Imatinib mesylate, a new kid on the block for the treatment of anti-neutrophil cytoplasmic autoantibodies-associated vasculitis?

Persistent T cell activation is a common finding in anti-neutrophil cytoplasmic autoantibodies (ANCA)-associated systemic vasculitis (AAV) patients. Because imatinib, a selective inhibitor of the ABL, ARG, PDGFR and c-KIT tyrosine kinases, inhibits T cell activation, this study was conducted to evaluate the potential use of imatinib for the treatment AAV patients refractory to conventional therapy. In particular, we investigated the inhibition of T cell activation by this drug and its efficacy on activated T cells from anti-neutrophil cytoplasmic autoantibodies (ANCA)-associated systemic vasculitides (AASV) patients. T cell stimulation has been induced by anti-CD3/anti-CD28 antibodies or by phorbol myristate acetate (PMA)/ionomycin. T cell proliferation was analysed by tritiumthymidine incorporation. Cell cycle progression was determined by propidium iodide staining using fluorescence activated cell sorter (FACS) analysis and by RNAse protection assay (RPA). Cytokine levels were assessed by enzyme-linked immunosorbent assay. T cell proliferation was inhibited significantly by imatinib, due most probably to cell cycle arrest in the G1-phase. This was paralleled by inhibition in the expression of cyclin-dependent kinases 1 and 2 mRNA. The expression of CD25 in naive and memory T cells was decreased significantly by imatinib in activated T cells. Similarly, conversion from naive to memory T cells after T cell activation was impaired by imatinib. Imatinib did not influence interleukin-2 and tumour necrosis factor-alpha production but increased interferon-gamma production. These observed effects of imatinib were similar in T cells from AASV patients and from healthy individuals. Imatinib might be an alternative therapeutical option for AASV patients refractory to conventional therapy.

Dopamine treatment in brain-dead rats mediates anti-inflammatory effects: the role of hemodynamic stabilization and D-receptor stimulation

Brain death (BD) is associated with profound inflammation in end-organs. Dopamine (DA) treatment reduces this inflammatory response, but the underlying mechanisms remain thus far largely unknown. In this study, we investigated if the anti-inflammatory effect of DA was related to hemodynamic stabilization and by which receptors it was mediated. BD was induced in F344 donor rats. DA was given either before BD for 24 h or after BD induction during a definite time. Adrenergic or D-receptor blockers were administered to inhibit the receptor stimulation mediated by DA. Hemodynamic changes were recorded and kidneys were harvested after 6 h of BD. Mean arterial pressure was completely normalized by DA treatment. DA pretreatment before BD induction and treatment during BD both significantly inhibited the monocyte infiltration. The anti-inflammatory as well as its blood pressure stabilizing effect was abrogated by concomitant application of adrenergic receptor blockers. In contrast, concomitant application of D-receptor blockers only abrogated the anti-inflammatory effect, but did not affect blood pressure stabilization. In contrast, pergolide and adrenergic receptor blockers completely normalized the blood pressure, but did not affect renal inflammation. Hence, DA might reduce BD-induced monocyte infiltration possibly by hemodynamic stabilization, D-receptor activation, or a combination of both.

Influence of hypersulfated and low molecular weight heparins on ischemia/reperfusion: injury and allograft rejection in rat kidneys

The aim of the study was to evaluate the effect of the hypersulfated nonanticoagulant heparin derivative LU 51198 (LU) and of the low molecular weight heparin reviparin (REVI) on ischemia/reperfusion (I/R) injury, acute rejection (AR) and chronic allograft nephropathy (CAN) in rats. Organs were harvested 5 days after 60 min of renal I/R injury. For investigation of AR and CAN we used the allogeneic Fisher-Lewis model. Kidneys were harvested at one respectively 32 weeks after transplantation. Rats were treated with either vehicle, LU or REVI. After I/R injury, treatment with REVI or LU reduced infiltration with MHC II and R73-positive cells, whereas only REVI reduced ED1-positive cells and expression of monocyte chemoattractant protein-1. There was no effect of REVI and LU on acute allograft rejection. Treatment with LU or REVI reduced glomerular infiltration with ED1 and MHCII-positive cells and renal expression of transforming growth factor-beta 32 weeks after transplantation. Only REVI treatment reduced albuminuria, interstitial infiltration and histological signs of CAN. LU, and in a more potent manner REVI, reduce signs of CAN and renal inflammation after I/R injury. Chemically modified heparins without anticoagulatory effects may offer a new treatment option in preventing I/R injury and CAN in human kidney transplantation.

