Inducible nitric oxide synthase evoked nitric oxide counteracts capsaicin-induced airway smooth muscle contraction, but exacerbates plasma extravasation

Role of nitric oxide, bradykinin B2 receptor, and TRPV1 in the airway alterations caused by simvastatin in rats

Dry cough has been reported in patients receiving statin therapy. However, the underlying mechanism or other possible alterations in the airways induced by statins remain unknown. Thus, the aim of this study was to evaluate whether simvastatin promotes alterations in airways, such as bronchoconstriction and plasma extravasation, as well as the mechanism involved in these events. Using methods to detect alterations in airway resistance and plasma extravasation, we demonstrated that simvastatin [20 mg/kg, intravenous (i.v.)] caused plasma extravasation in the trachea (79.8 + 14.8 μg/g/tissue) and bronchi (73.3 + 8.8 μg/g/tissue) of rats, compared to the vehicle (34.2 + 3.6 μg/g/tissue and 29.3 + 5.3 μg/g/tissue, respectively). NG-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg, intraperitoneal), a nitric oxide (NO) synthase inhibitor, Icatibant [HOE 140, 10 nmol/50 μl, intratracheal (i.t.)], a bradykinin B2 antagonist, and capsazepine (100 nmol/50 μl, i.t.), a TRPV1 antagonist, attenuated simvastatin-induced plasma extravasation. Simvastatin (5, 10 and 20 mg/kg) did not cause bronchoconstriction per se, but exacerbated the bronchoconstrictive response to bradykinin (30 nmol/kg, i.v.), a B2 agonist (0.7 + 0.1 ml/H2O), or capsaicin (30 nmol/kg, i.v.), a TRPV1 agonist (0.8 + 0.1 ml/H2O), compared to the vehicle (0.1 + 0.04 ml/H2O and 0.04 + 0.01 ml/H2O, respectively). The bronchoconstriction elicited by bradykinin (100 nmol/kg, i.v.) in simvastatin non-treated rats was inhibited by L-NAME. The exacerbation of bronchoconstriction induced by bradykinin or capsaicin in simvastatin-treated rats was inhibited by L-NAME, HOE 140 or capsazepine. These results suggest that treatment with simvastatin promotes the release of bradykinin, which, via B2 receptors, releases NO that can then activate the TRPV1 to promote plasma extravasation and bronchoconstriction.

Fruiting Bodies of Antrodia cinnamomea and Its Active Triterpenoid, Antcin K, Ameliorates N-Nitrosodiethylamine-Induced Hepatic Inflammation, Fibrosis and Carcinogenesis in Rats

Antrodia cinnamomea (A. cinnamomea), a popular medicinal mushroom in Taiwan, is widely used to prevent or treat liver diseases. Systematic studies on the anti-inflammatory effect of A. cinnamomea and its molecular mechanisms have not yet been fully investigated. HPLC fingerprint analysis identified seven ergostane-type triterpenoids from A. cinnamomea water extract (ACW), including high amounts of Antcin K (AC), Antcin C, Antcin H, Dehydrosulphurenic acid, Antcin B, Antcin A and Dehydroeburicoic acid. Here, we explored the effects and mechanisms of ACW and the highest content AC on N-nitrosodiethylamine (DEN) induced liver inflammation, fibrosis and carcinogenesis in rats. In the in vitro study, we measured how ACW and AC dose-dependently scavenged O[Formula: see text], H₂O₂ and HOCl by a chemiluminescence analyzer. In the in vivo experiment, oral intake ACW and AC significantly inhibited DEN-enhanced hepatocellular inflammation, fibrosis and carcinoma by pathologic observation, the elevated bile and liver reactive oxygen species (ROS) amounts, plasma [Formula: see text]-glutamyl transpeptidase, and oxidative stress including 3-nitrotyrosine, 4-hydroxynonenal and Kuppfer cell infiltration (ED-1 stains) in the inflammatory livers. DEN enhanced nuclear factor-[Formula: see text]B (NF-[Formula: see text]B) translocation, whereas ACW and AC suppressed DEN-enhanced NF-[Formula: see text]B translocation through the inhibition of its upstream signaling of p85/phosphoinositide-3-kinase, mitogen activated protein kinase and CYP2E1 expression. In conclusion, DEN can induce hepatocellular inflammation, fibrosis and carcinoma by increasing NF-[Formula: see text]B translocation to the nucleus, and oxidative injury. ACW and its active component, Antcin K, counteract DEN-induced hepatic injury and inflammation by the protective and therapeutic mechanisms of a direct scavenging ROS activity and an upregulation of anti-oxidant defense mechanisms.

