| Background and objective: The systemic inflammation response syndrome (SIRS) is defined as the host response to infection and other forms of tissue injury. When SIRS is attributed to an identifiable infectious process, it is termed sepsis. A wide range of stress such as trauma and infection may cause injury of bowel barrier. Bacteria and endotoxin thus enter blood circulation through portal vein and lymph system resulting in enterogenous infection and toxic network. The majority of patients with SIRS or sepsis who fail to survive may present with septic shock and multiple organ dysfunction syndrome (MODS), representing the leading cause of death in clinical emergency. The most common manifestation of MODS is acute lung injury (ALI), which may progress to acute respiratory distress syndrome (ARDS) in the subset of patients at the severe end of the spectrum. ARDS is characterized by"severe hypoxemia, diffuse bilateral pulmonary inflitrates, and decreased lung compliance.Polymorphonuclear leukocytes (PMNs) have been recognized as important contributors to the pathogenesis of ARDS. In respond to SIRS, leukocytes become activated in pulmonary microcirculation and migrate to pulmonary interstitium and finally in the alveolar space. The infiltration of PMNs results in diffuse alveolar damage and capillary leak and edema formation. These progress are mediated by early-response cytokines, cell surface adhension molecules, and chemotactic molecules, chemokines. It is now accepted that inlammatory mediators plays a key role in the pathogenesis of ARDS. These mediators include tumor necrosis factor (TNF)-α, interleukins (e.g. IL-1,6), adehension molecules (e.g. intercellular adhension molecule-1/ICAM-1), mitogen-activated protein kinases (MAPKs), aquaporin (AQPs), et al.TNF include TNF-αand TNF-β. TNF-αis also called"cachectin", which represents as an improtant initial factor mediating septic shock, SIRS, ALI and MODS. It can induce formation of downstream proinflammatory cytokines that produce many cascade feedback..ICAM-1, also called CD54, involves in inflmmatory process via mediating adhesion of PMVEC-PMN which results in accumulation of PMN in the pulmonary microcirculation, formation of microthrombus and injury of vascular endothelium. These process lead to increase in vessel permeability and pulmonary edema and ALI develops.AQPs involve in transmembrane transport of free water. There are four types of AQPs in lung tissue, among which AQP-1 is located in the microvessel endothelium and plays an important role in maintaining water balance between vessel and interstitium.MAPK is one member of protein kinase family and is composed of three major groups: the extracellular regulated kinases (ERKs), the C-Jun N-terminal Kinases (JNKs) and the p38 MAPKs. The p38 MAPK kinase pathway shows close relationship with inflammatory reaction. Research reveal that p38 can promote expression of ICAM-1. It is activated in response to cytokines such as TNF-α, IL-1 and so on. Simultaneously, TNF-αand IL-1, 6, 8 are p38-dependent.Although more attention are paid to the pathophysiology of these mediators, the interaction among them and their gene modulation in the development of ALI due to sepsis still need to be elucidated. This research uses ALI animal model due to sepsis, which was established by intestinal perforation-induced peritonitis after cecum ligation. The pathogenesis and gene modulation mechanisms of lung edema were investigated via measuring the upmentioned gene expression in the inflammatory process. Furthermore, there is no research about the role of traditional Chinese medicine FU FANG QING XIA TANG (FFQX) in the pathophysiology of ALI. The mechenisms of FFQX as well as inhibitor of p38 were explored to reveal a new method for the preventation and treatment of sepsis and MODS. MethodsExperiment 1. SD rats were divided into four groups: SHAM group (n=10) : the rats didn't undergo any operation; ALI group (n=10): the cecum were ligated and produec intestinal perforation and induce ALI; FFQX group (n=10): FFQX (10mg/kg) were administrated by lavage immediately and 8 hours after formation of ALI respectively; antibiotics group (ALI+ Cefoperazone-Sulbactam, pfizer, n=10): Cefoperazone-Sulbactam (0.2g/Kg) were administrated by intravenous injection immediately and 8 hours after formation of ALI respectively. Specimen were collected 24 hours after ALI. Evaluate common condition of rats. Myeloperoxidase (MPO) were detected in homogenate from lung tissue. Serum TNF-α, IL-1 and IL-6 were measured from blood sample of inferior vena cava. Observe pathologic changes in lung tissue. Calculate the ratio of lung wet weight to dry weight (W/D).Experiment 2: Expression of TNF-α, IL-1 and IL-6, AQP-1, ICAM-1 and p38 in lung tissue were measured via immunohistochemistry and Western blotting, respectively. RT-PCR were performed to measure mRNA of these mediators.Experiment 3: p38I group (p38 inhibitor administration group, n=10): p38 inhibitor SB203580 (12.5 mg/Kg) were administrated by lavage 30minutes before the preparation of ALI animal model.Results1. In Experiment 1, the level of serum TNF-α, IL-1 and IL-6 and MPO in homogenate were significantly increased in ALI group compared with SHAM group (p<0.01). Pulmonary interstitial and intra-alveolar edema with exudate of RBCs and deposit of fibrin were seen. Endothelial cell of alveolar septum capillaries were obviously swollen. The ratio of W/D in ALI group is higher than that in SHAM group (p<0.01). Compared with ALI group, the level of serum TNF-α, IL-1 and IL-6 and MPO in homogenate were significantly decreased and the ratio of W/D is lower in FFQX group and antibiotics group (p<0.01 each). Narrowed alveolar septum, slight endothelial cell swelling and decreased bleeding and exudate can be seen in both FFQX group and antibiotics group.2. In Experiment 2, immunohistochemistry and Western blotting revealed the increased expression of TNF-α, IL-1 and IL-6, AQP-1, ICAM-1 and p38 in ALI group compared with SHAM group (p<0.01). The expression of TNF-α, IL-1 and IL-6, AQP-1, ICAM-1 and p38 in mRNA transcription level showed coincident results with protein level. The protein and mRNA expression of these upmentioned cytokines droped significantly in FFQX group and antibiotics group compared with ALI group (p<0.01 each) although there were no obvious difference between FFQX group and antibiotics group. The results suggest FFQX may inhibit expression of certain key cytokines to relieve lung injury due to sepsis.3. In Experiment 3, the protein and mRNA expression of these upmentioned cytokines droped significantly in FFQX group and p38I group compared with ALI group (p<0.01 each) and there were no significant difference between FFQX group and p38I group. The results suggest FFQX may inhibit certain procedure of p38 pathway to relieve lung injury due to sepsis.ConclusionsOur research revealed that overexpression of several major inflammatory factors such as TNF-α, IL-1 and IL-6 and activation of p38 MAPK kinase pathway in sepsis-induced ALI rat model may be the result of sepsis-induced ALI. However, AQP-1 had different effects from TNF-α, IL-1 and IL-6 in pathogenesis of ALI.FFQX can decrease the secretion of the several cytokines,also can alleviate the extent of sepsis-induced acute lung injury . And the relief of ALI after administration of FFQX and inhibitor of p38 suggested that specific inhibitors of p38 pathway may alleviate sepsis-induced lung injury. FFQX may inhibit p38 pathway which mediated overexpression of certain inflammatory factors. The use of FFQX can provide a new method for treating this disease.
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