Expression of transforming growth factor-β1 in periventricular leukomalacia

The expression of transforming growth factor-beta 1, which has neurotrophic effects, was investigated in 25 neonates with periventricular leukomalacia using immunohistochemistry. In controls, transforming growth factor-beta 1 immunoreactivity was not detected in the cerebral white matter or cortex. Of the 25 cases of periventricular leukomalacia, transforming; growth factor-beta 1 immunoreactivity was found in 16, and was distributed mainly in the cytoplasm of astrocytes, being prominent around necrotic foci in the white matter. The immunoreactivity was negative or weak at the acute stage of periventricular leukomalacia, and increased at the subacute stage and then decreased or was absent at the chronic stage. Astrocytes that were moderately or markedly positive for transforming growth factor-beta 1 were not found before 27 weeks' gestation, but were observed after 32 weeks' gestation in the white matter of the brains of neonates with periventricular leukomalacia. Transforming growth factor-beta 1 expression tended to be more obvious in focal periventricular leukomalacia than in widespread or diffuse periventricular leukomalacia. Our results suggest that transforming growth factor-beta 1 could be involved in the delayed glial response rather than the initial glial activation, and could play a role in the inhibition and repair of injury in periventricular leukomalacia. Exogenous transforming growth factor-beta 1 could have therapeutic potential for periventricular leukomalacia.