Effects of mycophenolate mofetil in mercury-induced autoimmune nephritis

Genotype and Outcome After Kidney Transplantation in Alport Syndrome

Introduction

Alport syndrome (AS) is caused by mutations in α3/α4/α5 (IV) collagen genes, the severity of which determine the progression of AS. Posttransplantation outcome is good, although anti-glomerular basement membrane (anti-GBM) glomerulonephritis occurs in 3% to 5% of recipients, clustering in patients with a severe mutation. We assessed whether the severity of the underlying AS mutation affects graft and patients outcome after transplantation, including the occurrence of anti-GBM nephritis.

Methods

We included 73 AS patients with an identified mutation (COL4A5, 57 patients; COL4A3, 9 patients; COL4A4, 6 patients; heterozygous composite COL4A3 and A4, 1 patient) who underwent transplantation between 1971 and 2014 and who had received a total of 93 kidney grafts.

Results

In all, 41 patients had a severe mutation (COL4A5, 30 patients; COL4A3, 6 patients; COL4A4, 5 patients), and 32 had a nonsevere mutation (COL4A5, 27 patients; COL4A3, 4 patients; COL4A4, 1 patient). Patient survival was similar in patients with severe and nonsevere mutations (89% vs. 84% at 5 years, 83% vs. 75% at 10, 15, and 20 years; P = 0.46). Graft survival was not affected by the severity of mutation (77% vs. 63% at 5 years, 60% vs. 55% at 10 years, 55% vs. 55% at 15 years, and 55% vs. 50% at 20 years; P = 0.65). Clinically significant anti-GBM glomerulonephritis occurred in 1 male patient with severe COL4A5 mutation 6 years after transplantation recurred in a subsequent graft, leading twice to graft loss.

Conclusion

Although severe mutations affect the severity of AS, they do not have an impact on patient and graft survival after transplantation. De novo anti-GBM nephritis after transplantation was less frequent than previously reported, occurring in only 1.4% of AS patients, and in 2% of males with COL4A5 mutation.

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.

Protective effect of mycophenolate mofetil against nephrotoxicity and hepatotoxicity induced by tacrolimus in Wistar rats

Tacrolimus (TAC), a calcineurin inhibitor (CNI), is clinically used as an immunosuppressive agent in the transplant recipient; however, the use of TAC is greatly limited by its nephrotoxicity and hepatotoxicity. Mycophenolate mofetil (MMF), an inhibitor of the purine synthesis, has been used in combination with many immunosuppressive drugs such as TAC. The association TAC/MMF was used in organ transplantation to increase the efficiency and reduce acute rejection rates, but the effects of MMF on TAC-induced kidney and liver injuries are still not well investigated. The aims of this study are to explore whether MMF co-administration with TAC has a renoprotective and hepatoprotective effect against TAC-induced renal and hepatic injuries and to check the implication of oxidative stress in the MMF's possible protective effect. Our results showed that MMF (at 50 mg kg(-1) body weight (b.w.)) restored creatinine, in addition to increased AST and ALT levels by TAC (at 60 mg kg(-1) b.w.). Furthermore, MMF decreased DNA damage induced by TAC in the kidney and liver of rats as assessed by comet assay. This renoprotective and hepatoprotective effect of MMF was associated with an antioxidant effect. In fact, MMF co-treatment with TAC decreased oxidative damage induced by TAC. It reduced malondialdehyde (MDA) and protein carbonyl (PC) levels as well as catalase and superoxide dismutase (SOD) activities. We conclude that the co-administration MMF with TAC protect liver and kidney against TAC toxicity via an antioxidant process.

Lupus-like oral mucosal lesions in mercury-induced autoimmune response in Brown Norway rats

Background

Administration of mercury at nontoxic doses induces systemic autoimmune disease in Brown Norway (BN) rats. The pathogenesis of lupus-like oral mucosal lesion by mercury-induced autoimmunity is still unclear, even though the oral mucosa is observed to be commonly affected in mercury-treated BN rats. In this study, we investigated the immunopathology of lupus-like oral mucosal lesions in a model of mercury-induced systemic autoimmunity.

Methods

Brown Norway male rats were injected subcutaneously with either phosphate-buffered saline (control) or mercury at a dose of 1.0 mg per kilogram of body weight on days 0, 3, 5, and 7. Blood, kidney, and tongue samples were taken at various timepoints for evaluation by immunohistochemistry, RT-PCR, and lupus band test (LBT).

