Overexpression of HGF transgene attenuates renal inflammatory mediators, Na(+)-ATPase activity and hypertension in spontaneously hypertensive rats.

Renal inflammation and oxidative stress are constantly present in experimental hypertension. Since the spontaneously hypertensive rat (SHR) has reduced levels of hepatocyte growth factor (HGF), which suppresses the activation of the proinflammatory nuclear transcription factor kappa B (NF-κB), we speculated that HGF deficiency could play a key role in the pathogenesis of hypertension in the SHR. To test this hypothesis we increased HGF in the SHR by HGF gene delivery. We found that kidneys of 15-week-old SHR had an important reduction in HGF mRNA and protein expression. Adult SHRs were randomly assigned to receive weekly hydrodynamic injection (1mg/kg) of a naked plasmid containing human HGF (hHGF) gene associated with a cytomegalovirus promoter (pCMV-HGF) or empty vector (pcDNA3.1) during 6weeks. WKY rats treated with pcDNA3.1 and pCMV-HGF served as controls. The kidneys in the hypertensive SHR untreated and treated with the empty vector had increased NF-κB activation, elevated mRNA and protein expression of RANTES, MCP-1 and IL-6 and increased oxidative stress. Activity of Na(+)-ATPase was increased while activity of Na(+), K(+)-ATPase was normal. hHGF gene therapy normalized renal NF-κB activity, proinflammatory cytokines, antioxidant status (GSH, SOD and CAT), Na(+)-ATPase activity, reduced renal injury and ameliorated hypertension. Our results suggest that reduction in HGF production plays a major role in the pathogenesis of hypertension in the SHR and increasing HGF is a potential therapeutic target in the treatment of hypertension.

HLA class I association with progression to end-stage renal disease in patients from Zulia, Venezuela

The aim of this study was to determine HLA associations with progression to end-stagerenal disease (ESRD) in the mixed Zulian population in Venezuela, regardless of other factors. A retrospective study to determine HLA Class I association was performed on188 patients with ESRD due to different types of glomerulonephritis, and 202 healthy controls. Patients and control groups were serologically typed by Terasaki microlymphocytotoxicity technique using commercial Class I plates including 26 HLA-A and 48 HLA-Bspecificities. The antigens positively associated to the ESRD were: HLA-B38, B51, B53 and B62.Negatively associated antigens were: HLA-A9, B12, B17, B40 and B48. The haplotypes positively associated were: HLA-A2-B51, A2-B53, A23-B38 and A68-B38. The negatively associated haplotypes were: HLA-A2-B12, A2-B48, A9-B35 and A28-B40. The high Odds ratio observed and its statistical corroboration reflect the strength of the described association between HLA antigens and ESRD. Further molecular studies should clarify types and subtypes of the HLA class I alleles involved in the progression to ESRD (AU)

El objetivo principal de este trabajo fue determinar las posibles asociaciones de los antígenos HLA con la progresión a enfermedad renal terminal (ESRD por las siglas en inglés), independientemente de otros factores, en la población Zuliana de Venezuela. Se trata de un estudio retrospectivo, analizando los resultados obtenidos de la tipificación de los antígenos HLA clase I (A y B) en 188 pacientes con enfermedad renal crónica en etapa terminal y con indicación de trasplante renal, en comparación con 202 controles sanos de la misma población. Los antígenos HLA fueron tipificados por la técnica de microlinfocitotoxicidad de Terasaki, utilizando placas comerciales para clase I incluyendo 26 especificidades HLAA y 48 HLA-B. Los antígenos HLA clase I asociados a ESRD fueron: HLA-B38, B51, B53,B62; y los asociados negativamente resultaron HLA-A9, B12, B17, B40, B48. Los haplotipos asociados positivamente fueron: HLA-A2-B51, A2-B53, A23-B38 y A68-B38. Los haplotipos asociados negativamente resultaron: HLA-A2-B12, A2-B48, A9-B35, A28-B40. Los altosriesgos relativos observados y su corroboración estadística reflejan la fortaleza de las asociaciones descritas. Estos resultados podrían orientar los estudios moleculares que permitirán determinar y confirmar de manera más específica cuáles son los alelos HLA clase I asociados con esta patología (AU)

Effect of uric acid on hypertension progression in spontaneously hypertensive rats.

