The Expressions Of TLR2 And TLR9 In The Experimental Allergic Neuritis And The Effects On Its Pathogenesis Made By TLR9 Antagonist

Objective Guillain-Barre Syndrome (GBS) is an autoimmune peripheral nervous system, characterized with the demyelination of peripheral nerve and inflammatory cells infiltration, whose pathogenesis is still unknown. Experimental autoimmune neuritis(EAN), an autoantigen-specific T-cell-mediated inflammatory peripheral nervous system (PNS) demyelinating disease and shares many clinical, electrophysiological and immunological features with GBS, is an ideal animal model to study the GBS, in which the imbalance of Th1 and Th2 cells plays an key role. Toll like receptors (TLRs) is a series of recently discovered pattern recognition receptor in innate immunity. It can recognize the antigen by pathogen associated molecular patterns (PAMP), and activate the antigen presenting cell(APC), producing co-stimulating molecule to activate T cells. Each TLR could recognize its peculiar PAMP origined from distinctive infectious agent. As we all know, TLR2 recognize the Gram-positive bacteria peptidoglycan, when the TLR9 discerns the DNA virus or nonmethylation CpG DNA, which is also known as CpG oligodeoxynucleotide(ODN). It has been investigated that the expression of TLR9 is up-regulated in EAN, additionally, a suppressive ODN could ameliorate the clinical symptoms of rheumatic arthritis (RA) induced by CpG ODN.In this study, the animal model of EAN was administered with this suppressive ODN, which was also called TLR9 antagonist, and the variance of clinical symptom was compared to the animals not given the ODN. Reverse transcription polymerase chain reaction(RT-PCR)was used to detected the TLR2 and TLR9 in sciatic nerve, spleen, lymphoid node and peripheral blood of EAN rats. Our aim is to explore whether there has the abnormality of TLR2, approach the specific role of TLR9 in EAN. We also wish this study could contribute to the new strategy for curing the autoimmune disease.Methods 102 Lewis rats, specified-pathogens free (SPF), male, aged 6-8 weeks, 160-180g, were randomly divided into four groups: NS group(n=6,6,6,6), adjuvant group(n=6,6,6,6), EAN group(n=6,6,6,6) and ODN intervention group(n=6,6,6,6). Additionally, we detected the fundamental level of according indicatrix before immunizing the animal. Establishment of the EAN model: firstly, we prepare the antigen emulsion as follows: dissolve the P2_53-78 with NS, and then mingle the mix with complete Freund's adjuvant (CFA) completely( the concentration of P2 is 100μg/200μL). We administered the rats in NS group with NS (200μL/per rat), which was substituted by antigen emulsion (200μL/per rat), and in adjuvant group, each rat was given 200μL CFA; and each rat in ODN intervention group was infected with 200μL antigen emulsion plus 100μg suppressive ODN. The immunization was performed in the feet palm of two hind limb subcutaneously.We investigated the incidence of the experimental rats, which were sacrificed respectively in 7^th day, 16^th day, 21^th day and33^th day, the pathological representation of the sciatic nerve were viewed by HE stain and Weil's stain. The expressions of TLR2 and TLR9 were detected by RT-PCR.Results 1. During the whole course, the rats in NS group and adjuvant group did not have overt symptom, with continuously increasing body weights; compared to the NS group and adjuvant group, the EAN group has a significantly lower weight( p<0.01), which decreased in 11^th day and fluctuated to the bottom in 17^th day and then gradually increased. The weight difference between EAN group and ODN intervention group is also significant(p<0.05), additionally, the ODN intervention group has a higher clinical scores(p<0.05); 2. compared to NS group, TLR2 in EAN group was up-regulated even in onset(p<0.05), especially during the peak(p<0.01), and then tend to descend gradually during the recovery phase, during which the TLR2 was still higher than NS group(p<0.05). The ODN intervention group has a lower TLR2 expression during onset and peak (compared to NS group, p<0.05) , and a increasing ascend during recovery phase; 3. compared to NS group, TLR9 in EAN group was up-regulated even in onset(p<0.05), especially during the peak (p<0.01), and then tend to descend gradually during the recovery phase, in which the TLR9 was still higher than NS group(p<0.05); the expression of TLR9 in ODN intervention group was lower than EAN group during each phase (p<0.05).Conclusions 1. TLR2 may play a role in the pathogenesis of EAN; 2. TLR9 participates in the induction period, to which TLR9 is critical; 3.The suppressive ODN could significantly ameliorate the clinical symptoms of EAN rats.