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

Cathepsin S Inhibition Suppresses Experimental Systemic Lupus Erythematosus-Associated Pulmonary Arterial Remodeling

Patients with systemic lupus erythematosus (SLE) associated with pulmonary arterial hypnertension (PAH) receive targeted therapy for PAH to decrease pulmonary arterial systolic pressure and significantly prolong their survival. Cysteine cathepsin proteases play critical roles in the progression of cardiovascular disease. Inhibition of cathepsin S (Cat S) has been shown to improve SLE and lupus nephritis. However, the effect of Cat S inhibitors on SLE-associated PAH (SLE-PAH) remains unclear, and there is no animal model for translational research on SLE-PAH. We hypothesized that the inhibition of Cat S may affect PAH development and arterial remodeling associated with SLE. A female animal model of SLE-PAH, female MRL/lpr (Lupus), was used to evaluate the role of pulmonary arterial remodeling in SLE. The key finding of the research work is the establishment of an animal model of SLE associated with PAH in female MRL/lpr mice that is able to evaluate pulmonary arterial remodeling starting from the age of 11 weeks to 15 weeks. Cat S protein level was identified as a marker of experimental SLE. Pulmonary hypertension in female MRL/lpr (Lupus) mice was treated by administering the selective Cat S inhibitor Millipore-219393, which stimulated peroxisome proliferator-activated receptor-gamma (PPARγ) in the lungs to inhibit Cat S expression and pulmonary arterial remodeling. Studies provide an animal model of female MRL/lpr (Lupus) associated with PAH and a deeper understanding of the pathogenesis of SLE-PAH. The results may define the role of cathepsin S in preventing progressive and fatal SLE-PAH and provide approaches for therapeutic interventions in SLE-PAH.

Are lupus animal models useful for understanding and developing new therapies for human SLE?

Systemic lupus erythematosus is a systemic autoimmune disease driven by a complex combination of genetic, environmental, and other immunoregulatory factors. The development of targeted therapies is complicated by heterogeneous clinical manifestations, varying organ involvement, and toxicity. Despite advances in understanding the mechanisms contributing to SLE, only one biologic drug, belimumab, is FDA-approved. The identification and development of potential therapies have largely been driven by studies in lupus animal models. Therefore, direct comparison of both the therapeutic and immunological findings in human and murine SLE studies is critical and can reveal important insights into indeed how useful and relevant are murine studies in SLE drug development. Studies involving belimumab, mycophenolate mofetil, abatacept, rituximab, and anti-interferon strategies generally demonstrated analogous findings in the attenuation of SLE manifestations and modulation of select immune cell populations in human and murine SLE. While further basic and translational studies are needed to identify SLE patient subsets likely to respond to particular therapeutic modalities and in dissecting complex mechanisms, we believe that despite some inherent weaknesses SLE mouse models will continue to be integral in developing targeted SLE therapies.

Inducible nitric oxide synthase and systemic lupus erythematosus: a systematic review and meta-analysis

Background

There is a growing body of evidences indicating iNOS has involved in the pathogenesis of SLE. However, the role of iNOS in SLE is inconsistency. This systematic review was designed to evaluate the association between iNOS and SLE.

Results

Six studies were included, reporting on a total of 277 patients with SLE. The meta-analysis showed that SLE patients had higher expression of iNOS at mRNA level than control subjects (SMD = 2.671, 95%CI = 0.446–4.897, z = 2.35, p = 0.019), and a similar trend was noted at the protein level (SMD = 3.602, 95%CI = 1.144–6.059, z = 2.87, p = 0.004) and positive rate of iNOS (OR = 9.515, 95%CI = 1.915–47.281, z = 2.76, p = 0.006) were significantly higher in SLE group compared with control group. No significant difference was observed on serum nitrite level between SLE patients and control subjects (SMD = 2.203, 95%CI = -0.386–4.793, z = 1.64, p = 0.095). The results did not modify from different sensitivity analysis, representing the robustness of this study. No significant publication bias was detected from Egger’s test.