In vivo effects of cyclic administration of 15-deoxyspergualin on leucocyte function in patients with Wegener's granulomatosis

15-Deoxyspergualin (DSG) is an alternative treatment modality for Wegener's granulomatosis (WG) patients refractory to conventional treatment. Nevertheless, it is unclear how DSG modulates disease activity in these patients. This study was conducted to investigate which parameters of adaptive and acquired immunity were influenced during two subsequent cycles of DSG treatment. Emphasis was put upon T cell and monocyte activation, neutrophil function and surface expression of proteinase-3 (PR-3). Anti-CD3/anti-CD28 and interleukin (IL)-15/IL-7-mediated T cell proliferation were assessed by fluorescence activated cell sorter (FACS) analysis using carboxyfluorescein succinimidyl ester (CSFE) labelling. Interferon (IFN)-gamma and IL-10 production were determined in the supernatants of these cultures by enzyme-linked immunosorbent assay. Monocyte activation was assessed in lipopolysaccharide (LPS)-stimulated whole blood, using tumour necrosis factor (TNF)-alpha as read-out. Neutrophil function was determined by measuring oxidative burst, chemotaxis and phagocytosis. T cell activation markers and PR3 expression were measured by FACS. All parameters were determined directly before and after each DSG cycle. Anti-CD3/anti-CD28-mediated T cell proliferation was reduced directly after DSG treatment. Directly before a subsequent cycle of DSG was started, T cell proliferation was increased. Similar findings were observed for IFN-gamma and IL-10 production by T cells. DSG did not influence IL-15/IL-7-mediated T cell proliferation. LPS-mediated TNF-alpha production was also impaired directly after DSG treatment. No influence on T cell activation markers, neutrophil function and surface PR-3 expression was observed in peripheral blood of these patients. Our data demonstrate that DSG influences T cell and monocyte activation in a reversible fashion. Although DSG causes neutropenia in these patients, it does not influence neutrophil function.

Comparison of early renal function parameters for the prediction of 5-year graft survival after kidney transplantation

BACKGROUND

Early graft function (EGF) has an enduring effect on the subsequent course after kidney transplantation. This study compares quantitative parameters of EGF for the prediction of graft survival.

METHODS

We involved 300 consecutive transplant recipients from deceased donors from 1989 to 2005. Urine output during 24 h post-transplant (UO), and serum creatinine after 1 week (Cr7) were taken for explanatory variables. We generated Kaplan-Meier (K-M) estimates of graft survival, by quintiles of the explanatory variable. Cox regression was applied to control for various recipient factors.

RESULTS

K-M survival estimates indicate a threshold effect of UO and Cr7, which can dissect the risk of graft failure. The thresholds referring to the 2nd quintile correspond to a UO >630 ml and a Cr7 <2.5 mg/dl and were associated with a proportional hazard ratio of 0.52 (95% CI 0.33-0.84) and 0.34 (95% CI 0.18-0.65), respectively. Combining both of the parameters predicted a 5-year graft survival probability >90%, according to a hazard ratio of 0.21 (95% CI 0.09-0.46). Requirement of dialysis post-transplant lost its discriminatory power and was not a significant explanatory variable in the multivariate analysis.

CONCLUSION

Routine parameters for monitoring of EGF display a threshold effect allowing accurate prediction of 5-year graft survival at the earliest point in time. The quantitative threshold levels for an optimum discriminatory power require validation in a larger, preferably multicentre database.

Life-threatening intoxication with methylene bis(thiocyanate): clinical picture and pitfalls. A case report

Background

Methylene bis(thiocyanate) (MBT) is a microbiocidal agent mainly used in industrial water cooling systems and paper mills as an inhibitor of algae, fungi, and bacteria.

Case presentation

We describe the first case of severe intoxication following inhalation of powder in an industrial worker. Profound cyanosis and respiratory failure caused by severe methemoglobinemia developed within several minutes. Despite immediate admission to the intensive care unit, where mechanical ventilation and hemodialysis for toxin elimination were initiated, multi-organ failure involving liver, kidneys, and lungs developed. While liver failure was leading, the patient was successfully treated with the MARS (molecular adsorbent recirculating system) procedure.

Conclusion

Intoxication with MBT is a potentially life-threatening intoxication causing severe methemoglobinemia and multi-organ failure. Extracorporeal liver albumin dialysis (MARS) appears to be an effective treatment to allow recovery of hepatic function.

