microRNA profiling in duodenal ulcer disease caused by Helicobacter pylori infection in a Western population.

Although the connection of microRNAs (miRNAs) to some diseases is well established, their involvement in chronic infections such as Helicobacter pylori has received less attention. The aim was to compare miRNA expression profiling in patients with duodenal ulcer (DU) due to H. pylori infection with that in infected patients without DU and in uninfected patients. The miRNA expression profile was determined by microarrays in antral mucosal samples from well-characterized dyspeptic patients (n = 46). The most significant set of miRNAs was subsequently analysed in an independent validation group of patients (n = 42). Transcripts for IL8, IL12p40, IL12p35 and IL23p19, the signalling molecules MYD88, GATA6, SOCS2 and STAT6 and H. pylori virulence factors cagA and VacA were analysed. Microarray experiments showed that 17 miRNAs were deregulated in the mucosa of H. pylori-infected patients. No significant differences were observed between normal and DU patients. PCR confirmed the up-regulation of miR-9, miR-146a, miR-155 and miR-650 and the down-regulation of miR-96 and miR-204 in the independent validation set of patients. Importantly, miR-9, miR-96, miR-146a and miR-650 expression was specific to chronic-active gastritis. H. pylori-infected patients showed higher levels of IL8 and IL12p40 mRNAs and lower levels of GATA6 and SOCS2 mRNAs. The antral mucosa of patients with non-active or chronic-active gastritis showed significantly lower levels of GATA6, MYD88, SOCS2 and STAT6 mRNAs compared with patients without gastritis. The down-regulation of these factors was not correlated with the expression of any of the validated miRNAs. The exact role of the miRNA changes observed will require further study.

[Comparison of four different primer sets for detection of Helicobacter pylori in gastric biopsies and oral samples by using real-time PCR]. / Comparaison de quatre paires d'amorces différentes dans la détection d'Helicobacter pylori dans les biopsies gastriques et les prélèvements oraux.

AIMS: The presence of Helicobacter pylori. in the oral cavity remains controversial and the most appropriate method for detection of oral H. pylori has yet to be established. The aim of the present study was to compare four different primer sets on the detection of H. pylori in gastric biopsies and oral samples using real-time PCR. MATERIAL AND METHODS: Gastric biopsy and oral samples were collected from eight patients with gastric symptoms. DNA from clinical samples was extracted and analyzed for the presence of H. pylori by real-time PCR (LightCycler 2.0) using four pairs of primers which targeted 16S rRNA (16S rRNA#295; 16S rRNA#120) or glmM (glmM#294; glmM#722) DNA genes. Three H. pylori strains and three clinical isolates served as reference. The specificities of the four primer pairs were examined for seven oral microorganisms and two Helicobacter non-pylori species. RESULTS: Primer pair 16S rRNA#120 showed an acceptable specificity and a high sensitivity. Primer pairs glmM#294 and glmM#722 demonstrated a high specificity but a low sensitivity and primer pair 16S rRNA#295 demonstrated a poor specificity but acceptable sensitivity. Four H. pylori positive gastric biopsies were demonstrated by culture, histology and real-time PCR with primer pairs 16S rRNA#295 or 16S rRNA#120. No H. pylori was detected in oral samples, either by culture or by real-time PCR. CONCLUSION: Of the four different primer pairs examined, 16S rRNA#120 was the most appropriate to detect H. pylori in clinical samples using real-time PCR.

Conversion from calcineurin inhibitors to sirolimus in kidney transplant patients reduces the urinary transforming growth factor-beta1 concentration.

