A new acute inflammatory syndrome related to the introduction of mycophenolate mofetil in patients with Wegener's granulomatosis

Bart Maes1,, Michael Oellerich2, Jan L. Ceuppens3, Victor W. Armstrong2, Pieter Evenepoel1, Dirk Kuypers1, Thierry Messiaen1, Maria Shipkova2, Eberhard Wieland2 and Yves Vanrenterghem1

1 Department of Nephrology, University Hospital Gasthuisberg, Leuven, Belgium, 2 Department of Clinical Chemistry, Georg-August-Universität, Göttingen, Germany and 3 Department of Clinical Immunology, University Hospital Gasthuisberg, Leuven, Belgium



   Abstract
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 Abstract
 Introduction
 Cases
 Discussion
 References
 
Mycophenolate mofetil (MMF) is increasingly used for prevention of allograft rejection and to treat immune disorders. We report the development of an acute inflammatory syndrome in two patients with Wegener's granulomatosis after MMF was introduced, because of persistent renal and systemic disease activity despite cyclophosphamide treatment. Within 1 week both patients developed an acute inflammatory syndrome, characterized by fever, arthralgias and muscle pain. No infection could be detected and no indications for increased Wegener's activity were present. MMF was stopped resulting in a rapid and complete resolution of the syndrome. A rechallenge with 2 g of MMF in the second patient resulted in a relapse of the syndrome within 4 days. There was an association between symptoms and increased levels of mycophenolic acid (MPA) acyl glucuronide and serum interleukin-6, suggesting the induction of inflammatory cytokines by MPA acyl glucuronide as the cause of the syndrome. Therefore, special attention should be given to side effects such as fever, arthralgias and muscle pain when treating patients with Wegener's granulomatosis during the active phase. Because this side effect of MMF may also occur after solid organ transplantation and in other immune disorders, pharmacokinetic profiling of MPA and MPA acyl glucuronide is needed in future studies with MMF.

Keywords: cytokines; inflammatory syndrome; mycophenolate mofetil; Wegener's granulomatosis



   Introduction
 Top
 Abstract
 Introduction
 Cases
 Discussion
 References
 
Wegener's granulomatosis, an antineutrophil cytoplasmic autoantibody associated systemic vasculitis of small and medium vessels, is one of the most common causes of rapidly progressive glomerulonephritis. The standard therapy originates from the late 1960s and consists of oral corticosteroids and oral cyclophosphamide for at least 12 months after induction of remission. Despite a dramatic reduction of mortality, cyclophosphamide causes a substantial acute (e.g. myelosuppression with risk for infection) and long-term (e.g. bladder carcinoma, lymphoma) dose-related toxicity [1].

Therefore, multiple strategies have been explored to either reduce the total dose of and/or duration of therapy with cyclophosphamide or to substitute cyclophosphamide by a less toxic drug. In the case of Wegener's granulomatosis, dose reduction of cyclophosphamide (monthly intraveneous pulse therapy) proved to be less toxic with equal remission induction rates, but increased relapse rates [2]. Also reduction of the treatment time with cyclophosphamide without introduction of another immunosuppressant was shown to result in more frequent relapses. Together with other immunosuppressive drugs, methotrexate may be used successfully for ‘limited’ Wegener's granulomatosis [3]. Cyclophosphamide can also be substituted, from the induction phase and in limited disease only, by methotrexate and even by trimethprim-sulphametoxazol, but apparently not by azathioprine [1,45].