Persistent T-cell activation and clinical correlations in patients with ANCA-associated systemic vasculitis

BACKGROUND

Although in antineutrophil cytoplasmic autoantibodies (ANCA)-associated systemic vasculitis (AASV) patients, activation of T-cells has been described, persistence of these alterations has not been well characterized. This study was conducted to define persistent T-cell activation (PTA) in AASV patients and to assess whether this correlates with disease activity, disease severity, age or therapy.

METHODS

The expression of CD4, CD45RO, CD25, CD26, CD28, CCR7 and HLA-DR was examined longitudinally in 38 consecutive AASV patients. Clinical parameters were compared by univariate and multiple analysis and Kaplan-Meier curves for relapse-free survival were calculated.

RESULTS

PTA could be defined as either of two activation phenotypes, i.e. a low percentage of CD4+ CD45RO- T-cells or a high percentage of CD25 in the naïve CD4+ population (n = 26), since only these phenotypes were stable over time and were not associated with active disease. In patients with PTA, major organ involvement was significantly more often found than in patients without PTA. Moreover, the cumulative cyclophosphamide dose (26.86 vs 8.53 P < 0.01) was significantly increased in these patients, suggesting that PTA was associated with disease severity. In general, patients with PTA were older than those without (62.92 +/- 9.4 years vs 48.42 +/- 16.9 years respectively, P < 0.01). PTA was independent of disease duration. Interestingly, patients with a low percentage of CD4+CD45RO- T-cells were significantly more often diagnosed as microscopic polyangiitis (P < 0.01).

CONCLUSION

We identified two independent phenotypes of T-cell activation in AASV patients. These phenotypes are persistent and do not reflect disease activity. PTA predominantly occurs in patients with severe disease. This might explain the higher cumulative cyclophosphamide dose found in these patients.

Serial ANCA determinations for monitoring disease activity in patients with ANCA-associated vasculitis: systematic review

BACKGROUND

Antineutrophil cytoplasmic antibodies (ANCAs) are considered by some investigators to be sensitive markers of disease activity and have been suggested to predict relapse and guide therapeutic decisions. Studies using serial ANCA monitoring in patients with ANCA-associated vasculitis (AASV) have yielded controversial results during the last 15 years. To assess the diagnostic value of serial ANCA testing in the follow-up of patients with AASV, we conducted a systematic review of the available literature.

METHODS

Studies were identified by a comprehensive search of the PubMed and BIOSIS+/RRM databases, as well as hand searching. Method quality of all eligible studies was assessed with respect to external and internal validity according to established criteria for diagnostic studies.

RESULTS

Twenty-two studies met our inclusion criteria, including a total of 950 patients. Whereas generalizability was not a major problem, assessment of internal validity showed that only a minority of studies reported the combination of consecutive patient recruitment, prospective data collection, and independent determination of both index and reference tests, considered as the ideal for diagnostic test studies. Quantitative meta-analytic calculations were not conducted because of the presence of considerable method heterogeneity.

CONCLUSION

The presence of considerable methodological heterogeneity combined with methodological shortcomings with respect to internal validity in the majority of included studies preclude firm conclusions from the available literature concerning the clinical value of serial ANCA determinations for monitoring the follow-up of patients with AASV.

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.

Abnormalities of CD4 T cell subpopulations in ANCA-associated vasculitis

In patients with ANCA-associated vasculitis (AAV), CD25 expression is increased on circulating T cells. Although in animal experiments the role of CD4(+) CD25(+) T-regulatory-cells (T(reg)) in protection against autoimmunity is well established, the role of these cells in AAV is unknown. To investigate the hypothesis that an increased expression of CD25 on T cells is related to persistent T cell activation and not to disturbances in T(reg) cells in AAV (34 patients, six of them after renal transplantation), we investigated CD25 expression in different subpopulations of CD4(+) cells and FOXP3 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). In addition, T cell proliferation and cytokine secretion after stimulation with anti-CD3 and anti-CD28 and intracellular cytokine production after stimulation with phorbol myristate acetate (PMA)-ionomycin was determined. Controls were non-vasculitic renal transplant patients (n = 9) and healthy controls (HC) (n = 13). In AAV the total number of lymphocytes, CD4(+) lymphocytes and the percentage of naive T cells are lower than in HC and RTX. An increased percentage of CD25(+) cells was found in AAV and AAV/RTX, irrespective of disease activity, but not in HC or RTX. This was confined to the naive (CD4(+) CD45RB(high)) population only. FOXP3 mRNA expression in CD4(+) T cells did not differ between AAV patients and healthy controls. In vitro T cell proliferation was enhanced in AAV patients compared to HC (P < 0.01). PBMC of AAV patients produced significantly less interleukin (IL)-10 and interferon (IFN)-gamma after anti-CD3/CD28 stimulation. The percentage of IL-10 and IL-12, but not IFN-gamma, IL-4 or tumour necrosis factor (TNF)-alpha-producing cells was significantly higher in patients compared to HC. These findings were confined to the memory population of CD4(+) cells. We conclude that AAV patients are lymphopenic and have low numbers of CD4(+) T cells, which seem to be in a persistent state of activation.