Conclusions

There was a positive correlation between increasing iNOS and SLE. However, the source of iNOS is unknown. Besides NO pathway, other pathways also should be considered. More prospective random studies are needed in order to certify our results.

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.

Mycophenolate mofetil in nonlupus glomerulonephropathy

Mycophenolate mofetil (MMF) initially found widespread use in the immunoprophylaxis of rejection in organ transplantation. It has subsequently been used in lupus glomerulonephritis, where early studies have shown it to be effective in induction and maintenance therapy. The randomized studies have mostly studied small groups of patients and their conclusions do need to be confirmed in larger studies. MMF has also been used in small numbers of patients in a variety of nonlupus glomerulopathies, which have different underlying immunopathology as well as clinical course, including IgA nephropathy, membranous nephropathy, focal segmental glomerulosclerosis, membranoproliferative glomerulonephritis, hepatitis-C-associated glomerulonephritis and even Goodpasture's syndrome. In this article, we discuss its use in such nonlupus glomerular diseases.

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.

Aliskiren attenuates proteinuria in mice with lupus nephritis by a blood pressure-independent mechanism

This study revealed that low-dose aliskiren treatment could attenuate proteinuria by interrupting the renin-angiotensin system in mice with lupus nephritis, and the beneficial effect was beyond blood pressure control. An in and ex vivo fluorescence imaging (using a non-invasion in vivo imaging system) showed intense labeling of renin in the kidneys of female MRL/lpr mice. In the study, Alzet mini-osmotic pumps were implanted into 6-week-old female MRL/lpr mice. Pumps were filled with either phosphate-buffered saline or a solution of aliskiren dissolved in phosphate-buffered saline (20 mg/kg/day) and replaced at 28-day intervals. Mice were sacrificed at four and eight weeks. To label cells for DNA synthesis, bromodeoxyuridine (BrdU) (50 mg/kg) was injected intraperitoneally an hour prior to sacrifice. The level of renin inhibition was adequate, as aliskiren-treated mice demonstrated higher renal renin mRNA expression than controls (p < 0.05). Although there were no significant differences in the systolic blood pressure (control versus aliskiren-treated: 127.20 ± 4.44 mmHg versus 103.80 ± 7.40 mmHg, p > 0.05) and heart rate (control versus aliskiren-treated: 680.50 ± 11.71 versus 647.80 ± 13.90, p > 0.05) of both groups after eight weeks, there was significant reduction of inflammatory cytokines (transforming growth factor-beta1, regulated on activation normal T cell expressed, monocyte chemoattractant protein-1 and osteopontin, p < 0.05), reduction of innate immunity (toll-like receptor 7, p < 0.05), as well as a reduction of glomerular proliferation and inflammation (BrdU-, CD45-, CD3- and F4/80-positive glomerular cells, p < 0.01) after aliskiren infusion, which might translate into an improvement in proteinuria (control versus aliskiren-treated: 493.7 versus 843.7 mg/g, p < 0.01) or weight gain (control versus aliskiren-treated: 5.65 ± 1.61 versus 8.67 ± 0.97%, p < 0.05).

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.

Current and emerging strategies for the treatment and management of systemic lupus erythematosus based on molecular signatures of acute and chronic inflammation

Lupus is a chronic, systemic inflammatory condition in which eicosanoids, cytokines, nitric oxide (NO), a deranged immune system, and genetics play a significant role. Our studies revealed that an imbalance in the pro- and antioxidants and NO and an alteration in the metabolism of essential fatty acids exist in lupus. The current strategy of management includes administration of nonsteroidal anti-inflammatory drugs such as hydroxychloroquine and immunosuppressive drugs such as corticosteroids. Investigational drugs include the following: 1) belimumab, a fully human monoclonal antibody that specifically recognizes and inhibits the biological activity of B-lymphocyte stimulator, also known as B-cell-activation factor of the TNF family; 2) stem cell transplantation; 3) rituximab, a chimeric monoclonal antibody against CD20, which is primarily found on the surface of B-cells and can therefore destroy B-cells; and 4) IL-27, which has potent anti-inflammatory actions. Our studies showed that a regimen of corticosteroids and cyclophosphamide, and methods designed to enhance endothelial NO synthesis and augment antioxidant defenses, led to induction of long-lasting remission of the disease. These results suggest that methods designed to modulate molecular signatures of the disease process and suppress inflammation could be of significant benefit in lupus. Some of these strategies could be vagal nerve stimulation, glucose-insulin infusion, and administration of lipoxins, resolvins, protectins, and nitrolipids by themselves or their stable synthetic analogs that are known to suppress inflammation and help in the resolution and healing of the inflammation-induced damage. These strategies are likely to be useful not only in lupus but also in other conditions, such as rheumatoid arthritis, scleroderma, ischemia-reperfusion injury to the myocardium, ischemic heart disease, and sepsis.

