groups protected against As-induced oxidative damage, neurotransmitter disorders, and the apoptosis rate of brain cells, with the addition of 10 mg/kg Se having the best effect. However, 15 mg/kg Se not only did not produce a protective effect against As damage but actually caused similar or severe damage.

Mechanisms of Metal-Induced Mitochondrial Dysfunction in Neurological Disorders

Metals are actively involved in multiple catalytic physiological activities. However, metal overload may result in neurotoxicity as it increases formation of reactive oxygen species (ROS) and elevates oxidative stress in the nervous system. Mitochondria are a key target of metal-induced toxicity, given their role in energy production. As the brain consumes a large amount of energy, mitochondrial dysfunction and the subsequent decrease in levels of ATP may significantly disrupt brain function, resulting in neuronal cell death and ensuing neurological disorders. Here, we address contemporary studies on metal-induced mitochondrial dysfunction and its impact on the nervous system.

Coenzyme Q10 protected against arsenite and enhanced the capacity of 2,3-dimercaptosuccinic acid to ameliorate arsenite-induced toxicity in mice

BACKGROUND

Arsenic poisoning affects millions of people. The inorganic forms of arsenic are more toxic. Treatment for arsenic poisoning relies on chelation of extracellularly circulating arsenic molecules by 2,3-dimecaptosuccinic acid (DMSA). As a pharmacological intervention, DMSA is unable to chelate arsenic molecules from intracellular spaces. The consequence is continued toxicity and cell damage in the presence of DMSA. A two-pronged approach that removes extracellular arsenic, while protecting from the intracellular arsenic would provide a better pharmacotherapeutic outcome. In this study, Coenzyme Q10 (CoQ10), which has been shown to protect from intracellular organic arsenic, was administered separately or with DMSA; following oral exposure to sodium meta-arsenite (NaAsO2) - a very toxic trivalent form of inorganic arsenic. The aim was to determine if CoQ10 alone or when co-administered with DMSA would nullify arsenite-induced toxicity in mice.

METHODS

Group one represented the control; the second group was treated with NaAsO2 (15 mg/kg) daily for 30 days, the third, fourth and fifth groups of mice were given NaAsO2 and treated with 200 mg/kg CoQ10 (30 days) and 50 mg/kg DMSA (5 days) either alone or in combination.

RESULTS

Administration of CoQ10 and DMSA resulted in protection from arsenic-induced suppression of RBCs, haematocrit and hemoglobin levels. CoQ10 and DMSA protected from arsenic-induced alteration of WBCs, basophils, neutrophils, monocytes, eosinophils and platelets. Arsenite-induced dyslipidemia was nullified by administration of CoQ10 alone or in combination with DMSA. Arsenite induced a drastic depletion of the liver and brain GSH; that was significantly blocked by CoQ10 and DMSA alone or in combination. Exposure to arsenite resulted in significant elevation of liver and kidney damage markers. The histological analysis of respective organs confirmed arsenic-induced organ damage, which was ameliorated by CoQ10 alone or when co-administered with DMSA. When administered alone, DMSA did not prevent arsenic-driven tissue damage.

CONCLUSIONS

Findings from this study demonstrate that CoQ10 and DMSA separately or in a combination, significantly protect against arsenic-driven toxicity in mice. It is evident that with further pre-clinical and clinical studies, an adjunct therapy that incorporates CoQ10 alongside DMSA may find applications in nullifying arsenic-driven toxicity.

