Preemptive plasmapheresis and recurrence of FSGS in high-risk renal transplant recipients

Recurrent focal segmental glomerulosclerosis (FSGS) following transplantation is ascribed to the presence of a circulating FSGS permeability factor (FSPF). Plasmapheresis (PP) can induce remission of proteinuria in recurrent FSGS. This study addressed the efficacy of pre-transplant PP in decreasing the incidence of recurrence in high-risk patients. Ten patients at high-risk for FSGS recurrence because of rapid progression to renal failure (n = 4) or prior transplant recurrence of FSGS (n = 6) underwent a course of 8 PP treatments in the peri-operative period. Recurrences were identified by proteinuria >3 g/day and confirmed by biopsy. Seven patients, including all 4 with first grafts and 3 of 6 with prior recurrence, were free of recurrence at follow-up (238-1258 days). Final serum creatinine in 8 patients with functioning kidneys averaged 1.53 mg/dL. FSGS recurred within 3 months in 3 patients, each of whom had lost prior transplants to recurrent FSGS. Two of these progressed to end-stage renal disease (ESRD) and the third has significant renal dysfunction. Based on inclusion criteria, recurrence rates of 60% were expected if no treatment was given. Therefore, PP may decrease the incidence of recurrent FSGS in high-risk patients. Definitive conclusions regarding optimal management can only be drawn from larger, randomized, controlled studies.

Modulation of cell proliferation and hypertrophy by gangliosides in cultured human glomerular mesangial cells

Glomerular mesangial cells (GMCs) in diverse renal diseases undergo cell proliferation and/or hypertrophy, and gangliosides have been reported to play an important role in modulating cell structure and function. This study compared the effects of transforming growth factor-beta1 (TGF-beta1) and the effects of the application of exogenous gangliosides on GMCs and investigated whether the application of exogenous gangliosides regulated cellular proliferation and hypertrophy. Human GMCs were cultured with exogenous gangliosides and TGF-beta1 in a media containing 10% fetal bovine serum and in a media without the fetal bovine serum. Exogenous gangliosides biphasically changed the proliferation of human GMCs (0.1-1.0 mg/mL). A low concentration (0.1 mg/mL) of gangliosides mainly increased the number of human GMCs, whereas cellular proliferation was significantly reduced by raising the concentration of exogenous gangliosides. TGF-beta1 greatly reduced the number of human GMCs in a concentration-dependent manner (1-10 ng/mL). Serum deprivation accelerated the gangliosides- and TGF-beta1-induced inhibition of mesangial cell proliferation to a greater extent. Gangliosides (1.0 mg/ mL) and TGF-beta1 (10 ng/mL) both caused a significant increase in the incorporation of [3H]leucine per cell in the serum-deprived condition, whereas it was completely reversed in serum-supplemented condition. Similar results to the [3H]leucine incorporation were also observed in the changes in cell size measured by flow cytometric analysis. These results show that exogenous gangliosides modulate cell proliferation and hypertrophy in cultured human GMCs, and these cellular responses were regulated differently based on whether the media contained serum or not. Results from the present study raise new possibilities about the potential involvement of gangliosides in the development of mesangial cell proliferation and hypertrophy.

Podocyte hypertrophy, "adaptation," and "decompensation" associated with glomerular enlargement and glomerulosclerosis in the aging rat: prevention by calorie restriction

Whether podocyte depletion could cause the glomerulosclerosis of aging in Fischer 344 rats at ages 2, 6, 17, and 24 mo was evaluated. Ad libitum-fed rats developed proteinuria and glomerulosclerosis by 24 mo, whereas calorie-restricted rats did not. No evidence of age-associated progressive linear loss of podocytes from glomeruli was found. Rather, ad libitum-fed rats developed glomerular enlargement over time. To accommodate the increased glomerular volume, podocytes principally underwent hypertrophy, whereas other glomerular cells underwent hyperplasia. Stages of hypertrophy through which podocytes pass en route to podocyte loss and glomerulosclerosis were identified: Stage 1, normal podocyte; stage 2, nonstressed podocyte hypertrophy; stage 3, "adaptive" podocyte hypertrophy manifest by changes in synthesis of structural components (e.g., desmin) but maintenance of normal function; stage 4, "decompensated" podocyte hypertrophy relative to total glomerular volume manifest by reduced production of key machinery necessary for normal podocyte function (e.g., Wilms' tumor 1 protein [WT1], transcription factor pod1, nephrin, glomerular epithelial protein 1, podocalyxin, vascular endothelial growth factor, and alpha5 type IV collagen) and associated with widened foot processes and decreased filter efficiency (proteinuria); and stage 5, podocyte numbers decrease in association with focal segmental glomerulosclerosis. In contrast, in calorie-restricted rats, glomerular enlargement was minor, significant podocyte hypertrophy did not occur, podocyte machinery was unchanged, there was no proteinuria, and glomerulosclerosis did not develop. Glomerular enlargement therefore was associated with podocyte hypertrophy rather than hyperplasia. Hypertrophy above a certain threshold was associated with podocyte stress and then failure, culminating in reduced podocyte numbers in sclerotic glomeruli. This process could be prevented by calorie restriction.

