Acid-induced Inflammation Research Articles

Identification of Sec23ip, Part of 14-3-3γ Protein Network, as a Regulator of Acute Steroidogenesis in MA-10 Leydig Cells.

Testosterone production occurs in the Leydig cells of the testes and is essential for virilization, development, reproduction, and quality of life. Although the steroidogenic proteins involved in cholesterol conversion to testosterone (T) are well characterized, the causes of reduced T during fetal, neonatal, and adult life remain uncertain. It is well established that normal cellular function is achieved through fine-tuning of multiple rather than single protein networks. Our objective was to use mass spectrometry (MS)-based proteomics to identify which cellular pathways, other than the steroidogenic machinery, influence testosterone production in MA-10 mouse tumor Leydig cells. The 14-3-3 family of scaffolds mediate protein-protein interactions facilitating the crosstalk between protein networks. We previously showed that in MA-10 cells, 14-3-3γ is a critical regulator of steroidogenesis. Therefore, identifying proteins that interact with 14-3-3γ during steroidogenesis could provide clues into the other networks involved. Using liquid chromatography (LC)-MS, we identified 688 proteins that interact with 14-3-3γ and thus potentially impact MA-10 cell steroidogenesis. The identified proteins belong to multiple protein networks, including endoplasmic reticulum-Golgi cargo sorting and vesicle biogenesis, micro ribonucleic acid-induced gene silencing, inflammation, and vesicle trafficking, to name a few. We found that silencing one of the candidates, Sec23ip, a protein known to be involved in vesicle trafficking, resulted in decreased steroidogenesis. We further showed that in Sec23ip-silenced MA-10 cells, cholesterol mobilization from the cytoplasmic membrane to mitochondria is impaired. Taken together these data suggest that Sec23ip is involved in cholesterol trafficking to supply cholesterol for acute steroidogenesis through its interactions with 14-3-3γ.

Beta-Aminoisobutyric Acid Inhibits Hypothalamic Inflammation by Reversing Microglia Activation.

Beta-aminoisobutyric acid (BAIBA), a natural thymine catabolite, is involved in the beneficial effects of exercise on metabolic disorders. In particular, it has been reported to reverse the inflammatory processes observed in the peripheral organs of animal models of obesity. Therefore, this study aimed to investigate whether BAIBA improves hypothalamic inflammation, which is also tightly coupled with the development of obesity. We observed that treatment with BAIBA effectively reversed palmitic acid-induced hypothalamic inflammation and microglial activation in vivo. Consistent with these findings, we confirmed that BAIBA reversed body weight gain and increased adiposity observed in mice fed with a high-fat diet. Collectively, the current findings evidence the beneficial impacts of BAIBA on the imbalance of energy metabolism linked to hypothalamic inflammation.

Primary biliary cholangitis: pathogenesis and therapeutic opportunities.

Primary biliary cholangitis is a chronic, seropositive and female-predominant inflammatory and cholestatic liver disease, which has a variable rate of progression towards biliary cirrhosis. Substantial progress has been made in patient risk stratification with the goal of personalized care, including early adoption of next-generation therapy with licensed use of obeticholic acid or off-label fibrate derivatives for those with insufficient benefit from ursodeoxycholic acid, the current first-line drug. The disease biology spans genetic risk, epigenetic changes, dysregulated mucosal immunity and altered biliary epithelial cell function, all of which interact and arise in the context of ill-defined environmental triggers. A current focus of research on nuclear receptor pathway modulation that specifically and potently improves biliary excretion, reduces inflammation and attenuates fibrosis is redefining therapy. Patients are benefiting from pharmacological agonists of farnesoid X receptor and peroxisome proliferator-activated receptors. Immunotherapy remains a challenge, with a lack of target definition, pleiotropic immune pathways and an interplay between hepatic immune responses and cholestasis, wherein bile acid-induced inflammation and fibrosis are dominant clinically. The management of patient symptoms, particularly pruritus, is a notable goal reflected in the development of rational therapy with apical sodium-dependent bile acid transporter inhibitors.

