Dynamic expression of inflammatory factors in experimental autoimmune uveitis in mice

Abstract

Background C57BL/6(B6) is a kind of routine mouse specie used in experimental autoimmune uveitis (EAU) research.Previous studies showed that the pathogenesis of uveitis related to inflammatory cytokines secreted by different helper T(Th) cells.However,the interaction of different Th cells in EAU is unclear.Objective This study was to investigate the dynamic changes of inflammatory factors in the spleen and serum after immunization in EAU mice.Methods Forty-four SPF B6 mice were immunized by injection of interphotoreceptor retinoid-binding protein (IRBP) and complete Freund adjuvant (CFA) emulsion via caudal vein and footpad.Indirect ophthalmoscope was used to examine the eyes 3 times per week and the inflammatory response was scored based on Thurau's criteria.In the thirty day after injection,20 model eyes were extracted and the sections of eye tissue were prepared for histopathological examination.The spleens of model mice were enucleated before injection and 2,5,10,15,20,25,30 days after injection,and reverse transcriptase PCR (RT-PCR) was used to detect the contents of interleukin-17 (IL-17) mRNA,interferon-γ (IFN-γ) mRNA,tumor necrosis factor-α (TNF-α) mRNA and IL-10 mRNA,and the contents of IL-17,IFN-γ,TNF-α and IL-10 in model serum were assayed by ELISA in 24 model mice.The experimental protocol and use of the animals were approved by Ethic Committee for Care and Use of Laboratory Animals of Shandong University of Traditional Chinese Medicine.Results Mild inflammatory response was seen in 12 days under the indirect ophthalmoscope with the scores of 0.5.The inflammatory scores peaked in 13-15 days with the scores of 1.0 and alleviated after that with the inflammatory scores of 0.5 in 30 days after injection.The histopathological score was consistent with the clinical score in the models on the 30 days.The serum IL-17 content of model mice was (0.98±0.05) ng/L before injection and increased to (51.85 ±2.42) ng/L on the fifth day,and decreased to (4.01±0.06)ng/L on the fifteen day.But,the serum IL-17 level increased to (25.00±0.94)ng/L again on the 25th day,and then lowed to (6.01 ±0.21)ng/L 30 days after injection,showing a significant elevation in comparison with that of before injection (P=0.000).The serum IFN-γ content of the model mice was (1.02±0.09)ng/L before injection and increased to (50.54±0.48) ng/L on the fifth day,and (73.21±0.12) ng/L on the tenth day,and then it declined gradually until (5.15±0.18)ng/L in the 30th day,which was still higher than that of before injection (P=0.000).After injection of IRBP+CFA,the serum TNF-α level upregulated from the second day to fifth day with the peak values (134.25±0.59)ng/L,and declined to valley on 15th day.A repeat elevation of serum TNF-α level was found on the 20th day with the values (60.54±0.62)ng/L and followed by decrease till the 30th day,which was higher than that of before injection (P=0.660).Serum IL-10 was detectable in the tenth day and peaked on the 15th day.Then a slight decrease was seen till the 30th day,compared with before injection(P =0.000).The contents of IL-10 mRNA,IL-17 mRNA,TNF-α mRNA,IFN-γmRNA in mice spleens followed the same pattern with serum levels of their proteins.Conclusions IL-17,IFN-γ,TNF-α and IL-10 are key inflammatory factors of Th1,Th2 and Th17,they present with specific changes during EAU,it confirming that IFN-γ probably play a pathogenic role in EAU,IL-17 and TNF-α levels probably associated with the chronic and recurrent procedure of uveitis,IL-10 plays an inhibit role in EAU. Key words: Uveitis/experimental autoimmune; Immune/specific autoimmune disease; T helper cell; Inflammatory factor/interleukin, interferon-γ, tumor necrosis factor-α; C57BL/6 mouse