Rational design of peptide derivatives for inhibition of MyD88‐mediated toll‐like receptor signaling in human peripheral blood mononuclear cells and epithelial cells exposed to Francisella tularensis

Small molecules were developed to attenuate proinflammatory cytokines resulting from activation of MyD88‐mediated toll‐like receptor (TLR) signaling by Francisella tularensis. Fifty‐three tripeptide derivatives were synthesized to mimic a key BB‐loop region involved in toll‐like/interleukin‐1 receptor recognition (TIR) domain interactions. Compounds were tested for inhibition of TNF‐α, IFN‐γ, IL‐6, and IL‐1β in human peripheral blood mononuclear cells (PBMCs) and primary human bronchial epithelial cells exposed to LPS extracts from F. tularensis. From 53 compounds synthesized and tested, ten compounds were identified as effective inhibitors of F. tularensisLPS‐induced cytokines. Compound stability testing in the presence of human liver microsomes and human serum resulted in the identification of tripeptide derivative 7 that was a potent, stable, and drug‐like small molecule. Target corroboration using a cell‐based reporter assay and competition experiments with MyD88 TIR domain protein supported that the effect of 7 was through MyD88 TIR domain interactions. Compound 7 also attenuated proinflammatory cytokines in human peripheral blood mononuclear cells and bronchial epithelial cells challenged with a live vaccine strain of F. tularensis at a multiplicity of infection of 1:5. Small molecules that target TIR domain interactions in MyD88‐dependent TLR signaling represent a promising strategy toward host‐directed adjunctive therapeutics for inflammation associated with biothreat agent‐induced sepsis.     

Oxidative stress and endocytosis are involved in upregulation of interleukin‐8 expression in airway cells exposed to PM2.5

Inhaled PM2.5 (particulate matter with an aerodynamic diameter of 2.5 μm or less) can induce lung inflammation through released inflammatory mediators from airway cells, such as interleukin‐8 (IL‐8) and tumor necrosis factor alpha (TNF‐α). However, the mechanisms underlying PM2.5‐induced IL‐8 gene expression have not been fully characterized. BEAS‐2B cells (a human bronchial epithelial cell line) and THP‐1 cells (a human macrophage‐like cell line) were used as the in vitro models to investigate the underlying mechanism in this study. IL‐8 expression was increased in the cells treated with PM2.5 in a dose‐dependent manner. The water‐soluble and insoluble fractions of PM2.5 suspension were both shown to induce IL‐8 expression. PM2.5 exposure could obviously induce ROS (reactive oxygen species) generation, indicative of oxidative stress. Pretreatment with the antioxidant N‐acetyl‐l ‐cysteine (NAC) potently inhibited PM2.5‐induced IL‐8 expression. Employment of the transition metal chelators including TPEN (N,N,N',N'‐tetrakis (2‐pyridylmethyl) ethylenediamine) or DFO (desferrioxamine) inhibited IL‐8 expression induced by PM2.5 by over 20% in BEAS‐2B cells, but had minimal effect in THP‐1 cells. Pretreatment with the endocytosis inhibitor CytD markedly blocked IL‐8 expression induced by PM2.5 in both BEAS‐2B and THP‐1 cells. In summary, exposure to PM2.5 induced IL‐8 gene expression through oxidative stress induction and endocytosis in airway cells. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1869–1878, 2016.     

Investigation of inflammation inducing substances in PM2.5 particles by an elimination method using thermal decomposition

The substances associated with PM2.5‐induced inflammatory response were investigated using an elimination method. PM2.5 were heated at temperatures of 120, 250, and 360°C. The results demonstrated microbial substances such as LPS and b‐glucan, and chemicals including BaP, 1,2‐NQ, and 9,10‐PQ were reduced drastically in PM2.5 heated at 120°C. On the other hand, DBA, 7,12‐BAQ, and BaP‐1,6‐Q were not noticeably reduced. Most of these substances had disappeared in PM2.5 heated at 250°C and 360°C. Metals (eg, Fe, Cu, Cr, Ni) in PM2.5 exhibited a slight thermo‐dependent increase. RAW264.7 macrophages with or without NAC were exposed to unheated PM2.5, oxidative stress‐related and unrelated inflammatory responses were induced. PM2.5‐induced lung inflammation in mice is caused mainly by thermo‐sensitive substances (LPS, b‐glucan, BaP, 1,2‐NQ, 9,10‐PQ, etc.). Also, a slight involvement of thermo‐resistant substances (DBA, 7,12‐BAQ, BaP‐1,6‐Q, etc.) and transition metals was observed. The thermal decomposition method could assist to evaluate the PM2.5‐induded lung inflammation.     

