| Rheumatoid arthritis (RA) is a systemic autoimmune disease that mainly characterizedby chronic inflammation targeting synovial membrane, following with cartilage andbone erosion. Much B lymphocyte infiltrate into inflammatory synovium of RA. Bcell-activating factor belonging to the TNF family (BAFF) is a B cell survival andmaturation factor. BAFF bind to its receptor BAFF-R (BAFF/BAFF-R) can promote Blymphocyte proliferation and activation. PI3K/Akt/mTOR signaling pathway plays avital role in lymphocyte proliferation and survival. However, document retrievalsshowed that PI3K/Akt/mTOR pathways were almost discussed in the pathogenesis andtreatment method of malignant cancer. It is unknown whether BAFF/BAFF-R regulatesB cell proliferation and survival in RA through PI3K/Akt/mTOR pathways. Paeoniflorin(Pae) is one of the principal bioactive components of total glucosides of paeony (TGP)and TGP was extracted from the root of Paeonia lactiflora. It has been widely used inthe treatment of inflammatory disorder in traditional Chinese medicine. The research inour lab showed that TGP reduced cytokine levels, regulated Bcl-2, Bax expression ofFLS, and macrophage of animal models for RA. Pae has anti-inflammatory effects oncollagen-induced arthritis (CIA) rats by modulating abnormal G protein-coupledsignaling and Ras-MAPK signal pathway, which may be one of the mechanismsunderlying its inhibition of synovitis. Pae also inhibited the fuction of B lymphocytes byreducing anti-type II collagen antibody in serum of rats with CIA. But it is not clearwhether Pae regulate B cell activation via PI3K/Akt/mTOR signaling pathway mediatedby BAFF/BAFF-R. OBJECTIVETo investigate BAFF/BAFF-R up-regulates B lymphocyte function of rats with CIA viaPI3K-Akt-mTOR signaling and the regulation of pae.METHODSThe rats with CIA were randomly separated into different groups and treated with Pae(25,100mg/kg) once per day from day18to38after immunization. The effects of Paeon CIA rats were evaluated by arthritis scores, paw swelling, joints and spleenshistopathology and indices of spleen and thymus. Concentrations of BAFF, anti-CIIantibody, IgA, IgG and IgM in CIA rats serum were measured by Enzyme-linkedimmunosorbent assay (ELISA) kits. Total protein expression of BAFF-R, P110δ,P-Akt1/2/3and mTORC1(Raptor (10E10)) were measured by Immunohistochemistryand Western blotting. The effects of Pae to splenic lymphocytes by vitro proliferationexperiment and the rate of flow cell apoptosis.RESULTS1The function change of B lymphocyte in CIA rats and the regulation of Pae.From day18after immunization, CIA rats joint synovial hyperplasia were reached4~5layers, cell infiltration obviously, pannus and cartilage erosion seriously. In CIA ratsspleens, white pulp proliferated, germinal centers expansion, red pulp hyperemia andspleens were infiltrated with inflammatory cells. Enzyme-linked immunosorbent assay(ELISA) results showed that concentrations of immunoglobulin (Ig) A, IgM, IgG,BAFF and anti-CII antibody in CIA rats obviously increased compared with normal rats.The results show that B lymphocyte function of CIA rats abnormal increased. Theadministration of Pae (25and100mg/kg) varying degrees diminished theseabnormalities. Pae(100mg/kg) obviously decreased CIA rats arthritis score, alleviatedCIA rats paw swolling, decreased spleen index and alleviated histopathological manifestation; inhibited expression of IgA, IgM, IgG and anti-CII antibody in CIA rats.The correlation analysis shows that the level of BAFF, IgA, anti-CII antibody wererelated to the arthritis score. The results point out the therapeutic action of Pae wasrelated to the function of B lymphocyte.2The concentration of BAFF in serum and BAFF-R in B lymphocyte and the effects ofPae.The concentration of BAFF in serum was increase compared with the normal group.The IHC showed BAFF-R was expressed in the mantle zone (MC) and marginal zone(MZ) in the spleen. Compared with mantle zone and marginal zone, the expression levelof BAFF-R was lower in the germinal center (GC). Pae could reduce BAFF andBAFF-R expression level. These results showed that the function of Pae was related tothe down regulate of BAFF and BAFF-R expression.3The change of PI3K/Akt/mTOR signaling pathway in B lymphocyte and theregulation of Pae.Immunohistochemical and Western blotting analysis results showed that expressionlevel of P110δ, P-Akt1/2/3and mTORC1(Raptor (10E10)) in CIA rats significantlyincreased. Pae could decrease the level of P110δ, P-Akt1/2/3and mTORC1.The resultsshowed that up-regulation of PI3K/Akt/mTOR signaling pathway could promote thecell proliferation. Pae could regulate B lymphocyte function via PI3K/Akt/mTORsignaling pathway.4The effect of BAFF or IGF-1on the proliferation and apoptosis of B lymphocyte invitro the regulation of Pae.The proliferation experiment result in vitro showed that B lymphocyte proliferationobviously and the rate of apoptosis decreased. Pae (10-4,10-5mol/L) could restrain BAFF or IGF-1stimulated cell proliferation, increase cell apoptosis. These resultssuggested that BAFF and PI3K had direct effect to B lymphocyte proliferation andsurvival. BAFF/BAFF-R might mediate PI3K/Akt/mTOR signal pathway activation toupregulated B lymphocyte proliferation and survival and Pae might inhibitPI3K/Akt/mTOR mediated by BAFF/BAFF-R to block B lymphocyte proliferation andsurvival.CONCLUSIONS1PI3K-Akt-mTOR signaling might mediate by BAFF/BAFF-R activation to upregulateB lymphocyte function.2The effect of Pae may be via BAFF/BAFF-R involved in PI3K/Akt/mTOR signalingpathway, this may be one of the therapeutic actions of Pae. |
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