The peroxisome proliferator-activated receptor-β/δ antagonist GSK0660 mitigates retinal cell inflammation and leukostasis

Diabetic retinopathy (DR) is triggered by retinal cell damage stimulated by the diabetic milieu, including increased levels of intraocular free fatty acids. Free fatty acids may serve as an initiator of inflammatory cytokine release from Müller cells, and the resulting cytokines are potent stimulators of retinal endothelial pathology, such as leukostasis, vascular permeability, and basement membrane thickening. Our previous studies have elucidated a role for peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) in promoting several steps in the pathologic cascade in DR, including angiogenesis and expression of inflammatory mediators. Furthermore, PPARβ/δ is a known target of lipid signaling, suggesting a potential role for this transcription factor in fatty acid-induced retinal inflammation. Therefore, we hypothesized that PPARβ/δ stimulates both the induction of inflammatory mediators by Müller cells as well the paracrine induction of leukostasis in endothelial cells (EC) by Müller cell inflammatory products. To test this, we used the PPARβ/δ inhibitor, GSK0660, in primary human Müller cells (HMC), human retinal microvascular endothelial cells (HRMEC) and mouse retina. We found that palmitic acid (PA) activation of PPARβ/δ in HMC leads to the production of pro-angiogenic and/or inflammatory cytokines that may constitute DR-relevant upstream paracrine inflammatory signals to EC and other retinal cells. Downstream, EC transduce these signals and increase their synthesis and release of chemokines such as CCL8 and CXCL10 that regulate leukostasis and other cellular events related to vascular inflammation in DR. Our results indicate that PPARβ/δ inhibition mitigates these upstream (MC) as well as downstream (EC) inflammatory signaling events elicited by metabolic stimuli and inflammatory cytokines. Therefore, our data suggest that PPARβ/δ inhibition is a potential therapeutic strategy against early DR pathology.

Allyl isothiocyanate ameliorates lipid accumulation and inflammation in nonalcoholic fatty liver disease via the Sirt1/AMPK and NF-κB signaling pathways.

BACKGROUNDAllyl isothiocyanate (AITC), a classic anti-inflammatory and antitumorigenic agent, was recently identified as a potential treatment for obesity and insulin resistance. However, little is known about its direct impact on the liver.AIMTo investigate the effect and underlying mechanism of AITC in nonalcoholic fatty liver disease (commonly referred to as NAFLD).METHODSTo establish a mouse and cellular model of NAFLD, C57BL/6 mice were fed a high fat diet (HFD) for 8 wk, and AML-12 cells were treated with 200 μM palmitate acid for 24 h. For AITC treatment, mice were administered AITC (100 mg/kg/d) orally and AML-12 cells were treated with AITC (20 μmol/L).RESULTSAITC significantly ameliorated HFD-induced weight gain, hepatic lipid accumulation and inflammation in vivo. Furthermore, serum alanine aminotransferase and aspartate aminotransferase levels were markedly reduced in AITC-treated mice. Mechanistically, AITC significantly downregulated the protein levels of sterol regulatory element­binding protein 1 (SREBP1) and its lipogenesis target genes and upregulated the levels of proteins involved in fatty acid β-oxidation, as well as the upstream mediators Sirtuin 1 (Sirt1) and AMP-activated protein kinase α (AMPKα), in the livers of HFD-fed mice. AITC also attenuated the nuclear factor kappa B (NF-κB) signaling pathway. Consistently, AITC relieved palmitate acid-induced lipid accumulation and inflammation in AML-12 cells in vitro through the Sirt1/AMPK and NF-κB signaling pathways. Importantly, further studies showed that the curative effect of AITC on lipid accumulation was abolished by siRNA-mediated knockdown of either Sirt1 or AMPKα in AML-12 cells.CONCLUSIONAITC significantly ameliorates hepatic steatosis and inflammation by activating the Sirt1/AMPK pathway and inhibiting the NF-κB pathway. Therefore, AITC is a potential therapeutic agent for NAFLD.