Results

Oral mucosal lesions were classified according to three consecutive temporal phases on the basis of infiltration of immunocompetent cells as follows: (phase I) infiltration of MHC class II⁺ dendritic cells (DC) and macrophages; (phase II) addition of ED1⁺ macrophage infiltrates; and (phase III) focal infiltration of pan T cells following increased infiltration of DC and macrophages. Dense infiltration of DC and macrophages was observed in the basement membrane (BM) zone of the oral epithelium. Tissue expression of IL-4 mRNA was detected in early lesions (phase I), suggesting that locally produced IL-4 may be responsible for Th2-mediated immune response. A linear and continuous smooth pattern of fluorescence was observed in the oral epithelial BM in addition to renal glomeruli, indicating immune complex deposits.

Conclusions

Local autoimmune responses are involved in the pathogenesis of mercury-induced lupus-like lesions of the oral mucosa.

Protein adducts of malondialdehyde and 4-hydroxynonenal contribute to trichloroethene-mediated autoimmunity via activating Th17 cells: dose- and time-response studies in female MRL+/+ mice

Trichloroethene (TCE), a common occupational and environmental toxicant, is known to induce autoimmunity. Previous studies in our laboratory showed increased oxidative stress in TCE-mediated autoimmunity. To further establish the role of oxidative stress and to investigate the mechanisms of TCE-mediated autoimmunity, dose- and time-response studies were conducted in MRL+/+ mice by treating them with TCE via drinking water at doses of 0.5, 1.0 or 2.0mg/ml for 12, 24 or 36 weeks. TCE exposure led to dose-related increases in malondialdehyde (MDA)-/hydroxynonenal (HNE)-protein adducts and their corresponding antibodies in the sera and decreases in GSH and GSH/GSSG ratio in the kidneys at 24 and 36 weeks, with greater changes at 36 weeks. The increases in these protein adducts and decreases in GSH/GSSG ratio were associated with significant elevation in serum anti-nuclear- and anti-ssDNA-antibodies, suggesting an association between TCE-induced oxidative stress and autoimmune response. Interestingly, splenocytes from mice treated with TCE for 24 weeks secreted significantly higher levels of IL-17 and IL-21 than did splenocytes from controls after stimulation with MDA-mouse serum albumin (MSA) or HNE-MSA adducts. The increased release of these cytokines showed a dose-related response and was more pronounced in mice treated with TCE for 36 weeks. These studies provide evidence that MDA- and or HNE-protein adducts contribute to TCE-mediated autoimmunity, which may be via activation of Th17 cells.

Mycophenolic acid suppresses granulopoiesis by inhibition of interleukin-17 production

Mycophenolic acid is a commonly used immunosuppressant after organ transplantation and in autoimmune diseases; however, myelosuppression is a major complication despite its largely favorable side-effect profile. Mycophenolic acid targets inosine monophosphate dehydrogenase, which is essential for T-cell proliferation. The T-cell cytokine interleukin-17 (IL-17 or IL-17A) and its receptor maintain normal neutrophilic granulocyte numbers in mice by induction of granulocyte-colony-stimulating factor. To test whether mycophenolic acid induces neutropenia by inhibiting IL-17-producing T cells, we treated C57Bl/6 mice with mycophenolate-mofetil (the orally available pro-drug) and found a dose-dependent decrease in blood neutrophils. This myelosuppressive effect was completely abolished in mice that lack the IL-17 receptor. Mycophenolic acid delayed myeloid recovery after bone marrow transplantation and decreased the percentage of IL-17-producing T cells in the spleen and thymus, and inhibited IL-17 production in human and mouse T cells in vitro. Injection of IL-17 during mycophenolic acid treatment overcame the suppression of the circulating neutrophil levels. Our study shows that mycophenolic acid suppresses neutrophil production by inhibiting IL-17 expression, suggesting that measurement of this interleukin might be useful in estimating the risk of neutropenia in clinical settings.

Successful treatment of resistant antiglomerular basement membrane antibody positivity with mycophenolic acid

Anti-glomerular basement membrane (GBM) antibody disease may progress to end-stage renal failure, requiring either dialysis or renal transplantation. In patients with end-stage renal disease (ESRD) due to anti-GBM-ab disease, the recurrence rate after transplantation is as high as 50% (2) and delaying renal transplantation until circulating anti-GBM antibody levels have been undetectable for at least 12 months reduces the recurrence rate to 5-15%. We report a case of ESRD due to renal limited anti-GBM disease with circulating anti-GBM-ab resistant to standard treatment approach who achieved undetectable anti-GBM-ab with mycophenolic acid.