Mycophenolic acid (MPA), derived from mycophenolate mofetil (MMF) by gastrointestinal tissue and systemic esterase activity, is a potent, reversible, and non-competitive inhibitor of inosine 5'-monophosphate dehydrogenase, a key enzyme for de novo purine synthesis and for the glycosylation of adhesion molecules in T and B lymphocytes. As such, MPA selectively inhibits the proliferation of T and B lymphocytes, the production of antibodies, the generation of cytotoxic T cells and the recruitment of leukocytes to sites of inflammation. Treatment with MMF decreased the incidence of acute rejection in the first 6 months after renal transplantation by approximately 50% compared with placebo or azathioprine. Results after 3 years also demonstrated that MMF is a highly effective immunosuppressive drug with an acceptable safety profile [6]. MMF has become one of the standard immunosuppressive agents in many transplant centres and has been successfully used in (short-term) pilot studies to treat diverse glomerulopathies and immune disorders, including stabilization of remission in Wegener's granulomatosis [79]. In this report, we describe the development of an acute inflammatory syndrome in two patients with Wegener's granulomatosis in association with the introduction of MMF.



   Cases
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 Abstract
 Introduction
 Cases
 Discussion
 References
 
Case 1
On September 21, 1998, a 63-year-old woman with a 16-year old history of relapsing Wegener's granulomatosis was admitted to hospital because of serious muscle pain in the lower extremities, 3 days after the introduction of MMF. One month earlier, a new induction therapy with oral cyclophosphamide and oral corticosteroids had been initiated on account of a relapse (nephritic sediment and increase in serum creatinine, sinusitis, c-ANCA>1/1280, anti-PR3 155 AU/l). Despite a good clinical and biochemical response, she developed leukopenia (2x109/l). Because leukopenia already had been complicated with severe gluteal herpes zoster infections and bacterial meningitis and because of the high cumulative dose of cyclophosphamide (95 g), the latter was substituted by MMF 2 g/day once the leukopenia had recovered (>3.5x109/l). Three days after the introduction of MMF, she developed fever up to 38.1°C, severe muscle pain in both legs, debilitating weakness in the lower extremities, arthralgia in both knees and ankles and monoarthritis of the proximal interphalangeal joint of the fourth left finger. Laboratory tests were indicative of an inflammatory process: white blood cell count 6300/mm3, erythrocyte sedimentation rate 80 mm/h and C-reactive protein 181 mg/dl (see Figure 1AGo). Other changes in baseline values of laboratory tests are shown in Table 1Go. There were no major changes in renal function or urine analysis (sediment, proteinuria) nor in the titre of c-ANCA (1/320) or anti-PR3 (55 AU/l). Cultures of blood, urine and sputum were negative. Cytomegalovirus buffy coat and serology, hepatitis B and C, and Epstein-Barr serology remained negative. There was no eosinophilia and IgE was within normal limits. Radiographic examination of the chest, knees, sinuses, ankles and hands, ultrasound examination of the abdomen and a CT scan of the thorax revealed no abnormalities. Duplex ultrasound of the venous structures in the legs was negative. Electromyography of the four limbs was normal. A punctate of the swollen proximal interphalangeal joint of the fourth left finger was negative for crystals and on culture. After MMF was stopped, all complaints disappeared within 48 h, and C-reactive protein showed a rapid return towards basal values (Figure 1AGo).



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Fig. 1.  Plasma concentrations of C-reactive protein in relation to the intake of MMF as a function of time (A, patient 1; B, patient 2).

 

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Table 1.  Major changes in laboratory tests after introduction of MMF

 