A novel small molecule A2A adenosine receptor agonist, indirubin-3'-monoxime, alleviates lipid-induced inflammation and insulin resistance in 3T3-L1 adipocytes.

Saturated free fatty acid-induced adipocyte inflammation plays a pivotal role in implementing insulin resistance and type 2 diabetes. Recent reports suggest A2A adenosine receptor (A2AAR) could be an attractive choice to counteract adipocyte inflammation and insulin resistance. Thus, an effective A2AAR agonist devoid of any toxicity is highly appealing. Here, we report that indirubin-3'-monoxime (I3M), a derivative of the bisindole alkaloid indirubin, efficiently binds and activates A2AAR which leads to the attenuation of lipid-induced adipocyte inflammation and insulin resistance. Using a combination of in silico virtual screening of potential anti-diabetic candidates and in vitro study on insulin-resistant model of 3T3-L1 adipocytes, we determined I3M through A2AAR activation markedly prevents lipid-induced impairment of the insulin signaling pathway in adipocytes without any toxic effects. While I3M restrains lipid-induced adipocyte inflammation by inhibiting NF-κB dependent pro-inflammatory cytokines expression, it also augments cAMP-mediated CREB activation and anti-inflammatory state in adipocytes. However, these attributes were compromised when cells were pretreated with the A2AAR antagonist, SCH 58261 or siRNA mediated knockdown of A2AAR. I3M, therefore, could be a valuable option to intervene adipocyte inflammation and thus showing promise for the management of insulin resistance and type 2 diabetes.

Platelet PI3K Modulates Innate Leukocyte Extravasation during Acid-Induced Acute Lung Inflammation.

Blood platelets are increasingly recognized as modulators of leukocyte effector functions in various pathologies including acute lung injury (ALI). ALI is a life-threatening disease, caused by damage to the alveolar epi- and endothelium. Excessive accumulation of leukocytes leads to severe lung inflammation, resulting in impaired lung function and hypoxemia. Since leukocyte migration is modulated by activated platelets and phosphatidylinositol 3-kinase (PI3K) signaling is involved in platelet function, we aimed to elucidate the effect of PI3K on platelet-mediated immune responses. We generated a mouse model with a platelet-specific deletion of p85α, the most important regulatory subunit of the class IA PI3K, and evaluated platelet function and platelet-leukocyte interactions. Moreover, we analyzed the impact of platelet-specific p85α gene deficiency during sterile peritonitis and acid-induced ALI. In vitro analyses of platelets revealed that lack of p85α led to decreased downstream signaling and diminished expression of surface activation markers, for example, CD62P and CD63, as well as reduced platelet aggregation. Moreover, platelet PI3K essentially mediated direct interactions of platelets with monocytes and neutrophils. In mice, platelet-specific p85α deficiency prevented leukocyte infiltration into the peritoneum and the bronchoalveolar compartment during sterile peritonitis and ALI, respectively. Additionally, the release of the inflammatory cytokine interleukin-12/23 was diminished in platelet p85α-deficient mice during ALI. In contrast to PI3K, neither overexpression nor depletion of platelet phosphatase and tensin homolog, the endogenous antagonist of PI3K, significantly modulated platelet function. Our data indicate a crucial role of platelet PI3K signaling for leukocyte extravasation upon inflammatory stimuli in various diseases models.

