Anatomical and physiological diagnostic discrepancies in fetuses with single-ventricle congenital heart disease in a contemporary cohort.

OBJECTIVE: Image quality of fetal echocardiography (FE) has improved in the recent era, but few recent studies have reported the accuracy of FE, specifically in single ventricle (SV) congenital heart disease (CHD). This study aimed to assess the ability of FE to correctly predict SV-CHD postnatal anatomy and physiology in a contemporary cohort. METHODS: The contemporary clinical reports of patients with SV-CHD, in which FE was performed between July 2017 and July 2021, were compared with postnatal echocardiograms from a formal quality assurance program. SV fetuses were grouped by anatomical subtype. Diagnostic errors were designated as major if the error would have caused significant alteration in parental counseling or postnatal management. The remaining errors were classified as minor. Physiological discrepancies, including prostaglandin-E (PGE) dependency, atrioventricular valve regurgitation (AVVR), pulmonary venous obstruction and restrictive atrial septum (RAS), were assessed by chart review of the postnatal course. RESULTS: A total of 119 subjects were analyzed. SV subtypes in the cohort included hypoplastic left heart syndrome (HLHS) (n = 68), tricuspid atresia (n = 16), double-inlet left ventricle (n = 12), unbalanced atrioventricular canal (UAVC) (n = 11), heterotaxy (n = 9) and other (n = 3). The rate of major anatomical and physiological errors was low (n = 6 (5.0%)). A higher proportion of minor errors was noted in HLHS and tricuspid atresia, but the differences were not statistically significant. Physiological discrepancies were uncommon, with three major discrepancies, including underestimation of the degree of venous obstruction in one non-HLHS fetus with total anomalous pulmonary venous return, overestimation of RAS in one HLHS fetus and incorrect prediction of PGE dependency in one case false-negative for pulmonary blood flow. No discrepancy in degree of AVVR or RAS affected postnatal care. Minor physiological discrepancies included two false-positive predictions of PGE dependency with one false-positive for ductal-dependent systemic flow and one false-positive for pulmonary blood flow. CONCLUSIONS: In this contemporary review of FE at our center, there was high accuracy in describing anatomical and physiological findings in SV-CHD. Major physiological discrepancies were uncommon but included important cases of false-negative prediction of PGE dependency and underestimation of obstruction of total anomalous pulmonary venous return. These data can inform more accurate counseling of families with SV-CHD fetuses and guide diagnostic improvement efforts. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Early manifestations and spectrum of recipient twin cardiomyopathy in twin-twin transfusion syndrome: relation to Quintero stage.

OBJECTIVES: To examine cardiac structural and functional changes in twin-twin transfusion syndrome (TTTS), relative to Quintero stage, as a means of evaluating the spectrum of cardiomyopathy in TTTS. METHODS: This was a cross-sectional, retrospective study of 42 consecutive cases of TTTS referred to a single fetal therapy center. Quintero stages were assigned by standard criteria. Presence of ventricular hypertrophy, cardiomegaly, atrioventricular valve regurgitation (AVVR), ventricular systolic dysfunction and right ventricular outflow tract obstruction on fetal echocardiography were noted. The Doppler myocardial performance index (MPI), an index of global ventricular function, was calculated for both ventricles in subjects with adequate Doppler data. We compared cardiac changes across Quintero stages. RESULTS: There was no cardiomyopathy observed in donor twins. The majority of subjects presented at Quintero Stage I (n = 14), II (n = 14) or III (n = 11), with fewer at Stages IV (n = 2) or V (n = 1). As early as Quintero Stages I and II, a significant proportion of recipient twins had ventricular hypertrophy (17/28, 61%), AVVR (6/28, 21%) or quantitative abnormalities in either right (12/24, 50%) or left (14/24, 58%) ventricular function. Increasing prevalence of biventricular systolic dysfunction and cardiomegaly accompanied advancing Quintero stage. CONCLUSIONS: Changes in cardiac structure and function not reflected in Quintero staging occur in recipient twins early in the evolution of TTTS. Incorporation of cardiac findings into assessment of TTTS severity may prove useful in stratification of risk and treatment selection.

