Role for myeloid acid ceramidase in colon inflammation and cancer

生物活性脂质，如神经酰胺及其下游代谢物、鞘氨醇和鞘氨醇-1-磷酸 (S1P)，介导关键的生物反应，包括炎症和癌症1。因此，调节的酶 脂代谢是耐人寻味的治疗靶点。该项目的长期目标是定义 生物活性鞘脂代谢酶--酸性神经酰胺酶(AC)在结肠炎和结肠炎相关癌中的作用 并确定靶向这种酶是否可以作为一种新的抗炎/抗CAC疗法。 PI的实验室在鞘磷脂新陈代谢和功能2方面拥有成熟的专业记录。 我们最近的工作已经开始揭示髓系(Mye)AC在结肠炎和CAC中的特定和非常独特的作用。 用葡聚糖硫酸钠(DSS)诱导小鼠结肠炎和偶氮甲烷(AOM)/DSS诱导小鼠CAC 模型中，我们发现AC在炎性浸润物中表达增加，但在结肠上皮中不表达。 同样，我们观察到结肠炎和结肠癌患者组织巨噬细胞中AC表达增加。 在条件性基因敲除小鼠中，髓系细胞(Mye AC CKO)中的AC缺失，但不是肠上皮细胞， 减少免疫渗透，保护小鼠免受结肠炎和CAC的侵袭。此外，我们发现我们的特定于AC的 抑制剂LCL521可以减轻慢性结肠炎模型(IL10缺陷小鼠)的炎症。最后，我们最新的 使用来自Mye AC CKO小鼠的骨髓来源的巨噬细胞(BMDM)的初步数据强烈提示 这些细胞的炎症反应可能需要MYE AC。这些数据加在一起表明，Mye AC 在结肠炎和CAC的发展中起着很大的作用。 根据我们大量的初步数据，我们假设Mye AC活性的丧失对 通过调节结肠炎和CAC以及靶向Mye AC可能导致新的 疾病修正疗法在结肠炎和CAC中的应用。这一假设将通过以下具体目标进行检验： 具体目的1.建立Mye AC CKO对慢性结肠炎和CAC的体内保护作用。 特定目的2.在体内确定Mye AC缺失对慢性结肠炎的保护机制 并在细胞中探索这些机制。 具体目的3.AC作为一种新的结肠炎和CAC靶点的药物抑制研究进展。 这些研究的意义在于AC作为神经酰胺酶的独特作用，这在结肠炎中显然是重要的 和CAC，以及AC作为新的治疗靶点的潜力。确定AC通过哪些机制 调节慢性结肠炎和CAC，特别关注Mye AC，是设计新药的关键第一步 针对这一途径的治疗。此外，针对特定结肠炎和结肠炎小鼠模型的AC的研究 CAC将使我们能够在不久的将来开始将我们的研究转化为临床治疗方法。

Bioactive lipids, such as ceramide and its downstream metabolites, sphingosine, and sphingosine-1-phosphate (S1P), mediate critical biologic responses, including inflammation and cancer1. Thus, the enzymes regulating lipid metabolism are intriguing therapeutic targets. The long-term goal of this project is to define the role of the bioactive sphingolipid metabolizing enzyme, acid ceramidase (AC), in colitis and colitis-associated cancer (CAC) and determine whether targeting this enzyme could serve as a novel anti-inflammatory/anti-CAC therapy. The PI’s laboratory has an established track record of expertise in sphingolipid metabolism and function2,3. Our recent work has begun to uncover a specific and very unique role for myeloid (Mye) AC in colitis and CAC. Using dextran sodium sulfate (DSS)-induced colitis and azoxymethane (AOM)/DSS-induced CAC in murine models, we found that AC expression is increased in the inflammatory infiltrate but not in the colon epithelium. Similarly, we observed increased AC expresion in tissue macrophages in humans with colitis and colon cancer. In conditional knockout mice deletion of AC in myeloid cells, (Mye AC cKO), but not intestinal epithelial cells, decreased immune infiltrate and protected mice from colitis and CAC. Moreover, we found that our AC-specific inhibitor, LCL521, attenuates inflammation in a chronic colitis model (IL10 deficient mice). Finally, our newest preliminary data using bone marrow derived macrophages (BMDMs) from Mye AC cKO mice strongly hint that Mye AC may be required for inflammatory responses in these cells. Together these data suggest that Mye AC plays a large role the development of colitis and CAC. Based on our substantial preliminary data, we hypothesize that loss of Mye AC activity is protective against colitis and CAC by modulating colonic inflammatory infiltrate, and that targeting Mye AC may result in novel disease-modifying therapy in colitis and CAC. This hypothesis will be tested by the following Specific Aims: Specific Aim 1. Establish that Mye AC cKO protects from chronic colitis and CAC in vivo. Specific Aim 2. Determine the mechanisms by which loss of Mye AC protects from chronic colitis in vivo and probe these mechanisms in cells. Specific Aim 3. Advance pharmacologic inhibition of AC as a novel colitis and CAC target. The significance of these studies lies in the unique role of AC as the ceramidase that is clearly important in colitis and CAC, and the potential for AC as a novel therapeutic target. Identifying the mechanisms by which AC regulates chronic colitis and CAC, with specific focus on Mye AC, is a crucial first step in the design of novel therapies targeting this pathway. In addition, the studies that target AC in specific mouse models of colitis and CAC, will allow us to begin to translate our studies into clinical therapeutic approaches in the very near future.