Anti-inflammatory effect of artemisinin on uric acid-induced NLRP3 inflammasome activation through blocking interaction between NLRP3 and NEK7

ObjectiveArtemisinin is a potent anti-malarial agent that plays a potent role in regulating inflammatory disorders. NEK7 is a major interacting partner with NLRP3 in NLRP3 inflammasome. The aim of this study was to clarify the anti-inflammatory effect of artemisinin on activation of uric acid-induced NLRP3 inflammasome through regulation of NEK7. MethodsHuman macrophage U937 cells treated with lipopolysaccharide (LPS), monosodium urate (MSU) crystals, or artemisinin were used in in vitro study. Intracellular potassium (K+) level was measured in U937 cells treated with and without artemisinin. Expression of target genes or proteins NEK7, NLRP3, ASC, caspase-1, interleukin-1β (IL-1β), and NF-κB signaling molecules was measured. MSU crystal-induced arthritis model was used for in vivo study. ResultsGout patients showed higher NLRP3 and NEK7 mRNA expression, compared to controls. Enhanced expression of NLRP3, caspase-1, and IL-1β was noted in macrophages treated with LPS (10 ng/ml) and MSU crystals (0.1 mg/ml), which was markedly suppressed by treatment with artemisinin (1, 10, and 100 μM). Artemisinin significantly inhibited interaction between NLRP3 and NEK7 in NLRP3 inflammasome activation. Artemisinin (10 and 100 μM) attenuated intracellular K+ efflux in macrophages stimulated with LPS and MSU crystals. Artemisinin suppressed foot and ankle swelling in MSU crystal-induced arthritis mice. ConclusionThis study revealed that artemisinin inhibited activation of NLRP3 inflammasome by suppressing interaction between NEK7 and NLRP3 in uric acid-induced inflammation.

Kidney Injury Molecule-1 Is Upregulated in Renal Lipotoxicity and Mediates Palmitate-Induced Tubular Cell Injury and Inflammatory Response.

Diabetic nephropathy is increasingly recognized as a major contributor to kidney failure in patients with obesity and type 2 diabetes. This study was designed to identify the molecular mediators of kidney injury associated with metabolic syndrome with or without hyperglycemia. We compared renal gene expression profiles in Zucker lean (ZL), Zucker obese (ZO), and Zucker diabetic (ZD) rats using cDNA microarray with quantitative verification of selected transcripts by real-time PCR. Compared to the 20-week-old ZL control (glucose: 110 ± 8 mg/dL), both prediabetic ZO (glucose: 157 ± 11 mg/dL) and diabetic ZD (glucose: 481 ± 37 mg/dL) rats displayed hyperlipidemia and kidney injury with a high degree of proteinuria. cDNA microarray identified 25 inflammation and injury-related transcriptomes whose expression levels were similarly increased in ZO and ZD kidneys. Among them, kidney injury molecule-1 (KIM-1) was found to be the most highly upregulated in both ZO and ZD kidneys. Immunofluorescence staining of kidney sections revealed a strong correlation between lipid overload and KIM-1 upregulation in proximal tubules of ZO and ZD rats. In cultured primary renal tubular epithelial cells (TECs), administration of saturated fatty acid palmitate resulted in an upregulation of KIM-1, osteopontin, and CD44, which was greatly attenuated by U0126, an inhibitor of extracellular signal-regulated kinase (ERK)1/2. Moreover, knockdown of KIM-1 by siRNA interference inhibited palmitate-induced cleaved caspase-3, osteopontin, and CD44 proteins in primary TECs. Our results indicate that KIM-1 expression is upregulated in renal lipotoxicity and may play an important role in fatty acid-induced inflammation and tubular cell damage in obesity and diabetic kidney disease.

Inflammasome-Independent and Atypical Processing of IL-1β Contributes to Acid Aspiration-Induced Acute Lung Injury.