Differences in allergic inflammatory responses in murine lungs: comparison of PM2.5 and coarse PM collected during the hazy events in a Chinese city

Urban particulate matter (PM) is associated with an increase in asthma. PM2.5 (<PM2.5?μm) and coarse PM (CPM: PM2.5–PM10?μm) were collected from the air in a Chinese city during haze events. The amounts of polycyclic aromatic hydrocarbons (PAHs) were higher in PM2.5 than in CPM. Conversely, microbial elements LPS and β-glucan were much higher in CPM than in PM2.5. Concentrations of Si, Al, Fe, and Ti in CPM were greater than in PM2.5, while Pb, Cu and As concentrations were lower than in PM2.5. When RAW264.7 cells were treated with PM2.5 and CPM, the pro-inflammatory response in the cells was associated with the microbial element levels and attenuated partly by both polymyxin B (PMB) and N-acetylcystein (NAC). The expression of the oxidative stress response gene heme oxygenase1 was associated with PAHs levels. The exacerbating effects of the two-types of PM on murine lung eosinophilia were compared to clarify the role of toxic materials. When BALB/c mice were intratracheally instilled with PM2.5 or CPM (total 0.4?mg)?+?ovalbumin (OVA), both exacerbated lung eosinophilia along with allergy-relevant biological indicators, such as OVA-specific IgE in serum; enhancement of lung pathology when compared with counterpart samples without OVA. The exacerbating effects were greater in microbial element-rich CPM than in organic chemical-rich PM2.5. These results indicate that microbial elements have more potently exacerbating effects on the development of lung eosinophilia than do organic chemicals. In addition, oxidative stress and transition metals might be associated with the exacerbation of this negative effect.     

Role of iron and oxidative stress in the exacerbation of allergic inflammation in murine lungs caused by urban particulate matter <2.5 μm and desert dust

Simultaneous exposure of lipopolysaccharide (LPS) and urban particulate matter <2.5 μm (PM2.5) or desert dust exacerbated murine asthma. In the present study, the role of iron (Fe) contained in particles and oxidative stress was investigated using Fe chelator deferoxamine (DFO) and oxidative stress scavenger N‐acetylcysteine (NAC) in a murine asthma model exacerbated by LPS + PM2.5 or LPS + Asian sand dust (ASD). When BALB/c mice were intratracheally challenged with ovalbumin (OVA) + LPS and either urban PM2.5 or ASD, LPS + PM2.5 and LPS + ASD caused exacerbation of OVA‐induced lung eosinophilia along with T‐helper 2 cytokine and eosinophil‐relevant chemokine production in bronchoalveolar lavage fluid as well as the production of OVA‐specific IgE in serum. LPS + PM2.5 with NAC tended to reduce the lung eosinophilia compared to the LPS + PM2.5 host, whereas LPS + PM2.5 with DFO did not reduce them. LPS + ASD with NAC moderately reduced the lung eosinophilia compared to the LPS + ASD host. LPS + ASD with DFO drastically reduced the lung eosinophilia compared to the LPS + ASD host. The concentration of Fe in urban PM2.5 and ASD were almost the same. However, the concentrations of trace metals Pb, Cu, As, Ni, Cr, Mo, Sb, Co, Se and Cd were greater in PM2.5 than in ASD. These results suggested that Fe and oxidative stress are at least partly involved in lung eosinophilia exacerbation caused by LPS + ASD. However, trace metals (except Fe) might also be involved in lung eosinophilia exacerbated by LPS + PM2.5.     