Case 2
On June 2, 1999, a 47-year-old man with a 6-year history of Wegener's granulomatosis (with predominant pulmonary relapsing manifestations) was referred to our hospital because of renal insufficiency. Because of an active biopsy-proven pauci-immune necrotizing glomerulonephritis and generalized manifestations, a treatment with oral corticosteroids and oral cyclophosphamide was started. A good clinical and biochemical response was obtained: serum creatinine dropped from 3 to 1.4 mg/dl, the initial nephritic urine sediment normalized, arthralgia and upper airway symptoms disappeared, c-ANCA dropped from 1/320 to 0 and anti-PR3 from 81 to 0 AU/l. On October 6, 2000, the disease flared up with renal and pulmonary manifestations; c-ANCA increased to 1/160 and anti-PR3 to 100 AU/l. In association with corticosteroids (Medrol® 32 mg/day), MMF was started at a dose of 2 g/day in order to control the disease since he had received a cumulative dose of cyclophosphamide of 96 g. Five days later, he was admitted to the hospital because of general malaise, fever up to 39.5°C, anorexia, diffuse muscle pain, arthritis of the right wrist and jumping arthralgia, resistant to paracetamol (Prodafalgan® 6 g/d), and tramadolhydrochloride (Contramal® 400 mg/d). Laboratory results were consistent with a severe inflammatory response: white blood cell count of 36 300/mm3, an erythrocyte sedimentation rate of 118 mm/h and a C-reactive protein level of 410 mg/dl (see Figure 1BGo). There were no urinary or renal function abnormalities, but elevations in the levels of alkaline phosphatase (AF), {gamma}-glutamyltransferase ({gamma}-GT), alanine aminotransferase (ALT) and creatinine phosphokinase (CPK) were observed (see Table 1Go). There were no indices of increased activity of Wegener's granulomatosis (urine sediment, titre of c-ANCA (1/80) or anti-PR3 (80 AU/l)). Cultures of blood, urine and sputum were negative. Cytomegalovirus buffy coat and serology, hepatitis B and C, Epstein-Barr and Parvovirus B19 serology remained negative. No eosinophila was present. Radiographic examination of the chest, sinuses, ankles and hands, ultrasound examination of the abdomen and the heart valves revealed no inflammatory process. Electromyography of the four limbs was normal. After stopping MMF, all complaints disappeared within 48 h and CRP levels returned to basal values (Figure 1BGo).

Four days later, MMF was restarted at 2 g/day. From the second day on, the patient again experienced diffuse muscle pain, fever up to 38°C, jumping arthralgia, however, with inflammatory symptoms in the right wrist; tramadolhydrochloride (Contramal® 400 mg/day) needed to be restarted. Again, no focus of infection nor an increased disease activity could be demonstrated, and MMF was stopped after 4 days followed by a restitutio ad integrum. Pre-dose plasma concentrations of MPA and its acylglucuronide metabolite (AcMPAG) were determined using an HPLC method [10] during this rechallenge. Pre-dose levels of MPA ranged from 0.94 to 1.76 µg/ml, while AcMPAG concentrations ranged from 0.30 to 0.43 µg/ml (Table 2Go). Plasma concentrations of interferon-{gamma} (IF-{gamma}) and interferon-{alpha} (IF-{alpha}) remained low, while levels of interleukin-6 (IL-6) seemingly coincided with the inflammatory state (Table 2Go).


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Table 2.  Plasma concentrations of MPA, AcMPAG and cytokines before, during and after rechallenge in patient 2

 



   Discussion
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 Abstract
 Introduction
 Cases
 Discussion
 References
 
Because of its mode of action and its efficacy in organ transplantation, MMF has recently been introduced with promising short-term results in a spectrum of immune disorders and glomerulopathies [79]. Initial reports on its use in Wegener's granulomatosis suggest that MMF is able to maintain a stable remission in the majority of patients, with a further reduction of the grumbling disease activity and a further reduction of the need for corticosteroids [89].

Moreover, MMF is not only efficacious, but also attractive because of its relatively low toxicity and good clinical tolerance. The long-term safety profile of MMF in conjunction with other immunosuppressants in renal transplantation was quite favourable: gastrointestinal complaints (mainly diarrhoea and vomiting), leukopenia and tissue-invasive cytomegalovirus disease are the most common side-effects, and there was only a small dose-dependent increase of lymphoproliferative disorders and of non-skin carcinomas [6]. In a study in Wegener's granulomatosis, gastrointestinal complaints, leukopenia and respiratory infection were the most frequently noted side effects and one patient developed cytomegalo-virus-colitis [8].

