[Pharmacological and clinical profiles of avacopan (TAVNEOS® capsule), a selective C5a receptor antagonist]

Avacopan (TAVNEOS® capsules) is an orally available selective C5a receptor (C5aR) antagonist. It has been approved in Japan since 2021 for the treatment of microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA), the two major subtypes of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The current standard therapy combining glucocorticoids (GC) and immunosuppressants has greatly improved the prognosis of AAV, however, issues such as side effects associated with GC use remain to be resolved. Avacopan suppresses priming of neutrophils induced by the complement component C5a, a process deeply involved in the pathogenesis of AAV. In pre-clinical studies, avacopan inhibited chemotaxis and priming of neutrophils induced by C5a-C5aR signaling. It also significantly suppressed nephritis and renal damage in an ANCA-induced glomerulonephritis mouse model. In the global phase 3 study "ADVOCATE", avacopan achieved both primary endpoints being 1) non-inferior to prednisone in inducing remission at week 26 and 2) superior in sustained remission at week 52 for MPA and GPA patients. Additionally, with avacopan, GC toxicity score was significantly lower and fewer adverse events possibly related to GC were observed. Furthermore, avacopan increased estimated glomerular filtration rate (eGFR) more than prednisone indicating improved renal function. Thus, the novel mechanism of avacopan targeting the complement system is a promising new therapeutic option for AAV with fewer GC-related side effects and better improvement of renal function.

Kidney biopsy in patients with antineutrophil cytoplasmic antibody-associated vasculitis with mild renal abnormality

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a systemic inflammation of small or medium blood vessels that includes microscopic polyangiitis. A diagnosis of ANCA-associated vasculitis can be aided by histological identification of vasculitis, and identification of renal impairment can help predict outcomes. However, kidney biopsy is not generally indicated in the absence of renal findings. We report two cases of ANCA-associated vasculitis diagnosed by kidney biopsy despite the absence of remarkable urinary abnormality and renal impairment. These patients had fever of unknown origin and were positive for myeloperoxidase (MPO)-ANCA but showed few findings that would suggest small-vessel vasculitis in the kidney. Nevertheless, kidney biopsies revealed small-vessel arteritis, necrotizing glomerulonephritis, and interstitial nephritis. Immunofluorescent antibody tests performed using samples of glomeruli were all negative, suggesting microscopic polyangiitis. Therefore, kidney biopsy may be useful in confirming the diagnosis, even if patients have completely normal urinary findings in the absence of other organ lesions.

SARS-COV-2 INFECTION AS A POSSIBLE TRIGGER FOR MICROSCOPIC POLYANGIITIS: CASE REPORT AND MINI-REVIEW

The paper presents a clinical case of MPA in a 67-year-old woman following COVID-19, characterized by significant difficulties when working with the early etiological verification of diagnosis. The patient presented with polyarthritis affecting the upper and lower limbs, fever, and comorbid urological pathology in the form of urolithiasis and recurrent cystitis. This clinical presentation, hyperuricemia, azotaemia and anemia were mistakenly interpreted as chronic kidney disease: gouty nephropathy, gouty arthritis, which masked the underlying disease for a long time delaying the timely MPA diagnosis and treatment. Given that MPA is a multisystemic disease, it is essential to enhance awareness and knowledge of healthcare professionals of various specialties regarding AAVs and MPA in particular, as evidenced by the online survey data during COVID-19 pandemic among doctors in 21 countries.

Fibrosis-5 predicts end-stage renal disease in patients with microscopic polyangiitis and granulomatosis with polyangiitis without substantial liver diseases

