The Vitamin D-Gelsolin-S1P Axis in Rheumatoid Arthritis

维生素D缺乏(VitD-)在类风湿性关节炎(RA)(和其他疾病)患者中常见 自身免疫性疾病)。一些研究表明维生素D水平影响RA的表达，但其机制(S)有 在类风湿性关节炎的啮齿动物模型中没有得到很好的研究和关注。有趣的是，就像维生素D水平一样， 在只观察血浆明胶蛋白(PGSN)的研究中，观察到pGSN水平也呈负相关 C-反应蛋白(CRP)在类风湿关节炎患者中的表达。明胶蛋白(Gsn)对肿瘤坏死因子α具有保护作用 转基因(TG)类风湿关节炎小鼠模型。已知1-磷酸鞘氨醇(S1P)(通过G蛋白- T细胞、B细胞、单核/巨噬细胞和树突状细胞上的偶联受体)影响免疫和 炎症反应，已发现在RA滑液中升高，但在骨性关节炎滑液中不升高 流体。此外，pGSN与S1P结合，从而调节其与S1P受体结合的能力。我们发现 人类除了将维生素D3(VitD3)转化为25(OH)D3外，还会产生一种非钙化类似物， 20(OH)D3，血药浓度为25(OH)D3的1/20。在II型胶原诱导的关节炎中 (CIA)，我们令人惊讶地发现，20(OH)D3处理提高了pGSN水平并增加了S1P水平。 这些20(OH)D3处理的小鼠的脾细胞培养。我们发现在人类体内补充维生素D 血清中pGSN水平升高，正常人、RA和OA中的25(OH)D水平与pGSN有较好的相关性。 我们还发现，20(OH)D3和1，25(OH)2D3都能增加小鼠神经鞘氨醇激酶(Sphk)2mRNA的表达 培养的小鼠成肌细胞中脾细胞和GSN mRNA的增加以及外植体培养产生的pGSN 小鼠骨骼肌。敲除GSN或Sphk2会加重RA小鼠模型的关节炎。两个GSN 和Sphk2调节血浆或淋巴组织中的S1P水平，这在免疫功能中很重要，包括 淋巴细胞转运，Th1/Th2/Th17细胞因子的表达，以及FoxP3调节性T细胞(Tregs)的控制。不是 研究已经评估了同一RA人群中25(OH)D、S1P和pGSN的水平。我们发现了25(OH)D RA患者的血清水平与pGSN水平有很好的相关性，尽管符合率不是100%。我们 进一步假设同时具有高25(OH)D和pGSN的RA患者将有较少的RA疾病活动 低pGSN和低25(OH)D的患者RA疾病活动性评分较高。我们的 最重要的假设是VitD、GSN和CD4+T细胞Sphk2、CD4+之间存在相互作用 T细胞S1P受体亚型和/或S1P可能在调节自身免疫和 炎症性关节炎。对维生素D缺乏/不足的人服用维生素D是否会增加 PGSN水平和调节S1P，是未知的，并且是特定目标的话题3。三个高度翻译 该提案的具体目标如下：具体目标1A：评估血清水平之间的联系 25(OH)D、pGSN和S1P分别用于测量RA疾病活动性的RA患者。 具体目标1B：评估一个或多个临床预测模型是否包含血清25(OH)D， PGSN和/或S1P水平提供了对所选标记或测量的更可靠的预测 RA疾病活动比任何单一的单独预测指标都要好。具体目标2：检验维生素D的假设 用维生素D替代疗法治疗骨性关节炎或类风湿性关节炎将提高pGSN水平，降低 S1P，并改变淋巴细胞Sphk2的表达。具体目标3：检验假设 大剂量维生素D替代治疗骨性关节炎或类风湿关节炎和维生素D-将降低Th1、Th9和 Th17效应T细胞，增加外周血中Th2和CD4+Tregs，是否存在相互作用 与现有的血浆pGSN和S1P水平相一致。我们还发现，血清25(OH)D水平与 类风湿关节炎患者的pGSN和(在一项小型试点研究中)人类补充维生素D[健康志愿者 (HV)和RA患者]将25(OH)D水平从不足提高到正常范围，并与 随着pGSN的增加。这表明(在小鼠和人类中)pGSN部分受VitD的调节。

Vitamin D deficiency (VitD-) is commonly encountered in patients with rheumatoid arthritis (RA) (and other autoimmune diseases). Some studies show VitD levels impact expression of RA, but the mechanism(s) have not been well explored and have received scant attention in rodent models of RA. Interestingly, like VitD levels, in studies looking at only plasma gelsolin (pGSN), it was observed that pGSN levels also inversely correlate with C-reactive protein (CRP) in patients with RA. Gelsolin (GSN) has been shown to be protective in the TNFα transgenic (tg) mouse model of RA. It is known that sphingosine 1-phosphate (S1P) (acting through G protein- coupled receptors on T cells, B cells, monocytes/macrophages, and dendritic cells) affect immune and inflammatory responses and has been found to be elevated in RA synovial fluid but not osteoarthritis synovial fluid. Furthermore, pGSN binds to S1P, thereby regulating its ability to engage S1P receptors. We found humans, in addition to converting vitamin D3 (VitD3) to 25(OH)D3, also generate a noncalcemic analog, 20(OH)D3, with a serum concentration 1/20th of that of 25(OH)D3. In the type II collagen-induced arthritis (CIA), we found surprisingly that 20(OH)D3 treatment elevates pGSN levels and increases S1P levels