J. Liu et al., EXPRESSION OF TYPE-II NITRIC-OXIDE SYNTHASE IN PRIMARY HUMAN ASTROCYTES AND MICROGLIA - ROLE OF IL-1-BETA AND IL-1 RECEPTOR ANTAGONISTS, The Journal of immunology, 157(8), 1996, pp. 3569-3576
In this work, we studied the expression of type II nitric oxide syntha
se (NOS) in primary cultures of human astrocytes and microglia, Cytoki
ne-activated human fetal astrocytes expressed a 4.5-kb type II NOS mRN
A that was first evident at 8 h, steadily increased through 48 h, and
persisted through 72 h, The inducing signals for astrocyte NOS II mRNA
expression were in the order IL-1 beta + IFN-gamma > IL-1 beta + TNF-
alpha > IL-1 beta, SDS-PAGE analysis of cytokine-stimulated astrocyte
cultures revealed an approximately 130-kDa single NOS II band that was
expressed strongly at 48 and 72 h (72 h > 48 h), Specific NOS II immu
noreactivity was detected in cytokine-treated astrocytes, both in the
cytosol and in a discrete paranuclear region, which corresponded to Go
lgi-like membranes on immunoelectron microscopy, In human microglia, c
ytokines and LPS failed to induce NOS II expression, while the same st
imuli readily induced TNF-alpha expression, In cytokine-treated human
astrocytes, neither NOS II mRNA/protein expression nor nitrite product
ion was inhibited by TCF-beta, IL-4, or IL-10, In contrast, IL-1 recep
tor antagonist exerted near complete inhibition of NOS II mRNA and nit
rite induction, Monocyte chemoattractant peptide-1 mRNA was induced in
TGF-beta-treated astrocytes, demonstrating the presence of receptors
for TGF-beta in astrocytes. These results confirm that in humans, cyto
kines stimulate astrocytes, but not microglia, to express NOS II belon
ging to the high output nitric oxide system similar to that found in r
odent macrophages. They also show that the regulation of type II NOS e
xpression in human glia differs significantly from that in rodent glia
, A crucial role for the IL-1 pathway in the regulation of human astro
cyte NOS II is shown, suggesting a potential role for IL-1 as a regula
tor of astrocyte activation in vivo.