ALLOANTIBODIES TO MHC INDUCES AUTOIMMUNITY AND OBLITERATIVE AIRWAY DISEASE (OAD)

 描述(申请人提供)：肺移植(LTX)是终末期肺部疾病的一种可行的治疗选择。不幸的是，移植肺的长期存活和功能受到慢性排斥反应的发展的限制，慢性排斥反应的临床诊断为闭塞性细支气管炎综合征(BOS)，这是一种不可逆转的疾病，对治疗没有反应，通常是致命的。利用新开发的闭塞性呼吸道疾病模型，我们证实了抗MHC和抗肺自身抗原的抗体(Kα1微管蛋白(Kα1T)和胶原V(Col-V))在诱导对自身抗原和肺自身抗原的细胞和体液免疫反应中起重要作用。被动应用单抗可诱导T辅助细胞(Zbtb7a)、炎症级联反应(Laptm5)和限制性调节性T细胞群(MT1)等多种重要分子的激活。我们使用同基因和同种异体小鼠单一LTX模型的结果表明，给肺AGS注射Abs可以导致OAD。此外，我们有证据表明，抗MHC的抗体以及抗Kα1T或COL-V的抗体可以打破对肺移植的耐受性，导致在MHC不匹配的LTX模型中导致OAD，在该模型中，耐受性是通过共刺激阻断建立的。应用抗Kα1T抗体后，不仅产生了对Kα1T的细胞自身免疫反应，而且对Col V和供体MHC也产生了细胞和体液反应，表明免疫反应在肺移植排斥反应中扩散。这些结果共同证明了Abs对MHC和自身AGS在OAD发病机制中的重要作用。该项目的目标是：1)利用基于RNA干扰的靶向基因敲除，确定单抗注射后导致T辅助细胞、炎症级联和T调节细胞激活的早期事件；2)确定抗MHC和抗肺自身AGS诱导外切体形成的机制，并确定外切体在免疫反应传播中的作用。我们发现，小鼠的支气管肺泡灌洗液以及抗MHC(DSA)人LTX受体的肺泡灌洗液在局部环境中含有较高浓度的外切体，表达肺自身抗原(Kα1T、Col-V和Col-I)。我们的假设是，这些外切体在激发增强的免疫反应、导致分子间扩散、打破耐受性和同种异体移植排斥反应方面发挥了重要作用。为此，我们将从BAL液中分离和鉴定外切体，并确定外切体免疫是否调节刺激自身免疫和同种免疫反应的巨噬细胞表型的极化和转换，以及3)确定中性粒细胞在抗体诱导的小鼠LTX外切体形成中的作用。该方案的总体目标是利用独特的临床前OAD小鼠模型来阐明人LTX后BOS发病中导致自身免疫的分子机制，并开发新的治疗策略来预防和/或治疗慢性肺移植排斥反应。

 DESCRIPTION (provided by applicant): Lung transplantation (LTx) is a viable treatment option for end-stage pulmonary diseases. Unfortunately long-term survival and function of lung allografts is limited by development of chronic rejection that is clinically diagnosed as bronchiolitis obliterans syndrome (BOS), an irreversible condition unresponsive to therapy and often fatal. Using newly developed models of obliterative airway disease (OAD), we demonstrated a seminal role for antibodies (Abs) to MHC and to lung self-antigens (Ags) (Kα1 Tubulin (Kα1T) and Collagen V (Col-V)) in inducing cellular and humoral immune responses to self-Ags and MHC leading to OAD. Passive administration of Abs resulted in induction of several important molecules involved in the activation of T helper cells (Zbtb7a), inflammatory cascade (Laptm5) and limiting regulatory T cell populations (Mt1). Our results using syngeneic and allogenic murine single LTx models have demonstrated that administration of Abs to lung Ags can lead to OAD. Further, we have evidence that Abs to MHC as well as Abs to Kα1T or Col-V can break tolerance to lung allografts resulting in OAD in a MHC mismatch LTx model in which tolerance was established using co-stimulatory blockade. Administration of anti-Kα1T resulted in not only cellular autoimmunity to Kα1T but also cellular as well as humoral responses to Col-V and donor MHC indicating spreading of immune responses in lung allograft rejection. These results collectively demonstrate an important role for Abs to MHC and self-Ags in the pathogenesis of OAD. The goals of this project are to: 1) define the early events following administration of Abs that leads to activation of T helper cells, inflammatory cascade, and T regulatory cells using RNA interference based targeted gene knockdown, 2) to define the mechanisms by which anti-MHC and anti-lung self-Ags induce exosome formation and define the role of exosomes in the spreading of immune responses. We demonstrated that bronchoalveolar lavage (BAL) fluids from mice following administration of Abs as well as anti-MHC (DSA)+ human LTx recipients contain increased concentration of exosomes in the local milieu, which express lung self-Ags (Kα1T, Col-V and Col-I). Our hypothesis is that these exosomes play an essential role in eliciting augmented immune responses leading to intermolecular spreading, breaking of tolerance and allograft rejection. Towards this we will isolate and characterize exosomes from BAL fluid and determine if immunization with exosomes regulates the polarization and switch in macrophage phenotypes that stimulates auto-immune and alloimmune responses, and 3) determine the role of neutrophils in the Ab induced exosome formation in murine LTx. The overall goal of this proposal is to employ unique preclinical murine models of OAD to delineate the molecular mechanisms leading to autoimmunity in the pathogenesis of BOS following human LTx and to develop new therapeutic strategies towards preventing and/or treating chronic lung allograft rejection.