ABSTRACT
ObjectiveTo investigate the intervention effect of total glucosides of paeony （TGP） on the renal injury of MRL/lpr mice based on the Toll-like receptor 9 （TLR9）/myeloid differentiation factor 88 （MyD88）/nuclear transcription factor-κB （NF-κB） signaling pathway and explore the immunological mechanism of TGP in preventing and treating systemic lupus erythematosus （SLE）. MethodMRL/lpr female mice of SPF grade were randomly divided into a model group， a dexamethasone group （0.15 g·kg-1）， and high- （0.078 g·kg-1） and low-dose （0.039 g·kg-1） TGP groups， and female C57BL/6J mice were assigned to a blank group， with 7 mice in each group. Mice in each group were treated with corresponding drugs or normal saline by gavage at the same time every day. After 4 weeks， samples were collected. The kidney and spleen were weighed， and the organ index was calculated. Serum creatinine （SCr） and blood urea nitrogen （BUN） levels in each group were detected by biochemical assay. Hematoxylin-eosin （HE） staining was used to observe the histopathological changes in the kidney. The degree of renal fibrosis was evaluated by Masson staining. The serum levels of interleukin （IL）-2， interferon （IFN）-α， IL-4， and anti-nuclear antibody （ANA） were detected by enzyme-linked immunosorbent assay （ELISA）. The mRNA expression of TLR9， MyD88， and NF-κB p65 in renal tissues was detected by real-time quantitative polymerase chain reaction （Real-time PCR）. The protein expression of TLR9 and NF-κB p65 in renal tissues was detected by immunofluorescence. The protein expression of TLR9， MyD88， and NF-κB p65 in renal and spleen tissues was tested by Western blot. ResultCompared with the blank group， the model group showed increased SCr， BUN， spleen index， and kidney index （P<0.05）， deteriorated pathological injury and fibrosis in renal tissues， elevated serum levels of IFN-α， IL-4， and ANA， decreased level of IL-2 （P<0.05）， and up-regulated TLR9， MyD88， and NF-κB p65 mRNA and protein levels in the kidney and spleen （P<0.05）. Compared with the model group， the TGP groups displayed reduced SCr， BUN， spleen index， and kidney index （P<0.05）， relieved pathological damage and fibrosis in renal tissues， decreased serum levels of IFN-α， IL-4， and ANA （P<0.05）， increased level of IL-2， and declining mRNA and protein expression levels of TLR9， MyD88， and NF-κB p65 in the kidney and spleen （P<0.05）. ConclusionTGP may inhibit the expression of downstream inflammatory factors to regulate immunity and resist SLE-induced renal injury by regulating the TLR9/MyD88/NF-κB signaling pathway.