Objective To examine the effects of Pseudomonas aeruginosa(PA)quorum-sensing systems on airway mucus hypersecretion．Methods Sixty Sprague-Dawley rats were intubated with a silicone tube pre-coated with PAO1(wild-type PA strain)，PAO1-JP2(quorum-sensing-mutant strain)or saline in the bronchus．After 28 days，the mRNA and protein expression of MUC5AC in the rats’bronchial epithelia were detected by RT-PCR，alcian blue／periodic acid—Schif(AB／PAS)staining and enzyme linked immunosorbent assay(ELISA)．Results In the PAO1 group，bronchiolar epithelium goblet cells by AB／PAS staining was significantly more than those in the PAO1-JP2 and control groups(both Plt;0．05)．The expression level of MUC5AC mRNA in the PAO1 group was significantly higher than those in the PAO1-JP2 and control groups(both P lt;0．05)．The ELISA showed that the concentration of MUC5AC protein in bronchoalveolar lavage fluid(BALF)in the PAO1 group was much higher than that in the PAO1-JP2 group(P lt;0．05)．Conclusion PA quorum-sensing system plays an important role in airway mucus hypersecretion
Objective To investigate the effects of extracts of Pinellia ( EP) on a rat model of airway mucus hypersecretion induced by LPS. Methods Thirty Wisatr rats were randomly divided into 5 groups, ie. a blank group, a model group, and three EP groups treated with different doses of EP. There were 6 rats in each group. Airway mucus hypersecretion model was established by intratracheally instillation of LPS in the model group and three EP groups. The rats in three EP groups were orally administered with EP at dosages of 10 g/kg, 30 g/kg and 60 g/kg respectively for 4 days. The expression of Mucin 5AC ( MUC5AC) protein in airway was assayed by immunohistochemistry. The mRNA expressions of MUC5AC and Aquaporin-5( AQP-5) in lung tissue were detected by RT-PCR. ELISA technique was performed to detect TNF-αin bronchoalveolar lavage fluid( BALF) . Results LPS significantly stimulated the mRNA and protein expression of MUC5AC in lung and TNF-αlevel in BALF, and inhibited the expression of AQP-5 mRNA in lung. The EP at dosages of 10 g / kg and 30 g/ kg had little effect on mucus hypersecretion. While 60 g/kg of EP could significantly inhibited the expression of MUC5AC, and decreased the release of TNF-α in BALF. The AQP-5 mRNA was also up-regulated by 60 g /kg of EP. The expression of MUC5AC mRNA was positively correlated with level of TNF-α( r = 0. 948, P lt;0. 05) ; AQP-5 mRNA was negatively correlated with MUC5AC mRNA and TNF-α( r = - 0. 955, P lt; 0. 05; r = - 0. 909, P lt; 0. 05) . Conclusion EP ( 60 g/ kg) can significantly attenuated airway mucus hypersecretion in rats.
Objective To explore the effect of leukotriene receptor antagonist montelukast on physicochemical property of sputum and airway mucus hypersecretion in patients with acute exacerbation of bronchiectasis. Methods Eighty-four inpatients with acute exacerbation of bronchiectasis were randomly divided into a control group and an experiment group, with 42 cases in each group. The control group received conventional therapy and the experiment group took orally montelukast 10 mg before sleep every day based on conventional therapy for two weeks. At admission and 15 days after admission, the amount in 24 hours, dry/wet weight ratio and viscosity of sputum were observed while the levels of neutrophil elastase (NE) and mucin MUC5ac in sputum were determined by ELISA. The pulmonary ventilation function, airway resistance and blood gas analysis were also measured. Results The sputum amount in 24 hours, dry/wet weight ratio and viscosity of sputum, NE and MUC5ac of sputum, pulmonary ventilation function, blood gas analysis and airway resistance were declined or improved remarkably after treatment compared with before treatment in two groups (P<0.05). Meanwhile, the sputum amount in 24 hours [(5.62±1.83) g vs. (7.53±2.32) g], NE [(3.85±0.97) μg/ml vs. (4.54±1.03) μg/ml], MUC5ac [(0.65±0.21) μg/ml vs. (0.82± 0.29) μg/ml] and the airway resistance [(119.16±11.76)% vs. (128.37±12.08)%] were declined remarkably in the experiment group compare with the control group after treatment (all P<0.05). The viscosity of sputum between the two groups after treatment showed no significant difference. Conclusion In patients with acute exacerbation of bronchiectasis, montelukast can reduce amount of sputum and airway resistance, reduce expression of mucin MUC5ac through down-regulation of NE, thus inhibit airway mucus hypersecretion.
ObjectiveTo explore the effects of elafin on the regulation of mucin5AC (MUC5AC) in airway epithelial cells.MethodsAfter cultivating epithelial cells in vitro, cells were stimulated by cigarette smoke extract (CSE) and lipopolysaccharide (LPS), the intracellular MUC5AC production and extracellular secretion were assayed by immunofluorescence and ELISA, respectively.ResultsThe level of MUC5AC protein was obviously increased in the LPS stimulation group [(0.785±0.005) μg/ml vs. (0.232±0.004) μg/ml] and the CSE stimulation group [(0.803±0.005) μg/ml vs. (0.255±0.003) μg/ml] than those in the blank control groups (both P<0.01). When pretreated with elafin then stimulated by LPS and CSE, the MUC5AC productions were evidently decreased than those in the single LPS and CSE stimulation groups [(0.363±0.003) μg/ml and (0.406±0.006) μg/ml, bothP<0.01]. As compared with the blank control groups, the MUC5AC protein secretion were significantly decreased after stimulated with single elafin [(0.176±0.002) μg/ml and (0.193±0.004) μg/ml, bothP<0.05].ConclusionElafin may inhibit MUC5AC hypersecretion by blocking MUC5AC production and secretion.
Objective To investigate whether interleukin-1 receptor associated kinase (IRAK) participates the airway mucus hypersecretion induced by lipopolysaccharide (LPS). Methods The expression of Toll-like receptor (TLR)-4 or IRAK was down regulated by the transfection of specific small interfering RNA (siRNA). The transcription level of mucin 5AC (MUC5AC) mRNA as well as the secretion level of MUC5AC protein were judged by reverse transcription polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA), respectively. The activity of signaling molecules involved in TLR-4 associated pathway, such as the phosphorylated IRAK, nuclear translocation of NF-κB p65, was analyzed by Western blot. Results The level of intracellular phosphorylated IRAK was increased by stimulation of LPS in BEAS-2B cells. However, down-regulation of TLR-4 by siRNA could partially attenuate the additional phosphorylation of IRAK induced by LPS (P<0.05). LPS elicited a nuclear translocation of NF-κB p65 in BEAS-2B cells, which could be partially blocked by the down-regulation of TLR-4 or IRAK. With RT-PCR, an increased expression level of MUC5AC mRNA was discovered in wild-type BEAS-2B cells (0.82±0.09) than TLR-4 defect cells (0.36±0.05), IRAK defect cells (0.48±0.05) and IRAK inhibitor pretreated cells (0.57±0.07) (all P<0.05). Meanwhile, according to ELISA, an increased secretion level of MUC5AC protein was recorded in wild-type BEAS-2B cells [(0.76±0.09) μg/L] than TLR-4 defect cells [(0.33±0.04) μg/L], IRAK defect cells [(0.42±0.05) μg/L] and IRAK inhibitor pretreated cells [(0.51±0.06) μg/L] (all P<0.05). Conclusion As an crucial regulator of TLR dependent signaling pathway, IRAK may participate the airway mucus over-synthesis induced by LPS.