TY - JOUR
T1 - Long-term stability and circadian variation in circulating levels of surfactant protein D
AU - Hoegh, Silje Vermedal
AU - Sorensen, Grith Lykke
AU - Tornoe, Ida
AU - Lottenburger, Tine
AU - Ytting, Henriette
AU - Nielsen, Hans Jørgen
AU - Junker, Peter
AU - Holmskov, Uffe
AU - Hoegh, Silje Vermedal
AU - Sorensen, Grith Lykke
AU - Tornoe, Ida
AU - Lottenburger, Tine
AU - Ytting, Henriette
AU - Nielsen, Hans Jørgen
AU - Junker, Peter
AU - Holmskov, Uffe
N1 - Keywords: Adult; Aged; Circadian Rhythm; Exercise; Female; Humans; Male; Middle Aged; Protein Stability; Pulmonary Surfactant-Associated Protein D
PY - 2010/4
Y1 - 2010/4
N2 - Surfactant protein D (SP-D) is an oligomeric calcium-dependent lectin with important roles in innate host defence against infectious microorganisms. Several studies have shown that patients with inflammatory lung disease have elevated levels of circulating SP-D, and serum SP-D has been suggested to be used as a biomarker for disease e.g. in COPD. We aimed to investigate the variation of circulating SP-D in healthy individuals in and between days for 6 months. In addition, we studied the SP-D response to a standardized physical exercise programme. SP-D was measured in serum using a 5-layered ELISA technique. We found that circulating SP-D remained constant over a 6-month period. However, during the course of one day SP-D varied significantly. Median SP-D peaked at 10 a.m. at 1009 ng/ml (95% CI: 803-1497), subsequently decreasing to nadir at 10 p.m. at 867 ng/ml (95% CI: 650-1148)(P<0.00005). Median pre-exercise level of SP-D was 746 ng/ml (95% CI: 384-2035), and immediately after cessation of physical activity the median SP-D level was 767 ng/ml (95% CI: 367-1885) (P=0.248). Our findings underscore the importance of standardized blood sampling conditions in future studies on the potential role of SP-D as a biomarker. Importantly, stable measures of systemic SP-D over a prolonged period support that SP-D is suitable for biomarker studies.
AB - Surfactant protein D (SP-D) is an oligomeric calcium-dependent lectin with important roles in innate host defence against infectious microorganisms. Several studies have shown that patients with inflammatory lung disease have elevated levels of circulating SP-D, and serum SP-D has been suggested to be used as a biomarker for disease e.g. in COPD. We aimed to investigate the variation of circulating SP-D in healthy individuals in and between days for 6 months. In addition, we studied the SP-D response to a standardized physical exercise programme. SP-D was measured in serum using a 5-layered ELISA technique. We found that circulating SP-D remained constant over a 6-month period. However, during the course of one day SP-D varied significantly. Median SP-D peaked at 10 a.m. at 1009 ng/ml (95% CI: 803-1497), subsequently decreasing to nadir at 10 p.m. at 867 ng/ml (95% CI: 650-1148)(P<0.00005). Median pre-exercise level of SP-D was 746 ng/ml (95% CI: 384-2035), and immediately after cessation of physical activity the median SP-D level was 767 ng/ml (95% CI: 367-1885) (P=0.248). Our findings underscore the importance of standardized blood sampling conditions in future studies on the potential role of SP-D as a biomarker. Importantly, stable measures of systemic SP-D over a prolonged period support that SP-D is suitable for biomarker studies.
U2 - 10.1016/j.imbio.2009.05.001
DO - 10.1016/j.imbio.2009.05.001
M3 - Journal article
C2 - 19540617
SN - 0171-2985
VL - 215
SP - 314
EP - 320
JO - Immunobiology
JF - Immunobiology
IS - 4
ER -