Sensory nerves in lung and airways

Sensory nerves innervating the lung and airways play an important role in regulating various cardiopulmonary functions and maintaining homeostasis under both healthy and disease conditions. Their activities conducted by both vagal and sympathetic afferents are also responsible for eliciting important defense reflexes that protect the lung and body from potential health-hazardous effects of airborne particulates and chemical irritants. This article reviews the morphology, transduction properties, reflex functions, and respiratory sensations of these receptors, focusing primarily on recent findings derived from using new technologies such as neural immunochemistry, isolated airway-nerve preparation, cultured airway neurons, patch-clamp electrophysiology, transgenic mice, and other cellular and molecular approaches. Studies of the signal transduction of mechanosensitive afferents have revealed a new concept of sensory unit and cellular mechanism of activation, and identified additional types of sensory receptors in the lung. Chemosensitive properties of these lung afferents are further characterized by the expression of specific ligand-gated ion channels on nerve terminals, ganglion origin, and responses to the action of various inflammatory cells, mediators, and cytokines during acute and chronic airway inflammation and injuries. Increasing interest and extensive investigations have been focused on uncovering the mechanisms underlying hypersensitivity of these airway afferents, and their role in the manifestation of various symptoms under pathophysiological conditions. Several important and challenging questions regarding these sensory nerves are discussed. Searching for these answers will be a critical step in developing the translational research and effective treatments of airway diseases.

Therapeutic potential of traditional chinese medicine on inflammatory diseases

Increased oxidative stress induces inflammation to several tissues/organs leading to cell death and long-term injury. Traditional Chinese Medicine (TCM) with antioxidant, anti-inflammatory, anti-apoptotic, and autophagic regulatory functions has been widely used as preventive or therapeutic strategy in modern medicine. Oxidative stress and inflammation have been widely reported to contribute to cigarette smoke-induced lung inflammation, hepatotoxicity, or sympathetic activation-induced liver inflammation, lipopolysaccharide-induced renal inflammation, and substance P-mediated neurogenic hyperactive bladder based on clinical findings. In this review, we introduce several evidences for TCM treatment including Monascus adlay (MA) produced by inoculating adlay (Cois lachrymal-jobi L. var. ma-yuen Stapf) with Monascus purpureus on lung injury, Amla (Emblica officinalis Gaertn. of Euphorbiaceae family) on hepatotoxin-induced liver inflammation, Virgate Wormwood Decoction (Yīn Chén Hāo tāng) and its active component genipin on sympathetic activation–induced liver inflammation, and green tea extract and its active components, catechins, or a modified TCM formula Five Stranguries Powder (Wǔ Lén Sǎn) plus Crataegi Fructus (Shān Zhā) on hyperactive bladder. The pathophysiologic and molecular mechanisms of TCM on ameliorating inflammatory diseases are discussed in the review.

