Beneficial effect of the inosine monophosphate dehydrogenase inhibitor mycophenolate mofetil on survival and severity of glomerulonephritis in systemic lupus erythematosus (SLE)-prone MRLlpr/lpr mice

Polydatin effectively attenuates disease activity in lupus-prone mouse models by blocking ROS-mediated NET formation

Background

Neutrophil extracellular trap (NET) formation has been described to be closely involved in the pathogenesis of systemic lupus erythematosus (SLE). In this study, we aimed to investigate the effect of polydatin (PD) on NET formation and its effects on disease activity in lupus-prone mouse models.

Methods

In vitro, neutrophils from SLE patients and healthy people stimulated with phorbol 12-myristate 13-acetate (PMA) or phosphate-buffered saline (PBS) were treated with PD, and reactive oxygen species (ROS) production and NET formation examined. In vivo, pristane-induced lupus (PIL) mice were treated with vehicle, PD, mycophenolate mofetil (MMF) or cyclophosphamide (CYC) while MRL/lpr mice were treated with vehicle or PD. Proteinuria, serum autoantibodies, ROS production, NET formation and kidney histopathology were tested.

Results

Consistent with previous findings, blood neutrophils from SLE patients showed increased spontaneous NET formation. Both in vivo and in vitro, PD treatment significantly inhibited ROS production and NET release by neutrophils. In MRL/lpr mouse model, PD administration reduced the proteinuria, circulating autoantibody levels, and deposition of NETs and immune complex in the kidneys. In addition, PD treatment ameliorated lupus-like features in PIL mice as MMF or CYC did.

Conclusions

PD treatment inhibited ROS-mediated NET formation and ameliorated lupus manifestations in both PIL mice and MRL/lpr mice. These results highlight the involvement of NETosis in SLE pathogenesis and reveal that PD might be a potential therapeutic agent for SLE or other autoimmune diseases.

Modelling clinical systemic lupus erythematosus: similarities, differences and success stories

Mouse models of SLE have been indispensable tools to study disease pathogenesis, to identify genetic susceptibility loci and targets for drug development, and for preclinical testing of novel therapeutics. Recent insights into immunological mechanisms of disease progression have boosted a revival in SLE drug development. Despite promising results in mouse studies, many novel drugs have failed to meet clinical end points. This is probably because of the complexity of the disease, which is driven by polygenic predisposition and diverse environmental factors, resulting in a heterogeneous clinical presentation. Each mouse model recapitulates limited aspects of lupus, especially in terms of the mechanism underlying disease progression. The main mouse models have been fairly successful for the evaluation of broad-acting immunosuppressants. However, the advent of targeted therapeutics calls for a selection of the most appropriate model(s) for testing and, ultimately, identification of patients who will be most likely to respond.

Cathepsin S inhibition combines control of systemic and peripheral pathomechanisms of autoimmune tissue injury

Cathepsin(Cat)-S processing of the invariant chain-MHC-II complex inside antigen presenting cells is a central pathomechanism of autoimmune-diseases. Additionally, Cat-S is released by activated-myeloid cells and was recently described to activate protease-activated-receptor-(PAR)-2 in extracellular compartments. We hypothesized that Cat-S blockade targets both mechanisms and elicits synergistic therapeutic effects on autoimmune tissue injury. MRL-(Fas)lpr mice with spontaneous autoimmune tissue injury were treated with different doses of Cat-S inhibitor RO5459072, mycophenolate mofetil or vehicle. Further, female MRL-(Fas)lpr mice were injected with recombinant Cat-S with/without concomitant Cat-S or PAR-2 blockade. Cat-S blockade dose-dependently reversed aberrant systemic autoimmunity, e.g. plasma cytokines, activation of myeloid cells and hypergammaglobulinemia. Especially IgG autoantibody production was suppressed. Of note (MHC-II-independent) IgM were unaffected by Cat-S blockade while they were suppressed by MMF. Cat-S blockade dose-dependently suppressed immune-complex glomerulonephritis together with a profound and early effect on proteinuria, which was not shared by MMF. In fact, intravenous Cat-S injection induced severe glomerular endothelial injury and albuminuria, which was entirely prevented by Cat-S or PAR-2 blockade. In-vitro studies confirm that Cat-S induces endothelial activation and injury via PAR-2. Therapeutic Cat-S blockade suppresses systemic and peripheral pathomechanisms of autoimmune tissue injury, hence, Cat-S is a promising therapeutic target in lupus nephritis.

Adhesion molecules, mycophenolate mofetil and systemic lupus erythematosus

Mycophenolate mofetil (MMF) has been reproducibly shown to inhibit lymphocyte adhesion and penetration of endothelial cell surfaces. The mechanism is not yet elucidated. In vitro studies on the effects of MMF on cell adhesion molecules (CAM) using human umbilical vein endothelial cells (HUVEC) have shown conflicting results. Different studies have independently shown that MMF increased, decreased or had no effect on intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1). Several studies suggest MMF may reduce the endothelial expression of E-selectin. Recent studies have been unable to replicate initial work, which suggested that MMF impaired glycosylation of lymphocyte CAM. The same studies concluded that MMF had no effect on the surface expression of lymphocyte CAM, but altered the binding ability of these molecules. ICAM-1/LFA-1 (lymphocyte function-associated antigen-1), VCAM-1/VLA-4 (very late antigen-4) and P-selectin/PSGL-1 (P-selectin glycoprotein ligand-1) ligand pairs are most likely to be involved. Few in vivo and no conclusive human studies have been carried out. The literature relevant to cell adhesion molecules in systemic lupus erythematosus (SLE) is reviewed in detail.

Adhesion molecules, mycophenolate mofetil and systemic lupus erythematosus

Mycophenolate mofetil (MMF) has been reproducibly shown to inhibit lymphocyte adhesion and penetration of endothelial cell surfaces. The mechanism is not yet elucidated. In vitro studies on the effects of MMF on cell adhesion molecules (CAM) using human umbilical vein endothelial cells (HUVEC) have shown conflicting results. Different studies have independently shown that MMF increased, decreased or had no effect on intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1). Several studies suggest MMF may reduce the endothelial expression of E-selectin. Recent studies have been unable to replicate initial work, which suggested that MMF impaired glycosylation of lymphocyte CAM. The same studies concluded that MMF had no effect on the surface expression of lymphocyte CAM, but altered the binding ability of these molecules. ICAM-1/LFA-1 (lymphocyte function-associated antigen-1), VCAM-1/VLA-4 (very late antigen-4) and P-selectin/PSGL-1 (P-selectin glycoprotein ligand-1) ligand pairs are most likely to be involved. Few in vivo and no conclusive human studies have been carried out. The literature relevant to cell adhesion molecules in systemic lupus erythematosus (SLE) is reviewed in detail.

