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.

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.

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.

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.

Treatment of vasculitic IgA nephropathy

BACKGROUND

Patients with IgA nephropathy and histological vasculitic/crescentic lesions have a poor prognosis. We performed a retrospective study to assess whether treatment with steroids and immunosuppressants would preserve renal function by healing these lesions and thereby prevent progression to glomerular sclerosis and renal failure.

METHODS

Sixteen patients with IgA nephropathy and a vasculitic/crescentic glomerulonephritis diagnosed by renal histology were treated with a reducing course of prednisolone (initial dose 60 mg/day). Six patients also received cyclophosphamide (2 mg/kg/day) for three months followed by azathioprine (100 mg/day) in five patients. Ten patients received azathioprine (100 mg/day) in addition to prednisolone. The median duration of treatment was 12 months (range 5-30 months). At the end of treatment each patient had a second renal biopsy.

RESULTS

Following treatment there was a significant reduction in the proportion of glomeruli with acute vasculitic lesions from a median of 17.4% (range 4.8-57.5%) to 0 (range 0-15.8%) (p=0.001). There was an increase in the proportion of globally sclerosed glomeruli from a median of 13.4% (range 0-44.4%) to 21.5% (range 0-90%) after treatment but this did not significantly differ from baseline (p=0.24). The proportion of renal cortex with chronic tubular atrophy increased from 2.55% (0.4-57.7%) to 11.3% (0.3-61%) (p=0.09). The median duration of follow-up was 30 months (inter-quartile range 6-30 months). At both 12 and 24 months there was no significant increase in serum creatinine. Four patients, however, developed end-stage renal failure between 24 and 81 months.

CONCLUSION

In this retrospective study we show that treatment with steroids and immunosuppressants leads to healing of vasculitic lesions and may thus arrest progression of glomerular scarring.

Antineutrophil cytoplasmic antibodies induce reactive oxygen-dependent dysregulation of primed neutrophil apoptosis and clearance by macrophages

This study assessed whether anti-neutrophil cytoplasmic antibodies (ANCAs) interfere with the safe deletion of neutrophils by apoptosis and phagocytic clearance. Tumor necrosis factor (TNF)-primed neutrophils were incubated with normal IgG (N IgG) or ANCA IgG for up to 36 hours. Compared with N IgG, ANCAs accelerated constitutive apoptosis of TNF-alpha primed neutrophils, as assessed by morphology and confirmed by DNA laddering pattern on gel electrophoresis, and accelerated progression to secondary necrosis. The accelerated apoptosis induced by ANCA was dependent on reactive oxygen species generation, as primed neutrophils from patients with chronic granulomatous disease failed to show an effect of ANCAs on apoptosis. However, there was no change in the rate at which neutrophils exhibited annexin V binding, indicating that externalization of phosphatidylserine was not accelerated by ANCAs. Furthermore, when ANCA-treated primed neutrophils were interacted with human or murine peritoneal macrophages after 12 hours there was significantly less phagocytosis by human macrophages and no difference in phagocytosis by murine peritoneal-derived macrophages when compared with N IgG-treated controls. In conclusion, ANCAs accelerate apoptosis and secondary necrosis in TNF-primed neutrophils by a mechanism dependent on the generation of reactive oxygen species, with uncoupling of nuclear and surface membrane changes, resulting in a "reduced window of opportunity" for phagocytic recognition and engulfment before disintegration.

Treatment of rolling neutrophils with antineutrophil cytoplasmic antibodies causes conversion to firm integrin-mediated adhesion

OBJECTIVE

The vascular lesions associated with autoimmune small-vessel vasculitis may arise from activation of circulating neutrophils by antineutrophil cytoplasmic antibodies (ANCA), resulting in increased adhesion of these neutrophils to the vessel wall. The present study examined the effects of ANCA-positive IgG (ANCA IgG), derived from patients with small-vessel vasculitis, on neutrophil adhesion.

METHODS

An in vitro, flow-based adhesion assay was used to determine the effects of ANCA IgG on neutrophils rolling on P-selectin presented by a monolayer of activated platelets. The platelets act as a surrogate vessel wall and can also support beta2 integrin-mediated immobilization of neutrophils if they are purposefully activated (e.g., by FMLP).

