Aggravated inflammation and increased expression of cysteinyl leukotriene receptors in the brain after focal cerebral ischemia in AQP4-deficient mice.

OBJECTIVE: Aquaporin-4 (AQP4), the main water channel protein in the brain, plays a critical role in water homeostasis and brain edema. Here, we investigated its role in the inflammatory responses after focal cerebral ischemia. METHODS: In AQP4-knockout (KO) and wild-type mice, focal cerebral ischemia was induced by 30 min of middle cerebral arterial occlusion (MCAO). Ischemic neuronal injury and cellular inflammatory responses, as well as the expression and localization of cysteinyl leukotriene CysLT(2) and CysLT(1) receptors, were determined at 24 and 72 h after MCAO. RESULTS: AQP4-KO mice showed more neuronal loss, more severe microglial activation and neutrophil infiltration, but less astrocyte proliferation in the brain after MCAO than wild-type mice. In addition, the protein levels of both CysLT(1) and CysLT(2) receptors were up-regulated in the ischemic brain, and the up-regulation was more pronounced in AQP4-KO mice. The CysLT(1) and CysLT(2) receptors were primarily localized in neurons, microglia and neutrophils; those localized in microglia and neutrophils were enhanced in AQP4-KO mice. CONCLUSION: AQP4 may play an inhibitory role in postischemic inflammation.

Aquaporin-4 deficiency attenuates acute lesions but aggravates delayed lesions and microgliosis after cryoinjury to mouse brain.

OBJECTIVE: To determine whether aquaporin-4 (AQP4) regulates acute lesions, delayed lesions, and the associated microglial activation after cryoinjury to the brain. METHODS: Brain cryoinjury was applied to AQP4 knockout (KO) and wild-type mice. At 24 h and on days 7 and 14 after cryoinjury, lesion volume, neuronal loss, and densities of microglia and astrocytes were determined, and their changes were compared between AQP4 KO and wild-type mice. RESULTS: Lesion volume and neuronal loss in AQP4 KO mice were milder at 24 h following cryoinjury, but worsened on days 7 and 14, compared to those in wild-type mice. Besides, microglial density increased more, and astrocyte proliferation and glial scar formation were attenuated on days 7 and 14 in AQP4 KO mice. CONCLUSION: AQP4 deficiency ameliorates acute lesions, but worsens delayed lesions, perhaps due to the microgliosis in the late phase.

[Deficiency of water channel AQP4 aggravates NMDA-induced brain injury in mice].

OBJECTIVE: To evaluate the role of water channel AQP4 in NMDA-induced brain injury in mice. METHODS: In AQP4 gene knockout (AQP4(-/-)) mice, brain injury was induced by microinjection of NMDA into the cortex. The injured area was determined by toluidine blue staining, degenerated neurons were detected by Fluro-Jade B staining, and increased blood-brain barrier (BBB) permeability was evaluated by IgG immunostaining. RESULT: Compared with wild-type mice, AQP4(-/-) mice exhibited increased cortical lesion area, aggravated neuron degeneration, and increased BBB disruption after NMDA microinjection. CONCLUSION: AQP4 may play a protective role in NMDA-induced brain injury in mice.

[Rotenone-induced changes of cysteinyl leukotriene receptor 1 expression in BV2 microglial cells].

OBJECTIVE: To prepare and identify a polyclonal antibody (pAb) against (mouse) cysteinyl leukotriene receptor 1 (CysLT(1)) and to investigate the changes of CysLT(1) receptor expression in BV2 microglial cells after rotenone treatment. METHODS: Rabbits were immunized with KLH-coupled CysLT(1) peptide to prepare the pAb. The titer of the pAb in rabbit plasma was detected by ELISA method, and the specificity of the pAb was tested by antigen blockade. After BV2 cells were treated with rotenone (0.01-1 µmol/L) for 24 h, the expression of CysLT(1) was determined by immunostaining, Western blotting and RT-PCR. RESULT: The pAb showed a titer of 1/32728, and was not cross-reacted with antigens of CysLT(2) receptor and GPR17. Immunostaining, Western blotting and RT-PCR analysis showed the expression of CysLT(1) receptor in BV2 microglia. Rotenone at 1µmol/L significantly induced an increased expression of CysLT(1) receptor. CONCLUSION: The prepared CysLT(1) receptor polyclonal antibody has a high titer and high specificity to meet testing requirements of Western blotting and immunostaining; CysLT(1) is associated with rotenone-induced injury of BV2 microglial cells.

