Perfluorooctane sulfonate mediates microglial activation and secretion of TNF-α through Ca2+-dependent PKC-NF-кB signaling

Per- and polyfluoroalkyl substances alter innate immune function: evidence and data gaps

Per- and polyfluoroalkyl substances (PFASs) are a large class of compounds used in a variety of processes and consumer products. Their unique chemical properties make them ubiquitous and persistent environmental contaminants while also making them economically viable and socially convenient. To date, several reviews have been published to synthesize information regarding the immunotoxic effects of PFASs on the adaptive immune system. However, these reviews often do not include data on the impact of these compounds on innate immunity. Here, current literature is reviewed to identify and incorporate data regarding the effects of PFASs on innate immunity in humans, experimental models, and wildlife. Known mechanisms by which PFASs modulate innate immune function are also reviewed, including disruption of cell signaling, metabolism, and tissue-level effects. For PFASs where innate immune data are available, results are equivocal, raising additional questions about common mechanisms or pathways of toxicity, but highlighting that the innate immune system within several species can be perturbed by exposure to PFASs. Recommendations are provided for future research to inform hazard identification, risk assessment, and risk management practices for PFASs to protect the immune systems of exposed organisms as well as environmental health.

New insights into the downregulation of cytochrome P450 2E1 via nuclear factor κB-dependent pathways in immune-mediated liver injury

The extent of immune-mediated hepatic damage (such as in viral hepatitis) is characterised by the downregulation of cytochrome P450s (CYPs), a class of drug-metabolising enzymes. However, whether this downregulation aids liver cells in maintaining their homeostasis or whether the damage is aggravated remains largely unexplored. Herein, we evaluated the effects of phosphorylation mediated by the protein kinase C (PKC)/cAMP-response element binding protein (CREB) and nitration mediated by inducible nitric oxide synthase (iNOS) on the downregulation of CYP2E1 during immune-mediated liver injury. Additionally, we investigated the regulatory mechanism mediated by the nuclear factor κB (NF-κB). The rat model of immune-mediated liver injury was replicated by administering a single i.v. injection of Bacillus Calmette-Guerin (BCG, 125 mg/kg) vaccine and three i.p. injections of ammonium pyrrolidine dithiocarbamate (25, 50, 100 mg/kg/d, days 11, 12, and 13); blood was then collected on day 14. Subsequently, the livers were extracted to identify the different pharmacokinetic and biochemical indicators involved in the process. Our study reports new findings on the dependence between PKC-mediated CREB phosphorylation in the anti-inflammatory pathway and nitration emergency induced by iNOS in pro-inflammatory pathways in the NF-κB pathway. The interaction of these two pathways leads to the downregulation and recovery of CYP2E1, thus alleviating inflammation and nitration stress. Our results confirm that BCG-mediated downregulation of CYP2E1 is linked to iNOS-induced nitration and PKC/NF-κB-mediated CREB phosphorylation, and that NF-κB is an important molecular target in this process. These findings suggest that the downregulation of CYP2E1 may be an autonomous process characteristic of liver cells, helping them adapt to environmental changes, alleviate further hypoxia in inflamed tissues, and minimise exposure to toxic and harmful metabolites.

Hippocampal Proteomics Reveals the Role of Glutamatergic Synapse Activation in the Depression Induced by Perfluorooctane Sulfonate

Perfluorooctane sulfonate (PFOS), a new type of persistent organic pollutant in the environment of water, has drawn significant attention in recent years due to its widespread prevalence and high toxicity. Neurotoxicity is regarded as one of the major toxic effects of PFOS, while research studies on PFOS-induced depression and the underlying mechanisms remain scarce. In this study, behavioral tests revealed the depressive-like behaviors in PFOS-exposed male mice. Neuron damages including pyknosis and staining deepening were identified through hematoxylin and eosin staining. Then, we noticed the elevation of glutamate and proline levels as well as the decline of glutamine and tryptophan levels. Proteomics analysis identified 105 differentially expressed proteins that change in a dose-dependent manner and revealed that PFOS exposure activated the glutamatergic synapse signaling pathway, which were further confirmed by Western blot, and the data were consistent with the findings of the proteomics analysis. Additionally, the downstream signaling cyclic AMP-responsive element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) and synaptic plasticity-related postsynaptic density protein 95, synaptophysin, were downregulated. Our results highlight that PFOS exposure may inhibit the synaptic plasticity of the hippocampus via glutamatergic synapse and the CREB/BDNF signaling pathway to cause depressive-like behaviors in male mice.