Effects of mycophenolate mofetil for patients with crescentic lupus nephritis

OBJECTIVE

To compare the effects, relapse ratio and outcomes between mycophenolate mofetil (MMF) and pulse intravenous cyclophosphamide (CTX) for the induction therapy in patients with crescentic lupus nephritis.

METHODOLOGY

This is a retrospective, controlled study. Twenty-seven MMF therapeutic and twenty-five CTX therapeutic lupus patients with >or=50% crescent formation were enrolled in this study. The general conditions, clinicopathological findings, remission and relapse ratio, and outcomes of them were compared.

RESULTS

There was no significant difference of general condition and clinicopathological findings between MMF and CTX group. At 12 months, the total remission ratio in MMF and CTX group were 73.1% and 69.6%, while the complete remission ratio in MMF group (53.8%) was significantly higher than that in CTX group (26.1%). The relapse ratio in MMF group (10.5%) was significantly lower than in CTX group (43.8%). Forty per cent of PR patients in CTX group suffered from relapse. Until June 2005, the patients in CTX group received a follow time with 38.5 +/- 21.2 (range 10 approximately 80) months, and in MMF group the follow time was 41.1 +/- 27.0 (range 12 approximately 90) months. Two patients in MMF group and two in CTX group entered into end stage renal failure. The side effect of infection was more significant in CTX group.

CONCLUSION

Higher complete remission ratio and lower relapse ratio were observed in MMF group than in CTX group. The side effect of infection was more infrequent in MMF group, which showed preferable security of MMF.

Cell adhesion molecules in chemically-induced renal injury

Cell adhesion molecules are integral cell-membrane proteins that maintain cell-cell and cell-substrate adhesion and in some cases act as regulators of intracellular signaling cascades. In the kidney, cell adhesion molecules, such as the cadherins, the catenins, the zonula occludens protein-1 (ZO-1), occludin and the claudins are essential for maintaining the epithelial polarity and barrier integrity that are necessary for the normal absorption/excretion of fluid and solutes. A growing volume of evidence indicates that these cell adhesion molecules are important early targets for a variety of nephrotoxic substances including metals, drugs, and venom components. In addition, it is now widely appreciated that molecules, such as intracellular adhesion molecule-1 (ICAM-1), integrins, and selectins play important roles in the recruitment of leukocytes and inflammatory responses that are associated with nephrotoxic injury. This review summarizes the results of recent in vitro and in vivo studies indicating that these cell adhesion molecules may be primary molecular targets in many types of chemically-induced renal injury. Some of the specific agents that are discussed include cadmium (Cd), mercury (Hg), bismuth (Bi), cisplatin, aminoglycoside antibiotics, S-(1,2-dichlorovinyl)-l-cysteine (DCVC), and various venom toxins. This review also includes a discussion of the various mechanisms, by which these substances can affect cell adhesion molecules in the kidney.

Effects of mycophenolate mofetil on cisplatin-induced renal dysfunction in rats

PURPOSE

Inflammation and oxidative stress are important events among the plethora of mechanisms involved in cisplatin (CDDP)-induced nephrotoxicity. The aim of this study was to evaluate the effect of mycophenolate mofetil (MMF), an immunosuppressive, in the protection against CDDP-induced renal dysfunction.

METHODS

Rats were divided into four groups; untreated-control group, CDDP-treated group (7 mg/kg, single intraperitoneal dose), MMF-treated group (40 mg/kg/day orally for 5 successive days) and the fourth group was treated with both drugs and MMF treatment was started 1 day prior to CDDP administration. Nephrotoxicity was assessed 7 days after the CDDP treatment by measuring serum indices of nephrotoxicity, kidney weight as a percentage of total body weight, kidney's tissue peroxidative alterations and total nitrate/nitrite concentration (NOx) and the results were confirmed histopathologically.