INTRODUCTION: Chronic allograft dysfunction (CAD) is the main cause of late transplant failure. Although several etiologies have been postulated, toxicity for calcineurin inhibitors (CNIs) is one of the most important causes of CAD, characterized by arteriolar hyalinosis, luminal narrowing, increased glomerulosclerosis, and tubulointerstitial damage. It's known that in transplant patients with CAD, fibrogenic mediators such as transforming growth factor beta (TGF-beta) are increased. Sirolimus is an immunosuppressive agent with a distinct mechanism of action compared with CNI. AIM: This study assessed variations in levels of fibrogenic mediators among CAD patients treated with CNIs, before and after conversion to sirolimus. PATIENTS AND METHODS: We studied twelve renal transplant patients with CAD on CNI treatment. TGF-beta in plasma and urine, endothelin-1, and vascular endothelial growth factor (VEGF) were studied before and 8 months after conversion to sirolimus treatment. RESULTS: TGF-beta urine levels decreased from 24.7 +/- 11.2 to 12.8 +/- 5.1 ng/24 h (P = .049). In plasma, a similar decrease trend was observed (22.2 +/- 32 to 10.3 +/- 3 ng/mL), although it was not significant (P = .079). Endothelin-1 showed a decrease (8.1 +/- 3 to 5.2 +/- 1.1 pmol/L; P = .1) and VEGF in plasma increased from 34.3 +/- 37 to 92.2 +/- 86 pg/mL (P = .051). CONCLUSIONS: Patients undergoing conversion from CNI to sirolimus treatment for CAD presented a significant decrease in TGF-beta urine levels, representing a decreased mediator of the CAD fibrogenic process.

Cigarette smoke concentrate increases 8-epi-PGF2alpha and TGFbeta1 secretion in rat mesangial cells.

Epidemiological studies have shown that cigarette smoke, an oxidant agent, is a risk factor for the development of diabetic nephropathy (DN), in which pathogenesis transforming growth factor beta(1) (TGFbeta(1)) plays a key role. In our experimental model we exposed mesangial cell cultures to cigarette smoke concentrate (CSC) to study the effect of smoking on the pathogenesis of DN. Thus, we analyzed the effect of CSC on TGFbeta(1) and lipid peroxidation (8-epi-PGF(2alpha)) in rat mesangial cells. Furthermore, since the protein kinase C (PKC) pathway appears to be a key factor for the enhanced production of TGFbeta(1), we also analyzed the effect of the selective PKCbeta inhibitor LY379196 on TGFbeta(1) response to CSC. CSC induced an increase of both TGFbeta(1) and 8-epi-PGF(2) compared to basal conditions (5 mM glucose). The CSC-induced increase in TGFbeta(1) secretion was significantly suppressed by LY379196. These data suggest that smoking could increase TGFbeta(1) production, probably due to oxidative stress and PKCbeta activation. This finding supports the concept that smoking is a risk factor for DN development.

The effects of smoking and its cessation on 8-epi-PGF2alpha and transforming growth factor-beta 1 in Type 1 diabetes mellitus.

BACKGROUND: Oxidative stress and transforming growth factor-beta 1 (TGF-beta1) are associated with diabetic complications, and smoking is a risk factor. AIMS: This study aimed (i) to compare urinary 8-epi-PGF2alpha and plasma and urinary TGF-beta1 levels obtained in heavy smokers with Type 1 diabetes with those observed in age-matched non-smoker patients with Type 1 diabetes and controls, and (ii) to investigate the effects of smoking cessation (SC) on the above-mentioned parameters in patients with Type 1 diabetes. METHODS AND RESULTS: Compared with control subjects (n = 12), non-smoker diabetic patients (n = 12) presented higher values of urinary 8-epi-PGF2alpha (74.2 +/- 29.6 vs. 29.6 +/- 11.1 pg/mg urinary creatinine, P = 0.01), plasma TGF-beta1 (7.7 +/- 4.7 vs. 3.6 +/- 1.7 ng/ml, P = 0.001) and urinary TGF-beta1 (15.3 +/- 6.3 vs. 8.1 +/- 4.4 ng/mg urinary creatinine, P = 0.02). Compared with non-smoker diabetic patients, smoker diabetic patients (n = 16) showed higher levels of urinary 8-epi-PGF2alpha (107.8 +/- 40.2 vs. 74.2 +/- 29.6 pg/mg urinary creatinine, P = 0.0001), plasma TGF-beta1 (12.6 +/- 4.9 vs. 7.7 +/- 4.7 ng/ml, P = 0.001) and urinary TGF-beta1 (27.5 +/- 16.0 vs. 15.3 +/- 6.3 ng/mg urinary creatinine, P = 0.01). Smoker patients were included in a smoking cessation programme. In the 10 patients that gave up smoking there was a reduction of urinary 8-epi-PGF2alpha (basal: 110.47 +/- 47.0 vs. week 12: 73.2 +/- 25.6; P < 0.001), plasma TGF-beta1 (basal: 11.2 +/- 5.9 vs. week 12: 4.89 +/- 2.25; P < 0.01) and urinary TGF-beta1 (basal: 18.12 +/- 9.27 vs. week 12: 10.32 +/- 2.0; P < 0.01) levels. CONCLUSIONS: In patients with Type 1 diabetes, smoking increased oxidative stress, evaluated by lipid peroxidation, and TGF-beta1 production. Smoking cessation decreased these parameters, providing additional support to encourage diabetic patients to give up smoking.