Consideration of pathways for immunotoxicity of per- and polyfluoroalkyl substances (PFAS)

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are of public health concern, because of their ubiquitous and extremely persistent occurrence, and depending on their structure, their bio-accumulative, mobile and toxic properties. Human health effects associated with exposure to PFAS include adverse effects on the immune system. In 2020, EFSA (the European Food Safety Authority) defined adverse effects on the immune system as the most critical effect for human health risk assessment, based on reduced antibody responses to childhood vaccines and similar effects observed in experimental animal studies. Likewise, the U.S. EPA (Environmental Protection Agency) considers PFAS-induced immunotoxicity, especially in children, as the critical effect for risk assessment. However, the mechanisms by which antibody concentrations are impacted are not completely understood. Furthermore, other targets of the immune system functions have been reported in the literature.

OBJECTIVE

The aim of this review is to explore PFAS-associated immune-related effects. This includes, relevant mechanisms that may underlie the observed effects on the immune system, immunosuppression as well as immunoenhancement, such as i) modulation of cell signalling and nuclear receptors, such as NF-κB and PPARs; ii) alteration of calcium signalling and homoeostasis in immune cells; iii) modulation of immune cell populations; iv) oxidative stress and v) impact on fatty acid metabolism & secondary effects on the immune system.

METHODS

A literature research was conducted using three databases (Web of Science, PubMed, and Scopus), which were searched in July 2021 for relevant studies published in the time frame from 2018 to 2021. In total, 487 publications were identified as potentially eligible and following expert-based judgement, articles relevant for mechanisms of PFAS induced immunotoxicity are discussed.

CONCLUSIONS

Taken together, we show that there is substantial evidence from both in vitro and in vivo experimental as well as epidemiological studies, supporting that various PFAS, not only PFOA and PFOS, affect multiple aspects of the immune system. Timing of exposure is critical, because the developing immune system is especially vulnerable to toxic insults, resulting in a higher risk of particularly adverse immune effects but also other organs later in life.

Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework

Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.

The SH-SY5Y human neuroblastoma cell line, a relevant in vitro cell model for investigating neurotoxicology in human: focus on organic pollutants

Investigation of the toxicity triggered by chemicals on the human brain has traditionally relied on approaches using rodent in vivo models and in vitro cell models including primary neuronal cultures and cell lines from rodents. The issues of species differences between humans and rodents, the animal ethical concerns and the time and cost required for neurotoxicity studies on in vivo animal models, do limit the use of animal-based models in neurotoxicology. In this context, human cell models appear relevant in elucidating cellular and molecular impacts of neurotoxicants and facilitating prioritization of in vivo testing. The SH-SY5Y human neuroblastoma cell line (ATCC® CRL-2266^TM) is one of the most used cell lines in neurosciences, either undifferentiated or differentiated into neuron-like cells. This review presents the characteristics of the SH-SY5Y cell line and proposes the results of a systematic review of literature on the use of this in vitro cell model for neurotoxicity research by focusing on organic environmental pollutants including pesticides, 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), flame retardants, PFASs, parabens, bisphenols, phthalates, and PAHs. Organic environmental pollutants are widely present in the environment and increasingly known to cause clinical neurotoxic effects during fetal & child development and adulthood. Their effects on cultured SH-SY5Y cells include autophagy, cell death (apoptosis, pyroptosis, necroptosis, or necrosis), increased oxidative stress, mitochondrial dysfunction, disruption of neurotransmitter homeostasis, and alteration of neuritic length. Finally, the inherent advantages and limitations of the SH-SY5Y cell model are discussed in the context of chemical testing.

