Effect of belimumab on proteinuria and anti-phospholipase A2 receptor autoantibody in primary membranous nephropathy

Background

Immunosuppressant drugs reduce proteinuria and anti-phospholipase A2 receptor autoantibodies (PLA2R-Ab) in primary membranous nephropathy (PMN) with varying success and associated toxicities. This study aimed to evaluate the effect of belimumab on proteinuria and PLA2R-Ab in participants with PMN.

Methods

In this prospective, open-label, experimental medicine study, 14 participants with PMN and persistent nephrotic-range proteinuria received up to 2 years belimumab monotherapy (10 mg/kg, every 4 weeks). Changes in proteinuria (urinary protein:creatinine ratio), PLA2R-Ab, albumin, cholesterol, B-cell subsets and pharmacokinetics were analysed during treatment and up to 6 months after treatment.

Results

Eleven participants completed to the primary endpoint (Week 28) and nine participants completed the study. In the intention-to-treat population population, baseline proteinuria of 724 mg/mmol [95% confidence interval (CI) 579–906] decreased to 498 mg/mmol (95% CI 383–649) and 130 mg/mmol (95% CI 54–312) at Weeks 28 and 104, respectively, with changes statistically significant from Week 36 (n = 11, P = 0.047). PLA2R-Ab decreased from 174 RU/mL (95% CI 79–384) at baseline to 46 RU/mL (95% CI 16–132) and 4 RU/mL (95% CI 2–6) at Weeks 28 and 104, respectively, becoming statistically significant by Week 12 (n = 13, P = 0.02). Nine participants achieved partial (n = 8) or complete (n = 1) remission. Participants with abnormal albumin and/or cholesterol at baseline gained normal/near normal levels by the last follow-up. Adverse events were consistent with those expected in this population.

Conclusions

Belimumab treatment in participants with PMN can reduce PLA2R-Ab and subsequently proteinuria, important preludes to remission induction.

Inhibition of ErbB kinase signalling promotes resolution of neutrophilic inflammation

Neutrophilic inflammation with prolonged neutrophil survival is common to many inflammatory conditions, including chronic obstructive pulmonary disease (COPD). There are few specific therapies that reverse neutrophilic inflammation, but uncovering mechanisms regulating neutrophil survival is likely to identify novel therapeutic targets. Screening of 367 kinase inhibitors in human neutrophils and a zebrafish tail fin injury model identified ErbBs as common targets of compounds that accelerated inflammation resolution. The ErbB inhibitors gefitinib, CP-724714, erbstatin and tyrphostin AG825 significantly accelerated apoptosis of human neutrophils, including neutrophils from people with COPD. Neutrophil apoptosis was also increased in Tyrphostin AG825 treated-zebrafish in vivo. Tyrphostin AG825 decreased peritoneal inflammation in zymosan-treated mice, and increased lung neutrophil apoptosis and macrophage efferocytosis in a murine acute lung injury model. Tyrphostin AG825 and knockdown of egfra and erbb2 by CRISPR/Cas9 reduced inflammation in zebrafish. Our work shows that inhibitors of ErbB kinases have therapeutic potential in neutrophilic inflammatory disease.

Chronic obstructive pulmonary disease (or COPD) is a serious condition that causes the lungs to become inflamed for long periods of time, leading to permanent damage of the airways.

Immune cells known as neutrophils promote inflammation after an injury, or during an infection, to aid the healing process. However, if they are active for too long, they may also cause tissue damage and drive inflammatory diseases including COPD. To limit damage to the body, neutrophils usually have a very short lifespan and die by a regulated process known as apoptosis. Finding ways to stimulate apoptosis in neutrophils may be key to developing better treatments for inflammatory diseases.

Cells contain many enzymes known as kinases that control apoptosis and other cell processes. Drugs that inhibit specific kinases are effective treatments for some types of cancer and other conditions, and new kinase-inhibiting drugs are currently being developed. However, it remains unclear which kinases regulate apoptosis in neutrophils or which kinase-inhibiting drugs may have the potential to treat COPD and other inflammatory diseases.

To address these questions, Rahman et al. tested over 350 kinase-inhibiting drugs to identify ones that promote apoptosis in neutrophils. The experiments showed that human neutrophils treated with drugs that inhibit the ErbB family of kinases died by apoptosis more quickly than untreated neutrophils. Next, Rahman et al. used zebrafish with injured tail fins as models to study inflammation. Zebrafish treated with one of these drugs – known as Tyrphostin AG825 – had lower levels of inflammation and their neutrophils underwent apoptosis more frequently than untreated zebrafish. Since drugs can have off-target effects, Rahman et al. went on to show using gene-editing technology that reducing the activity of two genes that encode ErbB kinases in zebrafish also decreased the levels of inflammation in the fish.

Further experiments used mice that develop inflammation in the lungs similar to COPD in humans. As expected, neutrophils in the lungs of mice treated with Tyrphostin AG825 underwent apoptosis more frequently than those in untreated mice. These dead neutrophils were effectively cleared by other immune cells called macrophages, which also helps limit damage caused by neutrophils.

Together, these findings show that Tyrphostin AG825 and other drugs that inhibit ErbB kinases help to reduce inflammation by promoting the death of neutrophils. Since several of these drugs are already used to treat human cancers, it may be possible in the future to repurpose them for use in people with COPD and other long-term inflammatory diseases. Determining whether this is possible is an aim for future studies.

Target engagement and cellular fate of otelixizumab: a repeat dose escalation study of an anti-CD3ε mAb in new-onset type 1 diabetes mellitus patients

AIMS

This paper describes the pharmacological findings from a study where otelixizumab, an anti-CD3ɛ mAb, was dosed in new onset Type 1 diabetes mellitus (NOT1DM) patients. This is the first time that the full dose-response of an anti-CD3ɛ mAb has been investigated in the clinic. The data have been validated using a previously developed pharmacokinetic/pharmacodynamic (PK/PD) model of otelixizumab to simulate the interplay between drug administration, CD3ɛ target engagement and downmodulation.

METHODS

Patients were randomized to control or active treatment with otelixizumab (1:4), administered via infusion over 6 days, in a dose-ascending study consisted of three cohorts (n = 10 per cohort) at doses of 9, 18 or 27 mg respectively. The study allowed quantification of otelixizumab PK, CD3ɛ target engagement and its pharmacodynamic effect (CD3ε/TCR modulation on circulating T lymphocytes).

RESULTS

Otelixizumab concentrations increased and averaged to 364.09 (54.3), 1625.55 (72.5) and 2781.35 (28.0) ng ml^-1 (Geom.mean, %CV) at the 9, 18 and 27 mg dose respectively. CD3ɛ target engagement was found to be rapid (within the first 30 min), leading to a receptor occupancy of ~60% within 6 h of dosing in all three doses. A dose-response relationship was observed with the two highest doses achieving a ~90% target engagement and consequential CD3ɛ/TCR downmodulation by Day 6.

CONCLUSIONS

Data from this study revealed maximum target engagement and CD3ɛ/TCR modulation is achieved at doses of 18, 27 mg of otelixizumab. These findings can be useful in guiding dose selection in clinical trials with anti-CD3ɛ mAbs.

Belimumab in kidney transplantation: an experimental medicine, randomised, placebo-controlled phase 2 trial

BACKGROUND

B cells produce alloantibodies and activate alloreactive T cells, negatively affecting kidney transplant survival. By contrast, regulatory B cells are associated with transplant tolerance. Immunotherapies are needed that inhibit B-cell effector function, including antibody secretion, while sparing regulators and minimising infection risk. B lymphocyte stimulator (BLyS) is a cytokine that promotes B-cell activation and has not previously been targeted in kidney transplant recipients. We aimed to determine the safety and activity of an anti-BLyS antibody, belimumab, in addition to standard-of-care immunosuppression in adult kidney transplant recipients. We used an experimental medicine study design with multiple secondary and exploratory endpoints to gain further insight into the effect of belimumab on the generation of de-novo IgG and on the regulatory B-cell compartment.

METHODS

We undertook a double-blind, randomised, placebo-controlled phase 2 trial of belimumab, in addition to standard-of-care immunosuppression (basiliximab, mycophenolate mofetil, tacrolimus, and prednisolone) at two centres, Addenbrooke's Hospital, Cambridge, UK, and Guy's and St Thomas' Hospital, London, UK. Participants were eligible if they were aged 18-75 years and receiving a kidney transplant and were planned to receive standard-of-care immunosuppression. Participants were randomly assigned (1:1) to receive either intravenous belimumab 10 mg per kg bodyweight or placebo, given at day 0, 14, and 28, and then every 4 weeks for a total of seven infusions. The co-primary endpoints were safety and change in the concentration of naive B cells from baseline to week 24, both of which were analysed in all patients who received a transplant and at least one dose of drug or placebo (the modified intention-to-treat [mITT] population). This trial has been completed and is registered with ClinicalTrials.gov, NCT01536379, and EudraCT, 2011-006215-56.

