Transient receptor potential vanilloid 1 interacts with TLR4/CD14 signaling pathway in lipopolysaccharide-mediated inflammation in macrophages.

Transient receptor potential vanilloid 1 (TRPV1), a ligand-gated cation channel, is a receptor for vanilloids on sensory neurons and is also activated by capsaicin, heat, protons, arachidonic acid metabolites, and inflammatory mediators on neuronal or non-neuronal cells. However, the role of the TRPV1 receptor in pro-inflammatory cytokine secretion and its potential regulatory mechanisms in lipopolysaccharide (LPS)-induced inflammation has yet to be entirely understood. To investigate the role and regulatory mechanism of the TRPV1 receptor in regulating LPS-induced inflammatory responses, bone marrow-derived macrophages (BMDMs) harvested from wild-type (WT) and TRPV1 deficient (Trpv1-/-) mice were used as the cell model. In WT BMDMs, LPS induced an increase in the levels of tumor necrosis factor-α, interleukin-1ß, inducible nitric oxide synthase (iNOS), and nitric oxide, which were attenuated in Trpv1-/- BMDMs. Additionally, the phosphorylation of IκBα and mitogen-activated protein kinases, as well as the translocation of NF-κB and AP-1, were all decreased in LPS-treated Trpv1-/- BMDMs. Immunoprecipitation assay revealed that LPS treatment increased the formation of TRPV1-TLR4-CD14 complex in WT BMDMs. Genetic deletion of TRPV1 in BMDMs impaired the LPS-triggered immune-complex formation of TLR4, MyD88, and IRAK, all of which are essential regulators in LPS-induced activation of the TLR4 signaling pathway. Moreover, genetic deletion of TRPV1 prevented the LPS-induced lethality and pro-inflammatory production in mice. In conclusion, the TRPV1 receptor may positively regulate the LPS-mediated inflammatory responses in macrophages by increasing the interaction with the TLR4-CD14 complex and activating the downstream signaling cascade.

Apigenin targets fetuin-A to ameliorate obesity-induced insulin resistance.

Fetuin-A, a hepatokine secreted by hepatocytes, binds to insulin receptors and consequently impairs the activation of the insulin signaling pathway, leading to insulin resistance. Apigenin, a flavonoid isolated from plants, has beneficial effects on insulin resistance; however, its regulatory mechanisms are not fully understood. In the present study, we investigated the molecular mechanisms underlying the protective effects of apigenin on insulin resistance. In Huh7 cells, treatment with apigenin decreased the mRNA expression of fetuin-A by decreasing reactive oxygen species-mediated casein kinase 2α (CK2α)-nuclear factor kappa-light-chain-enhancer of activated B activation; besides, apigenin decreased the levels of CK2α-dependent fetuin-A phosphorylation and thus promoted fetuin-A degradation through the autophagic pathway, resulting in a decrease in the protein levels of fetuin-A. Moreover, apigenin prevented the formation of the fetuin-A-insulin receptor (IR) complex and thereby rescued the PA-induced impairment of the insulin signaling pathway, as evidenced by increased phosphorylation of IR substrate-1 and Akt, and translocation of glucose transporter 2 from the cytosol to the plasma membrane. Similar results were observed in the liver of HFD-fed mice treated with apigenin. Collectively, our findings revealed that apigenin ameliorates obesity-induced insulin resistance in the liver by targeting fetuin-A.

Selective brain perfusion improves the neurological outcomes after extracorporeal cardiopulmonary resuscitation in a rat model.

