Experimental and clinical rationale for use of MMF in nontransplant progressive nephropathies

Transient high salt intake causes epigenetic changes and leads to persistent inflammatory activation to produce "salt memory"

Transient high salt intake causes a sustained increase in blood pressure (BP) even after returning to a normal-salt diet, a phenomenon known as "salt memory." However, the molecular mechanisms of this phenomenon remain to be elucidated. Dahl salt-sensitive (SS) rats were fed a high-salt (8% NaCl) or high-salt diet and treated with drugs for 8 to 16 weeks and then returned to a normal-salt diet for 3 months. This study investigated the molecular mechanisms of salt memory and its mediation of SS hypertension and renal damage. We show that transient high salt intake caused persistent elevation of BP and exacerbation of kidney damage in Dahl SS rats even after returning to a normal-salt diet. Both epigenetic changes and inflammatory activation also persisted after resumption of a normal diet. Arterial BP, renal injury and the inflammatory response returned to normal levels in rats administered mycophenolate mofetil (MMF) during the 8-week period of high salt intake, resulting in the disappearance of salt memory. However, the vasodilator hydralazine did not ameliorate kidney damage or inflammatory activation, although it decreased BP to control levels. Transient high salt intake increased histone 3 lysine 4 monomethylation (H3K4me1) levels at the nuclear factor κB (NF-κB) subunit p65 promoter in SS rats, promoting p65 gene transcription and NF-κB activation and further leading to a series of inflammatory responses. Our findings demonstrate that transient high salt-induced epigenetic changes and persistent inflammatory activation play important roles in salt memory and its mediation of SS hypertension and renal damage.

Effect of mycophenolic acid in experimental, nontransplant glomerular diseases: new mechanisms beyond immune cells

Mycophenolic acid (MPA) was introduced into clinical practice as immunosuppressive drug therapy to prevent allograft rejection. Since then, its clinical application has widened. Our goal was to review the lessons learned from experimental nontransplant glomerular disease models on the mechanisms of MPA therapy. T and B lymphocytes are preferentially dependent on de novo purine synthesis. By inhibiting the rate-limiting enzyme of de novo purine synthesis, MPA depletes the pool of deoxyguanosine triphosphate (dGTP) and inhibits proliferation of these immune cells. Furthermore, MPA can also induce apoptosis of immune cells and is known to inhibit synthesis of fucose- and mannose-containing membrane glycoproteins altering the surface expression and binding ability of adhesion molecules. However, MPA exerts a direct effect also on nonimmune cells. Mesangial cells are partially dependent on de novo purine biosynthesis and are thus susceptible to MPA treatment. Additionally, MPA can inhibit apoptosis in podocytes and seems to be beneficial in preserving the expression of nephrin and podocin, and by attenuation of urokinase receptor expression leads to decreased foot-process effacement. In summary, our manuscript sheds light on the molecular mechanisms underlying the antiproteinuric effect of MPA. Overall, MPA is an excellent treatment option in many immunologic glomerulopathies because it possesses immunosuppressive properties, has a remarkable effect on nonimmune cells and counteracts the proliferation of mesangial cells, expansion of mesangial matrix, and foot-process effacement of podocytes combined with a low systemic toxicity.

Infiltrating immune cells in the kidney in salt-sensitive hypertension and renal injury