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.

The biology of reactive intermediates in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune syndrome marked by autoantibody production. Innate immunity is essential to transform humoral autoimmunity into the clinical lupus phenotype. Nitric oxide (NO) is a membrane- permeable signaling molecule involved in a broad array of biologic processes through its ability to modify proteins, lipids, and DNA and alter their function and immunogenicity. The literature regarding mechanisms through which NO regulates inflammation and cell survival is filled with contradictory findings. However, the effects of NO on cellular processes depend on its concentration and its interaction with reactive oxygen. Understanding this interaction will be essential to determine mechanisms through which reactive intermediates induce cellular autoimmunity and contribute to a sustained innate immune response and organ damage in SLE.

Mycophenolate mofetil is associated with altered expression of chronic renal transplant histology

Mycophenolate mofetil (MMF) reduces acute rejection in controlled trials of kidney transplantation and is associated with better registry graft survival. Recent experimental studies have demonstrated additional antifibrotic properties of MMF, however, human histological data are lacking. We evaluated sequential prospective protocol kidney biopsies from two historical cohorts treated with cyclosporine (CSA)-based triple therapy including prednisolone and either MMF (n = 25) or azathioprine (AZA, n = 25). Biopsies (n = 360) were taken from euglycemic kidney-pancreas transplant recipients. Histology was independently assessed by the Banff schema and electron microscopic morphometry. MMF reduced acute rejection and OKT3 use (p < 0.05) compared with AZA. MMF therapy was associated with limited chronic interstitial fibrosis, striped fibrosis and periglomerular fibrosis (p < 0.05-0.001), mesangial matrix accumulation (p < 0.01), chronic glomerulopathy scores (p < 0.05) and glomerulosclerosis (p < 0.05). MMF was associated with delayed expression of CSA nephrotoxicity, reduced arteriolar hyalinosis, striped fibrosis and tubular microcalcification (p < 0.05-0.001). The beneficial effects of MMF remained in recipients without acute rejection. Retrospective analysis shows that MMF therapy was associated with substantially reduced fibrosis in the glomerular, microvascular and interstitial compartments, and a delayed expression of CSA nephrotoxicity. These outcomes may be due to a limitation of immune-mediated injury and suggest a direct effect of reduced fibrogenesis.

Combined MMF and insulin therapy prevents renal injury in experimental diabetic rats

Conventional therapies for diabetic mellitus are not effective in preventing the progression from early diabetic nephropathy (DN) to end-stage renal disease. The role of inflammation in the pathogenesis of DN has been implicated both clinically and experimentally, which provides an alternative therapeutic target for DN. Anti-inflammatory impact of mycophenolate mofetil (MMF) alone and in combination with insulin had been observed in a rat model of experimental DN. In this study, the diabetic rats were subjected to different treatments. Compared to control, the expression levels of CD68, NGF, and NF-kappaB p65, as determined immunohistochemically, were elevated in diabetic rats. Treatment with combined MMF/insulin is associated with a significant reduction in renal tissue of NGF and NF-kappaB p65 expression, macrophage infiltration. It also partially improved the renal function and attenuated renal hypertrophy at early stage of DN. CD68 was found to positively correlate with urinary albumin excretion and NGF. The combined use of MMF/insulin seemed to offer more protections in rats with experimental diabetic renal injury, and the protective effects of MMF might be due to its anti-inflammatory actions through inhibition of NF-kappaB activation and reduction of T cells and macrophage infiltration and/or other kidney chemokine productions.