Combined therapy of cilazapril and losartan has no additive effects in ameliorating adriamycin-induced glomerulopathy

AIMS

Effects of the blockade of renin-angiotensin system (RAS), by angiotensin-converting enzyme inhibitor (ACEi), type 1 angiotensin II receptor blocker (ARB), or a combination of both, were evaluated in Adriamycin (ADR)-induced glomerulopathy.

METHODS

Male Sprague-Dawley rats (180-250 g) were induced of glomerulopathy by treatment with ADR (2 mg/kg, i.v.). Six weeks later, they were treated with cilazapril (1 mg/kg/day) and/or losartan (10 mg/kg/day) for an additional 6 weeks.

RESULTS

The urinary excretion of protein progressively increased following the treatment with ADR, which was prevented by ACEi, ARB, and a combination of both. Similarly, the glomerulopathy assessed by glomerulosclerosis index was also ameliorated by ACEi or ARB. However, combined therapy of both ACEi and ARB was without an additional effect (Control 1.4 +/- 0.4%, ADR 10.7 +/- 2.7%**, ACEi 0.8 +/- 0.4%, ARB 2.6 +/- 1.0%, ACEi+ARB 1.7 +/- 1.5%, ** p < 0.01 vs. Control). The expression of transforming growth factor-beta(1) was increased following the treatment with ADR (1.4 +/- 0.07-fold, p < 0.05 vs. Control), however, the degree of which was similarly blunted by either ACEi, ARB, or the combination of both. The expression of type 1 angiotensin II receptor mRNA increased following the treatment with ADR, the degree of which was further upregulated by ACEi and decreased by ARB to the control level (ADR 1.3 +/- 0.06-fold*, ACEi 1.8 +/- 0.05-fold***, ARB 1.0 +/- 0.04-fold, * p < 0.05 and *** p < 0.001 vs. Control). The combined therapy of ACEi and ARB still showed an upregulation of type 1 angiotensin II receptor mRNA, however, of which degree was mitigated compared with that induced by ACEi alone (ACEi+ARB 1.5 +/- 0.04-fold, ** p < 0.01 vs. Control). On the contrary, the expression of type 2 angiotensin II receptor mRNA was downregulated following the treatment with ADR, which was similarly restored to the control level by ACEi, ARB, and a combination of both (ADR 0.5 +/- 0.08-fold**, ACEi 1.0 +/- 0.06-fold, ARB 1.0 +/- 0.05-fold, ACEi+ARB 1.0 +/- 0.05-fold, ** p < 0.01 vs. Control).

CONCLUSION

It is suggested that combined therapy of ACEi and ARB with relatively high or maximal doses of each drug has no additive or synergistic benefits on the progression of ADR-induced glomerulopathy. Effects of RAS blockade may in part be related to differential regulation of type 1 and type 2 angiotensin II receptors.

Protective effects of blocking renin-angiotensin system on the progression of renal injury in glomerulosclerosis

To investigate the protective effects of blocking rennin-angiotensin system (RAS) on the progression of renal injury in glomerulosclerosis, a glomerulosclerosis model was made for SD rats by unilateral nephrectomy and being injected with Adriamycin into caudal vein. The rats with glomerulosclerosis were randomly divided as ten per group into those without further treatment (group D) and those treated with Benazepril (group DB), Losartan (group DL), or sham-operation (group C), respectively. After 6 weeks of administration of Benazepril or Losartan, the mRNA expressions of TGF-beta1, Col IV, Fn, ET-1 and iNOS in renal cortex were measured by RT-PCR. Besides, the expressions of TGF-beta1, ET-1 and iNOS at protein level were detected by Western blotting and the concentrations of Col IV and Fn were analyzed with immunohistochemistry respectively. Results showed that the rats in group D appeared as obvious proteinuria, hypoalbuminemia and hypercholesterolemia, which had a significant difference compared with group C (p < 0.05), and most of their mesangiums were detected with cellular proliferation and significant increasing for extracellular matrix. Renal cortex TGF-beta1, Col IV, Fn, ET-1 and iNOS in rats of group D were increased by 3.59, 2.57, 2.21, 2.58 and 3.28 times at mRNA level, and by 2.60, 1.40, 0.75, 1.83 and 2.15 times at protein level, respectively, compared with group C. When the animals were treated with Benazepril (group DB) or Losartan (group DL), however, the biochemical and pathological damages were significantly recovered, and protein expressions of TGF-beta1, Col IV, Fn, ET-1 and iNOS were also significantly diminished (p < 0.05). This study suggested that blocking RAS using Benazepril or Losartan can have protective effects on the renal injury in glomerulosclerosis by down-regulating the expressions of TGF-beta1, Col IV, Fn, ET-1 and iNOS.