BACKGROUND: The major concern in patients who have suffered from cardiac arrest (CA) and undergone successful extracorporeal cardiopulmonary resuscitation (E-CPR) is poor neurological outcomes. In this study, we aimed to introduce a rat model of selective brain perfusion (SBP) during E-CPR to improve the neurological outcome after CA. METHODS: The rats underwent 7 min of untreated asphyxial CA and then were resuscitated with E-CPR for 30 min. The right external jugular vein and right femoral artery were separately cannulated to the E-CPR outflow and inflow. The right common carotid artery was cannulated from the proximal to the distal side for SBP. Subsequently, rats were removed from E-CPR, wounds were closed, and 90 min of intensive care were provided. Neurological deficit scores were tested after 4 h of recovery when the rats were mechanical ventilation-free. S100 calcium-binding protein B (S100B) and glial fibrillary acidic protein (GFAP) were detected through immunohistochemistry (IHC) of brain tissue. RESULTS: The rats that received SBP while resuscitated by E-CPR showed markedly better neurological performances after 4-h recovery than those resuscitated by E-CPR only. The IHC staining of GFAP and S100B in the hippocampus was low in the rats receiving SBP during E-CPR, but only GFAP showed significant differences. CONCLUSIONS: We successfully developed a novel and reproducible rat model of SBP while resuscitated by E-CPR to ameliorate the neurological performances after CA. This achievement might have opportunities for studying how to improve the neurological outcome in the clinical condition.

Advances in the molecular mechanisms of statins in regulating endothelial nitric oxide bioavailability: Interlocking biology between eNOS activity and L-arginine metabolism.

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A, are widely used to treat hypercholesterolemia. In addition, statins have been suggested to reduce the risk of cardiovascular events owing to their pleiotropic effects on the vascular system, including vasodilation, anti-inflammation, anti-coagulation, anti-oxidation, and inhibition of vascular smooth muscle cell proliferation. The major beneficial effect of statins in maintaining vascular homeostasis is the induction of nitric oxide (NO) bioavailability by activating endothelial NO synthase (eNOS) in endothelial cells. The mechanisms underlying the increased NO bioavailability and eNOS activation by statins have been well-established in various fields, including transcriptional and post-transcriptional regulation, kinase-dependent phosphorylation and protein-protein interactions. However, the mechanism by which statins affect the metabolism of L-arginine, a precursor of NO biosynthesis, has rarely been discussed. Autophagy, which is crucial for energy homeostasis, regulates endothelial functions, including NO production and angiogenesis, and is a potential therapeutic target for cardiovascular diseases. In this review, in addition to summarizing the molecular mechanisms underlying increased NO bioavailability and eNOS activation by statins, we also discuss the effects of statins on the metabolism of L-arginine.

Association of mono-2-ethylhexyl phthalate with adverse outcomes in chronic hemodialysis patients.

Phthalate exposure is widespread and has a global impact. Growing evidence shows that mono-2-ethylhexyl phthalate (MEHP) exposure has a negative impact on human health. However, whether MEHP exposure is associated with mortality and other adverse outcomes in hemodialysis patients remains unknown. This study prospectively enrolled 217 patients on maintenance hemodialysis from June 30, 2021, to August 16, 2022. Baseline serum MEHP, di-2-ethylhexyl phthalate (DEHP), and indoxyl sulfate (IS) concentrations were measured. Primary endpoints were all-cause mortality or composite adverse outcomes, including all-cause death plus hospitalization due to cardiovascular disease, heart failure, stroke, infection, or cancer. Serum MEHP concentrations were positively associated with DEHP but not indoxyl sulfate concentrations in hemodialysis patients. Additionally, serum MEHP concentrations were significantly and independently associated with all-cause mortality and composite adverse outcomes (adjusted hazard ratios [HRs], 1.04 and 1.03 per ng/mL, 95% confidence intervals [CIs], 1.01-1.07 and 1.00-1.05; p = 0.016 and 0.015, respectively). We found a cutoff value of MEHP for predicting both endpoints. Patients with serum MEHP concentrations of ≥ 41.8 ng/mL had much higher risks for all-cause mortality and composite adverse outcomes (adjusted HRs, 39.2 and 13; 95% CIs, 2.44-65.7 and 2.74-61.4; p = 0.011 and 0.001, respectively). MEHP exposure is significantly associated with higher risks for all-cause mortality and composite adverse outcomes. Hemodialysis patients with serum MEHP concentrations above 41.8 ng/mL had much poorer prognoses regarding both outcomes.

Folic Acid Ameliorates Renal Injury in Experimental Obstructive Nephropathy: Role of Glycine N-Methyltransferase.

