Altered Production and Cellular Levels of Hydrogen Sulfide (H2S) in Placental Trophoblasts from Pregnancies Affected by Pre-Eclampsia.

BACKGROUND/

OBJECTIVES

Hydrogen sulfide (H2S) is a vasorelaxant gas and exerts anti-oxidative, anti-inflammatory, and cytoprotective effects. H2S 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 H2S 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 H2S in the culture medium and the cellular levels of H2S were analyzed by reversed phase high-performance liquid chromatography (RP-HPLC). Expression levels of the three key H2S 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 H2S were significantly reduced in cells from pre-eclamptic vs. normal placentas; (2) free H2S 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 H2S production and decreased cellular H2S levels in pre-eclamptic placentas. Our data provide further evidence that expression of 3-MST in placental trophoblasts is likely gestational age (developmental)-dependent.