Formaldehyde inhalation reduces respiratory mechanics in a rat model with allergic lung inflammation by altering the nitric oxide/cyclooxygenase-derived products relationship

Bronchial hyperresponsiveness is a hallmark of asthma and many factors modulate bronchoconstriction episodes. A potential correlation of formaldehyde (FA) inhalation and asthma has been observed; however, the exact role of FA remains controversial. We investigated the effects of FA inhalation on Ovalbumin (OVA) sensitisation using a parameter of respiratory mechanics. The involvement of nitric oxide (NO) and cyclooxygenase-derived products were also evaluated. The rats were submitted, or not, to FA inhalation (1%, 90 min/day, 3 days) and were OVA-sensitised and challenged 14 days later. Our data showed that previous FA exposure in allergic rats reduced bronchial responsiveness, respiratory resistance (Rrs) and elastance (Ers) to methacholine. FA exposure in allergic rats also increased the iNOS gene expression and reduced COX-1. L-NAME treatment exacerbated the bronchial hyporesponsiveness and did not modify the Ers and Rrs, while Indomethacin partially reversed all of the parameters studied. The L-NAME and Indomethacin treatments reduced leukotriene B₄ levels while they increased thromboxane B₂ and prostaglandin E₂. In conclusion, FA exposure prior to OVA sensitisation reduces the respiratory mechanics and the interaction of NO and PGE₂ may be representing a compensatory mechanism in order to protect the lung from bronchoconstriction effects.

Bronchoconstriction induced by increasing airway temperature in ovalbumin-sensitized rats: role of tachykinins

This study was carried out to determine the effect of allergic inflammation on the airway response to increasing airway temperature. Our results showed the following: 1) In Brown-Norway rats actively sensitized by ovalbumin (Ova), isocapnic hyperventilation with humidified warm air (HWA) for 2 min raised tracheal temperature (Ttr) from 33.4 ± 0.6°C to 40.6 ± 0.1°C, which induced an immediate and sustained (>10 min) increase in total pulmonary resistance (Rl) from 0.128 ± 0.004 to 0.212 ± 0.013 cmH2O·ml(-1)·s (n = 6, P < 0.01). In sharp contrast, the HWA challenge caused the same increase in Ttr but did not generate any increase in Rl in control rats. 2) The increase in Rl in sensitized rats was reproducible when the same HWA challenge was repeated 60-90 min later. 3) This bronchoconstrictive effect was temperature dependent: a slightly smaller increase in peak Ttr (39.6 ± 0.2°C) generated a significant but smaller increase in Rl in sensitized rats. 4) The HWA-induced bronchoconstriction was not generated by the humidity delivered by the HWA challenge alone, because the same water content delivered by saline aerosol at room temperature had no effect. 5) The HWA-evoked increase in Rl in sensitized rats was not blocked by atropine but was completely prevented by pretreatment either with a combination of neurokinin (NK)-1 and NK-2 antagonists or with formoterol, a β2 agonist, before the HWA challenge. This study showed that increasing airway temperature evoked a pronounced and reversible increase in airway resistance in sensitized rats and that tachykinins released from the vagal bronchopulmonary C-fiber endings were primarily responsible.

Neurogenic airway microvascular leakage induced by toluene inhalation in rats

Toluene is a representative airborne occupational and domestic pollutant that causes eye and respiratory tract irritation. We investigated whether a single inhalation of toluene elicits microvascular leakage in the rat airway. We also evaluated the effects of CP-99,994, a tachykinin NK(1) receptor antagonist, and ketotifen, a histamine H1 receptor antagonist with mast cell-stabilizing properties, on the airway response. The content of Evans blue dye that extravasated into the tissues was measured as an index of plasma leakage. Toluene (18-450 ppm, 10 min) concentration-dependently induced dye leakage into the trachea and main bronchi of anesthetized and mechanically ventilated rats. Toluene at concentrations of ≥ 50 and ≥ 30 ppm caused significant responses in the trachea and main bronchi, respectively, which both peaked after exposure to 135 ppm toluene for 10 min. This response was abolished by CP-99,994 (5 mg/kg i.v.), but not by ketotifen (1mg/kg i.v.). Nebulized phosphoramidon (1 mM, 1 min), a neutral endopeptidase 24.11 inhibitor, significantly enhanced the response induced by toluene (135 ppm, 10 min) compared with nebulized 0.9% saline (1 min). These results show that toluene can rapidly increase airway plasma leakage that is predominantly mediated by tachykinins endogenously released from airway sensory nerves. However, mast cell activation might not be important in this airway response.