[Role of transforming growth factor beta-1 gene polymorphisms in the development of chronic allograft nephropathy in renal transplant recipients]. / Papel de los polimorfismos del gen del transforming growth factor beta 1 en el desarrollo de nefropatía crónica del injerto en pacientes trasplantados renales.

BACKGROUND: Chronic allograft nephropathy (CAN) is the main cause of graft loss after the first year of transplantation, and renal biopsies show a predominance of fibrotic lesions. Human transforming growth factor beta-1 (TGF-beta 1) is the principal profibrogenetic cytokine which has been recently implicated in the development of CAN. Seven TGF-beta 1 gene polymorphisms have been recently described and some of them have been related to the development of several diseases. AIM: To analyse the relationship between TGF-beta 1 gene polymorphisms and the development of CAN in a group of renal transplant patients with a long-term follow-up. METHODS: A restriction enzyme-based method for TGF-beta 1 genotyping was used to detect four TGF-beta 1 gene polymorphisms in codon 10, 25 and 5'-flanking region (-800 and -509 positions). A retrospective case-control study were performed on sixty renal transplant recipients with 8 years of post-transplant, 22 of them with CAN (cases) and 38 with normal graft function (controls). We studied 73 subjects to analyse the distribution of the genotypes in the area. RESULTS: The genotype frequencies were similar in the study and control group. The presence of chronic allograft nephropathy was statistically associated with the combination Pro/Pro10 TT509 polymorphism in the TGF-beta 1 gene, and these patients develop chronic rejection more quickly than the rest of the patients. Chronic allograft nephropathy was also associated with delta age recipient-donor, with older donors being a significant risk factor for chronic nephropathy. The logistic regression analysis confirmed the independent role of TT509 Pro/Pro10 TGF-beta 1 polymorphism with a Odd Ratio of 5.8 (1.14-29.7) in chronic nephropathy being the delta age recipient-donor a confounder factor but not an effect modifier. The rest of the TGF-beta 1 gene polymorphisms and the classic risk factors were not associated with the development of chronic allograft nephropathy. CONCLUSIONS: These data suggest a leading role for TGF-beta 1 gene polymorphisms (TT509 Pro/Pro10) in the development of chronic allograft nephropathy. The identification of this genetic predisposition to chronic allograft rejection could play a decisive role in the prevention of this common pathology.

Papel de los polimorfismos del gen del transforming growth factor beta1 en el desarrollo de nefropatía crónica del injerto en pacientes trasplantados renales / Role of transforming growth factor beta-1 gene polymorphisms in the development of chronic allograft nephropathy in renal transplant recipients

