Pharmacologic modulation of innate immune dysfunction in heterotopic ossification

项目总结/摘要 异位骨化是一种罕见的，但破坏性的条件不适当的骨形成。虽然免疫 系统活动是异位骨化的关键因素，我们缺乏对系统活动如何影响异位骨化的清晰理解。 免疫系统驱动骨形成。进行性骨化性纤维发育不良（FOP）是一种遗传性疾病， 大量异位骨化，与损伤后可能发生的炎性“耀斑”相关。我们 最近发现来自FOP患者的血清在基线时具有增加的促炎细胞因子水平。 此外，原代FOP单核细胞对LPS的反应性增加，LPS是一种刺激单核细胞增殖的配体。 TLR 4通路，但不与激活其他TLR受体的其他配体结合。这些初步结果导致我们 中心假设FOP是一种自身免疫性疾病，由先天免疫系统的不适当激活引起。 免疫系统尽管目前FOP尚无有效的治疗方法，但维甲酸受体-γ（RAR-γ） 激动剂可以抑制小鼠模型中的异位骨化。UCSF是正在进行的多中心II/III期 由Clementia Pharmaceuticals赞助的一项研究RAR-γ激动剂帕罗伐汀在 阻止FOP中的骨形成。一项已完成的随机化研究（NCT 02190747）的初步结果，以及 正在进行的开放标签随访研究（NCT 02279095）表明，帕罗伐汀可以减少 FOP患者异位骨形成。正在进行的开放标签PVO-1A-202（NCT 02279095）和 III PVO-1A-301（NCT 03312634）干预性试验将是拟定的独特研究的母研究 和时间敏感的机会，阐明免疫机制在FOP。在目标1中，我们将阐明 FOP原代单核细胞如何响应内源性TLR 4活化。我们将检测FOP血清中已知的 内源性TLR 4激活剂，可以在创伤后表达，并测试FOP单核细胞是否显示增加 对TLR 4激活剂如HMGB 1的反应性。在目标2中，我们将测试FOP原代单核细胞是否致敏 内皮细胞炎症。我们将使用共培养物来测定FOP单核细胞是否表现出增加的趋化性 对FOP内皮细胞，如果这是抑制palovarotene。我们还将检测FOP内皮细胞 显示在FOP单核细胞存在下促炎细胞因子表达增强。这些评估 还将显示帕洛伐汀是否影响免疫细胞功能。在目标3中，我们将确定ACVR 1和 帕罗伐汀改变先天免疫细胞活化。我们将使用单细胞RNAseq来阐明ACVR 1如何在细胞内表达。 R206 H突变改变了外周免疫细胞的组成，如果帕罗伐汀可以使这种情况正常化， 以及细胞因子产生的变化是否与炎症和FOP临床异位骨形成有关。 我们的研究结果将揭示关键的炎症机制，可能提供第一个机制， FOP中疾病活动的诊断生物标志物。这些结果也可能改善我们的治疗策略 通过鉴定可能与异位妊娠的其他病症相关的新的炎症靶点， 骨化

PROJECT SUMMARY/ABSTRACT Heterotopic ossification is a rare but devastating condition of inappropriate bone formation. Although immune system activity is a critical contributor to heterotopic ossification, we lack a clear understanding of how the immune system drives bone formation. Fibrodysplasia ossificans progressiva (FOP) is a genetic disease of massive heterotopic ossification that is associated with inflammatory “flares” that can occur after injury. We recently found that sera from FOP patients have increased levels of pro-inflammatory cytokines at baseline. Furthermore, primary FOP monocytes showed increased responsiveness to LPS, a ligand that stimulates the TLR4 pathway, but not to other ligands that activate other TLR receptors. These preliminary results lead to our central hypothesis that FOP is an autoimmune disease caused by inappropriate activation of the innate immune system. Although there are currently no effective treatments for FOP, retinoic acid receptor-γ (RAR-γ) agonists can inhibit heterotopic ossification in mouse models. UCSF is part of an ongoing multicenter Phase II/III program sponsored by Clementia Pharmaceuticals to study the efficacy of the RAR-γ agonist palovarotene in blocking bone formation in FOP. Preliminary results from a completed randomized study (NCT02190747) and ongoing open label followup study (NCT02279095) indicate that palovarotene can decrease the amount of heterotopic bone formation in FOP subjects. The ongoing open label PVO-1A-202 (NCT02279095) and Phase III PVO-1A-301 (NCT03312634) interventional trials will be the parent studies for the proposed unique and time-sensitive opportunity to elucidate the immune mechanisms in FOP. In Aim 1, we will elucidate how FOP primary monocytes respond to endogenous TLR4 activation. We will assay FOP sera for known endogenous TLR4 activators that can be expressed after trauma, and test if FOP monocytes show increased responsiveness to the TLR4 activators such as HMGB1. In Aim 2, we will test if FOP primary monocytes sensitize endothelial cells to inflammation. We will use co-cultures to assay if FOP monocytes show increased chemotaxis towards FOP endothelial cells and if this is dampened by palovarotene. We will also test if FOP endothelial cells show enhanced pro-inflammatory cytokine expression in the presence of FOP monocytes. These assessments will also show if palovarotene affects immune cell function. In Aim 3, we will determine how ACVR1 and palovarotene change innate immune cell activation. We will use single cell RNAseq to elucidate how the ACVR1 R206H mutation changes the composition of peripheral immune cells, if palovarotene can normalize this profile, and if changes in cytokine production can be linked to inflammation and FOP clinical heterotopic bone formation. Our results will reveal critical inflammatory mechanisms that may provide the first mechanistic and diagnostic biomarkers for disease activity in FOP. The results may also improve our treatment strategies by identifying novel inflammatory targets that may be relevant to other conditions of heterotopic ossification.