PM10‐biogenic fraction drives the seasonal variation of proinflammatory response in A549 cells

PM10 was collected in a Milan urban site, representative of the city air quality, during winter and summer 2006. Mean daily PM10 concentration was 48 μg m^?3 during summer and 148 μg m^?3 during winter. Particles collected on Teflon filters were chemically characterized and the endotoxin content determined by the LAL test. PM10‐induced cell toxicity, assessed with MTT and LDH methods, and proinflammatory potential, monitored by IL‐6 and IL‐8 cytokines release, were investigated on the human alveolar epithelial cell line A549 exposed to increasing doses of PM. Besides untreated cells, exposure to inert carbon particles (2–12 μm) was also used as additional control. Both cell toxicity and proinflammatory potency resulted to be higher for summer PM10 with respect of winter PM10, with IL‐6 showing the highest dose‐dependent release. The relevance of biogenic components adsorbed onto PM10 in eliciting the proinflammatory mediators release was investigated by inhibition experiments. Polymixin B (Poly) was used to inhibit particle‐bind LPS while Toll‐like receptor‐2 antibody (a‐TLR2) to specifically block the activation of this receptor. While cell viability was not modulated in cells coexposed to PM10 and Poly or a‐TLR2 or both, inflammatory response did it, with IL‐6 release being the most inhibited. In conclusion, Milan PM10‐induced seasonal‐dependent biological effects, with summer particles showing higher cytotoxic and proinflammatory potential. Cytotoxicity seemed to be unaffected by the PM biogenic components, while inflammation was significantly reduced after the inhibition of some biogenic activated pathways. Besides, the PM‐associated biogenic activity does not entirely justify the PM‐induced inflammatory effects. © 2010 Wiley Periodicals, Inc. Environ Toxicol 2012.     

Structure‐Based Design and Synthesis of a Small Molecule that Exhibits Anti‐inflammatory Activity by Inhibition of MyD88‐mediated Signaling to Bacterial Toxin Exposure

Both Gram‐positive and Gram‐negative pathogens or pathogen‐derived components, such as staphylococcal enterotoxins (SEs) and endotoxin (LPS) exposure, activate MyD88‐mediated pro‐inflammatory cellular immunity for host defense. However, dysregulated MyD88‐mediated signaling triggers exaggerated immune response that often leads to toxic shock and death. Previously, we reported a small molecule compound 1 mimicking BB‐loop structure of MyD88 was capable of inhibiting pro‐inflammatory response to SEB exposure in mice. In this study, we designed a dimeric structure compound 4210 covalently linked with compound 1 by a non‐polar cyclohexane linker which strongly inhibited the production of pro‐inflammatory cytokines in human primary cells to SEB (IC₅₀ 1–50 μm ) or LPS extracted from Francisella tularensis, Escherichia coli, or Burkholderia mallei (IC₅₀ 10–200 μm ). Consistent with cytokine inhibition, in a ligand‐induced cell‐based reporter assay, compound 4210 inhibited Burkholderia mallei or LPS‐induced MyD88‐mediated NF‐kB‐dependent expression of reporter activity (IC₅₀ 10–30 μm ). Furthermore, results from a newly expressed MyD88 revealed that 4210 inhibited MyD88 dimer formation which is critical for pro‐inflammatory signaling. Importantly, a single administration of compound 4210 in mice showed complete protection from lethal toxin challenge. Collectively, these results demonstrated that compound 4210 inhibits toxin‐induced inflated pro‐inflammatory immune signaling, thus displays a potential bacterial toxin therapeutic.     

Palmitoleic acid reduces the inflammation in LPS‐stimulated macrophages by inhibition of NFκB,independently of PPARs

Palmitoleic acid (PM , 16:1n‐7) has anti‐inflammatory properties that could be linked to higher expression of PPAR α, an inhibitor of NF κB. Macrophages play a major role in the pathogenesis of chronic inflammation, however, the effects of PM on macrophages are underexplored. Thus, we aimed to investigate the effects of PM in activated macrophages as well the role of PPAR α. Primary macrophages were isolated from C57BL /6 wild type (WT ) and PPAR α knockout (KO ) mice, cultured under standard conditions and exposed to lipopolysaccharides LPS (2.5 μg/ml ) and PM 600 μmol/L conjugated with albumin for 24 hours. The stimulation with LPS increased the production of interleukin (IL )‐6 and IL ‐1β while PM decreased the production of IL ‐6 in WT macrophages. In KO macrophages, LPS increased the production of tumour necrosis factor (TNF )‐α and IL ‐6 and PM decreased the production of TNF α. The expression of inflammatory markers such NF κB and IL 1β were increased by LPS and decreased by PM in both WT and KO macrophages. PM reduced the expression of MyD88 and caspase‐1 in KO macrophages, and the expression of TLR 4 and HIF ‐1α in both WT and KO macrophages, although LPS had no effect. CD 86, an inflammatory macrophage marker, was reduced by PM independently of genotype. PM increased PPAR γ and reduced PPAR β gene expression in macrophages of both genotypes, and increased ACOX ‐1 expression in KO macrophages. In conclusion, PM promotes anti‐inflammatory effects in macrophages exposed to LPS through inhibition of inflammasome pathway, which was independent of PPAR α, PPAR ? and AMPK , thus the molecular mechanisms of anti‐inflammatory response caused by PM is still unclear.     

