Department of Rheumatology C, Odense University Hospital, Odense, Denmark.
Rheumatol Int. 2011 Dec;31(12):1617-23. doi: 10.1007/s00296-010-1538-7. Epub 2010 May 29.
Surfactant protein D (SP-D) belongs to the collectin family and has pro-and anti-inflammatory capacities depending on its oligomerization. Previously, circulating SP-D was shown to be decreased in early rheumatoid arthritis (RA) and negatively correlated to disease activity. This study aimed at assessing the diurnal rhythmicity and the influence of physical activity on circulating SP-D in patients with RA at different stages compared with healthy individuals. Patients with early RA (ERA) with disease duration <6 months and with long-standing RA (LRA) with disease duration 5-15 years were included in two sub-studies. Healthy individuals served as controls. Diurnal variation: blood samples were collected every 3 h from 7 a.m to 10 p.m and the following morning. Physical activity: blood sampling was done before and after standardized physical challenge. SP-D was measured by ELISA. SP-D exhibited diurnal variation in healthy controls (n = 15) and in patients with ERA (n = 9) and LRA (n = 9) with peak values at 10 a.m. and nadir in the evening (controls: P < 0.001, ERA: P = 0.004 and LRA: P = 0.009). Three hours after cessation of physical activity, SP-D decreased below pre-exercise levels in both ERA (n = 10), LRA (n = 10) and controls (n = 13) (ERA: P < 0.001, LRA: P < 0.001 and controls: P = 0.005). In patients with RA, the decline was already observed 1 h post-exercise. Circulating SP-D exhibits diurnal variation both in patients with RA at different stages and in healthy controls. SP-D in serum decreases following physical activity in health and RA disease. This study underscores the need of standardized blood sampling conditions in future studies on SP-D.
表面活性蛋白 D（SP-D）属于凝集素家族，其具有促炎和抗炎能力，这取决于其寡聚化状态。此前的研究表明，早期类风湿关节炎（RA）患者的循环 SP-D 水平降低，且与疾病活动度呈负相关。本研究旨在评估不同阶段 RA 患者与健康个体相比，循环 SP-D 的昼夜节律性及其受体力活动的影响。本研究纳入了两个亚研究，分别为病程<6 个月的早期 RA（ERA）患者和病程 5-15 年的长期 RA（LRA）患者。健康个体作为对照。昼夜节律性：从上午 7 点到晚上 10 点每 3 小时采集一次血样，次日上午再采集一次。体力活动：在标准化体力活动挑战前后采集血样。采用 ELISA 法检测 SP-D。健康对照者（n=15）、ERA 患者（n=9）和 LRA 患者（n=9）的 SP-D 呈昼夜节律性变化，上午 10 点达峰值，傍晚达谷值（对照组：P<0.001，ERA：P=0.004，LRA：P=0.009）。在 ERA（n=10）、LRA（n=10）和对照组（n=13）患者停止体力活动后 3 小时，SP-D 下降至运动前水平以下（ERA：P<0.001，LRA：P<0.001，对照组：P=0.005）。在 RA 患者中，运动后 1 小时即可观察到 SP-D 下降。RA 不同阶段患者和健康对照者的血清 SP-D 均呈昼夜节律性变化。体力活动后健康人和 RA 患者的血清 SP-D 下降。本研究强调了未来 SP-D 研究中标准化采血条件的必要性。