Inflammation plays a pivotal role in the pathophysiology of gastric aspiration-induced acute lung injury (ALI). However, its mechanism remains unclear. In this study, we investigated the role of NLRP3 inflammasome-driven IL-1β production in a mouse model of acid aspiration-induced inflammation and ALI. Acid aspiration-induced inflammatory responses and ALI in wild-type mice were significantly attenuated in IL-1β-/- mice, but not NLRP3-/- mice. In vitro experiments revealed that severe acidic stress (pH 1.75) induced the processing of pro-IL-1β into its 18-kDa mature form (p18-IL-1β), which was different from the caspase-1-processed 17-kDa form (p17-IL-1β), in human THP-1 macrophages and primary murine macrophages. Deficiency of NLRP3 and caspase-1 had no effect on acidic stress-produced IL-1β. The production of IL-1β by severe acidic stress was prevented by inhibitors of serine proteases [4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride], but not of cysteine proteases (E-64), cathepsin G, or inflammasome. The cathepsin D inhibitor pepstatin A inhibited IL-1β production induced by mild acidic stress (pH 6.2) or lactic acid, but not severe acidic stress. Using mass spectrometry and processing-site mutants of pro-IL-1β, we identified D109 as a novel cleavage site of pro-IL-1β in response to severe acidic stress and calculated the theoretical molecular mass of the mature form to be 18.2 kDa. The bioactivity of acidic stress-produced IL-1β was confirmed by its ability to promote p38 phosphorylation and chemokine upregulation in alveolar epithelial cells. These findings demonstrate a novel mechanism of acid-induced IL-1β production and inflammation independent of NLRP3 inflammasome and provide new insights into the therapeutic strategies for aspiration pneumonitis and ALI.

Oleic acid ameliorates palmitic acid-induced ER stress and inflammation markers in naive and cerulein-treated exocrine pancreas cells.

Dietary fat overload (typical to obesity) increases the risk of pancreatic pathologies through mechanisms yet to be defined. We previously showed that saturated dietary fat induces pancreatic acinar lipotoxicity and cellular stress. The endoplasmic reticulum (ER) of exocrine pancreas cells is highly developed and thus predisposed to stress. We studied the combination of saturated and unsaturated FAs in metabolic and pancreatitis like cerulein (CER)-induced stress states on cellular ER stress.Exocrine pancreas AR42J and rat primary exocrine acinar cells underwent acute (24 h) challenge with different FAs (saturated, monounsaturated) at different concentrations (250 and 500 µM) and in combination with acute CER-induced stress, and were analyzed for fat accumulation, ER stress unfolded protein response (UPR) and immune and enzyme markers. Acute exposure of AR42J and pancreatic acinar cells to different FAs and their combinations increased triglyceride accumulation. Palmitic acid significantly dose-dependently enhanced the UPR, immune factors and pancreatic lipase (PL) levels, as demonstrated by XBP1 splicing and elevation in UPR transcripts and protein levels (Xbp1,Atf6, Atf4, Chop, Tnfα, Tgfβ and Il-6). Exposure to high palmitic levels in a CER-induced stress state synergistically increased ER stress and inflammation marker levels. Exposure to oleic acid did not induce ER stress and PL levels and significantly decreased immune factors in an acute CER-induced stress state. Combination of oleic and palmitic acids significantly reduced the palmitic-induced ER stress, but did not affect the immune factor response. We show that combination of monounsaturated and saturated FAs protects from exocrine pancreatic cellular ER stress in both metabolic and CER-induced stress.

Inhibition of palmitic acid-induced hepatic steatosis and inflammation with Tempol

Inhibition of palmitic acid-induced hepatic steatosis and inflammation with Tempol

Protective Effect of Methane-Rich Saline on Acetic Acid-Induced Ulcerative Colitis via Blocking the TLR4/NF-κB/MAPK Pathway and Promoting IL-10/JAK1/STAT3-Mediated Anti-inflammatory Response.