We previously reported that fibrosis-4 (FIB-4) was associated with poor outcomes of microscopic polyangiitis (MPA) and granuloma with polyangiitis (GPA). We also investigated the potential of FIB-5, a novel index, in predicting all-cause mortality and end-stage renal disease (ESRD) during follow-up in patients with MPA and GPA without substantial liver diseases. Clinical and laboratory data at diagnosis were collected by reviewing the medical records of 180 patients with MPA and GPA. FIB-5 was obtained by a following equation: FIB-5 = (serum albumin (g/L) × 0.3 + platelet count (10⁹/L) × 0.05) − (alkaline phosphatase (IU/L) × 0.014 + aspartate aminotransferase/alanine aminotransferase ratio × 6 + 14). The median age of the patients at diagnosis was 61.0 years. FIB-5 at diagnosis could not reflect the cross-sectional vasculitis activity. The cutoffs of FIB-5 for poor outcomes was set as 0.82 (the lowest tertile) and -0.42 (the lowest quartile) at diagnosis. In Kaplan–Meier survival analysis, patients with FIB-5 < 0.82 and those with FIB-5 < -0.42 exhibited lower ESRD-free survival rates than those without. However, it could not predict all-cause mortality. In multivariable Cox hazards analysis, both FFS (Hazard ratio (HR) 1.554) and FIB-5 < 0.82 (HR 2.096) as well as both FFS (HR 1.534) and FIB-5 < -0.42 (HR 2.073) at diagnosis independently predicted ESRD during follow-up. In conclusion, FIB-5 < 0.82 and FIB-5 < -0.42 at diagnosis could predict the occurrence of ESRD, but not all-cause mortality, during follow-up in patients with MPA and GPA without substantial liver diseases.

Lung involvement in ANCA-associated vasculitis

Lung involvement is one of the most common clinical features in ANCA-associated vasculitides (AAV), including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). In this review, we detail the five main presentations of pulmonary involvement in AAV: necrotizing granulomatous inflammation, tracheobronchial inflammation, pulmonary capillaritis, interstitial lung disease (ILD) and asthma with their clinical, radiological and therapeutic characteristics. The prevalence of these manifestations is variable according to the subtype of AAV, necrotizing granulomatous inflammation and tracheobronchial inflammation being defining features of GPA whereas ILD is primarily seen in patients with MPA, especially in association with ANCA directed against myeloperoxydase (MPO-ANCA), and asthma is characteristic of EGPA. Despite recent progresses in the diagnosis and management of these conditions, several questions remain and are discussed here, including local treatments for subglottic stenosis, the uncertain efficacy of plasma exchanges for alveolar hemorrhage, the potential role of antifibrotic agents in ILD associated with MPA, and the use of novel anti-IL-5 strategies in EGPA.

Updates in the treatment of granulomatosis with polyangiitis and microscopic polyangiitis: At a crossroad

There have been great advances in the management of ANCA associated vasculitis over the past decades. We have gone from an era where the disease was almost universally fatal to trying to prevent long-term side effects of treatment regimens. With the ability to use pulse cyclophosphamide or rituximab as alternates to oral cyclophosphamide for induction of remission, side effects of therapy have been greatly reduced. New approaches have drastically changed our approach to maintenance and we now favor much longer durations of maintenance therapy, as they are more successful in preventing relapse. Steroids have long been the bane of treatment as they are associated with a significant risk of infection and metabolic consequences. We are now in a steroid-sparing and looking ahead to a steroid-free era with new data being published showing lower doses of steroids being equally effective and several ongoing seminal trials looking at agents that could completely replace steroids very early on.

How to improve the histopathological diagnosis of systemic vasculitides in daily practice?

The most common group of systemic vasculitides in adulthood are anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). AAV represent autoimmune systemic vasculitides and include 3 clinical phenotypes: Granulomatosis with polyangiitis (GPA, formerly Wegener granulomatosis), Microscopic polyangiitis (MPA) and Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome). Histological features are similar to each other in all affected locations, and there are represented by necrotizing vascular inflammation of small and medium calibers, often venules, capillaries or arteriols, typically with fibrinoid vessel wall necrosis. The consequences of this condition are bleeding, as well as compromise of the lumen which may result in downstream tissue ischemia and necrosis. Typically affected locations in biopsy practice are: ENT, lung, skin, GIT, and kidney. The aim of this review is to provide a comprehensive overview of the important histopathological findings. ANCA positive vasculitis is a serious life-threatening disease and therefore requires a rapid diagnosis and appropriate therapy.