FINDINGS

Between Sept 13, 2013, and Feb 8, 2015, of 303 patients assessed for eligibility, 28 kidney transplant recipients were randomly assigned to receive belimumab (n=14) or placebo (n=14). 25 patients (12 [86%] patients assigned to the belimumab group and 13 [93%] patients assigned to the placebo group) received a transplant and were included in the mITT population. We observed similar proportions of adverse events in the belimumab and placebo groups, including serious infections (one [8%] of 12 in the belimumab group and five [38%] of 13 in the placebo group during the 6-month on-treatment phase; and none in the belimumab group and two [15%] in the placebo group during the 6-month follow-up). In the on-treatment phase, one patient in the placebo group died because of fatal myocardial infarction and acute cardiac failure. The co-primary endpoint of a reduction in naive B cells from baseline to week 24 was not met. Treatment with belimumab did not significantly reduce the number of naive B cells from baseline to week 24 (adjusted mean difference between the belimumab and placebo treatment groups -34·4 cells per μL, 95% CI -109·5 to 40·7).

INTERPRETATION

Belimumab might be a useful adjunct to standard-of-care immunosuppression in renal transplantation, with no major increased risk of infection and potential beneficial effects on humoral alloimmunity.

FUNDING

GlaxoSmithKline.

A distinct plasmablast and naïve B-cell phenotype in primary immune thrombocytopenia

Primary immune thrombocytopenia is an autoimmune disorder in which platelet destruction is a consequence of both B- and T-cell dysregulation. Flow cytometry was used to further characterize the B- and T-cell compartments in a cross-sectional cohort of 26 immune thrombocytopenia patients including antiplatelet antibody positive (n=14) and negative (n=12) patients exposed to a range of therapies, and a cohort of matched healthy volunteers. Markers for B-cell activating factor and its receptors, relevant B-cell activation markers (CD95 and CD21) and markers for CD4(+) T-cell subsets, including circulating T-follicular helper-like cells, were included. Our results indicate that an expanded population of CD95(+) naïve B cells correlated with disease activity in immune thrombocytopenia patients regardless of treatment status. A population of CD21-naïve B cells was specifically expanded in autoantibody-positive immune thrombocytopenia patients. Furthermore, the B-cell maturation antigen, a receptor for B-cell activating factor, was consistently and strongly up-regulated on plasmablasts from immune thrombocytopenia patients. These observations have parallels in other autoantibody-mediated diseases and suggest that loss of peripheral tolerance in naïve B cells may be an important component of immune thrombocytopenia pathogenesis. Moreover, the B-cell maturation antigen represents a potential target for plasma cell directed therapies in immune thrombocytopenia.

Rituximab versus cyclophosphamide in ANCA-associated renal vasculitis: 2-year results of a randomised trial

OBJECTIVES

The RITUXVAS trial reported similar remission induction rates and safety between rituximab and cyclophosphamide based regimens for antineutrophil cytoplasm antibody (ANCA)-associated vasculitis at 12 months; however, immunosuppression maintenance requirements and longer-term outcomes after rituximab in ANCA-associated renal vasculitis are unknown.

METHODS

Forty-four patients with newly diagnosed ANCA-associated vasculitis and renal involvement were randomised, 3:1, to glucocorticoids plus either rituximab (375 mg/m(2)/week×4) with two intravenous cyclophosphamide pulses (n=33, rituximab group), or intravenous cyclophosphamide for 3-6 months followed by azathioprine (n=11, control group).

RESULTS

The primary end point at 24 months was a composite of death, end-stage renal disease and relapse, which occurred in 14/33 in the rituximab group (42%) and 4/11 in the control group (36%) (p=1.00). After remission induction treatment all patients in the rituximab group achieved complete B cell depletion and during subsequent follow-up, 23/33 (70%) had B cell return. Relapses occurred in seven in the rituximab group (21%) and two in the control group (18%) (p=1.00). All relapses in the rituximab group occurred after B cell return.

CONCLUSIONS

At 24 months, rates of the composite outcome of death, end-stage renal disease and relapse did not differ between groups. In the rituximab group, B cell return was associated with relapse.

TRIAL REGISTRATION NUMBER

ISRCTN28528813.

Serum and glucocorticoid-regulated kinase 1 regulates neutrophil clearance during inflammation resolution

The inflammatory response is integral to maintaining health by functioning to resist microbial infection and repair tissue damage. Large numbers of neutrophils are recruited to inflammatory sites to neutralize invading bacteria through phagocytosis and the release of proteases and reactive oxygen species into the extracellular environment. Removal of the original inflammatory stimulus must be accompanied by resolution of the inflammatory response, including neutrophil clearance, to prevent inadvertent tissue damage. Neutrophil apoptosis and its temporary inhibition by survival signals provides a target for anti-inflammatory therapeutics, making it essential to better understand this process. GM-CSF, a neutrophil survival factor, causes a significant increase in mRNA levels for the known anti-apoptotic protein serum and glucocorticoid-regulated kinase 1 (SGK1). We have characterized the expression patterns and regulation of SGK family members in human neutrophils and shown that inhibition of SGK activity completely abrogates the antiapoptotic effect of GM-CSF. Using a transgenic zebrafish model, we have disrupted sgk1 gene function and shown this specifically delays inflammation resolution, without altering neutrophil recruitment to inflammatory sites in vivo. These data suggest SGK1 plays a key role in regulating neutrophil survival signaling and thus may prove a valuable therapeutic target for the treatment of inflammatory disease.

Optimized single pulse stimulation strategy for retinal implants

Retinal implants offer prospects of vision restoration for some blind patients by eliciting visual percepts of spots of light called 'phosphenes'. Recently, a mathematical model has been developed that predicts patients' perception of phosphene brightness for current-driven electrical stimulation of the retina. This model is explored for different stimulation parameters on a single electrode, including safety and hardware limitations, to produce phosphenes of specified brightness. We describe a procedure to derive stimulation parameters to account for such constraints, and describe methods to construct optimal stimuli in terms of producing maximal perceived brightness and efficient generation of phosphenes of a given brightness by employing minimal energy. In both cases, it is found that the resulting optimized stimulation waveforms consist of a long stimulation period, and interphase delays between initial and charge-balancing phases.

Genetically distinct subsets within ANCA-associated vasculitis

BACKGROUND

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a severe condition encompassing two major syndromes: granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis) and microscopic polyangiitis. Its cause is unknown, and there is debate about whether it is a single disease entity and what role ANCA plays in its pathogenesis. We investigated its genetic basis.

METHODS

A genomewide association study was performed in a discovery cohort of 1233 U.K. patients with ANCA-associated vasculitis and 5884 controls and was replicated in 1454 Northern European case patients and 1666 controls. Quality control, population stratification, and statistical analyses were performed according to standard criteria.

RESULTS

We found both major-histocompatibility-complex (MHC) and non-MHC associations with ANCA-associated vasculitis and also that granulomatosis with polyangiitis and microscopic polyangiitis were genetically distinct. The strongest genetic associations were with the antigenic specificity of ANCA, not with the clinical syndrome. Anti-proteinase 3 ANCA was associated with HLA-DP and the genes encoding α(1)-antitrypsin (SERPINA1) and proteinase 3 (PRTN3) (P=6.2×10(-89), P=5.6×10(-12,) and P=2.6×10(-7), respectively). Anti-myeloperoxidase ANCA was associated with HLA-DQ (P=2.1×10(-8)).

CONCLUSIONS

This study confirms that the pathogenesis of ANCA-associated vasculitis has a genetic component, shows genetic distinctions between granulomatosis with polyangiitis and microscopic polyangiitis that are associated with ANCA specificity, and suggests that the response against the autoantigen proteinase 3 is a central pathogenic feature of proteinase 3 ANCA-associated vasculitis. These data provide preliminary support for the concept that proteinase 3 ANCA-associated vasculitis and myeloperoxidase ANCA-associated vasculitis are distinct autoimmune syndromes. (Funded by the British Heart Foundation and others.).

Pulse versus daily oral cyclophosphamide for induction of remission in ANCA-associated vasculitis: long-term follow-up

INTRODUCTION

The previously reported randomised controlled trial of a consensus regimen of pulse cyclophosphamide suggested that it was as effective as a daily oral (DO) cyclophosphamide for remission induction of antineutrophil cytoplasm autoantibodies-associated systemic vasculitis when both were combined with the same glucocorticoid protocol (CYCLOPS study (Randomised trial of daily oral versus pulse Cyclophosphamide as therapy for ANCA-associated Systemic Vasculitis published de groot K, harper L et al Ann Int Med 2009)). The study had limited power to detect a difference in relapse. This study describes the long-term outcomes of patients in the CYCLOPS study.

