Tumor Necrosis Factor α Blockade Increases Renal Cyp2c23 Expression and Slows the Progression of Renal Damage in Salt-Sensitive Hypertension

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Abstract
We hypothesized that the downregulation of Cyp2c by tumor necrosis factor (TNF) α contributes to hypertension and renal injury in salt-sensitive angiotensin hypertension. Male Sprague-Dawley rats were fed a high-salt diet (8% NaCl), and osmotic minipumps were implanted to deliver angiotensin II for 14 days. Rats were divided into 3 groups: high salt, angiotensin high salt, and angiotensin high salt administered the TNF-α blocker, etanercept. Arterial pressure increased from 94±5 to 148±7 mm Hg during week 1 in the angiotensin high-salt group, whereas etanercept slowed blood pressure elevation during the first week in the treated group (90±2 to 109±6 mm Hg). After 2 weeks, arterial pressure increased to 156±11 mm Hg in the angiotensin high-salt group and 141±6 mm Hg in the etanercept-treated group. Albuminuria and proteinuria were significantly elevated in angiotensin high-salt rats and were reduced in the etanercept-treated rats. Urinary monocyte chemoattractant protein-1 excretion significantly increased in the angiotensin high-salt group (275±47 versus 81±19 ng/day) and was decreased in the etanercept-treated group (153±31 ng/day). Angiotensin high-salt rats also had a significant increase in renal monocyte/macrophage infiltration, and this was again attenuated by etanercept treatment. Renal expression of Cyp2c23 decreased, whereas renal epoxide hydrolase expression increased in angiotensin high-salt rats. Etanercept treatment increased Cyp2c23 expression and lowered epoxide hydrolase expression. These data suggest that TNF-α contributes to downregulation of Cyp2c23, blood pressure regulation, and renal injury in angiotensin high-salt hypertension.