NADPH Oxidase-Derived Peroxynitrite Drives Inflammation in Mice and Human Nonalcoholic Steatohepatitis via TLR4-Lipid Raft Recruitment

Unravelling the complexities of non-alcoholic steatohepatitis: The role of metabolism, transporters, and herb-drug interactions

Nonalcoholic fatty liver disease (NAFLD) is a mainstream halting liver disease with high prevalence in North America, Europe, and other world regions. It is an advanced form of NAFLD caused by the amassing of fat in the liver and can progress to the more severe form known as non-alcoholic steatohepatitis (NASH). Until recently, there was no authorized pharmacotherapy reported for NASH, and to improve the patient's metabolic syndrome, the focus is mainly on lifestyle modification, weight loss, ensuring a healthy diet, and increased physical activity; however, the recent approval of Rezdiffra (Resmetirom) by the US FDA may change this narrative. As per the reported studies, there is an increased articulation of uptake and efflux transporters of the liver, including OATP and MRP, in NASH, leading to changes in the drug's pharmacokinetic properties. This increase leads to alterations in the pharmacokinetic properties of drugs. Furthermore, modifications in Cytochrome P450 (CYP) enzymes can have a significant impact on these properties. Xenobiotics are metabolized primarily in the liver and constitute liver enzymes and transporters. This review aims to delve into the role of metabolism, transport, and potential herb-drug interactions in the context of NASH.

Causal relationship between air pollution, lung function, gastroesophageal reflux disease, and non-alcoholic fatty liver disease: univariate and multivariate Mendelian randomization study

Background

The association between air pollution, lung function, gastroesophageal reflux disease, and Non-alcoholic fatty liver disease (NAFLD) remains inconclusive. Previous studies were not convincing due to confounding factors and reverse causality. We aim to investigate the causal relationship between air pollution, lung function, gastroesophageal reflux disease, and NAFLD using Mendelian randomization analysis.

Methods

In this study, univariate Mendelian randomization analysis was conducted first. Subsequently, Steiger testing was performed to exclude the possibility of reverse association. Finally, significant risk factors identified from the univariate Mendelian analysis, as well as important factors affecting NAFLD from previous observational studies (type 2 diabetes and body mass index), were included in the multivariable Mendelian randomization analysis.

Results

The results of the univariable Mendelian randomization analysis showed a positive correlation between particulate matter 2.5, gastroesophageal reflux disease, and NAFLD. There was a negative correlation between forced expiratory volume in 1 s, forced vital capacity, and NAFLD. The multivariable Mendelian randomization analysis indicated a direct causal relationship between gastroesophageal reflux disease (OR = 1.537, p = 0.011), type 2 diabetes (OR = 1.261, p < 0.001), and NAFLD.

Conclusion

This Mendelian randomization study confirmed the causal relationships between air pollution, lung function, gastroesophageal reflux, and NAFLD. Furthermore, gastroesophageal reflux and type 2 diabetes were identified as independent risk factors for NAFLD, having a direct causal connection with the occurrence of NAFLD.

Direct assessment of nitrative stress in lipid environments: Applications of a designer lipid-based biosensor for peroxynitrite

Lipid membranes and lipid-rich organelles are targets of peroxynitrite (ONOO-), a highly reactive species generated under nitrative stress. We report a membrane-localized phospholipid (DPPC-TC-ONOO-) that allows the detection of ONOO- in diverse lipid environments: biomimetic vesicles, mammalian cell compartments, and within the lung lining. DPPC-TC-ONOO- and POPC self-assemble to membrane vesicles that fluorogenically and selectively respond to ONOO-. DPPC-TC-ONOO-, delivered through lipid nanoparticles, allowed for ONOO- detection in the endoplasmic reticulum upon cytokine-induced nitrative stress in live mammalian cells. It also responded to ONOO- within lung tissue murine models upon acute lung injury. We observed nitrative stress around bronchioles in precision cut lung slices exposed to nitrogen mustard and in pulmonary macrophages following intratracheal bleomycin challenge. Results showed that DPPC-TC-ONOO- functions specifically toward iNOS, a key enzyme modulating nitrative stress, and offers significant advantages over its hydrophilic analog in terms of localization and signal generation.

Uric Acid: A Translational Journey in Cerebroprotection That Spanned Preclinical and Human Data

Uric acid (UA) is a strong endogenous antioxidant that neutralizes the toxicity of peroxynitrite and other reactive species on the neurovascular unit generated during and after acute brain ischemia. The realization that a rapid reduction of UA levels during an acute ischemic stroke was associated with a worse stroke outcome paved the way to investigate the value of exogenous UA supplementation to counteract the progression of redox-mediated ischemic brain damage. The long translational journey for UA supplementation recently reached a critical milestone when the results of the multicenter NIH stroke preclinical assessment network (SPAN) were reported. In a novel preclinical paradigm, 6 treatment candidates including UA supplementation were selected and tested in 6 independent laboratories following predefined criteria and strict methodological rigor. UA supplementation was the only intervention in SPAN that exceeded the prespecified efficacy boundary with male and female animals, young mice, young rats, aging mice, obese mice, and spontaneously hypertensive rats. This unprecedented achievement will allow UA to undergo clinical testing in a pivotal clinical trial through a NIH StrokeNet thrombectomy endovascular platform created to assess new treatment strategies in patients treated with mechanical thrombectomy. UA is a particularly appealing adjuvant intervention for mechanical thrombectomy because it targets the microcirculatory hypoperfusion and oxidative stress that limits the efficacy of this therapy. This descriptive review aims to summarize the translational development of UA supplementation, highlighting those aspects that likely contributed to its success. It includes having a well-defined target and mechanism of action, and an approach that simultaneously integrated rigorous preclinical assessment, with epidemiologic and preliminary human intervention studies. Validation of the clinical value of UA supplementation in a pivotal trial would confirm the translational value of the SPAN paradigm in preclinical research.

NO-IL-6/10-IL-1β axis: a new pathway in steatotic and non-steatotic liver grafts from brain-dead donor rats

Introduction

Brain death (BD) and steatosis are both risk factors for organ dysfunction or failure in liver transplantation (LT).

Material and methods

Here, we examine the role of interleukin 6 (IL- 6) and IL-10 in LT of both non-steatotic and steatotic liver recovered from donors after brain death (DBDs), as well as the molecular signaling pathways underlying the effects of such cytokines.

