Role of T Regulatory Cell Suppression in Autoimmunity and Cancer

我们的研究表明，TNF通过作用于TNFR 2受体，这是最高的表达，在小鼠和人的TGFR 2，出乎意料的结果在增殖扩张和功能激活的TGFR 2。鉴于众所周知的促炎症作用的TNF，我们的数据显示，TNF在更延迟的方式也可以下调免疫反应，是相当令人惊讶的。此外，TNF与IL-2一起上调TNFR 2以及TcB上的4-1BB和OX-40受体的细胞表面表达。因此，TNF通过诱导3个TNFRSF受体家族成员来放大其对TNF的刺激作用。TNF与TNFR 2的相互作用也稳定了炎症部位的CD 4 + FOXP 3 + T调节细胞表型。TNF的这些意想不到的作用的一个澄清是基于我们的数据，该数据显示TNF通过活化T效应细胞也诱导它们表达更多的TNFR 2并且变得对TGF 1 α的抑制作用更具抗性。因此，活化的炎性细胞可以胜过Tcl 3的抑制作用。然而，随着炎症在愈合的伤口或非炎症肿瘤中消退，炎症占上风。约50%的肿瘤浸润性T细胞（TIL）发育成Tcells并表达TNFR 2。它们被肿瘤源性TNF激活，在外周淋巴组织中甚至比T细胞更具有免疫抑制作用。抑制TcB导致更有效的宿主抗肿瘤应答并减少肿瘤生长。我们假设TNFR 2可以被Treg的“检查点抑制剂”靶向。通过用中和抗TNFR 2抗体治疗携带小CT 26结肠肿瘤的小鼠来测试这一假设，所述中和抗TNFR 2抗体抑制TLR 9和CpG（一种TLR 9配体）以促进细胞介导的免疫。这导致80%的小鼠变得无肿瘤，并选择性地抵抗随后的CT 26肿瘤攻击。这些治疗的小鼠通过产生IFN γ而不是Treg TIL细胞发展了相当大的肿瘤浸润，并且还减少了其脾脏和肿瘤中免疫抑制性MDSC的数量。这些发现表明，这种疗法使小鼠表现出相当大的抗肿瘤免疫力。更有效的TNFR 2拮抗剂的鉴定应该产生更有效的检查点抑制。这个想法促使我们与Dimiter Dimitrov博士及其同事合作，他们设计了高亲和力抗人抗TNFR 2抗体的生产。这些抗体通过ADCC对表达TNFR 2的人细胞具有细胞毒性，但对表达TNFR 2的小鼠细胞没有细胞毒性。该抗体可能能够耗尽高度活化的人类Treg细胞和Teff细胞。虽然我们可以证明这种抗体与NK细胞一起在体外具有有效的抗TNFR 2作用，但我们不能评估其在体外或体内对小鼠细胞的作用，因为它仅对人TNFR 2有活性。因此，我们必须与一个有兴趣在患者身上进行测试的临床小组合作，以确定它是否作为一种有效的检查点样抑制剂。虽然一些公司已经表示了兴趣，但还没有一家公司获得这种抗体的许可。我们目前正在研究上调表达TNFR 2的TcR的试剂的作用效果和机制，以确定抑制自身免疫性疾病的治疗方法。

Our studies of Tregs have revealed that TNF by acting on the TNFR2 receptor, which is most highly expressed by Tregs, unexpectedly results in the proliferative expansion and functional activation of Tregs both in mice and in man. In view of the well-known proinflammatory effects of TNF, our data showing that TNF in a more delayed manner can also down-regulate immune responses, is rather surprising. Furthermore, TNF together with IL-2 up-regulates the cell surface expression of TNFR2 and also of 4-1BB and OX-40 receptors on Tregs. Thus, TNF amplifies its stimulatory effect on Tregs by inducing 3 TNFRSF receptor family members. TNF interactions with TNFR2 also stabilizes the CD4+FOXP3+ T regulatory cell phenotype at inflammatory sites. One clarification of these unexpected effects of TNF is based on our data showing that TNF by activating Teffector cells also induce them to express more TNFR2 and to become more resistant to the suppressive effects of Tregs. Thus, activated inflammatory cells can prevail over the suppressive effects of Tregs. However, as inflammation subsides in healing wounds or in non-inflamed tumors, Tregs prevail. About 50% tumor infiltrating T cells (TIL's) develop into Tregs and express TNFR2. They are activated by tumor-derived TNF to be even more immunosuppressive than Tregs in peripheral lymphoid tissues. Suppression of Tregs results in more effective host antitumor responses and reduces tumor growth. We hypothesize that TNFR2 can be targeted by "checkpoint inhibitors" of Tregs. This hypothesis was tested by treating mice bearing small CT26 colon tumors with neutralizing anti-TNFR2 antibodies, which suppresses Tregs, and CpG, a TLR9 ligand, to promote cell mediated immunity. This resulted in 80% of the mice becoming tumor free and selectively resisting a subsequent CT26 tumor challenge. These treated mice developed considerable infiltration of their tumors by IFNgamma producing rather than Treg TIL cells and also reduced the numbers of immunosuppressive MDSC in their spleens and tumors. These finding suggest that this therapy enabled the mice to exhibit considerable antitumor immunity. Identification of more potent antagonists of TNFR2 should yield even more effective checkpoint inhibition. This idea motivated us to collaborate with Dr. Dimiter Dimitrov and his colleagues who engineered the production of high affinity anti-human anti-TNFR2 antibodies. These antibodies are cytotoxic by ADCC for human, but not mouse cells expressing TNFR2. The antibody may be able to deplete both highly activated human Tregs and Teff cells. Although we can show this antibody together with NK cells has potent anti-TNFR2 effects in vitro, we can not evaluate its effects on mouse cells in vitro or in vivo because it is active only against human TNFR2. We therefore have to collaborate with a clinical group that would be interested in testing it in patients to determine if it acts as a potent checkpoint-like inhibitor. Although a number of companies have expressed an interest, none have licensed this antibody as yet. We are currently investigating the effect and mechanism of action of reagents that upregulate TNFR2 expressing Tregs to identify therapeutic approaches to inhibiting autoimmune conditions.