Inhibition of Matrix Metalloproteinases During Chronic Allograft Nephropathy in Rats

BACKGROUND

Chronic allograft nephropathy (CAN) belongs to the major causes of long-term kidney allograft failure. One of the histologic hallmarks of CAN is interstitial fibrosis, influenced by matrix metalloproteinases (MMPs) that are controlling extracellular matrix (ECM) degradation. Whether MMPs affect the development and progression of CAN is not clear so far. To analyze the role of MMPs in CAN, we investigated the effects of an early and a late application of BAY 12-9566, an inhibitor of MMP-2, -3, and -9 on the development and progression of CAN in a rat kidney-transplantation model.

METHODS

Fisher kidneys were orthotopically transplanted into Lewis recipients that were treated with BAY 12-9566 (15 mg/kg per day) or vehicle either for the first 10 days after transplantation (early treatment) or from week 12 to week 20 after transplantation (late treatment). Proteinuria was analyzed every 4 weeks up to week 20 after transplantation when kidney grafts were removed for further analysis.

RESULTS

Early MMP-inhibition resulted in a significantly reduced 24-hour protein excretion that was paralleled by a lower grade of CAN after 20 weeks. However, late MMP inhibition starting at week 12 after transplantation resulted in significantly higher proteinuria and a higher grade of CAN as compared with controls. Furthermore, transforming growth factor-beta and platelet-derived growth factor-B chain mRNA levels were significantly increased in these animals.

CONCLUSIONS

Inhibition of MMPs early after transplantation reduced the development and progression of CAN but promoted CAN if initiated at later stages. Thus, MMPs are involved in the development and progression of CAN.

Pharmacological Inhibition and Genetic Deficiency of Plasminogen Activator Inhibitor-1 Attenuates Angiotensin II/Salt-Induced Aortic Remodeling

OBJECTIVE

To test the hypothesis that pharmacological plasminogen activator inhibitor (PAI)-1 inhibition protects against renin-angiotensin-aldosterone system-induced cardiovascular injury, the effect of a novel orally active small-molecule PAI-1 inhibitor, PAI-039, was examined in a mouse model of angiotensin (Ang) II-induced vascular remodeling and cardiac fibrosis.

METHODS AND RESULTS

Uninephrectomized male C57BL/6J mice were randomized to vehicle subcutaneus, Ang II (1 mug/h) subcutaneous, vehicle+PAI-039 (1 mg/g chow), or Ang II+PAI-039 during high-salt intake for 8 weeks. Ang II caused significant medial, adventitial, and aortic wall thickening compared with vehicle. PAI-039 attenuated Ang II-induced aortic remodeling without altering the pressor response to Ang II. Ang II increased heart/body weight ratio and cardiac fibrosis. PAI-039 did not attenuate the effect of Ang II on cardiac hypertrophy and increased fibrosis. The effect of PAI-039 on Ang II/salt-induced aortic remodeling and cardiac fibrosis was comparable to the effect of genetic PAI-1 deficiency. Ang II increased aortic mRNA expression of PAI-1, collagen I, collagen III, fibronectin, osteopontin, monocyte chemoattractant protein-1, and F4/80; PAI-039 significantly decreased the Ang II-induced increase in aortic osteopontin expression at 8 weeks.

CONCLUSIONS

This study demonstrates that pharmacological inhibition of PAI-1 protects against Ang II-induced aortic remodeling. Future studies are needed to determine whether the interactive effect of Ang II/salt and reduced PAI-1 activity on cardiac fibrosis is species-specific. In this study, the effect of pharmacological PAI-1 inhibition in a mouse model of Ang II-induced vascular remodeling and cardiac fibrosis was examined. PAI-1 inhibition significantly attenuated Ang II-induced aortic medial and wall thickening, but not cardiac hypertrophy, and enhanced Ang II/salt-induced cardiac fibrosis.

Olmesartan medoxomil, a newly developed angiotensin II type 1 receptor antagonist, protects against renal damage in advanced glycation end product (age)-injected rats

Diabetic nephropathy is a leading cause of end-stage renal disease in industrialized countries. Although the molecular mechanisms for the development and progression of diabetic nephropathy are not fully understood, the formation of advanced glycation end products (AGEs) and activation of the renin-angiotensin system (RAS) have been considered to be the main factors participating in the pathogenesis of diabetic nephropathy. However, functional cross-talk between AGEs and the RAS remains to be elucidated. In this study, we examined the effects of oral administration of olmesartan medoxomil, a newly developed angiotensin II type 1 receptor antagonist, on renal damage in AGE-treated rats. Administration of olmesartan medoxomil significantly inhibited the increase of systolic and diastolic blood pressure levels and urinary N-acetyl-beta-D-glucosaminidase activity in exogenously AGE-injected rats. Furthermore, olmesartan medoxomil treatment also prevented glomerulosclerosis in AGE-treated rats. These results indicate that exogenous AGE treatment could induce renal damage via the activation of the RAS. Our study suggests that olmesartan medoxomil could be a valuable drug for the treatment of diabetic nephropathy by blocking the deleterious effects of AGEs.