Results

BD reduced IL-6 levels only in nonsteatotic grafts, and diminished IL-10 levels only in steatotic ones. In both graft types, BD increased IL-1β, which was associated with hepatic inflammation and damage. IL-6 administration reduced IL-1β only in non-steatotic grafts and protected them against damage and inflammation. Concordantly, IL-1β inhibition via treatment with an IL-1 receptor antagonist caused the same benefits in non-steatotic grafts. Treatment with IL-10 decreased IL-1β only in steatotic grafts and reduced injury and inflammation specifically in this graft type. Blockading the IL-1β effects also reduced damage and inflammation in steatotic grafts. Also, blockade of IL-1β action diminished hepatic cAMP in both types of livers, and this was associated with a reduction in liver injury and inflammation, then pointing to IL-1β regulating cAMP generation under LT and BD conditions. Additionally, the involvement of nitric oxide (NO) in the effects of interleukins was evaluated. Pharmacological inhibition of NO in LT from DBDs prompted even more evident reductions of IL-6 or IL-10 in non-steatotic and steatotic grafts, respectively. This exacerbated the already high levels of IL-1β seen in LT from DBDs, causing worse damage and inflammation in both graft types. The administration of NO donors to non-steatotic grafts potentiated the beneficial effects of endogenous NO, since it increased IL-6 levels, and reduced IL-1β, inflammation, and damage. However, treatment with NO donors in steatotic grafts did not modify IL-10 or IL-1β levels, but induced more injurious effects tan the induction of BD alone, characterized by increased nitrotyrosine, lipid peroxidation, inflammation, and hepatic damage.

Conclusion

Our study thus highlights the specificity of new signaling pathways in LT from DBDs: NO-IL-6-IL-1β in non-steatotic livers and NO-IL-10-IL-1β in steatotic ones. This opens up new therapeutic targets that could be useful in clinical LT.

Targeting fibrosis, mechanisms and cilinical trials

Fibrosis is characterized by the excessive extracellular matrix deposition due to dysregulated wound and connective tissue repair response. Multiple organs can develop fibrosis, including the liver, kidney, heart, and lung. Fibrosis such as liver cirrhosis, idiopathic pulmonary fibrosis, and cystic fibrosis caused substantial disease burden. Persistent abnormal activation of myofibroblasts mediated by various signals, such as transforming growth factor, platelet-derived growth factor, and fibroblast growh factor, has been recongized as a major event in the occurrence and progression of fibrosis. Although the mechanisms driving organ-specific fibrosis have not been fully elucidated, drugs targeting these identified aberrant signals have achieved potent anti-fibrotic efficacy in clinical trials. In this review, we briefly introduce the aetiology and epidemiology of several fibrosis diseases, including liver fibrosis, kidney fibrosis, cardiac fibrosis, and pulmonary fibrosis. Then, we summarise the abnormal cells (epithelial cells, endothelial cells, immune cells, and fibroblasts) and their interactions in fibrosis. In addition, we also focus on the aberrant signaling pathways and therapeutic targets that regulate myofibroblast activation, extracellular matrix cross-linking, metabolism, and inflammation in fibrosis. Finally, we discuss the anti-fibrotic drugs based on their targets and clinical trials. This review provides reference for further research on fibrosis mechanism, drug development, and clinical trials.

Perspectives in liver redox imbalance: Toxicological and pharmacological aspects underlying iron overloading, nonalcoholic fatty liver disease, and thyroid hormone action

Oxidative stress is an imbalance between oxidants and antioxidants in favor of the oxidants, leading to a disruption of redox signaling and control, and/or molecular damage altering cellular functions. This redox imbalance may trigger different responses depending on the antioxidant potential of a given cell, the level of reactive oxygen/nitrogen species (ROS/RNS) attained and the time of exposure, with protective effects being induced at low ROS/RNS levels in acute or short-term conditions, and harmful effects after high ROS/RNS exposure in prolonged situations. Relevant conditions underlying liver redox imbalance include iron overload associated with ROS production via Fenton chemistry and the magnitude of the iron labile pool achieved, with low iron exposure inducing protective effects related to nuclear factor-κB, signal transducer and activation of transcription 3, and nuclear factor erythroid-related factor 2 (Nrf2) activation and upregulation of ferritin, hepcidin, acute-phase response and antioxidant components, whereas high iron exposure causes drastic oxidation of biomolecules, mitochondrial dysfunction, and cell death due to necrosis, apoptosis and/or ferroptosis. Redox imbalance in nonalcoholic fatty liver disease (NAFLD) is related to polyunsaturated fatty acid depletion, lipogenic factor sterol regulatory element-binding protein-1c upregulation, fatty acid oxidation-dependent peroxisome proliferator-activated receptor-α downregulation, low antioxidant factor Nrf2 and insulin resistance, a phenomenon that is exacerbated in nonalcoholic steatohepatitis triggering an inflammatory response. Thyroid hormone (T₃ ) administration determines liver preconditioning against ischemia-reperfusion injury due to the redox activation of several transcription factors, AMP-activated protein kinase, unfolded protein response and autophagy. High grade liver redox imbalance occurring in severe iron overload is adequately handled by iron chelation, however, that underlying NAFLD/NASH is currently under study in several Phase II and Phase III trials.

Environmental Microcystin exposure in underlying NAFLD-induced exacerbation of neuroinflammation, blood-brain barrier dysfunction, and neurodegeneration are NLRP3 and S100B dependent

Nonalcoholic fatty liver disease (NAFLD) has been shown to be associated with extrahepatic comorbidities including neuronal inflammation and Alzheimer's-like pathology. Environmental and genetic factors also act as a second hit to modulate severity and are expected to enhance the NAFLD-linked neuropathology. We hypothezied that environmental microcystin-LR (MC-LR), a toxin produced by harmful algal blooms of cyanobacteria, exacerbates the neuroinflammation and degeneration of neurons associated with NAFLD. Using a mouse model of NAFLD, exposed to MC-LR subsequent to the onset of fatty liver, we show that the cyanotoxin could significantly increase proinflammatory cytokine expression in the frontal cortex and cause increased expression of Lcn2 and HMGB1. The above effects were NLRP3 inflammasome activation-dependent since the use of NLRP3 knockout mice abrogated the increase in inflammation. NLRP3 was also responsible for decreased expression of the blood-brain barrier (BBB) tight junction proteins Occludin and Claudin 5 suggesting BBB dysfunction was parallel to neuroinflammation following microcystin exposure. An increased circulatory S100B release, a hallmark of astrocyte activation in MC-LR exposed NAFLD mice also confirmed BBB integrity loss, but the astrocyte activation observed in vivo was NLRP3 independent suggesting an important role of a secondary S100B mediated crosstalk. Mechanistically, conditioned medium from reactive astrocytes and parallel S100B incubation in neuronal cells caused increased inducible NOS, COX-2, and higher BAX/ Bcl2 protein expression suggesting oxidative stress-mediated neuronal cell apoptosis crucial for neurodegeneration. Taken together, MC-LR exacerbated neuronal NAFLD-linked comorbidities leading to cortical inflammation, BBB dysfunction, and neuronal apoptosis.

Nonalcoholic fatty liver disease (NAFLD) from pathogenesis to treatment concepts in humans

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) comprises hepatic alterations with increased lipid accumulation (steatosis) without or with inflammation (nonalcoholic steatohepatitis, NASH) and/or fibrosis in the absence of other causes of liver disease. NAFLD is developing as a burgeoning health challenge, mainly due to the worldwide obesity and diabetes epidemics.

SCOPE OF REVIEW

This review summarizes the knowledge on the pathogenesis underlying NAFLD by focusing on studies in humans and on hypercaloric nutrition, including effects of saturated fat and fructose, as well as adipose tissue dysfunction, leading to hepatic lipotoxicity, abnormal mitochondrial function, and oxidative stress, and highlights intestinal dysbiosis. These mechanisms are discussed in the context of current treatments targeting metabolic pathways and the results of related clinical trials.