The biology of nitric oxide and other reactive intermediates in systemic lupus erythematosus

Formation of reactive nitrogen and oxygen intermediates (RNI and ROI) is an essential part of the innate immune response. Markers of systemic RNI production are increased in the setting of systemic lupus erythematosus (SLE) activity. Several lines of evidence suggest mechanisms through which the activity of inducible nitric oxide synthase (iNOS) is pathogenic in SLE, including the ability of peroxynitrite (ONOO(-), a product of iNOS activity) to modify proteins, lipids, and DNA. These modifications can alter enzyme activity and may increase the immunogenicity of self antigens, leading to a break in immune tolerance. In humans, observational data suggest that overexpression of iNOS and increased production of ONOO(-) lead to glomerular and vascular pathology. Therapies designed to target iNOS activity or scavenge ROI and RNI are in development and may provide the means to reduce the pathogenic consequences of ROI and RNI in SLE.

Anti-inflammatory action of dietary fish oil and calorie restriction

Inflammation, inflammatory mediators, cyclooxygenase (COX)-2, and inducible nitric oxide (iNOS) are all influenced by age-related oxidative status. To investigate the effect of dietary fish oil (FO) and calorie restriction (CR) on oxidative stress-related inflammatory status with age, (NZB/NZW) F1 (B/W) mice were fed for 4 and 9 months either ad libitum or calorie-restricted (60% of ad libitum intake) diets containing 5% corn oil or 5% FO. We measured several key oxidative and inflammatory markers: TBARS, xanthine oxidase (XOD)-derived superoxide generation, and PGE2 and LTB4 production. Expressions of renal COX-1, COX-2, and iNOS mRNA were analyzed by RT-PCR; additionally, COX-2 protein was estimated by Western-blot method. Results show that FO intake and CR individually and together suppressed age-related increases in lipid peroxidation and superoxide generation. The inhibitory effects of dietary FO and CR were also found for iNOS expression, COX-2 expression, which subsequently led to the suppression of PGE2 and LTB4. We conclude that the beneficial effects of FO feeding and CR are synergistic in ameliorating the age-related nephritis of B/W mice by suppressing COX-2 and iNOS, reactive species generation, and pro-inflammatory mediators.

In situ glomerular expression of activated NF-kappaB in human lupus nephritis and other non-proliferative proteinuric glomerulopathy

Nuclear Factor-kappaB (NF-kappaB) has been suggested to play a role in the cellular and molecular mechanisms underlying glomerular injury. We investigated the potential role of NF-kappaB activation in the pathogenesis of glomerular injury in 31 patients with class III-V lupus nephritis (LN), 14 patients with non-proliferative proteinuric glomerulopathy and six normal controls. The expression of NF-kappaB subunits p65 and p50, and the NF-kappaB regulated proinflammatory mediators tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) as well as CD68 and synaptopodin was examined by Southwestern histochemistry (SWH) or immunohistochemistry. In contrast to non-proliferative glomerulopathy and normal controls, NF-kappaB activation (both p65 and p50) was enhanced in glomerular endothelial, mesangial cells or infiltrating cells in class IV LN, along with upregulation of TNF-alpha, IL-1beta, IL-6 and ICAM-1 expression. Glomerular endothelial and mesangial activation of NF-kappaB and mesangial ICAM-1 expression correlated with disease activity and the level of glomerular macrophage infiltration. Podocyte NF-kappaB overactivation (predominantly p65) paralleled podocyte expression of TNF-alpha and IL-1beta in patients with LN and non-proliferative glomerulopathy. Podocyte staining scores of NF-kappaB and p65 were positively correlated with the severity of proteinuria in LN and non-proliferative glomerulopathy. These results suggest a pathogenic role for NF-kappaB in glomerular injury by multiple mechanisms.