Folic acid exerts both anti-inflammatory and antifibrotic effects. Glycine N-methyltransferase (GNMT), the major folic acid-binding protein in the liver, is a crucial enzyme that regulates the cellular methylation process by maintaining S-adenosylmethionine levels. However, as yet neither the therapeutic effects of folic acid in renal fibrosis nor whether GNMT is involved in these folic acid-associated mechanisms has been investigated. First, the expression of GNMT was examined in human kidneys with or without obstructive nephropathy. Later, wild-type and GNMT knockout (GNMT-/-) mice were subjected to unilateral ureteral obstruction (UUO) and then treated with either folic acid or vehicle for 14 days. Renal tubular injury, inflammation, fibrosis, and autophagy were evaluated by histological analysis and Western blotting. We observed increased expression of GNMT in humans with obstructive nephropathy. Furthermore, UUO significantly increased the expression of GNMT in mice; in addition, it caused renal injury as well as the development of both hydronephrosis and tubular injury. These were all alleviated by folic acid treatment. In contrast, GNMT-/- mice exhibited exacerbated UUO-induced renal injury, but the protective effect of folic acid was not observed in GNMT-/- mice. We propose a novel role for folic acid in the treatment of renal fibrosis, which indicates that GNMT may be a therapeutic target.

Di-(2-ethylhexyl) Phthalate Limits the Lipid-Lowering Effects of Simvastatin by Promoting Protein Degradation of Low-Density Lipoprotein Receptor: Role of PPARγ-PCSK9 and LXRα-IDOL Signaling Pathways.

Dialysis prevents death from uremia in patients with end-stage renal disease (ESRD). Nevertheless, during hemodialysis, circulating levels of di-(2-ethylhexyl) phthalate (DEHP) are increased due to phthalates leaching from medical tubes. Statins are an effective therapy for reducing the risks associated with cardiovascular diseases in patients with chronic kidney disease; however, the mechanism by which statins fail to reduce cardiovascular events in hemodialysis ESRD patients remains unclear. In this study, we investigated whether DEHP and its metabolites interfere with the lipid-lowering effect of statins in hepatocytes. In Huh7 cells, treatment with DEHP and its metabolites abolished the simvastatin-conferred lipid-lowering effect. Mechanistically, DEHP down-regulated the expression of low-density lipoprotein receptor (LDLR) and led to a decrease in LDL binding, which was mediated by the activation of the PPARγ-PCSK9 and LXRα-IDOL signaling pathways. Additionally, the NOX-ROS-TRPA1 pathway is involved in the DEHP-mediated inhibition of LDLR expression and LDL binding activity. Blockage of this pathway abrogated the DEHP-mediated inhibition in the LDLR expression and LDL binding of simvastatin. Collectively, DEHP induces the activation of the NOX-ROS-TRPA1 pathway, which in turn activates PPARγ-PCSK9- and LXRα-IDOL-dependent signaling, and, ultimately, diminishes the statin-mediated lipid-lowering effect in hepatocytes.

Ractopamine at legal residue dosage accelerates atherosclerosis by inducing endothelial dysfunction and promoting macrophage foam cell formation.

Ractopamine, a synthetic ß-adrenoreceptor agonist, is used as an animal feed additive to increase food conversion efficiency and accelerate lean mass accretion in farmed animals. The U.S. Food and Drug Administration claimed that ingesting products containing ractopamine residues at legal dosages might not cause short-term harm to human health. However, the effect of ractopamine on chronic inflammatory diseases and atherosclerosis is unclear. Therefore, we investigated the effects of ractopamine on atherosclerosis and its action mechanism in apolipoprotein E-null (apoe-/-) mice and human endothelial cells (ECs) and macrophages. Daily treatment with ractopamine for four weeks increased the body weight and the weight of brown adipose tissues and gastrocnemius muscles. However, it decreased the weight of white adipose tissues in apoe-/- mice. Additionally, ractopamine exacerbated hyperlipidemia and systemic inflammation, deregulated aortic cholesterol metabolism and inflammation, and accelerated atherosclerosis. In ECs, ractopamine treatment induced endothelial dysfunction and increased monocyte adhesion and transmigration across ECs. In macrophages, ractopamine dysregulated cholesterol metabolism by increasing oxidized low-density lipoprotein (oxLDL) internalization and decreasing reverse cholesterol transporters, increasing oxLDL-induced lipid accumulation. Collectively, our findings revealed that ractopamine induces EC dysfunction and deregulated cholesterol metabolism of macrophages, which ultimately accelerates atherosclerosis progression.

