Effects Of Cryptoporus Polysaccharide On Experimental Acute Lung Injury And Its Effect Mechanism

BackgroundAcute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS). the development of which are associated with pneumonia, aspiration, sepsis, acute pancreatitis, drug overdose and so on are clinical syndromes associated with acute respiratory failure. It often showed as refractory hypoxemia, acute respiratory distress in clinical features, bilateral pulmonary infiltrates on chest radiograph, and often associated with multiple organ failure in later stage. There is no specific medicine to control ALI or ARDS as yet, so searching for the new therapy target and exploring the new drug to treat ARDS become the work of scientific research.Cryptoporus volvatus ferment substance (CVFS) or cryptoporus polysaccharide (CP) had markedly protective effect on allergic inflammation in guinea pigs and rats in our previous studies. In this study, we investigate that whether CP has protective effects on lipopolysaccharide (LPS)-induced acute lung injury in mice and rats, and search for its possible mechanism.Objective:To investigate the protective effects of CP infusion via vein on anti-inflammatory, anti-oxygenization, relief of lung edema, amelioration of oxygen partial pressure inexperimental acute lung injury and its mechanism.Methods:Part 1: Protective effects of cryptoporus polysaccharide on acute lung injury in miceAcute lung injury was induced in ICR mice by instilling intratracheally with LPS (4 mg· kg^-1). CP and positive drug (dexamethasone, DXM) were given (iv) twice 10 min before and 3 hours after LPS challenge. The effects of CP on acute lung injury were observed 6 h later by assessing the changes of total inflammatory cells, neutrophils, protein content, myeloperoxidase (MPO) and superoxide anion activity in brochoalveolar lavage fluid (BALF), analyzing vascular permeability in vivo and wet weight /dry weight ratio, tumor necrosis factor -α (TNF-α ) and interleukin -10 (IL-10) levels in supernatant of lung tissue and observing the pathological changes of lung inflammatory infiltration, lung injury and edema in pathological sections.Part 2: Protective effects of cryptoporus polysaccharide on acute lung injury in ratsAcute lung injury was induced in Sprague-Dawley rats by instilling intratracheally with LPS (5 mg · kg^-1). CP and positive drug DXM were given (iv) slowly at a constant speed (0.5 ml·h^-1)10 min before LPS challenge. The effects of CP on acute lung injury were observed 6 h later by assessing the changes of arterial partial pressure of oxygen (P_aO₂), arterial partial pressure of carbon dioxide (P_aCO₂), PH value in blood and gas analysis, total inflammatory cells, neutrophils, MPO activity in BALF and observing the pathological changes of lung inflammatory infiltration, lung injury and edema in pathological sections.Results:Part 1: Protective effects of cryptoporus polysaccharide on acute lung injury in mice1. CP (1, 3, 10, 30 and 100 mg·kg^-1, iv) reduced total inflammatory cells markedly in BALF in a dose-dependent manner, and the inhibitory rates were 10.9, 21.5, 41.3, 48.3 and 54.3% respectively; it also reduced neutrophils in a dose-dependent manner, and the inhibitory rates were 30.7, 47.7, 65.5, 75.3 and 82.2% respectively . The inhibitory rates of DXM (0.5 mg·kg^-1, iv) of the two indexes were 60.0% and 66.7% respectively, the intensity was about 20 times of CP.2. CP (3, 10, 30 and 100 mg·kg^-1, iv) reduced total protein content markedly in BALF, and the inhibitory rates were 0, 9.7, 24.7 and 24.0 % respectively; the inhibitory rate of DXM (0.5 mg·kg^-1) was 33.8%.3. CP (1, 3, 10, 30 and 100 mg·kg^-1, iv) reduced the leakage of Evans Blue markedly in BALF in a dose-dependent manner, and the inhibitory rates were 17.2, 41.4, 44.7, 65.2 and 67.1 % respectively; and the inhibitory