Pathogenesis of lupus nephritis: an update

Lupus nephritis (LN) is a prototypic autoimmune disease. Its immunopathogenesis is characterized by the loss of self-tolerance. In this article, we review our current understanding of the disease mediators of LN. There is ample evidence to suggest a pathogenic role of nephritogenic autoantibodies. These antibodies cross react with nucleosomal epitopes, and the in vivo generation of nucleosomes requires apoptosis. Furthermore, there is an intriguing and paradoxical relationship between complement and systemic lupus erythematosus (SLE). Immune complex-mediated activation of complement through the classic pathway is traditionally believed to be a major mechanism by which tissue injury occurs. In contrast, hereditary deficiencies of complement components increase the risk of SLE. Finally, the roles of reactive nitrogen and oxygen species are emphasized.

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.

Mycophenolate mofetil in nonlupus glomerulonephropathy

Mycophenolate mofetil (MMF) initially found widespread use in the immunoprophylaxis of rejection in organ transplantation. It has subsequently been used in lupus glomerulonephritis, where early studies have shown it to be effective in induction and maintenance therapy. The randomized studies have mostly studied small groups of patients and their conclusions do need to be confirmed in larger studies. MMF has also been used in small numbers of patients in a variety of nonlupus glomerulopathies, which have different underlying immunopathology as well as clinical course, including IgA nephropathy, membranous nephropathy, focal segmental glomerulosclerosis, membranoproliferative glomerulonephritis, hepatitis-C-associated glomerulonephritis and even Goodpasture's syndrome. In this article, we discuss its use in such nonlupus glomerular diseases.

Nitric oxide and glomerulonephritis

Glomerulonephritis is a common clinical condition that is caused by immune-mediated injury to the kidney and is characterized by dysfunction of the glomerular capillary filtration barrier. Nitric oxide (NO), a ubiquitous molecule with many biological functions throughout the body, has been evaluated as an inflammatory mediator in these circumstances. NO may induce glomerular injury directly or may act via stimulation of a host of other inflammatory mediators. A variety of experimental models of glomerulonephritis have been studied including those induced by infusion of antibodies to the Thy1.1 antigen or glomerular basement membrane, Heymann nephritis, and autoimmune nephritis. In virtually all of these cases there is evidence of increased NO production. Excessive production of NO by inducible nitric oxide synthase (iNOS), derived from infiltrating immune cells or resident glomerular cells, nearly always is associated with increased glomerular injury. Interventions that inhibit this enzyme result in less proteinuria and diminished glomerular damage. In contrast, NO derived from endothelial nitric oxide synthase (eNOS) may limit glomerular disease by preserving endothelial cell integrity. There are only a limited number of studies that have evaluated the impact of NO in patients with glomerulonephritis. Although the bulk of evidence supports a role of NO as a pro-inflammatory mediator in glomerulonephritis, additional work is needed to show an association between altered NO production and the severity and outcome of disease in patients with this disease. It is hoped that better understanding of the role of NO in glomerulonephritis will lead to the development of therapies to ameliorate the disease.

Mycophenolic acid inhibits activation of inducible nitric oxide synthase in rodent fibroblasts

Mycophenolate mofetil (MMF) is an immunosuppressive drug that acts as a selective inhibitor of inosine monophosphate dehydrogenase (IMPDH). MMF has recently been shown to inhibit the enzymatic activity of inducible NO synthase (iNOS) and subsequent production of the cytotoxic free radical nitric oxide (NO) in endothelial cells. We here investigated the effect of bioactive MMF compound mycophenolic acid (MPA) on iNOS-mediated NO synthesis in fibroblasts, which are important source of NO in rheumatoid arthritis and during rejection of solid organ transplants. MPA exerted dose-dependent inhibition of NO synthesis, measured as nitrite accumulation, in IFN-gamma + LPS-stimulated L929 mouse fibroblast cell line and rat primary fibroblasts. The effect of MPA was not mediated through interference with IMPDH-dependent synthesis of iNOS co-factor BH4 and subsequent suppression of iNOS enzymatic activity, as direct BH4 precursor sepiapterin failed to block the action of the drug. MPA suppressed the IFN-gamma + LPS-induced expression of fibroblast iNOS protein, as well as mRNA for iNOS and its transcription factor IRF-1, as assessed by cell-based ELISA and semiquantitative RT-PCR, respectively. MPA suppression of fibroblast NO release, iNOS, and IRF-1 activation, was efficiently prevented by exogenous guanosine, indicating that the drug acted through reduction of IMPDH-dependent synthesis of guanosine nucleotides. These results suggest that MPA inhibits NO production in fibroblasts by blocking guanosine nucleotide-dependent expression of iNOS gene, through mechanisms that might involve the interference with the induction of iNOS transcription factor IRF-1.

