| Backgroud:Systemic lupus erythematosus is a systemic autoimmune disease that can affect any part of the body. In genetically predisposed subjects, environmental factors, such as ultraviolet light, infection and drugs, induce the breakdown of self-tolerance and lead to recruitment, activation and expansion of autoreactive lymphocytes. This cascade culminated with disease-specific autoantibody production by B cells, causes an autoimmune reaction and eventually leads to tissues damage. Activated B cells produce large amounts of antibodies against the different types of nucleic acid structure, including antinuclear antibodies, anti-double-stranded DNA antibodies, anti-single-stranded DNA antibodies, anti-Sm antibodies and a variety of other anti-cellular components antibodies. These autoantibodies combine with the corresponding antigens in vivo and form antibody immune complexes, which can deposit in the skin, blood vessels, kidneys, nervous system and so on, and then activate complements and damage tissues and organs. Some antibodies combine with the specific surface antigens of erythrocytes, platelets, etc., causing hemolytic anemia and thrombocytopenia.Exact etiologies and pathogenesis of SLE is still not very clear, a large number of autoantibodies produced by B cells in SLE may be just an end stage, rather than initiating factor. The current study of the pathogenesis of SLE more concentrated on the following areas:Aberrant apoptosis:Apoptosis process produced many modified autoantigens, which is conducive to the removal of the phagocytic cells, but also enhances the immunogenicity of the autoantigen and provides a basis for the production of autoantibodies and autoimmune diseases.In patients with SLE, several abnormalities have been found that can result in insufficient clearance of apoptotic materials, such as decreased clearance of phagocytic cells and complement defects. Insufficient clearance of apoptotic materials can lead to accumulation of apoptosis substances in the tissues, A large number of modified or hidden autoantigens release and activate DCs, which present antigens to Th cells, and then activate autoreactive B cells, which produce large amounts of autoantibodies and form a vicious cycle.Aberrant DCs:Dendritic cells, the most powerful professional antigen-presenting cells, which can activate naive T-cells, induce immune tolerance, trigger a strong immune response, participate in the mediation of immune response and play an important role in both innate and adaptive immunity. A large number of studies have confirmed that toll-like receptors, Fey receptors and type I interferon of DCs have been related to the induction and the disease severity of SLE.Aberrant Th cells:changes in T cell homeostasis play a key role in the development of the disease. T cells are critical drivers of the B-cell-dependent autoantibody response through provision of co-stimulatory signals and cytokines. Overactivation of effector T cells, such as Thl, Th2and Th17cells, causes a variety of inflammatory responses. On the other hand, the immune system has a complete immunoregulary function, which is dominated by Th cells, particularly regulatory T cells. Effective immunologic homeostasis relies on a balance between helper T cell activation and regulatory T cell suppression. When homeostasis is disrupted and the immune system is conducive to activation, the host will become susceptible to autoimmunity.Th cells can be divided into Thl, Th2, Th17and Treg cells, based on their functions and the cytokines they primarily produced. Thl cells, which secrete IFN-y and IL-2, enhance cellular immunity, mediate late phase hypersensitivity and promote inflammation. Th2cells secrete IL-4, IL-5and IL-13which characteristically enhance humoral immunity and play a significant role in allergy and anti-parasitic infections. The differentiation of Th17cells is initiated by TGF-β and IL-6, which mainly secrete IL-17and involved in autoimmune diseases and inflammatory reactions. Under the action of TGF-β,Th cells differentiate into Treg cells which express Foxp3and secrete TGF-β, involving in induction of immune tolerance and immune regulation. The differences in the function of Thl, Th2, Th17and Treg cells are often decided by their specific cytokines and transcription factors.In recent years, with a deeper understanding of Th17cells and Treg cells, more and more evidences show that Thl7and Treg cells may play a more critical role in autoimmune diseases such as SLE. Both patients with SLE and lupus animal models exist imbalance of ratio between Th17and Treg cell.IL-17, mainly produced by Th17cells, can induce many types of cells to produce inflammatory cytokines and chemokines and recruit neutrophils. IL-17also induces angiogenesis, triggers and maintains the inflammatory response. IL-17is a proinflammatory cytokine, which is closely related to the occurrence and development of many autoimmune diseases.High expression of IL-17had been found in multiple sclerosis, rheumatoid arthritis, psoriasis and other diseases.Regulatory T cells have immunomodulatory function, which are essential to maintain immune homeostasis and are critical regulators for a variety of immune responses. They play an important role in autoimmune diseases, cancers and graft-versus-host diseases. The transcription factor Foxp3was identified as a master regulator for the development and function of Treg cells. Downregulation of Foxp3will result in the absence of Treg cell function. Treg cells are able to suppress autoreactive T and B lymphocyte activation and cytokine secretion.They can also induce self-tolerance and prevent from autoimmune diseases, hypersensitivity and inflammation. The absence of Treg cell function has been linked to many autoimmune diseases.Imbalance between pro-inflammatory Th17cells and protective Treg cells may exist in SLE, which leads to excessive activation of Th17cells and down-regulation of Treg cells, and finally induces immune response.The abnormalities in the number or function of Th17and Treg cells whose differentiation are co-regulated by TGF-β and IL-6may play a key role in the pathogenesis of SLE.Animal model is an important tool to study etiology, pathogenesis, and treatment of human diseases.Lupus mice model is widely used to study the pathogenesis and treatment of systemic lupus erythematosus,of which MRL/lpr lupus model rat is one of common