AT-1 receptor blockade prevents proteinuria, renal failure, hyperlipidemia, and glomerulosclerosis in the Imai rat

BACKGROUND

The Imai rat is a model of spontaneous focal glomerulosclerosis which leads to nephrotic syndrome, hyperlipidemia, hypertension, and progressive renal failure. We evaluated the effects of angiotensin II receptor type 1 (AT-1)blockade, and compared the results with the effects of the administration of hypolipidemic treatment with a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor. All treatments were started at 10 weeks of age when the rats were already proteinuric and continued for 6 months when rats were sacrificed.

METHODS

The following groups (N= 6 each) were studied: (1) control Sprague-Dawley rats, 34 weeks old; (2) Imai group that received vehicle; (3) Imai + angiotensin II receptor blockade (ARB) group that received olmesartan (10 mg/kg/day by gastric gavage); (4) Imai + prava group, that received pravastatin (20 mg/kg/day by gastric gavage); and (5) Imai + ARB + prava group that received both ARB and pravastatin. Lipid profile, renal function, and structure were assessed at 6 months.

RESULTS

As expected, the untreated Imai rats exhibited heavy proteinuria, hypoalbuminemia, hypertension, renal insufficiency, marked glomerulosclerosis, tubulointerstitial inflammation, and profound hyperlipidemia. Pravastatin treatment alone led to a significant, but partial improvement of hyperlipidemia and renal disease. The ARB treatment alone or in combination with pravastatin resulted in normalization of the blood pressure, urinary protein excretion, plasma cholesterol, triglycerides, low-density lipoproteins (LDLs), very low-density lipoproteins (VLDLs), and albumin concentrations and renal function. Significant glomerulosclerosis was prevented and tubulointerstitial injury and immune cell infiltration were reduced by long-term AT-1 blockade.

CONCLUSION

The study revealed that long-term AT-1 blockade corrects proteinuria, hyperlipidemia, and nephropathy in this model of spontaneous glomerulosclerosis.

Tranilast attenuates structural and functional aspects of renal injury in the remnant kidney model

Pathologic fibrosis is a key feature of progressive renal disease that correlates closely with kidney dysfunction and in which the prosclerotic growth factor TGF-beta has been consistently implicated. Tranilast (n-[3,4-dimethoxycinnamoyl] anthranilic acid), an antifibrotic agent that is used to treat hypertrophic scars and scleroderma, has also been shown to inhibit TGF-beta-induced extracellular matrix synthesis in a range of cell types, including those of renal origin. Therefore, the effects of tranilast on kidney fibrosis and dysfunction were examined in the subtotal nephrectomy model of progressive renal injury. Subtotal nephrectomy led to proteinuria and renal dysfunction in association with glomerulosclerosis, tubulointerstitial fibrosis, and macrophage accumulation. Despite persistent hypertension, treatment with tranilast led to a reduction in albuminuria (61.7 (x)/(/) 1.2 versus 20.5 (x)/(/) 1.3 mg/d; P < 0.01) and plasma creatinine (0.16 versus 0.08 mmol/L; P < 0.01) in subtotally nephrectomized rats. In addition, features suggestive of TGF-beta activation, including glomerulosclerosis, tubulointerstitial fibrosis, tubular atrophy, and macrophage accumulation, all were significantly attenuated by tranilast in association with evidence of reduced TGF-beta signaling in vivo. In the context of a recent pilot study in humans, the findings of the present report suggest that tranilast may provide a novel strategy for the treatment of progressive kidney disease characterized by fibrotic scarring.

Combination Therapy with Angiotensin-Converting Enzyme Inhibitor and Oral Adsorbent of Uremic Toxins Can Delay the Appearance of Glomerular Sclerosis and Interstitial Fibrosis in Established Renal Failure

BACKGROUND/AIM

Angiotensin II plays a central role in the progression of chronic renal failure (CRF), and administration of angiotensin-converting enzyme inhibitor (ACEI) in rats delays the progression of CRF. However, ACEI has little effect on CRF progression in rats with established CRF. We therefore examined whether combination therapy with ACEI and oral adsorbent for uremic toxins in the gastrointestinal tract has the desired effect.

METHODS

Rats subjected to subtotal nephrectomy were given enalapril at 20 mg/kg (n = 10, group E), AST-120 at 5 g (n = 10, group A), enalapril and AST-120 together at the same doses (n = 10, group EA), or no treatment (n = 10, group C) 8 weeks after the operation. The substances were administered in 100 g rat chow. All animals were pair-fed, and all were killed after 8 weeks of pair-feeding.

