Bronchoconstriction and eosinophil recruitment in guinea pig lungs after platelet activating factor administration

The effect of atorvastatin on lung histopathology in a murine model of chronic asthma

INTRODUCTION

Atorvastatin is a statin group medicine that reduces the level of serum cholesterol; thus it is used to treat hypercholesterolaemia. Independent of the cholesterol-lowering property of statins they also have anti-inflammatory and immunomodulating effects. This study aimed to investigate the effect of atorvastatin on histological changes in the lungs in a murine model of chronic asthma.

MATERIALS AND METHODS

Twenty-eight BALB/c mice in Group I, II, III and IV were divided into four groups. All the mice except the control group (Group I) were sensitised with ovalbumin. Intraperitoneal injection with saline, atorvastatin (10mg/kg), dexametazon (1mg/kg) was administered to Group II, Group III, and Group IV respectively for five consecutive days. Mice were sacrificed 24h after the last drug administration. All the histological properties of lung tissue samples from all groups were evaluated with light and electron microscopy. In addition, IL-4 and IL-5 levels of the lung tissue were measured.

RESULTS

When Group II and Group III (atorvastatin) were compared, thicknesses of basement membrane and subepithelial smooth muscle layer, height of epithelium, number of mast and goblet cells were significantly lower in Group III. In comparing Group III (atorvastatin) and Group IV (dexamethasone), all the improvements in histological parameters were similar. In addition, the IL-4 and IL-5 levels of the lung tissue were significantly lower in atorvastatin group (Group III) compared to placebo-treated group.

CONCLUSION

Atorvastatin had a beneficial effect on histological changes in a chronic murine model of asthma.

The effect of rupatadine on lung histopathology in a murine model of chronic asthma

INTRODUCTION

Rupatadine is a new second-generation antihistamine with H(1) receptor antagonist activity and platelet-activating factor antagonist properties. This study aimed to investigate the effect of rupatadine on histologic changes in the lungs in a murine model of chronic asthma.

MATERIALS AND METHODS

Thirty-five BALB/c mice were divided into five groups of seven mice each: group I (control), group II (placebo [saline]), group III (dexamethasone 1 mg · kg(-1)·d(-1)), group IV (rupatadine 3 mg·kg(-1) d(-1)), and group V (rupatadine 30 mg·kg(-1)·d(-1)). Groups II through V were sensitized and challenged with ovalbumin and treated once per day via the oral route (gavage). Animals were sacrificed 24 h after the last treatment was administered. Airway histopathology was evaluated using light and electron microscopy in all groups.

RESULTS

There were no significant differences observed in any of the histologic parameters between groups II and IV. There were significantly thinner basement membrane, subepithelial smooth muscle layer, and epithelia were significantly thinner in group V than in group II (p < .05). There were no statistically significant differences in the thicknesses of the basement membrane, subepithelial smooth muscle layer and epithelia between groups III and V.

CONCLUSION

Rupatadine had a beneficial effect on histologic changes in a chronic murine model of asthma.

Induction of inflammatory cell accumulation by TM-N49 and promutoxin, two novel phospholipase A(2)

Local inflammation is a prominent characteristic of snakebite wound. Snake venom phospholipase A(2)s (PLA(2)s) are one of the main components which contribute to accumulation of inflammatory cells. We have isolated TM-N49 and promutoxin from Protobothrops mucrosquamatus venom and investigated their ability in induction of cell accumulation by using an in vivo mouse model. The results showed that both TM-N49 and promutoxin are potent stimuli for induction of neutrophil, lymphocyte, macrophage and eosinophil accumulation in the mouse peritoneum. The TM-N49- and promutoxin-induced inflammatory cell accumulation was inhibited by pretreatment of animals with cyproheptadine, terfenadine and Ginkgolide B, indicating that histamine and PAF is likely to contribute to the cells accumulation. Pre-injection of antibodies against adhesion molecules ICAM-1, CD18, CD11a and L-selectin showed that ICAM-1 is a key adhesion molecule of TM-N49- and promutoxin-induced lymphocyte, macrophage and eosinophil accumulation; CD18 and CD11a plays an important role in the migration of neutrophils, eosinophils and macrophages; and L-selectin is involved in the neutrophil and eosinophil accumulation. In conclusion, induction of inflammatory cell accumulation by TM-N49 and promutoxin confirms that group II PLA(2)s is pivotal stimulus for cell infiltration, through which they participate in the formation of snakebite inflammation.