The toll like receptor 4‐myeloid differentiation factor 88 pathway is essential for particulate matter‐induced activation of CD4‐positive cells

Asian sand dust (ASD), a type of particulate matter (PM) found in Asia, can be transported to East Asia. We recently found that acute splenic inflammation is induced by ASD in mouse models. In this study, we examined the effect of sub‐chronic ASD exposure on mouse immune cells. Mice were intratracheally administered ASD once every 2 weeks for 8 weeks and killed 24 hours after the final administration. Wild‐type (WT) mice showed increased cell viability after ASD administration. In contrast, ASD administration induced splenocyte activation in toll‐like receptor (TLR)2^?/?, but not TLR4^?/? mice. Furthermore, concanavalin A‐induced interleukin‐2 production increased after ASD administration in WT and TLR2^?/? mice, but not in TLR4^?/? or myeloid differentiation factor (MyD)88^?/? mice. Immunoblotting demonstrated that nuclear factor κB (NF‐κB) was activated in WT mice, but not in TLR4^?/? or MyD88^?/? mice. The NF‐κB‐dependent gene products CDK2 and intercellular cell adhesion molecule‐1 were upregulated upon ASD administration in WT mice, but not in TLR4^?/? or MyD88^?/? mice. Furthermore, the particles themselves, rather than particle constituents, activated NF‐κB in CD4‐positive cells through the TLR4 or MyD88 pathway. Taken together, these results indicate that particle‐induced splenic inflammation occurs via TLR4‐MyD88 signaling.     

Instillation of coarse ash particulate matter and lipopolysaccharide produces a systemic inflammatory response in mice

Coronary ischemic events increase significantly following a "bad air" day. Ambient particulate matter (PM10) is the pollutant most strongly associated with these events. PM10 produces inflammatory injury to the lower airways. It is not clear, however, whether pulmonary inflammation translates to a systemic response. Lipopolysaccharide (LPS) is a proinflammatory molecule often associated with the coarse fraction of PM. It was hypothesized that PM>2.5 from coal plus LPS induce pulmonary inflammation leading to a systemic inflammatory response. Mice were intratracheally instilled with saline, PM (200 microg), PM + LPS10 (PM + 10 microg LPS), or PM + LPS100 (PM + 100 microg LPS). Eighteen hours later, histologic analysis was performed on lungs from each group. Pulmonary and systemic inflammation were assessed by measuring the proinflammatory cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 in the pulmonary supernatant and plasma. In a follow-up study, the effects of LPS alone were assessed. Histologic analysis revealed a dose-dependent elevation in pulmonary inflammation with all treatments. Pulmonary TNF-alpha and IL-6 both increased significantly with PM + LPS100 treatment. Regarding plasma, TNF-alpha significantly increased in both PM + LPS10 and PM + LPS100 treatments. For plasma IL-6, all groups tended to rise with a significant increase in the PM + LPS100 group. The results of the follow-up study indicate that the responses to PM + LPS were not due to LPS alone. These results suggest that coarse coal fly ash PM>2.5 combined with LPS produced pulmonary and systemic inflammatory responses. The resulting low-level systemic inflammation may contribute to the increased severity of ischemic heart disease observed immediately following a bad air day.     

Lipopolysaccharide levels adherent to PM2.5 play an important role in particulate matter induced‐immunosuppressive effects in mouse splenocytes