RESULTS

In the absence of any added agents, neutrophils rolled continuously over the platelet monolayer. Superfusion of ANCA IgG over rolling cells resulted in conversion to stationary adhesion accompanied by shape change. The ANCA-mediated response was transient, peaking at 5-6 minutes and returning to baseline by 15 minutes, even in the continued presence of ANCA. In contrast, normal (ANCA-negative) IgG and ANCA F(ab')2 fragments caused minimal conversion to stationary adhesion. Pretreatment of neutrophils with blocking antibodies directed toward Fc gamma receptor type IIA or the integrin chain CD11b completely inhibited the ANCA-mediated conversion, confirming that ANCA-mediated activation occurred through Fc gamma receptors and that neutrophil immobilization was mediated by the activated beta2 integrin (CD11b/CD18).

CONCLUSION

These findings support the concept that ANCA can directly activate neutrophils to become firmly adherent to vessel walls, where they may obstruct flow, initiate tissue damage, and contribute to pathogenesis of vasculitis.

Neutrophil FcgammaRIIIb allelic polymorphism in anti-neutrophil cytoplasmic antibody (ANCA)-positive systemic vasculitis

Neutrophils constitutively express FcgammaRIIa and FcgammaRIIIb receptors. Both receptors exhibit allelic variants which have different quantitative functional capacities: the biallelic FcgammaRIIa-R131 and -H131 alleles, and the neutrophil antigen (NA) NA1/NA2 alleles. ANCA activation of neutrophils requires ligation of FcgammaRIIa receptor, but recent data have shown that ANCA can also bind FcgammaRIIIb receptor. The aim of this study was to determine whether the FcgammaRIIIb polymorphism was a risk factor for the development of ANCA-associated systemic vasculitis, or the associated nephritis. FcgammaRIIIb receptor genotyping was determined by allele-specific polymerase chain reaction. Genomic DNA was extracted from 101 Caucasian patients with ANCA+ vasculitis (of whom 84 had renal disease) and 100 ethnically matched controls. Of the patients with ANCA+ systemic vasculitis, 71 had ANCA with specificity for proteinase 3 and 30 with specificity for myeloperoxidase (MPO). Overall no significant difference in genotype distribution or allele frequencies was found between patients and controls, or between patients with renal disease and controls. However, there was a trend for an increase in homozygosity for the NA1 allele in patients with a vasculitis and this was significant in patients who had anti-MPO antibodies. The FcgammaRIIIb receptor polymorphism is not a major factor predisposing to the development of ANCA+ systemic vasculitis or the associated nephritis. The over-representation of the FcgammaRIIIb homozygous NA1 allele in patients with anti-MPO antibodies may have implications for disease susceptibility.

Pathogenesis of ANCA-associated systemic vasculitis

The aetiology of primary systemic vasculitides remains unknown. Recent advances have been made in the understanding of relevant mechanisms of inflammation, particularly the role of the endothelium and interactions with inflammatory mediators and immune effector cells. In Wegener's granulomatosis and microscopic polyangiitis the evidence suggests an autoimmune inflammatory process, characterized by an early lesion involving neutrophils and endothelial cells as both targets and active participants; priming of neutrophils and endothelial cells allows ANCA to activate neutrophils with damage localized to the endothelium. In the absence of immune complex deposition, the role of the ANCA is particularly intriguing. Endothelial cell damage and activation produces pro-inflammatory mediators with influx monocytes and T cells intensifying damage. Increased understanding of the pathogenesis of systemic vasculitis is likely to provide the basis for the use of more selective immunomodulatory therapies in the future.

Is Wegener's granulomatosis an autoimmune disease?

Wegener's granulomatosis is a multisystem disease characterized by granulomata of the respiratory tract and systemic necrotising vasculitis. There is a strong and specific association with autoantibodies directed against proteinase 3, a constituent of neutrophril azurophilic granules. Antibody titers correlate with clinical disease activity and predict relapses. The disease responds favorably to immunosuppressive therapy. The pathogenicity of antineutrophil cytoplasmic antibodies (ANCA), however, remains unproven. In vitro, the expression of proteinase-3 and other ANCA antigens on the surface of neutrophils and monocytes can be induced by priming with proinflammatory cytokines. Antineutrophil cytoplasmic antibodies are then able to activate these leukocytes, stimulating degranulation, the production of reactive oxygen species, and the secretion of further cytokines. Neutrophils activated by ANCA, and possibly ANCA alone, directly damage endothelial cells in vitro. An animal model of proteinase 3-ANCA-induced vasculitis has not been found. Antineutrophil cytoplasmic antibodies directed against another antigen, myeloperoxidase, are not sufficient to cause vasculitis but they promote damage in certain animal models. Thus, a considerable amount of evidence supports the notion that Wegener's granulomatosis is an autoimmune disease.