METHODS

Long-term outcomes were ascertained retrospectively from 148 patients previously recruited to the CYCLOPS Trial. Data on survival, relapse, immunosuppressive treatment, cancer incidence, bone fractures, thromboembolic disease and cardiovascular morbidity were collected from physician records retrospectively. All patients were analysed according to the group to which they were randomised.

RESULTS

Median duration of follow-up was 4.3 years (IQR, 2.95-5.44 years). There was no difference in survival between the two limbs (p=0.92). Fifteen (20.8%) DO and 30 (39.5%) pulse patients had at least one relapse. The risk of relapse was significantly lower in the DO limb than the pulse limb (HR=0.50, 95% CI 0.26 to 0.93; p=0.029). Despite the increased risk of relapse in pulse-treated patients, there was no difference in renal function at study end (p=0.82). There were no differences in adverse events between the treatment limbs.

DISCUSSION

Pulse cyclophosphamide is associated with a higher relapse risk than DO cyclophosphamide. However, this is not associated with increased mortality or long-term morbidity. Although the study was retrospective, data was returned in 90% of patients from the original trial.

Anti-neutrophil cytoplasmic antibodies stimulate release of neutrophil microparticles

The mechanisms by which anti-neutrophil cytoplasmic antibodies (ANCAs) may contribute to the pathogenesis of ANCA-associated vasculitis are not well understood. In this study, both polyclonal ANCAs isolated from patients and chimeric proteinase 3-ANCA induced the release of neutrophil microparticles from primed neutrophils. These microparticles expressed a variety of markers, including the ANCA autoantigens proteinase 3 and myeloperoxidase. They bound endothelial cells via a CD18-mediated mechanism and induced an increase in endothelial intercellular adhesion molecule-1 expression, production of endothelial reactive oxygen species, and release of endothelial IL-6 and IL-8. Removal of the neutrophil microparticles by filtration or inhibition of reactive oxygen species production with antioxidants abolished microparticle-mediated endothelial activation. In addition, these microparticles promoted the generation of thrombin. In vivo, we detected more neutrophil microparticles in the plasma of children with ANCA-associated vasculitis compared with that in healthy controls or those with inactive vasculitis. Taken together, these results support a role for neutrophil microparticles in the pathogenesis of ANCA-associated vasculitis, potentially providing a target for future therapeutics.

ANCA-associated vasculitis is linked to carriage of the Z allele of α₁ antitrypsin and its polymers

BACKGROUND

Small studies have linked α1 antitrypsin (α1AT) deficiency to patients with antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV).

OBJECTIVE

To test the validity and the mechanism of this association between α1AT and AAV.

METHODS

The distribution of α1AT deficiency alleles Z and S was compared between 856 White Europeans with AAV and 1505 geographic and ethnically matched healthy controls. Genotyping was performed by allelic discrimination assay.

RESULTS

were compared between cases and controls using χ(2) tests. The serum and renal biopsies for α1AT polymers were compared using the polymer-specific 2C1 antibody. The role of α1AT polymers in promoting inflammation was investigated by examining their ability to prime neutrophils for ANCA activation as assessed by CD62L shedding, superoxide production and myeloperoxidase degranulation. Results The Z but not the S allele was over-represented in the patients compared with controls (HR=2.25, 95% CI 1.60 to 3.19). Higher concentrations of polymers of α1AT were detected in serum from patients carrying the Z allele than in those not carrying the Z allele (median (IQR) 1.40 (0.91-3.32) mg/dl vs 0.17 (0.06-0.28) mg/dl, p<0.001); polymers of α1AT were also seen in the renal biopsy of a patient with vasculitic glomerulonephritis. Polymers of α1AT primed neutrophils with CD62L shedding and increased superoxide production following ANCA activation. Carriage of the Z allele was not associated with disease severity, survival or relapse.

CONCLUSIONS

The Z but not the S deficiency allele is associated with AAV. Polymers of α1AT are present in the serum and glomeruli of at least some patients with the Z allele, which may promote inflammation through priming of neutrophils.

Mycophenolate mofetil vs azathioprine for remission maintenance in antineutrophil cytoplasmic antibody-associated vasculitis: a randomized controlled trial

CONTEXT

Current remission maintenance therapies for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are limited by partial efficacy and toxicity.

OBJECTIVE

To compare the effects of mycophenolate mofetil with azathioprine on the prevention of relapses in patients with AAV.

DESIGN, SETTING, AND PARTICIPANTS

Open-label randomized controlled trial, International Mycophenolate Mofetil Protocol to Reduce Outbreaks of Vasculitides (IMPROVE), to test the hypothesis that mycophenolate mofetil is more effective than azathioprine for preventing relapses in AAV. The trial was conducted at 42 centers in 11 European countries between April 2002 and January 2009 (42-month study). Eligible patients had newly diagnosed AAV (Wegener granulomatosis or microscopic polyangiitis) and were aged 18 to 75 years at diagnosis.

INTERVENTIONS

Patients were randomly assigned to azathioprine (starting at 2 mg/kg/d) or mycophenolate mofetil (starting at 2000 mg/d) after induction of remission with cyclophosphamide and prednisolone.

MAIN OUTCOME MEASURES

The primary end point was relapse-free survival, which was assessed using a Cox proportional hazards model. The secondary end points were Vasculitis Damage Index, estimated glomerular filtration rate, and proteinuria.

RESULTS

A total of 156 patients were assigned to azathioprine (n = 80) or mycophenolate mofetil (n = 76) and were followed up for a median of 39 months (interquartile range, 0.66-53.6 months). All patients were retained in the analysis by intention to treat. Relapses were more common in the mycophenolate mofetil group (42/76 patients) compared with the azathioprine group (30/80 patients), with an unadjusted hazard ratio (HR) for mycophenolate mofetil of 1.69 (95% confidence interval [CI], 1.06-2.70; P = .03). Severe adverse events did not differ significantly between groups. There were 22 severe adverse events in 13 patients (16%) in the azathioprine group and there were 8 severe adverse events in 8 patients (7.5%) in the mycophenolate mofetil group (HR, 0.53 [95% CI, 0.23-1.18]; P = .12). The secondary outcomes of Vasculitis Damage Index, estimated glomerular filtration rate, and proteinuria did not differ significantly between groups.

CONCLUSIONS

Among patients with AAV, mycophenolate mofetil was less effective than azathioprine for maintaining disease remission. Both treatments had similar adverse event rates.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00307645.

Delay of migrating leukocytes by the basement membrane deposited by endothelial cells in long-term culture

We investigated the migration of human leukocytes through endothelial cells (EC), and particularly their underlying basement membrane (BM). EC were cultured for 20 days on 3 μm-pore filters or collagen gels to form a distinct BM, and then treated with tumour necrosis factor-α, interleukin-1β or interferon-γ. Neutrophil migration through the cytokine-treated EC and BM was delayed for 20-day compared to 4-day cultures. The BM alone obstructed chemotaxis of neutrophils, and if fresh EC were briefly cultured on stripped BM, there was again a hold-up in migration. In studies with lymphocytes and monocytes, we could detect little hold-up of migration for 20-day versus 4-day cultures, in either the filter- or gel-based models. Direct microscopic observations showed that BM also held-up neutrophil migration under conditions of flow. Treatment of upper and/or lower compartments of filters with antibodies against integrins, showed that neutrophil migration through the endothelial monolayer was dependent on β₂-integrins, but not β1- or β₃-integrins. Migration from the subendothelial compartment was supported by β1- and β₂-integrins for all cultures, but blockade of β₃-integrin only inhibited migration effectively for 20-day cultures. Flow cytometry indicated that there was no net increase in expression of β1- or β3-integrins during neutrophil migration, and that their specific subendothelial function was likely dependent on turnover of integrins during migration. These studies show that BM is a distinct barrier to migration of human neutrophils, and that β₃-integrins are particularly important in crossing this barrier. The lesser effect of BM on lymphocytes and monocytes supports the concept that crossing the BM is a separate, leukocyte-specific, regulated step in migration.

Rituximab versus cyclophosphamide in ANCA-associated renal vasculitis

BACKGROUND

Cyclophosphamide induction regimens for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis are effective in 70 to 90% of patients, but they are associated with high rates of death and adverse events. Treatment with rituximab has led to remission rates of 80 to 90% among patients with refractory ANCA-associated vasculitis and may be safer than cyclophosphamide regimens.