MAJOR CONCLUSIONS

Recent studies have provided evidence that certain conditions, for example, the severe insulin-resistant diabetes (SIRD) subgroup (cluster) and the presence of an increasing number of gene variants, seem to predispose for excessive risk of NAFLD and its accelerated progression. Recent clinical trials have been frequently unsuccessful in halting or preventing NAFLD progression, perhaps partly due to including unselected cohorts in later stages of NAFLD. On the basis of this literature review, this study proposed screening in individuals with the highest genetic or acquired risk of disease progression, for example, the SIRD subgroup, and developing treatment concepts targeting the earliest pathophysiolgical alterations, namely, adipocyte dysfunction and insulin resistance.

Astragalin Retards Atherosclerosis by Promoting Cholesterol Efflux and Inhibiting the Inflammatory Response via Upregulating ABCA1 and ABCG1 Expression in Macrophages

ABSTRACT

Lipid metabolism disorder and inflammatory response are considered to be the major causes of atherosclerogenesis. Astragalin, the most important functional component of flavonoid obtained from persimmon leaves, has the hypolipidemic effects. However, it is unknown, how astragalin protects against atherosclerosis. The aim of this study was to observe the effects of astragalin on cholesterol efflux and inflammatory response and to explore the underlying mechanisms. Our results showed that astragalin upregulated the expression of ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1), promoted cholesterol efflux, and suppressed foam cell formation. Inhibition of the PPARγ/LXRα pathway abrogated the promotive effects of astragalin on both transporter expression and cholesterol efflux. In addition, treatment of astragalin markedly decreased the secretion of inflammatory factors, including interleukin 6, monocyte chemotactic protein 1, tumor necrosis factor α, and interleukin 1β. Mechanistically, astragalin upregulated ABCA1 and ABCG1 expression, which in turn reduced TLR4 surface levels and inhibited NF-κB nuclear translocation. Consistently, astragalin reduced atherosclerotic plaque area in apoE-/- mice. Taken together, these findings suggest that astragalin protects against atherosclerosis by promoting ABCA1- and ABCG1-mediated cholesterol efflux and inhibiting proinflammatory mediator release.

Higher intestinal and circulatory lactate associated NOX2 activation leads to an ectopic fibrotic pathology following microcystin co-exposure in murine fatty liver disease

Clinical studies implicated an increased risk of intestinal fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). Our previous studies have shown that microcystin-LR (MC-LR) exposure led to altered gut microbiome and increased abundance of lactate producing bacteria and intestinal inflammation in underlying NAFLD. This led us to further investigate the effects of the MC-LR, a PP2A inhibitor in activating the TGF-β fibrotic pathway in the intestines that might be mediated by increased lactate induced redox enzyme NOX2. Exposure to MC-LR led to higher lactate levels in circulation and in the intestinal content. The higher lactate levels were associated with NOX2 activation in vivo that led to increased Smad2/3-Smad4 co-localization and high alpha-smooth muscle actin (α-SMA) immunoreactivity in the intestines. Mechanistically, primary mouse intestinal epithelial cells treated with lactate and MC-LR separately led to higher NOX2 activation, phosphorylation of TGFβR1 receptor and subsequent Smad 2/3-Smad4 co-localization inhibitable by apocynin (NOX2 inhibitor), FBA (a peroxynitrite scavenger) and DMPO (a nitrone spin trap), catalase and superoxide dismutase. Inhibition of NOX2-induced redox signaling also showed a significant decrease in collagen protein thus suggesting a strong redox signaling induced activation of an ectopic fibrotic manifestation in the intestines. In conclusion, the present study provides mechanistic insight into the role of microcystin in dysbiosis-linked lactate production and subsequently advances our knowledge in lactate-induced NOX2 exacerbation of the cell differentiation and fibrosis in the NAFLD intestines.

Chemical modification of pro-inflammatory proteins by peroxynitrite increases activation of TLR4 and NF-κB: Implications for the health effects of air pollution and oxidative stress

Environmental pollutants like fine particulate matter can cause adverse health effects through oxidative stress and inflammation. Reactive oxygen and nitrogen species (ROS/RNS) such as peroxynitrite can chemically modify proteins, but the effects of such modifications on the immune system and human health are not well understood. In the course of inflammatory processes, the Toll-like receptor 4 (TLR4) can sense damage-associated molecular patterns (DAMPs). Here, we investigate how the TLR4 response and pro-inflammatory potential of the proteinous DAMPs α-Synuclein (α-Syn), heat shock protein 60 (HSP60), and high-mobility-group box 1 protein (HMGB1), which are relevant in neurodegenerative and cardiovascular diseases, changes upon chemical modification with peroxynitrite.

For the peroxynitrite-modified proteins, we found a strongly enhanced activation of TLR4 and the pro-inflammatory transcription factor NF-κB in stable reporter cell lines as well as increased mRNA expression and secretion of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-8 in human monocytes (THP-1). This enhanced activation of innate immunity via TLR4 is mediated by covalent chemical modifications of the studied DAMPs.

Our results show that proteinous DAMPs modified by peroxynitrite more potently amplify inflammation via TLR4 activation than the native DAMPs, and provide first evidence that such modifications can directly enhance innate immune responses via a defined receptor. These findings suggest that environmental pollutants and related ROS/RNS may play a role in promoting acute and chronic inflammatory disorders by structurally modifying the body's own DAMPs. This may have important consequences for chronic neurodegenerative, cardiovascular or gastrointestinal diseases that are prevalent in modern societies, and calls for action, to improve air quality and climate in the Anthropocene.

•

Pollutants and oxidative stress can cause protein nitration and oligomerization.

•

Peroxynitrite amplifies inflammatory potential of disease-related proteins in vitro.

•

Chemical modification of damage-associated molecular patterns (DAMPs).

•

Positive feedback of modified DAMPs via pattern recognition receptor (TLR4).

•

Air pollution may promote inflammatory disorders in the Anthropocene.

