Effect Of Ovalbumin Stimulation On The Innate Immunity Of Caenorhabditis Elegans And The Preliminary Study Of Its Mechanism

Ovalbumin(OVA),the main protein in egg white,has many biological activities but also has strong allergenicity.OVA can be recognized by the body’s immune system and triggers IgE-mediated type I hypersensitivity reaction.Innate immunity is the first line of defense against foreign matters,and it plays a critical role in the body’s resistance to pathogen infection,but the mechanism of innate immunity in OVA allergy is still unknown.Caenorhabditis elegans(C.elegans)is a simple model organism with the only innate immune system,and many of its immunological pathways are conserved with those of humans.It is helpful to understand the specificity of innate immunity by OVA stimulation using C.elegans.Therefore,in this thesis,C.elegans was employed to construct the innate immunity model stimulated by OVA.The effect of OVA stimulation on C.elegans was assessed utilizing the apparent physiological and biochemical indicators of C.elegans.The effect of OVA stimulation on the innate immune system of C.elegans was then demonstrated using genome sequencing methods to characterize innate immune genes at the molecular level.The main methods,results and conclusions of this work were as follows.1.The apparent physiological indicators of L1 stage C.elegans stimulated by different concentrations of OVA for 24 h,48 h,72 h and 96 h were measured,respectively,followed by measuring the biochemical indicators of L1 stage C.elegans stimulated by different concentrations of OVA for 24 h,48 h and 72 h.The results showed that the body lengths of C.elegans stimulated by 1 mg/mL OVA were 100%、116.2%、112.5% and 112.5% of the control group,respectively,indicating that 1mg/mL OVA promoted the growth of C.elegans.The body lengths of C.elegans stimulated by 10 mg/mL OVA were 72.6%、89.9%、97.1% and 112.7% of the control group,respectively,indicating that 10 mg/mL OVA inhibited and then promoted the growth of C.elegans.The lipofuscin accumulation was decreased,the glutathione production was increased,and the activity of catalase was increased by 45.3% after being stimulated by 1 mg/mL OVA,demonstrating the antioxidant impact.The lipofuscin accumulation was increased while the glutathione production was decreased after being stimulated by 10 mg/mL OVA,demonstrating the stress effect.When the concent of ROS was decreased after 72 h of stimulation with 10 mg/mL OVA,the stress impact was minimized.2.The apparent physiological and biochemical indicators of L4 stage C.elegans were assessed after stimulating by different concentrations of OVA for 24 h and 48 h.Results showed that the body length and locomotion behavior of C.elegans were not significantly changed.The peroxidase activity of C.elegans was increased by 28.2%following 48 h of stimulation with 0.1 mg/mL OVA.The lipofuscin accumulations were increased while the glutathione productions were decreased after being stimulated with1 mg/mL and 10 mg/mL OVA.The antioxidant impact of OVA on C.elegans was seen at low concentrations,while the stress effect was seen at high concentrations.3.The genomes of L1 stage C.elegans were sequenced after being stimulated with 1 mg/mL OVA for 72 h,10 mg/mL OVA for 24 h,and 10 mg/mL OVA for 72 h,and the mechanism of OVA stimulation on the innate immunity of C.elegans was preliminarily explored.The results showed that some innate immunity genes of C.elegans were down-regulated by 1 mg/mL OVA stimulated for 72 h,but the innate immunity of C.elegans was not significantly affected by the up-regulation of stress resistance genes to balance stress.After being stimulated with 10 mg/mL OVA for 24 h,the ERAD and lysosomal pathways of C.elegans were up-regulated,and the protein misfolding might be enhanced,and the activation of DAF-16 might be inhibited,which led to the down-regulation of some innate immunity genes.After being stimulated with10 mg/mL OVA for 72 h,the unfolded protein response of C.elegans was activated to alleviate the stress caused by OVA,and the genes related to the cytochrome P450 metabolism of xenobiotics,which may play a role in OVA metabolism,were upregulated,enhancing the resistance and metabolic ability of C.elegans to OVA.To sum up,the low concentration of OVA has an antioxidant effect on C.elegans,whereas the high concentration of OVA has a stress effect on C.elegans and downregulated the innate immunity genes of C.elegans.L1 stage C.elegans may develop resistance after being stimulated for 72 h with 10 mg/mL OVA.