RESULTS

Body weight did not differ between groups during the study. Blood pressure at week 8 was significantly lower in groups E and EA than in groups C and A (p < 0.05). Urinary protein excretion level and renal plasma flow rate at week 8 were significantly less in groups E and EA than in group C (p < 0.05, p < 0.01). The glomerular filtration rate at week 8 was significantly higher in group EA than in group C (p < 0.05). The glomerular sclerosis index and interstitial fibrosis area at week 8 were significantly less in group EA than in group C (p < 0.01).

CONCLUSION

ACEI and AST-120 in combination can delay progression of established CRF in rats by inhibiting the appearance of glomerular sclerosis and interstitial fibrosis.

Reversal of collapsing glomerulopathy in mice with the cyclin-dependent kinase inhibitor CYC202

Collapsing glomerulopathy (CG) has become an important cause of end-stage renal disease. Whether associated with HIV-1 or other potential etiologies, the pathogenesis of CG converges to induce aberrant proliferation of renal epithelium along the entire nephron. This raises the possibility that targeting cell-cycle progression may be an effective therapeutic strategy for CG. Here, we ask whether the cyclin-dependent kinase (CDK) inhibitor, CYC202 (R-roscovitine), could attenuate or reverse existing renal disease in Tg26 mice, a well characterized HIV-1 transgenic mouse model of CG. Tg26 mice were age and disease matched through analysis of urine (protein/creatinine) to generate 12 treatment pairs covering a range of mild to severe CG. One mouse from each pair received either vehicle or 75 mg/kg of CYC202 every 12 h for 20 d, a dose 20% above that needed to prevent the development of CG. After treatment, urinary, serologic, and histopathologic indices of nephrosis showed reversal of CG in 8 of 12 CYC202-treated mice compared with progression of CG in 10 of 12 vehicle-treated mice, demonstrating a significant therapeutic benefit from CYC202 (P < 0.05). Pharmacokinetic profiles showed that concentrations of CYC202 known to inhibit cell-cycle and transcriptional CDK in vitro were achieved in plasma at efficacious doses. However, amelioration of CG by CYC202 did not correlate with decreases in kidney HIV-1 transgene expression, indicating that suppression of HIV-1 transcription was not a prerequisite for the antiproliferative activity of CYC202. These results demonstrate a novel therapeutic strategy for CG.

Prevention of renal vascular and glomerular fibrosis by epidermal growth factor receptor inhibition

Hypertension is frequently associated with the development of renal vascular and glomerular fibrosis. The purpose of the present study was to investigate whether epidermal growth factor receptor (EGFR) activation participates in the development of renal fibrosis and to test if blockade of EGFR activation would have therapeutic effects. Experiments were performed during nitric oxide (NO) deficiency-induced hypertension in rats (L-NAME model). After 4 weeks of L-NAME treatment, animals developed hypertension associated to deterioration of renal structure and function. Over the same period, EGFR was activated twofold within glomeruli. This activation was accompanied by increased activity of the mitogen-activated protein kinase (MAPK) p42/p44 pathway and exaggerated collagen I expression. Gefitinib, an EGFR-tyrosine kinase inhibitor, given concomitantly with L-NAME, normalized MAPK activation and collagen I expression and prevented the decline of renal function and the development of fibrosis. Since endothelin mediates the L-NAME-induced fibrogenesis, the endothelin-EGFR interaction was tested in transgenic mice expressing luciferase under the control of collagen I-alpha2 promoter: In renal cortex of these animals, the endothelin-induced collagen I gene activity was inhibited by an EGFR-phosphorylation inhibitor. These results provide the first evidence that EGFR activation plays an important role in the progression of renal vascular and glomerular fibrosis.

Renal damage is not improved by blockade of endothelin receptors in primary renin-dependent hypertension

OBJECTIVE

Secondary activation of the renin-angiotensin system plays a major role in the progression of chronic nephropathies, and blockade of endothelin (ET) receptors has been shown to confer nephroprotection in experimental models of proteinuric renal disease. We tested the nephroprotective potential of selective endothelin A receptor (ETA) and non-selective ETA and endothelin B (ETA/B) receptor blockade in the TGR(mRen2)27 transgenic rat model with renin-dependent hypertension (Ren2).

DESIGN

Ren2 animals were treated between 10 and 30 weeks of age with the selective ETA receptor antagonist darusentan (Ren2-ETA) and the ETA/B receptor antagonist Lu420627 (Ren2-ETA/B), and compared with transgene negative Sprague-Dawley (SD) controls. Since the elevated systolic blood pressure in Ren2 was not affected in either Ren2-ETA or Ren2-ETA/ETB, an additional Ren-2 group was treated with a non-antihypertensive dose of the angiotensin II type 1 receptor blocker eprosartan (Ren2-AT1).

