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OBJECTIVE To investigate the impacts of isorhynchophylline （IRN） on airway inflammation in asthmatic mice by regulating the monocyte chemotactic protein-1 （MCP-1）/CC chemokine receptor 2 （CCR2） signaling pathway. METHODS The asthmatic mice model was established by injecting and inhaling ovalbumin. The successfully modeled mice were randomly grouped into asthma group， IRN low-dose group （IRN-L， intragastric administration of 10 mg/kg IRN）， IRN high-dose group （IRN-H， intragastric administration of 20 mg/kg IRN）， IRN-H+CCL2 group [intragastric administration of 20 mg/kg IRN+intraperitoneal injection of 7.5 ng CC chemokine ligand 2 （CCL2）] and positive control group （intraperitoneal injection of 2 mg/kg dexamethasone）. The mice injected and inhaled with sterile phosphate-buffered solution were included in the blank control group， with 10 mice in each group. The mice in administration groups were given relevant medicine once a day， for consecutive 2 weeks. The levels of airway hyperreactivity indexes such as enhanced （Penh） value， tumor necrosis factor-α （TNF-α），interleukin-13 （IL-13） and IL-4 in serum， the number of eosinophil （EOS）， lymphocyte （LYM） and neutrophils （NEU） in alveolar lavage fluid and the protein expressions of MCP-1 and CCR2 in lung tissue were observed in each group； the pulmonary histopathological changes were observed， and inflammatory cell infiltration score was evaluated. RESULTS Compared with the blank control group， the infiltration of inflammatory cells in the lung tissue of mice was more significant in the asthma group， and there was swelling and shedding of cells； inflammatory infiltration score， Penh value， the levels of IL-4， IL-13 and TNF-α， the number of EOS， NEU and LYM， the protein expressions of MCP-1 and CCR2 were increased significantly （P＜0.05）. Compared with the asthma group， the pathological injuries of the IRN-L group， IRN-H group and positive control group were improved， and the above quantitative indexes were decreased significantly （P＜0.05）. Compared with the IRN-L group， the above quantitative indexes of the IRN-H group and positive control group were decreased significantly （P＜0.05）. There was no statistical significance in the above quantitative indexes between the IRN-H group and the positive control group （P＞0.05）. Compared with the IRN-H group， the above quantitative indexes of the IRN-H+CCL2 group were increased significantly （P＜0.05）. CCL2 reversed the protective effect of high-dose IRN on asthmatic mice. CONCLUSIONS IRN may reduce the release of airway inflammatory factors in asthmatic mice by inhibiting the activation of the MCP-1/CCR2 signaling pathway， so as to achieve the purpose of improving asthma.
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Objective@#To investigate the role and mechanism of Ly6Chigh monocyte in mice with ventilator-induced lung injury (VILI).@*Methods@#Forty-eight healthy male SPF C57BL/6 mice were divided into spontaneous breathing group (n = 8), normal tidal volume (VT) group (VT was 8 mL/kg, n = 8), and high VT group (VT was 20 mL/kg, n = 32). The mice in the high VT group were subdivided into 1, 2, 3 and 4 hours subgroups, with 8 mice in each subgroup. All mice underwent direct tracheal intubation, those in the spontaneous breathing group maintained spontaneous breathing, and those in the normal VT group and high VT group were mechanically ventilated with different VT. After ventilation for 4 hours, bronchoalveolar lavage fluid (BALF) was collected to determine total protein, and the levels of inflammatory factors including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were determined by enzyme-linked immune sorbent assay (ELISA). The lung tissues were harvested to determine the wet/dry (W/D) ratio, and lung tissue injury was assessed in terms of lung histopathologic examination after hematoxylin-eosin (HE) staining under the light microscope. The protein expressions of monocyte chemotactic protein-1 (MCP-1) and CC-chemokine receptor 2 (CCR2) in lung tissues were determined by Western Blot. Flow cytometry was used to detect the proportion of Ly6Chigh monocyte in lung tissue.@*Results@#The histopathology of lung tissue structures was normal in the spontaneous breathing group and the normal VT group. Inflammatory reaction began to appear at 2 hours of high VT ventilation, and inflammatory reaction was gradually aggravated with the time extension. Compared with the spontaneous breathing group, the total protein, TNF-α, and IL-1β levels in BALF, the lung W/D ratio and MCP-1 expression were increased from 2 hours of high VT ventilation [total protein in BALF (g/L): 1.05±0.13 vs. 0.58±0.11, TNF-α in BALF (ng/L): 116.86±16.14 vs. 38.27±8.00, IL-1β in BALF (ng/L): 178.98±10.41 vs. 117.56±23.40, lung W/D ratio: 5.76±0.27 vs. 4.98±0.39, MCP-1/GAPDH: 0.87±0.19 vs. 0.29±0.12, all P < 0.05], and CCR2 expression and the proportion of Ly6Chigh monocyte was significantly increased from 3 hours of high VT ventilation [CCR2/GAPDH: 0.84±0.19 vs. 0.24±0.11, Ly6Chigh monocyte proportion: (9.01±2.47)% vs. (1.06±0.35)%, both P < 0.05], and they all showed an increased tendency with the time extension. There was no significant difference in the parameters mentioned above among the spontaneous breathing group, normal VT group and high VT ventilation 1-hour group.@*Conclusion@#Ly6Chigh monocytes are involved in VILI, which aggravate VILI by activating the MCP-1/CCR2 axis.