Membrane polarization in non-neuronal cells as a potential mechanism of metabolic disruption by depolarizing insecticides

A significant rise in the incidence of obesity and type 2 diabetes has occurred worldwide in the last two decades. Concurrently, a growing body of evidence suggests a connection between exposure to environmental pollutants, particularly insecticides, and the development of obesity and type 2 diabetes. This review summarizes key evidence of (1) the presence of different types of neuronal receptors - target sites for neurotoxic insecticides - in non-neuronal cells, (2) the activation of these receptors in non-neuronal cells by membrane-depolarizing insecticides, and (3) changes in metabolic functions, including lipid and glucose accumulation, associated with changes in membrane potential. Based on these findings, we propose that changes in membrane potential (V_mem) by certain insecticides serve as a novel regulator of lipid and glucose metabolism in non-excitable cells associated with obesity and type 2 diabetes.

Review of the development of BTK inhibitors in overcoming the clinical limitations of ibrutinib

Bruton's tyrosine kinase (BTK) regulates multiple important signaling pathways and plays a key role in the proliferation, survival, and differentiation of B-lineage cells and myeloid cells. BTK is a promising target for the treatment of hematologic malignancies. Ibrutinib, the first-generation BTK inhibitor, was approved to treat several B-cell malignancies. Despite the remarkable potency and efficacy of ibrutinib against various lymphomas and leukemias in the clinics, there are also some clinical limitations, such as off-target toxicities and primary/acquired drug resistance. As strategies to overcome these challenges, second- and third-generation BTK inhibitors, BTK-PROTACs, as well as combination therapies have been explored. In this review, we summarize clinical developments of the first-, second- and third-generation BTK inhibitors, as well as recent advances in BTK-PROTACs and ibrutinib-based combination therapies.

Perinatal exposure to endocrine disrupting chemicals and neurodevelopment: How articles of daily use influence the development of our children

Substances that interfere with the body's hormonal balance or their function are called endocrine disrupting chemicals (EDCs). Many EDCs are ubiquitous in the environment and are an unavoidable aspect of daily life, including during early embryogenesis. Developmental exposure to these chemicals is of critical relevance, as EDCs can permanently alter developmental programs, including those that pattern and wire the brain. Of emerging interest is how these chemicals may also affect the immune response, given the cross-talk between the endocrine and immune systems. As brain development is strongly dependent on hormones including thyroid, androgens, and estrogens, and can also be affected by immunomodulation, this complicated interplay may have long-lasting neurodevelopmental consequences. This review focuses on data available from human cohorts, in vivo models, and in vitro assays regarding the impact of EDCs after a gestational and/or lactational exposure, and how they may impact the immune system and/or neurodevelopment.

Protective Effects of Cinnamaldehyde against Mesenteric Ischemia-Reperfusion-Induced Lung and Liver Injuries in Rats

The aim of this study was to characterize and reveal the protective effects of cinnamaldehyde (CA) against mesenteric ischemia-reperfusion- (I/R-) induced lung and liver injuries and the related mechanisms. Sprague-Dawley (SPD) rats were pretreated for three days with 10 or 40 mg/kg/d, ig of CA, and then induced with mesenteric ischemia for 1 h and reperfusion for 2 h. The results indicated that pretreatment with 10 or 40 mg/kg of CA attenuated morphological damage in both lung and liver tissues of mesenteric I/R-injured rats. CA pretreatment significantly restored the levels of aspartate transaminase (AST) and alanine transaminase (ALT) in mesenteric I/R-injured liver tissues, indicating the improvement of hepatic function. CA also significantly attenuated the inflammation via reducing myeloperoxidase (MOP) activity and downregulating the expression of inflammation-related proteins, including interleukin-6 (IL-6), interleukin-1β (IL-1β), cyclooxygenase-2 (Cox-2), and tumor necrosis factor receptor type-2 (TNFR-2) in both lung and liver tissues of mesenteric I/R-injured rats. Pretreatment with CA significantly downregulated nuclear factor kappa B- (NF-κB-) related protein expressions (NF-κB p65, NF-κB p50, I kappa B alpha (IK-α), and inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ)) in both lung and liver tissues of mesenteric I/R-injured rats. CA also significantly downregulated the protein expression of p53 family members, including caspase-3, caspase-9, Bax, and p53, and restored Bcl-2 in both lung and liver tissues of mesenteric I/R-injured rats. CA pretreatment significantly reduced TUNEL-apoptotic cells and significantly inhibited p53 and NF-κB p65 nuclear translocation in both lung and liver tissues of mesenteric I/R-injured rats. CA neither induced pulmonary and hepatic histological alterations nor affected the parameters of inflammation and apoptosis in sham rats. We conclude that CA alleviated mesenteric I/R-induced pulmonary and hepatic injuries via attenuating apoptosis and inflammation through inhibition of NF-κB and p53 pathways in rats, suggesting the potential role of CA in remote organ ischemic injury protection.