Prolonged treatment of refractory Wegener's granulomatosis with 15-deoxyspergualin: an open study in seven patients

BACKGROUND

A subset of patients with Wegener's granulomatosis does not respond to daily oral cyclophosphamide (CYC) plus corticosteroids or suffers from intolerable side effects. A 6 month course of the immunosuppressant 15-deoxyspergualin (DSG) has previously been employed successfully in these refractory cases. However, there are no reports on long-term treatment with DSG.

METHODS

To document the effects of prolonged DSG treatment, this study reports on seven patients suffering refractory Wegener's granulomatosis, who were successfully treated with DSG over an average of 26.5 months (range: 11-55.5 months).

RESULTS

Before administration of DSG, patients had experienced an average of 6.6 relapses (range: 3-12) under an average of 5.4 (range: 2-11) different therapeutic approaches, which included CYC in all cases. All suffered active disease when DSG was initiated. Four were unresponsive to CYC and three did not tolerate it. DSG (0.5 mg/kg/day subcutaneous) was given for 2-3 weeks until the leukocyte count dropped to 3000/microl, followed by a rest until a leukocyte count of 4000/microl was reached again. No other immunosuppressants besides corticosteroids were given. All patients showed a long-lasting, favourable response to DSG with complete (n = 5) or partial (n = 2) remission. Only one case relapsed while being treated with DSG. Termination/interruption of DSG was followed by relapse in four of five occasions. Resumption of DSG led to complete remission. Currently, five of the seven patients are still treated with DSG and are in remission. Infections, mainly of the respiratory tract, were observed in five cases and resolved after treatment. One case developed a third-degree heart block that required pacing.

CONCLUSIONS

In patients with refractory Wegener's granulomatosis, prolonged treatment with DSG seems safe and successful.

Trichosporon asahii infection of a dialysis PTFE arteriovenous graft

Trichosporon species are the causative agents of superficial skin infections, such as white piedra. Immunocompromised hosts, particularly those with underlying hematological malignancy, are at risk of developing invasive infection, which usually progresses to disseminated life-threatening disease. Peritonitis caused by Trichosporon has been described in end-stage renal disease patients treated with continuous ambulatory peritoneal dialysis. Here, we report on a Trichosporon infection of an arteriovenous graft in a patient on chronic hemodialysis. The infection was successfully treated with fluconazole and total surgical resection of the graft.

Treatment of proteinuria with low-molecular-weight heparin after renal transplantation

The development of nephrotic-range proteinuria after renal transplantation is an unfavourable prognostic factor for graft survival. In contrast to that in other nephropathies, the role of renin-angiotensin blockade in kidney transplantation is less well defined, and its anti-proteinuric effect is markedly reduced in the presence of segmental glomerulosclerosis. Here, we describe two patients who developed severe proteinuria after renal transplantation, despite effective blood pressure control with an ACE inhibitor. Histological changes were consistent with IgA-nephropathy and focal segmental glomerulosclerosis. Both patients were treated with low-molecular-weight heparin in addition to pre-existing ACE inhibition. This regimen led to a significant and long-lasting reduction of proteinuria. Our data suggest that low-molecular-weight heparin possesses strong renoprotective properties, thus confirming previous data from experimental nephropathies. This approach might represent a promising new strategy for treatment of proteinuria after kidney transplantation.