Involvement of type II pneumocytes in the pathogenesis of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality, but the cellular and molecular mechanisms are still not fully understood. Type II pneumocytes are identified as the synthesizing cells of the alveolar surfactant, which has important properties in maintaining alveolar and airway stability. Lung surfactant can reduce the surface tension and prevent alveolar collapse and the airway walls collapse. Pulmonary surfactant components play important roles in normal lung function and inflammation in the lung. Surfactant has furthermore been shown to modulate the process of innate host defense, including suppression of cytokine secretion and transcription factor activation, in the inflammatory network of COPD. Abnormalities of lung surfactant might be one of the mechanisms leading to increased airway resistance in COPD. The increased expression of Granzyme A and B was found in lung tissues of patients with COPD and type II pneumocytes was proposed to be involved in the pathogenesis of COPD. These novel findings provide new sights into the role of the type II pneumocytes in the pathogenesis of COPD.

Zl-n-91, a selective phosphodiesterase 4 inhibitor, suppresses inflammatory response in a COPD-like rat model.

Chronic obstructive pulmonary disease (COPD) is defined as a disease state characterized by poorly reversible airflow limitation induced by cigarette smoking and/or other noxious particle and gases. Phosphodiesterase (PDE) 4 inhibitors are known to elevated cAMP concentrations in inflammatory cells, leading to inhibition of inflammatory response, relaxation of smooth muscle in the airway, and modulation of sensory nerves in the lung as well. To investigate whether Zl-n-91, a new selective PDE4 inhibitor, could decrease inflammation and improve lung function in a COPD-like rat model, male Sprague-Dawley rats are used to challenge with lipopolysaccharide (LPS) and cigarette smoking (CS) exposure to induce COPD-like animal model. Administration of Zl-n-91 at different dosages results in decreases of inflammatory cell in bronchoalveolar lavage fluid (BALF) as compared with vehicle treatment. Zl-n-91 at 0.03, 0.3 or 3mg/kg not only dose-dependently inhibited PDE4 activity, but also decreased MMP-9 level in lungs and improved dynamic compliance (C(dyn)) as compared with vehicle treatment. Therefore, Zl-n-91 could inhibit inflammatory responses in rats after cigarette smoking exposure and LPS challenge, and it could be of some therapeutic potential as an alternative medicine in treatment of pulmonary diseases such as COPD.

[Preparation and identification of polyclonal antibody against cysteinyl leukotriene receptor 2].

OBJECTIVE: To prepare and identify a polyclonal antibody against cysteinyl leukotriene receptor (CysLT(2)receptor). METHODS: Rabbits were immunized with KLH-coupled CysLT(2) receptor peptide to prepare the polyclonal antibody (pAb). The titer of the pAb in rabbit plasma was detected by indirect ELISA, and the specificity of the pAb was tested by antigen blockade. The tissue distribution of CysLT(2) receptor was detected by Western blot and immunohistochemistry with the prepared pAb. RESULT: The pAb showed a titer higher than 1/1047296, and was specific to CysLT(2) receptor, without cross-reaction with the antigens of CysLT(1) receptor and GPR17. A higher expression of CysLT(2) receptor in kidney, brain and lung of rats and mice was detected by Western blot analysis using the prepared pAb. The molecular weight of CysLT(2) receptor protein was about 40 kD. Immunohistochemical examination showed that CysLT(2) receptor was expressed mainly in the neuron, and partly in astrocytes in rat brain. CONCLUSION: The prepared CysLT(2) receptor pAb has high sensitivity and specificity, and can be used in Western blot and immunohistochemistry.

