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Objective: To study the role of phosphorylation of c-Jun NH2-terminal kinase (JNK) in asthmatic airway remodeling and to explore the effect of glucocorticoids on IL-1beta, JNK and airway remodeling., Methods: Forty-eight 4 - 6 week old male SD rats were randomly divided into 4 groups with 12 rats in each group: the control group, the asthma group, the budesonide (BUD) group, and the dexamethasone (DXM) group. The asthma airway remodeling models were made by intra-peritoneal injection of ovalbumin (OVA) on days 1 and 8 and inhalation of OVA every other day for 12 weeks since day 15. The BUD group underwent inhalation of BUD 30 min before every inhalation; the DXM group received intra-peritoneal injection of DXM 30 min before every inhalation; while the control group received normal saline instead of OVA. The histopathology and ultrastructural changes of pulmonary tissues were observed by light microscope and transmission electron microscope (TEM). The total bronchial wall thickness (Wat) and the airway smooth muscle thickness (Wam) were measured by image analysis system. The concentrations of IL-1beta in serum and BALF were tested by sandwich ELISA. The protein expressions of P-JNK and P-c-Jun were detected by immunohistochemistry technique. Lung tissue extracts were analyzed for phosphorylation of JNK by Western blot. Linear correlation analysis was used to evaluate correlations between Wat and P-JNK protein (mA), Wam and P-JNK protein (mA), P-JNK protein (mA) and levels of IL-1beta in serum, P-JNK protein (mA) and levels of IL-1beta in BALF., Results: In the asthma group, HE-staining showed inflammatory cell infiltration around bronchi and mucous gland hyperplasia. TEM examination showed airway smooth muscle and collagen fiber proliferation, and widening of intercellular distance. The Wat and Wam of the asthma group were significantly higher than those of the control group, while the thickness of airway wall in the glucocorticoid intervention groups became significantly decreased. The concentrations of IL-1beta in serum and BALF of the asthma group [(81 +/- 4) ng/L, (331 +/- 15) ng/L] were significantly higher than those of the control group [(53 +/- 6) ng/L, (130 +/- 9) ng/L] (t = -8.62 and t = -24.10, both P < 0.01). Mean absorbance values (by immunohistochemistry) of P-JNK and P-c-Jun in the asthma group were significantly higher than those of the control group, and the mean absorbance values of P-JNK and P-c-Jun in the BUD and DXM groups were significantly lower than those of the asthma group, but higher than those of the control group (F = 223.59 and F = 76.53, both P < 0.01). Absorbance (by Western blot) of P-JNK in the control, asthma, BUD, and DXM groups were (1.00 +/- 0.00), (1.66 +/- 0.16), (1.18 +/- 0.12), and (1.29 +/- 0.14), respectively; that of the asthma group was significantly higher than that of the control group, while absorbance of P-JNK in the BUD and the DXM groups were significantly lower than that of the asthma group, but higher than that of the control group (F = 17.84, P < 0.05). Strong positive correlations were found between Wat or Wam and P-JNK (mA) (r = 0.700 and r = 0.769, P < 0.01, respectively, n = 48). Strong positive correlations were also found between P-JNK (mA) and concentration of IL-1beta in serum or BALF (r = 0.689 and r = 0.805, P < 0.01, respectively, n = 48)., Conclusion: Phosphorylation of JNK is closely related to asthma airway remodeling. Glucocorticoids can inhibit phosphorylation of JNK, one mechanism of which may be down-regulation of IL-beta expression.

Objective: To study role of external signal regulated kinase (ERK) and transforming growth factor beta(1) (TGF-beta1) in asthma airway remodeling and to explore the regulation of glucocorticoids on ERK, TGF-beta1, and airway remodeling., Methods: Thirty SD rats were randomly divided into 3 equal groups: control group; asthma group, undergoing intra-peritoneal injection of ovalbumin (OVA) on days 1 and 8 and inhalation of OVA every other day for 8 weeks since day 15 to establish chronic asthma models; dexamethasone (DM) intervention group, undergoing intra-peritoneal injection of DM 30 min before every inhalation instigation; and control group, receiving normal saline instead of DM. 1 - 2 hours after the last instigation the left lungs were taken out. The total bronchial wall thickness (Wat) and smooth muscle thickness (Wam) were measured by image analysis system. Phosphorylated ERK (P-ERK) was detected by immunohistochemistry. 