METHODS

We compared rituximab with cyclophosphamide as induction therapy in ANCA-associated vasculitis. We randomly assigned, in a 3:1 ratio, 44 patients with newly diagnosed ANCA-associated vasculitis and renal involvement to a standard glucocorticoid regimen plus either rituximab at a dose of 375 mg per square meter of body-surface area per week for 4 weeks, with two intravenous cyclophosphamide pulses (33 patients, the rituximab group), or intravenous cyclophosphamide for 3 to 6 months followed by azathioprine (11 patients, the control group). Primary end points were sustained remission rates at 12 months and severe adverse events.

RESULTS

The median age was 68 years, and the glomerular filtration rate (GFR) was 18 ml per minute per 1.73 m(2) of body-surface area. A total of 25 patients in the rituximab group (76%) and 9 patients in the control group (82%) had a sustained remission (P=0.68). Severe adverse events occurred in 14 patients in the rituximab group (42%) and 4 patients in the control group (36%) (P=0.77). Six of the 33 patients in the rituximab group (18%) and 2 of the 11 patients in the control group (18%) died (P=1.00). The median increase in the GFR between 0 and 12 months was 19 ml per minute in the rituximab group and 15 ml per minute in the control group (P=0.14).

CONCLUSIONS

A rituximab-based regimen was not superior to standard intravenous cyclophosphamide for severe ANCA-associated vasculitis. Sustained-remission rates were high in both groups, and the rituximab-based regimen was not associated with reductions in early severe adverse events. (Funded by Cambridge University Hospitals National Health Service Foundation Trust and F. Hoffmann-La Roche; Current Controlled Trials number, ISRCTN28528813.)

Copy number, linkage disequilibrium and disease association in the FCGR locus

The response of a leukocyte to immune complexes (ICs) is modulated by receptors for the Fc region of IgG (FcγRs), and alterations in their affinity or function have been associated with risk of autoimmune diseases, including systemic lupus erythematosus (SLE). The low-affinity FcγR genomic locus is complex, containing regions of copy number variation (CNV) which can alter receptor expression and leukocyte responses to IgG. Combined paralogue ratio tests (PRTs) were used to distinguish three intervals within the FCGR locus which undergo CNV, and to determine FCGR gene copy number (CN). There were significant differences in FCGR3B and FCGR3A CNV profiles between Caucasian, East Asian and Kenyan populations. A previously noted association of low FCGR3B CN with SLE in Caucasians was supported [OR = 1.57 (1.08–2.27), P = 0.018], and replicated in Chinese [OR = 1.65 (1.25–2.18), P = 4 × 10⁻⁴]. There was no association of FCGR3B CNV with vasculitis, nor with malarial or bacterial infection. Linkage disequilibrium (LD) between multi-allelic FCGR3B CNV and SLE-associated SNPs in the FCGR locus was defined for the first time. Despite LD between FCGR3B CNV and a variant in FcγRIIB (I232T) which abolishes inhibitory function, both reduced CN of FCGR3B and homozygosity of the FcγRIIB-232T allele were individually strongly associated with SLE risk. Thus CN of FCGR3B, which controls IC responses and uptake by neutrophils, and variations in FCGR2B, which controls factors such as antibody production and macrophage activation, are important in SLE pathogenesis. Further interpretations of contributions to pathogenesis by FcγRs must be made in the context of LD involving CNV regions.

Prediction of ESRD in pauci-immune necrotizing glomerulonephritis: quantitative histomorphometric assessment and serum creatinine

Background

Clinical and pathologic features that predict outcome have important potential application in patients with pauci-immune necrotizing glomerulonephritis (usually antineutrophil cytoplasmic antibody–associated vasculitis). This study examines the predictive value of simple quantitative renal histologic measurements in a large cohort with extended follow-up.

Study Design

Cohort study.

Setting & Participants

390 consecutive patients with pauci-immune necrotizing glomerulonephritis at a single hospital (1983-2002); 90 patients underwent repeated kidney biopsy during follow-up.

Predictors

Age and serum creatinine concentration at biopsy, antineutrophil cytoplasmic antibody specificity, percentage of normal glomeruli, percentage of glomeruli with active lesions, and index of chronic damage (quantitative measurement of established cortical damage) in the initial kidney biopsy for all patients. The same factors were assessed in both biopsy specimens for patients undergoing an additional biopsy.

Outcomes & Measurements

End-stage renal disease and patient survival.

Results

Mortality at 1 and 5 years was 23% and 40%, respectively: standardized mortality ratio, 4.74 (95% CI, 3.62-6.32). End-stage renal disease was reached by 14% and 18% at 1 and 5 years, respectively. In multivariable analysis, serum creatinine level at biopsy and percentage of normal glomeruli in the initial biopsy specimen were the best predictors of kidney survival. C Statistics were 0.80 for creatinine level alone and 0.83 for creatinine level with normal glomeruli. In patients undergoing an additional biopsy, rapid progression in the index of chronic damage and serum creatinine level at the second biopsy were associated with kidney survival in multivariable analysis.

Limitations

Retrospective analysis. External validity of the index of chronic damage requires further assessment. Selection bias may influence repeated biopsy analyses.

Conclusions

Serum creatinine level at biopsy best predicts kidney survival in patients with pauci-immune necrotizing glomerulonephritis overall.

The role of capillary density, macrophage infiltration and interstitial scarring in the pathogenesis of human chronic kidney disease

To assess the relationship between interstitial capillary density and interstitial macrophages we prospectively measured these factors in situ in 110 patients with chronic kidney disease. Macrophage numbers and urinary MCP-1/CCL2 levels significantly correlated inversely with capillary density which itself significantly correlated inversely with chronic damage and predicted disease progression. In 54 patients with less than 20% chronic damage, there was a significant correlation between the urinary albumin to creatinine ratio and MCP-1/CCL2, and MCP-1/CCL2 and macrophages but not between MCP-1/CCL2 and capillary density. Conversely, in 56 patients with over 20% chronic damage there was no correlation between MCP-1/CCL2 and macrophages but there were significant inverse correlations between capillary density and both macrophages and chronic damage. The expression of VEGF mRNA significantly correlated with macrophage infiltration, capillary density and chronic scarring. In an ischemic-hypertensive subgroup there was upregulation of the hypoxia marker carbonic anhydrase IX and with over 20% chronic damage an increased macrophage to CCR2 ratio. Our study shows that proteinuria and MCP-1/CCL2 are important for macrophage recruitment in early disease. As renal scarring evolves, alternative pathways relating to progressive tissue ischemia secondary to obliteration of the interstitial capillary bed predominate.

Specific immunoabsorption

Rapidly progressive glomerulonephritis occurs in patients developing autoantibodies to the glomerular basement membrane (GBM) and in multisystem vasculitic syndromes such as Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA). In anti-GBM disease the pathogenicity of the autoantibodies has been established by transfer experiments; new solid-phase radioimmunoassays (RIAs) for circulating autoantibodies allow early diagnosis and effective monitoring of treatment. Sequential measurements of antibody levels showed that their generation is self-limiting (even without treatment) and that their production can be arrested more quickly with immunosuppressive therapy (cyclophosphamide and high dose steroids) together with intensive plasma exchange. In systemic vasculitis, no pathogenic agent has been identified and the diseases are rarely self-remitting. In WG, antibodies to cytoplasmic components of normal human neutrophils (and monocytes) were reported to be detectable by indirect immunofluorescence, with titres correlating with disease activity. We confirmed this and showed that antigen can be extracted from normal human neutrophils and used as ligand in a solid-phase RIA. Sera from patients with other forms of systemic vasculitis, such as MPA, as well as WG, are positive in this assay. The antigens have been further characterized by HPLC fractionation on a Toyosoda TSK gel filtration column. In WG, antibodies were directed towards cytoplasmic fractions of 100, 6 and 2 kDa; in MPA, antibody reacted only with the 100 kDa fraction. These findings suggest a humoral pathogenesis in these disorders and indicate that this approach may be helpful in the classification, diagnosis and monitoring of therapy in the systemic vasculitides. Further characterization of the autoantigen and its potential use in specific immunoabsorption are discussed.