Mycophenolate mofetil in animal models of autoimmune disease

Mycofenolate mofetil (MMF-Cellcept) is an immunomodulatory drug utilized extensively in transplant medicine. The efficacy of regimes including Cellcept in preventing allograft rejection, and in the treatment of rejection, is now firmly established. The immunosuppressive actions of this drug enabled the investigation for the beneficial effects in autoimmune diseases. We review the evidence for the contribution of MMF in autoimmunity in animal models of systemic lupus erythematosus (SLE), mercury induced autoimmune glomerulonephritis, diabetes mellitus, experimental autoimmune uveoretinitis, and experimental allergic encephalitis. MMF has an influence on the T and B cell pathways. It is immunosuppressive and anti-inflammatory.

Mycophenolate mofetil and animal models

Mycophenolate mofetil (MMF), is the morpholinoethyl ester of mycophenolic acid (MPA). Though initially developed as an anti-rejection treatment, MMF is beginning to find application in more common immune-mediated diseases. MMF has been shown to be effective against transplant-associated vascular disease, lupus and other inflammatory diseases via multiple mechanisms in several animal models. MMF treatment blocks the proliferation of T cells and B cells, attenuates the production of autoreactive IgG and IgM, diminishes complement deposition, and reduces the production of multiple proinflammatory cytokines including TNF-α, IFN-γ, IL-2, IL-3, IL-4, IL-5, IL-6 and IL-12. It also increases production of the anti-inflammatory mediator IL-10. In addition, MMF reduces the infiltration of immune cells into sites of inflammation by interfering with the expression of cell-surface molecules critical for this process, including MHC class II, CD40, CD80, CD86, I-A, and ICAM-1. Additional mechanisms involving mannosylation and N-linked glycosylation of cell-surface molecules are only beginning to be investigated. This article will focus on the contribution of animal models of disease as investigational tools in the development of MMF as an immunomodulatory drug. The use of mice, rats, rabbits, monkeys, baboons and interspecific xenografts will be discussed.

Modulation of intra-pulmonary TGF-b expression by mycophenolate mofetil in lupus prone MRL/lpr mice

We investigated the expression profile of inflammatory cytokines in the lung of lupus-prone MRL/lpr mice and evaluated the therapeutic potential of mycophenolate mofetil (MMF) in reducing pulmonary cytokines in active lupus. Eight-week old female MRL/lpr mice ( n = 20) were treated with MMF in vehicle by oral gavage. Disease control MRL/lpr mice ( n = 30) or normal control MRL mice ( n = 20) received vehicle alone. The mice were sacrificed after eight or 12 weeks of treatment. Gene expression and protein synthesis of IL-1β, MCP-1 and TGF-β1 in lung tissues were determined. We found an increase in the gene expression of IL-1β, MCP-1 and TGF-β1 in lung tissues of untreated MRL/lpr mice compared with MRL mice at either 16 weeks or 20 weeks of age. MMF treatment significantly prolonged the survival of MRL/lpr mice, down-regulated the gene expression of IL-1β, MCP-1 and TGF-β1 in lung tissues at the end of eight or 12 weeks of treatment. Protein synthesis of TGF-b1 was decreased following eight weeks of MMF treatment. We conclude that MMF treatment can reduce the TGF-b1 gene expression and protein synthesis in lung tissues of lupus-prone mice. Our findings provide experimental data suggesting a beneficial potential of MMF therapy in pulmonary involvement of lupus.

Immunosuppression-Independent Role of Regulatory T Cells against Hypertension-Driven Renal Dysfunctions

Hypertension-associated cardiorenal diseases represent one of the heaviest burdens for current health systems. In addition to hemodynamic damage, recent results have revealed that hematopoietic cells contribute to the development of these diseases by generating proinflammatory and profibrotic environments in the heart and kidney. However, the cell subtypes involved remain poorly characterized. Here we report that CD39(+) regulatory T (TREG) cells utilize an immunosuppression-independent mechanism to counteract renal and possibly cardiac damage during angiotensin II (AngII)-dependent hypertension. This mechanism relies on the direct apoptosis of tissue-resident neutrophils by the ecto-ATP diphosphohydrolase activity of CD39. In agreement with this, experimental and genetic alterations in TREG/TH cell ratios have a direct impact on tissue-resident neutrophil numbers, cardiomyocyte hypertrophy, cardiorenal fibrosis, and, to a lesser extent, arterial pressure elevation during AngII-driven hypertension. These results indicate that TREG cells constitute a first protective barrier against hypertension-driven tissue fibrosis and, in addition, suggest new therapeutic avenues to prevent hypertension-linked cardiorenal diseases.

Hirschsprung-like disease is exacerbated by reduced de novo GMP synthesis

Hirschsprung disease (HSCR) is a partially penetrant oligogenic birth defect that occurs when enteric nervous system (ENS) precursors fail to colonize the distal bowel during early pregnancy. Genetic defects underlie HSCR, but much of the variability in the occurrence and severity of the birth defect remain unexplained. We hypothesized that nongenetic factors might contribute to disease development. Here we found that mycophenolate, an inhibitor of de novo guanine nucleotide biosynthesis, and 8 other drugs identified in a zebrafish screen impaired ENS development. In mice, mycophenolate treatment selectively impaired ENS precursor proliferation, delayed precursor migration, and induced bowel aganglionosis. In 2 different mouse models of HSCR, addition of mycophenolate increased the penetrance and severity of Hirschsprung-like pathology. Mycophenolate treatment also reduced ENS precursor migration as well as lamellipodia formation, proliferation, and survival in cultured enteric neural crest–derived cells. Using X-inactivation mosaicism for the purine salvage gene Hprt, we found that reduced ENS precursor proliferation most likely causes mycophenolate-induced migration defects and aganglionosis. To the best of our knowledge, mycophenolate is the first medicine identified that causes major ENS malformations and Hirschsprung-like pathology in a mammalian model. These studies demonstrate a critical role for de novo guanine nucleotide biosynthesis in ENS development and suggest that some cases of HSCR may be preventable.

Mycophenolic acid counteracts B cell proliferation and plasmablast formation in patients with systemic lupus erythematosus

Introduction

Clinical trials revealed a high efficacy of mycophenolate mofetil (MMF) in inducing and maintaining remission in patients with class III-V-lupus nephritis. Also extrarenal manifestations respond to MMF treatment. However, few attempts have been undertaken to delineate its mechanism of action in systemic lupus erythematosus (SLE) a disease characterized by enhanced B cell activation.

Methods

Clinical and paraclinical parameters of 107 patients with SLE were recorded consecutively and analyzed retrospectively. Patients were divided into treatment groups (MMF: n = 39, azathioprine (AZA) n = 30 and controls without immunosuppressive therapy n = 38). To further delineate the effect of mycophenolic acid (MPA) on naive and memory B cells in vitro assays were performed.

Results

Although patients taking AZA flared more frequently than patients on MMF or controls, the analysis of clinical parameters did not reveal significant differences. However, profound differences in paraclinical parameters were found. B cell frequencies and numbers were significantly higher in patients taking MMF compared to those on AZA but lower numbers and frequencies of plasmablasts were detected compared to AZA-treated patients or controls. Notably, MMF treatment was associated with a significantly higher frequency and number of transitional B cells as well as naive B cells compared to AZA treatment. Differences in T cell subsets were not significant. MPA abrogated in vitro proliferation of purified B cells completely but had only moderate impact on B cell survival.