Renin-stimulated TGF-beta1 expression is regulated by a mitogen-activated protein kinase in mesangial cells.

Recent evidence indicates that renin itself might be profibrotic, independent of angiotensin II; however, the signaling system by which renin exerts a direct effect is not known. We tested the hypothesis that renin receptor activation, in turn, activates the extracellular-signal regulated kinase 1 and 2 (ERK1/2) of the mitogen-activated protein kinase system in mesangial cells. Recombinant rat renin induced a rapid phosphorylation of ERK1/2 and subsequent cell proliferation in a dose- and time-dependent manner. ERK1/2 activation by renin addition was not altered by angiotensin-converting enzyme inhibition or angiotensin receptor blockade. An ERK kinase inhibitor significantly reduced the renin-induced ERK1/2 phosphorylation and the subsequent increase in transforming growth factor-beta1 (TGF-beta1) and plasminogen activator inhibitor-1 mRNA expression. A small-inhibiting RNA, siRNA, against the renin receptor completely blocked ERK1/2 activation by rat renin. We conclude that renin induces ERK1/2 activation though a receptor-mediated, angiotensin II-independent mechanism in mesangial cells. This renin-activated pathway triggers cell proliferation along with TGF-beta1 and plasminogen activator inhibitor-1 gene expression. This system may play an important role in the overall profibrotic actions of renin.

Noninhibitory PAI-1 enhances plasmin-mediated matrix degradation both in vitro and in experimental nephritis.

Plasminogen activator inhibitor-type 1 (PAI-1) is thought to be profibrotic by inhibiting plasmin generation, thereby decreasing turnover of pathological extracellular matrix (ECM). A mutant, noninhibitory PAI-1 (PAI-1R) was recently shown by us to increase glomerular plasmin generation and reduce disease in anti-thy-1 nephritis. Here, in vitro and in vivo studies were performed to determine whether enhanced plasmin-dependent ECM degradation underlies the therapeutic effect of PAI-1R. 3H-labeled ECM was produced by rat mesangial cells (MCs). The effect of wild-type PAI-1 (wt-PAI-1) and PAI-1R on ECM degradation by newly plated MCs was measured by the release of 3H into medium. In vivo, anti-thy-1 nephritis was assessed in normal, untreated diseased and PAI-1R treated rats with or without the plasmin/plasminogen inhibitor, tranexamic acid (TA). wt-PAI-1 totally inhibited plasmin generation and reduced ECM degradation by 76% when exogenous plasminogen was added. Although PAI-1R alone had no effect, PAI-1R in the presence of wt-PAI-1 reversed the wt-PAI-1 inhibition of ECM degradation in a time- and dose-dependent manner (P<0.001). Plasmin activity and zymography were consistent with ECM degradation. Plasmin inhibitors: alpha2-antiplasmin, aprotinin, and TA completely blocked PAI-1R's ability to normalize ECM degradation (P<0.001). Consistent with the in vitro results, TA reversed PAI-1R-induced reductions in glomerular fibrin and ECM accumulation. Other measures of disease severity were either unaltered or partially reversed. PAI-1R reduces pathological ECM accumulation, in large part through effectively competing with native PAI-1 thereby restoring plasmin generation and increasing plasmin-dependent degradation of matrix components.

Accuracy of fetal echocardiography: a cardiac segment-specific analysis.