AIMS: We investigated the effects of soluble uric acid (UA) on the development of hypertension in spontaneously hypertensive rats (SHRs), using Wistar-Kyoto rats (WKY) as normotensive controls. MAIN METHODS: UA was prepared freshly as a suspension in saline solution and administered twice daily, intraperitoneally, at a dose of 250 mg/kg body weight for five weeks to SHR-UA (n=7) and WKY-UA rats (n=5). Controls for both strains were injected with saline solution (WKY-C and SHR-C, n=5 each). Blood pressure, determined by tail-cuff plethysmography, levels of urine and blood biochemical parameters were monitored weekly. Oxidative stress, renal cytokines mRNA levels and immune cells infiltration were determined at the end of the study. KEY FINDINGS: UA did not alter blood pressure in the WKY rats, but markedly prevented the development of hypertension in SHRs. Urine volume was significantly increased in the SHR-UA group. UA protected against renal oxidative stress as indicated by a decrease in MDA content in the SHR-UA group when compared to the SHR-C group; MDA content was unchanged in the WKY animals. Plasma antioxidant capacity decreased significantly in the SHR-UA animals when compared to the other three groups. There was a significant decrease in renal infiltrating lymphocytes in the SHR-UA treated animals. Changes in the expression of TNF-alpha, IL-2 and IL-6 were detected in the SHR-UA group. SIGNIFICANCE: We conclude that UA protects against progression of hypertension in SHR rats.

Effect of uric acid on nephrotoxicity induced by mercuric chloride in rats.

Oxidative stress is an important mechanism in mercury poisoning. We studied the effect of uric acid, a natural and potent reactive oxygen species and peroxynitrite scavenger, in HgCl( 2)-induced nephrotoxicity. Rats were injected with a unique dose of HgCl(2) (2.5 mg/kg body weight, subcutaneously) and then vehicle (for 3 days, twice daily) or HgCl(2) (unique dose) and intraperitoneal uric acid suspension (250 mg/kg body weight, twice daily, for 3 days), and then killed at 24, 48 and 72 hours after HgCl(2) administration (n = 5 for each group). At the end of the experimental study, kidneys and blood samples were taken. Tissues were prepared and examined under light microscopy. Uric acid significantly prevented the increase in plasma levels of creatinine and blood urea nitrogen (BUN); it helped maintain systemic nitrate/nitrite concentration and total antioxidant capacity. Uric acid attenuated the increase of renal lipid peroxidation and it markedly diminished nitrotyrosine signal and histopathological changes as early as 24 hours after HgCl(2) administration. Uric acid did not prevent a decrease in beta-actin signal caused by mercuric chloride, but it promoted a faster recovery when compared to the HgCl(2) alone group. Our results indicate that UA could play a beneficial role against HgCl(2) toxicity by preventing systemic and renal oxidative stress and tissue damage.

Effect of uric acid on gentamicin-induced nephrotoxicity in rats - role of matrix metalloproteinases 2 and 9.

