Distribution Characteristics Of CXCL1/CXCR2 In Brain Tissue After Prion Infection And Its Relationship With Prion Deposition

Prion diseases（Prion diseases）are neurodegenerative diseases caused by prion virus infecting the central nervous system of human and many animals.The activation of glial cells is common in various infectious diseases and neurodegenerative diseases.After the activation of relevant glial cells,neuroinflammatory factors such as cytokines are produced,causing pathological damage to the central nervous system.It then plays an important role in the pathogenesis of diseases such as prion disease.Prion infection is accompanied by the activation of a large number of inflammatory cells in the central nervous system and the production of a large number of pro-inflammatory factors.When prions accumulate in the central nervous system,damage to relevant nerve cells is accompanied by activation of astrocytes and microglia.A large number of glial cell hyperplasia occurs in the central nervous system at the early stage of infection,accompanied by neuropathological damage,including but not limited to spongy lesions due to neuron loss.Previous studies on CXC chemokine ligand 1（C-X-C motif chemokine ligand 1,CXCL1）found that the content of CXCL1 increased in the brain tissue of animal models after prion infection.However,the relationship between Scrapie and Pr P^Sc（Scrapie like prion protein）has not been thoroughly studied,and the relationship between CXC Chemokine Receptor 2（CXCR2）,a receptor of CXCL1 and other chemokine ligands,and prion has not been clear.In order to explore the potential change trend of CXCL1 chemokine and CXCR2 receptor in central nervous system after prion infection and their relationship with prion deposition,specific antibodies of CXCL1/CXCR2 were selected in this study.Immunohistochemistry（IHC）,immunofluorescence（IF/ICC）,Western Blot and Quantitative Real-time PCR were used.The relationship between CXCL1/CXCR2 and prion deposition in brain tissue was analyzed according to the cell model of prion infection and different rodent models infected with pruritus factor.The expression levels of CXCL1 and CXCR2 were significantly reduced in prion-infected cell models.CXCL1/CXCR2 were widely distributed in the hippocampus,cortex,thalamus,cerebellum and medulla oblong of the brain of mice infected with two different pruritus infection factors（139A and ME7）,and the expression was most obvious in the thalamus.Comparison of tissue slices before and after infection showed that CXCL1/CXCR2 granuloid deposits appeared around brain tissue vacuolies,and common case features were observed with the progression of prion disease,such as large deposition of prion protein,glial cell proliferation and gradual loss of neurons.The dynamic results showed that CXCR2 expression level was the highest in the brain tissue of mice infected with pruritus factor for 120 days.In order to reveal the distribution characteristics of CXCL1/CXCR2 in the central nervous system and the relationship between CXCL1/CXCR2 and prion infection,we selected specific antibodies of CXCL1/CXCR2 and used IHC and IF methods to detect end-stage brain tissue slices of infected rodents.A comparative analysis showed that CXCL1 was co-located with markers of neurons and microglia,but not with markers of astroglia,in the hippocampus,thalamus,cerebellum and medulla oblongata of end-stage brain tissue slices of rodents infected with prion.CXCR2 was co-located with neuronal markers,but not with astrocyte and microglia markers.Finally,the brain tissues of rodents were selected for continuous sections.Specific immunohistochemical experiments were performed on CXCL1/CXCR2 and Pr P^Sc.The results showed that Pr P and CXCL1/CXCR2 were spatially co-located in different brain regions after infection.Positive signals of Pr P^Scand CXCL1/CXCR2 were observed at the same location,suggesting that CXCL1/CXCR2 was associated with Pr P^Scdeposition.In conclusion,CXCL1/CXCR2 showed different change characteristics in various prion infection models and infection stages,and CXCL1/CXCR2 changes were correlated with prion deposition in central nervous system.This study enriched the relevant data of chemokines involved in prion pathogenesis,and laid a scientific foundation for the study of prion pathogenesis.