Conclusions

The thorough inhibition of B cell activation and plasma cell formation by MMF might explain the favorable outcomes of previous clinical trials in patients with SLE, since enhanced B cell proliferation is a hallmark of this disease.

Mycophenolate mofetil in the treatment of lupus nephritis

Lupus nephritis is a complication of systemic lupus erythematosus, which has significant morbidity and mortality. The accepted standard of treatment for severe lupus nephritis is cyclophosphamide for induction of remission. This has significant adverse effects including severe infection and amenorrhea. In addition, although cyclophosphamide induces remission, long-term mortality does not seem to be altered. Mycophenolate mofetil (MMF) is an immunosuppressive agent originally used in solid organ transplantation, which has been compared with cyclophosphamide in trials for lupus nephritis. Randomized trials with MMF have been relatively small, although pooled data seem to suggest that it is at least as effective as cyclophosphamide in inducing remission. In addition, MMF has also been associated with a reduced risk of infection and amenorrhea, although this finding is not universal. MMF appears to be associated with more diarrhea compared with cyclophosphamide. MMF is likely to be a useful treatment for lupus nephritis, although available trial data are limited due to the small size of previous studies. A large trial (the Aspreva Lupus Management Study) is currently underway to attempt to establish the place of MMF in treatment of lupus nephritis.

Mycophenolate mofetil in the treatment of systemic lupus erythematosus

Mycophenolate mofetil (MMF) is an immunosuppressive agent that has been shown to be effective in transplant patients. It is also efficacious in the management of lupus nephritis and useful in the treatment of autoimmune conditions because its mechanisms of action target T- and B- lymphocytes, leading to suppression of the cell-mediated immune response and antibody formation. MMF has been used successfully to treat immune-mediated conditions like myasthenia gravis, autoimmune hepatitis and immune cytopenias. However, the conditions for its optimal use for non-renal manifestations (e.g., hematological, neuropsychiatric, myocardial, pulmonary or cutaneous symptoms) in lupus patients are unclear. There have yet to be any randomized, controlled trials to guide the optimal dose and duration of MMF treatment in such situations. MMF is well tolerated and safe to use, although there are reports of serious adverse effects including urticaria, myopathy, Epstein-Barr virus-associated B-cell lymphoma, cytomegalovirus infection and disseminated varicella zoster infection. Immunosuppressive treatment with MMF and supportive care over the past few decades have led to improved clinical outcomes in patients with severe lupus nephritis. A favorable long-term prognosis can be ensured provided that effective treatment is instituted early, before irreversible renal parenchymal damage occurs. Another area of concern for patients is the increased cost of long-term MMF use.

Immunosuppressive drugs have different effect on B lymphocyte subsets and IgM antibody production in immunized BALB/c mice

Infections are frequently associated with immunosuppressive therapy currently used to prevent organ rejection or treat autoimmune diseases. Such drugs suppress antibody production despite having different mechanisms of action. Antibodies are produced by a non-homogenous population of B lymphocyte subsets. B-1 cells produce natural antibodies and protect immediately after infection, while B2 cells produce antigen-specific IgM antibodies in a later response to infection. To understand how the immunosuppressive drugs affect antibody production by B cell populations, we immunized BALB/c mice with different antigens followed by administration of various immunosuppressive drugs. B-1a and B-1b lymphocytes from spleens of sacrificed animals were analyzed by flow cytometry, natural and antigen -specific IgG and IgM antibodies were determined by nephelometry and ELISA assays. Results showed that prednisone (PDN), cyclophosphamide (CYC), methotrexate (MTX), mycophenolate mofetil (MMF) and azathioprine (AZA) decreased more than 60% of B-1a lymphocytes while cyclosporine (CsA) had little effect. Three drugs PDN, AZA and CYC suppressed the B-2 cells on day 30, while MTX affected this subpopulation early on day 5. Antigen-specific IgM antibodies were dramatically suppressed after 15 days of immunization in animals receiving PDN, CYC or AZA, while MMF, CsA and MTX showed little effect. Natural antibodies were equally decreased in all animals regardless of the specific drug used in treatment. These results will help to choose single or combinations of immunosuppressive drugs in the clinical setting.

Rosiglitazone decreases blood pressure and renal injury in a female mouse model of systemic lupus erythematosus

Women with systemic lupus erythematosus (SLE) exhibit a high prevalence of hypertension and renal injury. Rosiglitazone (Rosi), a peroxisome proliferator activator receptor gamma (PPARgamma) agonist, has renal protective and antihypertensive effects. We tested whether Rosi ameliorates hypertension and renal injury in a female mouse model of SLE (NZBWF1). Thirty-week-old SLE and control (NZW/LacJ) mice (n > or = 6/group) were fed Rosi (5 mg.kg(-1).day(-1) in standard chow) or standard chow for 4 wk. SLE mice had increased blood pressure (BP in mmHg) compared with controls (139 +/- 4 vs. 111 +/- 4, P < 0.05). Rosi treatment lowered BP in SLE mice (127 +/- 4, P < 0.05) but not in controls (111 +/- 4). Urinary albumin (mug/mg creatinine) was increased in SLE mice compared with controls (12,396 +/- 6,525 vs. 50 +/- 6) and reduced with Rosi treatment (148 +/- 117). Glomerulosclerosis (% of glomeruli with sclerosis) was reduced in Rosi-treated SLE mice (4.2 +/- 1.6 vs. 0.4 +/- 0.3, P < 0.05). Renal monocyte/macrophage numbers (cell number/1,320 points counted) were reduced in SLE mice treated with Rosi (32.6 +/- 11.0 vs. 10.6 +/- 3.6, P < 0.05) but unchanged in controls (3.7 +/- 1.6 vs. 3.7 +/- 2.0). Renal osteopontin expression, a cytokine-regulating macrophage recruitment, was reduced in Rosi-treated SLE mice. Urinary endothelin (in pg/mg creatinine) was increased in SLE mice compared with controls (1.9 +/- 0.59 vs. 0.6 +/- 0.04, P < 0.05) and reduced in SLE mice treated with Rosi (0.8 +/- 0.11, P < 0.05). PPARgamma protein expression in the renal cortex was significantly lower in SLE mice compared with controls and was unaffected by Rosi. These data suggest that Rosi may be an important therapeutic option for the treatment of SLE hypertension and renal injury.

