Maximal forced expiratory maneuver to measure airway obstruction in anesthetized guinea pigs

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.

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.