New Mechanisms of Bromelain in Alleviating Non-Alcoholic Fatty Liver Disease-Induced Deregulation of Blood Coagulation.

Bromelain, an enzyme extracted from the stems of pineapples, exerts anticoagulant effects; however, the regulatory mechanisms are not fully understood. Here, we aimed to investigate the effects of bromelain on non-alcoholic fatty liver disease (NAFLD)-induced deregulation of blood coagulation and the underlying molecular mechanisms. C57BL/6 mice were fed a high-fat diet (HFD), with or without bromelain (20 mg/kg/day) administration, for 12 weeks. Treatment with bromelain decreased thrombus formation in the liver and prolonged HFD-induced shortened prothrombin, activated partial thromboplastin, and fibrinogen times. Moreover, liquid chromatography-mass spectrometry/mass spectrometry and Western blot analysis showed that bromelain inhibited NAFLD-induced activation of the intrinsic, extrinsic, and common pathways by upregulating the protein expression of antithrombin III, serpin family G member 1, and α1-antitrypsin, and downregulating the protein expression of fibrinogen in the liver and plasma. Bromelain also upregulated the level of plasminogen and downregulating factor XIII expression in the liver and plasma. Collectively, these findings suggest that bromelain exerts anticoagulant effects on NAFLD-induced deregulation of coagulation by inhibiting the activation of the coagulation cascade, decreasing the stability of clots, and promoting fibrinolytic activity. The present study provides new insights into the potential therapeutic value of bromelain for the prevention and treatment of thrombosis-related diseases.

Genetic Deletion of HLJ1 Does Not Affect Blood Coagulation in Mice.

HLJ1 (also called DNAJB4) is a member of the DNAJ/Hsp40 family and plays an important role in regulating protein folding and activity. However, there is little information about the role of HLJ1 in the regulation of physiological function. In this study, we investigated the role of HLJ1 in blood coagulation using wild-type C57BL/6 mice and HLJ1-null (HLJ1-/-) mice. Western blot analysis and immunohistochemistry were used to assess the expression and distribution of HLJ1 protein, respectively. The tail bleeding assay was applied to assess the bleeding time and blood loss. A coagulation test was used for measuring the activity of extrinsic, intrinsic and common coagulation pathways. Thromboelastography was used to measure the coagulation parameters in the progression of blood clot formation. The results showed that HLJ1 was detectable in plasma and bone marrow. The distribution of HLJ1 was co-localized with CD41, the marker of platelets and megakaryocytes. However, genetic deletion of HLJ1 did not alter blood loss and the activity of extrinsic and intrinsic coagulation pathways, as well as blood clot formation, compared to wild-type mice. Collectively, these findings suggest that, although HLJ1 appears in megakaryocytes and platelets, it may not play a role in the function of blood coagulation under normal physiological conditions.

Bromelain Ameliorates Atherosclerosis by Activating the TFEB-Mediated Autophagy and Antioxidant Pathways.

Bromelain, a cysteine protease found in pineapple, has beneficial effects in the treatment of inflammatory diseases; however, its effects in cardiovascular pathophysiology are not fully understood. We investigated the effect of bromelain on atherosclerosis and its regulatory mechanisms in hyperlipidemia and atheroprone apolipoprotein E-null (apoe-/-) mice. Bromelain was orally administered to 16-week-old male apoe-/- mice for four weeks. Daily bromelain administration decreased hyperlipidemia and aortic inflammation, leading to atherosclerosis retardation in apoe-/- mice. Moreover, hepatic lipid accumulation was decreased by the promotion of cholesteryl ester hydrolysis and autophagy through the AMP-activated protein kinase (AMPK)/transcription factor EB (TFEB)-mediated upregulation of autophagy- and antioxidant-related proteins. Moreover, bromelain decreased oxidative stress by increasing the antioxidant capacity and protein expression of antioxidant proteins while downregulating the protein expression of NADPH oxidases and decreasing the production of reactive oxygen species. Therefore, AMPK/TFEB signaling may be crucial in bromelain-mediated anti-hyperlipidemia, antioxidant, and anti-inflammatory effects, effecting the amelioration of atherosclerosis.

