The Effect Of PINK1/Parkin-Mediated Mitophagy On Aflatoxin B₁-induced Liver Injury In Mice

Aflatoxin B₁（AFB₁）is a highly toxic mycotoxin,causeing liver injury in human and animals.Oxidative stress is the main predisposing factor in AFB₁-induced liver injury,which can lead to liver mitochondrial damage.Impaired mitochondria further triggers NLRP3 inflammasome hyperactivation,worsening liver injury.While mitophagy specifically removes damaged mitochondria to defend against multiple factors-induced liver injury.The PINK1/Parkin pathway is a classic pathway to regulate mitophagy,but its role in AFB ₁-induced liver injury in mice is unclear."PINK1/Parkin-mediated mitophagy protects AFB₁ against liver injury in mice"was used as the theoretical hypothesis in the study.The following two studies are proposed:（1）AFB₁ subchronic toxicity test:C57BL/6 wild-type（WT）male mice were randomized to the control group（CG）,low dose group（LG）,medium dose group（MG）,and high dose group（HG）.Mice were orally exposed to AFB₁ for 28 d in succession.Determine the mouse liver structure and function,oxidative stress status,mitochondrial structure and function,NLRP3 inflammasome,and mitophagy level,aiming to clarify the correlation between mitophagy and liver injury in AFB₁-exposed mice,and screen the optimal exposure dose of AFB₁ for subsequent intervention trials;（2）Parkin knockout(Parkin^-/-)intervention test:WT and Parkin^-/-C57BL/6 male mice were divided into WT control group（WCG）,Parkin^-/-control group（PCG）,WT AFB₁ exposure group（WAG）,Parkin^-/-AFB₁ exposure group（PAG）.Mice were orally exposed to AFB₁ for 28 d in succession.Detect the mouse liver structure and function,oxidative antioxidant status,mitochondrial structure and function,NLRP3inflammasome,and mitophagy levels,aiming to explore the role of PINK1/Parkin-mediated mitophagy in liver injury caused by AFB₁ in mice.The results obtained from the tests are presented below:（1）Results of the AFB₁ subchronic toxicity test:1)Compared with CG,MG and HG mice were mentally depressed,slow to react,and had a significant reduction of weight gain,indicating that AFB₁ inhibited the growth of mice.2)Compared with CG,MG and HG mice showed the significant reduction of liver weight and liver coefficient,micrographic and ultrastructural damage of livers,and increased AST and ALT activities,indicating AFB₁ resulted in the liver damage both in the structure and function in mice.3)Compared with CG,MG and HG mouse livers had a significant increase of ROS content and reduction of SOD activity,indicating that AFB₁ exposure increased oxidative stress in mouse livers.4)Compared with CG,MG and HG mice showed the liver mitochondrial ultrastructural damage,and the reduction ofΔΨM and ATP content,indicating AFB₁ induced mitochondrial damage both in the structure and function in mouse livers.5)Compared with CG,MG and HG mice showed the increased protein expression of hepatic NLRP3,Pro-Caspase-1,Caspase-1,ASC,IL-18,and IL-1β,indicating that AFB₁ activated NLRP3inflammasome in mouse livers.6)Compared with CG,MG and HG mice showed the increased protein expression of hepatic PINK1,p-Parkin,and LC3 II,and the reduction of p62 protein expression,indicating that AFB₁induced PINK1/Parkin mediated mitophagy.7)The MG and HG mice exhibited significant liver injury,while the MG showed the highest mitophagy levels.Thus,0.75 mg/kg was chosen as the AFB₁ exposure dose in the subsequent test.（2）Results of the Parkin^-/-intervention test:1)Compared with WAG,PAG mice showed serious mental depression,slow reaction,and reduction of weight gain,indicating that Parkin^-/-could exacerbate the growth impairment in mice.2)Compared with WAG,PAG mice showed decreased liver weights and liver coefficients,serious micrographic and ultrastructural damage of livers,and enhanced serum AST and ALT activities,indicating that Parkin^-/-could aggravate mouse liver injury both in structure and function.3)Compared with WAG,PAG mice showed the enhanced hepatic ROS and MDA content,and reduced SOD and GSH-Px activities,suggesting that Parkin^-/-could exacerbate the oxidative stress in mouse livers.4)Compared with WAG,PAG mice showed increased mitochondrial ultrastructural damage and decreasedΔΨM and ATP content,suggesting that Parkin^-/-could exacerbate mitochondrial injury both in the structure and function in mouse livers.5)Compared with WAG,PAG mice had enhanced protein expressions of hepatic NLRP3,Pro-Caspase-1,Caspase-1,ASC,IL-18 and IL-1β,indicating that Parkin^-/-could aggravate NLRP3inflammasome activation in mouse livers.6)Compared with WAG,PAG mice showed the decreased hepatic PINK1 and LC3 II protein expressions,and the enhanced protein expression of p62,suggesting that Parkin^-/-could inhibit mitophagy in mouse livers.Conclusions:PINK1/Parkin-mediated mitophagy is activated in AFB₁-induced liver injury,in which plays a protective role;The protective role is related to eliminating damaged mitochondria,restraining the oxidative stress and activation of NLRP3 inflammasome.