Table 1.
Changes in the complement system during PE and related pregnancy disorders.
| Complement element | Details | Reference |
|---|---|---|
| Bb | Raised in PE, OR 2.1 (CI 1.4–3.1, P < 0.0003). | (205) |
| Bb | Adjustment for risk factors did not attenuate the association between an elevated Bb and preeclampsia [adjusted odds ratio (aOR) 3.8, 95% CI 1.6–9, P < 0.002] in the cohort. After removing women with plasma obtained before 10 weeks, the adjusted OR of Bb in the top decile for preeclampsia was 6.1 (95% CI 2.2–17, P < 0.0005) | (204) |
| Bb | Median Bb levels were higher in the maternal plasma of severe PE subjects (n = 24) than in controls (n = 20), 1.45 ± 1.03 versus 0.65 ± 0.23 µg/mL, P < 0.001 | (214) |
| Bb | Preterm birth. Women with Bb in the top quartile were 4.7 times more likely to have an SPTB less than 34 weeks’ gestation as compared with women who had levels of Bb in the lower 3 quartiles (CI 1.5–14, P < 0.003) | (203) |
| Bb | Maternal Bb levels were significantly higher in the preeclamptic group than in the nonpreeclamptic group (P < 0.003 in all studied, P < 0.007 in African Americans) | (218) |
| Bb | Pyelonephritis. Pregnant women with pyelonephritis had a higher median plasma concentration of fragment Bb than those with a normal pregnancy (1.3 mg/ml, IQR: 1.1–1.9 vs. 0.8 mg/ml, IQR: 0.7–0.9; P < 0.001). No significant differences were observed in the median maternal plasma concentration of fragment Bb between pregnant women with pyelonephritis who had a positive blood culture and those with a negative blood culture | (219) |
| Bb | Median amniotic fluid Bb levels were also significantly higher (P = 0.03) in preeclamptic women than in normal pregnant women (1,127 versus 749 ng/mL). The alternative complement pathway is principally involved | (215) |
| Bb, C3a, C5a, and MAC | Increased significantly in EOSPE (all P < 0.01) and LOSPE (P-value: 0.027, <0.001, 0.001, and <0.001, respectively) compared with Early/Late control | (216). See also (220) |
| Bb or C3a | Women who were obese with levels of Bb or C3a in the top quartile were 10.0 (95% confidence interval, 3.3–30) and 8.8 (95% confidence interval, 3–24) times, respectively, more likely to develop preeclampsia compared with the referent group at 20 weeks gestation | (221) |
| C1q and C4d | Increased significantly in LOSPE (P-value: 0.003 and.014, respectively) compared with L-control | (216). See also (220) |
| C3a | Adjusted for parity and prepregnancy body mass index, women with levels of C3a in the upper quartile in early pregnancy were three times more likely to have an adverse outcome later in pregnancy compared with women in the lowest quartile (95% confidence interval, 1.8–4.8; P < 0.001). This was especially the case for preterm birth (P < 0004). Elevated C3a as early as the first trimester of pregnancy is an independent predictive factor for adverse pregnancy outcomes, suggesting that complement-related inflammatory events in pregnancy contribute to the subsequent development of poor outcomes at later stages of pregnancy | (208) |
| C3a | Autoantibody-mediated complement C3a receptor activation contributes to the pathogenesis of preeclampsia. | (211) |
| C3a | Women who developed early-onset preeclampsia as compared with the term pregnant controls had significantly higher (P = 0.04) median amniotic fluid C3a levels (318.7 versus 254.5 ng/mL) | (215) |
| C3a | 751.6 (194.6–1,660) vs. 1,358 (854.8–2,142) ng/mL, P < 0.05 preeclamptic vs. healthy pregnant | (222) |
| C3a, C3a_desArg, and C5a | Elevated at term in PE but not earlier (P < 0.05) | (223, 224) |
| C3a, C5a, and AT1-AA | Levels in serum from the severe preeclampsia group were significantly higher than in controls (P < 0.05) | (225) |
| C4 | C4 was lowered (P < 0.001) in serum of term preeclamptics | (226) |
| C4d | Placental immunochemistry showed that C4d was rarely present in placentas from healthy controls (3%), whereas it was observed in 50% of placentas obtained from preeclamptic women (P = 0.001) | (210) |
| C5a | The mean cord plasma C5a concentration was higher in patients with PE (8.3 ± 1.71 ng/ml) than normal women (3.2 ± 0.35 ng/ml) P < 0.01 | (212) |
| C5b-9 | Severe preeclampsia was associated with marked elevations in urinary C5b-9 [median and interquartile range, 4.3 (1.2–15.1) ng/mL] relative to subjects with chronic hypertension and healthy controls (P < 0.0001) | (227) |
| C6 | Novel evidence that genetic variations in complement genes C6 and MASP1 were associated with preeclampsia risk | (217) |