Ulcerative colitis (UC) is an inflammation-related disease involved in uncontrolled inflammation and oxidative stress and is characterized by high recurrence and relapse risk. As a rising star in gas medicine, methane owns the properties of anti-inflammation, antioxidation, and antiapoptosis. Based on the possible mechanism, we aimed to investigate the effect of methane on UC. Methane-rich saline (MRS) was introduced here, and UC was induced by acetic acid. All the C57BL/6 mice were allocated into groups as follows: control group, colitis model group, colitis treated with salazosulfapyridine (SASP) group, and colitis treated with MRS (1 or 10 ml/kg) groups. Tissue damage, the degree of inflammation, oxidative stress, and apoptosis were evaluated in the study, as well as the TLR4/NF-κB/MAPK and IL-10/JAK1/STAT3 signaling pathways for further exploration of the potential mechanism. The results showed that MRS (1) alleviated tissue damage caused by acetic acid, (2) controlled acetic acid-induced inflammation, (3) inhibited acetic acid-caused oxidative stress, (4) reduced colonic cell apoptosis due to acetic acid, (5) suppressed the TLR-4/NF-κB/MAPK signaling pathway, and (6) activated IL-10/JAK1/STAT3 anti-inflammatory response to improve the injury induced by acetic acid. We conclude that MRS has a protective effect on acetic acid-induced ulcerative colitis in mice via blocking the TLR4/NF-κB/MAPK signaling pathway and promoting the IL-10/JAK1/STAT3-mediated anti-inflammatory response.

One step bulk modification of poly(L-lactic acid) composites with functional additives to improve mechanical and biological properties for cardiovascular implant applications

Poly(L-lactic acid) (PLLA) has been widely used as a promising biomaterial in biomedical applications due to its biodegradability and high mechanical strength. However, because of the inherent brittleness, low impact resistance, and weak thermal stability of PLLA, the modification process is usually required to utilize it for biomedical devices. Furthermore, acidic byproducts resulting from the hydrolysis of PLLA after implantation reduce the pH of the surrounding environment and cause inflammatory responses in the implanted area, leading to the failure of their clinical applications. To this end, here, we demonstrate a novel modification process for the PLLA composite with various functional additives, such as cis-aconitic anhydride (AA), triacetin (TA), isosorbide derivative (ISB), and/or Pluronic® F127 (F). The modified PLLA composite with TA and F (PLLA/TF) showed significantly improved elongation at break and Young’s modulus and retained tensile strength. Moreover, incorporating magnesium hydroxide (MH) nanoparticles (PLLA/TFMH) significantly reduced acid-induced inflammation responses caused by the acidic degradation products of PLLA. Reduced plasma protein adsorption was observed in the PLLA/TFMH. These results suggest that the one step bulk modification of biodegradable PLLA using TA, F, and MH will have great potential in cardiovascular implant applications.

Tetrahydroxy stilbene glucoside alleviates palmitic acid-induced inflammation and apoptosis in cardiomyocytes by regulating miR-129-3p/Smad3 signaling

ObjectiveTetrahydroxy stilbene glucoside (TSG) has been reported to exert a cytoprotective effect against various toxicants. However, the function and mechanism of TSG in palmitic acid (PA)-induced inflammation and apoptosis in cardiomyocytes are still unknown. The present study was designed to investigate the post-transcriptional mechanism in TSG-treated cardiomyocytes’ inflammation and apoptosis induced by PA.MethodsThe mRNA and protein levels were assayed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. The targeted genes were predicted by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. Cell proliferation was analyzed by CCK-8 assay. Annexin V-fluorescein isothiocyanate/polyimide (annexin V-FITC/PI) staining was used to evaluate apoptosis using flow cytometry.ResultsTSG restricted the detrimental effects, including the activated inflammatory response and apoptosis, of PA in cardiomyocytes, as well as the up-regulation of miR-129-3p and down-regulation of p-Smad3 expression. In addition, bioinformatics and experimental analysis suggested that Smad3 was a direct target of miR-129-3p, which could inhibit or enhance the expression of p-Smad by transfection with miR-129-3p mimics or inhibitors, respectively. Furthermore, our results demonstrated that overexpression of Smad3 reversed the inhibition of inflammation and apoptosis by overexpression of miR-129-3p in PA-stimulated cardiomyocytes.ConclusionTSG targeted to miR-129-3p/Smad3 signaling inhibited PA-induced inflammation and apoptosis in cardiomyocytes.

