Placental leptin in HIV-associated preeclampsia

HIV-associated preeclampsia reflects a combination of opposing influences on the immune status. The adipocyte hormone leptin has been implicated in the pathophysiology of preeclampsia and in enhancing immunity. This study is the first, to our knowledge, to determine whether leptin levels in the placenta differ between HIV-associated normotensive and preeclamptic pregnancies. The study also compares leptin levels between the exchange and conducting areas of the placenta.

Pregnant women were recruited antenatally and grouped as follows: normotensive HIV uninfected (n=30), normotensive HIV infected (n=60), preeclamptic HIV uninfected (n=30) and preeclamptic HIV infected (n=60). Anthropometric data were collected and placental leptin was analysed by immunohistochemistry and ELISA.

Leptin levels were similar in the central and peripheral regions of the placenta. Leptin immunoreactivity was observed amongst the different trophoblast cell populations. Both ELISA and immunohistochemistry of the placental exchange villi indicated that leptin levels were higher in preeclampsia compared to normotensive pregnancies (p<0.001). HIV status had no effect on leptin levels but levels were higher in participants on highly active antiretroviral treatment (HAART) compared to those on prophylaxis for prevention of mother to child transmission (PMTCT) with normotensive (p=0.006) and preeclamptic (p=0.002) pregnancies. The area of immunostaining was greater in the exchange compared to the conducting villi in HIV infected and uninfected preeclampsia.

This novel study establishes an elevation of leptin in preeclamptic placentae, irrespective of HIV status. Leptin elevation was not focal in that it occurred in both central and peripheral regions of the preeclamptic placenta. This suggests a role of leptin in the pathophysiology of preeclampsia.