Microgial Iron Metabolism and Its Regulation by Cannabinoids

由于越来越多的痴呆症患者，人类衰老引起的神经退行性疾病是美国的重大健康负担。许多疾病，如阿尔茨海默氏症，都与随着年龄增长而积累的过多的脑铁有关。这样的观察导致了痴呆症的金属理论，该理论表明，随着时间的推移，环境中暴露于铁会促进神经退化。我们发现Δ、9-THC和其他大麻素类化合物通过大麻素受体-2抑制铁转运体二价金属转运体-1。CB2是一种免疫调节受体，其抗炎神经保护作用可抑制小胶质细胞的激活。小胶质细胞充当大脑和脊髓的免疫细胞，随着局部微环境的变化而激活。小胶质细胞在反应和修复状态之间两极分化，积极地从免疫刺激的抗菌表型转变为支持组织修复和炎症消退的表型。具体目的1：确定小胶质细胞铁的运输和代谢机制。我们已经确定IMG细胞的铁摄取与IMG细胞的M1/M2激活状态相对应。当非转铁蛋白(Tf)结合的铁(NTBI)被内毒素处理的细胞摄取时，Tf介导的转运被IL-4增加。根据我们的数据，我们假设小胶质细胞极化指导铁的运输。我们将：a)测试小胶质细胞极化控制铁的摄取和代谢分配到亚细胞室的假设；b)测试Aβ激活IMG细胞通过上调dmt1活性和失调能量代谢来改变小胶质细胞代谢的假设。特异性目的2：确定CB2对小胶质细胞铁转运和代谢的影响。我们已经确定了CB2选择性激动剂JWH102降低了Aβ促进的IMG细胞的促炎激活状态。我们还发现，CB2促进DMT1的去磷酸化以阻断其激活。根据我们的数据，我们假设CB2通过调节DMT1的磷酸化来重定向铁的运输和细胞的代谢。我们将：a)检验CB2选择性激动剂JWH102在脂多糖和Aβ激活的IMG细胞中减少NTBI铁转运和改变能量代谢的假说；以及b)检验CB2调节DMT1磷酸化以控制IMG细胞IS活性的假说。

Neurodegenerative diseases of human aging are significant US health burdens due to the growing number of people living with dementia. Many disorders like Alzheimer's disease are associated with excess brain iron that accumulates with age. Such observations have led to the metal theory of dementia, which suggests that over time, environmental exposure to iron promotes neurodegeneration. We have discovered that Δ9-THC and other cannabinoids inhibit the iron transporter divalent metal transporter-1 (DMT1) through cannabinoid receptor-2 (CB2). CB2 is an immunomodulatory receptor and its anti-inflammatory neuroprotective effects confer suppression of microglia activation. Microglial cells act as the immune cells of the brain and spinal cord, becoming activated by changes in their local microenvironment. Microglia polarize between reactive and repair states to actively transition from an immune-stimulating antimicrobial phenotype to one that supports tissue repair and resolution of inflammation. SPECIFIC AIM 1: Determine mechanisms of microglial iron transport and metabolism. We have determined that IMG cell iron uptake corresponds to the M1/M2 activation state of IMG cells. While more non-transferrin (Tf) bound iron (NTBI) is taken up by LPS-treated cells, Tf-mediated transport is increased by IL-4. Based on our data, we hypothesize that microglial cell polarization directs iron trafficking. We will: a) Test the hypothesis that microglial cell polarization controls uptake and metabolic partitioning of iron into subcellular compartments; and b) Test the hypothesis that IMG cell activation by Aβ alters microglia metabolism by up- regulating DMT1 activity and dysregulating energy metabolism. SPECIFIC AIM 2: Determine influence of CB2 on microglial iron transport and metabolism. We have determined the CB2 selective agonist JWH102 reduces the pro-inflammatory activation state of IMG cells promoted by Aβ. We have also found that CB2 promotes dephosphorylation of DMT1 to block its activation. Based on our data, we hypothesize that CB2 redirects iron trafficking and cellular metabolism by regulating DMT1 phosphorylation. We will: a) Test the hypothesis that the CB2 selective agonist JWH102 reduces NTBI iron transport and shifts energy metabolism in LPS and Aβ-activated IMG cells; and b) Test the hypothesis that CB2 regulates DMT1 phosphorylation to control is activity in IMG cells.