Vagal afferents contribute to exacerbated airway responses following ozone and allergen challenge

Brown-Norway rats (n=113) sensitized and challenged with nDer f 1 allergen were used to examine the contribution of lung sensory nerves to ozone (O(3)) exacerbation of asthma. Prior to their third challenge rats inhaled 1.0ppm O(3) for 8h. There were three groups: (1) control; (2) vagus perineural capsaicin treatment (PCT) with or without hexamethonium; and (3) vagotomy. O(3) inhalation resulted in a significant increase in lung resistance (R(L)) and an exaggerated response to subsequent allergen challenge. PCT abolished the O(3)-induced increase in R(L) and significantly reduced the increase in R(L) induced by a subsequent allergen challenge, while hexamethonium treatment reestablished bronchoconstriction induced by allergen challenge. Vagotomy resulted in a significant increase in the bronchoconstriction induced by O(3) inhalation and subsequent challenge with allergen. In this model of O(3) exacerbation of asthma, vagal C-fibers initiate reflex bronchoconstriction, vagal myelinated fibers initiate reflex bronchodilation, and mediators released within the airway initiate bronchoconstriction.

Sialic acid reduces acute endotoxemia-induced liver dysfunction in the rat

Endotoxemia caused by LPS is a life-threatening and inflammatory condition contributing to multiple organ failure. Viruses or bacteria require sialic acid (SA) for target-cell binding. We suggest that exogenous SA through masking or mediating the binding of LPS to the target cells may attenuate LPS-induced liver dysfunction and cecal ligation and puncture-induced shock. We found that SA can directly scavenge O2-, H2O2, and NO activity by a chemiluminescence analyzer and bind to LPS with high affinity using surface plasmon resonance. Intravenous SA significantly increased plasma SA concentration within 4 h. We then assessed the potential effect of SA on LPS-induced acute endotoxemia in the rat. Intravenous LPS (10-50 mg/kg) dose-dependently increased plasma endotoxin and reactive oxygen species in the blood, bile, and liver and increased plasma alanine aminotransferase and aspartate aminotransferase levels as well as TNF-alpha, monocyte chemoattractant protein 1, tissue inhibitor of metalloproteinase 1, IL-1beta, and IL-6 levels in the rats. Thirty minutes after LPS stimulation, SA decreased LPS-enhanced endotoxin level, oxidative stress, alanine aminotransferase and aspartate aminotransferase levels, and cytokine concentration and ameliorated histopathologic alteration in the liver. We found that SA increased LPS-depressed Mn-superoxide dismutase, CuZn-superoxide dismutase, and heat shock protein 70 and decreased LPS-enhanced iNOS and proapoptotic Bax protein expression in the liver by Western blot. Sialic acid was given after treatment to rats subjected to cecal ligation and puncture, and the hypotensive effect was blunted for 6 h. In conclusion, SA treatment can counteract LPS-enhanced acute endotoxemia and oxidative injury via a direct scavenging reactive oxygen species activity and neutralization potential.

Effective prevention and treatment of Helicobacter pylori infection using a combination of catechins and sialic acid in AGS cells and BALB/c mice

The increasing emergence of Helicobacter pylori strains resistant to antibiotics may cause unsuccessful treatment. An alternative agent or mixture with anti-H. pylori effect is urgently required to reduce H. pylori infection. We explored the preventive and therapeutic potential of a combination of catechins and sialic acid on H. pylori-infected human gastric cells in vitro and in mice in vivo. We evaluated the anti-H. pylori activity of catechins and/or sialic acid using the agar dilution and checkerboard methods. The effect of catechins and/or sialic acid on H. pylori infection-induced oxidative stress and apoptosis/autophagy in cell culture was explored using an ultrasensitive chemiluminescence analyzer, immunocytochemistry, and Western blotting. Specific pathogen-free BALB/c mice were divided into uninfected control, infected control, pretreated, and post-treated groups. The effects of catechins/sialic acid were determined by histology and immunocytochemistry. The combination of catechins and sialic acid showed synergistic or additive anti-H. pylori activity and significantly reduced inducible nitric oxide synthase expression and Bax/Bcl-2-mediated apoptosis but enhanced Beclin-1-mediated autophagy. All mice infected with H. pylori displayed gastritis and accumulation of 3-nitrotyrosine and 4-hydroxynonenal. Pretreatment with catechins/sialic acid completely prevented H. pylori infection and resulted in normal histology. Post-treatment with catechins/sialic acid decreased the bacterial load and gastritis score and eradicated up to 60% of H. pylori infections in a dose-dependent manner. This is the first demonstration to our knowledge of a nonprobiotic, nonantibiotic treatment that is 100% effective in preventing and has promising possibilities for treating H. pylori infection. Further studies are needed to confirm this result in humans.