Five Constituents in Psoralea corylifolia L. Attenuate Palmitic Acid-Induced Hepatocyte Injury via Inhibiting the Protein Kinase C-α/Nicotinamide-Adenine Dinucleotide Phosphate Oxidase Pathway

Psoralea corylifolia L. (PC) is a traditional Chinese herb used to treat yang deficiency of the spleen and kidney in pediatric disease. Our previous studies have found that PC can alleviate the liver oxidative stress of juvenile mice with nonalcoholic steatohepatitis (NASH), and its mechanism is related to the inhibition of the protein kinase C-α (PKC-α)/nicotinamide-adenine dinucleotide phosphate oxidase (NOX) signaling pathway. The aim of this study was to confirm the aforementioned drug target in vitro and to conduct preliminary screening for some effective compounds of PC on the treatment of NASH. A primary hepatocyte model of non alcoholic fatty liver disease was established by palmitic acid. The existence of Psoralen, Isopsoralen, Neobavaisoflavone, Isobavachalcone, and Bakuchiol were identified by ultra-performance liquid chromatography. Then, five PC compounds were administered. Intracellular triglyceride and total cholesterol content, the cell supernatant alanine aminotransferase and aspartate aminotransferase, and hepatocellular superoxide anion were examined. The changes of PKC-α/NOX signaling pathways in hepatocytes were also determined. Furthermore, PKC-α activator phorbol 12-myristate 13-acetate was administered for 4 h before Psoralen intervention was conducted again to detect the changes of PKC-α/NOX signaling pathways. Our data demonstrated that Psoralen, Isopsoralen, and Isobavachalcone decreased intracellular content of triglyceride while all five PC compounds improved hepatocellular total cholesterol accumulation and hepatocyte damage in palmitic acid-induced primary hepatocyte model of non alcoholic fatty liver disease. All five PC compounds could also reduce hepatocytic superoxide anion levels, nicotinamide-adenine dinucleotide phosphate/reduced nicotinamide-adenine dinucleotide phosphate ratio, NOX activity as well as p47^phox protein expression and PKCα activation in hepatocytes. Psoralen exhibited the best efficacy but the effectiveness was lost when pre-stimulated by phorbol 12-myristate 13-acetate. The results suggest that Psoralen, Isopsoralen, and Isobavachalcone could improve hepatocyte steatosis; five PC compounds could ameliorate hepatocyte injury, relieve oxidative stress, and downregulate the PKC-α/NOX signaling pathway of hepatocytes. In addition, Psoralen exhibits the best efficacy and a prospective PKC-α inhibitor pharmaceutical activity.

Saturated Fatty Acids in Obesity-Associated Inflammation

Obesity is a major risk factor for the development of various pathological conditions including insulin resistance, diabetes, cardiovascular diseases, and non-alcoholic fatty liver disease (NAFLD). Central to these conditions is obesity-associated chronic low-grade inflammation in many tissues including adipose, liver, muscle, kidney, pancreas, and brain. There is increasing evidence that saturated fatty acids (SFAs) increase the phosphorylation of MAPKs, enhance the activation of transcription factors such as nuclear factor (NF)-κB, and elevate the expression of inflammatory genes. This paper focuses on the mechanisms by which SFAs induce inflammation. SFAs may induce the expression inflammatory genes via different pathways including toll-like receptor (TLR), protein kinase C (PKC), reactive oxygen species (ROS), NOD-like receptors (NLRs), and endoplasmic reticulum (ER) stress. These findings suggest that SFAs act as an important link between obesity and inflammation.

Toxicity of polycyclic aromatic hydrocarbons involves NOX2 activation

•

PAHs cause decrease in cell viability and increase in lactate levels.

•

The mixture of PAHs suppress S phase.

•

Toxicity is accompanied by NOX2 activation.

Polycyclic Aromatic Hydrocarbons (PAHs) are environmental pollutants.

The present study compares the toxic effects of BaP alone and a mixture of PAHs on human breast cancer cells. We hypothesize that PAH mixture is more toxic than BaP alone, and an increased NOX2 activation is related to PAH-induced oxidative stress. Initially, we exposed cultured human breast cancer cells to BaP alone (125 ng/mL and 500 ng/mL) and a mixture of PAHs (125 ng/mL and 500 ng/mL). After 24 h of exposure, the PAH mixture demonstrated a significant (P < 0.05) reduction in cell viability. The higher concentration of BaP alone (500 ng/mL) and both 125 ng/mL and 500 ng/mL PAH mixture significantly (P < 0.05) increased lactate production by MDA-MB-231 cells. We had observed an identical level of increased lactate levels when the cells were exposed to PAHs for 48 h. Flow cytometric analysis revealed that only PAHs mixture (both 125 ng/mL and 500 ng/mL) suppressed S phase significantly (P < 0.05). Finally, immunofluorescence microscopy was undertaken to examine the role of NOX2 due to PAHs toxicity. Colocalization of GP91phox and P47phox, a hallmark of NOX2 activation in the cell membrane of macrophage Kupffer cells demonstrated that higher concentration of BaP or PAH mixture showed increased colocalization events. These data suggest that the mixture of PAHs is more toxic and perturbing to DNA synthesis than BaP alone in cultured cells, and the toxicity is accompanied by NOX2 activation. Thus PAHs can lead to the increased burden of oxidative stress and alter the cellular redox status.

Dysbiosis-Associated Enteric Glial Cell Immune-Activation and Redox Imbalance Modulate Tight Junction Protein Expression in Gulf War Illness Pathology

About 14% of veterans who suffer from Gulf war illness (GWI) complain of some form of gastrointestinal disorder but with no significant markers of clinical pathology. Our previous studies have shown that exposure to GW chemicals resulted in altered microbiome which was associated with damage associated molecular pattern (DAMP) release followed by neuro and gastrointestinal inflammation with loss of gut barrier integrity. Enteric glial cells (EGC) are emerging as important regulators of the gastrointestinal tract and have been observed to change to a reactive phenotype in several functional gastrointestinal disorders such as IBS and IBD. This study is aimed at investigating the role of dysbiosis associated EGC immune-activation and redox instability in contributing to observed gastrointestinal barrier integrity loss in GWI via altered tight junction protein expression. Using a mouse model of GWI and in vitro studies with cultured EGC and use of antibiotics to ensure gut decontamination we show that exposure to GW chemicals caused dysbiosis associated change in EGCs. EGCs changed to a reactive phenotype characterized by activation of TLR4-S100β/RAGE-iNOS pathway causing release of nitric oxide and activation of NOX2 since gut sterility with antibiotics prevented this change. The resulting peroxynitrite generation led to increased oxidative stress that triggered inflammation as shown by increased NLRP-3 inflammasome activation and increased cell death. Activated EGCs in vivo and in vitro were associated with decrease in tight junction protein occludin and selective water channel aquaporin-3 with a concomitant increase in Claudin-2. The tight junction protein levels were restored following a parallel treatment of GWI mice with a TLR4 inhibitor SsnB and butyric acid that are known to decrease the immunoactivation of EGCs. Our study demonstrates that immune-redox mechanisms in EGC are important players in the pathology in GWI and may be possible therapeutic targets for improving outcomes in GWI symptom persistence.

Xian-Ling-Gu-Bao induced inflammatory stress rat liver injury: Inflammatory and oxidative stress playing important roles

ETHNOPHARMACOLOGICAL RELEVANCE

Xian-Ling-Gu-Bao (XLGB) Fufang is an herbal formula that has been used in clinical settings to treat osteoporosis, osteoarthritis, aseptic bone necrosis, and climacteric syndrome. Despite its uses, XLGB treatment has been linked to potential liver injury. To date, there is a lack of clear demonstration of such toxicity in animal models.

AIM OF THE STUDY

As animal models fail to reproduce the XLGB hepatotoxicity reported in humans, because human hepatocytes are clearly more sensitive to XLGB, this study was designed to investigate a more reliable animal model of such toxicity.