La nefropatía crónica del injerto renal (NCIR) es la principal causa de pérdida del injerto después del primer año post-trasplante y en la biopsia renal encontramos un predominio de las lesiones fibróticas. El transforming growth factor beta-1 (TGF-β1) es la principal citoquina profibrogenética y ha sido implicada en el mecanismo de producción de la NCIR. Se han descrito varios polimorfismos del gen del TGF-β1, algunos de ellos se han relacionado con el desarrollo de enfermedades. El objetivo de este estudio es analizar la posible relación entre estos polimorfismos y el desarrollo de NCIR en un grupo de pacientes trasplantados renales con largo tiempo de seguimiento. Mediante enzimas de restricción identificamos cuatro polimorfismos del gen del TGF-β en el codon 10, 25 y en -800 y -509 (en el promotor). Realizamos un estudio retrospectivo de casos y controles donde se estudiaron 60 pacientes trasplantados renales con 8 años de seguimiento post-trasplante, 22 de ellos con NCIR (casos) y 38 con normofunción (controles), analizamos también población general para el estudio de la distribución genotípica en el área geográfica (grupo control externo, n = 73). Las frecuencias genotípicas fueron similares en el grupo control y de estudio. La presencia de NCIR se asoció de forma significativa con la combinación de los polimorfismos Pro/Pro10 TT-509 del gen del TGF-β1 y estos pacientes además desarrollaron NCIR de forma más precoz que el resto. La NCIR se asoció también con la diferencia de edad entre el receptor y el donante (Δ edad r-d), siendo los donantes mayores que el receptor un factor de riesgo para el desarrollo de NCIR. El análisis mediante regresión logística confirmó el papel independiente del polimorfismo TT509 Pro/Pro10 en la NCIR, con un Odd Ratio de 5,8 (1,14-29,7), siendo la edad Δ r-d un parámetro que no modifica el proceso de formas más determinante que el polimorfismo, pero pudiendo añadir al efecto de éste un carácter más marcado. Estos datos sugieren un papel importante de los polimorfismos del gen del TGF-β1 en el desarrollo de NCIR (TT509Pro/Pro10). La identificación de esta predisposición genética para el desarrollo de NCIR podría jugar un papel decisivo en la prevención de esta frecuente patología

Background: Chronic allograft nephropathy (CAN) is the main cause of graft loss after the first year of transplantation, and renal biopsies show a predominance of fibrotic lesions. Human transforming growth factor beta-1 (TGF-β1) is the principal profibrogenetic cytokine which has been recently implicated in the development of CAN. Seven TGF-β1 gene polymorphisms have been recently described and some of them have been related to the development of several diseases. Aim: to analyse the relationship between TGF-β1 gene polymorphisms and the development of CAN in a group of renal transplant patients with a long-term follow- up. Methods: a restriction enzyme-based method for TGF-β1 genotyping was used to detect four TGF-β1 gene polymorphisms in codon 10, 25 and 5’-flanking region (-800 and -509 positions). A retrospective case-control study were performed on sixty renal transplant recipients with 8 years of post-transplant, 22 of them with CAN (cases) and 38 with normal graft function (controls). We studied 73 subjects to analyse the distribution of the genotypes in the area. Results: the genotype frequencies were similar in the study and control group. The presence of chronic allograft nephropathy was statistically associated with the combination Pro/Pro10 TT509 polymorphism in the TGF-β1 gene, and these patients develop chronic rejection more quickly than the rest of the patients. Chronic allograft nephropathy was also associated with Δ age recipient-donor, with older donors being a significant risk factor for chronic nephropathy. The logistic regression analysis confirmed the independent role of TT509 Pro/Pro10 TGF-β1 polymorphism with a Odd Ratio of 5.8 (1.14-29.7) in chronic nephropathy being the Δ age recipient-donor a confounder fator but not an effect modifier. The rest of the TGF-β1 gene polymorphisms and the classic risk factors were not associated with the development of chronic allograft nephropathy. Conclusions: these data suggest a leading role for TGF-β1 gene polymorphisms (TT509Pro/Pro10) in the development of chronic allograft nephropathy. The identification of this genetic predisposition to chronic allograft rejection could play a decisive role in the prevention of this common pathology

Aplicaciones de la biología molecular en el trasplante renal / Mollecular biology in renal transplantation

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Effect of losartan on TGF-beta1 and urinary albumin excretion in patients with type 2 diabetes mellitus and microalbuminuria.

