Effects Of Heme Oxygenase-1/Carbon Monoxide On The Mitochondrial Fusion In Rat Alveolar Epithelial Type ? Cells Stimulated By LPS

There are millions of patients with sepsis in the world every year and more than25%of the patient will be in treatment failure^[1].The pathogenesis of sepsis is quite complex.Excessive activation of inflammatory system and the release of cytokines are important parts of the pathogenesis of sepsis.During sepsis,lung is the most fragile organ.Sepsis-induced acute lung injury?ALI?occurs the earliest and the incidence of sepsis-induced ALI is the highest.At present,sepsis-induced ALI is treated with antibiotics,mechanical ventilation and others,but there are no effective treatments to cure ALI.To explore the explicit pathogenesis of sepsis-induced ALI is of great significance.Compared with healthy lungs,one of the obvious pathological changes of sepsis-induced ALI is dysfunction of alveolar epithelial barrier.Alveolar epithelial type?cells are important components of the alveolar epithelial barrier.Mitochondria fusion is one of the most important cellular activities.Therefore,we think that mitochondrial fusion in alveolar epithelium type ??AEC ??cells plays an important role in sepsis-induced ALI.HO-1 and carbon monoxide have endogenous protective effects during sepsis^[2],but the effects of HO-1 and carbon monoxide on mitochondrial fusion in alveolar epithelial type ? cells stimulated by LPS is not clear.Objective To investigate the effects of heme oxygenase-1 and carbon monoxide?HO-1/CO?on mitochondrial fusion in rat alveolar epithelial type ? cells stimulated by LPS.Methods The cultured rat alveolar epithelial type ? cells were seeded in 96-well plate at a density of 2×10⁵/ml and were randomly divided into 7 groups?n=5each?using a random number table:group LPS?group L?,group LPS+CORM-2?group LC?,group LPS+Hemin?group LH?,group LPS+ZnPP-IX?group LZ?,group LPS+CORM-2+ZnPP-IX?group LCZ?,group LPS+Hemin+ZnPP-IX?group LHZ?and group control?group C?.Group L was stimulated with 10?g/ml LPS.Group LC and group LH were pretreated with CORM-2 100?M and Hemin 20?M respectively for 1h followed by stimulation with LPS.Group LZ was pretreated with ZnPP 10?M for 0.5h before stimulation with LPS.Group LCZ and group LHZ were pretreated with CORM-2 100?M and Hemin 20?M respectively for 1h,and the other treatments were similar to those previously described in group LZ.24 hours later,tumor necrosis factor-??TNF-??and interleukin-6?IL-6?in the supernatant were determined by ELISA,the expression of HO-1,Mfn1,Mfn2 and OPA1 were measured by Western blot.Results Compared with group C,IL-6,TNF-?concentration were increased,HO-1 protein expression was up-regulated,Mfn1,Mfn2 and OPA1 were down-regulated in the other groups.Compared with group L,IL-6,TNF-?concentration were decreased,HO-1,Mfn1,Mfn2 and OPA1 were up-regulated in group LC and group LH;IL-6,TNF-?concentration were increased,HO-1,Mfn1,Mfn2 and OPA1 were down-regulated in group LZ.There were no obvious difference in the parameters mentioned above between group LH and group LC,and among group LPS,group LHZ and group LCZ.Conclusion HO-1/CO promotes mitochondrial fusion and alleviates inflammatory response in rat alveolar epithelial type ? cells stimulated by LPS.