Anti-Ccl2 Spiegelmer permits 75% dose reduction of cyclophosphamide to control diffuse proliferative lupus nephritis and pneumonitis in MRL-Fas(lpr) mice

Cyclophosphamide (CYC) can control diffuse proliferative lupus nephritis (DPLN) by potent immunosuppression but remains associated with serious and life-threatening complications. Drugs that specifically target mediators of DPLN may help to reduce CYC dose and side effects. Monocyte chemoattractant protein (MCP-1)/CCL2 mediates monocyte and T cell recruitment in DPLN and Ccl2-specific l-enantiomeric RNA Spiegelmer mNOX-E36 neutralizes the biological effects of murine Ccl2 in vitro and in vivo. We injected MRL(lpr/lpr) mice with DPLN from 14 weeks of age with vehicle, weekly 30 mg/kg CYC (full dose), monthly 30 mg/kg CYC (one-fourth full dose), pegylated control Spiegelmer, pegylated anti-Ccl2 Spiegelmer (3/week), pegylated anti-Ccl2 Spiegelmer plus CYC one-fourth full dose and mycophenolate mofetil. At week 24, DPLN and autoimmune lung injury were virtually abolished with CYC full dose but not with CYC one-fourth full dose. The CYC one-fourth full dose/Spiegelmer combination was equipotent to CYC full dose on kidney and lung injury. CD3(+)CD4(-)CD8(-) and CD3(+)CD4(+)CD25(+) T cells and serum interleukin-12p40 and tumor necrosis factor-alpha levels were all markedly affected by CYC full dose but not by CYC one-fourth full dose. No additive effects of anti-Ccl2 Spiegelmer were noted on bone marrow colony-forming unit-granulocyte macrophage counts and 7/4(high) monocyte counts, lymphoproliferation, and spleen T cell depletion. In summary, anti-Ccl2 Spiegelmer permits 75% dose reduction of CYC for controlling DPLN and pneumonitis in MRL-Fas(lpr) mice, sparing suppressive effects of full-dose CYC on myelosuppression and T cell depletion. We propose anti-Ccl2 Spiegelmer therapy as a novel strategy to reduce CYC toxicity in the treatment of severe lupus.

Stimulation of lymphocyte responses by angiotensin II promotes kidney injury in hypertension

Activation of the renin-angiotensin system contributes to the progression of chronic kidney disease. Based on the known cellular effects of ANG II to promote inflammation, we posited that stimulation of lymphocyte responses by ANG II might contribute to the pathogenesis of hypertensive kidney injury. We therefore examined the effects of the immunosuppressive agent mycophenolate mofetil (MMF) on the course of hypertension and kidney disease induced by chronic infusion of ANG II in 129/SvEv mice. Although it had no effect on the severity of hypertension or cardiac hypertrophy, treatment with MMF significantly reduced albuminuria and ameliorated kidney injury, decreasing glomerulosclerosis and reducing lymphocyte infiltration into the renal interstitium. Attenuation of renal pathology with MMF was associated with reduced expression of mRNAs for the proinflammatory cytokines interferon-gamma and tumor necrosis factor-alpha and the profibrotic cytokine transforming growth factor-beta. As infiltration of the kidney by T lymphocytes was a prominent feature of ANG II-dependent renal injury, we carried out experiments examining the effects of ANG II on lymphocytes in vitro. We find that exposure of splenic lymphocytes to ANG II causes prominent rearrangements of the actin cytoskeleton. These actions require the activity of Rho kinase. Thus, ANG II exaggerates hypertensive kidney injury by stimulating lymphocyte responses. These proinflammatory actions of ANG II seem to have a proclivity for inducing kidney injury while having negligible actions in the pathogenesis of cardiac hypertrophy.

Immune tolerance induction to enzyme-replacement therapy by co-administration of short-term, low-dose methotrexate in a murine Pompe disease model

Clinical investigations of recombinant human acid alpha-glucosidase for the treatment of Pompe disease often reveal the appearance of therapy-specific antibodies. These antibodies could potentially interfere with recombinant human acid alpha-glucosidase efficacy and induce immunological consequences. Several immunosuppressive agents, including methotrexate, mycophenolate mofetil and cyclosporin A with azathioprine, were evaluated for their potential to induce immune tolerance to recombinant human acid alpha-glucosidase. Methotrexate was the only agent that reduced recombinant human acid alpha-glucosidase-specific antibody responses in acid alpha-glucosidase knock-out mice. A 3-week, low-dose methotrexate regimen controlled recombinant human acid alpha-glucosidase-specific antibody levels throughout 8 months of weekly recombinant human acid alpha-glucosidase treatment. The success of this methotrexate regimen appears to require methotrexate administration within the first 24 h of recombinant human acid alpha-glucosidase treatment. In an attempt to understand the benefit of methotrexate within the first day of recombinant human acid alpha-glucosidase administration, the immune response 24 h following intravenous recombinant human acid alpha-glucosidase treatment was investigated. A consistent expansion of peritoneal B1 B cells was observed. Control over this B1 B cell response may be part of the complex mechanism of action of methotrexate-induced immune tolerance.

Detection of eight antibodies in cancer patients’ sera against proteins derived from the adenocarcinoma A549 cell line using proteomics-based analysis

To screen cancer for specific autoantibodies, we applied the approach established by Brichory et al., who reported annexins I and II as specific antigens. Solubilized proteins from a cancer cell line (A549) were separated using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), followed by Western blotting (WB) analysis, in which the sera of individual patients were tested for primary antibodies. We found 11 positive spots on PVDF membrane using a WB/enhanced chemiluminescence detection Kit, and identified eight proteins, such as alpha-enolase, inosine-5'-monophosphate dehydrogenase, aldehyde dehydrogenase, 3-phosphoglycerate dehydrogenase, 3-oxoacid CoA transferase, chaperonin, peroxiredoxin 6 and triosephosphate isomerase, that reacted with these antibodies in patients' sera using MALDI-TOF/TOF. All eight antibodies were not detected in the sera derived from lung tuberculosis and healthy controls.

New therapies and preventive strategies to treat and minimize damage in lupus

Systemic lupus erythematosus is a complex disease characterized by a loss of immune tolerance leading to autoantibody production, immune complex deposition in target organs, and resultant tissue damage. There are currently only three medications approved for the treatment of lupus; hydroxychloroquine, aspirin, and prednisone. This limited spectrum of medications is contrasted by the dozen clinical trials in lupus underway or planned for the next 2 years. These new therapeutic agents hold promise for being more effective with fewer side effects than the current available agents. Increased awareness of co-morbid diseases in lupus is also leading to new approaches for the prevention of "disease damage" in lupus.

Randomized controlled trial of pulse intravenous cyclophosphamide versus mycophenolate mofetil in the induction therapy of proliferative lupus nephritis

BACKGROUND

The aim of the present study was to evaluate the efficacy of mycophenolate mofetil in the induction therapy of proliferative lupus nephritis.

METHODS

Forty-four patients from eight centres with newly diagnosed lupus nephritis World Health Organization class III or IV were randomly assigned to either mycophenolate mofetil (MMF) 2 g/day for 6 months or intravenous cyclophosphamide (IVC) 0.75-1 g/m(2) monthly for 6 months in addition to corticosteroids.

RESULTS

Remission occurred in 13 out of 25 patients (52%) in the IVC group and 11 out of 19 patients (58%) in the MMF group (P = 0.70). There were 12% in the IVC group and 26% in the MMF group that achieved complete remission (P = 0.22). Improvements in haemoglobin, the erythrocyte sedimentation rate, serum albumin, serum complement, proteinuria, urinary activity, renal function and the Systemic Lupus Erythematosus Disease Activity Index score were similar in both groups. Twenty-four follow-up renal biopsies at the end of therapy showed a significant reduction in the activity score in both groups. The chronicity index increased in both groups but was only significant in the IVC group. Adverse events were similar. Major infections occurred in three patients in each group. There was no difference in gastrointestinal side-effects.