Epidemiological studies show that exposure to ambient particulate matter (PM) is associated with serious adverse health effects, including, but not limited to, those on the respiratory system. In the present study, we investigated the splenic response in mice administered PM of ≤ 2.5 μ m diameter (PM2.5). Male BALB/c mice (7 or 8 weeks old) were intratracheally administered PM2.5 (0.1 mg) four times, at 2 week intervals, and dissected 24 h after the final administration. The effect of six types of PM2.5, collected in Shenyang or Beijing (China) and Kitakyushu (Japan), on splenocytes was examined. Our results revealed a strong correlation between the levels of lipopolysaccharide (LPS), but not that of β‐glucan and polycyclic aromatic hydrocarbons, attached to PM2.5 and the effect of PM2.5 on cell activity. PM2.5 with a low amount of LPS (PM2.5LL) reduced splenocyte mitogen‐induced proliferation and cytokine production compared with that in control mice. The suppressive effects of PM2.5LL on proliferation and interleukin‐2 production in splenocytes were rescued by the antioxidant N‐acetylcysteine. Expression of heme oxygenase‐1 was elevated after PM2.5LL administration, particularly in CD11b ⁺ cells, while no elevation was observed in CD4⁺, CD8⁺ or B220⁺ cells. Further, dissociation of the nuclear factor erythroid 2‐related factor 2 from Kelch‐like ECH‐associating protein 1 was observed in splenocytes of PM2.5LL‐administered mice. These data suggest that LPS attached to PM2.5 modulates the splenocyte immune responses to PM2.5.     

Chlorogenic acid reduces liver inflammation and fibrosis through inhibition of toll-like receptor 4 signaling pathway

Chlorogenic acid (CGA) is a type of polyphenol with anti-inflammatory, antioxidant activities. Our previous studies showed CGA could efficiently inhibit carbon tetrachloride (CCl₄)-induced liver fibrosis in rats. However, the specific underlying mechanism remains unclear. The aim of this study is to investigate the effects of CGA on liver inflammation and fibrosis induced by CCl₄ and whether they are related to inhibition of toll-like receptor 4 (TLR4) signaling pathway. Male Sprague-Dawley (SD) rats were administrated CCl₄ together with or without CGA for 8 weeks. Histopathological and biochemical analyses were carried out. The mRNA and protein expression levels of proinflammatory and profibrotic mediators were detected by RT-PCR and Western blot, respectively. The levels of serum proinflammatory cytokines were detected by ELISA. CGA significantly attenuated CCl₄-induced liver damage and symptoms of liver fibrosis, accompanied by reduced serum transaminase levels, collagen I and α-smooth muscle actin (α-SMA) expression. As compared with the CCl₄-treated group, the expression levels of TLR4, myeloid differentiation factor 88 (MyD88), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were reduced in the treatment group of CCl₄ and CGA, whereas bone morphogenetic protein and activin membrane-bound inhibitor (Bambi) expression was increased. CGA also suppressed CCl₄ induced nuclear factor-κB (NF-κB) activation. Moreover, the hepatic mRNA expression and serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were significantly increased in CCl₄-treated rats and attenuated by co-treatment with CGA. Our data indicate that CGA can efficiently inhibit CCl₄-induced liver fibrosis in rats and the protective effect may be due to the inhibition of TLR4/MyD88/NF-κB signaling pathway.     

Xiao-Xu-Ming decoction extract alleviates LPS-induced neuroinflammation associated with down-regulating TLR4/MyD88 signaling pathway in vitro and in vivo

In the present study, we aimed to investigate the effects of Xiao-Xu-Ming decoction extract (XXM) on lipopolysaccaride (LPS)-induced neuroinflammation invitro and invivo. Invitro, the microglia BV2 cells were treated with 200 ng/mL LPS for 24 h to induce inflammatory responses. Invivo, mice were treated with 5 mg/kg LPS to induce inflammatory responses. The NO level was determined by Griess Reagents. The levels of IL-1β, IL-6, TNF-α and MCP-1 were determined by ELISA. The expressions of Iba-1, TLR4 and MyD88 at the protein levels were determined by Western blotting analysis. The mRNA levels of TLR4 and MyD88 were determined by real-time PCR. Invitro, XXMsignificantly reduced the levels of various pro-inflammatory factors, including NO, IL-1β, IL-6 and TNF-α, induced by LPS in the supernatant of BV2 cells and suppressedexpressions of inflammatory proteins TLR4 and MyD88 induced by LPS in BV2 cells. Invivo, XXM significantly inhibited microglia activation, attenuated LPS-induced inflammatory factors and chemokine production, such as IL-1β, IL-6, TNF-α and MCP-1, andinhibited the expressions of inflammatory proteins including TLR4 and MyD88, in the cortex of LPS-induced mice. Our findings suggested that XXM could attenuate LPS-induced neuroinflammation via down-regulating TLR4/MyD88 signaling pathway.     