The importance of the immune system in hypertension, vascular disease, and renal disease has been appreciated for over 50 years. Recent experimental advances have led to a greater appreciation of the mechanisms whereby inflammation and immunity participate in cardiovascular disease. In addition to the experimental data, multiple studies in patients have demonstrated a strong correlation between the observations made in animals and humans. Of great interest is the development of salt-sensitive hypertension in humans with the concurrent increase in albumin excretion rate. Experiments in our laboratory have demonstrated that feeding a high-NaCl diet to Dahl salt-sensitive (SS) rats results in a significant infiltration of T lymphocytes into the kidney that is accompanied by the development of hypertension and renal disease. The development of disease in the Dahl SS closely resembles observations made in patients; studies were therefore performed to investigate the pathological role of infiltrating immune cells in the kidney in hypertension and renal disease. Pharmacological and genetic studies indicate that immune cell infiltration into the kidney amplifies the disease process. Further experiments demonstrated that infiltrating T cells may accentuate the Dahl SS phenotype by increasing intrarenal ANG II and oxidative stress. From these and other data, we hypothesize that infiltrating immune cells, which surround the blood vessels and tubules, can serve as a local source of bioactive molecules which mediate vascular constriction, increase tubular sodium reabsorption, and mediate the retention of sodium and water to amplify sodium-sensitive hypertension. Multiple experiments remain to be performed to refine and clarify this hypothesis.

The anti-fibrotic effect of mycophenolic acid-induced neutral endopeptidase

Mycophenolic acid (MPA) appears to have anti-fibrotic effects, but the molecular mechanisms underlying this are unknown. We prospectively studied 35 stable kidney transplant recipients maintained on cyclosporine and azathioprine. We converted 20 patients from azathioprine to enteric-coated mycophenolate sodium (EC-MPS) and continued the remaining 15 patients on azathioprine. Exploratory mRNA expression profiling, performed on five randomly selected EC-MPS patients, revealed significant upregulation of neutral endopeptidase (NEP), which is an enzyme that degrades angiotensin II. We confirmed these microarray data by measuring levels of NEP expression in all subjects; in addition, we found that NEP gene expression correlated inversely with proteinuria. In an additional 33 patients, glomerular and tubular NEP protein levels from renal graft biopsies were significantly higher among the 13 patients receiving cyclosporine + EC-MPS than among the 12 patients receiving cyclosporine + azathioprine or 8 patients receiving cyclosporine alone. Glomerular NEP expression inversely correlated with glomerulosclerosis and proteinuria, and tubular NEP expression inversely correlated with interstitial fibrosis. Incubation of human proximal tubular cells with MPA increased NEP gene expression in a dose- and time-dependent manner. Moreover, MPA reduced angiotensin II-induced expression of the profibrotic factor plasminogen activator inhibitor-1, and a specific NEP inhibitor completely reversed this effect. Taken together, our data suggest that MPA directly induces expression of neutral endopeptidase, which may reduce proteinuria and slow the progression of renal damage in kidney transplant recipients.

Treatment of the post-ischaemic inflammatory syndrome of diabetic nephropathy

BACKGROUND

Diabetes mellitus and its complications are a public health problem of epidemic proportions. Both diabetes and chronic kidney disease (CKD) increase the risk of acute kidney injury (AKI). Months after a single episode of acute ischaemia to the diabetic kidney, we have found an accelerated progression of nephropathy, with impaired function, severe renal inflammation, microvascular dysfunction, fibrosis and apoptotic cell death. We termed this entity the post-ischaemic inflammatory syndrome. We now test the hypothesis that blocking inflammation ameliorates the post-ischaemic inflammatory syndrome.

METHODS

Obese-diabetic ZS rats (F(1) hybrids of spontaneously hypertensive heart failure and Zucker fatty diabetic rats) were treated with mycophenolate mofetil (MMF), subjected to renal ischaemia or sham surgery, and monitored via the powerful technique of intravital microscopy.

RESULTS

Amelioration of post-ischaemia inflammation with MMF therapy improved long-term renal function, microvascular dysfunction, fibrosis and apoptosis.

CONCLUSION

These data support the hypothesis that the post-ischaemic inflammatory syndrome accelerates diabetic CKD, is a critical determinant of injury, and can be successfully treated.

