Regulation of the intestinal stem cell compartment after hematopoietic transplantation

 描述（由申请人提供）：胃肠道（GI）损伤是造血干细胞/骨髓移植（BMT）的常见并发症。这种治疗相关的毒性可能是由于移植前调节或T细胞介导的移植物抗宿主病（GVHD），目前对GI GVHD的免疫抑制治疗是不够的。肠干细胞（ISC）损伤对GVHD病理生理学的贡献以及免疫系统在介导ISC区室损伤中的作用知之甚少。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，为研究损伤与GVHD之间的关系提供了机会。 在所产生的肠道病理学中，ISC与ISC小生境的损伤。该项目汇集了一个多学科团队，他们在粘膜免疫学，GVHD和辐射损伤的GI损伤，ISC生物学和细胞因子信号传导方面具有专业知识，以全面了解BMT和GVHD如何影响ISC区室并导致肠道损伤。我们的初步数据表明，在实验性GVHD中，构成干细胞龛的ISCs和潘氏细胞都被耗尽。此外，发现ISC表达白细胞介素-22（IL-22）的受体。最近已经显示肠内IL-22的信号传导限制受伤上皮中的病理学。我们发现，在体内给予IL-22的小鼠骨髓移植后减少GVHD相关的肠道病理和限制损失的ISCs由于GVHD。我们还发现，用IL-22离体肠隐窝培养导致肠类器官的生长和ISC再生增加。最后，类器官生长也被F-652（一种重组人IL-22二聚体）增强，并且用F-652治疗移植小鼠导致GVHD的全身体征减少和GVHD死亡率显著降低。我们建议测试这一假设，即骨髓移植后的ISCs的损失是由于条件相关的和免疫介导的损害的ISC室，我们假设，上皮再生中的IL-22的好处是由于直接刺激的ISCs。ISC功能和ISC消耗将在实验BMT模型中进行B评价，利用GVHD的体内模型和肠类器官的离体培养。此外，我们将测试IL-22保护ISC区室免受损伤的机制。因此，BMT后用IL-22治疗将被评估为上皮聚焦的再生免疫疗法，以通过促进ISC功能来降低移植相关的发病率和死亡率。目前还不存在加速组织从GVHD中恢复的疗法，但这种策略，可能与F-652一起，可以与免疫抑制方法一起以互补的方式工作，以治疗GVHD并减少组织损伤。该项目将导致更好地了解ISC隔室和免疫系统之间的相互作用，为通过增强组织再生治疗炎症性GI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.