Altered Production and Cellular Levels of Hydrogen Sulfide (H(2)S) in Placental Trophoblasts from Pregnancies Affected by Pre-Eclampsia.

BACKGROUND/OBJECTIVES: Hydrogen sulfide (H(2)S) is a vasorelaxant gas and exerts anti-oxidative, anti-inflammatory, and cytoprotective effects. H(2)S has been implicated in regulating placental vaso-activity and angiogenesis. It is believed that abnormal trophoblast production of vasodilators and angiogenic factors contributes to pre-eclampsia development. However, little is known about whether aberrant H(2)S production is present in placental trophoblasts from pre-eclamptic pregnancies. METHODS: Trophoblasts were isolated from normal and pre-eclamptic placentas. After incubation, cell production of H(2)S in the culture medium and the cellular levels of H(2)S were analyzed by reversed phase high-performance liquid chromatography (RP-HPLC). Expression levels of the three key H(2)S converting enzymes, cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST), were determined by immunohistochemistry. The protein expression of CBS and CSE was assessed by Western blot analysis. RESULTS: (1) Trophoblast production and cellular levels of H(2)S were significantly reduced in cells from pre-eclamptic vs. normal placentas; (2) free H(2)S production was increased in a time-dependent manner in cultured trophoblasts from normal, but not from pre-eclamptic, placentas; and (3) strong CBS and CSE expression was seen in trophoblasts from normal, as opposed to pre-eclamptic, placentas. Reduced CBS and CSE expression in trophoblasts from pre-eclamptic vs. normal placentas were confirmed by Western blot analysis; and (4) 3-MST expression was undetachable in both normal and pre-eclamptic placentas, but 3-MST expression was strongly expressed in the first and second trimester placentas. CONCLUSIONS: These data provide plausible evidence that downregulation of CBS and CSE, but not 3-MST, expression may be responsible for reduced free H(2)S production and decreased cellular H(2)S levels in pre-eclamptic placentas. Our data provide further evidence that expression of 3-MST in placental trophoblasts is likely gestational age (developmental)-dependent.