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，调节酶 脂质代谢是有趣的治疗靶点。该项目的长期目标是确定 结肠炎和结肠炎相关癌症（CAC）中的生物活性鞘脂代谢酶酸性神经酰胺酶（AC） 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的实验室在鞘脂代谢和功能方面具有既定的专业知识记录2，3。 我们最近的工作已经开始揭示骨髓（Mye）AC在结肠炎和CAC中的特定和非常独特的作用。 葡聚糖硫酸钠（DSS）诱导的小鼠结肠炎和氧化偶氮甲烷（AOM）/DSS诱导的小鼠CAC 模型中，我们发现AC表达在炎性浸润中增加，但在结肠上皮中不增加。 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。 在条件性敲除小鼠中，骨髓细胞中AC的缺失（Mye AC cKO），而不是肠上皮细胞， 减少免疫浸润并保护小鼠免于结肠炎和CAC。此外，我们发现我们的AC特异性 抑制剂LCL 521减轻慢性结肠炎模型（IL 10缺陷小鼠）中的炎症。最后，我们最新的 使用Mye AC cKO小鼠的骨髓衍生巨噬细胞（BMDM）的初步数据强烈提示， Mye AC可能是这些细胞中炎症反应所必需的。这些数据表明，Mye AC 在结肠炎和CAC的发展中起着重要作用。 基于我们大量的初步数据，我们假设Mye AC活性的丧失对以下疾病具有保护作用： 结肠炎和CAC通过调节结肠炎性浸润，靶向Mye AC可能导致新的 结肠炎和CAC的疾病改善治疗。这一假设将通过以下具体目标进行检验： 具体目标1。确定Mye AC cKO在体内保护免受慢性结肠炎和CAC。 具体目标2。确定Mye AC缺失在体内保护慢性结肠炎的机制 并在细胞中探测这些机制。 具体目标3。推进AC作为新型结肠炎和CAC靶点的药理学抑制。 这些研究的意义在于AC作为神经酰胺酶的独特作用，这在结肠炎中显然很重要 和CAC，以及AC作为新的治疗靶点的潜力。确定AC的机制 调节慢性结肠炎和CAC，特别关注Mye AC，是设计新的 针对这一途径的治疗。此外，在特定的结肠炎小鼠模型中靶向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.