Baicalin prevents LPS-induced activation of TLR4/NF-κB p65 pathway and inflammation in mice via inhibiting the expression of CD14

Previous studies have shown that baicalin,an active ingredient of the Chinese traditional medicine Huangqin,attenuates LPS-induced inflammation by inhibiting the activation of TLR4/NF-κBp65 pathway,but how it affects this pathway is unknown.It has been shown that CD14 binds directly to LPS and plays an important role in sensitizing the cells to minute quantities of LPS via chaperoning LPS molecules to the TLR4/MD-2 signaling complex.In the present study we investigated the role of CD14 in the anti-inflammatory effects of baicalin in vitro and in vivo.Exposure to LPS(1μg/mL)induced inflammatory responses in RAW264.7 cells,evidenced by marked increases in the expression of MHC II molecules and the secretion of NO and IL-6,and by activation of MyD88/NF-κB p65 signaling pathway,as well as the expression of CD14 and TLR4.These changes were dose-dependently attenuated by pretreatment baicalin(12.5–50μM),but not by baicalin post-treatment.In RAW264.7 cells without LPS stimulation,baicalin dose-dependently inhibit the protein and mRNA expression of CD14,but not TLR4.In RAW264.7 cells with CD14 knockdown,baicalin pretreatment did not prevent inflammatory responses and activation of MyD88/NF-κB p65 pathway induced by high concentrations(1000μg/mL)of LPS.Furthermore,baicalin pretreatment also inhibited the expression of CD14 and activation of MyD88/NF-κB p65 pathway in LPS-induced hepatocyte-derived HepG2 cells and intestinal epithelial-derived HT-29 cells.In mice with intraperitoneal injection of LPS and in DSS-induced UC mice,oral administration of baicalin exerted protective effects by inhibition of CD14 expression and inflammation.Taken together,we demonstrate that baicalin pretreatment prevents LPS-induced inflammation in RAW264.7 cells in CD14-dependent manner.This study supports the therapeutic use of baicalin in preventing the progression of LPS-induced inflammatory diseases.     

Dioscin reduces lipopolysaccharide-induced inflammatory liver injury via regulating TLR4/MyD88 signal pathway

We previously reported the effects of dioscin against carbon tetrachloride-, acetaminophen- and alcohol-induced acute liver damage. However, its effect on lipopolysaccharide (LPS)-induced inflammatory liver injury remains unknown. In the present work, liver injury in mice and rats was induced by LPS, and dioscin was intragastrically administered for 7 days. In vitro, the AML-12 cells and HepG-2 cells were treated with LPS after dioscin treatment. The results showed that dioscin not only markedly reduced serum ALT, AST levels and relative liver weights, but also restored cell injury caused by LPS. In mechanism study, dioscin significantly attenuated inflammation through down-regulating the levels of toll-like receptor (TLR) 4, myeloid differentiation factor 88 (MyD88), interleukin-1 receptor-associated kinase 1 (IRAK1), tumor necrosis factor receptor-associated factor 6 (TRAF6), phosphorylated inhibitor of nuclear factor κB kinase (p-IKK), phosphorylated inhibitor of nuclear factor κB alpha (p-IκBα), phosphorylated nuclear factor κB p65 (p-NF-κB p65), high-mobility group protein 1 (HMGB-1), interleukin (IL)-1, IL-6 and tumor necrosis factor-α (TNF-α). TLR4 overexpression was also decreased by dioscin, leading to the markedly decreased levels of MyD88, IRAK1, TRAF6, p-IKK, p-IκBα, p-NF-κB p65 and HMGB-1. Suppression of MyD88 by ST2825 eliminated the inhibitory effects of dioscin on the levels of IRAK1, TRAF6, p-IKK, p-IκBα, p-NF-κB p65, HMGB-1, IL-1β, IL-6 and TNF-α. Our results suggested that dioscin exhibited protective effect against LPS-induced liver injury via altering TLR4/MyD88 pathway, which should be developed as one potent candidate for the treatment of acute inflammatory liver injury in the future.     