Impact of donor dopamine on immediate graft function after kidney transplantation

Optimizing medical donor management may have a considerable impact on transplantation outcome. This study investigated the effect of donor dopamine on initial graft function in renal allograft recipients, involving 254 consecutive recipients of a cadaver kidney, aged 18-74 years, transplanted between 1990 and 2003. Immunosuppression was based on cyclosporine. Patients were grouped according to donor use of dopamine during intensive care. Delayed graft function (DGF), and serial creatinine concentrations were compared between the groups. Dopamine-treated and -untreated donors were very similar regarding hemodynamics and renal function. Delayed graft function occurred in 47/158 treated and 48/96 untreated kidneys (p = 0.001). Donor dopamine was associated with a more rapid decrease of s-creatinine, which became obvious on the first postoperative day. Of patients in the treated and untreated group, respectively, 81.9% and 65.8% reached a s-creatinine level less than 2 mg/dL during the first month (p = 0.005). Donor dopamine remained predictive of a normalized s-creatinine level [HR 1.71; 95% CI 1.22-2.41] after controlling for confounding factors by multivariate Cox regression. Donor dopamine is associated with improvements of initial graft function after kidney transplantation. The beneficial effect of dopamine is achievable without side-effects for the recipients, and correlates with superior long-term graft survival.

Expression of somatostatin receptors in inflammatory lesions and diagnostic value of somatostatin receptor scintigraphy in patients with ANCA-associated small vessel vasculitis

OBJECTIVE

To assess the usefulness of somatostatin receptor (SSTR) scintigraphy for the evaluation of disease activity in the upper and lower respiratory tract in ANCA-associated vasculitis (AASV).

METHODS

Thirty-two consecutive patients with AASV were subjected to SSTR scintigraphy as part of their initial diagnostic evaluation and follow-up. The presence of SSTRs in inflammatory lesions was evaluated with immunohistochemistry in selected cases.

RESULTS

In AASV, specificity of SSTR scintigraphy for active vs non-active disease was 96% for pulmonary disease and 100% for ear, nose and throat (ENT) involvement, while sensitivity was 86% and 68%, respectively. Absence of previously present tracer accumulation characterized treatment responders, and treatment resistance was reflected by repeated positive scintigraphy. We could demonstrate the expression of SSTRs in lung and mucosal biopsies obtained from patients with active Wegener's granulomatosis and with microscopic polyangiitis.

CONCLUSION

SSTR scintigraphy is useful for the assessment of AASV, indicating disease activity, disease extent and treatment efficacy. SSTRs are expressed in both granulomatous as well as non-granulomatous AASV.

[Rapidly progressive glomerulonephritis:classification, pathogenesis and clinical management]

Rapidly progressive glomerulonephritides (RPGN) belong to a heterogeneous group of inflammatory kidney diseases which are commonly associated with systemic vasculitic syndromes. Renal histology is characterized by necrotizing lesions within the glomerual tuft and extracapillary proliferation, in most cases leading rapidly to renal failure. The etiology and pathogenesis are only partly elucidated. Since irreversible renal scaring develops within days to weeks, RPGN represent a nephrological emergency necessitating urgent diagnostic evaluation and rapid institution of effective therapy. New onset nephritic sediment combined with concomitantly deteriorating excretory renal function should lead to immediate nephrological consultation. Autoimmune serology and particularly renal biopsy are of the utmost importance for rapid diagnosis. Most forms of RPGN are treated with immunosuppressive regimens which generally consist of high dose steroids in combination with the alkylating agent cyclophosphamide. Some forms also require the use of plasma exchange therapy. Rapid diagnosis and early therapy improves both renal and overall outcome in the affected patients.

Acetylcysteine for prevention of contrast nephropathy: meta-analysis

BACKGROUND

Contrast nephropathy is associated with increased in-hospital morbidity and mortality and leads to extension of hospital stay in patients with chronic renal insufficiency. Acetylcysteine seems to be a safe and inexpensive way to reduce contrast nephropathy. We aimed to assess the efficacy of acetylcysteine to prevent contrast nephropathy after administration of radiocontrast media in patients with chronic renal insufficiency.

METHODS

We did a meta-analysis of randomised controlled trials comparing acetylcysteine and hydration with hydration alone for preventing contrast nephropathy in patients with chronic renal insufficiency. The trials were identified through a combined search of the BIOSIS+/RRM, MEDLINE, Web of Science, Current Contents Medizin, and The Cochrane Library Databases. We used incidence of contrast nephropathy 48 h after administration of radiocontrast media as an outcome measure.