Platelet activating factor as a mediator and therapeutic approach in bronchial asthma

Platelet activating factor (PAF) is a potent phospholipid mediator involved in anaphylaxis and chronic inflammatory disorders, including bronchial asthma. PAF is able to act both, directly as a chemotactic factor and indirectly through the release of other inflammatory agents. Apart from its known potent ability to activate platelets, PAF influences other immune and inflammatory cells function involved in asthma, which may be of importance in the pathogenesis of the disease. In addition, PAF administration can mimic some of abnormalities observed in asthma, including bronchoconstriction, bronchial hyper responsiveness, and gas exchange impairment, which may be mediated by leukotrienes acting as secondary mediators of some PAF effects. Therefore, there has been an extensive interest in the role of PAF in human asthma and major efforts have been continued to discover drugs acting thorough inhibition of PAF effects in the disease. Surprisingly, PAF receptor antagonists have not clearly proven their clinical benefits. It may appear that the combined blockage of PAF effects and other mediators involved in asthma is a way to improve clinical efficacy and also an interesting approach to control inflammation in the disease. This review will focus on two main issues: the role of PAF and PAF antagonists in asthma.

In vivo PAF-induced airway eosinophil accumulation reduces bronchial responsiveness to inhaled histamine

Chronic eosinophilic bronchitis and bronchial hyperresponsiveness have been considered to be the fundamental features of bronchial asthma. However, the role of airway eosinophils in bronchial responsiveness in vivo has not been fully discussed. The aim of this study was to investigate the direct effect of airway eosinophil accumulation on bronchial responsiveness in vivo. Guinea pigs were transnasally treated with platelet activating factor (PAF) or vehicle twice a week for a total of 3 weeks. Anesthetized guinea pigs were surgically cannulated and artificially ventilated 48 h after the last administration of PAF or vehicle. Ten minutes after the installation of artificial ventilation, ascending doses of histamine were inhaled. In a subsequent study, selective inhibitors of diamine oxidase and histamine N-methyltransferase were intravenously administered before the histamine inhalation in the PAF-treated animals. Next study was conducted 20 min after treatment with indomethacin in this study line. Finally, ascending doses of methacholine were inhaled in our animal model. Proportion of eosinophils and the number of nuclear segmentation in bronchoalveolar lavage fluid significantly increased in guinea pigs treated with PAF compared with vehicle and this finding was confirmed histologically. Nevertheless, bronchial responsiveness to inhaled histamine, but not methacholine, was significantly decreased by the PAF treatment. This bronchoprotective effect induced by PAF remained following aminoguanidine and histamine N-methyltransferase administration, but abolished by treatment of indomethacin. These results suggest that in vivo airway eosinophils may reduce nonspecific bronchial responsiveness through production of inhibitory or bronchoprotective prostanoids, but not through histaminase production.

Adenosine 5'-triphosphate axis in obstructive airway diseases

In recent years, significant progress has been made in our understanding of the pathophysiology behind obstructive airway diseases in general and asthma in particular; this knowledge, however, has not translated to major breakthroughs in the treatment of these disorders. Current therapeutic options are less than optimal and frequently are associated with systemic adverse effects. Recent studies indicate that endogenous purine nucleotides, adenosine 5'-triphosphate (ATP) in particular, could play a mechanistic role in obstructive airway diseases through their actions on multiple cell types relevant to these disorders, including mast cells, eosinophils, dendritic cells, and neurons. The pharmacologic modulation of ATP signal transduction in these cells represents an attractive new therapeutic target.

Pulmonary function changes and immunomodulation of cytokine expression by zafirlukast after sensitization and allergen challenge in brown Norway rats

BACKGROUND

The cysteinyl leukotrienes are known important mediators in bronchial asthma.

OBJECTIVE

Our purpose was to evaluate the effect of zafirlukast on the late-phase reaction, bronchial hyper-responsiveness (BHR) and T cell-related cytokine mRNA expression in ovalbumin (OA)-sensitized brown Norway rats (BNRs).

