Angiotensin type 1 receptor antagonist inhibits lipopolysaccharide-induced stimulation of rat microglial cells by suppressing nuclear factor kappa B and activator protein-1 activation

作者：Miyoshi Michio; Miyano Kanako; Moriyama Naoki; Taniguchi Makoto; Watanabe Tatsuo^*

来源：European Journal of Neuroscience, 2008, 27(2): 343-351.

DOI：10.1111/j.1460-9568.2007.06014.x

• angiotensin II
• cytokine
• lipopolysaccharide
• microglia
• nuclear factor kappa B

We investigated whether angiotensin (ANG) II and its receptors contribute to lipopolysaccharide (LPS)-induced microglial activation through activation of the proinflammatory transcription factors nuclear factor kappa B (NF-kappa B) and activator protein-1 (AP-1). Using primary microglial cell cultures, we examined whether losartan [ANG type 1 receptor (AT(1)) antagonist] alters the effects of LPS on: the production of interleukin-1 (IL-1) and nitric oxide, cell morphology, and NF-kappa B and AP-1 activities. Reverse transcription-polymerase chain reaction revealed that LPS-stimulated microglial cells exhibited marked mRNA expression for AT(1), ANG type 2 receptor (AT(2)) and the ANG II precursor angiotensinogen, whereas non-stimulated microglial cells expressed only those for AT(2) and angiotensinogen. We further demonstrated marked peptide/protein expression for AT(1) and ANG II in LPS-activated microglial cells. LPS (100 ng/mL)-stimulated microglial cells showed increased concentrations of IL-1 and nitrite (a relatively stable metabolite of nitric oxide), and increased expression of IL-1 mRNA as well as a morphological change from an amoeboid shape to a multipolar (mostly bipolar but sometimes tripolar) rod shape. These effects were all significantly inhibited by losartan treatment (10(-5) M or less). NF-kappa B and AP-1 activities were enhanced in LPS-stimulated microglial cells, effects that were significantly suppressed by losartan (10(-5) M). ANG II application enhanced the LPS-induced increases in IL-1 and nitrite concentrations, as well as the LPS-induced morphological changes and AP-1 activation, and these enhancements were inhibited by losartan (10(-5) M). These results suggest that endogenous ANG II enhances LPS-induced microglial activities through stimulation of the microglial AT(1), which itself evokes activation of the transcription factors NF-kappa B and AP-1.

• 出版日期2008-1