RESUMO
This work summarizes recent evidence that suggests that renal infiltration with immune cells plays a role in the pathogenesis of salt-sensitive hypertension. The presence of immunocompetent cells is a conspicuous finding in conditions associated with hypertension induced or maintained by a high salt intake. Studies in models of salt-sensitive hypertension following angiotensin II infusion and nitric oxide synthesis inhibition indicate that a reduction in the tubulointerstitial infiltration of lymphocytes and macrophages during the induction period results in protection from the subsequent development of salt-sensitive hypertension. Reduction of the renal immune infiltrate in spontaneously hypertensive rats results in near normalization of the blood pressure. The reduction in the immune infiltrate is associated with a reduction in the number of cells expressing angiotensin II (some of which are immune cells) and a reduction in renal oxidative stress. Since increased intrarenal angiotensin activity tends to reduce filtered sodium and increase sodium reabsorption, and the tubulointerstitial damage resulting from oxidative stress can induce a shift to the right in the pressure-natriuresis relationship, these findings suggest potential mechanisms by which the immune infiltrate could induce or worsen salt-driven hypertension.
Assuntos
Hipertensão/etiologia , Rim/patologia , Linfócitos/fisiologia , Cloreto de Sódio/farmacologia , Animais , Humanos , Hipertensão/imunologia , Hipertensão/prevenção & controle , Ácido Micofenólico/análogos & derivados , Ácido Micofenólico/farmacologia , Cloreto de Sódio/metabolismoRESUMO
Immunocompetent cells infiltrate the kidney in several models of experimental hypertension. We have previously shown that reduction of this infiltrate results in prevention of salt-sensitive hypertension induced by short-term angiotensin II infusion and nitric oxide inhibition (Quiroz Y, Pons H, Gordon KI, Rincón J, Chávez M, Parra G, Herrera-Acosta J, Gómez-Garre D, Largo R, Egido J, Johnson RJ, and Rodríguez-Iturbe B. Am J Physiol Renal Physiol 281: F38-F47, 2001; Rodríguez-Iturbe B, Pons H, Quiroz Y, Gordon K, Rincón J, Chávez M, Parra G, Herrera-Acosta J, Gómez-Garre D, Largo R, Egido J, and Johnson RJ. Kidney Int 59: 2222-2232, 2001). We therefore studied whether hypertension could be controlled in genetically hypertensive rats [spontaneously hypertensive rats (SHR)] by the administration of 20 mg x kg(-1) x day(-1) of the immunosuppressive drug mycophenolate mofetil (MMF group; n = 35). Other SHR received vehicle (n = 35), and Wistar-Kyoto rats (n = 20) were used as controls. MMF or vehicle was given in two separate 4-wk periods, separated by a 3-wk interval. Systemic hypertension was reduced to normal levels in both periods of MMF treatment in association with a reduction in lymphocyte, macrophage, and angiotensin II-positive cells infiltrating the kidney. Oxidative stress was also reduced by MMF, as indicated by a reduction in urinary malondialdehyde (MDA), renal MDA content, and superoxide-positive cells, and was highly correlated with blood pressure levels. We conclude that the renal immune infiltrate plays a major role in the hypertension in SHR.