Neutrophils from ANCA-associated vasculitis patients show an increased capacity to activate the complement system via the alternative pathway after ANCA stimulation

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV), including granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), are autoimmune conditions associated with small vessel inflammation. Earlier studies indicate that complement activation via the alternative pathway plays a major role in the pathogenesis. In this study we have investigated if ANCA-activation of neutrophils from AAV patients leads to activation of the alternative complement pathway. C5a-primed neutrophils (PMN) from 10 AAV patients and 10 healthy controls (HC) were stimulated with PMA or IgG purified from PR3-ANCA positive patients (ANCA IgG). The supernatants were analyzed for release of complement proteins and markers of different granules by ELISA, and release of microparticles (MP) by flow cytometry. The ability of the supernatants to activate the alternative complement pathway was determined by incubation with normal serum and C3bBbP and C5a were measured by ELISA. MP were analyzed by flow cytometry and removed by centrifugation. The supernatants from the AAV patients’ neutrophils produced significantly more C3bBbP compared with HCs (p = 0.0001). C3bBbP levels correlated with the number of MP. After removal of MP from the supernatants, alternative pathway activation was significantly lower. This study shows that primed and ANCA-stimulated neutrophils from AAV patients have a greater ability to activate the alternative complement pathway compared to primed neutrophils from healthy controls. This finding emphasizes the role of complement in the pathogenesis of AAV - underlining the therapeutic potential of C5a and other complement blockade.

Protective Role of HLA-DRB1*13:02 against Microscopic Polyangiitis and MPO-ANCA-Positive Vasculitides in a Japanese Population: A Case-Control Study

Among antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV), granulomatosis with polyangiitis (GPA) and proteinase 3-ANCA-positive AAV (PR3-AAV) are prevalent in European populations, while microscopic polyangiitis (MPA) and myeloperoxidase-ANCA-positive AAV (MPO-AAV) are predominant in the Japanese. We previously demonstrated association of DRB1*09:01-DQB1*03:03 haplotype, a haplotype common in East Asians but rare in the European populations, with MPA/MPO-AAV, suggesting that a population difference in HLA-class II plays a role in the epidemiology of this disease. To gain further insights, we increased the sample size and performed an extended association study of DRB1 and DPB1 with AAV subsets in 468 Japanese patients with AAV classified according to the European Medicines Agency algorithm (MPA: 285, GPA: 92, eosinophilic GPA [EGPA]: 56, unclassifiable: 35) and 596 healthy controls. Among these patients, 377 were positive for MPO-ANCA and 62 for PR3-ANCA. The significance level was set at α = 3.3x10-4 by applying Bonferroni correction. The association of DRB1*09:01 with MPO-AAV was confirmed (allele model, P = 2.1x10-4, odds ratio [OR] = 1.57). Protective association of DRB1*13:02 was detected against MPO-AAV (allele model, P = 2.3x10-5, OR = 0.42) and MPA (dominant model, P = 2.7x10-4, OR = 0.43). A trend toward increased frequency of DPB1*04:01, the risk allele for GPA in European populations, was observed among Japanese patients with PR3-AAV when conditioned on DRB1*13:02 (Padjusted = 0.0021, ORadjusted = 3.48). In contrast, the frequency of DPB1*04:01 was decreased among Japanese patients with MPO-AAV, and this effect lost significance when conditioned on DRB1*13:02 (Padjusted = 0.16), suggesting that DRB1*13:02 or other allele(s) in linkage disequilibrium may be responsible for the protection. The differential association of DPB1*04:01 with PR3-AAV and MPO-AAV and difference in DPB1*04:01 allele frequencies between populations supported the hypothesis that the HLA-class II population difference may account in part for these epidemiologic characteristics. Furthermore, taken together with our previous observations, the haplotype carrying DRB1*13:02 was suggested to be a shared protective factor against multiple autoimmune diseases.

Clinical features of children with pulmonary microscopic polyangiitis: report of 9 cases

Kidneys and lungs are the most common organs involved in microscopic polyangiitis (MPA). A retrospective analysis of pediatric MPA patients with pulmonary lesions over the past 10 years was performed to investigate clinical features of MPA in children with pulmonary lesions. There were 9 patients enrolled in our study, including 2 boys and 7 girls, with a median age of 6.6 years at the time of disease onset and a median disease course of 2 months. All of the patients exhibited tachypnea, and 7 exhibited cough and hemoptysis. The most common presentation on pulmonary imaging was ground glass or patchy shadows, which were observed in 6 cases. Seven patients manifested with hematuria and proteinuria, with renal histopathology of fibrinoid necrosis/exudation of the glomerular capillaries. All of the patients presented with normocytic normochromic anemia. Of the 9 patients, 7 were positive for perinuclear antineutrophil cytoplasmic antibody (p-ANCA) and/or myeloperoxidase (MPO), and 2 were positive for p-ANCA/MPO and cytoplasmic ANCA/proteinase 3. Eight patients had normal complement 3 (C3) levels, and one had an elevated C3 level. Five of the 9 patients were positive for antinuclear antibody ANA, and 4 were positive for double strand DNA (ds-DNA) antibody (3 were positive for both). The 7 patients who exhibited renal involvement received steroid plus cyclophosphamide (CTX) treatment. Of these patients, 4 achieved various degrees of remission, 2 were at the beginning of induction therapy, and one was lost to follow-up. Two patients with isolated pulmonary involvement received steroid plus leflunomide treatment and achieved complete remission. Diffuse alveolar hemorrhage was the most frequent presentation of lung involvement in children with MPA, and tachypnea, cough, hemoptysis and anemia were the common clinical symptoms. The majority of these patients exhibited hematuria, proteinuria and renal insufficiency. The efficacy of steroid plus CTX or leflunomide was evident in these patients.