In this work, we aimed to study the effect of uric acid on gentamicin-induced nephrotoxicity. Male Sprague-Dawley rats were assigned to one of six groups (six rats each) which received intraperitoneal injections for 9 days: (S) saline; (UA) Uric acid alone; (G) Gentamicin alone; (G + UA) Gentamicin + uric acid; (G rec) Gentamicin recovery and (G + UA rec) Gentamicin + uric acid recovery. In (G rec) and (G + UA rec), rats recovered for 7 days after the last injection. Urine and blood samples were taken on day 0 and at the end of every stage. Kidneys were harvested for histological scoring, determination of renal malondialdehyde (MDA), zymography and western blots for matrix metalloprotease (MMP)-2 and MMP-9. Uric acid alone did not provoke changes in biochemical and histological parameters when compared to controls. Gentamicin alone increased significantly plasma creatinine and blood urea nitrogen and caused a moderate histological damage. When combined with uric acid, these conditions worsened. MMP-9 activity and expression was decreased in rats from group G + UA as compared with rats from group G, while activity of MMP-2 was similarly increased in both groups when compared to controls. The increase in renal MDA induced by gentamicin was not altered when it was combined with uric acid. During the recovery stage, all biochemical parameters returned to normal levels, though a trend for delay of tubular damage recovery was observed in group G + UA rec when compared with group G rec. The results indicate that uric acid worsens gentamicin-induced nephrotoxicity. The mechanism is likely to implicate down-regulation of MMP-9.

Experimental induction of salt-sensitive hypertension is associated with lymphocyte proliferative response to HSP70.

Renal tubulointerstitial inflammation is a constant feature of experimental models of hypertension and likely plays a role in the pathogenesis of salt-sensitive hypertension. We have previously raised the possibility that the immune cell infiltration is driven by a low grade autoimmune reactivity directed to or facilitated by renal heat shock protein over expression. The present studies were done to gain insight on possible cell-mediated immune mechanisms in experimental hypertension by determining the renal expression of HSP70 and the proliferation index of T lymphocytes cultured with HSP70. We studied male Sprague-Dawley rats with inhibition of nitric oxide (NO) synthase (n=6), protein overload (PO) proteinuria (n=7) and short-term angiotensin II (Ang II) infusion (n=5), and their corresponding control groups. Each model was associated with 2 to 4 fold increase (P<0.05-0.001) in renal HSP70 expression. T cells isolated from the spleens demonstrated a significant two- to nine-fold response compared to controls (P<0.05 or lower for each comparison) when cultured with HSP70. These studies suggest that autoimmunity to stress proteins is involved in the sustained low-grade inflammatory infiltration that occurs in the tubulointerstitial areas of the hypertensive kidney.

Transient improvement of hypertension-induced chronic renal failure with mycophenolate mofetil treatment.

A young female with essential hypertension developed progressive azotemia; renal biopsy showed hypertensive nephrosclerosis with considerable tubulointerstitial disease and cellular infiltration. The addition of mycophenolate mofetil (MMF) to her antihypertensive treatment resulted in a dramatic improvement of renal function during the following three months. When the patient discontinued MMF treatment, end-stage renal failure rapidly developed. This patient represents the first report of the beneficial use of MMF in non-immune chronic renal disease and demonstrates that significant functional improvement may be obtained with the addition of MMF to the treatment of hypertensive nephrosclerosis for patients in whom there is significant tubulointerstitial inflammatory infiltration.

Temporary discontinuation of immunosuppressive treatment and renal graft rejection. Experience of a center in Venezuela.

In some Latin American countries, discontinuation of treatment when immunosuppressive drugs are unavailable can cause late renal graft loss. This retrospective study reports the frequency and consequences of interrupted treatment at a single center in Venezuela. In 2005 and 2006, we evaluated the medical records of and interviewed 303 patients (181 males) followed for more than one year after renal transplantation done between 1973 and 2005. Noncompliance for>1 week was reported by 124 patients; 107 (86.3%) instances were due to unavailability of immunosuppressive drugs at the institution (institutional noncompliance), and the remainder were due to voluntary noncompliance. Acute rejection episodes were about three times as frequent among voluntary noncompliers as institutional noncompliers, probably because voluntary noncompliance lasted longer (mean 42.7+/-standard deviation of 14.1 days) than institutional noncompliance (18.5+/-11.2 days, P<0.001). Graft loss occurred in 63.6% (7/11) of the episodes of voluntary noncompliance and in 33.3% (10/30) of the episodes of institutional noncompliance. Institutional noncompliance represents a preventable cause of graft loss in some transplantation programs in developing countries.

Reduction of renal immune cell infiltration results in blood pressure control in genetically hypertensive rats.

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.