The lymphocyte migration inhibitor FTY720 attenuates experimental hypertensive nephropathy

The lymphocyte migration inhibitor FTY720 attenuates experimental hypertensive nephropathy. Infiltration with lymphocytes is found in both immune and nonimmune chronic kidney diseases. In a rat model of immune-initiated progressive glomerulosclerosis, selective inhibition of lymphocyte infiltration by FTY720 showed significant beneficial effects on renal fibrosis. To test whether this translates into hypertensive nephropathy (HN), the lymphocyte migration inhibitor was administered to rats following nephrectomy. Two days after surgery, male Wistar rats were allocated to the following groups: Sham surgery, nephrectomy (HN), and HN + FTY720 (0.3 mg/kg body wt). Therapy was continued for 6 wk. Treatment with FTY720 was found to selectively reduce blood lymphocyte counts by 85% (P < 0.001 vs. HN) and renal lymphocyte infiltration (CD-3 positive cells) by 63% (P < 0.01 vs. HN) as was anticipated. Lymphocyte depletion went along with a significant reduction in proteinuria (-28%), whereas hypertensive systemic blood pressure remained unchanged (160 +/- 5 vs. 161 +/- 5 mmHg, P = not significant). The markedly increased histological tubulointerstitial and glomerular matrix protein accumulation, collagen, laminin, and fibronectin deposition were all significantly impeded in the FTY720-treated animals. The anti-fibrotic effects of FTY720 were paralleled by significant reductions in renal transforming growth factor (TGF)-beta overexpression, macrophage infiltration, and cell proliferation. In conclusion, the lymphocyte migration inhibitor FTY720 significantly limits histological and molecular fibrosis in a model of hypertensive nephropathy without affecting increased systemic blood pressure. Prevention of renal lymphocytes' infiltration by FTY720 was followed by significant reductions in TGF-beta overexpression, macrophage infiltration, and renal cell proliferation. These results suggest that infiltrating lymphocytes play an active, profibrotic role in the progression of hypertensive renal tissue injury.

Increased mast cell number in human hypertensive nephropathy

Mast cells have recently been related to nonallergic chronic organ damage and fibrosis. In the present study, we analyzed mast cell number, localization, and maturation in the kidney of a relatively unique group of middle-aged accident victims with primary essential hypertension and in normotensive controls (n=8 per group, Caucasians, predominantly male). Hypertensive kidneys showed a significantly higher degree of arteriolosclerosis. However, glomerular and tubulointerstitial matrix accumulation did not differ significantly to normotensive controls indicating a relatively early stage of hypertensive nephropathy. Using toluidine blue staining, renal mast cell number was found to be fivefold higher in hypertensive subjects compared with normotensive controls. Mast cells were primarily located in the peritubular interstitial spaces, some perivascular, but not in glomeruli. In a series of immunohistological staining studies, mast cell maturation grading showed that expression of early hematopoietic precursor cell marker CD34 did not differ between both groups. In contrast, mast cells were mostly positive for IgE receptor, tryptase, and chymase indicating a mature, differentiated cell phenotype in hypertensive nephropathy. Renal expression of stem cell factor was markedly upregulated in primary hypertension. Kidney macrophage and lymphocyte numbers were similar in both groups. In conclusion, human hypertensive kidney disease shows an early and conspicuous upregulation of stem cell factor along with an increased number of mature mast cells. The results suggest that renal mast cell accumulation may play a role in the pathogenesis of human hypertensive nephropathy.

The Impact of Renal Allograft Function on Exposure and Elimination of Mycophenolic Acid (MPA) and Its Metabolite MPA 7-O-glucuronide

BACKGROUND

Previous studies have shown that total-body clearance of mycophenolic acid (MPA) is increased and total MPA exposure decreased in renal allograft recipients with severe renal dysfunction. In contrast to these studies, other studies have associated renal impairment with higher MPA exposure. The reason for these inconsistencies is not clear.

METHODS

In 120 renal allograft recipients with stable graft function and treated with a combination of mycophenolate mofetil, tacrolimus, and corticosteroids, clinical determinants of exposure to total MPA and its glucuronide metabolite MPA 7-O-glucuronide (MPAG) were investigated in a multivariate regression model at 3 (n=118) and 12 (n=63) months after transplantation.

