The Dynamic Expression Of Smad3 And Smad7 In The Experimental Autoimmune Neuritis

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 CD4+T-cell-mediated inflammatory peripheral nervous system (PNS) demyelinating disease that shares many clinical and immunological features with GBS, is an ideal animal model of GBS. Now it's generally believed that the breakdown of the immune homeostasis and the activation of autoantigen-specific T-cell play a key role during the development of EAN.Transforming growth factor-β1 is a multifunctional immuno-regulatory cytokine of TGF-βfamily, which is capable of regulating the growth and differentiation of T cells, responsible for maintaining immune homeostasis. Previous research has proved that TGF-β1 is involved in protection from EAN,which serves as an immunosuppressive factor, Recently the discovery of a set of proteins termed of Smads (Sma-and Mad-related proteins) provides extensive perspective in further research of TGF-(31 signaling, which is the central transducer of TGF-(3 signal.Smad7 is a negative regulator of TGF-P signaling, whereas Smad2 and Smad3 are the first substrate of TGF-βsignaling in the cytoplasm, the expression of Smad3 directly affects the transduction of TGF-βsignaling.Several studies indicate that abnormal expression of Smad proteins exists in some autoimmune diseases such as Inflammatory bowl disease and multiple sclerosis, accompanied with impaired TGF-β1 signaling, the dysfunction of which is associated with the pathogenesis of many kinds of autoimmune diseases.The present study is proposed to examine the dynamic expression of Smad3,Smad7 protein in the sciatic nerve of EAN rats. Our aim is to explore that whether Smad3 and Smad7 are involved in the development of EAN, and we also wish this study could contribute to the new strategy for curing the autoimmune disease.Methods 48 Lewis rats, specified-pathogens free (SPF), male, aged 6-8 weeks,160-180g, were randomly divided into four groups:NS group(n=4,4,4,4), adjuvant group(n=4,4,4,4), EAN group(n=4,4,4,4). Establishment of the EAN model:firstly, we prepare the antigen emulsion as follows:dissolve the P253-78 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), each rat in EAN group was infected with 200μL antigen emulsion, and in adjuvant group, each rat was given 200μL CFA; and The immunization was performed in the feet palm of two hind limb subcutaneously only once on the zero day.We investigated the incidence of the experimental rats, which were sacrificed respectively in 7th day,16th day,21th day and 33th day, the pathological representation of the sciatic nerve were viewed by HE stain and Weil's stain. The expressions of Smad3,Smad7 protein was detected by western blot. Results 1. During the whole course, the rats in NS group and adjuvant group did not show any manifestation, with continuously increasing body weights; compared to the NS group and adjuvant group, Rats of EAN group began to show clinical signs on the 11th day, and got a significantly higher clinical score on the 17th day, accompanied with a obvious lower weight, then gradually increased, and the clinical manifestation ameliorated obviously on the day 33th.2. Compared to the NS group and adjuvant group, Smad7 in EAN group was up-regulated even at onset(p<0.0l), especially notable during the peak(p<0.01), and then tend to descend gradually during the recovery phase.3. Compared to the NS group and adjuvant group, the expression of Smad3 in EAN group was down-regulated from onset to recovery phage (p<0.05), especially notable during the peak(p<0.01).Conclusions 1. Smad3 and Smad7 may interfere the sigal trans-duction of TGF-β1/Smad and thus play a role in the pathogenesis of EAN. Smad3 and Smad7 may become the new targets of GBS.