OBJECTIVE: In patients with congenital heart disease, comprehensive, segment-specific analysis of cardiac anatomy has become 'the standard of care', largely as a result of improvements in cardiac imaging technology. Our aim was to apply segment-specific standards to assess the accuracy of fetal echocardiography. METHODS: This was a retrospective review of all fetal echocardiograms (n = 915) performed at our center between August 1998 and June 2003. Of these, 100 studies had congenital heart disease findings and corresponding postnatal studies on the same patients for comparison. An expert independent pediatric echocardiologist, using the standards of accuracy expected of postnatal echocardiography, assessed the studies for the following cardiac segments: abdominal situs, systemic venous return (VR), pulmonary VR, atria, atrioventricular valves, ventricular septum, ventricular hypoplasia, ventricular morphology, semilunar valves, great arterial relation and aortic arch. Sensitivity, specificity, and positive and negative predictive values were calculated for each segment. RESULTS: Specificity and negative predictive value were high for all cardiac segments (range, 82-100%). Sensitivity and positive predictive value were similarly high (range, 83-100%) for most cardiac segments, but were only 50-88% for systemic VR, pulmonary VR and aortic arch segments. CONCLUSIONS: Fetal echocardiography has excellent diagnostic accuracy in describing intracardiac anatomy. However, despite both technological advances and improved physician awareness, assessment of systemic VR, pulmonary VR, and aortic arch anatomy remain challenging.

Perspectives on blockade of TGFbeta overexpression.

Many approaches to blocking profibrotic TGFbeta overexpression are under way. Therapeutic targeting of TGFbeta-Smad signaling holds promise for slowing or halting progressive renal disease. In this issue, Fukasawa et al., using the unilateral ureteral obstruction model, provide a new target for therapeutic intervention by identifying loss of the Smad corepressors Ski and SnoN as a mechanism that amplifies the profibrotic actions of TGFbeta.

Renin increases mesangial cell transforming growth factor-beta1 and matrix proteins through receptor-mediated, angiotensin II-independent mechanisms.

Recent evidence suggesting a strong interplay between components of the renin-angiotensin system and key mediators of fibrosis led us to hypothesize that renin, independent of its enzymatic action to enhance angiotensin (Ang) II synthesis, directly increases production of the fibrogenic cytokine transforming growth factor (TGF)-beta. Human or rat mesangial cells (MCs) were treated with human recombinant renin (HrRenin) or rat recombinant renin (RrRenin) and the effects on TGF-beta1, plasminogen activator inhibitor-type 1 (PAI-1), fibronectin (FN) and collagen 1 mRNA and protein were investigated. Blockade of the rat MC renin receptor was achieved using siRNA. HrRenin or RrRenin, at doses shown to be physiologically relevant, induced marked dose- and time-dependent increases in TGF-beta1. These effects were not altered by adding an inhibitor of renin's enzymatic action (RO 42-5892), the Ang II receptor antagonist losartan or the Ang-converting enzyme inhibitor enalapril. RrRenin also induced PAI-1, FN and collagen 1 mRNA and PAI-1 and FN protein in a dose-dependent manner. Neutralizing antibodies to TGF-beta partially blocked these effects. Supernatant and cell lysate Ang I and Ang II levels were extremely low. MC angiotensinogen mRNA was undetectable both with and without added renin. Targeting of the rat renin receptor mRNA with siRNA blocked induction of TGF-beta1. We conclude that renin upregulates MC TGF-beta1 through a receptor-mediated mechanism, independent of Ang II generation or action. Renin-induced increases in TGF-beta1 in turn stimulate increases in PAI-1, FN and collagen I. Thus, renin may contribute to renal fibrotic disease, particularly when therapeutic Ang II blockade elevates plasma renin.

Maximizing hemodynamic-independent effects of angiotensin II antagonists in fibrotic diseases.

Better understanding of the hemodynamic-independent actions of the renin-angiotensin system (RAS) may lead to improved therapies for heart, kidney, and liver fibrosis. The conventional view of the RAS is that its role is solely hemodynamic. Pharmacologic blockade of the RAS is beneficial in treating hypertension, as well as primary renal and cardiac diseases. Recent findings from clinical trials and several laboratories that used different experimental approaches have revealed a whole new dimension to the RAS that is beyond the realm of hemodynamics. The RAS is best viewed as part of a system of interconnected molecules biologically designed to be activated after tissue injury to promote tissue repair and, when in excess, tissue fibrosis. This new understanding of the RAS has important clinical implications. It predicts and explains why blockade of the RAS with angiotensin-converting enzyme inhibitors (ACEI), the newer receptor antagonists, or both together, will significantly slow the progression of fibrotic disease. However, it further suggests that higher doses and/or a combination of angiotensin II blockade with another agent or agents might truly halt progressive fibrosis.

t-PA promotes glomerular plasmin generation and matrix degradation in experimental glomerulonephritis.