Mechanisms of endothelial injury in systemic vasculitis

The precise etiology of primary systemic vasculitis remains unknown. However, recent advances in the understanding of the role of and interaction between the vascular endothelium, mediators, and immune effector cells have helped to further elucidate those specific processes that result in endothelial cell damage. In WG and MPA, the evidence favors an autoimmune inflammatory response characterized by specific mediators in which the endothelium is both target and active participant.

The activation of the neutrophil respiratory burst by anti-neutrophil cytoplasm autoantibody (ANCA) from patients with systemic vasculitis requires tyrosine kinases and protein kinase C activation

The ability of antineutrophil cytoplasm autoantibodies (ANCA) from patients with systemic vasculitis to stimulate protein kinase C (PKC) and tyrosine kinases was examined in human neutrophils. Using the superoxide dismutase-inhibitable reduction of ferricytochrome C, the kinetics of ANCA-induced superoxide (O2-) production were characterized and subsequently manipulated by specific inhibitors of PKC and tyrosine kinases. With this approach, ANCA IgG, but not normal IgG or ANCA F(ab')2 fragments caused a time and dose dependent release of O2- from TNF-alpha primed neutrophils. The kinetics of ANCA-induced O2- production showed an initial 10-15 min lag phase compared to the N-formyl-L-methionyl-L-leucyl-L-phenylalanine response, suggesting differences in the signalling pathways recruited by these two stimuli. Inhibitor studies revealed that ANCA-activation involved members of both the Ca2+-dependent and -independent PKC isoforms and also tyrosine kinases. ANCA IgG resulted in the translocation of the betaII isoform of PKC at a time corresponding to the end of the lag phase of O2- production, suggesting that PKC activity may be instrumental in processes regulating the activity of the NADPH oxidase in response to ANCA. Tyrosine phosphorylation of numerous proteins also peaked 10-15 min after stimulation with ANCA but not normal IgG. These data suggest that PKC and tyrosine kinases regulate O2- production from neutrophils stimulated with autoantibodies from patients with systemic vasculitis.

No association between neutrophil FcgammaRIIa allelic polymorphism and anti-neutrophil cytoplasmic antibody (ANCA)-positive systemic vasculitis

ANCA, implicated as having a pathogenic role in systemic vasculitis, can activate tumour necrosis factor-alpha (TNF-alpha)-primed neutrophils by cross-linking surface-expressed ANCA antigens with neutrophil FcgammaRIIa receptors to release reactive oxygen species. The FcgammaRIIa receptor exists as polymorphic variants, R131 and H131, which differ in their ability to ligate human IgG2 and IgG3. Neutrophils homozygous for the FcgammaRIIa-H131 allotype bind more efficiently to IgG3 than the FcgammaRIIa-R131 allotype and are the only human FcgammaR which bind IgG2. Our aim was to determine whether the homozygous FcgammaRIIa-H131 individuals are more susceptible to developing ANCA-associated systemic vasculitis and nephritis due to differential IgG binding and activation. FcgammaRIIa allotype was determined by both allele-specific polymerase chain reaction (PCR) and Southern blotting with allele-specific oligonucleotide probes end-labelled with 32P-gammaATP, after PCR amplification of genomic FcgammaRIIa DNA in 107 Caucasian patients with ANCA+ vasculitis (of whom 89 had renal disease) and 100 ethnically matched controls. Phenotyping of neutrophil FcgammaRIIa alleles was confirmed in some patients by quantitative flow cytometry using murine MoAbs 41H16 and IV.3. Of the patients with ANCA+ systemic vasculitis, 75 had ANCA with specificity for proteinase 3 and 32 with specificity for myeloperoxidase. Overall, no skewing in FcgammaRIIa allotypes was seen in patients compared with controls. No significant increase of the FcgammaRIIa-H131 allotype was found amongst patients irrespective of ANCA specificity, and no association between the FcgammaRIIa allotype and nephritis was found. Our data suggest that the FcgammaRIIa receptor allotype is not a major factor predisposing to the development of ANCA+ systemic vasculitis, or to nephritis.