[Preparation and identification of a polyclonal antibody against novel cysteinyl leukotriene receptor GPR17].

OBJECTIVE: To prepare and identify a polyclonal antibody (pAb) against GPR17, a novel cysteinyl leukotriene receptor. METHODS: Rabbits were immunized with KLH-coupled GPR17 peptide to prepare the pAb. The titer of the pAb in rabbit plasma was detected by indirect ELISA, and the specificity of the pAb was tested by antigen blockade. GPR17 tissue distribution was detected by Western blot with the pAb. RESULTS: The pAb showed a titer as high as 1:16 364,and was not cross-reacted with the antigens of CysLT(1) and CysLT(2) receptors. A higher expression of GPR17 in the rat brain and heart was detected using the newly prepared pAb. The molecular weigh of GPR17 protein was about 43 kD. CONCLUSION: The prepared GPR17 pAb has high sensitivity and specificity,and can be used in Western blot for detecting GPR17.

[Effect of QTY06 on lipopolysaccharide-induced chronic airway inflammation and MUC5ac secretion in rats].

OBJECTIVE: To investigate the effect of synthetic drug QTY06 on chronic airway inflammation and mucoprotein expression induced by intratracheal (i.t) instillation of lipopolysaccharide (LPS). METHODS: Chronic airway inflammation was induced by i.t instillation of LPS in rats. Phospholipids content and the number of leucocytes in bronchoalveolar lavage fluid (BALF), pathological and immunochemical changes were examined 3 weeks after LPS instillation. The effect of QTY06 on chronic airway inflammation was observed. RESULT: After treatment with QTY06, phospholipids in BALF was significantly increased, and the percentages of neutrophils and lymphocytes were decreased as well as the total number of leucocytes. Compared with the model group, pathological examination showed that tracheitis, bronchitis and pulmonary interstitial inflammation in QTY06 groups were significantly attenuated; epithelial damage was alleviated, infiltration of inflammatory cells reduced and the number of goblet cells decreased. QTY06 significantly decreased MUC5ac expression in trachea and bronchiole epithelium, and reduced the optical density and mucins area (%) as detected by image analysis in rats with chronic airway inflammation. CONCLUSION: QTY06 can reduce and inhibit the chronic airway inflammation induced by LPS in rats, and increase the content of phospholipids in pulmonary surfactant and inhibit the hypersecretion of airway mucins.

[Effect of Spearmint oil on inflammation, oxidative alteration and Nrf2 expression in lung tissue of COPD rats].

OBJECTIVE: To investigate the effect of Spearmint oil on inflammation, oxidative alteration and Nrf2 expression in rats with chronic obstructive pulmonary disease(COPD). METHODS: COPD model was induced by intratracheal instillation of Klebsiella pneumonia and lipopolysaccharide (LPS) for 12 weeks in rats, and COPD rats were treated with Spearmint oil for 3 weeks. After COPD was induced, the pathological changes, changes in leucocyte number in blood and bronchoalveolar lavage fluid (BALF), MDA in lung homogenate and Nrf2 expression were observed. The effects of Spearmint oil on these changes were determined. RESULT: Spearmint oil 100 mg*kg(-1)significantly reduced leucocyte numbers in BALF, and attenuated bronchiolitis, pulmonary interstitial inflammation and inflammation cell infiltration. Spearmint oil 30-300 mg*kg(-1)decreased the destruction of pulmonary alveolus and the thickness of bronchioles walls, and inhibited goblet cell proliferation. Spearmint oil significantly reduced MDA in lung homogenate, and decreased the expression of Nrf2 protein in lung tissues. CONCLUSION: Spearmint oil has protective effect on lung injury in COPD rats, since it improves pulmonary inflammation,oxidative alteration, and enhances Nrf2 protein expression.