MATERIALS AND METHODS

We randomized rats into five groups, as follows: CON (control), XLGB, lipopolysaccharide (LPS), L-XLGB/LPS (XLGB, 0.125 g/kg; LPS, 0.1 mg/kg), and XLGB/LPS (XLGB, 1.25 g/kg; LPS, 0.1 mg/kg). These groups were treated with 0.5% sodium carboxymethyl cellulose (CMC-Na), XLGB suspension, normal saline, or LPS. The first administration of XLGB [0.125 g/kg or 1.25 g/kg, by mouth (PO)] or its solvent (0.5% CMC-Na) was delivered, and then food was removed. Twelve hours after the first administration of XLGB, rats received LPS [0.1 mg/kg, intravenously (IV)] or saline control. After 30 min, a second administration of XLGB (0.125 g/kg or 1.25 g/kg, PO) or solvent was administered. The rats were anesthetized at 12 h or 24 h following the second administration of XLGB. Liver function was evaluated by measuring liver weight, liver microscopy, serum biochemistry and plasma microRNA-122 (miR-122). The plasma levels of 27 cytokines were measured to evaluate inflammation. Moreover, the expression of cytochrome P450 2E1 (CYP2E1), nicotinic adenine dinucleotide phosphate (NADPH) oxidase and inducible nitric oxide synthase (iNOS) at protein levels were observed; immunofluorescence and immunohistochemistry were used to confirmed the hepatotoxicity of XLGB.

RESULTS

Hepatotoxicity in male rats with moderate inflammation induced by XLGB was indicated by liver histopathology, serum biochemical analysis, serum miR-122 levels, and immunofluorescent assessments. We observed significant increases in liver weight and liver indexes in male rats with moderate inflammation in response to XLGB. Histopathological assessment further showed that extensive hepatocellular necrosis and inflammatory infiltration were evident in rats co-treated with XLGB/LPS. The levels of serum transaminases [alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT)], total bilirubin (TBIL) and triglyceride (TG), which are markers of liver function, were also significantly increased by XLGB/LPS treatment. Similarly, miR-122 was significantly elevated in XLGB/LPS treated rats relative to other groups. An immunofluorescent assessment showed extensive apoptosis in hepatocytes from these co-treated rats. What is more, XLGB can dose-dependently induce liver injury in male rats with moderate inflammation. Hepatic CYP2E1, neutrophil chemotactic factor (NCF-1), iNOS, and NOX-2 (an NADPH oxidase subunit) levels were increased in response to XLGB treatment, and staining for DMPO nitrone adducts further showed elevated oxidative stress level in XLGB/LPS-treated rats relative to the other experimental groups.

CONCLUSION

LPS and XLGB co-treatment in rats led to marked hepatotoxicity. This toxicity was associated with disrupted lipid metabolism, extensive liver necrosis and inflammatory infiltration, apoptosis, and expression of oxidative stress-related proteins. These results demonstrate a valuable model for the study of iDILI in the context of XLGB treatment, and further provide insights into the potential mechanisms by which XLGB may induce hepatotoxicity in humans.

Environmental microcystin targets the microbiome and increases the risk of intestinal inflammatory pathology via NOX2 in underlying murine model of Nonalcoholic Fatty Liver Disease

With increased climate change pressures likely to influence harmful algal blooms, exposure to microcystin, a known hepatotoxin and a byproduct of cyanobacterial blooms can be a risk factor for NAFLD associated comorbidities. Using both in vivo and in vitro experiments we show that microcystin exposure in NAFLD mice cause rapid alteration of gut microbiome, rise in bacterial genus known for mediating gut inflammation and lactate production. Changes in the microbiome were strongly associated with inflammatory pathology in the intestine, gut leaching, tight junction protein alterations and increased oxidative tyrosyl radicals. Increased lactate producing bacteria from the altered microbiome was associated with increased NOX-2, an NADPH oxidase isoform. Activationof NOX2 caused inflammasome activation as shown by NLRP3/ASCII and NLRP3/Casp-1 colocalizations in these cells while use of mice lacking a crucial NOX2 component attenuated inflammatory pathology and redox changes. Mechanistically, NOX2 mediated peroxynitrite species were primary to inflammasome activation and release of inflammatory mediators. Thus, in conclusion, microcystin exposure in NAFLD could significantly alter intestinal pathology especially by the effects on microbiome and resultant redox status thus advancing our understanding of the co-existence of NAFLD-linked inflammatory bowel disease phenotypes in the clinic.

Redox Regulation of Metabolic Syndrome: Recent Developments in Skeletal Muscle Insulin Resistance and Non-alcoholic Fatty Liver Disease (NAFLD)

Several new discoveries over the past decade have shown that metabolic syndrome, a cluster of metabolic disorders, including increased visceral obesity, hyperglycemia, hypertension, dyslipidemia and low HDL-cholesterol, is commonly associated with skeletal muscle insulin resistance. More recently, non-alcoholic fatty liver disease (NAFLD) was recognized as an additional condition that is strongly associated with features of metabolic syndrome. While the pathogenesis of skeletal muscle insulin resistance and fatty liver is multifactorial, the role of dysregulated redox signaling has been clearly demonstrated in the regulation of skeletal muscle insulin resistance and NAFLD. In this review, we aim to provide recent updates on redox regulation with respect to (a) pro-oxidant enzymes (e.g. NAPDH oxidase and xanthine oxidase); (b) mitochondrial dysfunction; (c) endoplasmic reticulum (ER) stress; (d) iron metabolism derangements; and (e) gut-skeletal muscle or gut-liver connection in the development of skeletal muscle insulin resistance and NAFLD. Furthermore, we discuss promising new therapeutic strategies targeting redox regulation currently under investigation for the treatment of skeletal muscle insulin resistance and NAFLD.

Sparstolonin B (SsnB) attenuates liver fibrosis via a parallel conjugate pathway involving P53-P21 axis, TGF-beta signaling and focal adhesion that is TLR4 dependent

SsnB previously showed a promising role to lessen liver inflammation observed in a mouse model of NAFLD. Since NAFLD can progress to fibrosis, studies were designed to unravel its role in attenuating NAFLD associated fibrosis. Using both in vivo and in vitro approaches, the study probed the possible mechanisms that underlined the role of SsnB in mitigating fibrosis. Mechanistically, SsnB, a TLR4 antagonist, decreased TLR4-PI3k akt signaling by upregulating PTEN protein expression. It also decreased MDM2 protein activation and increased p53 and p21 gene and protein expression. SsnB also downregulated pro-fibrogenic hedgehog signaling pathway, inhibited hepatic stellate cell proliferation and induced apoptosis in hepatic stellate cells, a mechanism that was LPS dependent. Further, SsnB decreased fibrosis by antagonizing TLR4 induced TGFβ signaling pathway. Alternatively, SsnB augmented BAMBI (a TGFβ pseudo-receptor) expression in mice liver by inhibiting TLR4 signaling pathway and thus reduced TGFβ signaling, resulting in decreased hepatic stellate cell activation and extracellular matrix deposition. In vitro experiments on human hepatic stellate cell line showed that SsnB increased gene and protein expression of BAMBI. It also decreased nuclear co-localization of phospho SMAD2/3 and SMAD4 protein and thus attenuated TGFβ signaling in vitro. We also observed a significant decrease in phosphorylation of SMAD2/3 protein, decreased STAT3 activation, alteration of focal adhesion protein and stress fiber disassembly upon SsnB administration in hepatic stellate cells which further confirmed the antagonistic effect of SsnB on TLR4-induced fibrogenesis.