Meta-analysis of myeloperoxidase G-463/A polymorphism in anti-neutrophil cytoplasmic autoantibody-positive vasculitis

Wegener's granulomatosis, microscopic polyangiitis and Churg Strauss syndrome are small-vessel vasculitides associated with anti-neutrophil cytoplasmic antibodies (ANCA) directed against proteinase 3 (PR3) and myeloperoxidase (MPO). A G to A polymorphism at position 463 in the promoter region of the MPO gene, which leads to the loss of a SP1 transcription binding site in an Alu hormone responsive element, reduces MPO expression. We hypothesized that MPO alleles may play a role in determining disease susceptibility or severity in ANCA-associated vasculitis (AASV). MPO genotypes were determined by restriction fragment length polymorphism polymerase chain reaction (RFLP/PCR) in 134 Caucasian patients (Wegener's granulomatosis, n = 69; microscopic polyangiitis, n = 65; PR3-ANCA n = 91; MPO-ANCA, n = 43) and 150 matched healthy controls. There was no difference in survival to renal failure or death in patients with the different MPO alleles (chi(2) = 0.904, P = 0.6362) or in presenting serum creatinine concentration based on MPO genotype (chi(2) = 0.389, P = 0.8232). There was no significant difference in genotype frequencies between controls (13AA, 102GG, 35GA) and patients (14AA, 97GG, 23GA: chi(2) = 1.75, P = 0.417), patients with Wegener's granulomatosis (5AA, 53GG, 11GA: chi(2) = 1.864, P = 0.3938) or patients with microscopic polyangiitis (9AA, 44GG, 12GA: chi(2) = 1.682, P = 0.4317). A meta-analysis of our study and two previous studies showed that there was no association between the myeloperoxidase G-463/A polymorphism and the risk of developing ANCA-associated vasculitis; GG versus GA plus AA (odds ratio 1.14; 95% confidence interval 0.86-1.50). The MPO G-463/A polymorphism is not a risk factor for the development or severity of AASV.

Recurrences and Infections During Continuous Immunosuppressive Therapy After Beginning Dialysis in ANCA-Associated Vasculitis

BACKGROUND

Approximately 20% of patients with antineutrophil cytoplasm antibody-associated systemic vasculitis (AASV) develop end-stage renal failure (ESRF). It is not clear whether continuation of immunosuppression, with its associated risks, is beneficial because relapse rates after the development of ESRF are reported to be low.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

Single tertiary-care referral center. 46 patients with AASV who developed ESRF from 1971 to 2004.

OUTCOMES & MEASUREMENTS

Treatment, relapse rates before and after dialysis therapy, patient outcome after dialysis therapy, and infection (defined as admission to hospital or intravenous antibiotics) were recorded.

RESULTS

Patients with AASV on dialysis therapy had 1- and 5-year survival rates of 82% and 55%, equivalent to current 1- and 5-year survival rates of dialysis patients reported by the UK renal registry, respectively. Infection rates in patients with ESRF were high in those with AASV on dialysis therapy; 106 events in 35 patients (dialysis patients with AASV, 0.89 infections/patient-year; confidence interval [CI], 0.74 to 1.08). Eight of 9 patients who died of infection were receiving immunosuppressive therapy. No patient died of active disease. Relapse rates after dialysis commencement were less than those predialysis (6 relapses in 4 patients; 0.05 relapses/patient-year postdialysis; CI, 0.02 to 0.1 compared with 18 relapses in 11 patients; 0.13 relapses/patient-year predialysis; CI, 0.07 to 0.19).

LIMITATIONS

This is a retrospective study spread over 3 decades with no control group.

CONCLUSIONS

Patients with AASV and ESRF are less likely to experience relapse than before dialysis therapy. Patients with AASV on dialysis therapy have a high rate of infection. These results may not be applicable to patients with pulmonary involvement.

Pathogenic mechanisms of anti-neutrophil cytoplasm antibody-associated vasculitis

Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitides are rare autoimmune diseases that can often be life threatening. They particularly affect the kidneys and lungs but can also affect many other organs. Various hypotheses have been proposed to explain the loss of tolerance against ANCA antigens (present in granules of neutrophils and monocytes); however, clear mechanisms remain elusive. Clinical observation, in vitro studies and newly developed animal models implicate ANCAs in disease pathogenesis and relevant mechanisms are now being characterized. Abnormalities in patient's T-cell populations exist and the increasingly recognized role of B cells in ANCA-associated vasculitis is also discussed.

ANCA-associated vasculitis: new options beyond steroids and cytotoxic drugs

Small vessel vasculitic syndromes--Wegener's granulomatosis, microscopic polyangiitis and renal limited vasculitis (which are associated with circulating antineutrophil cytoplasmic autoantibodies)--are an important cause of renal failure. Present immunosuppressive regimens that are based on cyclophosphamide have significantly increased survival rates. However, these treatments are toxic, increase the risk of infection and do not cure disease. Therefore, newer approaches are required. Understanding disease pathogenesis has allowed rational use for newer therapies such as rituximab, which depletes B cells. Unfortunately, blockade of promising targets such as TNF-alpha, which was thought to be a pivotal cytokine in inflammation, has not shown benefit in a randomised controlled trial. Better understanding of the pathogenesis of the disease is the key to the development of novel targeted therapies, which are urgently required to improve patient prognosis. Gene therapy with targeted delivery of specific proteins is an exciting future prospect.

The relationship between albuminuria, MCP-1/CCL2, and interstitial macrophages in chronic kidney disease

Glomerular-derived proteins may activate tubular cells to express the macrophage-directed chemokine monocyte chemoattractant protein-1 (MCP-1/CCL2). Macrophages at interstitial sites have a central role in directing renal scarring. We have prospectively assessed the relationship between albuminuria, urinary MCP-1/CCL2, interstitial macrophage infiltration, in situ damage, and clinical outcomes in a large group of patients with chronic kidney disease. We studied 215 patients and quantified albumin-creatinine ratio (ACR), urinary MCP-1/CCL2, interstitial macrophage numbers, and in situ damage. ACR correlated with urinary MCP-1/CCL2 (correlation 0.499; P<0.001), interstitial macrophage numbers (correlation 0.481; P<0.001), and index of chronic damage (correlation 0.363; P<0.001). Macrophage numbers closely correlated with in situ damage (correlation 0.755; P<0.001). By multivariate analysis ACR, urinary MCP-1/CCL2, and interstitial macrophage numbers were interdependent. By Kaplan-Meier survival analysis albuminuria, urinary MCP-1/CCL2, interstitial macrophages, and chronic damage predict the outcome. ACR, macrophage numbers, chronic damage, and creatinine independently predicted renal survival. The association of ACR with other variables was strongest in patients with less advanced disease states. There is a close association between albuminuria, urinary MCP-1/CCL2, and interstitial macrophage infiltration with in situ damage and clinical outcomes. These findings support the hypothesis that albuminuria triggers tubular MCP-1/CCL2 expression with subsequent macrophage infiltration. These processes may represent the dominant pathway for the progression of renal injury before the establishment of advanced renal scarring.

Anti-endothelial cell antibodies from lupus patients bind to apoptotic endothelial cells promoting macrophage phagocytosis but do not induce apoptosis

OBJECTIVE

Anti-endothelial cell antibodies (AECA) have been reported to induce apoptosis. We investigated the induction of apoptosis by these autoantibodies and their involvement in the removal of apoptotic cells.

METHODS

AECA isolated from patients with active systemic lupus erythematosus (SLE) were incubated with human umbilical vein endothelial cells (HUVECs). AECA-positive sera were identified using a cell-based ELISA. Apoptosis was measured by morphology and phosphatidylserine externalization using flow cytometry with fluorescein isothiocyanate (FITC)-conjugated annexin V. Flow cytometry was used to investigate AECA binding to apoptotic cells using FITC-conjugated anti-human immunoglobulin G (IgG). Apoptotic endothelial cells were stained with a red dye (PKH26) and co-cultured with macrophages, and phagocytosis was visualized under phase contrast microscopy.

RESULTS

AECA from patients with SLE did not induce apoptosis compared with normal IgG (nIgG) at any time point, as assessed by morphology (at 24 h, P = 0.167) or phosphatidylserine externalization (at 24 h, P = 0.098). However, there was increased binding of AECA to apoptotic endothelial cells (48.8 +/- 11.9 compared with 25.8 +/- 6.7% AECA binding to freshly isolated cells, P< 0.001). These opsonized endothelial cells showed greater phagocytosis by macrophages (mean phagocytic index 24.9 +/- 4.5%) when cells opsonized with nIgG were compared with AECA (34.8 +/- 3.4% n = 5, P = 0.01).

CONCLUSION

In conclusion, AECA bind to apoptotic endothelial cells but do not induce endothelial cell apoptosis. Macrophage phagocytosis is increased by opsonization of apoptotic endothelial cells by AECA, a proinflammatory mechanism of cell removal.

Impairment of lung function, health status and functional capacity in patients with ANCA-associated vasculitis

OBJECTIVE

To determine the effects of lung involvement on respiratory function in patients with ANCA-associated vasculitis and the relation to impaired health status.

METHODS

Thirty patients with ANCA-associated vasculitis in remission (15 with lung involvement at diagnosis as determined by an abnormal chest X-ray) were examined. We measured lung function, skeletal muscle strength [quadriceps force (QF), respiratory muscle strength (Pi(max))], exercise capacity (VO(2) peak) using treadmill exercise tests, and health status using the Short Form 36 and St George's respiratory questionnaires.

