The Study On The Protective Effect And Mechanisms Of Curcumin In Rats With Sepsis-induced Acute Lung Injury

Sepsis is the systemic inflammatory response syndrome (SIRS) induced by infection. It is the common complication of severe trauma, burns, ischemia-reperfusion injury and surgery, and is the first cause of death in non-cardiac intensive care unit (ICU) patients. Lung is the most vulnerable target organ towards sepsis, acute lung injury (ALI) occurs early and the incidence is very high. During sepsis, the inflammatory cells produce large amounts of inflammatory mediators and lipid metabolism after stimulated by LPS, these inflammatory mediators and lipid metabolism which in turn recruit and activate other inflammatory cells in lung tissues, especially neutrophils and macrophages. Cytokines, chemokines, oxygen free radicals and protease, which are produced by activated inflammatory cells, expand the inflammatory response in a waterfall-like cascade, cause damage to alveolar epithelial cells and vascular endothelial cells and then permeability, affect the cell gap, water and sodium transport and surfactant production. A large number of liquid rich in protein and cellular components inpour to the lung tissue, causing the formation of permeability pulmonary edema, leading to hyaline membrane formation and alveolar collapse, accompanied by pulmonary fibrosis.Curcumin (Curcumin, Cur) is a plant poly-phenols extracted in turmeric, which shows a wide range of pharmacological effects, in addition to the line of traditional Chinese medicine for gas, scattered wind circulation, pass through the pain, but recent studies also reveal its effects of anti-inflammatory, antioxidant, scavenging oxygen free radicals, anti-fibrosis and anti-cancer and so on. The effects of curcumin may be related to inhibition of NF-κB and other transcription factors such as activator protein-1(AP-1), and has no obvious side effects. Studies have shown that curcumin in the treatment of inflammatory diseases have broad application prospects. But the biochemical basis and the signal path of anti-inflammatory by curcumin are not yet clear, curcumin used as a critical care treatment medicine must be further evaluated.Septic acute lung injury (ALI) model is established using rats cecal ligation and puncture (CLP). The levels of lung ventilation function indicators, lung permeability indicators, myeloperoxidase peroxidase (MPO), superoxide dismutase (SOD) and malondialdehyde (MDA) of lung tissue, lung pathological indicators, and cytokines such as TNF-α, IL-1β, IL-6and ICAM-1,MIP2, combined with the changes of NF-κB and MAPK signal transduction pathway (ERK, JNK and p38MAPK), are observed after curcumin treatment of septic lung injury, to clarify the mechanism of curcumin treatment of ALI induced by sepsis, providing a new idea for the prevention and clinical treatment to ALI. Objectives:To observe the effect of curcumin on septic acute lung injury in ratsMethods:Septic acute lung injury (ALI) model is established using rats cecal ligation and puncture (CLP). SD rats were randomly divided into5groups:sham group; model group; vehicle group; low dose (50mg/kg), high dose (200mg/kg) curcumin treatment group.8rats were killed during different time points after surgery (6h,12h,24h) to collect blood and lung tissue samples. The levels of arterial blood gas indicators, lung water content (lung wet/dry ratio), bronchoalveolar lavage fluid protein content and cell (total, neutrophils and lymphotes) counts, pathological changes of lung tissue under light microscopy, superoxide dismutase (SOD), malondialdehyde (MDA) and marrow peroxidase (MPO) activity of lung tissue and cytokines such as TNF-α, IL-1(3, IL-6, are observed in each time points and each group. The survival rate of72hours in each group is also observed.Results:1. Compared with the sham operation group, the indicators changed significantly in model group, which revealed that the model of septic ALI was successful and reliable. Compared with the sham operation group,(1) the pulmonary ventilation function decreased in model group:PaO2/FiO2and PaO2decreased significantly in model group (P<0.05or P<0.01);(2) the permeability of alveolar epithelial and microvascular increased in malignant in model group:lung water content, BALF protein content and cell (total, neutrophils and lymphotes) counts increased significantly in model group (P<0.05or P<0.01);(3) inflammation response occurred obviously in lung tissue in model group:the pathology score of lung tissue was significantly higher, BALF cytokines TNF-α, IL-1β, IL-6levels were significantly increased in model group (P<0.05or P<0.01);(4) neutrophil infiltration and the production of oxygen free radicals of lung tissue increased significantly, and antioxidant capacity decreased in model group:MPO activity and MDA level of lung tissue increased significantly, while SOD levels of lung tissue decreased significantly (P<0.05or P<0.01).2. Compared with model group, the indicators of lung injury improved in different degrees in different doses of