Optimizing mesenchymal stem cell and Treg immunosuppression for controlling SLE

 描述（由申请人提供）：间充质干细胞（MSC）作为一种生物疗法，在小鼠SLE模型和SLE患者的初步试验中可以抑制疾病，已经获得了越来越多的希望。然而，人体试验中有效性的主要局限性在于， 它们的有益作用（SLEDAI评分和蛋白尿）是部分的并且是短暂的。虽然MSC在很大程度上通过诱导Foxp 3 + T调节细胞（iTcls）发挥其免疫抑制作用，但其免疫抑制与Treg免疫抑制的关系尚未阐明。此外，如何延长MSC的免疫抑制和维持它们产生的长期T细胞仍然是未知的。 我们最近的工作发现，在Th 1和Th 17细胞活化中一个以前未被认识的事件是树突状细胞（DC）-CD 4+细胞伴侣内源性产生C3 a和C5 a，并上调其表面C3 a和C5 a受体（C3 aR/C5 aR）G蛋白偶联受体（GPCR）的表达。局部C3 a和C5 a连接相互作用的DC-CD 4+细胞配偶体上上调的C3 aR和C5 aR。我们发现，这种GPCR信号不仅提供了共刺激，而且还提供了生存信号，这些信号是Th 1和Th 17细胞应答的组成部分。重要的是，我们最近发表的工作表明，C3 aR/C5 aR信号传导进入幼稚CD 4+细胞的缺失使得自身诱导的TGF-β信号传导能够抑制CD 4+细胞CD 40 L上调和IL-6产生，并导致TGF-β的产生。这些发现的一个重要临床结果是，相比之下，过去难以产生发挥强大抑制活性且稳定的人THBE，我们的发现现在提供了实现这一目标的途径。与SLE密切相关，我们的初步研究表明，B细胞中C3 aR/C5 aR信号传导缺失，消除了CD 40上调和IL-6产生，减少了Ab产生和类别转换重组（CSR），并抑制了TLR信号传导。与此一致，我们发现破坏C3 aR/C5 aR信号传导实际上消除了降植烷诱导的鼠SLE模型中的疾病。 与CD 4+细胞和DC一样，MSC表达C3 aR/C5 aR。在未发表的工作中，我们已经发现，破坏C3 aR/C5 aR信号传导到Treg中可维持Treg在体内的稳定性>7个月。此外，我们还开发了精确定量破坏的C3 aR/C5 aR信号传导对MSC稳定性的影响的方法，并评估了MSC与体内TCFs的相互作用。这项提议的核心是我们实验室与MSC生物学先驱Arnold Caplan的合作。目的在于最佳地利用MSC和Treg免疫抑制来控制SLE。这项独特的合作将与利用我们的新型小鼠品系的小鼠SLE模型和利用我们对人类Treg谱系承诺的新见解的SLE患者进行。

 DESCRIPTION (provided by applicant): Mesenchymal stem cells (MSCs) have been gaining increasing promise as a biotherapy that can suppress disease in murine SLE models and in an initial trial of SLE patients. Major limitations of efficacy in the human trial, however, were that their beneficial effects (SLEDAI scores and proteinuria) were partial and were short lived. While MSCs exert their immunosuppressive effects in large part via the induction of Foxp3+ T regulatory cells (iTregs), the relationship of their immunosuppression to that of Treg immunosuppression has not been clarified. Moreover, how to prolong MSC immunosuppression and sustain the Tregs they produce long term remains unknown. Our recent work found that a previously unrecognized event in Th1 and Th17 cell activation is that dendritic cell (DC)-CD4+ cell partners endogenously produce C3a and C5a and up-regulate their surface expression of C3a and C5a receptors (C3aR/C5aR) G protein coupled receptors (GPCRs). The local C3a and C5a ligate up- regulated C3aR and C5aR on the interacting DC-CD4+ cell partners. We found that this GPCR signaling provides not only costimulatory but also survival signals that are integral to Th1 and Th17 cell responses. Importantly, our recently published work showed that the absent C3aR/C5aR signaling into naïve CD4+ cells enables auto-inductive TGF-ß signaling which represses CD4+ cell CD40L up-regulation and IL-6 production and leads to the generation of Tregs. An important clinical outcome of these findings was that in contrast difficulties in the past in generating human Tregs that exert robust suppressor activity and are stable, our findings now provide a route to achieve this. Centrally relevant to SLE, our preliminary studies now show that absent C3aR/C5aR signaling in B cells, abolishes CD40 up-regulation and IL-6 production, reduces Ab production and class switching recombination (CSR), and suppresses TLR signaling. Consistent with this, we have found that disrupting C3aR/C5aR signaling virtually abolishes disease in the pristane induced murine SLE model. MSCs, like CD4+ cells and DCs, express C3aR/C5aR. In unpublished work, we have found that disrupting C3aR/C5aR signaling into Tregs sustains Treg stability in vivo for >7 months. We additionally have developed methods to precisely quantify the effects of disrupted C3aR/C5aR signaling on MSC stability and to assess the interaction of MSCs with Tregs in vivo. The centerpiece of this proposal is that it is a collaboration between our lab and that of Arnold Caplan, a pioneer in MSC biology. The Aims are directed at optimally harnessing MSC and Treg immunosuppression for controlling SLE. The unique collaboration will be conducted with murine SLE models exploiting our novel mouse strains and with SLE patients exploiting our new insights on human Treg lineage commitment.