FINDINGS

Seven trials including 805 patients were eligible according to our inclusion criteria and were analysed. Overall incidence of contrast nephropathy varied between 8% and 28%. Since significant heterogeneity was indicated by the Q statistics (p=0.016) we used a random-effects model to combine the data. Compared with periprocedural hydration alone, administration of acetylcysteine and hydration significantly reduced the relative risk of contrast nephropathy by 56% (0.435 [95% CI 0.215-0.879], p=0.02) in patients with chronic renal insufficiency. Meta-regression revealed no significant relation between the relative risk of contrast nephropathy and the volume of radiocontrast media administered or the degree of chronic renal insufficiency before the procedure.

INTERPRETATION

Compared with periprocedural hydration alone, acetylcysteine with hydration significantly reduces the risk of contrast nephropathy in patients with chronic renal insufficiency. The relative risk of contrast nephropathy was not related to the amount of radiocontrast media given or to the degree of chronic renal insufficiency before the procedure.

SCG/Kinjoh mice: a model of ANCA-associated crescentic glomerulonephritis with immune deposits

BACKGROUND

Spontaneous crescentic glomerulonephritis-forming/Kinjoh (SCG/Kj) mice spontaneously develop crescentic glomerulonephritis (CGN), systemic vasculitis, and perinuclear ANCA (pANCA), and have been suggested as an animal model for human antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AASV). Since no systematic serologic, immunohistologic, or structural evaluation had been performed thus far, we reinvestigated the development of ANCA and CGN in these mice.

METHODS

SCG/Kj mice were subjected to serologic and urinary analysis, as well as histologic evaluation of the kidneys by standard light, immunofluorescence, and electron microscopy at regular intervals during the course of the disease.

RESULTS

Perinuclear ANCA developed as early as the 6th week of life, increasing both in frequency and titer in up to 100% of animals at week 20. Crescent formation began at week 10 and peaked at week 16, maximally affecting 57% of glomeruli. Crescent formation was initiated by "activated" podocytes that formed cell bridges between tuft and Bowman's capsule. The typical picture of a diffuse immune complex nephritis was found in all animals as early as 8 weeks. Fluorescence intensity increased with age and became strongly positive for immunoglobulin (Ig)A, IgM, IgG, and C3 in the mesangium and along the peripheral capillary loops.

CONCLUSION

Although ANCAs were found in the majority of animals, the massive presence of glomerular immune deposits differed from the pauci-immune pattern found in human AASV, making this model not completely representative for human ANCA-associated CGN. However, the spontaneous and concomitant development of pANCA, small vessel vasculitis, and CGN raises the opportunity to analyze pathogenetic links between these disease manifestations in vivo.

Glomerular immune deposits are associated with increased proteinuria in patients with ANCA-associated crescentic nephritis

BACKGROUND

In small vessel vasculitis and its renal-limited form, idiopathic crescentic glomerulonephritis, renal damage is characterized by pauci-immune necrotizing crescentic glomerulonephritis (CGN) without histological evidence of immunoglobulin (Ig) deposition. In some patients, however, significant amounts of immune deposits may be detected. Therefore, we evaluated the clinical significance of these immune deposits in anti-neutrophil cytoplasmic autoantibody (ANCA)-associated pauci-immune CGN.

METHODS

Renal biopsies of 45 consecutive patients with new onset of Wegener's granulomatosis, microscopic polyangiitis and idiopathic CGN were retrospectively evaluated by light microscopy, immunohistochemistry and electron microscopy and the findings compared with renal function and outcome.

RESULTS

Typical pauci-immune CGN was found in 37 patients (group I). In eight patients (18%; group II), however, histopathological examination revealed substantial deposition of Ig in the mesangium and/or along the glomerular basement membrane. Five of these eight patients were cANCA positive; two initially had pANCA and developed a cANCA pattern and one was pANCA positive. There were no differences between groups in age, gender, renal function or extra-renal organ involvement at the time of biopsy. However, patients in group II had significantly more proteinuria (5.4+/-3.1 vs 1.3+/-1.0 g/24 h; P=0.016). We also observed a trend for a worse outcome with respect to renal function and mortality in group II patients; however, the differences did not reach significance.

CONCLUSIONS

Our results confirm that in ANCA-associated CGN a substantial percentage of patients have evidence of Ig deposition in renal biopsies. In this subgroup, Ig deposition was associated with a significantly greater degree of proteinuria. Further investigations are necessary to define the full clinical impact of immune-complex deposition on the clinical course of renal disease in pauci-immune CGN.