Abstract P340: Immunomodulatory Effect of Rapamycin on the Expression of Anti-inflammatory Cytokines in Npr1 Gene-deleted Mice

Abstract

Disruption of natriuretic peptide receptor-A (NPRA) gene ( Npr1 ) activates the pro-inflammatory responses, which contributes to the pathogenesis of hypertension and end-organ damage. The objective of this study was to determine the kinetic responses of pro- and anti-inflammatory cytokines in Npr1 gene-knockout (KO) mice. Npr1 0-copy ( Npr1 -/- ), 1-copy ( Npr1 +/- ), and 2-copy ( Npr1 +/+ ) mice were pre-treated with rapamycin and multiplex analyses were done to assess cytokines levels. Pro-inflammatory cytokine, IFN-γ protein levels in plasma and kidney of 0-copy and 1-copy mice were markedly higher compared with 2-copy mice (76±1; 49±2 vs 32±1.3 pg/ml; 79±2; 29±1 vs. 27±0.5 pg/mg, respectively). Similarly, IL-6 levels in plasma and kidney were significantly elevated in 0-copy and 1-copy mice than 2-copy mice (52±1; 27±0.5 vs.12±0.4 pg/ml; 49±1.5; 38±2 vs.18±1.1 pg/mg, respectively). Interestingly, anti-inflammatory cytokine IL-5 protein levels in plasma and kidneys were significantly down-regulated in 0-copy and 1-copy mice than 2-copy mice (6±0.8; 5±0.1 vs. 12±0.5 pg/ml; 6±0.6; 9±0.4 vs. 28±0.5 pg/mg). IL-10 levels in plasma and kidney of 0-copy and 1-copy mice were also significantly decreased than 2-copy mice (22±0.4; 39±1 vs. 62±3 pg/ml; 14±1.7; 36±0.2 vs. 52±3 pg/mg). Rapamycin significantly reduced the levels of IFN- γ in plasma and kidney of 0-copy (50%, 35%) and 1-copy (63%, 55%) mice and IL-6 level in 0-copy (60%, 38%) and in 1-copy (40%, 26%) mice compared with 2-copy mice. In contrast, rapamycin treatment significantly elevated IL-5 levels in plasma and kidneys of 0-copy (68%, 77%) and 1-copy (61%, 64%) mice and IL-10 levels in 0-copy (80%, 78%) and 1-copy (47%, 25%) mice than 2-copy mice. A significant decrease in blood pressure occurred in rapamycin-treated 0-copy (19±4 mmHg) and 1-copy (12±3 mmHg) mice than untreated control mice. The results demonstrate that the expression of pro-inflammatory cytokines is greatly upregulated in Npr1 KO mice compared with 2-copy mice and rapamycin serves as the immune modulator of anti-inflammatory cytokines in these animals. The present findings implicate that rapamycin might act as an anti-inflammatory drug for the treatment of pathophysiology of hypertension-associated inflammation.