SLE animal models.In MRL/lpr mice, an autoimmune syndrome develops spontaneously that closely resembles human systemic lupus erythematosus and is characterized by the production of various autoantibodies and the development of fatal glomerulonephritis. Disease begins as early as8weeks of age in these mice, with the presence of detectable serum autoantibodies. Pronounced lymphadenopathy is observed at12weeks of age, By12-16weeks of age, MRL/lpr mices begin to produce a variety of autoantibodies, including anti-double-stranded DNA antibodies. From16weeks of age to24weeks of age, immune complex-mediated proliferative glomerulonephritis, vasculitis, arthritis, and massive lymphadenopathy will develop in these MRL/lpr mices; only50%of the mice will survive until24weeks of age. A steady deterioration of renal function manifesting as severe proteinuria begins at approximately16weeks of age.Clinical drugs and methods commonly used in the treatment of SLE mainly have corticosteroids, immunosuppressive agents, biological agents, Intravenous immunoglobulins and hematopoietic stem cell transplantation. Despite SLE treatment has made great achievements in several decades and the survival rate of patients with SLE was significantly improved, There is no special ideal drugs and treatment methods, current research is being geared towards finding a possible cause, a cure, and more effective treatment plans to extend and increase the quality of life for lupus patients. Chinese herbal medicine is a treasure of traditional Chinese medicine, part of which plays its immunomodulatory effects on autoimmune diseases in multiple links and also has lower side effects and the lower recurrence rate. So it shows unique application prospects in autoimmune diseases, especially in SLE. TGP is a group of glycoside substances,extracted from the dry roots of herbaceous peony, More than90%of total glucosides is paeoniflorin, which is the main effective components.Clinical application and pharmacology study found that TGP has multiple ways to suppress autoimmune response. It also has anti-inflammatory, analgesic, immunoregulatory and antioxidative actions without evident toxic or side effects. So it is widely used in a variety of autoimmune diseases such as rheumatoid arthritis, SLE and ankylosing spondylitis.TGP play an important role in the treatment of systemic lupus erythematosus, which can reduce inflammation and ameliorate lupus condition, but its mechanism in SLE remains unclear, whether TGP plays a protective role in the treatment of SLE by adjusting imbalance between Treg and Th17cell still need to been further explored. In this study, quantitative real-time polymerase chain reaction was used determine the changes in IL-17and Foxp3expression of the peripheral blood of mice after treatment with TGP, and then analysis correlation between TGP treatment and imbalance of Treg and Th17cells to deeply understand the possible mechanism of systemic lupus erythematosus and to provide important theoretical and experimental evidence for better clinical application of TGP.Objective:To observe the effects of TGP on urine protein content, anti-ds-DNA antibodies level and expression of IL-17, Foxp3mRNA in peripheral blood of MRL/lpr mice.Methods:According to body weight, twenty famale MRL/lpr mices were randomly divided into three groups:high-dose TGP group, low-dose TGP group and control group. According to"between human and animal body surface area ratio of equivalent dose conversion table"and the routine dose of TGP, high-dose group was given TGP (121mg/kg) by intragastric administration once a day for30consecutive days; Low-dose group was given TGP (81mg/kg) by intragastric administration once a day for30consecutive days; control group was given pure water. Collected24h-urine at a fixed time(before,2,4weeks) with metablic cages. Urinary protein content was detected using the method of coomassie brilliant blue. Collected blood samples at a fixed time (before,2,4weeks).The levels of antibodies were measured by enzyme-linked immunosorbent assay(ELISA). All mices were sacrificed after four weeks,and peripheral blood was collected.Expression of IL-17、Foxp3mRNA in peripheral blood of MRL/lpr mice were detected by real-time fluorescent quantitative reverse transcriptase polymerase chain reaction.Results:1.General conditions:Feeding, behavior and the hair were normal in three groups before the treatment. With the passage of time the mice of control group gradsually appeared mental burnout, settled, the reduction of feeding times and activities, and decreases of hair gloss. high-dose and low-dose groups had no obvious change, only hair gloss decline compared with the previous; mouth, eyes, ears and nose had no abnormal secretions; stooland urine output was normal. At the end of the experiment there were no deaths.2.Urinary protein content:At pre-administration,2weeks after administration, the difference in the three groups was no statistically significant(P>0.05); At4weeks after administration, as compared with control group, urinary protein content in the high-dose and low-dose groups decreased significantly(P<0.05; P<0.05), compared with low-dose TGP group, high-doseTGP group decreased significantly(P<0.01).3.The level of anti-ds-DNA antibody:At pre-administration,2,4weeks after administration, the difference in the three groups was no statistically significant(P>0.05); At4weeks after administration, as compared with control group, urinary protein content in the high-dose and low-dose TGP groups increased significantly(P<0.01; P<0.01), the difference in the high-dose and low-dose TGP groups was no statistically significant(P>0.05);4. The expression of IL-17、Foxp3mRNA in peripheral blood of MRL/lpr mice: At4weeks after administration, the expression of Foxp3mRNA in the three groups was no statistically significant(P>0.05); As compared with control group, expression of IL-17mRNA in the high-dose and low-dose TGP groups decreased significantly(P <0.05; P<0.05), compared with low-dose TGP group, expression of IL-17 mRNA in high-dose TGP group decreased significantly(P<0.05).Conclusion:TGP can reduce the urinary protein content and has a role of delaying the progress of the disease and protect the kidneys, but it increases the anti-ds-DNA antibody levels. It may play its role by down-regulating IL-17and then regulating Thl7/Treg balance. |
PDF Full Text Request