Role of PI3-kinase in anti-helminth immunity involving IgE and gastrointestinal mast cells

我们先前已经证明，IA类磷脂酰肌醇3-激酶(PI3K)在胃肠道肥大细胞的发育和抗松材线虫的免疫中起重要作用。由于胃肠道肥大细胞和免疫球蛋白E在抗家蝇免疫中起重要作用，我们利用缺乏IA类PI3K的P85α调节亚单位的小鼠，研究了IA PI3K在胃肠道肥大细胞分化和Ig E类缝合重组中的作用。在p85α缺陷的肥大细胞中，以IL-3为增殖因子的p85α缺陷的肥大细胞的c-Kit信号显著受损，而对干细胞因子刺激的肥大细胞的JNK活性严重受损。尽管在p85α缺陷的肥大细胞中A4(37整合素)的表达是正常的，但a4137与其配体MadCAM的结合明显弱于野生型肥大细胞和p85α缺陷的肥大细胞的迁移(…检查SCF对MAdCAM-1涂层表面的亲触性也受到了更多的抑制。我们从这些观察中得出结论，p85α缺陷小鼠胃肠道肥大细胞的缺乏是由于在肠道的迁移和存活不足所致。有趣的是，蠕虫感染诱导了p85α缺陷小鼠适度的肥大细胞增多症。已知IL-3在蠕虫诱导的肥大细胞增多症中起重要作用。PI3K/IL-3双缺陷小鼠对文氏链霉菌感染的敏感性明显高于每一单缺陷小鼠，肠道肥大细胞增多，血清mMCP1的诱导严重受损。这些结果表明，IL-3的产生可能支持85a缺陷小鼠的肥大细胞增多症。我们还检测了PI3K在免疫球蛋白E产生中的作用，发现P85α缺陷小鼠产生的血清免疫球蛋白E增加。纯化的p85型α缺陷B细胞在体外对抗CD40mAb和IL-4的反应比野生型B细胞产生更多的IgE。PI3K抑制剂Wortmannin和IC87114促进抗CD40单抗和IL-4刺激的野生型B细胞产生IgE。在相同条件下，抗原受体交联以PI3K依赖的方式诱导分化抑制因子2(ID2)的表达，抑制活化诱导型胞苷脱氨酶(AID)和类开关重组(CSR)的表达。在浓缩的细胞培养条件下，IgE的产生也受到抑制，这一作用可被PI3K抑制完全逆转。CSR后，PI3K在蛋白水平选择性抑制IgE的产生。我们的结果表明，PI3K在CSR和蛋白质水平上都负向调节IgE的产生。较少

We have previously shown that class IA phosphoinositide 3-kinase (PI3K) is important in the development of gastrointestinal mast cells and anti-helminth immunity against Strongyloides venezuelensis. Since gastrointestinal mast cells as well as IgE are important in anti-henminth immunity, we examined the role of class IA PI3K in gastrointestinal mast cell differentiation and IgE class stitch recombination using mice deficient for the p85α regulatory subunit of class IA PI3K. c-Kit signal was strongly impaired in p85α-deficient mast cells established from the bone marrow with IL-3 as proliferation and JNK activation in response to SCF was severely impaired in p85α-deficient cultured mast cells. Although the expression of a4 (37 integrin that is critical for cellular migration to the intestine was normal in p85α-deficient mast cells, the binding of a4137 to its ligand, MAdCAM was significantly weaker than that of wild type mast cells and migration of p85α-deficient mast cells as examined … More by haptotaxis on MAdCAM-1 coated surface in response to SCF was also impaired. We conclude from these observations that the lack of gastrointestinal mast cells in p85α-deficient mice is due to the deficiency in both migration to and survival in the intestine. Interestingly, helminth infection induced modest mastocytosis in p85α-deficient mice. It is known that IL-3 plays an important role in helminth-induced mastocytosis. PI3K/IL-3 double deficient mice were significantly more sensitive to the infection by S. venezuelensis than each single deficient mouse line as mastocytosis in the intestine and the induction of serum mMCP1 were severely impaired in double deficient mice. These results indicate that production of IL-3 likely supports mastocytosis in 85a-deficient mice. We also examined the role of PI3K in IgE production and found that p85α-deficient mice produced increasing amounts of serum IgE. Purified p85α-deficient B cells produced more IgE than wild type B cells in vitro in response to anti-CD40 mAb and IL-4. PI3K inhibitors wortmannin and IC87114 enhanced IgE production by wild type B cells stimulated with anti-CD40 mAb and IL-4. Under the same condition, antigen receptor cross-linking induced the expression of inhibitor of differentiation-2 (Id2) and suppressed the expression of activation induced cytidine deaminase (AID) and class switch recombination(CSR) in a PI3K-dependent manner. IgE production was also suppressed in a concentrated cell culture condition, which was completely reversed by PI3K inhibition. The selective suppression of IgE production by PI3K was also observed at a protein level after CSR. Our results indicate that PI3K negatively regulates IgE production at both CSR and protein levels. Less