RESULTS

During the 20-week observation period 35% of untreated Ren2, 30% of Ren2-ETA/B, 50% of Ren2-ETA, and 83% of Ren2-AT1 animals survived compared with 100% of SD rats. Renal endothelin-1 mRNA expression and proteinuria (4.1-fold) were significantly elevated in Ren2 compared with SD rats (P < 0.05, respectively). Proteinuria was normalized to SD control levels in Ren2-AT1 (P < 0.05) but increased further in Ren2-ETA (7.7-fold) and Ren2-ETA/B (15-fold) (P < 0.05, respectively). Glomerulosclerosis, tubulointerstitial damage and renal osteopontin mRNA expression were reduced in Ren2-AT1 (P < 0.05, respectively) but remained unchanged or increased further in Ren2-ETA and Ren2-ETA/B compared with Ren2.

CONCLUSION

ET receptor blockade fails to improve renal damage and mortality in primary renin-dependent hypertension.

Nephrotic syndrome after conversion to alternate day steroids in two children with a history of recurrent FSGS

FSGS is a common indication for kidney transplantation in children. However, transplantation is often complicated by recurrence of FSGS in the transplanted kidney, resulting in nephrotic syndrome and an increased risk of graft loss. Acute treatment strategies for recurrent FSGS include plasmapheresis and increased immunosuppressive therapy. There is little information on the long-term management of immunosuppression in these patients. We describe two children who were successfully treated with plasmapheresis for recurrent FSGS that occurred immediately post-transplant. Nephrotic syndrome reappeared years later when the patients were converted from daily to alternate day prednisone. In children with a history of FSGS, caution is necessary when altering the dosing schedule of prednisone.

IL-4 and many roads to lupuslike autoimmunity

Interleukin-4 (IL-4) is a multifunctional cytokine. Although most studies have focused on the B-cell stimulatory and Th2 promoting properties of IL-4 in the development of autoantibodies and autoantibody-mediated diseases, a few reports suggest a T-cell suppressor role for this cytokine in lupus. Since these properties of IL-4 may sometimes result in opposing outcomes, amplifying or inhibitory, on overall B-cell functions, it is not surprising that a few studies have found no role for IL-4 in the development of autoantibodies and lupus. Evidence for a more novel role for IL-4 in the development of lupus nephritis comes from recent studies, which suggests that IL-4 may directly promote extracellular matrix deposition in the glomeruli. Consistent with this idea, blockade of IL-4 by antibody treatment or of its signaling by inactivation of the Stat6 gene ameliorates glomerulosclerosis and delays or even prevents the development of end-stage renal disease, despite the presence of high levels of IgG anti-dsDNA Antibodies. Thus, IL-4 may serve multiple roles in the development of lupus: it may enhance autoantibody production via its direct B-cell effects, protect against autoimmunity via its T-cell suppressor effect, or perpetuate tissue damage via its direct effects on target organs.

[Vasoactive peptides and the development of renal sclerosis: contribution of transgenes]

Vasoactive peptides are implied in the development of renal sclerosis as evidenced by the efficiency of their antagonists in preventing glomerulosclerosis of experimental and human nephropathies. Genetically engineered models provide a new approach to investigate the mechanisms of the renal profibrotic actions of angiotensin II and endothelin. Overexpression of the human angiotensinogen and renin genes in rats induces renal sclerosis independently of changes in systemic hemodynamics. The same results are observed when the endothelin-1 gene is overexpressed in mice. Transgenic mice harboring the luciferase gene under the control of the collagen I-alpha 2 chain promoter (procol alpha 2[1]) and made hypertensive by induction of nitric oxide (NO) deficiency were used to study the renal profibrotic actions of vasoactive peptides. In this strain of mice, luciferase activity is an early index of renal fibrosis. Luciferase activity was increased in preglomerular arterioles and glomeruli when mice were deficient in NO. The pharmacological blockade of angiotensin II and endothelin prevented the development of renal sclerosis without modifying blood pressure. Moreover, when the endothelin receptor antagonist was administered after the development of renal fibrosis, preformed glomerulosclerosis partially regressed. Acute administration of vasoactive peptides and TGF-beta in transgenic procol alpha 2[1] mice showed that the angiotensin II activation of collagen I gene requires participation and/or cooperation of endothelin and TGF-beta. Recent data suggest that the profibrotic actions of vasoactive peptides also need the activation of EGF receptor, ERK and rho kinase pathways in renal and vascular cells.