Mycophenolate mofetil prevents arteriolopathy and renal injury in subtotal ablation despite persistent hypertension

BACKGROUND

Although renal protective effect of interrupting the inflammatory process is well established, it is still controversial if it also prevents the glomerular hemodynamic disturbances that initiate renal injury. We investigated the effects of suppressing inflammation with mycophenolate mofetil (MMF) on glomerular hemodynamics, arteriolar structural changes, and renal histologic injury in rats with subtotal renal ablation

METHODS

Micropuncture studies were performed 30 days after 5/6 nephrectomy in rats untreated and treated with MMF (30 mg/kg/day). Renal histology, immunohistochemistry for lymphocytes, macrophages and inducible nitric oxide synthase (iNOS) expression, as well as afferent arteriolar (AA) morphometry was evaluated.

RESULTS

Renal ablation significantly increased proteinuria (6.8 to 82.7 mg/day), mean arterial pressure (MAP) (120 to 166 mm Hg), single-nephron glomerular filtration rate (SNGFR) (34.8 to 56.3 nL/min), glomerular plasma flow (QA) (117.7 to 246.9 nL/min), and glomerular capillary pressure (PGC) (48.9 to 61.0 mm Hg). Afferent resistance (AR), efferent resistance, and ultrafiltration coefficient remained unchanged. Despite persisting arterial hypertension (152 mm Hg), MMF prevented proteinuria (13.3 mg/day), and significantly reduced SNGFR (44.4 nL/min), PGC (49.1 mm Hg), and QA (163.2 nL/min) due to a rise in AR (3.13 vs. 2.18 1010 dyn/sec/cm-5). Glomerular sclerosis, tubulointerstitial damage, lymphocyte and macrophage infiltration, and iNOS expression were significantly reduced by MMF, in addition hypertrophy of AA resistance evaluated by the media/lumen ratio was prevented (P < 0.001).

CONCLUSIONS

Reduction in proteinuria, SNGFR, QA, and PGC, despite elevated MAP, indicate preservation of AA function. These results suggest that inflammation associated arteriolopathy of AA contributes to glomerular hemodynamic disturbances that participate in the progression of renal disease.

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

The incidence of progressive nephropathies and, consequently, the population suffering from end-stage renal disease have increased steadily in recent years, posing an ever-growing cost, in both human and financial terms, to society. There is mounting evidence that, in both immune-mediated and nonimmune-mediated chronic nephropathies, renal inflammatory events are key to the propagation and perpetuation of renal injury. Mycophenolate mofetil (MMF) is an antilymphocyte agent recently introduced in clinical practice for the prevention of allograft rejection. The present review discusses clinical and experimental evidence that the anti-inflammatory action of MMF can be advantageously used to arrest immune- and nonimmune-mediated progressive injury of native kidneys as well.

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.

Mediators of injury in lupus nephritis

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by the production of autoantibodies and the development of immune complex glomerulonephritis. Lupus nephritis (LN) remains a leading cause of morbidity and mortality in SLE. As a result, defining pathogenetic mediators in LN remains a major research effort. Progression to LN in SLE is dependent on the host breaking immune tolerance and forming autoantibodies that deposit in the kidney. A variety of predisposing factors in the host must then be present for this event to result in renal pathology. In this article, the authors review recent reports that advance our understanding of LN disease mediators, from autoantibody production and immune complex deposition to end stage fibrosis.