RESULTS

Almost 50% of total MPA exposure could be explained by the final model, in which proteinuria, glomerular filtration rate, diabetes mellitus, and the mycophenolate mofetil dose were independent determinants of total MPA exposure. Lower glomerular filtration rate (GFR) was independently associated with higher MPA exposure both at 3 and 12 months after transplantation. GFR, alanine aminotransferase, and serum albumin levels and mycophenolate mofetil dose explained 69% of total MPAG exposure variability.

CONCLUSION

In stable renal recipients, total MPA exposure negatively associates with renal function, through accumulation of both MPA and MPAG in patients with moderately reduced renal allograft function. This is in contrast to severe graft dysfunction, where MPA clearance is higher due to increased free fraction of MPA, as shown in previous studies. The duality in the effect of graft function on MPA pharmacokinetics is of clinical importance, adjusting mycophenolate mofetil dose according to renal function might help to avoid side effects and improve efficacy.

[Pathophysiology of kidney disease progression]

Nephron reduction increases the filtration capacity of the remaining nephrons, which is helpful in the short term, but harmful over the long term The increase in glomerular capillary pressure and in hypertrophy of healthy nephrons stimulates the renin-angiotensin system and TGF-beta. Myofibroblastic transdifferentiation follows, with fibrogenesis and glomerulosclerosis. Converting enzyme inhibitors reduce the expression of genes coding for profibrotic molecules. Proteinuria promotes interstitial fibrosis and must be reduced by drugs that block the renin-angiotensin system.

Lipotoxic and inflammatory phenotypes in rats with uncontrolled metabolic syndrome and nephropathy

Anomalous inflammatory responses triggered by the metabolic syndrome cause renal injury. This discovery links renal lipid accumulation with lipotoxicity to inflammation and may explain the insidious fibrosis and cellular decay characteristic of nephropathy in the metabolic syndrome. However, it is not clear whether control of inflammation protects the kidney independently of lipid accumulation, which is a required step for lipotoxicity in hyperglycemia and dyslipidemia. We hypothesized that in rats with the metabolic syndrome, and overt nephropathy, treatment with mycophenolate mofetil (MMF; 10 mg.kg(-1).day(-1) ip for 14 wk) would reduce the abnormal renal lipid depots and limit renal inflammation and injury. We studied groups of lean and obese F1 hybrid Zucker fatty diabetic/spontaneous hypertensive heart failure (ZS) rats. MMF did not affect lean rats. In obese ZS rats, MMF did not change severe hyperglycemia or the higher kidney loads of unutilized lipid and peroxidation products. Nonetheless, MMF dramatically reduced diabetes/obesity-derived systemic and renal inflammation, limited renal size, hyperfiltration, and fibrosis. These data indicate that in rats, anti-inflammatory therapy presumably acting downstream, and independently of lipotoxicity, can effectively limit renal injury and fibrosis.

S1P modulator FTY720 limits matrix expansion in acute anti-thy1 mesangioproliferative glomerulonephritis

FTY720 is a novel immune modulator whose primary action is blood lymphocyte depletion through interaction with sphingosine-1-phosphate (S1P) receptors. The present study analyzes the effect of FTY720 on both the early mesangial cell injury and the subsequent matrix expansion phase of experimental mesangioproliferative glomerulonephritis. Disease was induced by injection of OX-7 anti-thy1 antibody into male Wistar rats. In both protocols, FTY720 administration (0.3 mg/kg body wt) resulted in a selective and very marked reduction in blood lymphocyte count. In the injury experiment, the S1P receptor modulator was given starting 5 days before and continued until 1 day after antibody injection. FTY720 did not significantly affect the degree of anti-thy1-induced mesangial cell lysis and glomerular-inducible nitric oxide production. In the matrix expansion experiment, FTY720 treatment was started 1 day after antibody injection and continued until day 7. In this protocol, the S1P modulator reduced proteinuria, histological matrix expansion, and glomerular protein expression of TGF-beta(1), fibronectin, and PAI-1. Glomerular collagen III staining intensity was decreased. FTY720 reduced markedly glomerular lymphocyte number per cross section and to a lesser degree macrophage infiltration. In conclusion, FTY720 significantly limits TGF-beta(1) overexpression and matrix protein expression following induction of acute anti-thy glomerulonephritis, involving reductions in blood and glomerular lymphocyte numbers. The results suggest that lymphocytes actively contribute to matrix expansion in experimental mesangioproliferative glomerulonephritis. Our study expands on findings on FTY720's beneficial effects on tubulointerstitial and functional disease progression previously reported in anti-thy1-induced chronic glomerulosclerosis.

