Ménoret Antoine, Myers Lara M, Lee Seung-Joo, Mittler Robert S, Rossi Robert J, Vella Anthony T
Department of Immunology, University of Connecticut Health Center, Farmington, CT 06032, USA.
J Immunol. 2006 Nov 1;177(9):6091-7. doi: 10.4049/jimmunol.177.9.6091.
In general, TGFbeta is synthesized as a procytokine that requires proteolytic activation, release of the mature cytokine from its noncovalently associated latent-associated peptide, and binding to TGFbetaRII to mediate suppressive activity. We tracked this process in mice containing primed CD8 regulatory T cells (Tregs) by immunoblotting in primary whole cell lysates for pro-TGFbeta, latent-associated peptide and mature TGFbeta. Generation of CD8 Tregs promoted processing of the 50 kDa pro-TGFbeta protein into a 12.5 kDa mature TGFbeta species in vivo. Despite the inability to detect mature TGFbeta in the sera of mice with primed CD8 Tregs and in the synthetic culture medium of stimulated CD8 Tregs, we demonstrated engagement of TGFbetaRII through immunoblotting for Smad2 phosphorylation. This process relied on continual TCR triggering, which also induced Smad3 phosphorylation. To understand the movement of mature TGFbeta, we showed that in contrast to IFN-gamma, mature TGFbeta does not remain a soluble cytokine but is likely to be rapidly adsorbed by neighboring cells. These data show the exquisite local control directed toward TGFbeta by the immune system and underscore the fine specificity involved in its detection.
一般来说，转化生长因子β（TGFβ）作为一种前细胞因子合成，需要蛋白水解激活，从其非共价结合的潜伏相关肽中释放成熟细胞因子，并与TGFβRII结合以介导抑制活性。我们通过对原代全细胞裂解物中的前TGFβ、潜伏相关肽和成熟TGFβ进行免疫印迹，在含有预致敏CD8调节性T细胞（Tregs）的小鼠中追踪了这一过程。CD8 Tregs的产生促进了50 kDa前TGFβ蛋白在体内加工成12.5 kDa的成熟TGFβ。尽管在预致敏CD8 Tregs的小鼠血清和刺激的CD8 Tregs的合成培养基中无法检测到成熟TGFβ，但我们通过对Smad2磷酸化进行免疫印迹证明了TGFβRII的参与。这一过程依赖于持续的TCR触发，这也诱导了Smad3磷酸化。为了了解成熟TGFβ的移动，我们发现与干扰素-γ不同，成熟TGFβ不会保持为可溶性细胞因子，而是可能会被邻近细胞迅速吸附。这些数据显示了免疫系统对TGFβ的精确局部控制，并强调了其检测中涉及的精细特异性。