Physiochemical characterization and toxicity assessment of colloidal mercuric formulation-'Sivanar amirtham'

The study aims to characterize and understand the toxicological effects of colloidal mercuric formulation. The physiochemical characterization was carried out using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Energy dispersive X-ray microanalysis system (EDS), Inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), Zeta potential, Brunauer-Emmett-Teller (BET) and electron microscopy. Based on the physiochemical characterizations, the pairwise relationship between the parameters such as size, surface area, surface charge, reactivity and band gap energy were described. The biological effects of the sample were studied by both in vitro and in vivo assays. The in vitro cytotoxicity assay confirmed that the colloidal mercuric formulation was effective against cancer cells (MCF-7) and less toxic to normal cells (Hek 293). The formulation was effective against MCF-7 with more than 85% of apoptotic and necrotic cells, positive for PI staining when treated with 100 μg/mL. The inflammatory response on the macrophage cell lines was studied. The colloidal mercuric formulation upregulated the expression of TGF-β, IL-6 and TNF-α, due to the presence of arsenic and other organic compounds such as piperine. The in vivo developmental toxicity was observed in Zebrafish hampered growth and survival in a dose and time dependent manner. The formulation was safe at lower concentration and exhibit a dose and time dependent toxicity. Based on the results obtained, it is confirmed that the selective toxicity towards MCF-7 cells is promising to develop an effective formulation for the treatment of cancer, provided more such proofs obtained from in vivo experiments.

Redox Homeostasis in Poultry: Regulatory Roles of NF-κB

Redox biology is a very quickly developing area of modern biological sciences, and roles of redox homeostasis in health and disease have recently received tremendous attention. There are a range of redox pairs in the cells/tissues responsible for redox homeostasis maintenance/regulation. In general, all redox elements are interconnected and regulated by various means, including antioxidant and vitagene networks. The redox status is responsible for maintenance of cell signaling and cell stress adaptation. Physiological roles of redox homeostasis maintenance in avian species, including poultry, have received limited attention and are poorly characterized. However, for the last 5 years, this topic attracted much attention, and a range of publications covered some related aspects. In fact, transcription factor Nrf2 was shown to be a master regulator of antioxidant defenses via activation of various vitagenes and other protective molecules to maintain redox homeostasis in cells/tissues. It was shown that Nrf2 is closely related to another transcription factor, namely, NF-κB, responsible for control of inflammation; however, its roles in poultry have not yet been characterized. Therefore, the aim of this review is to describe a current view on NF-κB functioning in poultry with a specific emphasis to its nutritional modulation under various stress conditions. In particular, on the one hand, it has been shown that, in many stress conditions in poultry, NF-κB activation can lead to increased synthesis of proinflammatory cytokines leading to systemic inflammation. On the other hand, there are a range of nutrients/supplements that can downregulate NF-κB and decrease the negative consequences of stress-related disturbances in redox homeostasis. In general, vitagene-NF-κB interactions in relation to redox balance homeostasis, immunity, and gut health in poultry production await further research.

Chronic arsenic exposure induces the time-dependent modulation of inflammation and immunosuppression in spleen

Background

Arsenic exposure has become a matter of worldwide concern, which is associated with immune-related diseases. However, little is known about its effect on inflammatory immune-related homeostasis. The purpose of our study was to understand the potential tuning of above responses exerted by chronic arsenic exposure.

Methods

Kunming mice were treated with 25 and 50 mg/L sodium arsenite for 1, 3 and 12 months via drinking water. At different endpoints of arsenic exposure, all animals and the whole spleen of the mice were weighed. The total arsenic levels of spleen were determined by the HPLC-HG-AFS method. Splenic NF-κB, MAPK and NRF2 protein levels by treatment of 25 mg/L NaAsO₂ for 1, 3 and 12 months and 25 mg/L and 50 mg/L NaAsO₂ for 12 months were assessed by western blot. Total RNA of spleen was isolated and relative mRNA levels of Foxp3, Il-10, Tnf-α, Il-6, Ifn-γ, Il-1β and Il-12 were measured by real-time PCR.

