Chondrocyte S100/Calgranulins and RAGE in Osteoarthritis

描述（由申请方提供）：低度关节内炎症促进骨关节炎（OA）的症状和疾病进展。晚期糖基化终产物多配体受体（AGEs）与几种与低度组织炎症和衰老相关的皮肤外退行性疾病有关，包括糖尿病和阿尔茨海默病。钙颗粒蛋白配体包括钙颗粒蛋白/S100蛋白，其可发挥炎性钙颗粒蛋白样作用。关节软骨细胞可表达S100 A11，OA软骨中S100 A11和S100 A11的表达上调。S100 A11诱导软骨细胞肥大。此外，CXCL 8和TNFa诱导S100 A11表达和软骨细胞肥大，并且S100 A11、CXCL 8和TNFa诱导的软骨细胞肥大是RAGE依赖性的。我们的目标是确定如何典型的软骨细胞钙颗粒蛋白S100 A11调节软骨细胞的分化和功能，在体外通过β-淀粉样蛋白信号，并确定β-淀粉样蛋白在体内OA的发病机制中的作用。我们的具体目标是：1）定义S100 A11调节软骨细胞分化和功能的分子结构要求。我们将检验S100 A11诱导软骨细胞肥大分化、MMP-13和ADAMts 5表达以及蛋白聚糖损失的假设，其方式需要一个或两个S100 A11钙结合EF手，以及通过转氨酶2（TG 2）的多聚化。2)通过S100 A11信号转导通路对软骨细胞分化和功能的影响来阐明其作用机制。我们将检验以下假设：S100 A11诱导RAGE特异性信号传导，其促进Rac 1和PI 3 K信号传导上游至MKK 3和p38 MARK活化，随后是必需的下游HDAC 4耗竭以诱导终末肥大软骨细胞分化。3)通过评估膝关节不稳定模型中的OA严重程度，对S100 A11和S100 A12直接介导小鼠OA的体内发病机制的假设进行检验。此外，我们还将测试相对于离体的S100 A11和炎性精氨酸诱导的MMP-13和ADAMts 5表达减少的S100 A11-/-小鼠股骨头软骨外植体、软骨细胞肥大和蛋白聚糖损失。这项工作的完成将通过将炎症与软骨细胞分化和功能的有害改变断开来揭示OA治疗干预的新的潜在靶点。

DESCRIPTION (provided by applicant): Low-grade intra-articular inflammation promotes symptoms and disease progression in osteoarthritis (OA). The multiligand Receptor for Advanced Glycation Endproducts (RAGE) is implicated in several extraskeletal degenerative disorders linked to low-grade tissue inflammation and aging, including diabetes mellitus and Alzheimer's Disease. RAGE ligands include calgranulin/S100 proteins that can exert inflammatory cytokine-like effects. Articular chondrocytes express RAGE, and expression of RAGE and S100A11 are up-regulated in OA cartilage. S100A11 induces chondrocyte hypertrophy. Moreover, CXCL8 and TNFa induce S100A11 expression and chondrocyte hypertrophy, and S100A11-, CXCL8-, and TNFa-induced chondrocyte hypertrophy are RAGE-dependent. Our objective is to define how the prototypical chondrocyte calgranulin S100A11 modulates chondrocyte differentiation and function in vitro via RAGE signaling, and to define the role of RAGE in pathogenesis of OA in vivo. We specifically aim to: 1) Define the molecular structural requirements by which S100A11 modulates chondrocyte differentiation and function. We will test the hypothesis that S100A11 induces hypertrophic differentiation, MMP-13 and ADAMts5 expression, and proteoglycans loss in chondrocytes in a manner that requires one or both S100A11 calcium binding EF hands, as well as multimerization by transglutaminase 2 (TG2). 2) Define the mechanism by RAGE signaling transduces S100A11 effects on chondrocyte differentiation and function. We will test the hypothesis that S100A11 induces RAGE-specific signaling that promotes Rac1 and PI3K signaling upstream to MKK3 and p38 MARK activation, followed by essential downstream HDAC4 depletion to induce terminal hypertrophic chondrocyte differentiation. 3) Test the hypothesis that S100A11 and RAGE directly mediate the pathogenesis of murine OA in vivo by assessing OA severity in a knee instability model in RAGE-/- vs. congenic RAGE+/+ mice. Also, we will test RAGE-/- mouse femoral head cartilage explants for reduced S100A11 and inflammatory cytokine-induced MMP-13 and ADAMts5 expression, chondrocyte hypertrophy, and proteoglycans loss relative to RAGE+/+ explants ex vivo. Completion of the work will reveal new potential targets for therapeutic intervention in OA by disconnecting inflammation from deleterious alteration of chondrocyte differentiation and function.