RESULTS

Rats treated with CDDP showed marked nephrotoxicity as evidenced from the significant increase in serum creatinine and urea levels and decrease in serum calcium and albumin levels. Kidneys of CDDP-treated rats showed significant increases in kidney weight and malondialdehyde (MDA) production level and decreases in total NOx concentration, glutathione peroxidase (GPx) activity and reduced glutathione (GSH) content levels. Histopathological assessment of kidneys of CDDP-treated rats revealed extensive tubular necrosis with "sloughing off" of the renal tubular lining cells, intratubular hyaline casts and mononuclear cell infiltration. Treatment with MMF significantly protected the rats against CDDP-induced nephrotoxicity. The rise in serum creatinine and urea levels, kidney weight and kidney tissue MDA production, depletion of "endogenous antioxidant reserve" including GPx activity and reduced GSH content levels and the deleterious histopathological changes induced by CDDP treatment were significantly mitigated by MMF treatment.

CONCLUSIONS

MMF treatment dramatically ameliorates CDDP-induced renal dysfunction.

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.

Prevention of glomerular crescent formation in glomerulonephritis by mycophenolate mofetil in rats

BACKGROUND

Glomerular crescent formation is a prominent feature of aggressive forms of glomerulonephritis (GN) and is associated with a poor prognosis. We investigated whether the potent immunosuppressive agent mycophenolate mofetil (MMF) could prevent crescent formation in a model of anti-glomerular basement membrane (GBM) GN in the rat.

METHODS

GN with glomerular crescents was induced by the injection of anti-GBM antibody to female Wistar-Kyoto (WKY/NCrj) rats. The experimental rats were divided into two groups: rats received vehicle (0.5% carboxymethylcerlose) or MMF (20 mg/kg/day) orally. Body weight was measured and the urine and blood samples were evaluated. The rats were sacrificed at day 14, and histological analysis was performed. The mRNA expression of cytokines and adhesion molecules in the kidney was analysed by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Marked proteinuria, glomerular crescent formation and glomerulosclerosis were observed in this model, and these were significantly reduced by MMF treatment. Marked glomerular macrophage and T-cell infiltration was also observed, and MMF treatment significantly inhibited macrophage but not T-cell infiltration. RT-PCR and immunohistochemical analysis revealed that mRNA and protein expression of osteopontin was decreased by the treatment with MMF. In addition, MMF treatment in the early stages of GN could inhibit proteinuria, glomerular crescent formation and glomerulosclerosis.

CONCLUSIONS

These findings suggest therapeutic potential for MMF in the inhibition of glomerular crescent formation in GN and provide new insights into the mechanism underlying the amelioration of crescentic GN by MMF treatment.

Immunosuppressive treatment protects against angiotensin II-induced renal damage

Angiotensin (Ang) II promotes renal infiltration by immunocompetent cells in double-transgenic rats (dTGRs) harboring both human renin and angiotensinogen genes. To elucidate disease mechanisms, we investigated whether or not dexamethasone (DEXA) immunosuppression ameliorates renal damage. Untreated dTGRs developed hypertension, renal damage, and 50% mortality at 7 weeks. DEXA reduced albuminuria, renal fibrosis, vascular reactive oxygen stress, and prevented mortality, independent of blood pressure. In dTGR kidneys, p22phox immunostaining co-localized with macrophages and partially with T cells. dTGR dendritic cells expressed major histocompatibility complex II and CD86, indicating maturation. DEXA suppressed major histocompatibility complex II+, CD86+, dendritic, and T-cell infiltration. In additional experiments, we treated dTGRs with mycophenolate mofetil to inhibit T- and B-cell proliferation. Reno-protective actions of mycophenolate mofetil and its effect on dendritic and T cells were similar to those obtained with DEXA. We next investigated whether or not Ang II directly promotes dendritic cell maturation in vitro. Ang II did not alter CD80, CD83, and MHC II expression, but increased CCR7 expression and cell migration. To explore the role of tumor necrosis factor (TNF)-alpha on dendritic cell maturation in vivo, we treated dTGRs with the soluble TNF-alpha receptor etanercept. This treatment had no effect on blood pressure, but decreased albuminuria, nuclear factor-kappaB activation, and infiltration of all immunocompetent cells. These data suggest that immunosuppression prevents dendritic cell maturation and T-cell infiltration in a nonimmune model of Ang II-induced renal damage. Ang II induces dendritic migration directly, whereas in vivo TNF-alpha is involved in dendritic cell infiltration and maturation. Thus, Ang II may initiate events leading to innate and acquired immune response.