Vaccarin prevents titanium particle-induced osteolysis and inhibits RANKL-induced osteoclastogenesis by blocking NF-κB and MAPK signaling pathways.

Wearing titanium particle-induced osteoclastogenesis, accompanied by peri-implant osteolysis, is the main cause of long-term failure of hip prosthesis. Currently, medications used for the prevention and treatment of peri-implant osteolysis show serious side effects. Therefore, development for more effective new drugs with less side effects is extremely urgent. Vaccarin is a natural flavonoid extracted from Vaccaria segetalis, with various biological functions, including antioxidantory, anti-inflammatory, and promotion of angiogenesis. However, the putative role of vaccarin in the inhibition of titanium particle-induced osteolysis has not been reported. In this study, it was indicated that vaccarin could effectively inhibit RANKL-induced osteoclastogenesis, fusion of F-actin rings, bone resorption, and expression of osteoclast marker genes in a dose-dependent manner in vitro. Moreover, vaccarin could also inhibit RANKL-induced osteoclastogenesis via the inhibition of NF-κB and MAPK (p38, ERK, and JNK) signaling pathways, and inhibit the transcription of downstream transcription factors, such as c-Fos and NFATc1. Consistent with in vitro results, this in vivo study showed that vaccarin exhibited an inhibitory effect on titanium particle-induced osteolysis by antiosteoclastogenesis. In conclusion, vaccarin could be a promising agent for preventing and treating peri-implant osteolysis.

Vitamin D alleviates airway remodeling in asthma by down-regulating the activity of Wnt/ß-catenin signaling pathway.

Vitamin D exerts a protective role in asthma; however, the molecular mechanisms underlying the vitamin D-attenuated asthma airway remodeling are yet to be elucidated. In this study, Sprague-Dawley (SD) rats were randomly divided into four groups: control, asthma, vitamin D 50 ng/mL, and vitamin D 100 ng/mL. The treatment with 100 ng/mL vitamin D remarkably reduced the thickness of the airway smooth muscle, collagen deposition, and the alpha-smooth muscle actin (α-SMA) mass and airway inflammation. Conversely, the treatment by vitamin D significantly up-regulated the serum levels of 25(OH)2D3 that were decreased in asthma. The putative signaling pathway of vitamin D was based on Wnt5a and ß-catenin expression assessed by quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR) and Western blot, which revealed that the administration of vitamin D significantly decreased the activity of Wnt/ß-catenin signaling pathway. These results suggested that administration of vitamin D alleviated the airway remodeling in asthma by down-regulating the activity of Wnt/ß-catenin signaling pathway.

Artesunate inhibits RANKL-induced osteoclastogenesis and bone resorption in vitro and prevents LPS-induced bone loss in vivo.

Osteoclasts are multinuclear giant cells responsible for bone resorption in lytic bone diseases such as osteoporosis, arthritis, periodontitis, and bone tumors. Due to the severe side-effects caused by the currently available drugs, a continuous search for novel bone-protective therapies is essential. Artesunate (Art), the water-soluble derivative of artemisinin has been investigated owing to its anti-malarial properties. However, its effects in osteoclastogenesis have not yet been reported. In this study, Art was shown to inhibit the nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis, the mRNA expression of osteoclastic-specific genes, and resorption pit formation in a dose-dependent manner in primary bone marrow-derived macrophages cells (BMMs). Furthermore, Art markedly blocked the RANKL-induced osteoclastogenesis by attenuating the degradation of IκB and phosphorylation of NF-κB p65. Consistent with the in vitro results, Art inhibited lipopolysaccharide (LPS)-induced bone resorption by suppressing the osteoclastogenesis. Together our data demonstrated that Art inhibits RANKL-induced osteoclastogenesis by suppressing the NF-κB signaling pathway and that it is a promising agent for the treatment of osteolytic diseases.

Nitidine chloride prevents OVX-induced bone loss via suppressing NFATc1-mediated osteoclast differentiation.