Combination of Wu Lin San and Shan Zha ameliorates substance P-induced hyperactive bladder via the inhibition of neutrophil NADPH oxidase activity

Substance P (SP) via neurokinin type 1 receptor activates leukocytes to produce burst release of reactive oxygen species (ROS) and increases leukocytes adhesion to the vessels in the inflamed bladder. Activation of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity may contribute to the neutrophil ROS production. We explored the therapeutic effect of traditional Chinese formula for urinary dysfunction, Wu Lin San (WLS), and a modified formula WLS plus Shan Zha (WLSSZ) on SP-induced bladder hyperactivity. We evaluated WLS, Shan Zha, and WLSSZ effect on neutrophils NADPH oxidase activity in SP-stimulated neutrophils in vitro, and isovolumetric cystometrogram and ROS activity in vivo in anesthetized rat bladder with SP stimulation. Our results showed that WLS, Shan Zha, and WLSSZ inhibited SP-induced NADPH oxidase activity in an order WLSSZ>Shan Zha>WLS. Exogenous SP enhanced systemic vasodilation, bladder hyperactivity and bladder ROS. One week of oral administration of WLS or WLSSZ significantly reduced SP-induced bladder ROS amount and leukocyte accumulation and ameliorated the hyperactive bladder response. The therapeutic action was better in WLSSZ than in WLS. Our results indicate that a modified formula Wu Lin San plus Shan Zha can potentially ameliorate SP-induced neurogenic inflammation possibly via the inhibition of leukocyte NADPH oxidase activity.

Pulmonary neutrophil recruitment and bronchial reactivity in formaldehyde-exposed rats are modulated by mast cells and differentially by neuropeptides and nitric oxide

We have used a pharmacological approach to study the mechanisms underlying the rat lung injury and the airway reactivity changes induced by inhalation of formaldehyde (FA) (1% formalin solution, 90 min once a day, 4 days). The reactivity of isolated tracheae and intrapulmonary bronchi were assessed in dose-response curves to methacholine (MCh). Local and systemic inflammatory phenomena were evaluated in terms of leukocyte countings in bronchoalveolar lavage (BAL) fluid, blood, bone marrow lavage and spleen. Whereas the tracheal reactivity to MCh did not change, a significant bronchial hyporesponsiveness (BHR) was found after FA inhalation as compared with naive rats. Also, FA exposure significantly increased the total cell numbers in BAL, in peripheral blood and in the spleen, but did not modify the counts in bone marrow. Capsaicin hindered the increase of leukocyte number recovered in BAL fluid after FA exposure. Both compound 48/80 and indomethacin were able to prevent the lung neutrophil influx after FA, but indomethacin had no effect on that of mononuclear cells. Following FA inhalation, the treatment with sodium cromoglycate (SCG), but not with the nitric oxide (NO) synthase inhibitor L-NAME, significantly reduced the total cell number in BAL. Compound 48/80, L-NAME and SCG significantly prevented BHR to MCh after FA inhalation, whereas capsaicin was inactive in this regard. On the other hand, indomethacin exacerbated BHR. These data suggest that after FA inhalation, the resulting lung leukocyte influx and BHR may involve nitric oxide, airway sensory fibers and mast cell-derived mediators. The effect of NO seemed to be largely restricted to the bronchial tonus, whereas neuropeptides appeared to be linked to the inflammatory response, therefore indicating that the mechanisms responsible for the changes of airway responsiveness caused by FA may be separate from those underlying its inflammatory lung effects.