Atypical antipsychotic drugs deregulate the cholesterol metabolism of macrophage-foam cells by activating NOX-ROS-PPARγ-CD36 signaling pathway.

BACKGROUND: Clinical reports indicate that schizophrenia patients taking atypical antipsychotic drugs suffer from metabolism diseases including atherosclerosis. However, the mechanisms underlying the detrimental effect of atypical antipsychotic drugs on atherosclerosis remain to be explored. METHODS: In this study, we used apolipoprotein E-deficient (apoe-/-) hyperlipidemic mice and apoe-/-cd36-/- mice to investigate the underlying mechanism of atypical antipsychotic drugs on atherosclerosis and macrophage-foam cells. RESULTS: In vivo studies showed that genetic deletion of cd36 gene ablated the pro-atherogenic effect of olanzapine in apoe-/- mice. Moreover, in vitro studies revealed that genetic deletion or siRNA-mediated knockdown of cd36 or pharmacological inhibition of CD36 prevented atypical antipsychotic drugs-induced oxLDL accumulation in macrophages. Additionally, olanzapine and clozapine activated NADPH oxidase (NOX) to generate reactive oxygen species (ROS) which upregulated the activity of peroxisome proliferator-activated receptor γ (PPARγ) and subsequently elevated CD36 expression. Inhibition of NOX activity, ROS production or PPARγ activity suppressed CD36 expression and abolished the detrimental effects of olanzapine and clozapine on oxLDL accumulation in macrophages. CONCLUSION: Collectively, our results suggest that atypical antipsychotic drugs exacerbate atherosclerosis and macrophage-foam cell formation by activating the NOX-ROS-PPARγ-CD36 pathway.

Hyperuricemia induces endothelial dysfunction and accelerates atherosclerosis by disturbing the asymmetric dimethylarginine/dimethylarginine dimethylaminotransferase 2 pathway.

Hyperuricemia is closely associated with the mobility and mortality of patients with cardiovascular diseases. However, how hyperuricemia accelerates atherosclerosis progression is not well understood. The balance between asymmetric dimethylarginine (ADMA) and dimethylarginine dimethylaminotransferases (DDAHs) is crucial to regulate vascular homeostasis. Therefore, we investigated the role of the ADMA/DDAH pathway in hyperuricemia-induced endothelial dysfunction and atherosclerosis and the underlying molecular mechanisms in endothelial cells (ECs) and apolipoprotein E-knockout (apoe-/-) mice. Our results demonstrated that uric acid at pathological concentrations increased the intracellular levels of ADMA and downregulated DDAH-2 expression without affecting DDAH-1 expression. Excess uric acid also reduced NO bioavailability and increased monocyte adhesion to ECs, which were abolished by using the antioxidant N-acetylcysteine, the nicotinamide adenine dinucleotide phosphate oxidase inhibitor apocynin, or DDAH-2 overexpression. In apoe-/- mice, treatment with oxonic acid, a uricase inhibitor, increased the circulating level of uric acid, cholesterol, and lipid peroxidation; exacerbated systemic and aortic inflammation; and worsened atherosclerosis compared with vehicle-treated apoe-/- mice. Furthermore, oxonic acid-treated apoe-/- mice exhibited elevated ADMA plasma level and downregulated aortic expression of DDAH-2 protein. Notably, DDAH-2 overexpression in the ECs of apoe-/- mice prevented hyperuricemia-induced deleterious effects from influencing ADMA production, lipid peroxidation, inflammation, and atherosclerosis. Collectively, our findings suggest that hyperuricemia disturbs the balance of the ADMA/DDAH-2 axis, results in EC dysfunction, and, consequently, accelerates atherosclerosis.

Role of TRPA1 in Tissue Damage and Kidney Disease.

