Abstract 15468: Cd81 Interacts With Sodium Chloride Cotransporter in Lps-Induced Preeclampsia Rats and in Cultured Mouse Renal Distal Convoluted Tubule Cells

Kidney regulates blood pressure mainly through salt/water reabsorption affected by sodium transport proteins along nephron. We have reported that placental CD81 plays an important role in the pathogenesis of preelampsia. In order to explore the connection between CD81 and renal sodium transport proteins in preelampsia, we studied their interactions in vivo and in vitro. On the gestation day 18 of lipopolysaccharide-induced preeclamsia model rats with hypertension and albuminuria, the renal protein abundances of NKCC2 (150±14,% of control, n=5-6/group, mean±SE, t-test, same as below), p-NKCC2(567±70%), NCC (254±41) and WNK4 (196±12) were increased together with an increase of CD81 in kidney (225±46) and urinary exosomes(396±100). Renal NCC (215±30) was elevated while NKCC2 tended to increase at 17000g pellet in LPS group. There was no change of both NKCC2 and NCC at 200,000g pellet. In kidney homogenates, CD81 was coimmunoprecipitated with NKCC2, NCC, not NHE3 while NKCC2, NCC were coimmunoprecipitated with CD81 not CD63. In renal plasma-membrane-enriched fraction NCC, not NKCC2, was also increased in preeclampsia rats. In the apical membrane of renal tubules CD81 was colocalized with NCC while minimum colocalization was found between CD81 and NKCC2. In cultured mouse distal convoluted tubule cells, CD81 was colocalized with NCC while CD81 deletion with siRNA decreased NCC and partially reversed lipopolysaccharide-induced increase of NCC. Furthermore, CD81 was detected only in the urinary exosomes from preeclampsia patients along with increases in NKCC2 (6063±811) and NCC(1085±191)relative to normal pregnant women (n=6/group, t-test). Those findings suggest that CD81 interacts with renal NCC in vivo and in vitro and the increase of renal CD81 may up-regulate NCC, possibly NKCC2 as well, and contribute to the increased blood pressure in preeclampsia.