High-dose treatment with telmisartan induces monocytic peroxisome proliferator-activated receptor-γ target genes in patients with the metabolic syndrome.

The present study aimed to explore the anti-inflammatory effects and peroxisome proliferator-activated receptor-γ (PPARγ)-activating properties of the angiotensin type 1 receptor blocker telmisartan by analysis of serum interleukin 6 levels and monocytic PPARγ target gene expression in drug-naïve patients with the metabolic syndrome. This was a 14-week, randomized, double-blind, placebo-controlled 2-center study with telmisartan 80 mg/d and telmisartan 160 mg/d in 54 patients with the metabolic syndrome. In addition to clinical laboratory measurements, peripheral monocytes were extracted by negative isolation using a Dynal Monocyte kit to evaluate ligand-activated PPARγ target gene expression (CD36 and CD163) at baseline and study end using quantitative real-time RT-PCR. In this low-risk patient population, telmisartan (80 and 160 mg) treatment did not significantly affect serum interleukin 6 levels. Expression of the PPARγ target gene CD36 in monocytes was markedly induced by telmisartan from baseline to study end (telmisartan 80 mg: 2.3±1.5-fold change versus placebo [P value not significant]; telmisartan 160 mg: 3.5±0.9-fold change versus placebo [P<0.05]). The recently reported PPARγ target gene CD163 was slightly induced by telmisartan (telmisartan 80 mg: 1.1±0.3-fold change versus placebo [P value not significant]; telmisartan 160 mg: 1.4±0.4-fold change versus placebo [P value not significant]), which did not reach statistical significance. This is the first clinical description of monocytic PPARγ target gene regulation with high-dose telmisartan treatment. These data implicate that the angiotensin type 1 receptor blocker telmisartan activates PPARγ in circulating monocytes of patients with the metabolic syndrome.

Chronic treatment with losartan results in sufficient serum levels of the metabolite EXP3179 for PPARgamma activation.

The losartan metabolite EXP3174 exhibits angiotensin II receptor 1 (AT1R)-blocking properties, whereas the metabolite EXP3179 potently induces the activity of the insulin-sensitizing peroxisome proliferator-activated receptor gamma (PPARgamma) as a partial agonist in vitro. We investigated whether chronic treatment with losartan leads to sufficient serum levels of EXP3179 to activate PPARgamma in monocytes derived from losartan-treated patients. Hypertensive patients (n=15) treated with losartan (100 mg/daily for at least the past 2 months) and untreated control patients (n=7) were included. Monocytes were extracted by negative isolation using a Dynal Monocyte Kit, followed by analysis of PPARgamma target gene expression (CD36, ABC transporter G1 [ABCG1]) by quantitative real-time RT-PCR. Serum was prepared before, 2, 4, and 6 hours after losartan (100 mg) ingestion for HPLC-based determination of losartan, EXP3174, and EXP3179. Chronic treatment with losartan resulted in basal levels of losartan, EXP3174, and EXP3179 of 348.3+/-101.8 ng/mL, 115.3+/-56.1 ng/mL, and 176.2+/-143.4 ng/mL, respectively. Levels of both EXP3174 and EXP3179 were time-dependently increased in serum with a maximum 2 hours after drug intake (1706.0+/-760.1 ng/mL, 808.9+/-618.2 ng/mL, respectively). In consonance with detectable PPARgamma-activating EXP3179 serum levels, monocytic PPARgamma target gene expression was significantly upregulated in patients treated with losartan by 3.75+/-0.95- and 252.02+/-46.86-fold for CD36 and ABCG1 (P=0.043, P=0.0045 versus control patients, respectively). This is the first clinical description of monocytic PPARgamma-target gene regulation by chronic treatment with losartan, which likely is mediated by its metabolite EXP3179. Our data show that sufficient serum levels of EXP3179 are present under losartan treatment. PPARgamma activation by AT1R-blockers may translate into synergistic beneficial actions in monocytes.