Complement Component C4d Deposition in the Placenta of Preeclampsia Patients and Renal Glomeruli in 1 Postpartum Renal Biopsy.

BACKGROUND

The classic disorder of placental malperfusion is preeclampsia (PE), in which the kidney is also a target organ, leading to renal dysfunction. Although the precise pathogenesis of PE is unknown, increasing evidence suggests that PE is associated with complement dysregulation. The maternal immune response to an allogenic fetus and excessive activation of the complement system may both be involved in the pathogenesis of PE. C4d deposition is considered to be evidence of antibody-mediated rejection in an allograft. This study investigated a correlation between C4d expression in the placenta and clinicopathologic features of PE patients.

MATERIALS AND METHODS

Immunohistochemical staining for C4d was performed on placental tissue of PE patients (n=70) and normal pregnancy patients (n=30). Clinicopathologic features, such as maternal age and parity, placental weight, proteinuria, and histologic features of the placenta were evaluated. One PE patient who suffered from proteinuria after delivery received a renal biopsy.

RESULTS

C4d expression was demonstrated in syncytiotrophoblast of chorionic villi. The expression of C4d was significantly more frequent in the placenta with PE (50%) than in the placenta lacking complications (14.3%) (P=0.001). C4d expression was significantly accompanied by increased syncytial knots in PE (P=0.045). Among PE patients, C4d expression was significantly correlated with low placental weight (P=0.001) and high proteinuria (P=0.018, Mann-Whitney U test). Renal biopsy of a PE patient after delivery also showed deposition of C4d along the glomerular capillary walls.

CONCLUSIONS

C4d may play an important role in placental tissue injury and in renal complications in PE.