METHODS

Thirty BNRs were equally divided into three groups. Group I and II animals were sensitized and then provoked with OA. Zafirlukast was given intraperitoneally (i.p.) to group I animals prior to provocation. Group II animals received i.p. normal saline. Group III animals (controls) were not sensitized and breathed aerosolized saline. After OA provocation, the animals were anaesthetized. Pulmonary function tests (PFT) were performed at baseline and after varying doses of acetylcholine. Thereafter, bronchoalveolar lavage (BAL) was performed and the lungs were examined histologically. Total RNA was extracted from lung tissue and reverse transcriptase-polymerase chain reaction (RT-PCR) was performed using primers for IL-2, IL-4, IL-5, IL-6, IL-10, TNF-alpha, IFN-gamma, iNOS and beta-actin.

RESULTS

Group II OA-treated BNRs had worse PFT results, more severe bronchoconstriction in response to acetylcholine, and more severe inflammation in lung tissue than the other two groups. Group II had higher IL-2, IL-4, IL-10 and IFN-gamma cytokine levels in BAL fluid and higher IL-2, IL-4, IL-5, IL-6, IL-10, IFN-gamma, TNF-alpha and iNOS mRNA levels when compared with group I.

CONCLUSION

Zafirlukast is effective in preventing late-phase bronchoconstriction and BHR, reducing inflammatory response, and decreasing IL-2, IL-4, IL-5, IL-6, IL-10 and IFN-gamma and iNOS mRNA expression.

Maximal forced expiratory maneuver to measure airway obstruction in allergen challenged mice

Our purpose was to develop a method of using a maximal forced expiratory maneuver (MFEM) for the study of bronchoconstriction and bronchial hyperreactivity (BHR) induced in mice by ovalbumin (OA) inhalation challenge. Eight mice (group I) were sensitized and then provocated with OA. Pulmonary function testing (PFT) at baseline and after varying doses of acetylcholine challenge was performed. Eight weight-matched normal mice served as controls (group II). Pulmonary functions include MFEM, dynamic respiratory system compliance (Crs) and respiratory system resistance (Rrs). The results showed that mice treated with OA had worse PFTs than normal controls, characterized by lower MFEF 50%, FEV0.1 and Crs but higher Rrs. The OA-sensitized mice also had more severe bronchoconstriction in response to acetylcholine, characterized by greater decreases in MFEF 50%, FEV0.1 and Crs but a higher Rrs than the controls. There was a good correlation between PD20MFEF50%Ach and PD20FEV0.1Ach with PD20CrsAch and PD20RrsAch. In conclusion, the MFEM can be used to evaluate airway obstruction and BHR induced in mice by allergen challenge.

Pulmonary function changes and immunomodulation of Th 2 cytokine expression induced by aminophylline after sensitization and allergen challenge in brown Norway rats

BACKGROUND AND OBJECTIVE

Evidence has shown that aminophylline has bronchoprotective, anti-inflammatory, and immunomodulatory effects. Our purpose was to evaluate the effect of different doses of aminophylline on the late-phase reaction, bronchial hyperresponsiveness (BHR) and T cell-related cytokine mRNA expression in brown Norway rats induced by ovalbumin (OA) sensitization.

METHODS

Forty rats were equally divided into four groups. Groups I, II, and III animals were sensitized and subsequently provoked with OA. Aminophylline 25 mg/kg was given intraperitoneally to the group I animals and 5 mg/kg to group II animals. Group III animals received intraperitoneal normal saline. Group IV breathed aerosolized saline as a control. After OA provocation, the animals were anesthetized. Pulmonary function tests were performed at baseline and after varying doses of acetylcholine. Thereafter, bronchoalveolar lavage was performed and the lungs were examined histologically. Total RNA was extracted from lung tissue and reverse transcriptase-polymerase chain reaction was performed using primers for interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10, interferon-gamma, inducible nitric oxide synthase, and beta-actin.