Nitidine chloride (NC), a bioactive alkaloid isolated from Zanthoxylum nitidum, has been used as a herbal ingredient in toothpaste that prevents cavities for decades. It also displays potential antitumor and anti-inflammation properties. However, its anticatabolic effect on bone is not known. We investigated the effect of NC on osteoclastogenesis, bone resorption and RANKL-induced NF-κB and NFATc1 signalling. In mouse-derived bone marrow monocytes (BMMs), NC suppressed RANKL-induced multinucleated tartrate-resistant acid phosphatase (TRAP)-positive osteoclast formation and bone resorption in a dose dependent manner. NC attenuated the expression of osteoclast marker genes including cathepsin K, D2, calcitonin receptor, NFATc1, and TRAP. Further, NC inhibited RANKL-activated NF-κB and NFATc1 signalling pathways. In vivo study revealed that NC abrogated oestrogen deficiency-induced bone loss in ovariectomized mice. Histological analysis showed that the number of osteoclasts was significantly lower in NC-treated groups. Collectively, our data demonstrate that NC suppressed osteoclastogenesis and prevented OVX-induced bone loss by inhibiting RANKL-induced NF-κB and NFATc1 signalling pathways. NC may be a natural and novel treatment for osteoclast-related bone lytic diseases.

Inhalation of ambroxol inhibits cigarette smoke-induced acute lung injury in a mouse model by inhibiting the Erk pathway.

Oral and injection administration of ambroxol has been clinically used to treat airway disease. However, little is known about its potentials in inhalation therapy. In present studies, we tested the effects of ambroxol by inhalation with intravenous administration, and explored the underlying working mechanism. The mice received 10 cigarettes exposure every day for 4 days. Inhaled solution of ambroxol was aerosolized 20 min before the exposure of cigarette smoke (CS). The effect of ambroxol on the expression of mucoprotein 5 AC (MUC5AC) and proinflammatory cytokines in NCI-H292 cells stimulated with cigarette smoke extract (CSE). Four days of daily inhalation of ambroxol at 3.75 or 7.5mg/ml for 20 min suppressed the accumulation of neutrophils and macrophages in the bronchoalveolar lavage fluid (BALF) and lung tissues, and inhibited increases in the mRNA and protein levels of tumor necrosis factor (TNF)-α, CCL-2 and KC, but not interleukin (IL)-1ß in the CS-exposed mice. Moreover, ambroxol at 3.75 or 7.5mg/ml facilitated airway mucosa cilia clearance, reduced glycosaminoglycans level in BALF and MUC5AC mRNA levels in lung tissues. The effects of ambroxol by inhalation at 7.5mg/ml was comparable to that of ambroxol at 20mg/kg i.v. and dexamethasone at 0.5mg/kg i.p. Using cultured lung epithelial cells, we demonstrated that pretreatment with ambroxol at 2 or 20 µM inhibited the CSE-induced up-regulation of MUC5AC, TNF-α, IL-1ß mRNA levels, which was through inhibiting Erk signaling pathway. Our results demonstrate the beneficial effects of ambroxol as an inhalation replace systemic administration for COPD therapy.

Ambroxol inhalation ameliorates LPS-induced airway inflammation and mucus secretion through the extracellular signal-regulated kinase 1/2 signaling pathway.

Ambroxol, a metabolite of bromhexine, is shown to exert several pharmacological activities, including secretolytic, anti-inflammatory and antioxidant actions. Oral and intravenous administration of ambroxol is useful for the airway inflammatory diseases. However, little is known about its potential in inhalation therapy for lipopolysaccharide (LPS)-induced mucous hypersecretion and inflammatory response. In the present study, we compared the pharmacological effects of ambroxol by inhalation with intravenous administration and preliminarily explored its mechanism of action. Our results demonstrated that ambroxol administered by inhalation inhibited MUC5AC expression, reduced glycosaminoglycan levels, enhanced the function of mucociliary clearance and promoted sputum excretion, suggesting that ambroxol increases expectoration of sputum by reducing its viscosity. Moreover, ambroxol significantly alleviated LPS-induced the influx of inflammatory cells and the extracellular signal-regulated kinase 1/2 (Erk 1/2) expression in lung tissues, and inhibited increases in the mRNA expression of the pro-inflammatory cytokines tumor necrosis factor (TNF)-α, CCL-2 (monocyte chemotactic protein-1), KC (keratinocyte cell protein) and interleukin (IL)-1ß in lung tissues. The secretolytic and anti-inflammatory effects of inhaled ambroxol at a dose of 7.5 mg/ml was comparable to that of ambroxol at 20 mg/ml i.v. and dexamethasone at 0.5 mg/kg i.p. In addition, we found that ambroxol dose-dependently inhibited LPS-induced increases in the mRNA expression of MUC5AC, TNF-α, and IL-1ß in human bronchial epithelial cell (NCI-H292) by inhibiting the Erk signaling pathway. These results demonstrate the beneficial effects of ambroxol in inhalation therapy for the airway inflammatory diseases.