in splenocyte cultures from these 20(OH)D3-treated mice. We discovered that supplementing VitD in humans elevates pGSN in sera and that 25(OH)D levels in normals and in RA and OA correlate fairly well with pGSN. Also, we found both 20(OH)D3 and 1,25(OH)2D3 increased sphingosine kinase (Sphk)2 mRNA in mouse splenocytes and increased GSN mRNA in cultured mouse myoblasts and pGSN production by explant cultures of mouse skeletal muscle. Knocking down GSN or Sphk2 worsens arthritis in mouse models of RA. Both GSN and Sphk2 regulate S1P levels in plasma or lymphoid tissue, which is important in immune function, including lymphocyte trafficking, Th1/Th2/Th17 cytokine expression, and control of FoxP3 regulatory T cells (Tregs). No studies have evaluated levels of 25(OH)D, S1P, and pGSN in the same RA population. We find 25(OH)D serum levels correlate fairly well with pGSN levels in RA patients, although concordance is not 100%. We further hypothesize that RA patients who have both high 25(OH)D and pGSN will have less RA disease activity score, while those with low pGSN and low 25(OH)D will have higher RA disease activity scores. Our overarching hypothesis is that there are interactions amongst VitD, GSN, and CD4+ T cell Sphk2, CD4+ T cell S1P receptor subtypes, and/or S1P that may be important in the modulation of autoimmunity and inflammatory arthritis. Whether administering VitD to humans with VitD deficiency/insufficiency will raise pGSN levels and modulate S1P, is unknown, and is the topic of Specific Aim 3. The three highly translational Specific Aims of this proposal are the following: Specific Aim 1A: Assess the association of serum levels of 25(OH)D, pGSN, and S1P separately, in patients with RA with measures of RA disease activity. Specific Aim 1B: Assess whether a clinical prediction model or models containing serum 25(OH)D, pGSN, and/or S1P levels provide more reliable prediction of the selected markers or measurements of RA disease activity than any single predictor alone. Specific Aim 2: To test the hypothesis that VitD replacement therapy in humans with OA or RA with VitD- will elevate levels of pGSN, reduce levels of S1P in plasma, and change lymphocyte expression of Sphk2. Specific Aim 3: To test the hypothesis that high dose VitD replacement therapy in patients with OA or RA and VitD- will reduce Th1, Th9, and Th17 effector T cells, increase Th2 and CD4+Tregs in peripheral blood, and whether there is interaction with existing plasma levels of pGSN and S1P. We also found that serum 25(OH)D levels correlate with pGSN in patients with RA and (in a small pilot study) that VitD supplementation in humans [healthy volunteers (HV) and patients with RA] raised 25(OH)D levels from insufficiency to normal range and was also associated with increases in pGSN. This suggests that (in both mice and humans) pGSN is partially regulated by VitD.