TRPA1, a nonselective cation channel, is expressed in sensory afferent that innervates peripheral targets. Neuronal TRPA1 can promote tissue repair, remove harmful stimuli and induce protective responses via the release of neuropeptides after the activation of the channel by chemical, exogenous, or endogenous irritants in the injured tissue. However, chronic inflammation after repeated noxious stimuli may result in the development of several diseases. In addition to sensory neurons, TRPA1, activated by inflammatory agents from some non-neuronal cells in the injured area or disease, might promote or protect disease progression. Therefore, TRPA1 works as a molecular sentinel of tissue damage or as an inflammation gatekeeper. Most kidney damage cases are associated with inflammation. In this review, we summarised the role of TRPA1 in neurogenic or non-neurogenic inflammation and in kidney disease, especially the non-neuronal TRPA1. In in vivo animal studies, TRPA1 prevented sepsis-induced or Ang-II-induced and ischemia-reperfusion renal injury by maintaining mitochondrial haemostasis or via the downregulation of macrophage-mediated inflammation, respectively. Renal tubular epithelial TRPA1 acts as an oxidative stress sensor to mediate hypoxia-reoxygenation injury in vitro and ischaemia-reperfusion-induced kidney injury in vivo through MAPKs/NF-kB signalling. Acute kidney injury (AKI) patients with high renal tubular TRPA1 expression had low complete renal function recovery. In renal disease, TPRA1 plays different roles in different cell types accordingly. These findings depict the important role of TRPA1 and warrant further investigation.

Renal Tubular Epithelial TRPA1 Acts as An Oxidative Stress Sensor to Mediate Ischemia-Reperfusion-Induced Kidney Injury through MAPKs/NF-κB Signaling.

Oxidative stress and inflammation play important roles in the pathophysiology of acute kidney injury (AKI). Transient receptor potential ankyrin 1 (TRPA1) is a Ca2+-permeable ion channel that is sensitive to reactive oxygen species (ROS). The role of TRPA1 in AKI remains unclear. In this study, we used human and animal studies to assess the role of renal TRPA1 in AKI and to explore the regulatory mechanism of renal TRPA1 in inflammation via in vitro experiments. TRPA1 expression increased in the renal tubular epithelia of patients with AKI. The severity of tubular injury correlated well with tubular TRPA1 or 8-hydroxy-2'-deoxyguanosine expression. In an animal model, renal ischemia-reperfusion injury (IR) increased tubular TRPA1 expression in wild-type (WT) mice. Trpa1-/- mice displayed less IR-induced tubular injury, oxidative stress, inflammation, and dysfunction in kidneys compared with WT mice. In the in vitro model, TRPA1 expression increased in renal tubular cells under hypoxia-reoxygenation injury (H/R) conditions. We demonstrated that H/R evoked a ROS-dependent TRPA1 activation, which elevated intracellular Ca2+ level, increased NADPH oxidase activity, activated MAPK/NF-κB signaling, and increased IL-8. Renal tubular TRPA1 may serve as an oxidative stress sensor and a crucial regulator in the activation of signaling pathways and promote the subsequent transcriptional regulation of IL-8. These actions might be evident in mice with IR or patients with AKI.

Apigenin ameliorates hepatic lipid accumulation by activating the autophagy-mitochondria pathway.

Apigenin, a flavonoid isolated from plants, provides protection against non-alcoholic fatty liver disease. However, the mechanism by which apigenin decreases lipid accumulation in the liver is unclear. In this study, we investigated the molecular mechanism underlying the beneficial effect of apigenin on the hepatic deregulation of lipid metabolism. Oleic acid (OA)-induced lipid accumulation in human hepatoma cells (Huh7 cells) was used as an in vitro model. Western blot analysis was used for evaluating protein expression. Oil red O staining, Nile red staining, and conventional assay kits were used to assess the level of lipids. Immunocytochemistry was performed to observe mitochondrial morphology. Seahorse XF analyzer was used to measure mitochondrial bioenergetics. Treatment with OA induced lipid accumulation in Huh7 cells, which was attenuated by apigenin. Mechanistically, treatment with apigenin increased the expression of autophagy-related proteins including Beclin1, autophagy related gene 5 (ATG5), ATG7, and LC3II, and the formation of autophagolysosomes, leading to an increase in intracellular levels of fatty acids. Inhibition of autophagy by bafilomycin A1 or chloroquine abolished the protection of apigenin in OA-induced lipid accumulation. Apigenin up-regulated the protein expression related to the ß-oxidation pathway including acyl-CoA synthetase long chain family member 1, carnitine palmitoyltransferase 1α, acyl-CoA oxidase 1, peroxisome proliferator activated receptor (PPAR) α, and PPARγ coactivator 1-α. Moreover, apigenin increased the mitochondrial network structure and mitochondrial function by increasing the protein expression related to the process of mitochondria fusion and mitochondrial function. Collectively, our findings suggest that apigenin ameliorates hepatic lipid accumulation by activating the autophagy-mitochondrial pathway.

