Abstract P262: Vasopressin Receptors Regulate Immune Responses in Preeclampsia

The pathogenesis of preeclampsia (PE) involves imbalanced T helper (T H ) cell populations and resultant changes in pro- and anti-inflammatory cytokine release. Elevated secretion of arginine vasopressin (AVP) precedes the development of symptoms in PE in humans, and chronic infusion of AVP (24 ng/hr s.c.) throughout gestation is sufficient to initiate cardiovascular, renal, and immune phenotypes of PE in wild-type C57BL/6J mice. We hypothesize that increased AVP signaling may mediate the immune changes observed in PE. AVP infusion throughout gestation in mice resulted in increased pro-inflammatory IFNγ (T H 1) in the maternal plasma (N=7, p<0.05) and IL-17 (T H 17) in the placenta (N≥10, p<0.001). The T H 2-associated anti-inflammatory cytokines IL-4 and IL-10 were decreased in maternal kidney (IL-4: N=8, p<0.05; IL-10: N=5, p<0.01) and fetal kidney (IL-4: N=5, p<0.05; IL-10: N=5, p<0.05) of AVP-infused dams. To elucidate the receptor dependency of these effects, AVP-infused dams were simultaneously treated with chronic infusion of AVP V 1A and/or V 2 receptor antagonists (22 ng/hr s.c). Combined blockade of V 1a +V 2 receptors by conivaptan, as well as specifically blocking V 2 by tolvaptan, corrected AVP induced reductions in IL-4 in maternal (conivaptan: N=5, p<0.05; tolvaptan: N=5, p<0.0.0001) and fetal kidneys (conivaptan: N=5, p<0.0001; tolvaptan: N=5, p<0.05). These data implicate V 2 as the receptor involved in kidney IL-4 deficiency in PE, whereby blockade of V 2 restores IL-4, preventing inflammation. Combined blockade of V 1A +V 2 receptors by conivaptan corrected the placental loss of IL-4 (N=5, p<0.05), whereas blockade of either receptor alone was insufficient, suggesting loss of placental IL-4 via AVP is mediated by both V 1a and V 2 receptors. In contrast, increased placental IL-17 was only corrected by selective blockade of V 1A by relcovaptan (N=5, p<0.05), suggesting a novel role for V1a receptor in pro-inflammatory placental IL-17 production in PE. Collectively these results demonstrate the sufficiency of AVP to induce the immune changes typical of PE, and support a dominant role for V 1A in the induction of pro-inflammatory IL-17 (T H 17) release versus a dominant role for V 2 receptors in the suppression of anti-inflammatory IL-4 (T H 2) release.