[VASCULITIDES IN CHILDHOOD: A RETROSPECTIVE STUDY IN A PERIOD FROM 2002 TO 2012 AT THE DEPARTMENT OF PAEDIATRICS, UNIVERSITY HOSPITAL CENTRE ZAGREB]

The aim of our study was to analyze clinical features, laboratory findings, treatment, course and outcome of different types of vasculitis in children. All children aged up to 18 years that have been diagnosed with a vasculitis disorder from 2002. to 2012. at the Department of Paediatric, University Hospital Centre Zagreb according to EULAR/PRES/PRINTO criteria were included in the study. Vasculitis was diagnosed in 180 children, 101 girls and 79 boys, mean age 7.19 ± 3.7 years, with an average follow-up of 5.58 ± 3.28 years. Most of the children (155 or 86%) were diagnosed with Henoch-Shönlein purpura (HSP), polyarteritis nodosa (PAN) was diagnosed in 6 children (3.3%), isolated cutaneous leukocytoclastic vasculitis in 5 (2.8%), Takayasu arteritis (TA) and Kawasaki disease in 2 (1.1%) respectively, hypocomplementemic urticarial vasculitis in one patient (0.5%) and other types of vasculitis in 10 (5.5%) patients (vasculitides in systemic connective tissue disorders in 7 and unclassified vasculitides in 3 patients). All patients had elevated inflammatory markers (C-reactive protein and erythrocyte sedimentation rate). Anti-neutrophil cytoplasmatic antibodies (ANCA) were positive only in one patient, suffering from microscopic polyangiitis. Treatment modality in most patients were NSAIDs, while children with kidney or gastrointestinal system affection were treated with glucocorticoids and/or immunosuppresive drugs. Biological therapy (anti-CD20, rituximab) was used in patients with most severe symptoms. One child (0.56%), suffering from microscopic polyangiitis, died due to kidney failure during the follow-up. Forty patients (22.6%) had one disease relapse, while 6 (3.4%) had two relapses. In conclusion, we found some differences in laboratory parameters (e.g. lower incidence of elevated antistreptolysin O titer in HSP) and epidemiological data (e.g. higher prevalence of PAN in female children) in comparison to data from available studies, while other clinical features, laboratory findings, disease outcome and treatment were similar.

[THE MECHANISMS OF ACTION OF RITUXIMAB]

Rituximab is a chimeric monoclonal antibody containing constant kappa-regions of the Fc fragment of IgGI human immunoglobulin and variable fragments of IgG murine immunoglobulin. This modified immunoglobulin structure makes rituximab capable of specifically recognizing CD20 antigen that is mainly expressed on B-lymphocytes. The review considers four main mechanisms of rituximab action leading to reduction of the population of B-lymphocytes in patients with lymphoproliferative processes. All these mechanisms are probably operative under clinical conditions, however, their relative contributions to the clinical effect of rituximab can vary and are yet not defined in full.

[Clinical and pathological analysis of 25 cases of microscopic polyangiitis]

OBJECTIVE

To analyze the clinical and pathological features of microscopic polyangiitis (MPA) to improve the diagnosis and treatment of the disease.

METHODS

Twenty-five cases of MPA were retrospectively analyzed.

RESULTS

The onset symptoms of MPA, often nonspecific, included fever, muscle and joint pain, fatigue, loss of weight, etc, with varying degrees of proteinuria, hematuria and renal insufficiency. The pathological types revealed by renal biopsy were mainly focal segmental necrotizing glomerulonephritis or pauci-immune crescentic glomerulonephritis. Timely immunosuppressive therapy could improve the outcome.

