Telmisartan ameliorates
inflammation in various
brain disorders through
angiotensin II type 1 receptor (AT1) blockade and
peroxisome proliferator-activated receptor gamma (PPARγ) activation. Soluble β-
amyloid oligomers (AβOs) play a causative role in neuronal dysfunction and
memory loss in
Alzheimer's disease. In addition to directly targeting neurons, AβOs may also activate microglia to trigger toxic proinflammatory responses. Here, we investigated whether and how
telmisartan ameliorates inflammatory responses in AβO-stimulated microglia. A mouse-derived BV2 microglial cell line lacking AT1 expression was selected as an in vitro model.
Telmisartan not only inhibited AβO-induced proinflammatory
interleukin (IL)-1β and
tumor necrosis factor-α (TNF-α) expression, but also increased anti-inflammatory
IL-10 expression, which was not affected by AβO stimulation.
Telmisartan also inhibited AβO-induced nuclear factor (NF)-κB activity and phosphorylation of Akt and ERK, two upstream regulators of NF-κB activation. These anti-inflammatory effects were antagonized by PPARγ inhibitor
GW9662. In addition,
telmisartan increased the expression of PTEN (
phosphate and
tensin homolog deleted on chromosome 10), a
lipid and
protein phosphatase; PPARγ inhibitor
GW9662 reversed this effect, indicating that
telmisartan-induced PTEN expression is PPARγ dependent. The PTEN inhibitor blocked the effects of
telmisartan on Akt and ERK phosphorylation, NF-κB transcriptional activity, and IL-1β and TNF-α production, but failed to reverse
IL-10 expression. This data indicates that
telmisartan-induced
IL-10 expression is PPARγ-dependent but PTEN-independent. Altogether,
telmisartan ameliorated AβO-induced microglial
inflammation by inhibiting NF-κB-mediated proinflammatory
cytokine expression via the PPARγ/PTEN pathways and by increasing PPARγ-mediated anti-inflammatory
IL-10 expression.
Telmisartan may present a promising
therapy for the treatment of AβO pathology.