Innate Immune Signaling in Nonalcoholic Fatty Liver Disease and Cardiovascular Diseases

The physiological significance of innate immune signaling lies primarily in its role in host defense against invading pathogens. It is becoming increasingly clear that innate immune signaling also modulates the development of metabolic diseases, especially nonalcoholic fatty liver disease and cardiovascular diseases, which are characterized by chronic, low-grade inflammation due to a disarrangement of innate immune signaling. Notably, recent studies indicate that in addition to regulating canonical innate immune-mediated inflammatory responses (or immune-dependent signaling-induced responses), molecules of the innate immune system regulate pathophysiological responses in multiple organs during metabolic disturbances (termed immune-independent signaling-induced responses), including the disruption of metabolic homeostasis, tissue repair, and cell survival. In addition, emerging evidence from the study of immunometabolism indicates that the systemic metabolic status may have profound effects on cellular immune function and phenotypes through the alteration of cell-intrinsic metabolism. We summarize how the innate immune system interacts with metabolic disturbances to trigger immune-dependent and immune-independent pathogenesis in the context of nonalcoholic fatty liver disease, as representative of metabolic diseases, and cardiovascular diseases.

Triggering and resolution of inflammation in NASH

Nonalcoholic steatohepatitis (NASH) is considered the progressive form of nonalcoholic fatty liver disease (NAFLD) and is characterized by liver steatosis, inflammation, hepatocellular injury and different degrees of fibrosis. A central issue in this field relates to the identification of those factors that trigger inflammation, thus fuelling the transition from nonalcoholic fatty liver to NASH. These triggers of liver inflammation might have their origins outside the liver (such as in adipose tissue or the gut) as well as inside the organ (for instance, lipotoxicity, innate immune responses, cell death pathways, mitochondrial dysfunction and endoplasmic reticulum stress), both of which contribute to NASH development. In this Review, we summarize the currently available information on the key upstream triggers of inflammation in NASH. We further delineate the mechanisms by which liver inflammation is resolved and the implications of a defective pro-resolution process. A better knowledge of these mechanisms should help to design targeted therapies able to halt or reverse disease progression.

Membrane Remodeling as a Key Player of the Hepatotoxicity Induced by Co-Exposure to Benzo[a]pyrene and Ethanol of Obese Zebrafish Larvae

The rise in prevalence of non-alcoholic fatty liver disease (NAFLD) constitutes an important public health concern worldwide. Including obesity, numerous risk factors of NAFLD such as benzo[a]pyrene (B[a]P) and ethanol have been identified as modifying the physicochemical properties of the plasma membrane in vitro thus causing membrane remodeling—changes in membrane fluidity and lipid-raft characteristics. In this study, the possible involvement of membrane remodeling in the in vivo progression of steatosis to a steatohepatitis-like state upon co-exposure to B[a]P and ethanol was tested in obese zebrafish larvae. Larvae bearing steatosis as the result of a high-fat diet were exposed to ethanol and/or B[a]P for seven days at low concentrations coherent with human exposure in order to elicit hepatotoxicity. In this condition, the toxicant co-exposure raised global membrane order with higher lipid-raft clustering in the plasma membrane of liver cells, as evaluated by staining with the fluoroprobe di-4-ANEPPDHQ. Involvement of this membrane’s remodeling was finally explored by using the lipid-raft disruptor pravastatin that counteracted the effects of toxicant co-exposure both on membrane remodeling and toxicity. Overall, it can be concluded that B[a]P/ethanol co-exposure can induce in vivo hepatotoxicity via membrane remodeling which could be considered as a good target mechanism for developing combination therapy to deal with steatohepatitis.

High circulatory leptin mediated NOX-2-peroxynitrite-miR21 axis activate mesangial cells and promotes renal inflammatory pathology in nonalcoholic fatty liver disease

High circulatory insulin and leptin followed by underlying inflammation are often ascribed to the ectopic manifestations in non-alcoholic fatty liver disease (NAFLD) but the exact molecular pathways remain unclear. We have shown previously that CYP2E1-mediated oxidative stress and circulating leptin in NAFLD is associated with renal disease severity. Extending the studies, we hypothesized that high circulatory leptin in NAFLD causes renal mesangial cell activation and tubular inflammation via a NOX2 dependent pathway that upregulates proinflammatory miR21. High-fat diet (60% kcal) was used to induce fatty liver phenotype with parallel insulin and leptin resistance. The kidneys were probed for mesangial cell activation and tubular inflammation that showed accelerated NASH phenotype and oxidative stress in the liver. Results showed that NAFLD kidneys had significant increases in α-SMA, a marker of mesangial cell activation, miR21 levels, tyrosine nitration and renal inflammation while they were significantly decreased in leptin and p47 phox knockout mice. Micro RNA21 knockout mice showed decreased tubular immunotoxicity and proinflammatory mediator release. Mechanistically, use of NOX2 siRNA or apocynin,phenyl boronic acid (FBA), DMPO or miR21 antagomir inhibited leptin primed-miR21-mediated mesangial cell activation in vitro suggesting a direct role of leptin-mediated NOX-2 in miR21-mediated mesangial cell activation. Finally, JAK-STAT inhibitor completely abrogated the mesangial cell activation in leptin-primed cells suggesting that leptin signaling in the mesangial cells depended on the JAK-STAT pathway. Taken together the study reports a novel mechanistic pathway of leptin-mediated renal inflammation that is dependent on NOX-2-miR21 axis in ectopic manifestations underlying NAFLD-induced co-morbidities.

TLR4 promotes the expression of HIF-1α by triggering reactive oxygen species in cervical cancer cells in vitro-implications for therapeutic intervention

