| Systemic lupus erythematosus (SLE) is a chronic, multisystem autoimmune disease with unclear pathogenesis, which can not be cured by regular medicine therapy. As the bone marrow transplant developing, the idea, which SLE is a stem cell disease, is rising. In SLE patients, in vitro bone marrow colony-forming units of granulocytes/ macrophages (CFU-GM), colony-forming units of erythroid (CFU-E), colony-forming units of megakaryocytes (CFU-MK) are decreased. These abnormalities partially come from autoantibodies, abnormalities of hematopoietic microenvironment, and inhibition from lymphocytes, but the dysfunctions of hematopoietic stem cell or progenitor cell may play the core roles. By now, there are some studies on the SLE hematopoietic stem cells or progenitor cells, but most of them focus on granulocytes/ macrophages system, few of them are on erythroid, megakaryocytes and the proliferation and differentiation of B cells in SLE bone marrow. So there are not enough evidences for SLE being a stem cell disease. To verify that SLE is stem cell disease, we employed male BXSB mice as an animal model of SLE to study the CFU-GM, CFU-E, CFU-MK of the bone marrow mononuclear cells (BMMC) by the cultured in vitro with methylcellulose semisolid culture system. The regulation of BXSB bone marrow stromal cells on CFU-GM formation was studied. The differentiation antigens of B cells and the expression of stem cell antigen-1 (Sca-1) of BMMC ware obtained by flow cytometric analysis. The above items ware obtained again after a three-week treatment with dexamethasone (1mg/kg/d) or cyclophosphamide (CTX) (20mg/kg/d) injected i.p. Sterilized saline injection i.p. used as controls. We also tested the expression of CD10, CD19, CD20, CD21, CD23, CD138, sIgG, sIgM and sIgG on the peripheral blood mononuclear cell (PBMC) from SLE patients. The following results were obtained by contrastive studies of normal mice and lupus mice, different ages lupus mice (disease onset or not), before and after therapy, in vitro and in vivo of mice, in vitro of patients: 1. Colony forming of the bone marrow of male BXSB mice with different ages : The CFU-GM counts of 8-week old male BXSB mice were significantly higher compared with those of 4-week-old male BXSB mice (P<0.05), and increased progressively in older BXSB mice, the counts reached (146.00±19.504)/2×105BMMC in 20-week old mice. There were no significant difference in CFU-GM counts between 4-week old BXSB mice and C57 mice(P>0.05). The counts of CFU-E and CFU-MK reached significant high levels in 16-week old BXSB mice. There no significant difference amonge 4-week, 8-week, 12-week old male BXSB mice and C57 mice (P>0.05). 2. Influence of bone marrow stromal cells on CFU-GM: The bone marrow stromal cells from male BXSB mice and C57 mice can stimulated theformation of BMMC CFU-GM without granulocytes/ macrophages colony stimulating factor (GM-CSF) in vitro. The CFU-GM counts in culture system with GM-CSF and stromal cells are more than that with stomal cells only, but less than that with GM-CSF only. Stromal cells from BXSB and C57 mice have the same ability to regulate CFU-GM formation. 3. Analysis of B cell differentiation antigen of male BXSB mice: The numbers of CD19+ cells, CD19+CD25+cells, CD19+CD22+ cells and CD38+ cells are all higher in 12-week, 20-week old male BXSB mice than those in 4-week old mice. That is, the hyperproliferation of B cells in BXSB mice marrow begun from the pre-B cell (CD25+), and the abnormality of B cells may exist in the pro-B cell or stem cell. 4. Changes in urinary protein content and spleen index: The urinary protein concentration is (2.919±0.529) mg/ml in saline treated mice, but in the dexamethasone and CTX group the urinary protein concentration is(2.312±0.260)mg/ml and (2.139±0.392)mg/ml respectively,and is significantly lower than the saline treated group (P<0.05). The concentration of urinary protein of dexamethasone and CTX treated mice does not decrease to the levels of 4-week old BXSB mice. The spleen index of saline treated mice is (112.3±15.7)mg/10g body weight, but in the dexamethasone and CTX group, the spleen index is (90.5±10.4)mg/10g body weight and (70.8±9.7)mg/10g body weight respectively, and is significantly lower than the saline treated group. The spleen index of dexamethasone and CTX treated mice does not decrease to the level of 4-week old BXSB mice: (35.5±5.4)mg/10g body weight. 5. Colonies forming after dexamethasone and CTX treatment: At the end of 3 weeks treatment of dexamethasone, the numbers of CFU-GM, CFU-Eand CFU-MK decreased significantly than that of saline treated group ( P<0.01,P<0.05,P<0.05, respectively), but, the CFU-GM and CFU-MK are still higher than that of 4-week old BXSB mice(P<0.01,P<0.05 respectively). In the CTX group, the numbers of CFU-GM, CFU-E and CFU-MK decreased more significantly, even became lower than that of saline group. 6. Changes of bone marrow B cell differentiation after treatment: The percentage of CD19+ cells, CD19+ CD25+cells, CD19+CD22+ cells and CD38+ cells in the BMMC of dexamethasone and CTX treated mice decreased significantly than that of saline treated group, but remain higher than that of 4-week old BXSB mice. 7. Changes of stem cell antigen (Sca-1) after treatment: There is no significant difference among the different age male BXSB mice. After 3 weeks of treatment, only the percentage of Sca-1+ cells in the BMMC from CTX treated group decreased slightly, but did not reached statistic significance (P>0.05). 8. The expression of B cell differentiation antigens on the PBMC of SLE patients: The expression of CD19, CD20, sIgM and sIgG on the PBMC of SLE patients is not different from that of normal controls significantly. The expression of CD10, CD23, CD138 and sIgD on the active SLE PBMC is higher than that of normal controls, but the expression of CD21 is lower in SLE patients than in normal controls. Conclusions from the above results: The three lines of colony forming units, the numbers of pan-B cells, B cells from pre-B to early plasma cells are all increased in aged male BXSB mice, these changes correlate with the disease of the mice closely. The treatment with dexamethasone and CTX can improve...
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