Regulation of the intestinal stem cell compartment after hematopoietic transplantation

 描述(申请人提供)：胃肠道(Gl)损伤是造血干细胞/骨髓移植(BMT)的常见并发症。这种与治疗相关的毒性可能是由于移植前的条件反射或T细胞介导的移植物抗宿主病(GVHD)，而目前GI GVHD的免疫抑制治疗是不够的。肠干细胞(ISC)损伤在GVHD病理生理学中的作用以及免疫系统在介导ISC损伤中的作用还知之甚少。急性GI GVHD的实验模型紧密地概括了临床疾病的免疫病理生理学，提供了一个机会来研究损伤与 在由此导致的肠道病理中，ISCS与ISC壁龛的损伤。这个项目汇集了一个多学科的团队，他们拥有黏膜免疫学、GVHD和辐射损伤引起的GI损伤、ISC生物学和细胞因子信号转导方面的专业知识，以全面了解BMT和GVHD如何影响ISC间隔室并导致肠道损伤。我们的初步数据表明，在实验性GVHD中，ISCs和构成干细胞生态位的Paneth细胞都被耗尽。此外，还发现ISCs表达白介素22受体(IL-22)。最近研究表明，肠道内的IL-22信号可以限制损伤上皮的病理改变。我们发现，骨髓移植后给小鼠体内应用IL-22可以减少GVHD相关的肠道病理，并限制GVHD引起的ISCs的丢失。我们还发现，体外肠道隐窝培养加IL-22可以促进肠道器官的生长和ISC的再生。最后，重组人IL-22二聚体F-652也促进了器官的生长，用F-652治疗移植小鼠后，GVHD的全身症状减少，GVHD死亡率显著降低。我们提出的假设是，骨髓移植后ISCs的丢失是由于条件相关和免疫介导的ISC室损伤，我们假设IL-22在上皮再生中的好处是由于ISCs的直接刺激。在实验性的骨髓移植模型中，将利用GVHD的体内模型和体外培养的肠道器官来评估ISC的功能和ISC的耗竭。此外，我们还将测试IL-22保护ISC隔室免受损伤的机制。因此，骨髓移植后使用IL-22治疗将被评估为一种以上皮为重点的再生免疫疗法，通过促进ISC功能来降低移植相关的发病率和死亡率。目前还不存在加速GVHD组织恢复的治疗方法，但这种策略可能与F-652一起使用，与免疫抑制方法相辅相成，治疗GVHD并减少组织损伤。该项目将有助于更好地了解ISC间隔和免疫系统之间的相互作用，为通过增强组织再生来治疗炎症性胃肠道疾病开辟新的方向。

 DESCRIPTION (provided by applicant): Damage to the gastrointestinal (Gl) tract is a frequent complication of hematopoietic stem cell/bone marrow transplantation (BMT). This therapy-related toxicity may be due to pre-transplant conditioning or T cell-mediated graft vs. host disease (GVHD), and current immunosuppressive treatments for GI GVHD are inadequate. The contribution of intestinal stem cell (ISC) damage to GVHD pathophysiology and the role of the immune system in mediating damage to the ISC compartment are poorly understood. Experimental models of acute GI GVHD closely recapitulate the immunologic pathophysiology of the clinical disease, providing an opportunity to investigate the relationship between injury to ISCs vs. injury to the ISC niche in the resulting intestinal pathology. This project brings togethe a multi-disciplinary team with expertise in mucosal immunology, GI damage from GVHD and radiation injury, ISC biology, and cytokine signaling to develop a comprehensive understanding of how BMT and GVHD can influence the ISC compartment and lead to intestinal damage. Our preliminary data demonstrate that both ISCs and the Paneth cells constituting the stem cell niche are depleted in experimental GVHD. Additionally, ISCs were found to express the receptor for Interleukin-22 (IL-22). Signaling of IL-22 within the intestines has recently been shown to limit pathology in wounded epithelium. We found that in vivo administration of IL-22 to mice post-BMT reduced GVHD-related intestinal pathology and limited the loss of ISCs due to GVHD. We also found that ex vivo intestinal crypt culture with IL-22 led to increased growth of intestinal organoids and ISC regeneration. Finally, organoid growth was also enhanced by F-652, a recombinant human IL-22 dimer, and treatment of transplanted mice with F-652 led to reduced systemic signs of GVHD and significantly reduced GVHD mortality. We propose to test the hypothesis that the loss of ISCs after BMT is due to both conditioning-related and immune-mediated damage to the ISC compartment, and we hypothesize that the benefit of IL-22 in epithelial regeneration is due to direct stimulation of ISCs. ISC function and ISC depletion will b evaluated in experimental BMT models, utilizing both in vivo models of GVHD and ex vivo culture of intestinal organoids. In addition, we will test the mechanisms by which IL-22 can protect the ISC compartment from injury. Treatment with IL-22 post-BMT will thus be evaluated as an epithelial-focused regenerative immunotherapy to reduce transplant-related morbidity and mortality by promoting ISC function. No current therapy exists to accelerate tissue recovery from GVHD, but such a strategy, potentially with F-652, could work in a complimentary fashion with immunosuppressive approaches to treat GVHD and reduce tissue damage. This project will lead to a better understanding of the interactions between the ISC compartment and the immune system, opening a new direction for treatment of inflammatory GI disease by augmenting tissue regeneration.