CERAMIDE,APOPTOSIS-INDUCING SECOND-MESSENGER,USED IN THE TREATMENT OF LUPUS-PRONE MODEL MICE

在与Fas配体连接后，细胞表面Fas在淋巴细胞中传递凋亡信号，而cerarnide被认为是该途径中的第二信使。我们去年报道，口服一种与神经酰胺具有非常密切结构相似性的新型免疫抑制剂FTY 72 O，成功地改善了肾小球肾炎，并延长了狼疮性MRL-lpr/lpr小鼠的存活率。因此，本研究的目的是探讨口服神经酰胺本身能否用于MRL-lpr/lpr小鼠的治疗。由于长侧链的神经酰胺在体外不能穿透细胞膜并诱导细胞凋亡，因此本研究选择了具有细胞渗透性的C2-神经酰胺。将溶解在橄榄油中的2 mg/kg体重的C2-神经酰胺每周三次口服给予15只4月龄的MRL-lpr/lpr小鼠。相同数量的MRL-lpr/lpr小鼠接受单独的橄榄油作为阴性对照或地塞米松（2 mg/kg）作为阳性对照用于治疗。在8月龄时，用C2-神经酰胺处理的MRL-lpr/lpr小鼠表现出较长的存活曲线，具有CD^&lt;3+&gt;CD^&lt;3+&gt;CD^&lt;4 + T细胞表型的数量减少<4-><8->，并且血清抗DNA抗体水平低于单独用橄榄油处理的小鼠。这些参数均具有统计学意义。C2-神经酰胺组小鼠肾小球IgG沉积量远低于橄榄油组。口服C2-神经酰胺引起的这些改善的水平与地塞米松引起的几乎相当。C2-神经酰胺作为一种副作用小的治疗方案，值得进一步研究。

Upon ligation with Fas-ligand, cell-surface Fas transmits apoptosis-signals in lymphocytes and cerarnide is considered to act as a second messenger in this pathway. We reported last year that oral administration of a novel immunosuppressant FTY72O, which has a very close structural similarity with ceramide, successfully improved glomerulonephritis and prolonged survival rates of lupusprone MRL-lpr/lpr mice. The purpose of the study this year, therefore, is to examine whether ceramide itself could be used for treatment of MRL-lpr/lpr mice when administered orally.Because ceramides with long side-chains can not penetrate cell membranes and induce apoptosis in vitro, we selected cell-permeable C2-ceramide in this study. Two mgfkg body weight of C2-ceramide dissolved in olive-oil were administered orally three times a week to 15 MRL-lpr/lpr mice of 4-month old. The same number of MRL-lpr/lpr mice was received either olive-oil alone as a negative control or dexamethasone (2 mg/kg) as a positive control for treatment. Anti-DNA antibody titer in sera, survival curve and renal pathology were examined for the efficacy of the treatments.At the age of eight months, MRL-lpr/lpr mice treated with C2-ceramide showed a longer survival curve, decreased number of T cells with a CD^<3+>CD^<4->CD^<8-> phenotype, and a lower level of serum anti-DNA antibody than those treated with olive-oil alone. These parameters were all statistically signficant. IgG deposited in glomeruli from mice treated with C2-ceramide was far less than that from mice administered with olive-oil alone. Level of these mprovements induced by oral C2-ceramide was almost comparable with that induced by dexamethasone. Liver damage and hyperglycemia which were desasterous side-effects of systemic anti-Fas antibody and dexamethasone administration, respectively, were not observed.C2-ceramide seems to deserve further attention for a possible therapeutic regimen with less side-effect.