Antiexudative Effects of Opioids and Expression of κ- and δ- Opioid Receptors during Intestinal Inflammation in Mice: Involvement of Nitric Oxide

The study evaluates the effects of kappa- (KOR), delta- (DOR), and mu-opioid receptor (MOR) agonists on the inhibition of plasma extravasation during acute and chronic intestinal inflammation in mice. The antiexudative effects of KOR and DOR agonists in animals treated with nitric oxide synthase (NOS) inhibitors and their protein levels in the gut (whole jejunum and mucosa) and spinal cord of mice with chronic intestinal inflammation were also measured. Inflammation was induced by the intragastric administration of one (acute) or two (chronic) doses of croton oil. Plasma extravasation was measured using Evans blue and protein levels by Western blot and immunoprecipitation. Plasma extravasation was significantly increased 2.7 times during chronic inflammation. The potency of the KOR agonist trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolydinyl)cyclohexyl]-benzeneazetamine (U50,488H) inhibiting plasma extravasation was enhanced 26.3 times during chronic compared with acute inflammation. [d-Pen(2),d-Pen(5)]-Enkephalin (DPDPE) (a DOR agonist) was also 11.8 times more potent during chronic inflammation, whereas the antiexudative effects of fentanyl (a MOR agonist) were not significantly altered. Receptor-specific antagonists reversed the effects. Protein levels of KOR and DOR in the whole jejunum and mucosa were significantly increased after chronic inflammation. Treatment with NOS inhibitors N(omega)-nitro-l-arginine methyl ester or l-N(6)-(1-iminoethyl)-lysine hydrochloride diminished plasma extravasation and inhibited the increased antiexudative effects of U50,488H and DPDPE during chronic intestinal inflammation. The data show that the enhanced antiexudative effects of KOR and DOR agonists could be related to an increased expression of KOR and DOR in the gut and that the release of nitric oxide may play a role augmenting the effects of opioids during chronic inflammation.

Thoracic Vagal Efferent Nerve Stimulation Evokes Substance P-Induced Early Airway Bronchonstriction and Late Proinflammatory and Oxidative Injury in the Rat Respiratory Tract

Electrical stimulation of efferent thoracic vagus nerve (TVN) evoked neurogenic inflammation in respiratory tract of atropine-treated rats by an undefined mechanism. We explored whether efferent TVN stimulation via substance P facilitates neurogenic inflammation via action of nuclear factor-kappaB (NF-kappaB) activation and reactive oxygen species (ROS) production. Our results showed that increased frequency of TVN stimulation concomitantly increased substance P-enhanced hypotension, and bronchoconstriction (increases in smooth muscle electromyographic activity and total pulmonary resistance). The enhanced SP release evoked the appearance of endothelial gap in silver-stained leaky venules, India-ink labeled extravasation, and accumulations of inflammatory cells in the respiratory tract, contributing to trachea plasma extravasation as well as increases in blood O (2)(-) and H(2)O(2) ROS amount. L-732138 (NK(1) receptor antagonist), SR-48968 (NK(2) receptor antagonist), dimethylthiourea (H(2)O(2) scavenger) or catechins (O (2)(-) and H(2)O(2) scavenger) pretreatment reduced efferent TVN stimulation-enhanced hypotension, bronchoconstriction, and plasma extravasation. Increased frequency of TVN stimulation significantly upregulated the expression of nuclear factor-kappaB (NF-kappaB) in nuclear protein and intercellular adhesion molecule-1 (ICAM-1) in total protein of the lower respiratory tract tissue. The upregulation of NF-kappaB and ICAM-1 was attenuated by NK receptor antagonist and antioxidants. In conclusion, TVN efferent stimulation increases substance P release to trigger NF-kappaB mediated ICAM-1 expression and O (2)(-) and H(2)O(2) ROS production in the respiratory tract.