Estrogen deficiency accelerates progression of glomerulosclerosis in susceptible mice

Estrogen deficiency may contribute to the development and progression of glomerulosclerosis in postmenopausal women. The responsiveness to estrogens could be controlled by genetic traits related to those that determine the susceptibility to glomerular scarring. This study was undertaken to determine whether the intensity of the sclerotic response was modified by the estrogen status in sclerosis-prone ROP Os/+ mice. Ovariectomized ROP Os/+ mice developed more severe renal dysfunction and glomerulosclerosis than intact, ie, estrogen sufficient age-matched female mice. Ovariectomized ROP Os/+ exhibited increased accumulation of extracellular matrix, predominantly of laminin, and a marked distortion of the glomerular architecture. We found an increase in macrophage infiltration in the mesangium of ovariectomized ROP Os/+. Estrogen deficiency decreased glomerular estrogen receptor expression in ROP Os/+ mice, which we had previously found to be low in the parental ROP strain. Thus, although physiological estrogen levels in young ROP Os/+ mice could not prevent the development of glomerulosclerosis, estrogen deficiency accelerated the progression of glomerular scarring in this mouse strain. This suggests that estrogen replacement will slow but not prevent the progression of glomerulosclerosis. It underscores the importance of the genetic composition of individuals that determines the susceptibility to diseases as well as the response to treatment.

Long-term dietary L-arginine supplementation attenuates proteinuria and focal glomerulosclerosis in experimental chronic renal transplant failure

Glomerular endothelial nitric oxide synthase expression is decreased in humans during acute rejection and chronic renal transplant failure (CRTF). This may contribute to vascular damage through changes in the renal hemodynamics and enhanced endothelial adhesion of leukocytes and platelets. Dietary supplementation of L-arginine may increase endothelial NO production, thereby protecting the vascular wall and improving renal hemodynamics. We tested the hypothesis that long-term L-arginine supplementation attenuates the development of CRTF in an experimental model for renal transplantation. In the Fisher 344 to Lewis rat model for renal transplantation, renal function and histology of untreated rats was compared with rats receiving L-arginine in the drinking water (10g/L), starting 2 days before transplantation. Every 4 weeks systolic blood pressure was measured and serum and urine were collected for measurement of nitrite and nitrate (NO(x)), creatinine, and proteinuria. At 34 weeks the histological renal damage was assessed by scoring focal glomerulosclerosis and measurement of alpha-smooth muscle actin (alpha-SMA) expression. Urinary NO(x) was significantly increased in treated animals. Proteinuria was significantly lower in L-arginine-treated animals from week 24 onward (p<0.05). Plasma creatinine and creatinine clearance did not differ between the groups. The focal and segmental glomerulosclerosis (FGS) score (max 400) at week 34 was also significantly lower in treated rats arbitrary U (20+/-21 vs 61+/-67 arbitrary U; p<0.05). The expression of alpha-SMA was lower in L-arginine-treated rats than in untreated rats (1.93+/-0.8% area surface vs 3.64+/-2.5% area surface). In conclusion, in this experimental model for CRTF, L-arginine administration significantly reduced FGS and proteinuria, without affecting renal function. Our data suggest that dietary L-arginine supplementation attenuates progression of CRTF and may therefore be an additional therapeutic option in human renal allograft recipients.

22-Oxacalcitriol prevents progressive glomerulosclerosis without adversely affecting calcium and phosphorus metabolism in subtotally nephrectomized rats

BACKGROUND

22-Oxacalcitriol (OCT), an analogue of vitamin D, has been shown to inhibit cell proliferation in cultured mesangial cells. OCT also prevented albuminuria and glomerular injury in an acute model of anti-Thy1 glomerulonephritis. However, potential side effects, including calcaemic actions and tubular dysfunction, of chronic OCT treatment remain unclear. In the present study, we evaluated the effect of OCT in a chronic model of progressive glomerulosclerosis in subtotally nephrectomized (SNX) rats.

METHODS

At one week after subtotal nephrectomy, SNX rats were divided into 3 groups having equivalent serum creatinine levels and body weight. OCT (0.08 or 0.4 micro g/kg body weight) was administered intravenously three times per week for 8 weeks to SNX rats. We evaluated effects of OCT on renal function during treatment and on morphologic parameters in glomeruli at 8 weeks. We additionally measured calcium and phosphate levels in serum and urine, and tubular dysfunction markers, including beta(2)-microgloblin (beta(2)m) and N-acetyl-beta-D-glycosaminidase (NAG) levels in urine.

RESULTS

OCT treatment significantly suppressed urinary albumin excretion, prevented increases in serum creatinine and serum urea nitrogen, and inhibited glomerular cell number, glomerulosclerosis ratio and glomerular volume in SNX rats at 8 weeks. At that time, OCT-treated groups did not show hypercalcaemia, hypercalciuria or hyperphosphaturia. Furthermore, OCT treatment did not affect beta(2)m or NAG levels in urine, and did not induce histological changes in tubular or interstitial regions.

CONCLUSIONS

These findings suggest that OCT may provide a clinically useful agent for preventing the progression of glomerulosclerosis without adversely affecting calcium and phosphorus metabolism or causing subsequent tubular dysfunction.