Results

Our results shown that NF-κB were continuously activated with treatment of 25 mg/L arsenic from 1, 3 to 12 months and 50 mg/L arsenic for 12 months. The transcription factor Foxp3 increased at 1 month but decreased at 3 and 12 months no matter 25 or 50 mg/L arsenic exposure. However, cytokine Il-10 always showed increased trend in mice treated with 25 or 50 mg/L arsenic for 1, 3 and 12 months. The transcriptional profiles of Tnf-α, Il-1β, Il-6, Ifn-γ and Il-12 revealed transient elevation at 1 and 3 months but shown significant decrease at 12 months on the whole. In addition, the sustained activation of inflammatory MAPK and anti-oxidative Nrf2 signaling pathways were observed in mice exposed to arsenic for 1, 3 and 12 months.

Conclusion

In summary, our experiment in vivo suggested chronic arsenic exposure induces the time-dependent modulation of the inflammation and immunosuppression in spleen, which may be related to the activation of Tregs induced by MAPK/NF-κB as well as the increased transcription level of Foxp3 and Il-10.

Tenacissoside H exerts an anti-inflammatory effect by regulating the nf-κb and p38 pathways in zebrafish

Marsdenia tenacissima exhibits biological activity with heat-clearing and detoxifying properties, relieving coughs and asthma and exerting anticancer and anti-HIV effects. Tenacissioside H (TH) is a Chinese medicine monomer extracted from the dried stem of Marsdenia tenacissima. We investigated the in vivo anti-inflammatory activity of TH using three different zebrafish inflammation models: local inflammation induced by tail cutting, acute inflammation induced by CuSO_4, and systemic inflammation induced by lipopolysaccharide (LPS). Real time-polymerase chain reaction (RT-PCR) was used to elucidate the mechanism of TH action against LPS-induced inflammatory responses. Our results showed TH significantly reduced the number of macrophages in the injured zebrafish tail, inhibited CuSO₄-induced migration of macrophages toward the neural mound, and decreased the distribution of macrophages in tail fin compared to LPS-treated group. Furthermore, TH inhibits LPS-induced inflammation responses in zebrafish by modulating the nuclear factor κB (nf-κb) and p38 pathways to regulate inflammatory cytokines, such as tumor necrosis factor-α (tnf-α), cyclooxygenase (cox-2), interleukin-1b (il-1b), interleukin-8 (il-8), interleukin-10 (il-10), nitric oxide synthase (nos2b) and prostaglandin E synthase (ptges). In conclusion, TH possesses anti-inflammation activity via the regulation of the nf-κb and p38 pathways. This finding provides a reference for the clinical application of Xiaoaiping (the trade name of Marsdenia tenacissima extract).

Synergistic effect of copper and arsenic upon oxidative stress, inflammation and autophagy alterations in brain tissues of Gallus gallus

Arsenic or copper is one of the most highly toxic pollution that can cause dysfunction to brains, however, the exact mechanism remains unclear. The aim of the study is to investigate the mechanisms of arsenic or/and copper-induced oxidative stress, inflammation and autophagy in chicken brains and elucidate the interactions between arsenic and copper. A total of 72 1-day-old Hy-line chickens were divided into four groups (18 chickens per group) treated with 30mg/kg arsenic trioxide (As₂O₃) or/and 300mg/kg copper sulfate (CuSO₄) for 12weeks. Histological signs of inflammation were found in the cerebrum, cerebellum and brainstem exposure to arsenic or/and copper. The malondialdehyde (MDA) content were up-regulation, whereas oxidative damage parameters total antioxidant capacity (T-AOC), glutathione (GSH), the inhibition ability of hydroxyl radical (OH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly decreased (P<0.05). The mRNA levels and protein expressions of inflammation markers, such as nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) and prostaglandin E synthase (PTGEs) were significantly increased (P<0.05). The mRNA levels and protein expressions of autophagy markers including phosphatidylinositol 3-kinase (PI3K), Akt, autophagy-related gene 5 (ATG5), microtubule-associated protein light chains 3 (LC3), ATG4B, and Becline1 in different regions of brains were up-regulation (P<0.05), except the mammalian target of rapamycin complex (mTORC). In conclusion, we speculated that arsenic or copper could induce oxidative stress, inflammation and autophagy in chicken brains, and there may have a synergistic effect between copper and arsenic.