BACKGROUND: The aim of the present study was to determine the effect of losartan on transforming growth factor-beta1 (TGF-beta1) plasma levels and urinary albumin excretion (UAE) in patients with type 2 diabetes mellitus, mild hypertension and microalbuminuria. METHODS: Fourteen patients (eight males, aged 55+/-6 years) with type 2 diabetes mellitus, mild arterial hypertension and microalbuminuria, participating in an open, uncontrolled, pilot study were included. Patients were treated for 8 weeks with losartan. TGF-beta1 plasma levels, UAE and 24-h blood pressure monitoring were determined at baseline and at 4 and 8 weeks. RESULTS: At 4 and 8 weeks of treatment, a reduction was observed in TGF-beta1 plasma levels (5.5+/-4.5 vs 2.0+/-0.6 and 2.6+/-1.0 ng/ml, P<0.005), UAE (96+/-65 vs 59+/-59 and 64+/-47 microg/min, P<0.01), 24-h systolic blood pressure (136+/-9 vs 129+/-9 and 130+/-10 mmHg, P<0.01) and 24-h diastolic blood pressure (77+/-9 vs 74+/-8 and 74+/-7 mmHg, P<0.03). Stratifying the patients by baseline TGF-beta1, seven had TGF-beta1 plasma values higher than normal controls. At 4 and 8 weeks, they showed a marked reduction in TGF-beta1 values (9.0+/-3.9 to 2.1+/-0.7 and 2.5+/-0.7 ng/ml, P<0.01) and UAE (106+/-83 to 49+/-42 and 38+/-26 microg/min, P<0.05), with good correlation between the percentage reduction of both parameters (r=0.83, P<0.01). The remaining seven patients, with normal baseline TGF-beta1 plasma levels, showed no change in TGF-beta1 plasma levels and UAE after treatment. CONCLUSION: Treatment with losartan decreases TGF-beta1 plasma values and UAE in type 2 diabetes mellitus patients with high baseline TGF-beta1 levels, suggesting that TGF-beta1 may be a marker to detect patients who may particularly benefit from renin-angiotensin system blockade.

[Increased adrenomedullin levels in hypertensive patients on maintenance hemodialysis]. / Niveles elevados de adrenomedulina en pacientes hipertensos en programa de hemodiálisis.

Hypertension is a frequent finding in uremic patients. The pathogenesis of this complication in uremia is complex and not fully elucidated. An imbalance between the vasoconstrictor and vasodilator systems may be involved in its pathogenesis. In this study we have evaluated the state of nitric oxide (NO) and adrenomedullin (ADM) in hemodialyzed patients, especially those with hypertension. We included a group of hypertensive hemodialyzed patients (n = 9) and a group of normotensive control patients (n = 10). We measured plasma renin activity, as well as plasma catecholamines, ADM, and nitrite/nitrate levels in basal conditions before starting the hemodialysis session. Plasma volume, as well as left ventricular ejection fraction were also measured. Hemodialysis patients showed plasma levels of nitrite/nitrates and ADM higher than the reference values in the normal population. We observed no differences in the plasma levels of nitrite/nitrates, but ADM levels were higher in hypertensive (278.2 +/- 15.5 pg/ml) patients than in normotensive patients (225 +/- 9.9 pg/ml) (p < 0.05). When considering all patients together, mean arterial pressure positively correlated with plasma ADM (r = 0.468, p < 0.05). Plasma volume and left ventricular ejection fraction were similar in the two groups of patients. In summary, plasma levels of nitrite/nitrates and ADM are increased in hemodialyzed patients, although only ADM levels were further increased in hypertensive patients. Our results do not suggest that a decreased production in the vasodilator factors evaluated is involved in the pathogenesis of hypertension in uremic patients.

Niveles elevados de adrenomedulina en pacientes hipertensos en programa de hemodiálisis / Increased plasma adrenomedullin levels in patients with end-stage renal disease on maintenance hemodialysis: role of hypertension

Los pacientes urémicos presentan con frecuencia hipertensión arterial cuyo origen es multifactorial y no bien dilucidado. Un disbalance entre la actividad de los sistemas presores y vasodilatadores podría estar implicado en su patogenia. En este trabajo nos hemos propuesto valorar el estado del óxido nítrico (NO) y la adrenomedulina (ADM) en pacientes hemodializados con hipertensión arterial. Estudiamos un grupo de pacientes hemodializados hipertensos (n = 9) y un grupo de pacientes normotensos (n = 10) controles. A estos pacientes se les determinó la actividad renina plasmática (ARP), así como niveles plasmáticos de catecolaminas, ADM, nitritos/nitratos (para estimar la producción de NO) en condiciones basales, antes de iniciar la sesión de hemodiálisis. Los niveles plasmáticos cite catecolaminas y ARP eran similares en ambos grupos de pacientes. Los pacientes hemodializados en conjunto presentaban unos niveles de nitritos/nitratos y de ADM superiores a los valores de referencia en la población general. No se observaron diferencias significativas en los niveles de nitritos/n¡tira tos, pero los niveles de ADM eran superiores en los pacientes hipertensos (278,3 ñ 15,5 pg/ml) respecto a los normotensos (224,9 ñ 9,9 pglml) (p < 0;01). Considerando a todos los pacientes en conjunto observamos una correlación positiva entre niveles adrenomedulina y niveles de presión arterial diastólica (r = 0,51, p < 0,05) y media (r = 0,468, p = 0,05).En conclusión, los niveles de ADM y nitritoslnitratos están elevados en los pacientes en HD, aunque sólo los niveles de ADM eran superiores en los pacientes hipertensos. Nuestros resultados no sugieren que un descenso de la liberación de factores vasodilatadores estén implicados en la HTA del paciente urémico (AU)