CONCLUSION

The early symptoms of MPA are often nonspecific to easily result in misdiagnosis. Examination of ANCA titers and timely renal biopsy are helpful to establish an early diagnosis. Immune suppression therapy and plasma exchange when necessary should be initiated after the establishment of the diagnosis. The disease activity and drug toxicity should be carefully monitored to improve the prognosis.

[Clinical features of pulmonary involvement in patients with microscopic polyangiitis]

OBJECTIVE

To explore the clinical features of pulmonary involvement in patients with microscopic polyangiitis (MPA).

METHODS

We retrospectively investigated the clinical data of 50 patients hospitalized with MPA in Peking Union Medical College Hospital from January 2008 to December 2009, the data included clinical manifestation, laboratory parameters, echocardiography, pulmonary function test, chest computed tomography, and histopathology of kidney.

RESULTS

Pulmonary involvements were observed in 46 patients, common symptoms include cough (34/46), expectoration (30/46), dyspnea (19/46) and hemoptysis (16/46). Pulmonary involvement was the initial manifestation in 14 patients, five cases had radiographic evidences of usual interstitial pneumonia before MPA was diagnosed. The prevalence of positive MPO-ANCA antibodies in MPA patients was 96%. The prevalence of positive PR3-ANCA antibodies was 6%. Radiographic manifestations included ground glass attenuation (16/37), interstitial changes (16/37), infiltrates (12/37) and pleural effusion (7/37). The most frequent abnormality in pulmonary function test was reduced carbon monoxide diffusing capacity (12/15) and restrictive ventilation dysfunction (4/15). The incidences of pulmonary hypertension was 33% (13/39), the average pulmonary artery systolic pressure was (48 ± 8) mm Hg (1 mm Hg = 0.133 kPa).

CONCLUSION

The prevalence of pulmonary involvement in patients with MPA was high, pulmonary involvement was the initial manifestation in 28% patients. The clinical manifestations were nonspecific, radiographic manifestations included ground glass attenuation, interstitial changes, infiltrates and pleural effusion. The short term prognosis was well in patients with pulmonary involvement treated with systemic corticosteroids and cyclophosphamide, infection was a leading cause of death in patients with pulmonary involvement.

Nomenclature and classification of vasculitis: lessons learned from granulomatosis with polyangiitis (Wegener's granulomatosis)

Names influence how something is perceived. Diagnostic terms (diagnoses) are the names of diseases that are usually derived either from some distinctive characteristic of the disease or include an eponym recognizing someone who elucidated the disease. No matter how logical and appropriate a name may be, if it is not usable and used it is of no lasting value. This brief commentary focuses on the nomenclature of systemic vasculitides, and uses as a prime example Wegener's granulomatosis, which has been renamed recently 'granulomatosis with polyangiitis', in part because of concerns about the suitability of Friedrich Wegener as the source of an eponym. The most distinctive pathological feature of Wegener's granulomatosis is multi-focal necrotizing inflammation that has long been called granulomatosis. The systemic variant of Wegener's granulomatosis also is characterized by inflammation in many different vessels or different types, i.e. polyangiitis. Thus, granulomatosis with polyangiitis is a very appropriate alternative term for Wegener's granulomatosis. This term also is in accord with the name for a closely related vasculitis, i.e. microscopic polyangiitis. Terms that indicate aetiology and pathogenesis, when known, are useful to include in names for diseases (diagnoses). Anti-neutrophil cytoplasmic autoantibodies specific for myeloperoxidase (MPO-ANCA) or proteinase 3 (PR3-ANCA) are implicated in the cause of granulomatosis with polyangiitis and thus also should be specified in the diagnosis (e.g. PR3-ANCA-positive granulomatosis with polyangiitis or MPO-ANCA-positive microscopic polyangiitis). As our understanding of the clinical manifestations, pathogenesis and aetiology of vasculitides change over time, the names and approaches for diagnosing these diseases will change accordingly.