International Consensus Statement on Testing and Reporting of Antineutrophil Cytoplasmic Antibodies (ANCA)

Antineutrophil cytoplasmic antibody (ANCA) tests are used to diagnose and monitor inflammatory activity in the primary systemic small vessel vasculitides. ANCA is best demonstrated in these diseases by using a combination of indirect immunofluorescence (IIF) of normal peripheral blood neutrophils and enzyme-linked immunosorbent assays (ELISAs) that detect ANCA specific for proteinase 3 (PR3) or myeloperoxidase (MPO). For ANCA testing in "new" patients, IIF must be performed on all serum samples. Serum samples containing ANCA, any other cytoplasmic fluorescence, or an antinuclear antibody (ANA) that results in homogeneous or peripheral nuclear fluorescence then should be tested in ELISAs for PR3-ANCA and MPO-ANCA. Optimally, ELISAs for PR3-ANCA and MPO-ANCA should be performed on all serum samples. Inclusion of the most recent positive sample in the IIF or ELISA may help demonstrate a change in antibody level. Reports should use recommended terms. Any report of positive neutrophil fluorescence issued before the ELISA results are available should indicate that positive fluorescence alone is not specific for the diagnosis of Wegener granulomatosis or microscopic polyangiitis and that decisions about treatment should not be based solely on the ANCA results.

IgG anti-endothelial cell autoantibodies from patients with systemic lupus erythematosus or systemic vasculitis stimulate the release of two endothelial cell-derived mediators, which enhance adhesion molecule expression and leukocyte adhesion in an autocrine manner

OBJECTIVE

To investigate the ability of anti-endothelial cell antibodies (AECA) to modulate endothelial cell function.

METHODS

The effects of purified IgG from 11 patients with systemic lupus erythematosus (SLE) and 4 patients with systemic vasculitis on the expression of adhesion molecules (intercellular adhesion molecule 1, vascular cell adhesion molecule 1, E-selectin) by human umbilical vein endothelial cells and on the adhesion of the human promyelocytic cell line U937 were examined in vitro.

RESULTS

IgG from 6 of 8 AECA-positive SLE patients and 3 of 3 AECA-positive systemic vasculitis patients up-regulated adhesion molecule expression and leukocyte adhesion to endothelial cells. The 4 AECA-negative samples had no effect. Transfer experiments demonstrated that at later time points (2-8 hours) after AECA addition, endothelium-derived interleukin-1 (IL-1) accounted for the ability of AECA to increase leukocyte adhesion. However, even within very short times after addition of AECA (<30 minutes), endothelial cells released a distinct transferable mediator with similar effects.

CONCLUSION

AECA in patients with SLE or systemic vasculitis may contribute to pathogenesis by increasing leukocyte adhesion to endothelial cells. AECA act by inducing the release of at least two endothelium-derived mediators, one (as-yet-unidentified) rapidly and another (IL-1) more slowly, both of which stimulate endothelial cells in an autocrine manner.

Interleukin-8: A pathogenetic role in antineutrophil cytoplasmic autoantibody-associated glomerulonephritis

BACKGROUND

In neutrophil trafficking, the role of interleukin-8 (IL-8) is location dependent. Tissue IL-8 directs transmigration, whereas intravascular IL-8 frustrates this process. The bystander damage of glomerular endothelium by antineutrophil cytoplasmic autoantibody (ANCA)-activated neutrophils is believed to be an early event in the pathogenesis of ANCA-associated glomerulonephritis. We have studied the role of IL-8 in this process.

METHODS

Intraglomerular expression of IL-8 in patients with ANCA-associated glomerulonephritis was studied by in situ hybridization and immunohistochemistry and location of neutrophils by serial section immunohistochemistry. In vitro, we analyzed ANCA-stimulated neutrophil IL-8 production by enzyme-linked immunosorbent assay, and the IL-8 attributable effect of ANCA-stimulated neutrophil supernatant by chemotactic and transendothelial assays.

RESULTS

There was intraglomerular expression of IL-8 at segmental, crescentic, and parietal epithelial sites. IL-8 protein expression colocalized to intraglomerular neutrophils; many localized within glomerular capillary loops, suggesting failed trafficking to tissue IL-8. ANCAs differentially stimulated time- and dose-dependent neutrophil IL-8 production, and ANCA-stimulated neutrophil supernatant demonstrated potent IL-8-dependent chemotactic activity and inhibited transendothelial migration of normal human neutrophils toward an IL-8 gradient.

CONCLUSION

Despite heavy tissue expression of IL-8 in ANCA-associated GN, the production of IL-8 by ANCA-stimulated neutrophils within the intravascular compartment may frustrate neutrophil transmigration, encourage intravascular stasis, and contribute to bystander damage of glomerular endothelial cells.

