Treatment of SLE with N-acetylcysteine

描述（由申请人提供）：n -乙酰半胱氨酸（NAC）在保健食品商店有售，广泛用作抗氧化剂。NAC是l -半胱氨酸的乙酰化形式，是合成谷胱甘肽（GSH）的限速因子，谷胱甘肽是由半胱氨酸、谷氨酸和甘氨酸组成的三肽，在维持细胞内还原环境、调节线粒体跨膜电位和产生活性氧中间体（ROI）方面发挥关键作用。系统性红斑狼疮（SLE）是一种病因不明的潜在致命性自身免疫性疾病，其发病机制以t细胞异常活化和死亡为特征，这一过程关键依赖于线粒体中ROI和ATP的受控产生。我们发现狼疮T细胞表现出持续的线粒体超极化（MHP），线粒体生物发生增加，ROI产生增加，ATP和GSH消耗减少激活诱导的凋亡，反而使T细胞易于坏死，从而激活B细胞和树突状细胞并刺激SLE炎症。狼疮易感小鼠淋巴细胞中GSH也被耗尽，NAC等抗氧化剂可减少自身抗体的产生，防止肾小球肾炎的发生，延长狼疮易感小鼠的生存期。目前SLE患者的治疗基于强的松和免疫抑制剂的使用，这些药物疗效有限且副作用严重。在最近的一项欧洲研究中，在强的松和硫唑嘌呤的基础上添加NAC，可改善特发性肺纤维化患者的临床状况。NAC已被证明可以改善疲劳和肌肉耐力，这是SLE患者的主要主诉。NAC在体外和体内均能有效提高淋巴细胞胞内GSH。因此，这项双盲安慰剂对照剂量比较研究的具体目的是验证NAC治疗会导致细胞内GSH升高、逆转MHP、ATP消耗和狼疮T细胞坏死倾向的假设，从而减少B细胞和树突细胞的活化、自身抗体的产生和SLE患者的疾病活动性。在Specific Aim 1下，我们将确定NAC的每日口服剂量，该剂量耐受性良好，能够在3个月的时间内使SLE患者T细胞中GSH和MHP的消耗正常化或减缓。在Specific Aim 2下，我们将确定最佳NAC剂量对SLE患者疾病活动性和强的松使用的影响，为期12个月。作为临床结果，我们将通过SELENA/SLEDAI和BILAG评估狼疮疾病活动性、肝脏和骨髓功能、整体疲劳和肌肉耐力。作为免疫学结果，我们将评估细胞内GSH含量、MHP、ATP、Ca2+通量、坏死倾向和T细胞的线粒体基因表达特征、B细胞的激活以及单核细胞和树突状细胞NO和干扰素a的产生。本研究的结果将确定NAC是否可以恢复或至少显著调节低GSH和T细胞功能障碍、B细胞和树突状细胞的活化，从而改善SLE的疾病表现。

DESCRIPTION (provided by applicant): N-acetylcysteine (NAC) is available in health food stores and widely used as an antioxidant. NAC is the acetylated form of L-cysteine, a rate-limiting factor in synthesis of glutathione (GSH), tripeptide made up of cysteine, glutamic acid, and glycine, which plays key roles in maintenance of a reducing intracellular environment, regulation of the mitochondrial transmembrane potential, and production of reactive oxygen intermediates (ROI). The pathogenesis of systemic lupus erythematosus (SLE), a potentially fatal autoimmune disease of unknown etiology, is characterized by abnormal T-cell activation and death, processes which are crucially dependent on the controlled production of ROI and of ATP in the mitochondria. We found that lupus T cells exhibit persistent mitochondrial hyperpolarization (MHP), increased mitochondrial biogenesis, and increased ROI production as well as depletion of ATP and GSH which decrease activation-induced apoptosis and instead predispose T cells for necrosis, thus activating B cells and dendritic cells and stimulating inflammation in SLE. GSH is also depleted in lymphocytes of lupus-prone mice and NAC and other antioxidants reduce autoantibody production, prevent the development of glomerulonephritis, and prolong the survival of lupus-prone mice. Current therapy of SLE patients is based on the use of prednisone and immunosuppressants which have limited efficacy and serious side-effects. In a recent European study, NAC, added to prednisone and azathioprine, resulted in clinical improvement of patients with idiopathic pulmonary fibrosis. NAC has been shown to improve fatigue and muscle endurance, a major complaint in patients with SLE. NAC can effectively raise intracellular GSH of lymphocytes both in vitro and in vivo. Therefore, the specific aims of this double-blind placebo-controlled dose-comparison study will test the hypothesis that treatment with NAC will result in elevation of intracellular GSH and reverse the MHP, ATP depletion and predisposition of lupus T cells to necrosis and, consequently, diminish activation of B cells and dendritic cells, production of auto-antibodies, and disease activity in patients with SLE. Under Specific Aim 1, we will determine the daily oral dose of NAC that is well tolerated and capable of normalizing or moderating the depletion of GSH and MHP in T cells of patients with SLE over a period of 3 months. Under Specific Aim 2, we will determine the impact of an optimal NAC dose on disease activity and prednisone use in patients with SLE over a period of 12 months. As clinical outcomes, we will assess lupus disease activity by SELENA/SLEDAI and BILAG, liver and bone marrow function, overall fatigue, and muscle endurance. As immunological outcomes, we will assess intracellular GSH content, MHP, ATP, Ca2+ fluxing, predisposition to necrosis and mitochondrial gene expression signature of T cells, activation of B cells, and production of NO and interferon-a by monocytes and dendritic cells. The results of this study will establish whether administration of NAC can restore or at least significantly modulate low GSH and dysfunction of T cells, activation of B cells and dendritic cells, and thus improve the disease manifestations in SLE. PUBLIC HEALTH REVELANCE: Systemic lupus erythematosus (SLE) is a chronic inflammatory disease which often has debilitating and potentially life-threatening consequences. The cause of SLE is unknown and current therapies lack specificity and carry significant side effects. Existing data in the literature provide evidence that a natural antioxidant, glutathione, is depleted in T cells of patients with SLE which may be a key factor underlying abnormal activation and predisposition of T lymphocytes to pro-inflammatory cell death via necrosis. Administration of N-acetylcysteine (NAC), that serves as a precursor of GSH, improves the clinical outcome of murine lupus, and limits the toxicity of pro-oxidant/immunosuppressant medications (4) commonly used in patients with SLE. NAC is widely available in health food stores and large doses (up to 8 g/day) can be safely administered to humans(1). In a one-year study of patients with inflammatory lung disease treated with prednisone and azathioprine, addition of NAC (1.8g/day) diminished disease severity and reduced drug toxicity in comparison to placebo. Moreover, oral NAC has been found to improve muscle fatigue (5-7) which is reported to be the most disabling symptom in 53% of patients with SLE (8). Thus, establishing a dose ranging between 1.8-7.2 g/day that is well-tolerated and capable of raising intracellular GSH in lupus patients and determining its immunological and therapeutic impact in SLE appear to be well justified.