rate of DXM (0.5 mg·kg^-1) was 57.0 %, the intensity was about 20 times of CP.4. CP (1, 3, 10, 30 and 100 mg·kg^-1, iv) reduced myeloperoxidase (MPO) markedly in BALF in a dose-dependent manner, and the inhibitory rates were 6.6, 6.6, 9.2, 27.8 and 36.9%; the inhibitory rate of DXM (0.5 mg·kg^-1) was 25.1 %, the effect intensity of CP at the dose of 30 mg·kg^-1 was equal to that of DXM (0.5 mg·kg^-1). However, CP had no obvious effect on the level of superoxide anion activity(C₂^·-), which wasdifferent from DXM (0.5 mg·kg^-1).5. CP (1, 10 and 30 mg·kg^-1, iv) reduced tumor necrosis factor-α (TNF-α) markedly in supernatant of lung tissue in a dose-dependent manner, and the inhibitory rates were 39.2,43.8 and 50.9%; the dose of 10 mg·kg^-1 and 30 mg·kg^-1 groups had significantly less TNF-α amounts than that of model group (P<0.01), DXM (0.5 mg·kg^-1, iv) had inhibitory effect as well, and its inhibitory rate was 66.3%, the effect intensity of which was nearly equal to CP at the dose of 30 mg·kg^-1. Neither CP (1,10 and 30 mg·kg^-1, iv) nor DXM (0.5 mg·kg^-1, iv) could increase the level ofInterleukin -10 (IL-10) (P>0.05).6. CP (1,10 and 30 mg·kg^-1, iv) reduced lung wet weight/ dry weight ratio markedly in a dose-dependent manner, and the inhibitory rates were 7.0, 8.3 and 11.0%; the dose of 30 mg·kg^-1 groups reduced significantly lung wet weight dry weight ratio than that of model group (P<0.01), DXM (0.5 mg·kg^-1, iv) had inhibitory effect as well, and its inhibitory rate was 13.0%, the effect intensity of which was about 20 times of CP.7. CP (1, 3,10, 30 and 100 mg·kg^-1, iv) could improve the infiltration of PMNs in the interstitial of LPS-induced lung tissue and lung edema in a dose-dependent manner.Part 2: Protective effects of cryptoporus polysaccharide on acute lung injury in rats1. CP (1, 10, and 30 mg·kg^-1, iv)improved P_aO₂ in a dose-dependent manner, especially in CP at the dose of 10 mg·kg^-1 and 30 mg·kg^-1(P<0.05). while DXM had no effect on amelioration of P_aO₂. However, DXM had significant effect on amelioration of LPS-induced ascensus of P_aCO₂ (P<0.05).2. CP (1, 10, and 30 mg·kg^-1, iv) reduced total inflammatory cells markedly in BALF in a dose-dependent manner, the inhibitory rates were 0.75, 33.8 and 52.3% respectively; it also reduced neutrophils in a dose-dependent manner, and the inhibitory rates were 23.4, 80.3 and 87.4% respectively . The inhibitory rates of DXM (0.5 mg·kg^-1, iv) of the two indexes were 35.3% and 79.2% respectively, the effect intensity of which was equal to CP at the dose of 10 mg· kg^-1.3. CP (1, 10, and 30 mg·kg^-1, iv) reduced myeloperoxidase (MPO) markedly in BALF in a dose-dependent manner, and the inhibitory rates were 15.8, 30.6 and 34.0%, and the inhibitory rate of DXM (0.5 mg·kg^-1) was 34.4%.4. CP (1, 10, and 30 mg·kg^-1, iv) had no effect on reducing lung wet weight/ dry weight ratio in rat.5. CP (1, 10, and 30 mg·kg^-1, iv) could improve the infiltration of PMNs in the interstitial of LPS-induced lung tissue and lung edema in a dose-dependent manner.Conclusion:CP protected lung against not only decreasing TNF-α level in lung tissue, restraining infiltration of neutrophile granulocytes in lung tissue and capillary permeability, reducing the leakage of total protein content and water content in lung, but also decreasing the level of MPO in supernatant of BALF and improving histopathologic deterioration in LPS-induced acute lung injuries in mice. It also markedly ameliorated P_aO₂ in LPS-induced acute lung injuries in rats besides the effects of anti-inflammatory and improvement of histopathologic deterioration. All these results hinted that CP had the effects of anti-inflammatory, anti-oxygenization, relief of lung edema, amelioration of oxygen partial pressure, which suggested that it had the value of exploitation in treating ALI.