CONCLUSIONS

MMF in combination with corticosteroids is an effective induction therapy for moderately severe proliferative lupus nephritis.

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.

Mycophenolate mofetil in animal models of autoimmune disease

Mycofenolate mofetil (MMF-Cellcept) is an immunomodulatory drug utilized extensively in transplant medicine. The efficacy of regimes including Cellcept in preventing allograft rejection, and in the treatment of rejection, is now firmly established. The immunosuppressive actions of this drug enabled the investigation for the beneficial effects in autoimmune diseases. We review the evidence for the contribution of MMF in autoimmunity in animal models of systemic lupus erythematosus (SLE), mercury induced autoimmune glomerulonephritis, diabetes mellitus, experimental autoimmune uveoretinitis, and experimental allergic encephalitis. MMF has an influence on the T and B cell pathways. It is immunosuppressive and anti-inflammatory.

Mycophenolate mofetil in lupus nephritis

There is an increasing body of literature suggesting the efficacy and tolerability of mycophenolate mofetil (MMF) for the treatment of lupus nephritis. The rationale for its use is based upon its successful profile as an immunosuppressive agent for prevention of allograft rejection, as well as studies in murine models of lupus which have reported improved renal function and animal survival compared to placebo. This report reviews the data regarding MMF therapy in murine lupus models, and describes the initial anecdotal experience with MMF in human lupus, especially in patients with glomerulonephritis who were unresponsive to corticosteroids and cyclophosphamide, or who had unacceptable toxicity on this standard of care regimen. The results of several nonblinded, controlled clinical trials are also described, in which MMF was compared to intravenous or oral cyclophosphamide in patients with lupus nephritis. MMF was found to be well tolerated, with most studies showing fewer infections than that associated with cyclophosphamide. Efficacy of MMF was at least equivalent to cyclophosphamide, and therefore appears to provide an alternative as a standard of care for induction and maintenance treatment of lupus nephritis.

New perspectives in treatment of glomerulonephritis

In chronic glomerulonephritis (GN) the development of the tissue damage and progression to fibrosis is related to the individual immune response which brings about excessive inflammation, failure to activate regression and glomerular repair and excessive fibrogenic activity. Therefore, the present standard treatment of GN has two aims, to fight the acute inflammation and to inhibit the progressive renal fibrosis. New avenues in the anti-inflammatory and immunosuppressive treatment of the active phase of glomerular diseases include the use of drugs proven to be of value in organ transplantation (mycophenolate mofetil, rapamycin or anti-immune adhesion and anti-co-stimulatory molecules). Interest has recently focused on anti-inflammatory cytokines (monoclonal antibodies, peptidic antagonists or anti-sense oligonucleotides against TNF-alpha, anti-PDGF-beta, anti-TGF-beta and cytokine receptor antagonists) and anti-inflammatory natural cytokines (such as IL4, IL10, IL13 or low doses of TGFbeta). Other drugs may act by depleting B cells (such as anti-CD20 monoclonal antibody) or on several immune pathways, such as thalidomide or anti-cyclooxygenase 2. Several anti-sclerogenic drugs are already used for treatment of the chronic phase of glomerular diseases, such as antagonists of angiotensin II, statins and antioxidants. Other drugs are still experimental, including endothelin receptor antagonists and neutral endopeptidase or vasopeptidase inhibitors and other drugs operating on extracellular matrix accumulation/degradation mechanisms, e.g., pirfenidone. There are extremely interesting developments concerning activators of endogenous anti-inflammatory mechanisms, such as those regulated by peroxisome proliferator activated receptors. There is a need for successful treatment of chronic GN in childhood. This short review of the most promising new drugs shows there is reason to believe that the next decade will provide exciting new tools for the treatment of these diseases in children.

Modulation of autoantibody production by mycophenolate mofetil: effects on the development of SLE in (NZB x NZW)F1 mice

BACKGROUND

Mycophenolate mofetil (MMF) has been successfully used to improve or prevent the development of systemic lupus erythematosus (SLE) in both humans and in several lupus-prone mice. In the present study, we evaluated mechanisms through which MMF may exert its therapeutic effect on the development of systemic autoimmunity.

METHODS

(NZBxNZW)F(1) female mice were continuously treated with 100 mg/kg/day (high dose) or 30 mg/kg/day (low dose) MMF beginning at 3 months of age. The development of an autoimmune syndrome was evaluated by measuring immunoglobulin (Ig) isotypes of autoantibodies and their levels, as well as by evaluating immunopathological kidney abnormalities and mortality curves.

RESULTS

At both doses, MMF efficiently modulated the development of SLE. Although the higher dose of MMF directly inhibited the production of autoantibodies, 30 mg/kg/day MMF promoted qualitative but not quantitative changes in autoantibodies in (NZB x NZW)F(1) female mice. These qualitative changes were manifested as a selective reduction in total or antigen-specific IgG2a antibody levels.

CONCLUSIONS

The mechanisms through which MMF controls the development of SLE in (NZB x NZW)F(1) females is highly dependent upon immunosuppressor dose. Interestingly, lower dose MMF selectively reduced IgG2a antibody levels, suggesting that this dose may modulate T(H1) CD4+ activity.

Newer drugs for the treatment of lupus nephritis

This article first reviews the current treatment of lupus nephritis, with a focus on the most serious forms, that is, the proliferative subtypes. Current standards for treatment have been developed empirically. Corticosteroids form the basis of all regimens. Cyclophosphamide given intravenously for prolonged periods is the current gold standard. Azathioprine can be regarded as an effective drug for maintenance treatment of lupus nephritis. Studies on its efficacy in schedules for remission induction are in progress. It has been learned from studies on 'conventional' immunosuppression that randomised, clinical trials should comprise large numbers of patients and a follow-up of many years to elucidate differences between effective strategies. These requirements are not met by any of the 'new' treatments we discuss in this review. There is only limited experience in patients with lupus nephritis with drugs that are currently used for immunosuppression in other autoimmune diseases, such as methotrexate, cyclosporin and high-dose intravenous gammaglobulins, nor with new immunosuppressive drugs that have been developed for immunosuppression in organ transplantation (mycophenolate mofetil, tacrolimus, fludarabine and cladribine). Hormonal therapy with the weak androgen prasterone (dehydroepiandrosterone; DHEA) has no role in treatment of active lupus nephritis. There are interesting experiences with agents that have evolved from progress in immunobiology and in our understanding of immunological processes. These modalities enable more specific immunosuppression and include monoclonal antibodies directed at immune cells, cytokines and components of the complement system, constructs developed to induce tolerance in pathogenic B cells, and gene therapy. Finally, we review data on autologous bone marrow transplantation in patients with systemic lupus erythematosus. We conclude that some strategies (like mycophenolate mofetil) are good candidates for further investigation in large-scale, prospective, randomised trials with prolonged follow-up (which are almost by definition hard to perform). Most new biological agents still are in a pre-clinical phase.