EETs Attenuate Ox-LDL-Induced LTB4 Production and Activity by Inhibiting p38 MAPK Phosphorylation and 5-LO/BLT1 Receptor Expression in Rat Pulmonary Arterial Endothelial Cells.

Cytochrome P-450 epoxygenase (EPOX)-derived epoxyeicosatrienoic acids (EETs), 5-lipoxygenase (5-LO), and leukotriene B4 (LTB4), the product of 5-LO, all play a pivotal role in the vascular inflammatory process. We have previously shown that EETs can alleviate oxidized low-density lipoprotein (ox-LDL)-induced endothelial inflammation in primary rat pulmonary artery endothelial cells (RPAECs). Here, we investigated whether ox-LDL can promote LTB4 production through the 5-LO pathway. We further explored how exogenous EETs influence ox-LDL-induced LTB4 production and activity. We found that treatment with ox-LDL increased the production of LTB4 and further led to the expression and release of both monocyte chemoattractant protein-1 (MCP-1/CCL2) and intercellular adhesion molecule-1 (ICAM-1). All of the above ox-LDL-induced changes were attenuated by the presence of 11,12-EET and 14,15-EET, as these molecules inhibited the 5-LO pathway. Furthermore, the LTB4 receptor 1 (BLT1 receptor) antagonist U75302 attenuated ox-LDL-induced ICAM-1 and MCP-1/CCL2 expression and production, whereas LY255283, a LTB4 receptor 2 (BLT2 receptor) antagonist, produced no such effects. Moreover, in RPAECs, we demonstrated that the increased expression of 5-LO and BLT1 following ox-LDL treatment resulted from the activation of nuclear factor-κB (NF-κB) via the p38 mitogen-activated protein kinase (MAPK) pathway. Our results indicated that EETs suppress ox-LDL-induced LTB4 production and subsequent inflammatory responses by downregulating the 5-LO/BLT1 receptor pathway, in which p38 MAPK phosphorylation activates NF-κB. These results suggest that the metabolism of arachidonic acid via the 5-LO and EPOX pathways may present a mutual constraint on the physiological regulation of vascular endothelial cells.

Cigarette smoke extract-induced BEAS-2B cell apoptosis and anti-oxidative Nrf-2 up-regulation are mediated by ROS-stimulated p38 activation.

Cigarette smoke contains reactive oxygen (ROS) that can cause oxidative stress. It increases the number of apoptotic and necrotic lung cells and further induces the development of chronic airway disease. In this study, we investigated the effects of cigarette smoke extract (CSE) on apoptosis in human bronchial epithelial cells (BEAS-2B). CSE exposure induced ROS generation and p38 mitogen-activated protein kinase (MAPK) activation that are associated with the activation of apoptosis-regulating signal kinase 1 (ASK-1). N-acetylcysteine (a general antioxidant) attenuated the CSE-induced ASK-1 and p38 MAPK activation and cell apoptosis, suggesting a triggering role of ROS in ASK-1/p38 MAPK activation during apoptotic progression. In contrast, the inhibition and knockdown of p38 attenuated the expression of anti-oxidant master NF-E2-related factor 2 (Nrf-2) and CSE-induced apoptosis, suggesting that p38 MAPK modulates Nrf-2 expression and presumably prevents cell apoptosis. Taken together, the data presented in this manuscript demonstrate that the ROS-dependent ASK-1/p38 signaling cascade regulates CSE-induced BEAS-2B cell apoptosis. In addition, anti-oxidative Nrf-2 is also up-regulated by the ROS/p38 signaling cascade in this progression.

EETs alleviate ox-LDL-induced inflammation by inhibiting LOX-1 receptor expression in rat pulmonary arterial endothelial cells.

