Department of Pediatrics, Zadar General Hospital, Zadar, Croatia.
Division of Nephrology, Dialysis and Transplantation, Department of Pediatrics, University Hospital Centre Zagreb, Zagreb, Croatia.
Front Immunol. 2021 Feb 19;11:631299. doi: 10.3389/fimmu.2020.631299. eCollection 2020.
Serum amyloid A (SAA) is an acute phase protein with a significant importance for patients with inflammatory rheumatic diseases (IRD). The central role of SAA in pathogenesis of IRD has been confirmed by recent discoveries, including its involvement in the activation of the inflammasome cascade and recruitment of interleukin 17 producing T helper cells. Clinical utility of SAA in IRD was originally evaluated nearly half a century ago. From the first findings, it was clear that SAA could be used for evaluating disease severity and monitoring disease activity in patients with rheumatoid arthritis and secondary amyloidosis. However, cost-effective and more easily applicable markers, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), overwhelmed its use in clinical practice. In the light of emerging evidences, SAA has been discerned as a more sensitive biomarker in a wide spectrum of IRD, especially in case of subclinical inflammation. Furthermore, a growing number of studies are confirming the advantages of SAA over many other biomarkers in predicting and monitoring response to biological immunotherapy in IRD patients. Arising scientific discoveries regarding the role of SAA, as well as delineating SAA and its isoforms as the most sensitive biomarkers in various IRD by recently developing proteomic techniques are encouraging the revival of its clinical use. Finally, the most recent findings have shown that SAA is a biomarker of severe Coronavirus disease 2019 (COVID-19). The aim of this review is to discuss the SAA-involving immune system network with emphasis on mechanisms relevant for IRD, as well as usefulness of SAA as a biomarker in various IRD. Therefore, over a hundred original papers were collected through an extensive PubMed and Scopus databases search. These recently arising insights will hopefully lead to a better management of IRD patients and might even inspire the development of new therapeutic strategies with SAA as a target.
血清淀粉样蛋白 A（SAA）是一种急性时相蛋白，对炎症性风湿病（IRD）患者具有重要意义。SAA 在 IRD 发病机制中的核心作用已被最近的发现所证实，包括其参与炎症小体级联的激活和白细胞介素 17 产生的辅助性 T 细胞的募集。SAA 在 IRD 中的临床应用价值最初是在近半个世纪前评估的。从最初的发现中可以清楚地看出，SAA 可用于评估类风湿关节炎和继发性淀粉样变性患者的疾病严重程度和监测疾病活动。然而，成本效益更高且更容易应用的标志物，如 C 反应蛋白（CRP）和红细胞沉降率（ESR），在临床实践中超过了 SAA 的应用。鉴于新出现的证据，SAA 已被视为广泛的 IRD 中更敏感的生物标志物，尤其是在亚临床炎症的情况下。此外，越来越多的研究证实，SAA 在预测和监测 IRD 患者对生物免疫治疗的反应方面优于许多其他生物标志物。关于 SAA 作用的新发现，以及最近开发的蛋白质组学技术将 SAA 及其同工型确定为各种 IRD 中最敏感的生物标志物，正在鼓励其临床应用的复兴。最后，最近的研究结果表明，SAA 是严重 2019 年冠状病毒病（COVID-19）的生物标志物。本综述的目的是讨论 SAA 参与的免疫系统网络，重点是与 IRD 相关的机制，以及 SAA 作为各种 IRD 生物标志物的用途。因此，通过广泛的 PubMed 和 Scopus 数据库搜索收集了一百多篇原始论文。这些新出现的见解有望改善 IRD 患者的管理，甚至可能激发以 SAA 为靶点的新治疗策略的发展。