ABSTRACT
Objective To investigate the role and mechanism of Ly6Chigh monocyte in mice with ventilator-induced lung injury (VILI). Methods Forty-eight healthy male SPF C57BL/6 mice were divided into spontaneous breathing group (n = 8), normal tidal volume (VT) group (VT was 8 mL/kg, n = 8), and high VT group (VT was 20 mL/kg, n = 32). The mice in the high VT group were subdivided into 1, 2, 3 and 4 hours subgroups, with 8 mice in each subgroup. All mice underwent direct tracheal intubation, those in the spontaneous breathing group maintained spontaneous breathing, and those in the normal VT group and high VT group were mechanically ventilated with different VT. After ventilation for 4 hours, bronchoalveolar lavage fluid (BALF) was collected to determine total protein, and the levels of inflammatory factors including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were determined by enzyme-linked immune sorbent assay (ELISA). The lung tissues were harvested to determine the wet/dry (W/D) ratio, and lung tissue injury was assessed in terms of lung histopathologic examination after hematoxylin-eosin (HE) staining under the light microscope. The protein expressions of monocyte chemotactic protein-1 (MCP-1) and CC-chemokine receptor 2 (CCR2) in lung tissues were determined by Western Blot. Flow cytometry was used to detect the proportion of Ly6Chigh monocyte in lung tissue. Results The histopathology of lung tissue structures was normal in the spontaneous breathing group and the normal VT group. Inflammatory reaction began to appear at 2 hours of high VT ventilation, and inflammatory reaction was gradually aggravated with the time extension. Compared with the spontaneous breathing group, the total protein, TNF-α, and IL-1β levels in BALF, the lung W/D ratio and MCP-1 expression were increased from 2 hours of high VT ventilation [total protein in BALF (g/L): 1.05±0.13 vs. 0.58±0.11, TNF-α in BALF (ng/L): 116.86±16.14 vs. 38.27±8.00, IL-1β in BALF (ng/L): 178.98±10.41 vs. 117.56±23.40, lung W/D ratio: 5.76±0.27 vs. 4.98±0.39, MCP-1/GAPDH: 0.87±0.19 vs. 0.29±0.12, all P < 0.05], and CCR2 expression and the proportion of Ly6Chigh monocyte was significantly increased from 3 hours of high VT ventilation [CCR2/GAPDH:0.84±0.19 vs. 0.24±0.11, Ly6Chigh monocyte proportion: (9.01±2.47)% vs. (1.06±0.35)%, both P < 0.05], and they all showed an increased tendency with the time extension. There was no significant difference in the parameters mentioned above among the spontaneous breathing group, normal VT group and high VT ventilation 1-hour group. Conclusion Ly6Chigh monocytes are involved in VILI, which aggravate VILI by activating the MCP-1/CCR2 axis.
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Objective To explore effects of apoAI on MCP?1 levels in the plasma and the Ly6Chi monocyte proportion in the blood and spleen of atherosclerotic mice,as well as on CCR2 expression in vitro. Methods Sixteen male apoE?/?mice were fed with high cholesterol diet for 12 weeks. Mice were randomly divided into control and apoAI groups and were administered with PBS or apoAI(40 mg/kg),respectively,via tail vein on the 1st and 3rd day before sacrifice. Mice in both groups were administered LPS(25μg/mouse)via intraperitoneal injection 12 h before sacrifice. Plas?ma levels of MCP?1 were determined using ELISA,and the Ly6Chi monocyte proportion was analyzed using flow cytometry. In addition,human monocytic THP?1 cells were randomly divided into control and apoAI(10 mg/L)?treated groups,pretreated with corresponding intervention,and incubated with LPS(10μg/L). CCR2 expression levels were measured by Western blotting. Results Compared with the control treatment, apoAI treatment remarkably reduced MCP?1 levels in plasma and Ly6Chi monocyte proportion in the blood and spleen(P<0.01). Furthermore, apoAI treatment inhibited CCR2 expression in monocytes in vitro(P<0.05). Conclusion apoAI can reduce MCP?1 levels in plasma and the Ly6Chi monocyte proportion in the blood and spleen and can inhibit CCR2 expression in monocytes in vitro.
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PURPOSE: This study was undertaken to elucidate whether CC chemokine receptor 2 (CCR2) exists in human peritoneal mesothelial cells (HPMCs) and whether monocyte chemoattractant protein-1 (MCP-1) has direct effects on epithelial to mesenchymal transition (EMT) and fibronectin expression in HPMCs. METHODS: HPMCs were isolated from a piece of human omentum and were incubated with M199 media containing 5.6 mM glucose (LG), 5.6 mM glucose+94.4 mM mannitol (LG+M), LG+10 ng/mL recombinant human MCP-1 (LG+MCP-1), or 100 mM glucose (HG) with or without a specific inhibitor of CCR2, 1.0 micrometer RS102895, for 4 days. Levels of secreted MCP-1 in culture media were determined by ELISA. Western blot was performed to determine fibronectin, E-cadherin, alpha-smooth muscle actin (alpha-SMA) and CCR2 protein expression. RESULTS: MCP-1 protein levels were significantly increased in HG-conditioned media compared to LG media (p<0.05). CCR2 protein was expressed in HPMCs, but there was no difference between LGand HG-stimulated cells. alpha-SMA protein expressions in HG and LG+MCP-1 groups were significantly higher relative to LG cells, while E-cadherin protein expressions were decreased in HG and LG+ MCP-1 groups compared to LG cells (p<0.05). In addition, there were significant increases in fibronectin mRNA and protein expression in HG and LG+MCP-1 groups (p<0.05). These HG-induced changes were significantly abrogated upon pre-treatment with RS102895. CONCLUSION: HG and MCP-1 directly induce EMT and enhance fibronectin expression in HPMCs, and these HG-induced changes were attenuated by the inhibition of MCP-1/CCR2 system, suggesting that increased MCP-1 levels by HG may contribute to the development of peritoneal fibrosis.