Lung Epithelial TRPA1 Mediates Lipopolysaccharide-Induced Lung Inflammation in Bronchial Epithelial Cells and Mice.

Toll-like receptor (TLR) 4 was originally thought to be the sole pattern recognition receptor for lipopolysaccharide (LPS). Transient receptor potential ankyrin 1 (TRPA1), a Ca2+-permeant channel, has been suggested as a non-TLR receptor membrane-bound sensor of LPS. We recently reported that TRPA1 is expressed in lung epithelial cells (LECs) and mediates lung inflammation induced by cigarette smoke. However, the role of TRPA1 in LPS-induced lung inflammation has not been conclusively defined, and its underlying cellular mechanisms remain unclear. In this study, our in vitro results showed that LPS sequentially produced a cascade of events, including the elevation of intracellular Ca2+, the activation of NADPH oxidase, increase in intracellular reactive oxygen species (ROS), the activation of mitogen-activated protein kinase (MAPK)/nuclear factor-kB (NF-κB) signaling, and the induction of IL-8. The increase in intracellular Ca2+ was inhibited by HC030031 (a TRPA1 antagonist) but was unaffected by TAK-242 (a TLR-4 inhibitor). The activation of NADPH oxidase was prevented by its inhibitor apocynin, EGTA (an extracellular Ca2+ chelator), and HC030031. The increase in intracellular ROS was attenuated by apocynin, N-acetyl-cysteine (NAC, a ROS scavenger), EGTA, and HC030031. The activation of the MAPK/NF-κB signaling was halted by NAC, EGTA, and HC030031. IL-8 induction was suppressed by HC030031 and TRPA1 siRNA, and further reduced by the combination of HC030031 and TAK-242. Our in vivo studies showed that trpa1-/- mice exhibited a reduced level of LPS-induced lung inflammation compared with wild-type mice as evidenced by the alleviations of increases in vascular permeability, inflammatory cell infiltration, inflammatory cytokine levels, oxidative stress, and MAPK signaling activation. Thus, in LECs, LPS may activate TRPA1 resulting in an increase in Ca2+ influx. The increased intracellular Ca2+ leads to NADPH oxidase activation, which causes an increase in intracellular ROS. The intracellular ROS activates the MAPK/NF-κB signaling resulting in IL-8 induction. This mechanism may possibly be at work to induce lung inflammation in mice.

Di-(2-ethylhexyl) phthalate limits the pleiotropic effects of statins in chronic kidney disease patients undergoing dialysis and endothelial cells.

The level of di-(2-ethylhexyl) phthalate (DEHP) is elevated in chronic kidney disease patients undergoing dialysis. However, statins are unable to reduce the cardiovascular events in chronic dialysis patients. In this study, we investigated the effects of DEHP on statin-conferred pleiotropic effects and the underlying molecular mechanism in peritoneal dialysis (PD) patients and endothelial cells (ECs). In PD patients with serum DEHP level ≥0.0687 µg/mL, statin treatment was not associated with lower risk of cardiovascular disease. In ECs, exposure to DEHP abrogated the simvastatin-induced NO bioavailability and EC-related functions. Additionally, DEHP abolished the anti-inflammatory effect of simvastatin on the tumor necrosis factor α-induced upregulation of adhesion molecules and monocyte adhesion to ECs. Mechanistically, DEHP blunted the activation of transient receptor potential vanilloid type 1 (TRPV1), which is required for NO production by simvastatin in ECs. Notably, DEHP increased the activity and expression of protein phosphatase 2B (PP2B), a negative regulator of TRPV1 activity. The effect of DEHP on PP2B activation was mediated by the activation of the NADPH oxidase/reactive oxygen species (NOX-ROS) pathway. Inhibition of PP2B activity by pharmacological antagonists prevented the inhibitory effects of DEHP on simvastatin-induced Ca2+ influx, NO bioavailability, and EC migration, proliferation, tube formation, and anti-inflammatory action. Collectively, DEHP activates the NOX-ROS-PP2B pathway, which in turns inhibits TRPV1/Ca2+-dependent signaling and abrogates the statin-conferred pleiotropic protection in ECs.