Change From Cyclosporine to Combination Therapy of Mycophenolic Acid With the New Sphingosine-1-phosphate Receptor Agonist, KRP-203, Prevents Host Nephrotoxicity and Transplant Vasculopathy in Rats

BACKGROUND

Replacement of calcineurin inhibitor (CI) with anti-metabolic agents in transplant patients with CI-induced nephrotoxicity is performed clinically and improves renal function, but increases the risk of rejection. We investigated whether the change from cyclosporine (CsA) to a limited dose of mycophenolic acid (MPA) together with a new sphingosine-1-phosphate (S1P) receptor agonist, KRP-203, is sufficient to prevent both transplant vasculopathy and CsA-induced nephrotoxicity.

METHODS

Orthotopic aortic transplantation was conducted in a high-responder rat combination of Dark Agouti (DA; major histocompatibility complex [MHC] haplotype RT-1a) to Lewis (RT-1(l)). After CsA administration (15 mg/kg/day) for 2 weeks, the recipients were divided into the following treatment groups for 6 weeks: MPA (10 mg/kg); KRP-203 (KRP; 1 mg/kg); and MPA + KRP. Serum creatinine (Cr), arteriolar hyalinosis and expression of transforming growth factor (TGF)-beta1 in the recipient kidney were examined as parameters indicating nephrotoxicity. Intimal hyperplasia was assessed by vascular occlusion, and graft-infiltrated cells were semi-quantitatively evaluated histologically and then characterized immunohistochemically.

RESULTS

Continuous CsA treatment attenuated intimal hyperplasia and cell infiltration (2.9 +/- 0.3% and 0.4 +/- 0.1; p < 0.01 vs vehicle), but increased Cr and hyalinosis (0.43 +/- 0.03 mg/dl and 57.2 +/- 0.4%; p < 0.01) with upregulated TGF-beta1. Replacement of CsA by MPA or KRP treatment alone improved nephrotoxicity, but worsened intimal hyperplasia and cell infiltration. Conversion to MPA + KRP treatment prevented nephrotoxicity (Cr, 0.32 +/- 0.02 mg/dl; hyalinosis, 5.6 +/- 1.3%; p < 0.01 vs CsA) and markedly suppressed intimal hyperplasia and cell infiltration (3.6 +/- 1.2% and 1.0 +/- 0.3; p = not significant vs CsA), with reduced T-cell infiltrates in the graft.

CONCLUSIONS

Changing from CsA to a combined therapy of MMF with S1P agonist is a promising strategy in clinical transplantation to overcome CI-induced nephrotoxicity and chronic rejection.

Immune Suppression Attenuates Hypertension and Renal Disease in the Dahl Salt-Sensitive Rat

