The aetiologies and pathogeneses of the joint diseases rheumatoid arthritis (RA) and spondyloarthritis (SpA) are still not fully elucidated. To increase our understanding of the molecular pathogenesis, we analysed the protein composition of synovial fluid (SF) from rheumatoid arthritis (RA) and spondyloarthritis (SpA) patients. Fifty-six synovial fluid samples (RA, n = 32; SpA, n = 24) were digested with trypsin, and the resulting peptides were separated by liquid chromatography and analysed by tandem mass spectrometry. Additionally, the concentration of cell-free DNA (cfDNA) in the synovial fluid was measured, and plasma C-reactive protein (CRP) was determined. Three hundred thirty five proteins were identified within the SF. The more abundant proteins seen in RA SF were inflammatory proteins, including proteins originating from neutrophil granulocytes, while SpA SF had less inflammatory proteins and a higher concentration of haptoglobin. The concentration of cell-free DNA in the SF increased together with proteins that may have originated from neutrophils. Plasma CRP levels in both RA and SpA, correlated to other acute phase reactants. The proteomic results underline that neutrophils are central in the RA pathology but not in SpA, and even though inhibitors of neutrophils (migration, proteinase inhibitors) were present in the SF it was not sufficient to interrupt the disease process.

中文翻译：

---

风湿性关节炎和脊柱关节炎患者滑液的蛋白质组学分析。

关节疾病类风湿性关节炎（RA）和脊柱关节炎（SpA）的病因和发病机制仍未完全阐明。为了增加我们对分子发病机制的理解，我们分析了类风湿关节炎 (RA) 和脊柱关节炎 (SpA) 患者的滑液 (SF) 的蛋白质组成。56 个滑液样品（RA，n = 32；SpA，n = 24）用胰蛋白酶消化，所得肽通过液相色谱分离并通过串联质谱分析。此外，还测量了滑液中游离 DNA (cfDNA) 的浓度，并测定了血浆 C 反应蛋白 (CRP)。在 SF 中鉴定出 335 种蛋白质。在 RA SF 中看到的更丰富的蛋白质是炎症蛋白，包括源自中性粒细胞的蛋白质，而 SpA SF 的炎症蛋白较少，触珠蛋白浓度较高。SF 中无细胞 DNA 的浓度与可能源自中性粒细胞的蛋白质一起增加。RA 和 SpA 中的血浆 CRP 水平与其他急性期反应物相关。蛋白质组学结果强调中性粒细胞在 RA 病理学中是中心，但在 SpA 中不重要，即使 SF 中存在中性粒细胞抑制剂（迁移、蛋白酶抑制剂），也不足以中断疾病过程。与其他急性期反应物相关。蛋白质组学结果强调中性粒细胞在 RA 病理学中是中心，但在 SpA 中不重要，即使 SF 中存在中性粒细胞抑制剂（迁移、蛋白酶抑制剂），也不足以中断疾病过程。与其他急性期反应物相关。蛋白质组学结果强调中性粒细胞在 RA 病理学中是中心，但在 SpA 中不重要，即使 SF 中存在中性粒细胞抑制剂（迁移、蛋白酶抑制剂），也不足以中断疾病过程。