Clarification of the protective mechanisms of pregnancy to the phenotype of saposin A deficient mice, mouse model for a late-onset, chronic form of globoid cell leukodystrophy

我们通过将突变(C106F)引入鞘磷脂激活蛋白基因(丙皂苷)的皂苷A结构域，为迟发性、慢性形式的球状细胞白质营养不良症(GLD，Krabbe病)建立了一种新的小鼠模型。最有趣的是，我们发现怀孕的皂苷A缺乏(sap A^&lt；1/1&gt；)小鼠的临床和病理有显著改善。我们还发现，补充高水平的雌激素(17β-雌二醇)可以在很大程度上复制sap-A^&lt；-/-&gt；小鼠的怀孕现象。基于这些证据，我们假设怀孕期间雌激素等较高的女性性激素可以抑制小胶质细胞或巨噬细胞的激活，并防止它们在SAP-A^&lt；-/-&gt；小鼠脱髓鞘的脑损伤中产生有害分子。为了评估IBIS假说，我们分析了性别、怀孕或女性单独补充对sap-A^&lt；-/-&gt；小鼠脑内可变细胞因子和细胞因子受体mRNA表达的可能影响。然后我们发现SAP-A^&lt；/-&gt；小鼠大脑中的趋化因子和细胞因子显著上调，尤其是RANTES、MIP-1β、MIP-1α、MIP-2、MCP-1辅助的肿瘤坏死因子-α。RANTES、MIP-1、α、MIP-2和MCP-1在雌性或妊娠小鼠脑内的表达均受到抑制。对于趋化因子/细胞因子受体，我们发现在sap-A^&lt；-/-&gt；小鼠的辫子中，肿瘤坏死因子-α受体，包括TNFR2和TNFR1R，都有较高的表达。我们还发现，在怀孕的雌性SAP-A^&lt；-/-&gt；小鼠中，TNFR2的表达减少。这些结果提示妊娠对SAP-A^&lt；-/-&gt；小鼠脱髓鞘脑损伤有抗炎作用。为了进一步评估怀孕和17β-雌二醇治疗的效果，我们将利用基因芯片来阐明sap-A^&lt；-/-&gt；小鼠大脑中基因表达的整体模式。这一方法将拾取免疫相关基因以外的未知基因，并确定妊娠在脱髓鞘疾病中的保护机制。

We have generated a new mouse model for a late-onset, chronic form of globoid cell leukodysirophy (GLD, Krabbe disease), by introducing a mutation (C106F) into the saposin A domain of the sphingolipid activator protein gene (prosaposin). Most interestingly, we found significant clinical and pathological improvements in the pregnant saposin A deficient (sap A^<1/1>) mice. We also found that high level of estrogen (17β-estrdiol) supplementation could substantially duplicate the phenomena of pregnancy in sap-A^<-/-> mice. Based on these evidences, we hypothesize that higher female sex hormones such as estrogen during pregnancy can suppress the activation of microglia or macrophages and prevent them producing detrimental molecules in the demyelinating brain lesions of sap-A^<-/->mice. To evaluate ibis hypothesis, we analyzed the possible effect of gender, pregnancy or female sex hor lone supplementation to the mRNA expression of variable cytokines and cytokine receptors in the brain of sap-A^<-/-> mice. Then we found dramatic upregulation of chemokines and cytokines in the brain of sap-A^</-> mice, especially on Rantes, MIP-1β, MIP-1α, MIP-2, MCP-1 aid TNF-α. These upregulations of Rantes, MIP-1(3, MIP-1α, MIP-2 and MCP-1 were suppressed in female or pregnant sap-A^<-/-> mice brain. For chemokine/ cytokine receptors, we found higher expression of TNF-α receptors, both TNFR2 and TNFR1, in the braid of sap-A^<-/-> mice. We also found a reduced expression of TNFR2 in the pregnant female sap-A^<-/-> mice. These results suggest the anti-inflammatory effect of pregnancy to the demyelinating brain lesions of sap-A^<-/-> mice. To further evaluate the effect of pregnancy and 17β-estradiol treatment, we are going to utilize DNA microarrays to elucidate global patterns of gene expression in the brain of sap-A^<-/-> mice. This approach would pickup the unknown gene other than the immune related genes and play define the protective mechanism of pregnancy in the demyelinating disease