The present study investigated the mechanism underlying Toll-like receptor 4 (TLR4)-mediated stimulation of hypoxia-inducible factor-1α (HIF-1α) activity and its association with reactive oxygen species (ROS) in cervical cancer cells. SiHa cells were cultured and randomized to control, lipopolysaccharide (LPS), methyl-β-cyclodextrin (MβCD)+LPS, ammonium pyrrolidinedithiocarbamate (PDTC)+LPS, ST2825+LPS and small interfering (si) RNA TLR4+LPS treatment groups. Cell proliferation was quantified using an MTT assay, cell cloning was performed using soft agar colony formation and HIF-1α expression was detected by immunocytochemical staining and western blot analyses. Dichloro-dihydro-fluorescein diacetate and lucigenin luminescence assays were used to detect alterations in ROS and nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase content, respectively. Co-localization of TLR4 and HIF-1α was detected by immunofluorescence staining and observed using fluorescence microscopy. Compared with the control group, cell proliferation was enhanced in the LPS-treated group and was not altered in the PDTC+LPS treatment group. Cell proliferation was reduced in all other treatment groups (P<0.05). Compared with the LPS group, cell proliferation decreased in all other groups. Compared with the PDTC+LPS treatment group, cell proliferation significantly decreased when LPS was co-administered with ST2825, siTLR4 and MβCD (P<0.01). Treatment with MβCD+LPS exhibited an increased inhibitory effect on cell activity and proliferation. Compared with the control group, HIF-1α expression was enhanced following treatment with LPS, although it decreased when LPS was co-administered with ST2825, siTLR4 and MβCD (P<0.05). HIF-1α expression decreased following treatment with ST2825, siTLR4, MβCD and PDTC+LPS, compared with treatment with LPS alone. Compared with the PDTC+LPS group, HIF-1α activity decreased when LPS was co-administered with ST2825, siTLR4 and MβCD. NADPH oxidase and ROS levels increased in cells treated with LPS, compared with the control group, at 24 and 12 h following treatment, respectively, and decreased at 12 h when LPS was co-administered with ST2825, siTLR4 and MβCD. There was no difference between the LPS and PDTC+LPS groups with respect to NADPH and ROS levels. Compared with the PDTC+LPS group, NADPH oxidase activity and ROS content decreased when LPS was co-administered with ST2825, siTLR4 and MβCD. NADPH oxidase activity and ROS content were lowest in the MβCD+LPS treatment group, and immunofluorescent staining demonstrated that TLR4 was localized to the cell surface and HIF-1α was primarily localized to the cytoplasm. TLR4 was co-expressed with HIF-1α in cervical cancer cells. The results of the present study suggested that TLR4 signaling primarily promoted HIF-1α activity via activation of lipid rafts/NADPH oxidase redox signaling and may be associated with the initiation and progression of cervical cancer. This promoting effect was stronger in TLR4/lipid rafts/NADPH oxidase pathway than that in TLR4-NF-κB signaling pathway. Therefore, the TLR4/lipid raft-associated redox signal may be a target for therapeutic intervention to prevent the growth of cervical cancer.

HMGB1-RAGE pathway drives peroxynitrite signaling-induced IBD-like inflammation in murine nonalcoholic fatty liver disease

Recent clinical studies found a strong association of colonic inflammation and Inflammatory bowel disease (IBD)-like phenotype with NonAlcoholic Fatty liver Disease (NAFLD) yet the mechanisms remain unknown. The present study identifies high mobility group box 1 (HMGB1) as a key mediator of intestinal inflammation in NAFLD and outlines a detailed redox signaling mechanism for such a pathway. NAFLD mice showed liver damage and release of elevated HMGB1 in systemic circulation and increased intestinal tyrosine nitration that was dependent on NADPH oxidase. Intestines from NAFLD mice showed higher Toll like receptor 4 (TLR4) activation and proinflammatory cytokine release, an outcome strongly dependent on the existence of NAFLD pathology and NADPH oxidase. Mechanistically intestinal epithelial cells showed the HMGB1 activation of TLR-4 was both NADPH oxidase and peroxynitrite dependent with the latter being formed by the activation of NADPH oxidase. Proinflammatory cytokine production was significantly blocked by the specific peroxynitrite scavenger phenyl boronic acid (FBA), AKT inhibition and NADPH oxidase inhibitor Apocynin suggesting NADPH oxidase-dependent peroxynitrite is a key mediator in TLR-4 activation and cytokine release via an AKT dependent pathway. Studies to ascertain the mechanism of HMGB1-mediated NADPH oxidase activation showed a distinct role of Receptor for advanced glycation end products (RAGE) as the use of inhibitors targeted against RAGE or use of deformed HMGB1 protein prevented NADPH oxidase activation, peroxynitrite formation, TLR4 activation and finally cytokine release. Thus, in conclusion the present study identifies a novel role of HMGB1 mediated inflammatory pathway that is RAGE and redox signaling dependent and helps promote ectopic intestinal inflammation in NAFLD.

Green tea extract treatment reduces NFκB activation in mice with diet-induced nonalcoholic steatohepatitis by lowering TNFR1 and TLR4 expression and ligand availability

NFκB-mediated inflammation contributes to liver injury during nonalcoholic steatohepatitis (NASH). We hypothesized that antiinflammatory activities of green tea extract (GTE) during NASH would lower tumor necrosis factor receptor-1 (TNFR1)- and Toll-like receptor-4 (TLR4)-mediated NFκB activation. Male C57BL6/J mice (6 weeks old) were fed a low-fat (LF) or high-fat (HF) diet for 12 weeks to induce NASH. They were then randomized to continue on these diets supplemented with 0 or 2% GTE (n=10/group) for an additional 8 weeks prior to evaluating NASH, NFκB inflammation and TNFR1 and TLR4 receptor complexes and their respective ligands, TNFα and endotoxin. HF feeding increased (P<.05) serum alanine aminotransferase (ALT) activity and histological evidence of NASH compared with LF controls. HF-mediated increases in NFκB p65 phosphorylation were also accompanied by increased serum TNFα and endotoxin concentrations, mRNA expression of hepatic TNFR1 and TLR4 and MyD88 protein levels. GTE in LF mice had no effect (P>.05) on liver histology or inflammatory responses. However, GTE in HF mice decreased biochemical and histological parameters of NASH and lowered hepatic p65 phosphorylation in association with decreased serum TNFα, mRNA expression of TNFR1 and TLR4 and MyD88 protein. GTE in HF-fed mice also lowered serum endotoxin and up-regulated mRNA expression of duodenal occludin and zonula occluden-1 and ileal occludin and claudin-1 that were otherwise lowered in expression by HF feeding. These data suggest that dietary GTE treatment reduces hepatic inflammation in NASH by decreasing proinflammatory signaling through TNFR1 and TLR4 that otherwise increases NFκB activation and liver injury.

Zebrafish larva as a reliable model for in vivo assessment of membrane remodeling involvement in the hepatotoxicity of chemical agents

The easy-to-use in vivo model, zebrafish larva, is being increasingly used to screen chemical-induced hepatotoxicity, with a good predictivity for various mechanisms of liver injury. However, nothing is known about its applicability in exploring the mechanism called membrane remodeling, depicted as changes in membrane fluidity or lipid raft properties. The aim of this study was, therefore, to substantiate the zebrafish larva as a suitable in vivo model in this context. Ethanol was chosen as a prototype toxicant because it is largely described, both in hepatocyte cultures and in rodents, as capable of inducing a membrane remodeling leading to hepatocyte death and liver injury. The zebrafish larva model was demonstrated to be fully relevant as membrane remodeling was maintained even after a 1-week exposure without any adaptation as usually reported in rodents and hepatocyte cultures. It was also proven to exhibit a high sensitivity as it discriminated various levels of cytotoxicity depending on the extent of changes in membrane remodeling. In this context, its sensitivity appeared higher than that of WIF-B9 hepatic cells, which is suited for analyzing this kind of hepatotoxicity. Finally, the protection afforded by a membrane stabilizer, ursodeoxycholic acid (UDCA), or by a lipid raft disrupter, pravastatin, definitely validated zebrafish larva as a reliable model to quickly assess membrane remodeling involvement in chemical-induced hepatotoxicity. In conclusion, this model, compatible with a high throughput screening, might be adapted to seek hepatotoxicants via membrane remodeling, and also drugs targeting membrane features to propose new preventive or therapeutic strategies in chemical-induced liver diseases. Copyright © 2016 John Wiley & Sons, Ltd.

