Abstract 035: Cholinergic Agonists Protect from the Development of Hypertension during Chronic Inflammatory Disease

Abstract

Systemic lupus erythematosus (SLE) is an autoimmune disorder with prevalent hypertension. Previous studies using a genetic mouse model of SLE (NZBWF1) suggest chronic inflammation is an important contributor to SLE hypertension. A novel neuroimmune pathway involving the α7 subunit of the nicotinic acetylcholine receptor (α7nAChR) suppresses splenic cytokine release and reduces systemic inflammation upon stimulation. To test whether activation of this ‘cholinergic anti-inflammatory pathway’ at the level of the α7nAChR attenuates the development of hypertension during SLE, female SLE and control (NZW) mice were infused with nicotine hydrogen tartrate salt (2 mg/kg/day, SC) or saline for 7 days. Nicotine-treated SLE mice had lower splenic protein expression of TNF-α and IL-6 (normalized to β-actin) relative to saline-treated SLE mice (1.09±0.06 vs. 1.37±0.06 and 0.36±0.04 vs. 0.55±0.10; all p<0.05), suggesting efficacy of the therapy. Mean arterial pressure (MAP; mmHg) was increased in SLE mice compared to controls (140±4 vs. 114±2; p<0.001). Nicotine prevented the rise in MAP in SLE mice (129±4; p=0.022), but not controls (121±3). This protection from hypertension coincided with a 46±5% lower renal cortical TNF-α in nicotine-treated SLE mice compared to saline-treated SLE mice (0.39±0.04 vs. 0.73±0.18), which is important because it has been previously shown that renal TNF-α plays a mechanistic role in the development of hypertension during SLE. Because nicotine acts on both ganglionic and peripheral cholinergic receptors, in a subsequent study mice were administered the selective α7nAChR agonist, PNU-282987 (0.38 mg/kg/day, IP), or vehicle for 28 days. PNU-282987-treated SLE mice had lower splenic protein expression of TNF-α and IL-6 relative to saline-treated SLE mice (0.33±0.01 vs. 0.54±0.03 and 0.40±0.08 vs. 0.86±0.05; all p<0.05). MAP was increased in SLE mice compared to controls (138±2 vs. 122±5). PNU-282987 prevented the rise in MAP in SLE mice (128±4), but not controls (125±5). These data suggest the anti-inflammatory effects of cholinergic agonists may protect from SLE hypertension and that the cholinergic anti-inflammatory pathway may be an important target in hypertensive patients with chronic inflammatory diseases.