Effect of mycophenolate mofetil on severity of nephritis and nitric oxide production in lupus-prone MRL/lpr mice

Mycophenolate mofetil (MMF), an immunosuppressive drug commonly used in organ transplantation, is increasingly being used to treat autoimmune diseases including systemic lupus erythematosus (SLE). Excessive production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of lupus nephritis. We evaluated the effect of MMF on the severity of nephritis and the production of NO in lupus-prone MRL/lpr mice. Eight-week-old female MRL/lpr mice (n = 20) were treated with MMF (100 mg/kg/day) by oral gavage for 12 weeks. Control mice (n = 20) received vehicle on the same schedule. The mice were killed after 12 weeks of treatment. Treatment with MMF significantly decreased the amount of proteinuria, prolonged survival and reduced the histological severity of glomerulonephritis. Urinary nitrite/nitrate excretion in the MMF-treated mice was significantly reduced during the first 8 weeks of treatment. However, by the end of the 12 weeks' treatment period, there was no significant difference between vehicle and MMF-treated mice in terms of urinary nitrite/nitrate excretion, intra-renal production of NO, expression of iNOS protein and induction of iNOS mRNA. We conclude that MMF is effective in attenuating the severity of nephritis in MRL/lpr mice. The beneficial effects of MMF on lupus nephritis during the early phase of the disease might be partly attributed to the inhibition of NO production. The inhibitory effect of MMF on NO production diminishes as the disease progresses. MMF probably has additional, as yet undefined mode of actions to fully account for its beneficial effects on lupus nephritis.

Mycophenolic acid inhibits inosine 5'-monophosphate dehydrogenase and suppresses immunoglobulin and cytokine production of B cells

Mycophenolic acid (MPA) reversibly inhibits inosine 5'-monophosphate dehydrogenase (IMPDH), an enzyme involved in the de novo synthesis of guanine nucleotides. Previously, mycophenolate mofetil (MMF), the pro-drug of MPA, was shown to exert beneficial effects on the systemic lupus erythematosus (SLE)-like disease in MRLlpr/lpr mice. In this study, MPA's immunomodulating effects in vitro on the B cell hybridoma MAR 18.5 were investigated. The cells were exposed for MPA at either 1 or 10 microM for 24 h, and the levels of immunoglobulins, cytokines and lactate dehydrogensase in supernatants were measured. The frequency of immunoglobulin producing cells and the proliferation and viability of the cells was also investigated. MPA exposure reduced the frequency of immunoglobulin producing cells, decreased the levels of immunoglobulins and cytokines in the supernatants, and decreased the cell proliferation. MPA was slightly cytotoxic as indicated by increased lactate dehydrogenase (LDH) levels and reduced viability. All MPA-induced effects were totally reversed by the addition of guanosine to the cultures. Thus, since activated B lymphocytes play a central role in lupus and our results show that B cells are targets for MPA, we propose that direct effects on B cells may be an important mechanism for the ameliorating effects of MMF in SLE.

Mycophenolate mofetil: new applications for this immunosuppressant

OBJECTIVES

This article should familiarize the reader with the pharmacokinetics, mechanisms of action, potential toxicities, and current and future applications of mycophenolate mofetil.

DATA SOURCES

The current medical literature.

RESULTS

Mycophenolate mofetil is an immunosuppressive agent that has been used for transplant recipients. More recently, this agent has been used to treat several inflammatory conditions.

CONCLUSIONS

Mycophenolate mofetil has the potential to be a useful agent in the treatment of several inflammatory conditions, including systemic lupus erythematosus.

Mycophenolate mofetil in lupus glomerulonephritis

The optimal treatment of severe lupus nephritis is unclear. Regimens consisting of steroid and cyclophosphamide (CYC) appear to be most effective. However, up to 15% of patients are refractory to CYC treatment, and 30% to 50% of patients still develop end-stage renal disease. Moreover, infection and gonadal toxicity are major concerns of CYC use in patients of the reproductive age. More effective, but less toxic, regimens are needed. Mycophenolate mofetil (MMF) is a new immunosuppressive agent that selectively inhibits activated lymphocytes and renal mesangial cells. Experience with MMF in solid-organ transplantation has shown the safety of this drug and its superiority over azathioprine (AZA) in the prevention of acute graft rejection. Data from experimental models of immune-mediated glomerulonephritis, particularly lupus nephritis, have shown that MMF ameliorates autoimmune phenomena, retards renal damage, and improves outcome. Although the use of MMF in lupus nephritis is still in its preliminary stage, uncontrolled experience has confirmed its efficacy in patients with serious disease recalcitrant to conventional cytotoxic agents. Controlled studies, albeit small and lacking statistical power, have shown that MMF is as effective as CYC in the induction of renal remission in the short term. With the current dosage used in systemic lupus erythematosus, MMF appears to be well tolerated, with no serious toxicities reported. Significantly less ovarian toxicity compared with CYC is particularly attractive for the consideration of MMF in lupus nephritis. However, the lack of long-term efficacy data and comparative studies with standard CYC regimens is the major deterrent for the first-line use of MMF in high-risk patients at this juncture.

Effects of mycophenolate mofetil in mercury-induced autoimmune nephritis

Mycophenolate mofetil (MMF) is a new immunosuppressive drug whose active metabolite, mycophenolic acid (MPA), blocks the action of inosine monophosphate dehydrogenase, resulting in the inhibition of the novo purine synthesis. Thus, MPA has an antiproliferative effect on T and B lymphocytes and also inhibits the glycosylation of cell surface adhesion proteins involved in cell-cell contact and in the recruitment of circulating leukocytes to sites of tissue damage and inflammation. In this study, the effect of MMF in the mercury model of nephritis was examined. Repeated exposure to HgCl(2) induces an autoreactive Th2 cell subset-inducing polyclonal B cell activation in the Brown Norway (BN) rat. This leads to the development of an autoimmune syndrome characterized by synthesis of autoantibodies (mainly anti-glomerular basement membrane [GBM] Abs) with glomerular linear deposits of IgG, proteinuria, and tubulointerstitial nephritis. Results show that MMF has a preventive effect on mercury-induced disease as it blocks anti-GBM Ab synthesis, thus avoiding glomerular IgG deposits and proteinuria and the development of interstitial nephritis. However, the therapeutic effect of MMF seems to be restricted to its antiinflammatory properties blocking the extravasation of circulating leukocytes to renal interstitium by interfering with the very late activation antigen 4/vascular cell adhesion molecule-1 (VCAM-1) cell adhesion pathway. Also, MMF administration to mercury-injected rats reduces the secretion of the proinflammatory cytokine tumor necrosis factor-alpha. These findings confirm that MMF has a strong effect on the primary immune response in this model. Nevertheless, when the disease is in progress, MMF acts exclusively on the inflammatory response. MMF could be useful in the treatment of diseases associated with renal inflammation.