Microscopic polyangiitis presenting with medullary infarct

Microscopic polyangiitis is a small vessel vasculitis which is rarely associated with ischemic stroke. Cerebrovascular disease has rarely been reported in connection with this disease. It may cause fatal hemorrhage, hemorrhagic conversion and multiple lacunar infarcts. We report here a 55-year-old woman with left medullary oblangata infarction without any symptoms of microscopic polyangiitis. During hospitalization, retinal ischemia, mononeuritis multiplex and pulmonary infiltration developed. Sural nerve biopsy was concomitant with small vessel vasculitis. Elevated CRP and sedimentation and positive P-ANCA led to confirmation of a diagnosis of microscopic polyangiitis. Our patient is a rare case of microscopic polyangiitis presenting with medullary infarction. Although the characteristics of this disease are well-known, the first symptom can be a medullary infarction, which has not been reported in literature before.

Temporal artery involvement in microscopic polyangitis

An 81-year-old man was hospitalized because of fever and pain in the temporal region. Temporal artery biopsy revealed temporal arteritis; steroid therapy was started. Chest computed tomography and kidney biopsy revealed interstitial pneumonia and necrotizing crescentic glomerulonephritis, respectively. Because his myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) level was 215.0 U/mL, a diagnosis of microscopic polyangitis (MPA) was made. The patient was discharged after reduction of the steroid dose. However, his respiratory symptoms exacerbated, necessitating rehospitalization. He died 1 week later due to respiratory failure. MPA rarely involves the temporal artery. In the cases of large vessel lesions, ruling out MPA is important.

[Case of microscopic polyangiitis accompanied by central nervous system symptoms and brain vasculitis observed histopathologically]

A 65-year-old-man complained of coughing and fever. The urine showed microscopic hematuria. The level of myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) was 167 EU. Two months later, he was admitted to our hospital with pulmonary hemorrhage and progressive renal dysfunction. He was treated with intravenous methylprednisolone followed by oral prednisolone with plasma exchanges, and his first pulmonary hemorrhage was relieved. Three weeks later, he suffered from a second diffuse pulmonary hemorrhage with central nervous system symptoms. He was treated again with intravenous methylprednisolone, plasma exchanges, and also intravenous pulse cyclophosphamide (IVCY), but he died of respiratory failure. Autopsy findings revealed microscopic polyangiitis (MPA)in the brain as well as in the lung, kidney and gastrointestinal system. The histopathological findings suggested that cerebral nervous system symptoms could have been caused by brain vasculitis in this case.

[An autopsy case of microscopic polyangiitis associated with bacterial endocarditis]

The patient was an 87-year-old man whose initial symptom was general fatigue and inappetence. His laboratory data revealed a rise in C-reactive protein (CRP) and white blood cell count (WBC), and CT scan showed suspicious pneumonia. Antibiotics were given to the patient, but his fever and laboratory data were sustained. Follow up examination revealed a high titer (107 U/ml) of myeloperoxidase specific anti-neutrophil cytoplasmic autoantibody (MPO-ANCA). He was diagnosed with MPO-ANCA associated vasculitis. Steroid pulse therapy was started. The patient's clinical symptoms and laboratory data thereafter significantly improved, but after one week the patient's symptom was aggravated and he died. An autopsy was performed, and necrotizing arteritis of the interlobular arteries were found in the kidneys. We found bacterial infective vegetation attached to the aortic valve. Infected thromboembolus and microabscesses were also found in many organs. We report a case of subacute microscopic polyangiitis associated with bacterial endocarditis.

New advances in the pathogenesis of ANCA-associated vasculitides

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a group of autoimmune disorders including Wegener's granulomatosis (WG), microscopic polyangiitis (MPA), Churg-Strauss syndrome (CSS) and renal-limited vasculitis (RLV). This paper reviews updated information on the pathogenesis of AAV. Additional clinical evidence for a pathogenic role of ANCA comes from the observation that patients with severe acute renal failure treated with plasma exchange had a lower risk for progression to end-stage renal disease than patients who received intravenous methylprednisolone therapy, both in addition to standard treatment. Recent data also suggest that antibodies to complementary proteinase-3 (cPR3), probably cross-reacting with plasminogen, may induce PR3-ANCA. Furthermore, a new ANCA, directed against human lysosome membrane protein-2 (LAMP-2), concurrent with PR3-ANCA or MPO-ANCA, was described as a sensitive and specific marker for renal AAV. In vitro, ANCA can further activate primed neutrophils to release reactive oxygen species and lytic enzymes, and, in conjunction with neutrophils, damage and lyse endothelial cells. In vivo, transfer of splenocytes from myeloperoxidase-deficient mice immunized with mouse myeloperoxidase into wild-type mice resulted in pauci-immune systemic vasculitis. A similar experiment in PR3-deficient mice did not cause significant vasculitic lesions. In the anti-MPO induced vasculitis mouse model, a critical role of complement activation was suggested. The anti- LAMP-2 antibody can also induce pauci-immune necrotizing crescentic glomerulonephritis in rats. Rats developed both cross-reactive antibodies to LAMP-2 and crescentic glomerulonephritis when immunized with FimH, an adhesin from Gram-negative bacteria which has strong homology with human LAMP-2. Together, clinical, in vitro and in vivo data support a pathogenic role for ANCA in AAV, although this role is more evident for myeloperoxidase-ANCA than for PR3-ANCA. The role of anti- LAMP-2 requires further studies.