Studies on DNA interaction of organotin(IV) complexes of meso-tetra(4-sulfonatophenyl)porphine that show cellular activity

The interaction of the diorgano- and triorganotin(IV) derivatives of meso-tetra-(4-sulfonatophenyl)porphine (Me₂Sn)₂TPPS, (Bu₂Sn)₂TPPS, (Me₃Sn)₄TPPS and (Bu₃Sn)₄TPPS to natural DNA was analysed (together with free meso-tetra-(4-sulfonatophenyl)porphine (TPPS^4-) for comparison purposes). Particular attention was paid to (Bu₃Sn)₄TPPS, a species that shows significant cellular action. Preliminary tests were done on the solution properties of the organotin(IV) compounds (pK_A and possible self-aggregation). Spectrophotometric and spectrofluorometric experiments showed that all the investigated organotin(IV) derivatives strongly interact with DNA, the binding energy depending on the dye steric hindrance. In all cases experimental data concur in indicating that external binding mode prevails. Interestingly, fluorescence quenching and viscosity experiments show that the Bu-containing species, and in particular (Bu₃Sn)₄TPPS, are able to noticeably alter the DNA conformation.

EXPRESS: Methylcobalamin ameliorates neuropathic pain induced by vincristine in rats: Effect on loss of peripheral nerve fibers and imbalance of cytokines in the spinal dorsal horn

Background

Vincristine, a widely used chemotherapeutic agent, often induces painful peripheral neuropathy and there are currently no effective drugs to prevent or treat this side effect. Previous studies have shown that methylcobalamin has potential analgesic effect in diabetic and chronic compression of dorsal root ganglion model; however, whether methylcobalamin has effect on vincristine-induced painful peripheral neuropathy is still unknown.

Results

We found that vincristine-induced mechanical allodynia and thermal hyperalgesia, accompanied by a significant loss of intraepidermal nerve fibers in the plantar hind paw skin and an increase in the incidence of atypical mitochondria in the sciatic nerve. Moreover, in the spinal dorsal horn, the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and the protein expression of p-p65 as well as tumor necrosis factor α was increased, whereas the protein expression of IL-10 was decreased following vincristine treatment. Furthermore, intraperitoneal injection of methylcobalamin could dose dependently attenuate vincristine-induced mechanical allodynia and thermal hyperalgesia, which was associated with intraepidermal nerve fibers rescue, and atypical mitochondria prevalence decrease in the sciatic nerve. Moreover, methylcobalamin inhibited the activation of NADPH oxidase and the downstream NF-κB pathway. Production of tumor necrosis factor α was also decreased and production of IL-10 was increased in the spinal dorsal horn following methylcobalamin treatment. Intrathecal injection of Phorbol-12-Myristate-13-Acetate, a NADPH oxidase activator, could completely block the analgesic effect of methylcobalamin.

Conclusions

Methylcobalamin attenuated vincrinstine-induced neuropathic pain, which was accompanied by inhibition of intraepidermal nerve fibers loss and mitochondria impairment. Inhibiting the activation of NADPH oxidase and the downstream NF-κB pathway, resulting in the rebalancing of proinflammatory and anti-inflammatory cytokines in the spinal dorsal horn might also be involved. These findings might provide potential target for preventing vincristine-induced neuropathic pain.

Sparstolonin B attenuates early liver inflammation in experimental NASH by modulating TLR4 trafficking in lipid rafts via NADPH oxidase activation

Although significant research data exist on the pathophysiology of nonalcoholic steatohepatitis (NASH), finding an efficient treatment regimen for it remains elusive. The present study used sparstolonin B (SsnB), a novel TLR4 antagonist derived from the Chinese herb Sparganium stoloniferum, as a possible drug to mitigate early inflammation in NASH. This study used an early steatohepatitic injury model in high-fat-fed mice with CYP2E1-mediated oxidative stress as a second hit. SsnB was administered for 1 wk along with bromodichloromethane (BDCM), an inducer of CYP2E1-mediated oxidative stress. Results showed that SsnB administration attenuated inflammatory morphology and decreased elevation of the liver enzyme alanine aminotransferase (ALT). Mice administered SsnB also showed decreased mRNA expression of proinflammatory cytokines TNF-α, IFN-γ, IL-1β, and IL-23, while protein levels of both TNF-α and IL-1β were significantly decreased. SsnB significantly decreased Kupffer cell activation as evidenced by reduction in CD68 and monocyte chemoattractant protein-1 (MCP1) mRNA and protein levels with concomitant inhibition of macrophage infiltration in the injured liver. Mechanistically, SsnB decreased TLR4 trafficking to the lipid rafts, a phenomenon described by the colocalization of TLR4 and lipid raft marker flotillin in tissues and immortalized Kupffer cells. Since we have shown previously that NADPH oxidase drives TLR4 trafficking in NASH, we studied the role of SsnB in modulating this pathway. SsnB prevented NADPH oxidase activation in vivo and in vitro as indicated by decreased peroxynitrite formation. In summary, the present study reports a novel use of the TLR4 antagonist SsnB in mitigating inflammation in NASH and in parallel shows a unique molecular mechanism of decreasing nitrative stress.

Deletion of P2X7 attenuates hyperoxia-induced acute lung injury via inflammasome suppression

Increasing evidence shows that hyperoxia is a serious complication of oxygen therapy in acutely ill patients that causes excessive production of free radicals leading to hyperoxia-induced acute lung injury (HALI). Our previous studies have shown that P2X7 receptor activation is required for inflammasome activation during HALI. However, the role of P2X7 in HALI is unclear. The main aim of this study was to determine the effect of P2X7 receptor gene deletion on HALI. Wild-type (WT) and P2X7 knockout (P2X7 KO) mice were exposed to 100% O2 for 72 h. P2X7 KO mice treated with hyperoxia had enhanced survival in 100% O2 compared with the WT mice. Hyperoxia-induced recruitment of inflammatory cells and elevation of IL-1β, TNF-α, monocyte chemoattractant protein-1, and IL-6 levels were attenuated in P2X7 KO mice. P2X7 deletion decreased lung edema and alveolar protein content, which are associated with enhanced alveolar fluid clearance. In addition, activation of the inflammasome was suppressed in P2X7-deficient alveolar macrophages and was associated with suppression of IL-1β release. Furthermore, P2X7-deficient alveolar macrophage in type II alveolar epithelial cells (AECs) coculture model abolished protein permeability across mouse type II AEC monolayers. Deletion of P2X7 does not lead to a decrease in epithelial sodium channel expression in cocultures of alveolar macrophages and type II AECs. Taken together, these findings show that deletion of P2X7 is a protective factor and therapeutic target for the amelioration of hyperoxia-induced lung injury.