PF-04620110, a Potent Antidiabetic Agent, Suppresses Fatty Acid-Induced NLRP3 Inflammasome Activation in Macrophages.

BackgroundChronic inflammation has been linked to insulin resistance and type 2 diabetes mellitus (T2DM). High-fat diet (HFD)-derived fatty acid is associated with the activation of chronic inflammation in T2DM. PF-04620110, which is currently in phase 1 clinical trials as a selective acyl-CoA:diacylglycerol acyltransferase-1 (DGAT1) inhibitor, is a potent anti-diabetic agent that may be important for the regulation of chronic inflammation in T2DM. However, the mechanisms by which PF-04620110 regulates fatty acid-induced chronic inflammation remain unclear.MethodsPF-04620110 was used in vitro and in vivo. DGAT1-targeting gRNAs were used for deletion of mouse DGAT1 via CRISPR ribonucleoprotein (RNP) system. The activation of NLRP3 inflammasome was measured by immunoblot or cytokine analysis in vitro and in vivo.ResultsHere we show that PF-04620110 suppressed fatty acid-induced nucleotide-binding domain, leucine-rich-repeat-containing receptor (NLR), pyrin-domain-containing 3 (NLRP3) inflammasome activation in macrophages. In contrast, PF-04620110 did not change the activation of the NLR family, CARD-domain-containing 4 (NLRC4), or the absent in melanoma 2 (AIM2) inflammasomes. Moreover, PF-04620110 inhibited K+ efflux and the NLRP3 inflammasome complex formation, which are required for NLRP3 inflammasome activation. PF-04620110 reduced the production of interleukin 1β (IL-1β) and IL-18 and blood glucose levels in the plasma of mice fed HFD. Furthermore, genetic inhibition of DGAT1 suppressed fatty acid-induced NLRP3 inflammasome activation.ConclusionOur results suggest that PF-04620110 suppresses fatty acid-induced NLRP3 inflammasome activation.

Clinopodium chinense Attenuates Palmitic Acid-Induced Vascular Endothelial Inflammation and Insulin Resistance through TLR4-Mediated NF- B and MAPK Pathways.

Elevated palmitic acid (PA) levels are associated with the development of inflammation, insulin resistance (IR) and endothelial dysfunction. Clinopodium chinense (Benth.) O. Kuntze has been shown to lower blood glucose and attenuate high glucose-induced vascular endothelial cells injury. In the present study we investigated the effects of ethyl acetate extract of C. chinense (CCE) on PA-induced inflammation and IR in the vascular endothelium and its molecular mechanism. We found that CCE significantly inhibited PA-induced toll-like receptor 4 (TLR4) expression in human umbilical vein endothelial cells (HUVECs). Consequently, this led to the inhibition of the following downstream adapted proteins myeloid differentiation primary response gene 88, Toll/interleukin-1 receptor domain-containing adaptor-inducing interferon- and TNF receptor-associated factor 6. Moreover, CCE inhibited the phosphorylation of Ikappa B kinase , nuclear factor kappa-B (NF- B), c-Jun N-terminal kinase, extracellular regulated protein kinases, p38-mitogen-activated protein kinase (MAPK) and subsequently suppressed the release of tumor necrosis factor- , interleukin-1 (IL-1 ) and IL-6. CCE also inhibited IRS-1 serine phosphorylation and ameliorated insulin-mediated tyrosine phosphorylation of IRS-1. Moreover, CCE restored serine/threonine kinase and endothelial nitric oxide synthase (eNOS) activation and thus increased insulin-mediated nitric oxide (NO) production in PA-treated HUVECs. This led to reverse insulin mediated endothelium-dependent relaxation, eNOS phosphorylation and NO production in PA-treated rat thoracic aortas. These results suggest that CCE can significantly inhibit the inflammatory response and alleviate impaired insulin signaling in the vascular endothelium by suppressing TLR4-mediated NF- B and MAPK pathways. Therefore, CCE can be considered as a potential therapeutic candidate for endothelial dysfunction associated with IR and diabetes.