Mechanism of immunosuppression in zebrafish (Danio rerio) spleen induced by environmentally relevant concentrations of perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) has been identified as a new persistent organic pollutant. This pollutant is ubiquitous in water and environments. Although PFOA is toxic to fishes, the precise immunotoxicological mechanism remains unclear. In this study, HPLC-MS analysis proved that PFOA can accumulate in the spleen of zebrafish. As comparison of 7-day and 14-day data, the cumulative content in the spleen significantly increased by 26% even in the 0.1 mg/L PFOA-treated group. Morphological observations revealed that PFOA can damage immune cells in zebrafish spleen by inducing vacuolization, lipofuscin granule production, and mitochondrial swelling. The Toll-like receptor 2 (TLR2)/myeloid differentiation factor 88 (myd88)/NF-κB (P65) pathway can mediate the mRNA expression levels of interferon (IFN) and B cell-activating factor (BAFF); immunoglobulin (Ig) secretion is further regulated. RT-PCR results indicated that the expression levels of P65 and IFN in the 1 mg/L group after PFOA exposure for 7 d increased by 4.03- and 3.28-fold, respectively, in a dose-dependent manner compared with those of the control group. The linear correlation coefficient (r²) was analyzed, and the results indicated that the Ig-mediated pathway can be affected by PFOA. For example, the r² between IgD and P65 decreased from 0.641 (7 d) to 0.295 (14 d) after the cells were exposed to PFOA for a prolonged time; the r² between IgD and IFN increased from 0.562 (7 d) to 0.808 (14 d). The triangle plot method strongly demonstrated that increased PFOA concentration and prolonged exposure to PFOA can inhibit Ig secretion. Therefore, immune organs, particularly the spleen, of zebrafish are vulnerable to PFOA. These results can help to improve the understanding of the possible noncarcinogenic risk mechanisms induced by PFOA.

Heavy Metal-Induced Cerebral Small Vessel Disease: Insights into Molecular Mechanisms and Possible Reversal Strategies

Heavy metals are considered a continuous threat to humanity, as they cannot be eradicated. Prolonged exposure to heavy metals/metalloids in humans has been associated with several health risks, including neurodegeneration, vascular dysfunction, metabolic disorders, cancer, etc. Small blood vessels are highly vulnerable to heavy metals as they are directly exposed to the blood circulatory system, which has comparatively higher concentration of heavy metals than other organs. Cerebral small vessel disease (CSVD) is an umbrella term used to describe various pathological processes that affect the cerebral small blood vessels and is accepted as a primary contributor in associated disorders, such as dementia, cognitive disabilities, mood disorder, and ischemic, as well as a hemorrhagic stroke. In this review, we discuss the possible implication of heavy metals/metalloid exposure in CSVD and its associated disorders based on in-vitro, preclinical, and clinical evidences. We briefly discuss the CSVD, prevalence, epidemiology, and risk factors for development such as genetic, traditional, and environmental factors. Toxic effects of specific heavy metal/metalloid intoxication (As, Cd, Pb, Hg, and Cu) in the small vessel associated endothelium and vascular dysfunction too have been reviewed. An attempt has been made to highlight the possible molecular mechanism involved in the pathophysiology, such as oxidative stress, inflammatory pathway, matrix metalloproteinases (MMPs) expression, and amyloid angiopathy in the CSVD and related disorders. Finally, we discussed the role of cellular antioxidant defense enzymes to neutralize the toxic effect, and also highlighted the potential reversal strategies to combat heavy metal-induced vascular changes. In conclusion, heavy metals in small vessels are strongly associated with the development as well as the progression of CSVD. Chelation therapy may be an effective strategy to reduce the toxic metal load and the associated complications.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) acutely affect human α1β2γ2L GABAA receptor and spontaneous neuronal network function in vitro

