Renoprotective effects of long-term oral nicotine in a rat model of spontaneous proteinuria

Many proteinuric renal conditions are accompanied by renal inflammation. Nicotine is known to have anti-inflammatory properties and is used in oral form to help subjects quit smoking. A potential anti-inflammatory role of nicotine in proteinuric renal diseases has not been investigated to date. We therefore evaluated the effects of oral nicotine in a rat model of proteinuria-induced renal inflammation. We used a well-established model of adult (24 wk of age) male Munich-Wistar-Frömter rats. Animals were given three different physiological doses of nicotine in drinking water for 28 wk until 52 wk of age (long term). A group without nicotine served as a parallel control. At 52 wk of age, the control group had a 2.1 times reduction in creatinine clearance, 3.2 times increase in urinary protein excretion, an increased focal glomerulosclerosis (FGS) score, increased glomerular desmin deposition, decreased glomerular podocin, and a higher accumulation of macrophages and myofibroblasts compared with 24-wk-old animals. Oral treatment with nicotine dose dependently preserved renal function and halted proteinuria progression, which were independent of blood pressure reduction. It also reduced FGS, desmin deposition, podocin loss, and density of renal macrophages and myofibroblasts. Nicotine also reduced the level of gene expression of the renal inflammatory markers monocyte chemoattractant protein and vascular cell adhesion molecule-1. In conclusion, long-term oral nicotine preserved kidney function, reduced proteinuria, reduced renal inflammation, and protected progression of renal structural damage in a rat model of proteinuria. We further suggest evaluating nicotine as a potential additional therapeutic option for treating proteinuric kidney diseases.