The gastrointestinal side effects associated with MMF are not well explained. Recently, it has been suggested that they may be caused by the acyl glucuronide of MPA, in analogy with the intestinal injury caused in rats by the acyl glucuronide of diclofenac [11,12]. However, the exact mechanism of injury is still unknown. MPA, the active metabolite released from mycophenolate mofetil by esterase activity, is primarily metabolized in the liver to 7-O-MPA-ß-glucuronide, but also to AcMPAG. While the former is neither active nor reactive and is rapidly excreted, AcMPAG has been shown to induce proinflammatory cytokine expression and release by human mononuclear cells [11].

In this report, we describe an acute inflammatory syndrome associated with the introduction of MMF in two patients with longstanding Wegener's granulomatosis. Because of the apparent temporal relationship, the recurrence during rechallenge in one patient and the absence of other possible explanations, it is tempting to hypothesize that this may be due to systemic proinflammatory cytokine release, induced by AcMPAG. Measurements of this metabolite and of cytokines in this patient further support this hypothesis.

The question then arises whether this inflammatory syndrome after introduction of MMF is specific for Wegener's granulomatosis. Although doses of MMF sometimes have to be reduced in patients after solid organ transplantation because of general malaise and intolerance, an acute unexplained severe inflammatory syndrome has never been reported; nor has such a syndrome been observed in patients with other immune disorders treated with MMF. The fact that this syndrome may be masked by concomitant intake of other immunosuppressive drugs after organ transplantation is unlikely since the two patients in this report were taking steroids, and immunosuppression in patients with organ transplantation or immune disorders may sometimes consist only of MMF in monotherapy. The pre-dose concentrations of AcMPAG measured in these two patients are commonly encountered in renal transplant recipients, and concentrations of >0.6 µg/ml 12 h after the MMF dose have been reported [10]. However, high pre-dose concentrations of AcMPAG are uncommon in patients with other immunologic renal diseases (AcMPAG 0.15 mg/l, range <0.03–0.4 (n=29) (Shipkova et al., unpublished)). It can be speculated that patients with Wegener's granulomatosis host an abnormal population of monocytes-macrophages, that is not only related to the pathogenesis of the disease, but that is also very sensitive to the proinflammatory effects of AcMPAG. This could either be a primary defect or a result of disease activity, or it may be induced by the high cumulative dose of cyclophosphamide given to these patients. In this respect it should be noted that considerable variation was observed in the proinflammatory response to AcMPAG in mononuclear cells from healthy individuals [11], suggesting that some cell populations may be more susceptible to proinflammatory stimuli.

For a better understanding of the underlying mechanisms of this inflammatory syndrome in response to MMF administration, careful monitoring of MPA and in particular its AcMPAG metabolite is essential for future studies.

In conclusion, the introduction of MMF at a dose of 2 g/day in two patients with relapsing Wegener's granulomatosis resulted in an acute inflammatory syndrome, necessitating the interruption of the therapy. We hypothesize that inflammation was due to AcMPAG, a metabolite of MPA with toxic effects, and that is known to induce proinflammatory cytokines in mononuclear cells. This observation may not only be important for the pathogenesis of Wegener's granulomatosis, but also in the treatment of transplant recipients and patients with other immune disorders. Therefore, pharmacokinetic profiling of MPA and AcMPAG in future studies is mandatory in order to optimize MMF-containing immunosuppressive regimens.



   Acknowledgments
 
Dr M. Shipkova was supported by a grant from the Georg-August-University, Göttingen.



   Notes
 
Correspondence and offprint requests to: Bart Maes, Department of Nephrology, University Hospital Gasthuisberg, B-3000 Leuven, Belgium. Email: Bart.Maes{at}UZ.KULeuven.ac.be Back



   References
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 Abstract
 Introduction
 Cases
 Discussion
 References
 

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Received for publication: 21. 9.01
Accepted in revised form: 22. 1.02