BACKGROUND: In addition to its well-known role in degrading fibrin, recent evidence suggests that plasmin degrades matrix proteins and activates prometalloproteinases. Plasmin is generated from plasminogen by tissue plasminogen activator (t-PA). We hypothesized that t-PA treatment increases plasmin generation in nephritic glomeruli and degrades pathological matrix leading to a therapeutic reduction in matrix accumulation. METHODS: Anti-Thy-1 nephritis was induced by injection of OX-7 antibody. Rats were given twice daily intravenous injections of saline (disease control group) or human recombinant t-PA (rt-PA; 1 mg/kg body weight) on days 3 through 5. Proteinuria, glomerular matrix protein staining, and glomerular mRNA levels for transforming growth factor-beta 1 (TGF-beta 1), fibronectin, and plasminogen activator inhibitor type 1 (PAI-1) were evaluated at day 6. Localization of rt-PA, plasmin generation by glomeruli in vitro, and glomerular production and content of active TGF-beta1 were also investigated. RESULTS: Compared with disease control animals, proteinuria and staining score for periodic acid-Schiff (2.75 +/- 0.17 vs. 1.41 +/- 0.09), fibronectin-EDA+ (19 +/- 2 vs. 14 +/- 1), laminin (35 +/- 2 vs. 25 +/- 2), type I collagen (33 +/- 1 vs. 21 +/- 3), and type IV collagen (27 +/- 2 vs. 23 +/- 1) were significantly reduced in treated rats (P < 0.01). Glomerular TGF-beta 1, fibronectin, and PAI-1 mRNA levels were unchanged. rt-PA colocalized with fibrin along glomerular capillary walls and in the mesangium. Nephritic glomeruli in vitro had decreased plasmin activity, which was elevated by an in vivo presacrifice injection of rt-PA. Glomerular production and content of active TGF-beta 1 were unchanged by the rt-PA injection. CONCLUSIONS: : These results show that injected rt-PA binds to fibrin in nephritic glomeruli, thus increasing plasmin generation and promoting pathological matrix degradation without activating latent TGF-beta. Agents that increase plasmin generation, such as t-PA, may have potential as antifibrotic therapies.

Angiotensin II blockade and low-protein diet produce additive therapeutic effects in experimental glomerulonephritis.

BACKGROUND: Transforming growth factor-beta (TGF-beta) overexpression plays a key role in the accumulation of extracellular matrix in acute and chronic renal diseases. Recent studies have suggested that the degree of reduction in pathological TGF-beta overexpression can be used as a therapeutic index to evaluate the antifibrotic potential of pharmacological angiotensin II (Ang II) blockade in renal disease. Using this target, we found that treatment with the angiotensin I-converting enzyme inhibitor enalapril or the Ang II type 1 receptor antagonist losartan reduced TGF-beta overexpression more effectively at doses clearly higher than those required to control blood pressure. However, both forms of Ang II blockade were only partially effective in normalizing TGF-beta expression. This study investigated whether a greater antifibrotic, TGF-beta-reducing benefit can be achieved when Ang II blockade is combined with dietary protein restriction. METHODS: Mesangioproliferative glomerulonephritis was induced in male Sprague-Dawley rats on a normal-protein diet. Treatment with a low-protein diet and/or maximally effective doses of enalapril or losartan was started one day after disease induction. On the fifth day, 24-hour urine protein excretion was measured. On the sixth day, cortical kidney tissue was taken for periodic acid-Schiff staining. Isolated glomeruli were used for mRNA extraction or were placed in culture for determination of production of TGF-beta1, the matrix protein fibronectin, and the protease inhibitor plasmin activator inhibitor type 1 (PAI-1) by enzyme-linked immunosorbent assay. RESULTS: Compared with untreated nephritic animals on a normal-protein diet, a single treatment with enalapril, losartan, or low-protein diet significantly reduced glomerular TGF-beta production, albeit to a similar degree of approximately 45%. A moderate, but significant further reduction in pathological TGF-beta expression of a total of 65% for enalapril and 60% for losartan was achieved when these drugs were combined with low-protein feeding. This reduction in TGF-beta overexpression paralleled decreased proteinuria, glomerular matrix accumulation, and overproduction of fibronectin and PAI-1. CONCLUSIONS: Ang II blockade and low-protein diet have additive effects on disease reduction, suggesting that disease progression in humans with chronic renal failure may be slowed more effectively when Ang II blockade and low-protein diet are combined. Since maximal pharmacological Ang II inhibition was used, it is likely that dietary protein restriction further reduces pathological TGF-beta overexpression by mechanisms different from those of enalapril or losartan.

