Expression of mitochondrial thioredoxin-dependent antioxidant protein, SP-22, in normal human and inflammatory mouse placentae

The aim of this study was to elucidate whether a novel mitochondrial antiox idant protein, SP-22, is localized in placenta and whether its expression i s induced in placenta of lipopolysaccharide (LPS)-exposed mouse. Western bl ot analysis of normal human placenta indicated that the SP-22 protein was l ocated in the mitochondrial fraction. Immunohistochemical analysis of SP-22 in normal placenta showed that immunoreactive SP-22 was distributed mostly in cytotrophoblastic cells but with almost no signal in syncytiotrophoblas ts. The positive signals were also detected in the decidual cells and strom al cells in stem villi of normal placenta. We also examined LPS-mediated in flammatory placenta on day 13 of pregnancy at various time points after LPS injection (50 mug/kg, intraperitoneally). Western blot analysis indicated that LPS approximately quadrupled the expression of SP-22 in placenta of LP S-exposed mouse. When the SP-22 protein was localized immunohistochemically , the decidua and the diploid trophoblasts in the basal zone were intensive ly stained in placenta of LPS-exposed mouse compared to the control. The lo calization and inducible expression of SP-22 protein in placenta suggest a possible role in antioxidant system in mitochondria of normal and inflammat ory placentae. (C) 2000 Harcourt Publishers Ltd.