Mycophenolic acid inhibits inosine 5'-monophosphate dehydrogenase and suppresses production of pro-inflammatory cytokines, nitric oxide, and LDH in macrophages

Mycophenolic acid (MPA) inhibits reversibly inosine 5(')-monophosphate dehydrogenase, an enzyme involved in the de novo synthesis of guanine nucleotides. Previously, mycophenolate mofetil (MMF), the pro-drug of MPA, was shown to exert beneficial effects on the systemic lupus erythematosus (SLE)-like disease in MRLlpr/lpr mice. In this study MPA's immunomodulating effects in vitro on the murine macrophage cell line IC-21 were investigated. The cells were exposed to MPA together with lipopolysaccharide and IFN-gamma. Cytokine, NO(2)(-), and lactate dehydrogenase levels in supernatants and cell lysates were analysed as well as the proliferation of IC-21 cells. MPA exposure reduced the total levels of all molecules investigated and suppressed the proliferation. All MPA-induced effects were reversed by the addition of guanosine to the cultures. Since macrophages play a role in lupus nephritis, our results indicate that modulation of macrophages may be involved in the ameliorating effects of MMF in SLE.

LF15-0195 prevents the induction and inhibits the progression of rat anti-GBM disease

BACKGROUND

LF15-0195 is a novel immunosuppressant that is currently in phase II clinical trials for the treatment of vasculitis. This study examined whether LF15-0195 could suppress the induction and progression of rat anti-glomerular basement membrane (anti-GBM) glomerulonephritis.

METHODS

Rapidly progressive glomerulonephritis was induced in primed rats by the administration of anti-GBM serum. In the first experiment, LF15-0195 was given daily by subcutaneous injection (days 0 to 14) to treat the induction of anti-GBM disease analyzed at day 14. In a second experiment, rats received LF15-0195 as an intervention treatment from days 7 to 28 (continuous therapy) or days 7 to 12 (pulse therapy) to treat the progression of disease assessed at day 28.

RESULTS

Continuous LF15-0195 treatment during the induction of anti-GBM disease (experiment 1) prevented proteinuria and loss of renal function, and markedly reduced histological kidney lesions and renal fibrosis. LF15-0195 also reduced kidney leukocyte infiltrate, urine excretion of interleukin-1beta (IL-1beta) and transforming growth factor-beta (TGF-beta), and the serum antibody response, but not kidney deposition of Ig and C3. When LF15-0195 treatment was initiated at day 7, both continuous and pulse therapy partially inhibited disease progression by suppressing the loss of renal function, interstitial macrophage and T-cell accumulation, tubular cell proliferation, and renal fibrosis.

CONCLUSION

LF15-0195 prevents the induction and suppresses the progression of rat anti-GBM disease through multiple mechanisms of action, suggesting that this drug may have significant therapeutic potential in human glomerulonephritis. The similar efficacy of continuous and pulse intervention treatment in this model indicates that short-term LF15-0195 treatment may achieve optimal benefit without prolonged bone marrow suppression.

Effect of mycophenolate mofetil on the progression of adriamycin nephropathy

In order to assess the effects of mycophenolate mofetil (MMF) on the development of adriamycin-induced nephropathy, the development of this nephropathy in rats treated with MMF was compared to that in non-treated animals (group ADR + V) over 28 weeks. At weeks 8, 16 and 20, 24-h proteinuria of the treated group statistically differed from that of the non-treated group. However, no significant difference in proteinuria was observed thereafter between the groups. At the end of the experiment, there was no significant difference between both groups regarding the frequency of glomerular lesion (Group ADR + V: Md = 35%, P25 = 20%, P75 = 68%; Group ADR + MMF: Md = 27%, P25 = 9.5%, P75 = 54%); tubulointerstitial lesion index (Group ADR + V: Md = 7, P25 = 1.5, P75 = 9; Group ADR + MMF: Md = 8, P25 = 2, P75 = 9); glomerulosclerosis area (group ADR + V = 2779 microm2, P25 = 751.8 microm2, P75 = 3115 microm2; Group ADR + MMF = 1147 microm2, P25 = 3969.7 microm2, P75 = 1560 microm2); and, interstitial fibrosis area (Group ADR + V: Md = 218200 microm2, P25 = 78670 microm2, P75 = 282700 microm2 group ADR + MMF: Md = 136000, P25 = 25010, P75 = 255800 microm2). In conclusion, MMF caused a temporary reduction in proteinuria but did not change the severity of the renal lesion observed after 28 weeks.

Treatment of systemic lupus erythematosus with mycophenolate mofetil

Mycophenolate mofetil is an immunosuppressive drug that is of established efficacy in renal transplantation. It inhibits the de novo pathway of purine synthesis and therefore lymphocyte proliferation. Mycophenylate mofetil has been shown to ameliorate the severity of renal injury in murine models of lupus nephritis. Recent studies suggest that it may also be effective in the treatment of patients with lupus nephritis when used in conjunction with steroids. These observations need to be confirmed in adequately sized randomised-controlled studies.

Mycophenolate mofetil reduces renal cortical inducible nitric oxide synthase mRNA expression and diminishes glomerulosclerosis in MRL/lpr mice

Overexpression of inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of lupus glomerulonephritis. Mycophenolate mofetil (MMF), a novel immunosuppressive agent, is currently used in organ transplantation and under evaluation for treatment of autoimmune disorders. Mycophenolic acid, the active metabolite of MMF, has been shown to suppress cytokine-induced nitric oxide production in vitro. The aim of this study was to evaluate the effect of MMF on the expression of renal cortical iNOS mRNA and protection against glomerulonephritis in MRL/lpr mice. Three-month-old MRL/lpr mice (n = 6) displaying clinical symptoms of glomerulonephritis were treated for 3 months with MMF (90 mg/kg/day) dissolved in a vehicle. Controls were age- and sex-matched mice (n = 6) that received the vehicle alone. By reverse-transcription competitive polymerase chain reaction, we found that the renal cortical iNOS/beta-actin mRNA ratio was reduced by 30.8% (P <.05) in MMF-treated mice. Furthermore, MMF significantly reduced urinary nitrite production and degree of glomerulosclerosis. The glomerular volume was reduced by 17.5% (P <.001). Proteinuria was also significantly reduced in the MMF-treated group. However, by electrophoretic mobility shift assay, the nuclear binding of nuclear factor-kappaB (NF-kappaB) was not affected by MMF treatment. We conclude that in addition to its immunosuppressive action, MMF may reduce renal cortical iNOS mRNA expression and diminish glomerulosclerosis in MRL/lpr mice independent of modulation of the NF-kappaB pathway.

Inosine monophosphate dehydrogenase (IMPDH) inhibition in vitro suppresses lymphocyte proliferation and the production of immunoglobulins, autoantibodies and cytokines in splenocytes from MRLlpr/lpr mice

The aim of this study was to evaluate the effects of the immunomodulating drug mycophenolic acid (MPA) on splenocytes in an animal model of systemic lupus erythematosus (SLE), using MRLlpr/lpr mice. MPA reversibly inhibits inosine 5'-monophosphate dehydrogenase, an enzyme involved in the de novo guanosine synthesis. Splenocytes were treated with MPA (at 1 or 10 microM), and stimulated with either lipopolysaccharide (LPS; 10 microg/ml) or concanavalin A (ConA; 1.25 microg/ml). In blocking experiments, guanosine (100 microM) was added to the cultures to inhibit the effects of MPA. Lymphocyte proliferation, enumeration of immunoglobulin producing cells (using ELISPOT) and quantification of anti-double-stranded (ds) DNA antibodies, IFN-gamma and IL-10 (by ELISA) in supernatants were performed. In addition, cell viability was evaluated using propidium iodide and flow cytometry. We found that MPA-treated splenocytes had dramatically decreased mitogen-induced proliferation and number of immunoglobulin producing cells, down-regulated production of IFN-gamma, IL-10 and IgM anti-dsDNA antibodies. The viability of MPA-treated cells was also decreased. All of the effect modulated by MPA could be neutralized by the addition of guanosine. We conclude that MPA has potent immunomodulating effects on both B and T lymphocytes, modulating not only proliferation, but also the production of cytokines, immunoglobulins and autoantibodies.