Blockage of macrophage migration inhibitory factor (MIF) suppressed uric acid-induced vascular inflammation, smooth muscle cell de-differentiation, and remodeling

Hyperuricemia contributes to vascular injury and dysfunction, yet the potential mechanisms are not well understood. Uric acid (UA) has been found to stimulate macrophage migration inhibitory factor (MIF) up-regulation in renal tubules from rats subjected to UA-induced nephropathy. Given that MIF is able to induce vascular smooth muscle cell (VSMC) de-differentiation (from contractile state to a secretory state), we thus hypothesized that UA-induced vascular injury is via up-regulating of MIF in VSMCs, which enhancing vascular inflammation and VSMC transition. Within a mouse model of UA injection (500 mg/kg, twice/day, 14 days), we measured circulating and vascular MIF levels under UA stimulation at 6 h, day 1, and 14. We tested the efficacy of MIF inhibitor (10 mg/kg, twice/day, 14 days) on UA-induced vascular inflammation and remodeling. High plasma level of UA induced vascular MIF release into the plasma at acute phase. In the chronic phase, the protein level of MIF is up-regulated in the vessels. MIF inhibitor suppressed vascular inflammatory responses, repressed VSMC de-differentiation, and attenuated vascular remodeling and dysfunction following UA stimulation. Knockdown of MIF in cultured VSMCs repressed UA-induced de-differentiation. Our results provided a novel mechanism for MIF-mediated vascular injury in response to UA stimulation, and suggested that anti-MIF interventions may be of therapeutic value in hyperuricemic patients.

High-mobility group box 1 is responsible for monosodium urate crystal-induced inflammation in human U937 macrophages

High-mobility group box 1 (HMGB1) was originally identified as a highly conserved non-histone DNA-binding factor and demonstrated to be a potent mediator in inflammatory diseases. We performed this study to investigate the role of HMGB1 in the pathogenesis of uric acid-induced inflammation in human U937 macrophages. To simulate uric acid-induced inflammation, human U937 macrophages were treated with monosodium urate (MSU) crystals. In addition to determining the effects of MSU crystal treatment on expression of various genes and proteins, cells were transfected with interfering RNA (siRNA) for HMGB1, or caspase-1 and then treated with MSU. Expression of interleukin-1β (IL-1β), IL-18, HMGB1, and caspase-1 was detected in human U937 cells and peripheral blood mononuclear cells (PBMCs) in gout patients and healthy controls by western blot analysis or quantitative real-time polymerase chain reaction. Transcript expression of IL-1β, IL-18, caspase-1, HMGB1 in PBMCs was significantly higher in active gout patients than inactive gout patients and healthy controls. The protein levels of these molecules were significantly increased by stimulation of U937 cells with 0.2 mg/ml MSU crystals. Stimulation of U937 cells with MSU crystals induced translocation of HMGB1 from the nucleus to the cytoplasm and its extracellular release. U937 cells transfected with caspase-1 siRNA had significantly lower HMGB1 expression in the cytoplasm and supernatant than non-transfected cells. Antioxidants, such as N-acetyl-l-cysteine and quercetin, markedly inhibited the nuclear-to-cytoplasmic translocation of HMGB1 and its release into the extracellular milieu. In conclusion, HMGB1, regulated by the enzymatic activity of caspase-1, is a crucial mediator in uric acid-induced inflammation.

BMS309403 decreases fatty acid-induced endoplasmic reticulum stress-associated inflammation in skeletal muscle

BMS309403 decreases fatty acid-induced endoplasmic reticulum stress-associated inflammation in skeletal muscle