Discovery of tissue-selective, nonhypercalcemic VDR modulators for RA treatment

描述(申请人提供)：据估计，美国有130万人，尤其是女性，患有类风湿性关节炎(RA)。目前，非甾体抗炎药用于缓解症状，抗风湿病药物(DMARD)用于缓解症状。然而，这些治疗方法并不令人满意，昂贵得令人望而却步(对于基于蛋白质的DMARDS)，而且往往与潜在的严重副作用有关。过去二十年来对类风湿性关节炎免疫本质的生物学了解为使用新型小分子更好地治疗类风湿性关节炎提供了希望。我们最近发现了一类新的维生素D3(VD3)代谢物，20S-羟基维生素D3(20S(OH)D3)，即使在非常高的剂量下，也可以在体内对RA非常有效，而不会导致高钙血症或其他可检测到的毒性。在这项探索性拨款中，我们建议检验我们的总体假设，即观察到的分离对RA的强大疗效和这种独特的20-羟基支架提供的高钙血症是由于免疫细胞中VDR的选择性转录激活而不是肠道细胞。这种组织选择性，而不是 VDR激活的绝对效力，为开发临床上有用的VD3调节剂改善RA治疗提供了新的范例。我们最近开发了立体定向合成方法来制造新的类似物。其中一些类似物显示出非常有前途的抗炎活性，至少可以与20S(OH)D3相媲美。显然，在20S(OH)D3的基础上还有进一步结构优化的空间。因此，我们的目标是在这种独特的20-羟基支架的基础上开发几种具有口服活性、高度组织选择性的VDR调节剂。我们的具体目标是：(1)验证20S(OH)D3的抗炎效力可以通过合理的药物设计进一步优化的假设。我们将根据已建立的炎症标志物筛选新合成的类似物，并使用结构-活性关系(SAR)来指导对其抗炎活性的迭代优化。(2)对于TST，假设优化的高活性20(OH)D3类似物的作用机制将比肠道细胞选择性地激活免疫细胞中的VDR，并且体外观察到的选择性将转化为体内对RA的疗效。我们将测试以下假设：(A)与肠道细胞相比，它们将在免疫细胞中以不同的方式激活VDR；(B)与肠道细胞相比，它们将在免疫细胞中诱导关键的VDR反应基因的选择性表达；(C)利用已建立的胶原诱导关节炎(CIA)模型，它们将在不发生高钙血症的情况下有效地抑制RA。我们这项研究的长期目标是开发与肠道细胞相比，免疫细胞具有高度组织选择性的新型VDR调节剂。成功开发这类药物不仅将对RA产生重大影响，而且将对许多其他自身免疫性疾病的治疗产生重大影响。

DESCRIPTION (provided by applicant): An estimated 1.3 million people in the US, especially women, suffer from rheumatoid arthritis (RA). Currently NSAIDs are used to relieve symptoms, and disease-modifying antirheumatic drugs (DMARDs) are used to produce remissions. However, these treatments are not satisfactory, prohibitively expensive (for protein based DMARDs), and often associated with potentially severe side effects. Biological understanding of the underline immune nature of RA accumulated in the last two decades have provided promises in using novel small molecules for better treatment of RA. We recently discovered that a novel class of vitamin D3 (VD3) metabolites, 20S-hydroxyvitamin D3 (20S(OH)D3), is highly efficacious against RA in vivo without resulting hypercalcemia or other detectable toxicities, even at very high doses. In this exploratory grant, we propose to test our overall hypothesis that the observed separation in strong efficacy against RA and the absence of hypercalcemia provided by this unique 20-hydroxy scaffold is due to the selective transcriptional activation of VDR in immune cells compared to intestine cells. This tissue selectivity, rather than the absolute potency of VDR activation, holds a new paradigm for developing clinically useful VD3 modulators for improved RA treatment. We have recently developed stereospecific synthetic methods to make new analogs. Some of these analogs show very promising anti-inflammation activities, at least comparable to that of 20S(OH)D3. Clearly there is room for further structural optimization based on 20S(OH)D3. Therefore, our objective is to develop several orally active, highly tissue-selective, VDR modulators based on this unique 20-hydroxyscaffold. Our specific aims are: (1) To test the hypothesis that the anti-inflammatory potency of 20S(OH)D3 can be further optimized with rational drug design. We will screen newly synthesized analogs against established markers for inflammation and use the structure-activity relationships (SAR) to guide iterative optimization for their anti-inflammatory activity. (2) To tst the hypothesis that the mechanism of action of the optimized highly active 20(OH)D3 analogs will selectively activate VDR in immune cells compared to intestine cells and that the in vitro selectivity observed will translate to in vivo efficacy for RA. We will test the hypotheses that (a they will activate VDR differentially in immune cells compared to intestine cells; (b) they will induce selective expression of key VDR- responsive genes in immune cells compared to intestine cells; (c) they will suppress RA efficiently without hypercalcemia using the well-established collagen induced arthritis (CIA) model. Our long term goal for this research is to develop novel classes of highly tissue-selective VDR modulators for immune cells compared to the intestine cells. Success in developing such agents will not only have high impact for RA, but will also have significant impact in treating many other autoimmune diseases.