RESULTS

Group III had worse pulmonary function tests, more severe BHR, and more severe lung inflammation, higher IL-4 and IL-10 cytokine levels in bronchoalveolar lavage fluid, and higher IL-4, IL-5, IL-6, IL-10, tumor necrosis factor-alpha and inducible nitric oxide synthase mRNA expression than the other three groups. Expression of IL-2 and interferon-gamma was significantly reduced in group III.

CONCLUSIONS

Both low and high dose aminophylline are effective in preventing late-phase bronchoconstriction, BHR, and an inflammatory response. Aminopylline decreases T helper cell 2-related cytokine mRNA expression but increases T helper cell 1-related cytokines mRNA expression.

Pulmonary function changes and increased Th-2 cytokine expression and nuclear factor kB activation in the lung after sensitization and allergen challenge in brown Norway rats

BACKGROUND

Our purpose was to evaluate the expression of Th-1 and Th-2 related cytokine mRNA and nuclear factor (NF) kB in the lung tissue of ovalbumin (OA) sensitized brown Norway rats (BNR). We also evaluated the correlation between bronchial hyperreactivity (BHR) and eosinophils with cytokine mRNA expression.

METHODS

Eight BNR (weight range 250-350 g) were sensitized by inhaled OA (group I) with a 1-week interval between and then provoked with OA 1 week later. Pulmonary function tests (PFT) were performed at baseline and 24 h after acetylcholine challenge. Eight weight-matched normal BNR served as controls (group II). All animals were anesthetized, paralyzed with gallamine, and ventilated via tracheostomy. They were given varying doses of acetylcholine (25, 50, 75, 100 microg/kg) injected through a jugular venous catheter. Five seconds after acetylcholine injections, PFTs were performed, including a maximal forced expiratory maneuver (MFEM), airway opening pressure (P(ao)) at tidal breathing and total dynamic lung compliance (C(dyn)). Bronchoalveolar lavage (BAL) was then performed with 20 ml normal saline divided into two doses. Thereafter, the lungs were removed and examined histologically. Total RNA was extracted from lung tissue samples and reverse-transcriptase polymerase chain reaction was performed using primers for mRNA of IL-4, IL-5, IL-10, interferon-gamma (IFNr) and beta-actine.

RESULTS

Group I OA treated rats had typical airway obstruction on PFTs and airway inflammation on histological examination. Ratios of IL-4, IL-5, IL-10 and inducible nitric oxide synthase (iNOS) mRNA levels to beta-actine as measured by densitometry were significantly lower in controls than in OA-sensitized rats. The IFNr mRNA to beta-actin ratio was significantly reduced in OA-sensitized rats. Group I demonstrated a band shift when compared with group II in electromobility shift assay (EMSA) for NF-kB indicating increased activation of this transcription factor.

CONCLUSION

Th-2 related cytokine mRNA was increased but Th-1 related cytokine mRNA was decreased in OA-sensitized BNR. An increased level of Th-2 related cytokine mRNA correlated with decreased airflow and inflammatory changes. These results demonstrate the value of the BNR model for studying allergic asthma at the molecular level.

Stem cell factor-induced airway hyperreactivity in allergic and normal mice

The induction of airway hyperreactivity during allergic responses involves multiple ill-defined mechanisms. Recently a role for stem cell factor (SCF) in the development of allergic eosinophilic airway inflammation has been identified. In the present study we demonstrate that SCF has a role in both the inflammatory response and airway hyperreactivity. Neutralization of SCF or examination of SCF-mutant mice, which were deficient in SCF and pulmonary mast cells, demonstrated significant alterations in the allergen-induced airway hyperreactive responses. The reduced hyperreactivity response was accompanied by a significant reduction in eosinophil accumulation. To examine the direct role of SCF on airway hyperreactivity, we administered SCF into the airways of normal mice via intratracheal injections and demonstrated a dose dependent increase in airway hyperreactivity at 4 hours that was maintained at 24 hours after administration. Instillation of SCF into SCF-deficient (mast cell deficient) mice demonstrated significantly lower increases in airway hyperreactivity compared with the littermate controls with normal mast cell numbers. These studies demonstrate that locally expressed SCF can induce changes in airway physiology via mast cell activation, verifying the role of SCF in allergic airway inflammation and hyperreactivity.