Hyaluronan (HA) and Serum-derived Hyaluronan Associated Protein (SHAP)-HA Complex as Markers of Pre-eclampsia

OBJECTIVES: Extracellular matrix containing hyaluronan (HA) and serum-derived hyaluronan associated protein (SHAP) plays important roles in regulating cellular behavior in a variety of physiological and pathological processes. SHAP, the heavy chains of serum inter-α-trypsin inhibitor family molecules, are able to form a covalent complex with hyaluronan. To investigate the role of HA, serum-derived hyaluronan associated protein (SHAP)-HA complex and HA synthase (HAS) in pregnancy complicated by pre-eclampsia, serum concentrations of HA and SHAP-HA complex, concentrations of urinary bikunin (UTI), placental concentrations of HA, and histochemical localization of HA, HAS, CD44, inter-α-trypsin inhibitor (ITI) and bikunin in placenta were examined using sera, urine and placental tissues obtained from pregnant women with or without pre-eclampsia. MATERIALS AND METHODS: Placenta tissue samples, urine and sera were obtained from 20 patients with pre-eclampsia and 60 women with uncomplicated pregnancy. Concentrations of HA and UTI were measured using inhibitory sandwich enzyme-linked immunosorbent assay (ELISA). Concentrations of SHAP-HA complex were measured using sandwich ELISA. Agarose gel electrophoresis was used to analyze distributions of HA molecular weight. Immunohistochemistry for HAS, CD44, ITI and bikunin in placental tissue was performed using avidin-biotin-peroxidase complex methods. Localization of HA in tissues was performed using biotinylated HA binding protein. RESULTS: Serum concentrations of HA, SHAP-HA complex and UTI were higher in the pre-eclampsia group than in the uncomplicated pregnancy group. In addition, serum concentrations of SHAP-HA complex were higher in severe pre-eclampsia than in mild pre-eclampsia, although concentrations of HA and UTI did not differ between pre-eclampsia subgroups. Concentrations of HA in placental tissue were higher in the pre-eclampsia group than in the uncomplicated pregnancy group, and also higher in mild pre-eclampsia than in severe pre-eclampsia. The molecular weight of HA in placental tissue displayed a distribution of 500-1300 kDa, and distribution patterns did not differ between uncomplicated pregnancy and pre-eclampsia. Expression of HAS1 was found frequently in pre-eclampsia compared with uncomplicated pregnancy, but no differences were noted in the expressions of HAS2, HAS3, CD44, ITI and bikunin in placental tissues. On histochemical examination, all villi displayed homogenous patterns of HA expression in stromal tissue and arterial walls. In cases of pre-eclampsia, intense HA staining was also observed in the stroma of stem villi, adjacent to fibrinoid deposits. Concentrations of HA in placental tissue and serum were higher in HAS1-positive placentas than in HAS1-negative placentas. This difference was observed specifically in pre-eclampsia. Receiver operating characteristic curve for serum SHAP-HA complex displayed excellent diagnostic accuracy in discriminating between severe and mild pre-eclampsia. CONCLUSION: The SHAP-HA complex offers a new predictive marker for monitoring severity of pre-eclampsia.