RESULTS

Exercise capacity was reduced compared with predicted values (58.2%, range 23-123%) and 18 patients showed functional aerobic impairment. Respiratory muscle function was reduced (72.1% predicted, range 20-108%) and was not related to lung involvement or steroid usage. Transfer factor correlated significantly with exercise capacity, suggesting inadequate delivery of oxygen to muscles. Nine patients had reduced transfer factor (seven with lung involvement). Patients with lung involvement had impaired gas transfer compared with those without lung involvement (96.9 +/- 6 vs 113.3 +/- 4.7% predicted, P = 0.04). However, there were significant abnormalities in other lung function parameters not related to previous lung involvement (eight patients had reduced forced expiratory volume in 1 s, and five patients had reduced residual volume). Twelve patients (five with previous lung involvement) had obstructive airways disease. Physical health status was impaired to a greater degree than mental health status across the whole group and was not related to lung involvement or original disease severity, but correlated with transfer factor.

CONCLUSION

Patients with ANCA-associated disease may have significant lung function impairment irrespective of lung involvement at the time of diagnosis. Patients showed reduced respiratory muscle strength, health status and exercise capacity, which correlated with reduced transfer factor.

ANCA-associated renal vasculitis at the end of the twentieth century--a disease of older patients

OBJECTIVE

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides are increasingly recognized in older patients. However, it is unknown whether disease presentation and response to treatment differs from younger patients. We aimed to examine the presentation, response to treatment and outcome of patients over 65 yr of age compared with a younger cohort.

METHODS

This retrospective, single centre, sequential cohort study reports presenting features and outcome of 233 consecutive new patients with ANCA-associated vasculitis between 1990 and 2000.

RESULTS

The median age of all patients was 65 yr (range 16-90 yr). Older patients (>65 yr) presented with more severe renal involvement at presentation (P < 0.001). Older patients were as likely to respond to treatment or undergo relapse as the younger patients. Older patients receiving immunosuppression had an increased risk of infection (P = 0.0027). Survival was worse in the older group (P = 0.016) and death occurred early. Mortality was associated with poor renal function (creatinine >400 micromol/l), infection and low serum albumin. Leucopenia was associated with severe renal impairment (P = 0.0048) and increased risk of infection (P = 0.0006). Multivariate analysis determined that serum creatinine >400 micromol/l and age were independent risk factors for poor prognosis.

CONCLUSION

ANCA-associated vasculitis occurs frequently in older patients and physicians should maintain a high index of suspicion. Older patients have a poorer prognosis due to more severe renal involvement and increased sensitivity to adverse effects of treatment. This study highlights the importance of careful dosing of cyclophosphamide: in those aged over 65 yr a 25% dose reduction is safe and reduces the risk of leucopenia. This study further highlights the importance of renal function on prognosis and the need for less toxic treatment regimens.

An interferon-gamma ELISPOT and immunohistochemical investigation of cytotoxic T lymphocyte-mediated tumour immunity in patients with paraneoplastic cerebellar degeneration and anti-Yo antibodies

Eight patients with paraneoplastic cerebellar degeneration (PCD) and anti-Yo antibodies were investigated to determine whether there is any association between cytotoxic T lymphocyte (CTL) responses reactive with two previously defined Yo-derived, HLA-A2.1 restricted epitopes (cdr2-1 and cdr2-2) and the presence of tumour-infiltrating CD8+ CTLs. cdr2-1 and cdr2-2-specific CTL responses could not be detected in 5 HLA-A2.1(+) patients in an ex vivo interferon-gamma ELISPOT assay and only 2/9 tumour sections contained CD8(+) intratumoural lymphocytes suggesting a very limited role for CTL-mediated tumour immunity in this patient group, all of whom had evidence of widespread malignancy at the time of diagnosis and/or death.

The importance of resolution of inflammation in the pathogenesis of ANCA-associated vasculitis

The primary small-vessel systemic vasculitides are disorders that target small blood vessels, inducing vessel wall inflammation, and are associated with the development of anti-neutrophil cytoplasmic antibodies. Multiple organs are attacked, including the lungs and kidneys. Increasing knowledge of pathogenesis suggests that the antibodies activate neutrophils inappropriately, leading to endothelial and vascular damage. Cytokines, such as tumour necrosis factor, can facilitate damage by priming the neutrophils and activating endothelial cells. Apoptosis of infiltrating neutrophils is also disrupted by anti-neutrophil cytoplasmic antibody activation, and removal of these effete cells occurs in a pro-inflammatory manner, promoting persistent inflammation. The autoimmune response may be promoted by aberrant phagocytosis of apoptotic neutrophils by dendritic cells. Understanding the pathogenesis can help to rationalize existing therapies and indicate new approaches to therapy.

Propylthiouracil and carbimazole associated-antineutrophil cytoplasmic antibodies (ANCA) in patients with Graves' disease

OBJECTIVE

Propylthiouracil treatment of Graves' disease has been postulated to provoke antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. We aimed to investigate whether carbimazole therapy was also associated with increased risk of ANCA.

DESIGN

The occurrence of ANCA and the relationship to thionamide treatment was investigated in a cross-sectional study in a consecutive series of 407 patients' with Graves' disease, 200 with Hashimoto's thyroiditis and 649 normal euthyroid subjects.

MEASUREMENTS

ANCA was measured by indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assay (ELISA) for proteinase 3 and myeloperoxidase-ANCA.

RESULTS

The prevalence of ANCA, as measured by IIF, was increased in the Graves' disease cohort (19.9%) compared with euthyroid controls (4.6%; P < 0.001). The prevalence of MPO-ANCA (measured by ELISA) was also increased in Graves' disease (P = 0.019). ANCA prevalence was more strongly associated with propylthiouracil treatment than carbimazole (P = 0.0265), although risk of ANCA was also higher in Graves' patients treated with carbimazole than controls (RR 2.2, P < 0.0001). ANCA positivity was not increased in patients with Hashimoto's thyroiditis.

CONCLUSION

This study revealed a high prevalence of ANCA in treated patients with Graves' disease but not in those with Hashimoto's thyroiditis. Furthermore, within the Graves' disease population, ANCA development was associated with propylthiouracil usage to a greater extent than carbimazole. These findings suggest that the altered immune environment associated with autoimmune thyroid disease is not sufficient to develop ANCA but treatment with thionamides is important in promoting ANCA development.

New developments in the pathogenesis of ANCA-associated vasculitis

In recent years there have been substantial developments in the understanding of the pathogenesis of ANCA-associated vasculitidies. Animal models have now been developed that finally prove a direct pathogenic role for ANCA, a subject fiercely debated since their original identification. We are also closer to understanding how ANCA exert their effects to cause disease. Progress has been made in elucidating how ANCA activate neutrophils, from how they bind antigen and where that antigen is located, to how antigen binding is translated into intracellular activity. The effects of ANCA activation on the effector functions of neutrophils and monocytes are being further dissected and the flow-based assay is allowing interactions with endothelium to be studied in more detail. Knowledge of the role of T cells has been enhanced by examining contributions to disease by differing subsets and their cytokine secretions. Defects in apoptosis playing a role in the initiation of other autoimmune diseases has prompted investigations into whether a similar pathogenesis is relevant in vasculitis, and various genetic polymorphisms have been discovered to be important in determining in whom vasculitis develops. This article reviews how recent research has helped in the understanding of the pathogenesis of small vessel vasculitis.

Antineutrophil cytoplasmic antibodies stabilize adhesion and promote migration of flowing neutrophils on endothelial cells

OBJECTIVE

Recruitment of neutrophils to sites of inflammation requires coordinated regulation of their capture, activation, and migration on vascular endothelium. This study examines whether exposure of neutrophils to antineutrophil cytoplasmic antibodies (ANCAs) can disrupt this sequence of events.

METHODS

Isolated human neutrophils were perfused in the presence or absence of ANCA-positive IgG over endothelial cells that had been activated with either 2 units/ml or 100 units/ml of tumor necrosis factor alpha (TNFalpha) for 4 hours.

RESULTS

When endothelial cells were activated with 100 units/ml of TNFalpha, neutrophils were captured from flow, a small proportion of adherent cells rolled, and the majority transmigrated through the endothelial cell monolayer. When neutrophils were treated with ANCA IgG immediately before, 5 minutes before, or 15 minutes before perfusion, none rolled on contact with the endothelium, but the majority still transmigrated. When endothelial cells were activated with 2 units/ml of TNFalpha, the majority of untreated adherent neutrophils rolled, a few transmigrated, and the number that attached decreased with time during washout. In contrast, when neutrophils were pretreated with ANCA IgG just before perfusion, adhesion was stabilized, and the number of neutrophils that transmigrated was increased 10-fold. Priming of the neutrophils with TNFalpha before the addition of ANCA further increased the stability of neutrophil binding, but did not significantly increase transmigration.