Expression of CD57 on CD8+ T lymphocytes of patients with Wegener's granulomatosis and microscopic polyangiitis: evidence for continuous activation of CD8+ cells

OBJECTIVES

To gain insight into the immune pathogenesis of Wegener's granulomatosis (WG) and microscopic polyangiitis (MPA), the prevalence of circulating CD8+ T lymphocytes expressing CD57 as a marker for previous activation was analyzed.

METHODS

Receptor expression of CD57 was measured in CD8+ T cells of patients with active disease (n=5) by cytofluorometry and compared with expression in patients in remission (n=80) and in age-matched healthy donors (n=34). The results were compared to clinical parameters including severity and duration of the disease.

RESULTS

CD8+CD57+ were detected in patients with WG and MPA and in healthy donors as well and increased considerably with age. Compared to age-matched healthy donors, the prevalence of CD8+CD57+ was increased in the younger patients (up to 40 y). In most patients a high percentage of CD8+CD57+ coincided with severe disease and multiple organ involvement, while low CD8+CD57+ percentage was seen in patients with limited disease or in patients in complete remission. In patients with smoldering disease, the percentage of CD8+CD57+ increased with time. High numbers of CD8+CD57+ correlated with low CD4:CD8 ratio.

CONCLUSIONS

In patients with WG and MPA a population of CD8+CD57+ expand, identifying terminally differentiated CD8+ cells. The prevalence of CD57+ cells was related to the course of disease. So far, the function of CD57 on CD8+ cells is not understood. However, these cells might produce certain cytokines, which play a role in the pathogenesis of AAV. The data support the hypothesis that CD8+ T cells are activated in the context of primary vasculitides.

Clinical analysis of nervous system involvement in ANCA-associated systemic vasculitides

OBJECTIVE

To assess the clinical features of nervous system (NS) involvement in patients with ANCA-associated vasculitides (AAV), including microscopic polyangiitis (MPA), Wegener's granulomatosis (WG), and Churg-Strauss syndrome (CSS).

METHODS

One hundred and seventy-nine patients admitted to Peking Union Medical College Hospital from 1995 to 2008, including 93 cases of MPA, 61 cases of WG, and 25 cases of CSS, were enrolled in this study. Medical charts including demographic data, clinical features, laboratory findings, treatments and outcomes were systematically reviewed.

RESULTS

NS involvements were observed in 36.6% of MPA, 50.8% of WG, and 76.0% of CSS patients. Peripheral neuropathy predominated in each type of AAV. In CSS and MPA, the majority was mononeuritis multiplex and distal symmetrical polyneuropathy, whereas, differently, 64.5% of WG patients with NS involvement had cranial neuropathy. Central nervous system (CNS) involvement accounted for 21.1%, 29.4%, and 32.3% of neuropathy respectively in CSS, MPA and WG patients, including arachnoid hemorrhage, cerebrovascular neuro-pathy, meningitis, and diffuse brain damage. 157 (87.7%) AAV patients responded to treatment with high dose of prednisone plus immunosuppressants. Thirteen (14.0%) MPA and four (6.6%) WG patients died. The leading causes of death were diffuse alveolar hemorrhage (DAH) (6, 35.3%) and infection (6, 35.3%). No patient died directly of neuropathy.

CONCLUSION

NS involvement was common in AAVs and the characteristic of NS involvement was different among MPA, WG and CSS patients. DAH and infection instead of NS damage remained the leading causes of death in AAVs.