Experiments were performed to determine the importance of activation or infiltration of immune cells in the kidney during the development of hypertension and renal disease in Dahl salt-sensitive rats (SS/Mcw) fed a 4.0% NaCl diet. Compared with vehicle-treated rats, chronic administration of mycophenolate mofetil ([MMF] 30 mg/kg per day, IP), an immunosuppressive agent that has cytostatic effects on T and B cells, decreased cell-specific markers of T and B cells by 50% to 60% in the kidneys of SS/Mcw rats (n=5 per group). Further studies were performed on Dahl SS/Mcw rats, which were instrumented with chronic indwelling catheters and studied after 3 weeks on the 4.0% NaCl diet. Rats were administered MMF or 5% dextrose vehicle daily during the 3-week period of high NaCl intake. Mean arterial blood pressure in the rats administered MMF (122±2 mm Hg; n=11) was significantly decreased compared with vehicle-treated rats (139±4 mm Hg; n=9). Furthermore, the rate of protein (112±13 mg per day) and albumin excretion (15±3 mg per day) in the MMF-treated rats was significantly lower than the protein and albumin excretion rate in vehicle-treated rats (167±25 and 31±7 mg per day, respectively). Creatinine clearance and body weight were not different between the groups, averaging 0.52±0.08 mL/min per gram kidney weight and 322±10 g, respectively, in the MMF-treated group. These experiments indicate that the activation of the immune system or renal infiltration of immune cells plays an important role in the development of hypertension and renal disease in Dahl SS/Mcw rats consuming an elevated NaCl diet.

Macrophages and progressive tubulointerstitial disease

Macrophages and progressive tubulointerstitial disease. In chronic renal disease, tubulointerstitial inflammation and injury is associated with infiltrating macrophages. As a consequence of primary injury, proteinuria, chronic hypoxia, and glomerular-derived cytokines may all differentially modulate the expression of factors that promote macrophage recruitment. In addition to adhesion molecules and chemokines, products of complement system and renin-angiotensin system activation may direct this process. Once present at interstitial sites, macrophages interact with resident cells and extracellular matrix to generate a proinflammatory microenvironment that amplifies tissues injury and promotes scarring. There is now increasing evidence for the efficacy of interventions directed against factors that recruit, activate, or are produced by macrophages. A detailed understanding of the biology of this area may lead to the further development of therapies that will improve the outcome of renal disease.

15-Deoxyspergualin and cyclophosphamide, but not mycophenolate mofetil, prolong survival and attenuate renal disease in a murine model of ANCA-associated crescentic nephritis

BACKGROUND

Here we compare the efficacy of cyclophosphamide (CYC) for treatment of crescentic nephritis (CGN) with the newer immunosuppressants 15-deoxyspergualin (DSG) and mycophenolate mofetil (MMF) in SCG/Kj mice, an inbred mouse strain that spontaneously develops CGN, systemic necrotizing vasculitis and antineutrophil cytoplasmic antibodies (ANCAs).

METHODS

Mice were randomly assigned to intraperitoneal treatment with either DSG (2 mg/kg/day), CYC (50 mg/kg/week), MMF (60 or 100 mg/kg/day) or vehicle (VEH, dextrose 5% 0.3 ml/day) beginning at the 10th week of life. ANCA, blood urea nitrogen (BUN) and proteinuria were determined in all animals regularly, and survival was calculated. Renal histology was obtained in the 18th week of life in the MMF- or VEH-treated groups and in the 24th week in DSG- or CYC-treated animals.

RESULTS

Mean survival in VEH-treated animals was 123 days. At that point, survival was 100% in the CYC- or DSG-treated animals (P<0.001). Survival in the MMF group (pooled data) was not significantly different from the VEH-treated animals [MMF, 117 days (95% CI 108-127)]. BUN (18th week, CYC 43+/-9 mg/dl and DSG 36+/-6 mg/dl vs VEH 73+/-28 mg/dl, P<0.001, MMF 66+/-26 mg/dl), 24 h proteinuria (18th week, CYC 0.4+/-0.2 mg and DSG 0.7+/-0.6 mg vs VEH 2.7+/-3 mg, P<0.001, MMF 2.2+/-3 mg) crescent formation (18th week, VEH 42+/-9%, MMF 39+/-11%; CYC 5+/-2% and DSG 22+/-7% vs VEH, P<0.05), glomerular immune complex deposition, and ANCA formation were significantly improved in CYC- and DSG- but not in MMF-treated animals when compared with controls.

