Downregulation of peroxisome proliferator-activated receptor-gamma expression in hypertensive atrial fibrillation

Numerous evidence has suggested that either hypertension or atrial fibrillation (AF) is associated with systemic inflammation. Peroxisome proliferator-activated receptor-gamma (PPARgamma) has been proved to have anti-inflammatory effects and is implicated as a molecular pathway involved in many cardiovascular diseases, such as hypertension. The correlation between PPARgamma inflammation and AF is still unknown.

Using a case-control study design, 57 patients with hypertensive AF (persistent AF: 32, paroxysmal AF: 25) were included into the study groups. A total of 32 age-matched patients with hypertension, but without AF were selected as the control group. The expressions of PPARgamma, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) mRNA in monocytes were detected by using a reverse transcription-polymerase chain reaction (RT-PCR). Interleukin-1 (IL-1) was measured by immunoenzymetric methods.

The PPARgamma mRNA was markedly decreased in the hypertensive AF group as compared with the hypertensive non-AF group, and it was significantly lower in persistent AF than paroxysmal AF (0.222 +/- 0.0702 vs 0.564 +/- 0.0436, P<0.01). TNF-alpha mRNA, IL-6 mRNA, and IL-1 were increased in patients with hypertensive AF compared to the non-AF group and it was even higher in persistent AF than in paroxysmal AF (0.721 +/- 0.0541 vs 0.530 +/- 0.0496, 0.567 +/- 0.044 vs 0.457 +/- 0.0505, 325.61 +/- 88.10 vs 190.65 +/- 59.38, respectively, P<0.01). TNF-alpha, IL-6, and IL-1 were in negative correlation with PPARgamma, the correlation coefficient was -0.854, -0.769, and -0.702, respectively (P<0.01).

In hypertensive patients, increased inflammatory cytokines were associated with increased incidence of AF and atrial remodeling; PPARgamma may be involved in the pathogenesis of AF by regulation of inflammation.