Phthalate exposure causes browning-like effects on adipocytes in vitro and in vivo.

Mono(2-ethylhexyl)phthalate (MEHP) promotes adipogenesis via PPARγ. PPARγ agonists, e.g., rosiglitazone (RSG), enhance adipocyte browning. However, scientific evidence regarding MEHP as a browning chemical is lacking. This study combined 3T3-L1 adipocytes and C57BL/6J mice to examine the potential roles of MEHP in browning. MEHP and the browning agent RSG caused similar energy metabolism in adipocytes. Both MEHP and RSG caused transcriptional changes involved in browning-associated thermogenesis, energy homeostasis, inflammatory response, and glucose uptake. MEHP-treated adipocytes exhibited brown adipocyte-like characteristics, i.e., increased mitochondrial proton leak, triiodothyronine-induced Bmp8b expression, decreased inflammation, and smaller lipid droplets. Increased PDK4 and PEPCK1 in MEHP/RSG-treated adipocytes could block glucose utilization for mitochondrial respiration. Mitochondrial/peroxisomal biogenesis and fatty acid ß-oxidation in MEHP-treated adipocytes were enhanced. Candidate genes in promoting browning of MEHP-treated adipocytes were highlighted. In di(2-ethylhexyl)phthalate (DEHP)-treated mice, transcriptional changes in white adipose tissue (WAT) were associated with adipocyte differentiation, lipid synthesis, carbohydrate uptake, and WAT/brown adipose tissue (BAT) quantity. PPARγ and NR4A1 were predicted as the top two upstream regulators in orchestrating transcriptional changes. DEHP-treated mice exhibited actively expressed browning marker genes (i.e., Pparg, Adrb1, Adrb3, Ppargc1a, and Ucp1) in WAT, increased blood FGF21 levels, and higher amounts of BAT, supporting the browning-like effects in vivo.

Bromelain Confers Protection against the Non-Alcoholic Fatty Liver Disease in Male C57bl/6 Mice.

We aimed to investigate the effect of bromelain, the extract from stems of pineapples on the high-fat diet (HFD)-induced deregulation of hepatic lipid metabolism and non-alcoholic fatty liver disease (NAFLD), and its underlying mechanism in mice. Mice were daily administrated with HFD with or without bromelain (20 mg/kg) for 12 weeks, and we found that bromelain decreased the HFD-induced increase in body weight by ~30%, organ weight by ~20% in liver weight and ~40% in white adipose tissue weight. Additionally, bromelain attenuated HFD-induced hyperlipidemia by decreasing the serum level of total cholesterol by ~15% and triglycerides level by ~25% in mice. Moreover, hepatic lipid accumulation, particularly that of total cholesterol, free cholesterol, triglycerides, fatty acids, and glycerol, was decreased by 15-30% with bromelain treatment. Mechanistically, these beneficial effects of bromelain on HFD-induced hyperlipidemia and hepatic lipid accumulation may be attributed to the decreased fatty acid uptake and cholesteryl ester synthesis and the increased lipoprotein internalization, bile acid metabolism, cholesterol clearance, the assembly and secretion of very low-density lipoprotein, and the ß-oxidation of fatty acids by regulating the protein expression involved in the above mentioned hepatic metabolic pathways. Collectively, these findings suggest that bromelain has therapeutic value for treating NAFLD and metabolic diseases.