Different effects of 22-oxacalcitriol and calcitriol on the course of experimental chronic renal failure

Calcitriol, 1,25(OH)(2)D(3), has been reported to have a beneficial effect on bone histology in patients with predialysis chronic renal failure; however, such treatment involves a risk of hypercalcemia. To investigate the effects of 1,25(OH)(2)D(3) and 22-oxacalcitriol (OCT) on the progression of histologic deterioration, we administered intraperitoneal 1,25(OH)(2)D(3) or OCT, three times a week, to rats with adriamycin-induced progressive renal failure, from the 10th week after the induction of ADR-induced nephropathy. The rats were divided into the following groups: (1) high-dose 1,25(OH)(2)D(3), 0.2 microg/kg (group D(3)-0.2); (2) low-dose 1,25(OH)(2)D(3), 0.04 microg/kg (group D(3)-0.04); (3) high-dose OCT, 0.2 microg/kg (group OCT-0.2); (4) low-dose OCT, 0.04 microg/kg (group OCT-0.04); and (5) ADR-induced nephropathy (group ADR). The death rate at week 20 in group D(3)-0.2 was 50%, significantly higher than the death rates in the other groups, except for group D(3)-0.04 (P <.05). The serum creatinine and blood urea nitrogen levels were the highest in group D(3)-0.2, although the difference was not significant. In contrast, in groups OCT-0.2 and OCT-0.04, tubular changes and interstitial volume were smaller than in groups D(3)-0.2 and D(3)-0.04 (P <.05). Although calcium deposits increased in group D(3)-0.2, the difference was not significant. Glomerular expression of transforming growth factor-beta1 (TGF-beta1) expression was less in groups OCT-0.2 and OCT-0.04 than in groups D(3)-0.2 and D(3)-0.04 (P <.05). Glomerular fibronectin expression was less in group OCT-0.2 than in groups D(3)-0.2 and ADR (P <.05). Tubulointerstitial expression of TGF-beta1 was greater in group D(3)-0.2 than in group ADR and greater in group D(3)-0.04 than in group OCT-0.04 (P <.05). We conclude that a high dose of 1,25(OH)(2)D(3) accelerated the progressive renal deterioration of ADR-induced nephropathy, and, as a result, OCT was able to attenuate renal histologic lesions.

[The effect of tripterine in prevention of glomerulosclerosis in lupus nephritis mice]

OBJECTIVE

To study the protective effects of Tripterine on experimental lupus nephritis glomerulosclerosis.

METHODS

Different doses of Tripterine were injected peritoneally to BW F1 mice at different stages. 24-hour urine protein excretion, serum anti-dsDNA antibodies, renal pathology and RT-nested PCR were analyzed to study the preventive effects of Tripterine on LN glomerulosclerosis and its mechanisms.

RESULTS

(1) Tripterine suppressed the development of proteinuria, decreased the level of serum anti-dsDNA antibodies, reduced the expressions of collagen type IV, fibronectin, TIMP-1, TIMP-2, TGF-beta(1) and improved the expressions of MMP-1, -2 in the murine kidney. (2) The use of Tripterine before occurrence of proteinuria had more obvious protective effects than its use after the occurrence of proteinuria. (3) No significant difference was found between the 3 mg/kg/week Tripterine-treated-group and the 6 mg/kg/week Tripterine-treated-group. (4) No obvious change was observed in the expression of MMP-3.

CONCLUSIONS

Tripterine has a definite protective effect on glomerulosclerosis of the lupus murine model. The decrease of renal collagen type IV and fibronectin is probably due to its suppressive effect on the expressions of local TGF-beta(1) and TIMP-1, -2, and its improvement effect on the local expressions of MMP-1, -2. Tripterine may have no obvious influence on MMP-3 in this model.

Estrogen-related abnormalities in glomerulosclerosis-prone mice: reduced mesangial cell estrogen receptor expression and prosclerotic response to estrogens

The development and progression of glomerulosclerosis (GS) is determined by the genetic background. The incidence of end-stage renal disease is increased in postmenopausal women, suggesting that estrogen deficiency may play a role in the accumulation of extracellular matrix by mesangial cells (MCs), which are primarily responsible for the synthesis and degradation of this matrix. Using mouse models that are prone or resistant to the development of GS, we compared the expression of estrogen receptor (ER)-alpha and ER-beta subtypes in GS-prone and GS-resistant glomeruli and isolated MCs, and examined the effects of estrogens on ER, collagen, and matrix metalloproteinase (MMP) expression in MCs. Glomeruli and MCs from GS-prone mice had decreased expression of ER-alpha and ER-beta subtypes and ER transcriptional activity was also decreased in their MCs. Importantly, although 17 beta-estradiol treatment resulted in decreased collagen accumulation and increased MMP-9 expression and activity in MCs from GS-resistant mice, there was, paradoxically, no effect on collagen accumulation and decreased MMP-9 expression and activity in MCs from GS-prone mice. Thus, GS susceptibility is associated with diminished ER expression in MCs. The renal protective effects of estrogens, including decreased collagen accumulation and increased MMP-9 expression, seem to be blunted in GS-prone MCs.