Tandem antifibrotic actions of L-arginine supplementation and low protein diet during the repair phase of experimental glomerulonephritis.

BACKGROUND: Based upon the central role transforming growth factor-beta (TGF-beta) overexpression appears to play in renal fibrotic diseases, we have recently advocated reduction of TGF-beta as a therapeutic target. As part of efforts to determine the strength of this approach, we have undertaken studies to quantitate the effects of currently used and promising therapies in terms of their potential to reduce markers of disease in anti-thymocyte-serum (ATS)-glomerulonephritis in the rat. Here we assess the therapeutic effect of L-arginine supplementation, which has been shown to reduce fibrosis in a number of hypertensive models, given alone or in combination with low protein diet and started 24 hours after disease induction. METHODS: Glomerulonephritis was induced by intravenous injection of OX-7 monoclonal antibody into 200 g Sprague-Dawley rats. Twenty-four hours later animals were placed in groups that were either untreated, treated with 1% L-arginine in drinking water or 6% protein diets or both. On the fifth day of disease 24-hour urine specimens were collected and systemic blood pressure was measured. On the sixth day rats were anesthetized. Kidneys were perfused, tissue was taken for PAS staining and glomeruli were isolated. Aliquots of glomeruli were used for RNA preparation and for culture to determine 72-hour production of TGF-beta, fibronectin and plasminogen activator-type 1 (PAI-1), which were assayed by ELISA on culture supernatants. Measures of nitrate and nitrite (NOx) production included plasma NOx, urinary NOx and glomerular production of NOx in culture. RESULTS: All disease measures except proteinuria and including matrix accumulation, TGF-beta, fibronectin and PAI-1 production and mRNA expression for TGF-beta, fibronectin and PAI-1 were significantly and similarly reduced by about 50% in groups treated with L-arginine or with low protein diet. Proteinuria was reduced in low protein treated but not in L-arginine supplemented rats. Neither systemic blood pressure nor measures of NO synthesis showed differences between groups that could be attributed to L-arginine supplementation. In contrast, disease-related increases in glomerular production of NOx were markedly reduced by low protein. Combined therapy resulted in small, but statistically significant decreases in most measures of disease. CONCLUSIONS: L-arginine supplementation reduces fibrotic disease in ATS-induced glomerulonephritis if started after disease induction. The absence of evidence for increased NO production related to L-arginine supplementation suggests that L-arginine is acting here through different pathways from those demonstrated in hypertensive models of disease. The data support the ideas that TGF-beta reduction is a valid therapeutic target and that quantitation of TGF-beta reduction is a useful approach for comparing antifibrotic drug candidates.

From rats to man: a perspective on dietary L-arginine supplementation in human renal disease.

Experimental studies have shown both therapeutic and detrimental consequences of modifying dietary L-arginine intake in renal diseases which likely reflect the complexity of L-arginine metabolism. L-Arginine intake is semi-essential and provides substrate for a number of L-arginine metabolites involved in renal pathology. Dietary L-arginine restriction has been identified as a key mediator of the beneficial effects of low protein diets on human renal fibrosis. Supplementing dietary L-arginine in renal diseases with increased iNOS expression appears to be detrimental and thus, may be harmful in immune-mediated human kidney disorders. Increasing L-arginine intake is beneficial in experimental models of hypertensive renal disease. Based upon available data, we believe additional questions must be answered experimentally, not only to prevent an adverse outcome in humans, but to enhance our chances of human trials which will result in substantially better amelioration of disease than currently available.