Beta-adrenergic receptor density and function in left ventricular hypertrophy in young essential hypertensives.

A sympathetic overactivity has been reported in the early stages of essential hypertension and has been involved in the pathogenesis of left ventricular hypertrophy (LVH) in essential hypertension. The state of beta2-adrenergic receptors as related to the presence of this complication was investigated in a group of 15 essential hypertensive patients and compared to 10 normotensive control subjects. Left ventricular mass index was determined by bidimensional echocardiography. Plasma catecholamine levels were measured by a radioenzymatic assay. beta2-adrenoceptor density was measured in intact lymphocytes by radioligand binding assay, using the hydrophilic ligand CGP 12177. beta2- adrenoceptor function was assessed by measuring intracellular cAMP levels in isoproterenol-stimulated lymphocytes. Left ventricular mass index (P < 0.05), body mass index (P < 0.01), plasma noradrenaline levels (P < 0.05) and beta2-adrenoceptor density (P < 0.05) were higher in hypertensives than in controls. Left ventricular mass index correlated with body mass index both in normotensives and hypertensives, as well as with plasma noradrenaline levels only in normotensives. Left ventricular mass index also showed a positive correlation with mean arterial pressure and an inverse relationship with beta2-adrenoceptor density and response only in hypertensive patients. In conclusion, left ventricular hypertrophy in young essential hypertensives is associated to a reduced beta2-adrenoceptor density and function, probably as a compensating mechanism of the hypertrophied myocardiocyte secondary to the increased sympathetic outflow. Journal of Human Hypertension (2000) 14, 17-21.

Increased plasma adrenomedullin levels in hemodialysis patients with sustained hypotension.

BACKGROUND: Sustained hypotension in end-stage renal disease patients is characterized, despite an overactivation of the sympathetic and renin-angiotensin systems, by decreased vascular resistance and a blunted vascular response to pressor stimuli. An increased production of one or more vasodilator substances might play a role in the reduced vascular resistance and response to pressor stimuli in these patients. We evaluated the possible role of an increased production of nitric oxide and/or adrenomedullin (ADM) in the pathophysiology of chronic hypotension in hemodialysis (HD) patients. METHODS: Three groups of hypotensive (N = 9), normotensive (N = 10), and hypertensive (N = 9) HD patients were included in the study. Plasma renin activity (PRA) and plasma levels of catecholamines, ADM, nitrite/nitrate (an estimator of nitric oxide production), tumor necrosis factor (TNF), and interleukin-1beta (IL-1beta) were measured. Plasma volume and left ventricular ejection fraction (LVEF) were also evaluated. RESULTS: Plasma levels of nitrite/nitrate and ADM were elevated in HD patients with respect to the reference values in normal subjects. Plasma ADM levels, but not nitrite/nitrate levels, were higher in hypotensive (368.1 +/- 25.4 pg/mL) than normotensive (225 +/- 9.9 pg/mL) and hypertensive HD patients (278.2 +/- 15.5 pg/mL, P < 0.01). When considering hypotensive and normotensive patients together, the mean blood pressure inversely correlated with time on HD (r = -0. 53, P < 0.05) and plasma ADM levels (r = -0.78, P < 0.01). CONCLUSIONS: Plasma ADM and nitrite/nitrate levels are increased in HD patients, but only ADM levels were higher in hypotensive than in normotensive and hypertensive HD patients. The higher plasma levels of this peptide in hypotensive patients and its inverse correlation with mean arterial pressure suggest that ADM may be involved in the pathophysiology of chronic hypotension in HD patients.