1 - 2 hours after the last instigation blood samples were collected from the femoral artery. The concentration of transforming growth factor (TGF)-beta1 in the serum was measured by sandwich ELISA. Rat airway epithelial cells were cultured, stimulated with platelet-derived growth factor-BB (PDGF-BB, 1, 10, 25, or 50 microg/L), U0126 (specific inhibitor of phosphorylation of ERK), or budesonide (BUD). Western blotting was used to detect the P-ERK level. The level of TGF-beta1 in the cell culture supernatant was detected by sandwich ELISA., Results: The Wat and Wam of the asthma group was significantly higher than those of the control group (both P < 0.01), and the Wat and Wam of the DM group were both significantly lower than those of the asthma group (both P < 0.01). The mean optical density of P-ERK and concentration of TGF-beta1 in the serum of the asthma group were 31.1 +/- 2.2 and 28.1 +/- 7.4 microg/L respectively, both significantly higher than those of the control group (12.8 +/- 2.4 and 13.6 +/- 2.7 microg/L respectively, both P < 0.01), and the mean optical density of P-ERK and concentration of TGF-beta1 in the serum of the DM group were 18.7 +/- 3.1 and 15.0 +/- 3.2 microg/L respectively, both significantly lower than those asthma group (both P < 0.01). In the PDGF-BB (25 microg/L) stimulated cells marked phosphorylation of ERK occurred 15 min later, the level of P-ERK remained high up to 8 hour later, and the maximal activation occurred at the period of 2 h - 4 h later, 6.5 +/- 0.4 times that of the control value (P < 0.01). The phosphorylation levels of ERK depended on the concentration of PDGF-BB and the maximal level phosphorylation was detected with the concentration of PDGF-BB of 50 microg/L, which was 4.1 +/- 0.3 times that of the control value (P < 0.01). U0126 and BUD inhibited the phosphorylation of ERK in the cells stimulated by PDGF-BB of the concentration of 25 microg/L. there was no difference in the level of TGF-beta1 in the cell culture supernatant among different groups., Conclusion: Phosphorylation of ERK and TGF-beta1 have an important role in asthma airway remodeling; PDGF-BB does not induce normal rat airway epithelial cells to product or release TGF-beta1 by phosphorylation of ERK. Glucocorticoids can inhibit phosphorylation of ERK.

Objective: Airway remodeling in asthma makes treatment of asthma very difficult, and study of its pathogenesis becomes very important. The present study aimed to explore the role of external signal regulated kinase (ERK) signal transduction pathway in airway remodeling in rats asthma model and regulatory effects of glucocorticoids on ERK signal transduction pathway and airway remodeling., Methods: Totally 80 male Sprague-Dawlay rats (6-8 weeks old, weighing about 120 g) were randomly divided into control groups (30 rats), asthma groups (30 rats) and treated groups [including a group intervened with dexamethasone (DM group) and budesonide (BUD group), each had 10 rats]. The rats were sensitized for inducing asthma by intraperitoneal injection of ovalbumin and Al (OH)(3) and were repeatedly exposed to aerosolized ovalbumin for 4, 8, or 12 weeks [respectively called 4, 8 or 12 wk asthma group (A4, A8 or A12 group), each had 10 rats]; and correspondingly control rats were intraperitoneally injected with 0.9% NaCl, then were repeatedly exposed to 0.9% NaCl for 4, 8, or 12 weeks [respectively called 4, 8 or 12 wk control group (C4, C8 or C12 group), each had 10 rats]; DM group rats were repeatedly exposed to aerosolized ovalbumin for 8 wk, and BUD group rats for 12 wk. Total bronchial wall thickness (Wat) and smooth muscle thickness (Wam) were measured by an image analysis system. Concentrations of PDGF-AB in serum were measured by sandwich ELISA. Phospho-ERK (P-ERK) and c-Fos were detected by immunohistochemical technique; lung tissue extracts were analyzed for phosphorylation of ERK by Western blotting., Results: Wat and Wam in all asthma groups were significantly higher than those in corresponding control groups (P < 0.01, respectively), those of the treated groups were significantly lower than asthma groups (P < 0.01). The concentrations of PDGF-AB in serum of asthma groups [(228 +/- 18) pg/ml, (293 +/- 77) pg/ml, (225 +/- 66) pg/ml for A4, A8, A12 groups, respectively] were all significantly higher than those of the control groups [(160 +/- 14) pg/ml, (165 +/- 29) pg/ml and (164 +/- 27) pg/ml for C4, C8, C12 group, respectively] (P < 0.01 or P < 0.05); the value of DM group [(157 +/- 46) pg/ml] was significantly lower than that of the group A8 (P < 0.01), no significant difference was found when the values of BUD group [(208 +/- 40) pg/ml] was compared with that of A12 group (P > 0.05). Mean absorbance values (by immunohistochemistry) of P-ERK and c-Fos in asthma groups were significantly higher than those in corresponding control groups (P < 0.01, respectively), DM group had a significantly lower value than group A8 (P < 0.01), BUD group had a significantly lower value than group A12 (P < 0.01); absorbance (by Western blot) of P-ERK in A4, A8, A12 group was significantly higher than that in C4 and C8 group, the value of DM group was significantly lower than that of group A8 (P < 0.01), and that of BUD group (1.8 +/- 0.2) was significantly lower than that of group A12 (P < 0.01)., Conclusion: Asthmatic rats have higher concentrations of PDGF-AB in serum and phosphorylation of ERK and c-Fos; glucocorticoids inhibit phosphorylation of ERK and c-Fos in asthmatic rats, and to some extent also inhibit Wat and Wam.