L-Arginine supplementation increases mesangial cell injury and subsequent tissue fibrosis in experimental glomerulonephritis.

BACKGROUND: Mesangial cell lysis in the antithymocyte serum (ATS)-induced model of glomerulonephritis is dependent on the generation of cytotoxic nitric oxide (NO) through transient induction of NO synthase (iNOS). We hypothesized that increased availability of L-arginine (L-Arg) during mesangial cell lysis might provide iNOS with increased substrate leading to increased lysis, and that this increased lysis would be reflected in more severe fibrotic disease at day 6. METHODS: To ensure whole body equilibration with high L-Arg at the time of injury, rats were pretreated with 1% L-Arg in drinking water for one week prior to the administration of ATS. Animals were sacrificed six hours after ATS injection when previous experiments had indicated iNOS induction had occurred and at six days. At six hours, plasma was obtained for L-Arg levels and nitrite/nitrate (NOx) content. Renal tissues were taken for histological evaluation of glomerular cell counts, macrophage infiltration (ED-1), and iNOS expression. Glomeruli were isolated for detection of iNOS mRNA and placed in culture to study the dependence of NO production on L-Arg concentration. In rats sacrificed at six days, L-Arg supplementation was stopped 16 hours after ATS injection. Fibrotic disease was evaluated by urinary protein excretion, histological assessment of glomerular cell number, matrix accumulation, and production of transforming growth factor-beta1 and matrix components fibronectin and plasminogen activator inhibitor type-1 (PAI-1) by isolated glomeruli in culture. RESULTS: At six hours, the glomerular cell number was significantly reduced by ATS injection (P < 0.01) and further significantly (P < 0. 05) reduced by L-Arg feeding [normal control (NC) = 64.2 +/- 1, ATS = 53.4 +/- 0.7, ATS + L-Arg = 50.8 +/- 0.7]. Disease increased macrophage infiltration and iNOS protein and iNOS mRNA levels markedly (P < 0.01), whereas L-Arg feeding did not further increase these variables. Plasma L-Arg levels (nmol/ml) were reduced by disease (NC = 121 +/- 9, ATS = 84 +/- 13, P < 0.01) and elevated by L-Arg feeding (ATS + L-Arg = 166 +/- 12, P < 0.01). Plasma NOx was significantly increased by ATS and further increased by ATS + L-Arg (P < 0.05). Production of NOx by cultured glomeruli showed striking L-Arg concentration dependence in six hours but not in normal glomeruli. In the group sacrificed at day 6, day 2 proteinuria was higher in the ATS + L-Arg group compared with the ATS alone group (P < 0.05). Measures of fibrotic disease at day 6 all showed large increases over control with ATS alone (P < 0.01), and further small, but significant increases when L-Arg was combined with ATS (P < 0.05). CONCLUSIONS: The results indicate that if given during disease induction, L-Arg supplementation can enhance iNOS-dependent tissue injury by providing increased substrate. Although the increase in injury with L-Arg supplementation was small, it led to increased fibrosis at day 6. These data predict that in diseases with repeated iNOS-dependent tissue injury, L-Arg supplementation may produce cumulative increases in tissue fibrosis.

Gene therapy by transforming growth factor-beta receptor-IgG Fc chimera suppressed extracellular matrix accumulation in experimental glomerulonephritis.