Concerns about the neurotoxic potential of polyfluoroalkyl substances (PFAS) such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) increase, although their neurotoxic mechanisms of action remain debated. Considering the importance of the GABA_A receptor in neuronal function, we investigated acute effects of PFAS on this receptor and on spontaneous neuronal network activity. PFOS (Lowest Observed Effect Concentration (LOEC) 0.1 µM) and PFOA (LOEC 1 µM) inhibited the GABA-evoked current and acted as non-competitive human GABA_A receptor antagonists. Network activity of rat primary cortical cultures increased following exposure to PFOS (LOEC 100 µM). However, exposure of networks of human induced pluripotent stem cell (hiPSC)-derived neurons decreased neuronal activity. The higher sensitivity of the α₁β₂γ_2L GABA_A receptor for PFAS as compared to neuronal networks suggests that PFAS have additional mechanisms of action, or that compensatory mechanisms are at play. Differences between rodent and hiPSC-derived neuronal networks highlight the importance of proper model composition. LOECs for PFAS on GABA_A receptor and neuronal activity reported here are within or below the range found in blood levels of occupationally exposed humans. For PFOS, LOECs are even within the range found in human serum and plasma of the general population, suggesting a clear neurotoxic risk.

PFOA evokes extracellular Ca2+ influx and compromises progesterone-induced response in human sperm

Perfluorooctane acid (PFOA), a persistent organic pollutant, is ubiquitously present in the environment and may detrimentally affect male reproductive health. In this study, mature human sperm were in vitro exposed to different concentrations of PFOA (0.25, 2.5 or 25 μg/ml) alone or in combination with progesterone (P4) to evaluate the toxicity and the potential mechanism of action. Exposure to high-dose PFOA (25 μg/ml) alone for 4 h caused a decline in capacity of human spermatozoa to penetrate synthetic mucus, with an increased production of reactive oxygen species (ROS). Furthermore, PFOA treatment (2.5 and 25 μg/ml) evoked a transient rise in intracellular calcium concentration [Ca²⁺]_i by activating the sperm-specific CatSper channel. However, preincubation with PFOA (2.5-25 μg/ml) for 4 h significantly suppressed P4-stimulated extracellular Ca²⁺ influx in human spermatozoa. Moreover, PFOA pretreatment at all concentrations evaluated markedly compromised P4-induced acrosome reaction and sperm penetration into viscous medium. Taken together, these results suggest that PFOA exposure may impair human sperm function through inducing oxidative stress and disturbing P4-induced Ca²⁺ signaling.

Environmentally relevant doses of tetrabromobisphenol A (TBBPA) cause immunotoxicity in murine macrophages

TBBPA is one of the main brominated flame retardants and is ubiquitous in the environment. TBBPA can directly encounter immune cells via the bloodstream, posing potential immunotoxicity. To understand the immunomodulating effect of TBBPA on macrophages, the murine macrophages, RAW 264.7, were exposed to TBBPA at environmentally relevant concentrations (1-100 nM). The results showed that TBBPA at the selected concentrations did not alter cell viability of RAW 264.7 cells with or without LPS stimulation. TBBPA upregulated the expression of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α, whereas it attenuated the LPS-stimulated expression of these pro-inflammatory cytokines, and the expression of anti-inflammatory cytokines, including IL-4, IL-10, and IL-13. In addition, TBBPA reduced the mRNA levels of antigen-presenting-related genes, including H2-K2, H2-Aa, Cd80, and Cd86. Moreover, TBBPA impaired the phagocytic activity of macrophages. Furthermore, exposure to TBBPA significantly elevated the protein levels of phosphorylated NF-κB p65 (p-p65), while it reduced LPS-stimulated p-p65 protein levels. DCFH-DA staining assays showed that TBBPA caused a slight but significant elevation in reactive oxygen species levels. The data obtained in the present study demonstrated that exposure to environmentally relevant concentrations of TBBPA posed immunotoxicity in macrophages and unveiled a potential health risk of TBBPA.

