The Study On Changes Of Mfn2 And Ultrastructure In The Lungs Of Rats Which Induced Pulmonary Fibrosis By Paraquat Via Xuebijing Intervention

BackgroundParaquat(PQ) is a kind of herbicide,which has higher toxicity to people and causes the highest fatality rate of human acute poisoning.After poisoning,the vast majority of patients among the survival exist with pulmonary fibrosis.The mechanism of poisoning is not entirely clear,PQ is generally considered as an electron acceptor,which plays a role in intracellular redox reactions,generates a large number of reactive oxygen species,causes cell lipid peroxidation and oxidative damage.There still is no positive effected rescuing pharmacy.Mitochondria is cellular energy metabolism place and the center of oxidation.Their morphological,structure, number,distribution and metabolism are in response to inside and outside cellular environmental vulnerable impacts.Thus a significant change happened and this change is reversible in a certain range.Therefore,mitochondrion is one of the most sensitive indicators of cell disease or injury,and also an important basis of inspection for molecular pathology.Mitochondrial fusion protein(mitofusin,Mfn) gene play an important role in mitochondrial metabolism,apoptosis and cell signaling.Its role includes holding back vascular smooth muscle cell cycle,inhibiting cell proliferation,migration and remodeling.Mfn2 located in the mitochondrial outer membrane,promotes the fusion of mitochondrial.There has an evidence showed that Mfn2 can participate in regulation of mitochondrial metabolism.Whether Mfn2 to participate in paraquat poisoning pulmonary fibrosis is still to be studied. ObjecctiveIn this study,through the establishment of PQ poisoning rat model,using western methods detected expression of Mfn2 gene in lung tissue.TEM is used to view ultrastructural changes in lung tissue.Content of hydroxyproline which forms collagen fibers and results of Masson staining of lung tissue will tell the effect of pulmonary fibrosis treatment via Xuebijing.Investigation of another possible trigger point in mechanism of paraquat-induced pulmonary fibrosis is still studied.MethodsMale Wistar rats were randomly divided into PQ intoxication group(PQ Group), PQ poisoning+XBJ rescued group(PX) and control group(C group),each setted1d,3d,7d,14d four observation time in each group.Rats in PQ group were fed with PQ(50mg/kg),C group were given distilled water orally(1ml).After 30min exposure to PQ,PX group was given intraperitoneal injection with XBJ 4ml/kg,2 times/d,interval 12h.At the same time,rats of PQ group and C group were given intraperitoneal injection with saline 4ml/kg,2 times/d.30min later of the rats were killed,lung tissue samples were taken for Western bloting,hydroxyproline quantitative,TEM detection,Masson staining and HE staining.Result(1)In HE staining of lung tissue,PQ group performances the most inflammatory at 3d.7d later,exudate in the alveolar cavity starts to organize,and fibroblasts hypertrophy is going,secreting of thin collagen fibers.The formation of a more delicate fibrous tissue can be seen as alveolar cavity fibrosis.At 14d fibroblast hyperplasia occurrs substantially,alveolar structure collapse,destruction,collagen deposition and the initial of pulmonary fibrosis forms.At each time,PX group changes a lesser extent than the PQ group in pathological.(2) In Masson staining,PQ group can be seen that the degree of pulmonary fibrosis significantly heavier than C group and PX group at 14d.The degree of alveolitis and pulmonary fibrosis in PQ groups is significantly higher than C group.(3) At 7d,14d the content of lung tissue HYP in PQ group is significantly higher compared with C group(P＜0.01).PX group compared with the PQ group,the content of HYP is significantly lower than PQ group at the same time(P＜0.05).(4)TEM observation:At 14d,PQ group has relatively few mitochondria,many of them happen degeneration,swelling and destruction;local basement membrane of lung tissue discounts,alveolar collapse,interstitial collagen fibers increased and local fibrosis gradually obvious.Various manifestations are serious than PX Group.(5)Mfn2 gene expression in PX Group is in the persistently high,while Mfn2 gene expression in PQ group gradually increased and expression level exceeds the PX group at 14d.Expression in C group is relatively low level.ConclusionXBJ can reduce lung inflammatory response caused by paraquat poisoning, reducing pulmonary fibrosis and the severity of illness.The mechanism is regulating expression of Mfn2 gene and increasing it.