CONCLUSION

Rather than frustrating the transmigration process, ANCAs promoted the migration of neutrophils through the endothelium. That the effect was evident at a relatively low level of endothelial activation suggests that ANCAs may potentiate the early vasculitic lesion and promote tissue damage and recruitment of other proinflammatory cells.

Leukocyte-endothelial interactions in antineutrophil cytoplasmic antibody-associated systemic vasculitis

The etiology of ANCA-associated vasculitis is unknown. Currently, it is believed that disease may be triggered by infection with the release of proinflammatory cytokines in genetically susceptible individuals. Priming of PMNs and endothelial cells by these cytokines allows ANCAs to activate PMNs, with damage localized to the endothelium, resulting in early lesions. Damage and activation of endothelial cells produces proinflammatory chemokines and cytokines with influxes of monocytes and T cells that intensify endothelial damage. In the kidney, these changes eventually lead to crescent formation. Antigen-specific memory T cells persist after disease remission with the potential of reactivation and disease relapse. Although our understanding of the pathophysiologic mechanisms of ANCA-associated vasculitis is far greater now than when ANCAs were first identified in 1982, more experimental work in combination with clinical observations is required to further elucidate these mechanisms.

The value of pulse cyclophosphamide in ANCA-associated vasculitis: meta-analysis and critical review

BACKGROUND

The study aimed at studying efficacy and adverse effects of pulse cyclophosphamide (pCyc) treatment and to compare it to continuous cyclophosphamide (cCyc) for induction of remission in ANCA-associated vasculitides from data in the published literature.

METHODS

A Medline search identified 14 studies, containing more than five patients. From the 11 non-randomized studies, data on outcome following pCyc treatment were extracted. Results were given as fraction of the number of evaluable patients. A meta-analysis was performed on the three prospective, randomized controlled trials to compare outcomes concerning remission, relapses, infection, leucopenia, death and renal failure in patients treated with pCyc as opposed to cCyc.

RESULTS

The 11 non-randomized studies comprised 202 patients receiving pCyc. Cyc pulses of 375-1000 mg/sqm/pulse were applied at weekly to monthly intervals with different concomitant prednisolone regimens and variable adjunctive therapy. Complete remission was achieved in 112/191, partial remission in 23/191 evaluable patients. Relapses occurred in 68/135 patients, 40/115 patients were non-responders. Leucopenia, infections, haemorrhagic cystitis, and deaths were rare. The meta-analysis, comprising 143 patients, showed that pCyc compared with cCyc treatment was significantly less likely to fail to induce remission (OR 0.29; 95% CI 0.12-0.73) and had a significantly lower risk of infection (OR 0.45; 95% CI 0.23-0.89) and leucopenia (OR 0.36; 95% CI 0.17-0.78). Relapses occurred slightly, although not statistically significantly, more often under pCyc treatment (OR 1.79; 95% CI 0.85-3.75). There were no differences in end-stage renal failure or deaths between the two regimens.

CONCLUSIONS

The currently available, rather sparse data show that pCyc is less toxic than cCyc therapy and is an at least equally potent inductor of remission, but possibly at the expense of a higher relapse rate. The existing data do not give sufficient information on outcomes as time to remission and relapse, irreversible damage or quality of life without which a treatment regimen cannot satisfactorily be evaluated today. A large prospective randomized controlled trial is needed to address these issues and their relative importance.

Antineutrophil cytoplasm autoantibodies from patients with systemic vasculitis activate neutrophils through distinct signaling cascades: comparison with conventional Fcgamma receptor ligation

In systemic vasculitis, interactions between antineutrophil cytoplasm autoantibodies (ANCAs) and neutrophils initiate endothelial and vascular injury. ANCAs directed against either myeloperoxidase (MPO) or proteinase 3 (PR3) can activate cytokine-primed neutrophils by binding cell surface-expressed MPO or PR3, with the concurrent engagement of Fcgamma receptors (FcgammaR). Because roles for phospholipase D (PLD) and phosphatidylinositol 3 kinase (PI3K) have been demonstrated in FcgammaR activation of neutrophils, this study investigated the hypothesis that ANCA stimulation of neutrophils involved a similar engagement of FcgammaR and activation of PLD and PI3K. Pretreatment of tumor necrosis factor (TNF) alpha-primed neutrophils with antibodies against FcgammaRII and FcgammaRIII inhibited MPO-ANCA and PR3-ANCA induced superoxide generation, confirming that FcgammaR ligation is involved in ANCA-mediated neutrophil activation. However, although stimulation of TNF-alpha-primed neutrophils by conventional FcgammaR ligation, either using antibody-mediated cross-linking of FcgammaR or aggregated IgG, induced PLD activation, ANCA stimulation did not. Moreover, although ANCA-induced neutrophil activation results in significant PI3K activation-as assessed by phosphatidylinositol 3,4,5-triphosphate generation-conventional FcgammaR ligation, but not ANCA, activates the p85/p110 PI3K subtype. Inhibition of ANCA-induced superoxide generation with pertussis toxin suggests that ANCAs activate the p101/p110gamma PI3K isoform. In addition, the kinetics of activation of protein kinase B differs between conventional FcgammaR ligation and ANCA stimulation of neutrophils. These results demonstrate that though ligation of FcgammaRIIa and FcgammaRIIIb may be necessary, it is likely that ANCAs require other membrane cofactors for neutrophil activation.

Th2 dominance in nasal mucosa in patients with Wegener's granulomatosis

Wegener's granulomatosis initially affects upper respiratory tract organs including the nasal mucosa in more than 90% of patients. The inflammation is typically granulomatous with associated vasculitis. T lymphocytes are usually a prominent component of the leucocyte infiltrate. Previous studies using peripheral blood T cells have implicated IFN-gamma rich Th1-type responses. This study addressed the cytokine milieu in nasal mucosa from 10 patients with active Wegener's granulomatosis using immunohistochemistry. Increased levels of CD3+ T cells and eosinophils were present compared with normal and disease controls. There was increased expression of IL-4, down-regulation of IL-2 and no detectable IFN-gamma. There was increased expression of the chemokine receptor CCR3 by infiltrating cells, consistent with an IL-4 dominant, Th2-biased response. In contrast, renal biopsy tissue from 10 patients with active Wegener's granulomatosis showed expression of IL-2 and IL-4. The Th2-type environment within nasal mucosa, often the initial site of disease activity in Wegener's, is consistent with a local allergic response in these patients.

Potential role for monocyte chemotactic protein-4 (MCP-4) in monocyte/macrophage recruitment in acute renal inflammation

The CC chemokine, monocyte chemoattractant protein-4 (MCP-4), is an important chemoattractant for monocytes and T cells. Recent data indicate a role in renal inflammation. This study has used in situ hybridization and immunohistochemical analysis of cryostat sections of biopsy material taken from patients with acute renal allograft rejection and vasculitic glomerulonephritis to demonstrate renal expression of MCP-4, both at message and protein level. MCP-4 was primarily expressed at peritubular, periglomerular, and perivascular sites, irrespective of the inflammatory condition, and was associated with infiltrating CD3-positive lymphocytes and CD68-positive monocyte/macrophages. In addition, proximal tubular epithelial cells grown in culture from cortical fragments of human kidney showed low levels of constitutive MCP-4 expression, detectable by western blotting; this expression of MCP-4 was up-regulated in response to the pro-inflammatory cytokines, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). CCR3-, CCR5- and CCR2-expressing leukocyte populations were identified at sites of MCP-4 expression. Double-staining techniques revealed that CC chemokine receptor-expressing cells were primarily CD68-positive. These studies suggest an important role for MCP-4 in the recruitment and retention of monocytes/macrophages in renal inflammation.

Neutrophil priming and apoptosis in anti-neutrophil cytoplasmic autoantibody-associated vasculitis

BACKGROUND

Interactions between anti-neutrophil cytoplasmic autoantibody (ANCA) and primed neutrophils (PMNs) may be central to the pathogenesis of primary small vessel vasculitis. PMNs from patients are primed, expressing proteinase 3 (PR3) on the cell surface, which permits interaction with ANCA. In vitro ANCA activates primed PMN to degranulate and generate a respiratory burst. Resultant reactive oxygen species are important in triggering apoptosis, but the fate of PMN in ANCA-associated vasculitis is unknown. Failure to remove apoptotic PMN in a nonphlogistic manner may sustain the inflammatory response.