T lymphocyte adhesion mechanisms within inflamed human kidney: studies with a Stamper-Woodruff assay

Renal inflammatory conditions are characterized by mononuclear cell recruitment to sites of inflammation. We have developed a modified Stamper-Woodruff assay system to analyze mechanisms of functional T cell adhesion to cryostat sections of renal biopsy material from patients with vasculitic glomerulonephritis (GN) and acute allograft rejection. Peripheral blood T cells adhered to intraglomerular, periglomerular, and tubulointerstitial regions of the cortex. Blocking monoclonal antibodies against tissue expressed ICAM-1, VCAM-1, and the CS-1 domain of fibronectin (CS-1Fn) differentially attenuated T cell adhesion. Glomerular adhesion in vasculitic GN and tubulointerstitial adhesion in acute rejection were particularly sensitive to both anti-ICAM-1 and anti-VCAM-1 antibodies, indicating a prominent role for ICAM-1 and VCAM-1 at glomerular sites in vasculitis and at tubulointerstitial sites in rejection. Furthermore, using KL/4 cells (LFA-1 expressing) and Jurkat cells (VLA-4 expressing), we demonstrated specific LFA-1/ICAM-1- and VLA-4/VCAM-1-mediated interactions within glomerular and tubulointerstitial compartments. Jurkat cells also adhered to VCAM-1-free sites, and binding was inhibitable by anti-CS-1Fn antibody, thereby demonstrating a role for VLA-4/fibronectin interactions especially at intraglomerular sites in acute rejection where VCAM-1 is notably absent. We therefore propose a prominent functional role for ICAM-1, VCAM-1, and CS-1 domain fibronectin in T cell recruitment to the inflamed kidney.

In situ analysis of C-C chemokine mRNA in human glomerulonephritis

BACKGROUND

Glomerular and tubulointerstitial accumulations of macrophages and T cells are a prominent feature of immune inflammatory glomerulonephritis. The C-C family of chemokines are major mononuclear-cell chemoattractants and may be central to the recruitment of these cells.

METHODS

Using in situ hybridization (ISH) we analyzed the expression of mRNA for the C-C chemokines monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1alpha and beta (MIP-1alpha, MIP-1beta) and RANTES in renal biopsy material from twenty patients with glomerulonephritis.

RESULTS

In overt inflammatory glomerulonephritides, chemokine transcripts were differentially expressed by glomerular and tubulointerstitial leukocyte infiltrates, glomerular parietal and proximal tubular epithelial cells and endothelial cells. There was little expression in minimal change nephropathy and normal tissue. Expression of individual chemokines correlated with intrarenal T cell and macrophage infiltrates. Combined immunohistochemistry and ISH demonstrated that 56.9% of cells expressing MCP-1 mRNA were CD68+ve (monocytes/macrophages) and 53% of infiltrating CD68 +ve cells were MCP-1 mRNA positive.

CONCLUSIONS

These studies indicate that the in situ production of C-C chemokines by resident and infiltrating cells may play a crucial role in regulating macrophage and T-cell recruitment in glomerulonephritis.

T lymphocyte responses to anti-neutrophil cytoplasmic autoantibody (ANCA) antigens are present in patients with ANCA-associated systemic vasculitis and persist during disease remission

ANCA with specificity for myeloperoxidase (MPO) and proteinase 3 (PR3) are present in patients with systemic vasculitis. The aim of this work was to determine whether such patients have T cell responses to these antigens and whether these responses are related to disease activity. Peripheral blood lymphocytes from 45 patients and 19 controls were cultured with ANCA antigens and proliferation measured. The antigens used were heat-inactivated (HI) MPO, HI PR3, native (non-HI) PR3, HI whole alpha-granules, and 25 overlapping peptides covering the entire PR3 sequence. Significant responses to both whole PR3 preparations were seen from patient and control groups, and to the alpha-granules from the patient group. Patients responded at all stages of disease: active, remitting, treated or untreated. Only two patients responded significantly to MPO. Responses were significantly higher with the patient group than the control group to all four whole ANCA antigens. Responses to those PR3 peptides containing epitopes known to be recognized by ANCA were detected from one patient. Thus, these studies demonstrate that T cells from vasculitis patients can proliferate to PR3 and occasionally to associated ANCA antigens. Further, responses may persist even after disease remission has been achieved.