Study On The Inhibitor Of Complement C3a Against The Invasion Of Toxoplasma Gondii In Brain

Toxoplasma gondii(T.gondii)is an opportunistic intracellular parasitic protozoan.Due to its wide range of infections on warm-blooded animals,it cause global zoonotic diseases.Multiple organs in the animal become hosts for T.gondii.After oral infection,T.gondii will pass through the digestive tract and enter the blood circulation system,and then be transported to multiple host tissues or cells,easily causing inflammation of multiple organs.T.gondii is particularly harmful to the brain.Studies have shown that more than90% of patients who die from toxoplasmosis also have high-risk secondary paralysis due to toxoplasmosis encephalitis.T.gondii exists for a long time after entering the brain,and it’s easy to induce encephalitis when the animal’s immunity is low.It’s also closely related to a variety of neurological symptoms,affecting animal behavior.According to the genotyping of T.gondii,it can be classified into typeⅠ,typeⅡ and typeⅢ.Among them,typeⅡstrains are the most widespread in the world.Me49 strains can be isolated in various animals and are typical representatives of typeⅡ attenuated strains.It is neurotrophic and penetrate the blood-brain barrier(BBB)to invade the Central Nervous System(CNS),transform into bradyzoites and exist for a long time,causing damage to the host’s memory,learning and recognition capabilities.Widespread popularity in farms will reduce the productivity of economic animals and cause serious economic losses.Complement C3 is an important biomolecule that activates the complement system in the innate immune system.Complement C3 will rapidly split into C3 a and C3 b in the activated state,and its lysate C3 a protein plays an important role in the occurrence of inflammation and anti-inflammatory.The research group has previously demonstrated that T.gondii invasion of the CNS induces high expression of complement C3.Studying the cellular role of complement C3 a during the invasion of T.gondii in brain help to understand the mechanism of T.gondii invasion and the precise selection of drugs to prevent and treat toxoplasmosis encephalitis.In this study,a variety of methods including transmission electron microscopy technology,real-time quantitative PCR technology,Western Blot technology,Pull down technology and other methods are used to comprehensively analyze the effect of complement C3 a on microvascular endothelial cells.Screening drugs for the effect of C3 a on the BBB during the invasion of T.gondii into the brain to resist the attack of T.gondii on the BBB.Through research,we found that complement C3 a promote the invasion of T.gondii into the CNS,which may be achieved by affecting tight junction proteins or cytoskeletal proteins;the prokaryotic expression protein of C3 a is constructed,and C3 a and microvascular endothelial cell membranes are formed by Pull down joint LC/MS to Screen of protein interaction proteins.Finally,according to the characteristics of the effect of C3 a to cells,CVF,C3 a R antagonists,NSC23766 and Anax1 were tested to resist the invasion of T.gondii.It was found that C3 a R antagonists had the best inhibitory ability of T.gondii into the brain,followed by CVF,Anax1 and NSC23766,and the difference in inhibitory ability between the three was not obvious.Screening for complement C3 a inhibitors that inhibit the entry of T.gondii into the brain is of great significance for the development of drugs to prevent and treat Toxoplasma encephalopathy.