With increased industrial development,
cadmium is an increasingly important
environmental pollutant. Studies have identified various adverse effects of
cadmium on human beings. However, the relationships between
cadmium pollution and the pathogenesis of
preeclampsia remain elusive. The objective of this study is to explore the effects of
cadmium on immune system among preeclamptic patients and rats. The results showed that the
cadmium levels in the peripheral blood of preeclamptic patients were significantly higher than those observed in normal pregnancy. Based on it, a novel rat model of
preeclampsia was established by the intraperitoneal administration of
cadmium chloride (CdCl2) (0.125 mg of Cd/kg
body weight) on gestational days 9-14. Key features of
preeclampsia, including
hypertension,
proteinuria, placental abnormalities and small foetal size, appeared in pregnant rats after the administration of low-dose of
CdCl2.
Cadmium increased
immunoglobulin production, mainly
angiotensin II type 1-receptor-agonistic
autoantibodies (AT1-AA), by increasing the expression of activation-induced
cytosine deaminase (AID) in B cells. AID is critical for the maturation of antibody and
autoantibody responses. In addition,
angiotensin II type 1-receptor-agonistic
autoantibody, which emerged recently as a potential pathogenic contributor to PE, was responsible for the deposition of
complement component 5 (C5) in kidneys of pregnant rats via
angiotensin II type 1 receptor (AT1R) activation. C5a is a fragment of C5 that is released during C5 activation. Selectively interfering with C5a signalling by a
complement C5a receptor-specific antagonist significantly attenuated
hypertension and
proteinuria in Cd-injected pregnant rats. Our results suggest that
cadmium induces immune abnormalities that may be a key pathogenic contributor to
preeclampsia and provide new insights into treatment strategies of
preeclampsia.