BACKGROUND: The evidence that transforming growth factor-beta (TGF-beta) is a key mediator in the pathogenesis of fibrotic diseases is now supported by several lines of investigation. This evidence provides a certain base for targeting TGF-beta as an antifibrotic agent. METHODS: We generated a chimeric cDNA, termed TGF beta RII/Fc, encoding an extracellular domain of the TGF-beta type II receptor fused to the IgG-Fc domain, and tested whether TGF beta RII/Fc could be a novel strategy for treating glomerular diseases. RESULTS: In cultured BNul-7 cells, recombinant TGF beta RII/Fc reversed the antiproliferative response induced by TGF-beta 1. In addition, TGF beta RII/Fc diminished the TGF-beta 1-induced production of EIIIA-positive fibronectin in cultured normal rat kidney cells. We then introduced the chimeric cDNA into the muscle of the nephritic rats by the hemagglutinating virus of Japan liposome-mediated gene transfer method in order to block the TGF-beta activity in nephritic glomeruli through systemic delivery of chimeric molecules. Treatment with TGF beta RII/Fc gene transfection could suppress the glomerular TGF-beta mRNA in nephritic rats with a comparable effect in the reduction of extracellular matrix accumulation. CONCLUSION: TGF beta RII/Fc successfully inhibited the action of TGF-beta in vitro and in vivo, and gene therapy by chimeric TGF beta RII/Fc might be feasible for the therapy of glomerulosclerosis.

Increased levels of transforming growth factor-beta in HIV-associated nephropathy.

BACKGROUND: Human immunodeficiency virus-associated nephropathy (HIVAN) is a renal disease of unknown pathogenesis. Recent evidence suggests that the fibrogenic cytokine transforming growth factor-beta (TGF-beta) might be involved. We hypothesized that overproduction of TGF-beta in the kidney might be involved in the pathogenesis of HIVAN. METHODS: The mRNA and protein expression of TGF-beta isoforms, TGF-beta 1, TGF-beta 2, and TGF beta 3, deposition of matrix proteins induced by TGF-beta, and levels of HIV Tat protein were studied in HIVAN. Controls included normal and diseased kidneys from HIV-positive and -negative patients. The ability of Tat to induce production of TGF-beta and matrix proteins was also studied in human mesangial cells. RESULTS: Normal kidneys, thin basement membrane nephropathy, and minimal change disease were negative for the three TGF-beta isoforms and Tat. In HIVAN, levels of TGF-beta isoforms and Tat were significantly increased, along with the expression of TGF-beta mRNA and deposition of matrix proteins stimulated by TGF-beta. Increased levels of TGF-beta isoforms, but not Tat, were also found in other glomerular diseases characterized by matrix accumulation. HIV infection, in the absence of HIVAN, was not associated with an increase in TGF-beta or Tat expression. Tat stimulated the expression and production of TGF-beta 1 and matrix proteins by human mesangial cells. CONCLUSIONS: Our findings suggest that overproduction of TGF-beta is involved in the pathogenesis of HIVAN.

Targeting TGF-beta overexpression in renal disease: maximizing the antifibrotic action of angiotensin II blockade.

BACKGROUND: Overproduction of transforming growth factor-beta (TGF-beta) is a key mediator of extracellular matrix accumulation in fibrotic diseases. We hypothesized that the degree of reduction of pathological TGF-beta expression can be used as a novel index of the antifibrotic potential of angiotensin II (Ang II) blockade in renal disease. METHODS: One day after induction of Thy 1.1 glomerulonephritis, rats were treated with increasing doses of the Ang I converting enzyme (ACE) inhibitor enalapril and/or the Ang II receptor blocker losartan in the drinking water. Six days after disease induction the therapeutic effect on glomerular TGF-beta overexpression was evaluated. RESULTS: Both enalapril and losartan reduced TGF-beta overproduction in a dose-dependent manner, showing a moderate reduction at doses known to control blood pressure in renal forms of hypertension. A maximal reduction in TGF-beta expression of approximately 45% was seen for both drugs starting at 100 mg/liter enalapril and 500 mg/liter losartan, with no further reduction at doses of enalapril up to 1000 mg/liter or losartan up to 2500 mg/liter. Co-treatment with both drugs was not superior to single therapy. Consistent with our hypothesis that reduction in TGF-beta expression is a valid target, other disease measures, including glomerular matrix accumulation, glomerular production and mRNA expression of the matrix protein fibronectin and the protease inhibitor plasminogen-activator-inhibitor type 1 (PAI-1) closely followed TGF-beta expression. CONCLUSIONS: The data suggest that these therapies act through very similar pathways and that, in order to more effectively treat renal fibrosis, these drugs must be combined with other drugs that act by different mechanisms.