METHODS

PMNs from patients or controls were isolated, and the basal production of superoxide was measured by the superoxide dismutase-inhibitable reduction of ferricytochrome C. ANCA antigen expression on apoptotic PMN was assessed at 0, 12, and 18 hours by flow cytometry using dual staining with FITC-conjugated annexin V and PE-conjugated anti-murine IgG against monoclonal ANCA. Apoptosis was also assessed by morphology. In further studies, apoptotic PMNs were opsonized with monoclonal anti-myeloperoxidase (MPO) or anti-proteinase-3 (PR3) or irrelevant isotype-matched IgG (N IgG) and phagocytosis by macrophages was measured using interaction assays. Cytokines interleukin-8 (IL-8) and interleukin-1 were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Proteinase-3 expression (active 63.04 +/- 5.6% of total number of cells, remission 51.47 +/- 7.9% of total number of cells, control 17.7 +/- 4.7% of total number of cells, P < 0.05) and basal superoxide production (active 6.9 +/- 0.8 nmol/L x 10(6) cells, remission 5.15 +/- 0.4 nmol/L/10(6) cells, control 3.63 +/- 0.3 nmol/L/10(6) cells, P < 0.001) were significantly greater with freshly isolated PMN from patients than controls. PR3 expression and superoxide generation were positively correlated. PMN from patients with active disease became apoptotic at a greater rate than those of controls (at 18 hours, patients 72.3 +/- 3.9% apoptosis, controls 53.2 +/- 2.7% apoptosis, P < 0.05). PR3 and MPO expression were significantly greater on PMN isolated from patients at 12 and 18 hours. Opsonization of apoptotic PMN with ANCA significantly enhanced recognition and phagocytosis by scavenger macrophages (anti-MPO 88.95 +/- 6.27, anti-PR3 93.98 +/- 4.90, N IgG 44.89 +/- 3.44, P < 0.01) with increased secretion of IL-1 (anti-PR3 34.73 +/- 6.8 pg/mL, anti-MPO 42.01 +/- 12.3 pg/mL, N IgG 8.04 +/- 6.3 pg/mL, P < 0.05) and IL-8 (anti-PR3 8.97 +/- 0.93 ng/mL, anti-MPO 8.45 +/- 1.46 ng/mL, N IgG 0.96 +/- 0.15 ng/mL, P < 0.01).

CONCLUSION

In vivo circulating PMNs are primed as assessed by PR3 expression and basal superoxide production, thereby enhancing their inflammatory potential. These PMNs undergo apoptosis more readily, at which times they express PR3 and MPO on their surface. These antigens may then provide targets for ANCA. Opsonization of apoptotic PMN will enhance clearance by macrophages but will also trigger the release of pro-inflammatory cytokines that may contribute to chronic inflammation.

IgG from myeloperoxidase-antineutrophil cytoplasmic antibody-positive patients stimulates greater activation of primed neutrophils than IgG from proteinase 3-antineutrophil cytosplasmic antibody-positive patients

OBJECTIVE

Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA) have been reported to be pathologically and clinically different. The aim of this study was to assess whether these differences could be explained by differing abilities of proteinase 3-antineutrophil cytoplasmic antibody (PR3-ANCA)-positive IgG preparations or myeloperoxidase-ANCA (MPO-ANCA)-positive IgG preparations to activate neutrophils (polymorphonuclear cells [PMN]) in vitro.

METHODS

Using Percoll density gradients, PMN were isolated (concentration 2 x 10(6)/ml) and primed with cytochalasin B (1 ng/ml) and tumor necrosis factor alpha (TNFalpha; 2 ng/ml). The PMN were activated with 200 microg/ml of normal IgG or ANCA. Activation was determined by 1) superoxide anion generation as determined by the superoxide dismutase-inhibitable reduction of ferricytochrome c, 2) monitoring fluxes in Ca2+ concentration using Fura 2-AM-loaded PMN, and 3) degranulation using an MPO assay. Surface expression of PR3 and MPO was determined by fluorescence-activated cell sorter analysis. ANCA isotypes were investigated by enzyme-linked immunosorbent assay.

RESULTS

Activation of PMN by MPO-ANCA-positive IgG preparations compared with PR3-ANCA-positive IgG preparations resulted in greater generation of superoxide anions (MPO-ANCA-positive IgG preparations 9.13 +/- 0.39 nmoles [mean +/- SEM], PR3-ANCA-positive IgG preparations 6.32 +/- 0.35 nmoles; P < 0.001), Ca2+ fluxes (MPO-ANCA-positive IgG preparations 0.735 +/- 0.10, PR3-ANCA-positive IgG preparations 0.33 +/- 0.098; P < 0.01), and MPO degranulation (MPO-ANCA-positive IgG preparations 251.98 +/- 26.7 ng, PR3-ANCA-positive IgG preparations 145.19 +/- 19.4 ng; P < 0.001). The increased activation seen with MPO-ANCA-positive IgG preparations was not due to increased expression of MPO on the cell surface, because following TNFalpha priming PR3 was expressed on significantly more cells than was MPO (PR3 expression 54.2 +/- 5.18%, MPO 31.6 +/- 3.55%; P < 0.001). IgG1 and IgG4 were the predominant isotypes in both MPO-ANCA-positive IgG preparations and PR3-ANCA. MPO-ANCA contained significantly more IgG1 than did PR3-ANCA, and PR3-ANCA-positive IgG preparations contained significantly more IgG3.

CONCLUSION

In vitro MPO-ANCA-positive IgG preparations are more activating than PR3-ANCA-positive IgG preparations. The increased activation cannot be explained by increased MPO expression on the cell surface or greater IgG3 present in MPO-ANCA-positive IgG preparations. Differences in activation of PMN by these antibodies may determine some differences between WG and MPA.

Antineutrophil cytoplasm antibody-induced neutrophil nitric oxide production is nitric oxide synthase independent

BACKGROUND

Antineutrophil cytoplasm antibodies (ANCAs) are implicated in the pathogenesis of systemic vasculitis. We asked whether ANCA could induce nitric oxide (NO) release from human neutrophils and, if so, whether this NO production was dependent on NO synthase (NOS) activity.

METHODS

Neutrophil NO production was measured using a chemiluminescence assay, and NOS activity was determined by the conversion of [(14)C] L-arginine to [(14)C] L-citrulline and NOS mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Human neutrophils isolated from healthy donors were incubated at 37 degrees C with human ANCA, normal human IgG, murine monoclonal myeloperoxidase ANCA, murine proteinase-3 ANCA, or their respective isotypic controls for 6 to 12 hours in RPMI. Both human and monoclonal ANCA led to a dose-dependent increase of NO compared with control IgG. Neutrophils, either freshly isolated or incubated for seven hours with murine monoclonal myeloperoxidase ANCA, proteinase-3 ANCA, or a mixture of interleukin-1 beta, tumor necrosis factor-alpha, interferon-gamma plus lipopolysaccharide showed no NOS activity with low conversion rates of [(14)C] L-arginine to [(14)C] L-citrulline, which could not be inhibited by N(G)-monomethyl-L-arginine (NOS inhibitor). To detect NOS mRNA expression, RT-PCR was performed using oligonucleotide primers derived from mRNA sequences of either human constitutive endothelial NOS (eNOS), constitutive neuroneal NOS (nNOS), or human hepatocyte inducible NOS (iNOS). There was no expression of either eNOS, nNOS, or iNOS in untreated, human and murine monoclonal ANCA-treated, or cytokine-treated neutrophils.

CONCLUSION

These data suggest that human neutrophils produce NO in response to ANCA but in a NOS-independent way. NO can be generated from a nonenzymatic interaction between hydrogen peroxide and arginine. We postulate that this is the predominant pathway of NO synthesis in neutrophils, since ANCAs are capable of inducing reactive oxygen species production from neutrophils.

Unusual T cell receptor phenotype V gene usage of gamma delta T cells in a line derived from the peripheral nerve of a patient with Guillain-Barré syndrome

Guillain-Barré syndrome is considered to be an immune mediated disorder but the relative role of T cells and antibodies in its pathogenesis is unclear. As gut infection with Campylobacter jejuni is the most common antecedent infection it is possible that gut derived T lymphocytes might play a part in the development of the syndrome. The T cell receptor phenotype (TCR) of a nerve gamma delta T cell line obtained from a sural nerve biopsy taken from a patient with a demyelinating form of GBS was determined using polymerase chain reaction (PCR) and flow cytometry (FACS). This TCR was compared with the phenotype preferentially expressed in the peripheral blood of the same patient. The T cell nerve line was found to express V gamma 8/delta 1 which represents an unusual T cell subset normally found on lymphocytes resident in epithelial tissue such as the gut. The peripheral blood gamma delta T lymphocytes from the patient were of the V gamma 9/delta 2 subset, which is the phenotype predominantly expressed in the peripheral blood of healthy subjects. In conclusion, the presence of this unusual population of V gamma 8/delta 1(+) lymphocytes in nerve would be consistent with a pathogenetic role for gut associated lymphocytes in the pathogenesis of Guillain-Barré syndrome associated with C jejuni.