Oxidized low-density lipoprotein (Ox-LDL) is associated with atherosclerotic events through the modulation of arachidonic acid (AA) metabolism and activation of inflammatory signaling. Cytochrome P450 (CYP) epoxygenase-derived epoxyeicosatrienoic acids (EETs) mitigate inflammation through nuclear factor-κB (NF-κB). In this study, we explored the effects and mechanisms of exogenous EETs on the ox-LDL-induced inflammation of pulmonary artery endothelial cells (PAECs), which were cultured from rat pulmonary arteries. We determined that pre-treatment with 11,12-EET or 14,15-EET attenuated the ox-LDL-induced expression and release of intercellular adhesion molecule-1 (ICAM-1), E-selectin, and monocyte chemoattractant protein-1 (MCP-1) in a concentration-dependent manner. In addition, the ox-LDL-induced expression of CYP2J4 was upregulated by 11,12-EET and 14,15-EET (1µM). Furthermore, the endothelial receptor of lectin-like oxidized low-density lipoprotein (LOX-1) was downregulated in PAECs treated with EETs. The inflammatory responses evoked by ox-LDL (100µg/mL) were blocked by pharmacological inhibitors of Erk1/2 mitogen-activated protein kinase (MAPK) (U0126), p38 MAPK (SB203580), and NF-κB (PDTC). In addition, we confirmed that 11,12-EET suppresses phosphorylation of p38, degradation of IκBα, and activation of NF-κB (p65), whereas 14,15-EET can significantly suppress the phosphorylation of p38 and Erk1/2. Our results indicate that EETs exert beneficial effects on ox-LDL-induced inflammation primarily through the inhibition of LOX-1 receptor upregulation, MAPK phosphorylation, and NF-κB activation and through the upregulation of CYP2J4 expression. This study helps focus the current understanding of the contribution of EETs to the regulation of the inflammation of pulmonary vascular endothelial cells. Furthermore, the therapeutic potential of targeting the EET pathway in pulmonary vascular disease will be highlighted.

Cigarette smoke-induced alveolar epithelial-mesenchymal transition is mediated by Rac1 activation.

BACKGROUND: Epithelial-mesenchymal transition (EMT) is the major pathophysiological process in lung fibrosis observed in chronic obstructive pulmonary disease (COPD) and lung cancer. Smoking is a risk factor for developing EMT, yet the mechanism remains largely unknown. In this study, we investigated the role of Rac1 in cigarette smoke (CS) induced EMT. METHODS: EMT was induced in mice and pulmonary epithelial cells by exposure of CS and cigarette smoke extract (CSE) respectively. RESULTS: Treatment of pulmonary epithelial cells with CSE elevated Rac1 expression associated with increased TGF-ß1 release. Blocking TGF-ß pathway restrained CSE-induced changes in EMT-related markers. Pharmacological inhibition or knockdown of Rac1 decreased the CSE exposure induced TGF-ß1 release and ameliorated CSE-induced EMT. In CS-exposed mice, pharmacological inhibition of Rac1 reduced TGF-ß1 release and prevented aberrations in expression of EMT markers, suggesting that Rac1 is a critical signaling molecule for induction of CS-stimulated EMT. Furthermore, Rac1 inhibition or knockdown abrogated CSE-induced Smad2 and Akt (PKB, protein kinase B) activation in pulmonary epithelial cells. Inhibition of Smad2, PI3K (phosphatidylinositol 3-kinase) or Akt suppressed CSE-induced changes in epithelial and mesenchymal marker expression. CONCLUSIONS AND GENERAL SIGNIFICANCE: Altogether, these data suggest that CS initiates EMT through Rac1/Smad2 and Rac1/PI3K/Akt signaling pathway. Our data provide new insights into the fundamental basis of EMT and suggest a possible new course of therapy for COPD and lung cancer.

AD-1, a novel ginsenoside derivative, shows anti-lung cancer activity via activation of p38 MAPK pathway and generation of reactive oxygen species.

