Abstract 182: Reduction in Interleukin-10 Level in Plasma and in Renal Tissue During Systemic Inhibition of Nitric Oxide Synthase in Anesthetized Mice
Systemic inhibition of nitric oxide synthase (NOS) in mice increased tumor necrosis factor-alpha (TNFα) level in plasma. The present study examined the hypothesis that an inhibition of interleukin-10 (IL-10; anti-inflammatory cytokine) in response to NOS inhibition facilitates such enhancement in TNFα production. Levels of IL-10 and TNFα were measured (using ELISA kits) in plasma and in renal tissues obtained from anesthetized mice (C57BL6; ∼10 wks age) infused with or without NOS inhibitor, nitro-L-arginine methyl ester (L-NAME; 200 μg/min/kg, iv). Protein expressions of IL-10 and TNFα in the renal tissues were also measured by immuno-staining. L-NAME infusion alone for 130 min (n=6) resulted in decreased IL-10 levels in plasma (0.3±0.1 vs 2.6±0.6 ng/mL) and in renal tissue (0.5±0.1 vs 1.3±0.1 ng/mg protein) which were associated with increased TNFα levels in plasma (432±82 pg/mL vs undetected) and in renal tissue (58±7 vs 6±5 pg/mg protein) as compared to vehicle treated control mice (n=6). There was marked down-regulation of IL-10 protein expression (present only in the distal tubules in control mice) and up-regulation of TNFα protein expression (distal tubules and collecting ducts) in the renal tissues in L-NAME treated mice. Infusion of NO donor, S-nitroso-N-acetyl-penicillamine (SNAP; 25 μg/min/kg for 75 min) in a separate group of L-NAME treated mice (n=6) restored the IL-10 level in plasma (1.0±0.1 ng/mL) and in renal tissue (1.5±0.1 ng/mg protein) closer to the values in control mice indicating that L-NAME induced IL-10 responses are specific to NO inhibition. SNAP infusion in L-NAME treated mice also reduced TNFα level in plasma (to an undetected level) and in renal tissue (20±4 pg/mg protein) along with its protein immune-expression. Infusion of mouse IL-10 (0.075 ng/min/g for 75 min) in another separate group of L-NAME treated mice (n=7) also attenuated TNFα level in plasma (50±16 pg/mL) and in renal tissue (21±7 pg/mg protein) along with its protein immune-expression indicating that L-NAME induced TNFα responses are specific to reduction in IL-10 level. The results demonstrate that systemic NOS inhibition decreases IL-10 production and thus, minimizes its immune down-regulating action on the production of TNFα, particularly in the kidney.
- © 2012 by American Heart Association, Inc.