PKC Mediates LPS-Induced IL-1β Expression and Participates in the Pro-inflammatory Effect of A2AR Under High Glutamate Concentrations in Mouse Microglia

Pathogens such as bacterial lipopolysaccharide (LPS) play an important role in promoting the production of the inflammatory cytokines interleukin-1 beta (IL-1β) and tumour necrosis factor-α (TNF-α) in response to infection or damage in microglia. However, whether different signalling pathways regulate these two inflammatory factors remains unclear. The protein kinase C (PKC) family is involved in the regulation of inflammation, and our previous research showed that the activation of the PKC pathway played a key role in the LPS-induced transformation of the adenosine A_2A receptor (A_2AR) from anti-inflammatory activity to pro-inflammatory activity under high glutamate concentrations. Therefore, in the current study, we investigated the role of PKC in the LPS-induced production of these inflammatory cytokines in mouse primary microglia. GF109203X, a specific PKC inhibitor, inhibited the LPS-induced expression of IL-1β messenger ribonucleic acid and intracellular protein in a dose-dependent manner. Moreover, 5 µM GF109203X prevented LPS-induced IL-1β expression but did not significantly affect LPS-induced TNF-α expression. PKC promoted IL-1β expression by regulating the activity of NF-κB but did not significantly impact the activity of ERK1/2. A_2AR activation by CGS21680, an A_2AR agonist, facilitated LPS-induced IL-1β expression through the PKC pathway at high glutamate concentrations but did not significantly affect LPS-induced TNF-α expression. Taken together, these results suggest a new direction for specific intervention with LPS-induced inflammatory factors in response to specific signalling pathways and provide a mechanism for A_2AR targeting, especially after brain injury, to influence inflammation by interfering with A_2AR.

Radix Scrophulariae extracts (harpagoside) suppresses hypoxia-induced microglial activation and neurotoxicity

Background

Hypoxia could lead to microglia activation and inflammatory mediators’ overproduction. These inflammatory molecules could amplify the neuroinflammatory process and exacerbate neuronal injury. The aim of this study is to find out whether harpagoside could reduce hypoxia-induced microglia activation.

Methods

In this study, primary microglia cells harvested from neonatal ICR mice were activated by exposure to hypoxia (1 % O₂ for 3 h). Harpagoside had been shown to be no cytotoxicity on microglia cells by MTT assay. The scavenger effect of harpagoside on hypoxia-enhanced microglial cells proliferation, associated inflammatory genes expression (COX-II, IL-1β and IL-6 genes) and NO synthesis were also examined.

Results

Hypoxia enhances active proliferation of microglial cells, while harpagoside can scavenge this effect. We find that harpagoside could scavenge hypoxia-enhanced inflammatory genes expression (COX-2, IL-1β and IL-6 genes) and NO synthesis of microglial cells. Under 3 h’ hypoxic stimulation, the nuclear contents of p65 and hypoxia inducible factor-1α (HIF-1α) significantly increase, while the cytosol IκB-α content decreases; these effects can be reversed by 1 h’s pre-incubation of 10⁻⁸ M harpagoside. Harpagoside could decrease IκB-α protein phosphorylation and inhibit p65 protein translocation from the cytosol to the nucleus, thus suppress NF-κB activation and reduce the HIF-1α generation.

Conclusion

These results suggested that the anti-inflammatory mechanism of harpagoside might be associated with the NF-κB signaling pathway. Harpagoside protect against hypoxia-induced toxicity on microglial cells through HIF-α pathway.

Beneficial effects of evodiamine on P2X(4)-mediated inflammatory injury of human umbilical vein endothelial cells due to high glucose

Evodiamine has been reported to exhibit anti-inflammatory and anti-nociceptive effects, but the underlying mechanisms remain to be defined. P2X4 receptor (P2X4R) is a subtype of ATP receptors and plays important roles in pain, inflammatory and immune responses. We aimed to investigate whether evodiamine has beneficial effects on endothelial inflammatory injury mediated by chronic high glucose condition. We found that culturing human umbilical vein endothelial cells (HUVECs) with high glucose significantly increased the expression of P2X4 receptor in HUVECs, cytosolic Ca(2+) concentrations and intracellular reactive oxygen species (ROS) while decreasing nitric oxide (NO); these effects could be reversed by evodiamine. High glucose also significantly increased the expression of the pro-inflammatory activators (NF-κB) and TNFR-ɑ, which was accompanied by the elevation of P2X4R levels. Evodiamine was able to down-regulate the elevated NF-κB, TNFR-ɑ, P2X4R and ROS, and up-regulate the decreased NO. Thus the evodiamine may exert the anti-inflammation activity on high-glucose challenge HUVEC via suppressing the P2X4R signaling pathway, exhibiting beneficial ability to protect HUVECs from glucotoxicity.