CONCLUSION

DSG and CYC, but not MMF, prolong life, limit renal damage and prevent autoantibody formation in SCG/Kj mice.

Hypertension in Page (cellophane-wrapped) kidney is due to interstitial nephritis

BACKGROUND

Cellophane wrapping of the kidneys (Page kidney) induces perinephrits and hypertension, assumed to be due to renal ischemia resulting from parenchymal compression by the fibrous hull surrounding the kidneys. We investigated if interstitial nephritis, rather than plasma angiotensin activity, played a role in the development of hypertension in the Page kidney model.

METHODS

We followed for 7 weeks rats with bilateral cellophane wrapping of the kidneys that received 20 mg/kg/day of the immunosuppressive antiproliferative drug mycophenolate mofetil (MMF) (two-kidney wrap/MMF) (N = 10) or vehicle (two-kidney wrap) (N = 10), and sham-operated rats (N = 10).

RESULTS

The two-kidney wrap group had progressive increment in blood pressure, inflammatory damage occupying 25% to 50% of the renal tubulointerstitial region and increased number of angiotensin II-positive cells, angiotensin II content, and oxidative stress in the kidney. MMF treatment prevented the development of hypertension and renal inflammation without modifying the perinephritic hull or the increment it induced in the intrarenal pressure. The plasma levels of angiotensin II were similar in the two-kidney wrap group, the two-kidney wrap/MMF group and the sham-operated animals and unchanged from baseline, despite the blood pressure increase in the two-kidney wrap group.

CONCLUSION

Our results indicate that renal wrap hypertension is unrelated to plasma angiotensin II levels and related to the inflammatory damage caused by the external compression of the kidney.

Mycophenolate mofetil slows progression in anti-thy1-induced chronic renal fibrosis but is not additive to a high dose of enalapril

Tubulointerstitial inflammation and fibrosis are hallmarks of chronic progressive renal diseases. To characterize the functional interaction between cell infiltration and matrix expansion, this study compared the immunosuppressant mycophenolate mofetil (MMF), intended as primarily anti-inflammatory intervention, the angiotensin-converting enzyme inhibitor enalapril, intended as primarily an anti-fibrotic drug, and a combination of both as anticipated anti-inflammatory/anti-fibrotic intervention. The model used was anti-thy1-induced chronic-progressive glomerulosclerosis (cGS) in the rat, where a brief anti-thy1-induced glomerular injury progresses spontaneously toward tubulointerstitial fibrosis and renal insufficiency. cGS was induced by injection of anti-thy1 antibody into uninephrectomized Wistar rats. One week after disease induction, animals were randomly assigned to the following groups: cGS, cGS plus MMF (20 mg·kg body wt−1·day−1), cGS plus high-dose enalapril (12 mg·kg body wt−1·day−1), and cGS plus both. At week 16 after disease induction, MMF or enalapril alone reduced signs of chronic renal disease significantly and similarly compared with the untreated cGS group. Variables measured included proteinuria, blood pressure, tubulointerstitial and glomerular matrix accumulation, expression of transforming growth factor-β1, fibronectin, and plasminogen activator inhibitor-1, infiltration of lymphocytes and macrophages, plasma creatinine and urea levels, and glomerular filtration rate. Combined MMF and enalapril treatment was not superior to single therapy. In conclusion, MMF slows the progression of chronic renal fibrosis and renal insufficiency as effectively as high-dose enalapril in the anti-thy1-induced chronic-progressive glomerulosclerosis model. The dual anti-inflammatory/anti-fibrotic intervention does not yield additive renoprotective effects, indicating that MMF and enalapril interfere with similar or very closely related pathways involved in progression of renal disease.