curcumin treatment groups. Among the two different doses of curcumin, the protect effect on lung injury showed a dose-dependent effect. Compared with the model group,(1) curcumin treatment could improve the pulmonary ventilation function in rats:PaO2/FiO2and PaO2increased significantly with different doses of curcumin treatment (P<0.05or P<0.01), improved lung oxygenation status;(2) curcumin treatment could inhibit the permeability of alveolar epithelial and microvascular viciously increased:different doses of curcumin could reduce levels of lung water content, BALF protein content and cell (total, neutrophils and lymphotes) counts induced by septic ALI significantly (P<0.05or P<0.01);(3) curcumin treatment could inhibit inflammation:the pathology score of lung tissue was significantly lower after different doses of curcumin treatment, different doses of curcumin could inhibit the expression of BALF cytokines such as TNF-α, IL-1β, IL-6, induced by septic ALI significantly (P<0.01);(4) curcumin treatment could inhibit neutrophil infiltration and oxidative stress of lung tissue:MPO activity and MDA level of lung tissue decreased significantly, while SOD levels of lung tissue increased significantly in different doses of curcumin treatment group (P<0.05or P<0.01).3. The72h survival rate of sham operation group, model group, vehicle group and different doses of curcumin treatment group were observed. It was found that curcumin treatment could effectively improve the survival rate of septic ALI rats:the72h survival rate was80%in the50mg/kg dose of curcumin treatment group, it increased by40%compared with CLP group; the72h survival rate was90%in the200mg/kg dose of curcumin treatment group, it increased by50%compared with CLP group; and the72h survival rate was40%in the vehicle group, same as CLP group.Conclusions:Curcumin treatment played a protective role in septic ALI rats by reducing the lung microvascular endothelial cell injury and improving pulmonary ventilation function, inhibiting inflammation response and lung permeability induced by septic ALI. And curcumin treatment significantly increased the72h survival rate of rats. Objectives:To study the molecular mechanism of the effect of curcumin inhibiting the inflammation signaling pathway of IKK/NF-κB in septic acute lung injury ratsMethods:SD rats were randomly divided into3groups (n=10): sham group; model group; curcumin treatment group (200mg/kg). Rats were killed at12h after CLP to collect blood and lung tissue. Serum levels of TNF-a, MIP-2and ICAM-lwere measured by ELISA, TNF-α, MIP-2and ICAM-1mRNA of lung were measured by RT-PCR, the NF-κB DNA binding activity were measured by EMSA, the level of protein of NF-κB p65and p-IKKser180/pserl81and IκBα in the lung tissues were measured by Western blot.Results:1. Compared with the sham operation group, levels of serum TNF-a, ICAM-1and MIP-2and lung tissue TNF-a, ICAM-1and MIP-2mRNA expression increased significantly in model group (P<0.05or P<0.01); compared with sham control group, NF-κB DNA binding activity, nuclear protein levels of NF-κB p65, and p-IKKser180/βser181of lung tissue increased significantly, while IκBα of lung tissue decreased significantly in model group (P<0.05or P<0.01).2. Compared with model group, levels of serum TNF-a, ICAM-1and MIP-2and lung tissue TNF-a, ICAM-1and MIP-2mRNA expression decreased significantly in curcumin treatment group (P<0.05or P<0.01); Compared with model group, NF-κB DNA binding activity, nuclear protein levels of NF-κB p65, and p-IKKser180/βserl81of lung tissue decreased significantly, while IKBa of lung tissue increased significantly in curcumin treatment group (P<0.05or P<0.01).Conclusions:Effect of curcumin on septic ALI rats may be related to its inhibition of IKK/NF-κB signaling pathway to reduce the expression of inflammation-related gene and protein. Objectives:To study the molecular mechanism of the effect of curcumin inhibiting the inflammation signaling pathway of MAPK (ERK, JNK and p38MAPK) in septic acute lung injury rats.Methods:SD rats were randomly divided into3groups (n=6): sham group; model group; curcumin treatment group (10mg/kg). Rats were killed at12h after CLP to collect blood and lung tissue. The levels of pERK, pJNK and pp38MAPK protein of lung tissue were measured by Immunohistochemistry and Werstern blotting. TNF-a mRNA of lung were measured by RT-PCR. Serum levels of TNF-a were measured by ELISA.Results:1. Compared with the sham operation group, the levels of pERK, pJNK and pp38MAPK protein of lung tissue, TNF-a mRNA expression of lung tissue and serum TNF-a were significantly increased in model group (P<0.05or P<0.01).2. Compared with model group, the levels of pERK, pJNK and pp38MAPK protein of lung tissue, TNF-a mRNA expression of lung tissue and serum TNF-a were significantly decreased in curcumin treatment group (P<0.05or P<0.01). Conclusion:Effect of curcumin on septic ALI rats may be related to its inhibition of MAPK (ERK, JNK and p38MAPK) signaling pathway to reduce the expression of inflammation-related gene and protein.