BACKGROUND: Ginseng is a traditional Chinese herb that has been used for thousands of years. In the present study, effects and mechanisms of AD-1 were evaluated for its development as a novel anti-lung cancer drug. METHODS: The cytotoxic activity was evaluated by MTT assay. Flow cytometry was employed to detect cell cycle, apoptosis and ROS. Western blot and immunohistochemistry were used to analyze signaling pathways. Lung cancer xenograft models were established by subcutaneous implantation of A549 or H292 cells into nude mice. RESULTS: AD-1 concentration-dependently reduces lung cancer cell viability without affecting normal human lung epithelial cell viability. In A549 and H292 lung cancer cells, AD-1 induces G0/G1 cell cycle arrest, apoptosis and ROS production. The apoptosis can be attenuated by a ROS scavenger - N-acetylcysteine (NAC). In addition, AD-1 up-regulates the expression of p38 and ERK phosphorylation. Addition of a p38 inhibitor SB203580, suppresses the AD-1-induced decrease in cell viability. Furthermore, genetic silencing of p38 attenuates the expression of p38 and decreases the AD-1-induced apoptosis. Treatment with NAC reduces AD-1-induced p38 phosphorylation, which indicates that ROS generation is involved in the AD-1-induced p38 activation. In mice, oral administration of AD-1 (10-40mg/kg) dose-dependently inhibited the growth of xenograft tumors without affecting body weight and decreases the expression of VEGF, MMP-9 and CD34 in tumor tissue. TUNEL staining confirms that the tumors from AD-1 treated mice exhibit a markedly higher apoptotic index. CONCLUSIONS AND GENERAL SIGNIFICANCE: These data support development of AD-1 as a potential agent for lung cancer therapy.

Apple polyphenol protects against cigarette smoke-induced acute lung injury.

OBJECTIVE: Chronic obstructive pulmonary disease (COPD) is a complex chronic inflammatory disease involving oxidative stress as well as a wide variety of cells activated from smoking cigarettes. There have been disappointingly few therapeutic advances in drug therapy for COPD. Plant polyphenols have been the topic of much research regarding their antioxidant activities and antiinflammatory and immunomodulatory effects. In the present study, we ask whether apple polyphenol provides protection against cigarette smoke (CS)-induced acute lung injury. METHODS: ICR mice were exposed to CS for 4 d with increasing exposure time for up to 6 h per day to elicit epithelial cells injury. One hour before smoke exposure, mice were treated with apple polyphenol (APP) by gavage; all examinations were performed 18 h after the last CS exposure. RESULTS: APP at 30, 100, or 300 mg not only significantly dose-dependently reduced the CS-induced accumulation of inflammatory cells and gene/protein expression of proinflammatory factors both in the lung and in bronchoalveolar lavage fluid, but also significantly reversed oxidative stress in the lungs. Additionally, treatment with APP also significantly regulated the CS-induced imbalance of matrix metalloproteinases-9/tissue inhibitor of metalloproteinase-1 expression in the lungs. To investigate further the possible signaling pathway of APP effects, we examined protein expression of p-P38 MAPK by immunohistochemistry that found treatment with APP significantly decreased the CS-induced increases of p-P38 expression in the lungs. CONCLUSION: Taken together, APP may be a potential dietary nutrient supplement agent to improve quality of life of COPD patients by inhibiting CS-exposed acute lung injury via P38 MAPK signaling pathway.

Shp2 plays an important role in acute cigarette smoke-mediated lung inflammation.

Cigarette smoke (CS), the major cause of chronic obstructive pulmonary disease, contains a variety of oxidative components that were implicated in the regulation of Src homology domain 2-containing protein tyrosine phosphatase 2 (Shp2) activity. However, the contribution of Shp2 enzyme to chronic obstructive pulmonary disease pathogenesis remains unclear. We investigated the role of Shp2 enzyme in blockading CS-induced pulmonary inflammation. Shp2 levels were assessed in vivo and in vitro. Mice (C57BL/6) or pulmonary epithelial cells (NCI-H292) were exposed to CS or cigarette smoke extract (CSE) to induce acute injury and inflammation. Lungs of smoking mice showed increased levels of Shp2, compared with those of controls. Treatment of lung epithelial cells with CSE showed elevated levels of Shp2 associated with the increased release of IL-8. Selective inhibition or knockdown of Shp2 resulted in decreased IL-8 release in response to CSE treatment in pulmonary epithelial cells. In comparison with CS-exposed wild-type mice, selective inhibition or conditional knockout of Shp2 in lung epithelia reduced IL-8 release and pulmonary inflammation in CS-exposed mice. In vitro biochemical data correlate CSE-mediated IL-8 release with Shp2-regulated epidermal growth factor receptor/Grb-2-associated binders/MAPK signaling. Our data suggest an important role for Shp2 in the pathological alteration associated with CS-mediated inflammation. Shp2 may be a potential target for therapeutic intervention for inflammation in CS-induced pulmonary diseases.