Efficacy of mycophenolate mofetil in patients with diffuse proliferative lupus nephritis. Hong Kong-Guangzhou Nephrology Study Group

BACKGROUND

The combination of cyclophosphamide and prednisolone is effective for the treatment of severe lupus nephritis but has serious adverse effects. Whether mycophenolate mofetil can be substituted for cyclophosphamide is not known.

METHODS

In 42 patients with diffuse proliferative lupus nephritis we compared the efficacy and side effects of a regimen of prednisolone and mycophenolate mofetil given for 12 months with those of a regimen of prednisolone and cyclophosphamide given for 6 months, followed by prednisolone and azathioprine for 6 months. Complete remission was defined as a value for urinary protein excretion that was less than 0.3 g per 24 hours, with normal urinary sediment, a normal serum albumin concentration, and values for serum creatinine and creatinine clearance that were no more than 15 percent above the base-line values. Partial remission was defined as a value for urinary protein excretion that was between 0.3 and 2.9 g per 24 hours, with a serum albumin concentration of at least 30 g per liter.

RESULTS

Eighty-one percent of the 21 patients treated with mycophenolate mofetil and prednisolone (group 1) had a complete remission, and 14 percent had a partial remission, as compared with 76 percent and 14 percent, respectively, of the 21 patients treated with cyclophosphamide and prednisolone followed by azathioprine and prednisolone (group 2). The improvements in the degree of proteinuria and the serum albumin and creatinine concentrations were similar in the two groups. One patient in each group discontinued treatment because of side effects. Infections were noted in 19 percent of the patients in group 1 and in 33 percent of those in group 2 (P = 0.29). Other adverse effects occurred only in group 2; they included amenorrhea (in 23 percent of the patients), hair loss (19 percent), leukopenia (10 percent), and death (10 percent). The rates of relapse were 15 percent and 11 percent, respectively.

CONCLUSIONS

For the treatment of diffuse proliferative lupus nephritis, the combination of mycophenolate mofetil and prednisolone is as effective as a regimen of cyclophosphamide and prednisolone followed by azathioprine and prednisolone but is less toxic.

Novel approaches to therapy for systemic lupus erythematosus

Current therapies for systemic lupus erythematosus (SLE) are targeted at immunosuppression and at reducing inflammation. The current therapies are broad-spectrum and include steroids and cytotoxic agents that are counterbalanced by toxicity and side effects of the medications. Methotrexate can be utilized to reduce steroid requirements in mild to moderate SLE. Manipulation of the hormonal axis includes DHEA and bromocriptine. Mycophenolate mofetil is an immunosuppressive agent that is being investigated for SLE renal disease. Autologous stem cell transplantation or high-dose cyclophosphamide may be an option for severe refractory SLE. The aim of the future is to target therapies by altering specific known mechanisms of inflammation and autoimmunity. Although the inciting antigen is still unknown in SLE, it may be possible to alter the regulation of the immune response by targeted molecular therapy. Methods to do so would include manipulation of idiotypes, manipulation of second signal stimulation of the immune response, manipulation of cytokines, and the induction of tolerance by administration of blocking peptides. IVIg is an immunomodulator that has been successful in the treatment of SLE. Targeted molecular therapy is undergoing phase I trials with monoclonal anti-CD40L, a signaling inhibitor. Anti-CTLA4Ig, another signaling blocker, is presently being investigated for psoriasis, but may be a potential therapy for SLE. Finally, therapies may include the administration of peptides to induce tolerance.

Progress in the treatment of proliferative lupus nephritis

Lupus nephritis is often well developed at the time of diagnosis. High-dose corticosteroids are universally accepted as the initial approach to the control of severe inflammation in the kidney. Long-term disease control and the minimization of iatrogenic risk usually require adjunctive therapies that target the more fundamental immunoregulatory disturbances of lymphoid cells. Of the available cytotoxic drugs, cyclophosphamide is currently among the most effective, although it cannot be considered ideal in terms of efficacy or toxicity. New prospects for the treatment of proliferative lupus nephritis include novel immunosuppressive agents (e.g. mycophenolate, cyclosporine, fludarabine), combination chemotherapy (e.g. cyclophosphamide plus fludarabine), and sequential chemotherapy (e.g. cyclophosphamide-azathioprine), immunological reconstitution using intensive cytoreductive chemotherapy (with or without stem cell rescue), co-stimulatory molecule inhibition (e.g. humanized anti-CD154 monoclonal antibody, CTLA4-Ig). Gene therapy remains an attractive prospect, but its feasibility clearly depends on the further definition of lupus-promoting genes and the availability of methods to establish stable expression of disease-corrective genes in the appropriate lymphoid cells.

Mycophenolate mofetil ameliorates perivascular T lymphocyte inflammation and reduces the double-negative T cell population in SLE-prone MRLlpr/lpr mice

Effects on T lymphocyte mediated pathology, phenotypes, and functions in MRLlpr/lpr mice given mycophenolate mofetil (MMF) (100 mg/kg/day) via drinking water or controls given ip cyclophosphamide (CYC) injections (1.8 mg/mouse/week) or water were described. Both MMF and CYC treatment diminished kidney and large salivary gland perivascular cell infiltrates, reduced profoundly double-negative (DN) T cell frequencies, decreased total lymphocyte number in spleen, and increased in vitro proliferative response to Con A. IFN-gamma and IL-10 in supernatants from Con A stimulated spleen cells were augmented after MMF but not CYC treatment. MMF treatment increased whereas CYC reduced IL-12 in serum. Kidney expressions of IFN-gamma, IL-10, and IL-12 mRNA were unaffected by MMF but decreased by CYC. Our results demonstrate that MMF and CYC suppress perivascular T lymphocyte inflammation by reducing the DN T cell population and by amelioration of T cell function. The varying cytokine patterns suggest different mechanisms of the two drugs.

Non-transplant uses of mycophenolate mofetil

The immunosuppressive drug mycophenolate mofetil is a potential new treatment for autoimmune renal disease. In addition to its effects in modulating the autoimmune response, mycophenolate mofetil reduces adhesion molecule expression and delays the progression of renal failure. Data from experimental models of glomerulonephritis, especially of lupus nephritis, have demonstrated that mycophenolate mofetil reverses both inflammatory and autoimmune aspects of disease and influences outcome. As yet, clinical experience with mycophenolate mofetil remains anecdotal but provides a strong platform for the scientific evaluation of mycophenolate mofetil as a new therapeutic agent for these conditions in the future.