Mycophenolate mofetil and roscovitine decrease cyclin expression and increase p27(kip1) expression in anti Thy1 mesangial proliferative nephritis

The response of mesangial cells to a phlogistic challenge includes cell proliferation and mesangial matrix expansion. Cell proliferation is a highly regulated process which includes enhancing factors such as cyclins, cyclin dependent kinases, and inhibitory proteins, such as p27(kip1). The aim of the study was to evaluate the effects of Mycophenolate mofetil (MMF), and roscovitine (R), on the cell cycle regulatory system when administered in the florid phase of the experimental model of mesangial proliferative nephritis induced by the anti Thy-1 antigen monoclonal antibody. Three days after nephritis induction, different groups were given MMF and R. Rats treated with MMF or R showed a slight decrease in mesangial proliferation and matrix expansion. Samples of cortical tissue were tested by 'real time' RT-PCR in order to study gene expression of cyclins B, D1, D2, D3, E, and the cyclin inhibitor p27(kip1). Localization of mRNA was evaluated by in situ hybridization. Real time RT-PCR analysis showed a significant decrease in cyclins B, D1, D2, and D3 in rats treated with either MMF or R as compared to controls. Both MMF and R treatment induced a significant increase in p27(kip1) mRNA expression. In situ hybridization showed a mesangial-endothelial expression pattern in glomeruli. The number of labelled cells per glomerulus, the number of positive glomeruli in each examined slide as well as cyclin D2 and D3 signal intensity was significantly lower in rats treated with MMF or R as compared to controls, whereas MMF or R treatment up-regulated p27(kip1) mRNA expression. Immunohistochemical evaluation of p27(kip1) aimed to examine the influence of MMF or R on protein expression confirmed up-regulation.

Mycophenolate mofetil in IgA nephropathy: results of a 3-year prospective placebo-controlled randomized study

BACKGROUND

Because humoral immunity is believed to play a pivotal role in the pathogenesis of IgA nephropathy (IgAN), a prospective placebo-controlled randomized study was started in patients with IgAN using mycophenolate mofetil (MMF).

METHODS

A total of 34 patients with IgAN were treated with salt intake restriction, angiotensin-converting enzyme (ACE) inhibition and MMF 2 g per day (N= 21) or placebo (N= 13). After 36 months of follow-up clinical, biochemical, and radiologic data were analyzed using linear mixed models for longitudinal data and Kaplan-Meier survival analysis.

RESULTS

Therapy had to be stopped prematurely in five patients. Two patients (MMF group) evolved to end-stage renal disease (ESRD). There was no difference between groups in the percentage of patients with a decrease of 25% or more in the inulin clearance or with a serum creatinine increase of 50% or more over 3 years. There was also no significant difference between groups in annualized rate of change of serum creatinine, computed by linear regression analysis. No significant difference was noted between groups for inulin clearance, serum creatinine, proteinuria, blood pressure, or other parameters of renal function. Hemoglobin and C-reactive protein were significantly lower in the MMF group compared with the placebo group. As a function of time, a significant decline in both groups was noted of proteinuria, parenchymal thickness of the kidneys and C3d.

CONCLUSION

In patients with IgAN at risk for progressive disease, no beneficial effect of 3-year treatment with MMF 2 g per day could be demonstrated on renal function/outcome or proteinuria. However, larger randomized studies are needed to confirm or reject these results.

Oxidative stress, renal infiltration of immune cells, and salt-sensitive hypertension: all for one and one for all

Recent evidence indicates that interstitial infiltration of T cells and macrophages plays a role in the pathogenesis of salt-sensitive hypertension. The present review examines this evidence and summarizes the investigations linking the renal accumulation of immune cells and oxidative stress in the development of hypertension. The mechanisms involved in the hypertensive effects of oxidant stress and tubulointerstitial inflammation, in particular intrarenal ANG II activity, are discussed, focusing on their potential for sodium retention. The possibility of autoimmune reactivity in hypertension is raised in the light of the proinflammatory and immunogenic pathways stimulated by the interrelationship between oxidant stress and inflammatory response. Finally, we present some clinical considerations derived from the recognition of this interrelationship.