Losartan decreases plasma levels of TGF-beta1 in transplant patients with chronic allograft nephropathy.

BACKGROUND: Chronic allograft nephropathy represents the principal cause of graft loss after the first year of transplantation. Transforming growth factor-beta1 (TGF-beta1) is a key factor in fibrogenesis and has been involved in the pathogenesis of chronic allograft nephropathy and other chronic nephropathies. Experimental studies have demonstrated that the angiotensin II receptor antagonist (losartan) could decrease the synthesis of TGF-beta1. The aim of this study was to determine the plasma levels of TGF-beta1 in transplant patients with chronic allograft nephropathy, and to evaluate the effect of losartan on TGF-beta1 plasma levels and other vasoactive peptides (angiotensin II, plasma renin activity, aldosterone, endothelin-1, and nitrites and nitrates). Angiotensin-converting enzyme genotypes were also determined in all patients. METHODS: Fourteen transplant patients with chronic allograft nephropathy were included. Treatment with losartan (50 mg) was introduced. Consecutive determinations of TGF-beta1 and other vasoactive peptides were performed during follow-up. RESULTS: Patients with chronic allograft nephropathy presented higher plasma levels of TGF-beta1 than the control groups. The treatment with losartan significantly decreased the plasma levels of TGF-beta1 (P < 0.05) and endothelin (P < 0.05) in all patients. The decrease of TGF-beta1 was statistically correlated with the blockade of the angiotensin II receptor (P < 0.05). No significant correlation could be demonstrated between angiotensin-converting enzyme genotypes and TGF-beta, endothelin-1, and nitrite-nitrate serum levels. CONCLUSIONS: This study demonstrates that losartan significantly decreases the plasma levels of TGF-beta1, the most important fibrogenetic factor. These results could play a decisive role in the treatment and prevention of chronic nephropathies, not only graft nephropathy, because the intrinsic pathogenetic mechanism is very similar in all forms, with a crucial roles for the renal renin-angiotensin system and TGF-beta1.

Contraction of human hepatic stellate cells activated in culture: a role for voltage-operated calcium channels.

BACKGROUND/AIMS: Voltage-operated calcium channels are essential for the regulation of vascular tone and are potential targets for vasodilating agents. They regulate calcium entry and thereby cell contraction in vascular cell types. Hepatic stellate cells in the activated phenotype have contractile properties and could participate in the regulation of sinusoidal blood flow. Thus, this study was aimed at investigating the presence of voltage-operated calcium channels in human hepatic stellate cells activated in culture and the effects of their stimulation on intracellular calcium concentration ([Ca2+]i) and cell contractility. METHODS: Binding studies using [3H]-nitrendipine were performed to demonstrate the presence of voltage-operated calcium channels. Voltage-operated calcium channels were stimulated by causing cell membrane depolarization either by electrical field stimulation or extracellular high potassium. [Ca2+]i and cell contraction were measured in individual cells loaded with fura-2 using a morphometric method with an epifluorescence microscope coupled to a charge-coupled device-imaging system. RESULTS: Binding studies demonstrated the existence of voltage-operated calcium channels in human activated hepatic stellate cells (7.1+/-1.4x10(4) sites/cell with a Kd of 2.1+/-0.1 nM). Both electrical field stimulation and potassium chloride-induced cell depolarization resulted in a marked and prolonged increase in [Ca2+]i followed by intense cell contraction. The degree of cell contraction correlated with the intensity of calcium peaks. Removal of extracellular calcium or preincubation of cells with nitrendipine, a specific antagonist of voltage-operated calcium channels, completely blocked the effects on [Ca2+]i and cell contraction, whereas preincubation of cells with BayK-8644, a specific agonist of voltage-operated calcium channels, increased calcium peaks and contraction. CONCLUSION: Activated human hepatic stellate cells have a large number of voltage-operated calcium channels, the activation of which is associated with an increase in [Ca2+]i followed by marked cell contraction. Voltage-operated calcium channels probably play an important role in the regulation of activated hepatic stellate cells contractility.