Effects of two Asian sand dusts transported from the dust source regions of Inner Mongolia and northeast China on murine lung eosinophilia

The quality and quantity of toxic materials adsorbed onto Asian sand dust (ASD) are different based on dust source regions and passage routes. The aggravating effects of two ASDs (ASD1 and ASD2) transported from the source regions of Inner Mongolia and northeast China on lung eosinophilia were compared to clarify the role of toxic materials in ASD. The ASDs contained different amounts of lipopolysaccharides (LPS) and β-glucan (ASD1 < ASD2) and SiO₂ (ASD1 > ASD2). CD-1 mice were instilled intratracheally with ASD1, ASD2 and/or ovalbumin (OVA) four times at 2-week intervals. ASD1 and ASD2 enhanced eosinophil recruitment induced by OVA in the submucosa of the airway, with goblet cell proliferation in the bronchial epithelium. ASD1 and ASD2 synergistically increased OVA-induced eosinophil-relevant cytokines interleukin-5 (IL-5), IL-13 (ASD1 < ASD2) and chemokine eotaxin (ASD1 > ASD2) in bronchoalveolar lavage fluid. ASD2 aggravating effects on lung eosinophilia were greater than ASD1. The role of LPS and β-glucan in ASD2 on the production of pro-inflammatory mediators was assessed using in vitro bone marrow-derived macrophages (BMDMs) from wild type, Toll-like receptor 2-deficient (TLR2 −/−), TLR4 −/−, and MyD88 −/− mice (on Balb/c background). ASD2-stimulated TLR2 −/− BMDMs enhanced IL-6, IL-12, TNF-α, MCP-1 and MIP-1α secretion compared with ASD2-stimulated TLR4 −/− BMDMs. Protein expression from ASD2-stimulated MyD88 −/− BMDM were very low or undetectable. The in vitro results indicate that lung eosinophilia caused by ASD is TLR4 dependent. Therefore, the aggravation of OVA-related lung eosinophilia by ASD may be dependent on toxic substances derived from microbes, such as LPS, rather than SiO₂.     

Low dose of fine particulate matter (PM2.5) can induce acute oxidative stress,inflammation and pulmonary impairment in healthy mice

Air pollution is associated with morbidity and mortality induced by respiratory diseases. However, the mechanisms therein involved are not yet fully clarified. Thus, we tested the hypothesis that a single acute exposure to low doses of fine particulate matter (PM2.5) may induce functional and histological lung changes and unchain inflammatory and oxidative stress processes. PM2.5 was collected from the urban area of São Paulo city during 24?h and underwent analysis for elements and polycyclic aromatic hydrocarbon contents. Forty-six male BALB/c mice received intranasal instillation of 30 μL of saline (CTRL) or PM2.5 at 5 or 15?μg in 30 μL of saline (P5 and P15, respectively). Twenty-four hours later, lung mechanics were determined. Lungs were then prepared for histological and biochemical analysis. P15 group showed significantly increased lung impedance and alveolar collapse, as well as lung tissue inflammation, oxidative stress and damage. P5 presented values between CTRL and P15: higher mechanical impedance and inflammation than CTRL, but lower inflammation and oxidative stress than P15. In conclusion, acute exposure to low doses of fine PM induced lung inflammation, oxidative stress and worsened lung impedance and histology in a dose-dependent pattern in mice.     

MiR‐146a regulates PM1‐induced inflammation via NF‐κB signaling pathway in BEAS‐2B cells

Exposure to particulate matter (PM) leads to kinds of cardiopulmonary diseases, such as asthma, COPD, arrhythmias, lung cancer, etc., which are related to PM‐induced inflammation. We have found that PM_2.5 (aerodynamics diameter <2.5 µm) exposure induces inflammatory response both in vivo and in vitro. Since the toxicity of PM is tightly associated with its size and components, PM₁ (aerodynamics diameter <1.0 µm) is supposed to be more toxic than PM_2.5. However, the mechanism of PM₁‐induced inflammation is not clear. Recently, emerging evidences prove that microRNAs play a vital role in regulating inflammation. Therefore, we studied the regulation of miR‐146a in PM₁‐induced inflammation in human lung bronchial epithelial BEAS‐2B cells. The results show that PM₁ induces the increase of IL‐6 and IL‐8 in BEAS‐2B cells and up‐regulates the miR‐146a expression by activating NF‐κB signaling pathway. Overexpressed miR‐146a prevents the nuclear translocation of p65 through inhibiting the IRAK1/TRAF6 expression, and downregulates the expression of IL‐6 and IL‐8. Taken together, these results demonstrate that miR‐146a can negatively feedback regulate PM₁‐induced inflammation via NF‐κB signaling pathway in BEAS‐2B cells.