Long-term outcomes of childhood-onset systemic lupus erythematosus.

OBJECTIVE: Data on the long-term outcome of patients with childhood-onset Systemic Lupus Erythematosus (cSLE) are scarce. Aims of this study were to describe the long-term outcomes of cSLE and to identify factors associated with the development of damage and persistent disease activity. METHODS: We conducted a retrospective multicentre study using data from the PEDIALUP registry of the Juvenile Inflammatory Rheumatism (JIR) cohort database. Demographic characteristics, clinical manifestations, laboratory, radiological, histological and treatment data were collected from medical records during follow-up. RESULTS: A total of 138 patients with cSLE, diagnosed between 1971 and 2015, were included. With a median follow-up of 15.4 [9.6-22.4] years, 51% of patients had a SLICC-Damage Index score ≥ 1 at last follow-up with the musculoskeletal, cutaneous, renal, neurological, and cardiovascular damage being the most common manifestations. The proportion of patients with a SLICC-DI score ≥ 1 increased significantly with the duration of the follow-up (p< 0.001). On multivariate analysis, duration of follow-up was associated with increased risk of cumulative damage (OR 1.08, 95% CI 1.01, 1.15, p= 0.035). At the last visit, 34% of patients still had active disease with a SLEDAI score of ≥ 6. On multivariate analysis, Sub-Saharan African ethnicity was associated with 7-fold increased odds of having active disease at the last visit compared with Caucasians (OR 7.44, 95% CI 2.24, 24.74, p= 0.0002). CONCLUSION: The prevalence of damage remains high in patients with cSLE even when the diagnosis of c-SLE has been made in the recent decades.

Immunoglobulin (Ig)M antibodies to proteinase 3 in granulomatosis with polyangiitis and microscopic polyangiitis.

Anti-neutrophil cytoplasmic antibodies (ANCA) appear to play an important role in the pathogenesis of ANCA-associated vasculitis (AAV). However, ANCA alone are not sufficient to generate disease, and some evidence suggests that infectious triggers may serve as inciting events for AAV disease activity. Antibodies of the immunoglobulin (Ig)M isotype often serve as markers of recent infection, and IgM ANCA have been identified previously in patients with AAV, although the frequency and clinical relevance of IgM ANCA is not well established. We sought to characterize IgM ANCA more clearly by creating a novel enzyme-linked immunosorbent assay (ELISA) for IgM antibodies to proteinase 3 [IgM proteinase 3 (PR3)-ANCA], which we applied to two large, clinically well-characterized trial cohorts of patients with granulomatosis with polyangiitis and microscopic polyangiitis. In the first cohort, IgM PR3-ANCA occurred with a frequency of 15·0%, and were associated with a higher degree of disease severity and a trend towards a higher rate of alveolar haemorrhage (29·6 versus 15·7%, P = 0·10). Analysis of follow-up samples in this cohort showed that the presence of IgM PR3-ANCA was transient, but could recur. In the second cohort, IgM PR3-ANCA occurred with a frequency of 41·1%, and were also associated with a higher degree of disease severity. A higher rate of alveolar haemorrhage was observed among those with IgM PR3-ANCA (45·3 versus 15·8%; P < 0·001). The association of transient IgM PR3-ANCA with an acute respiratory manifestation of AAV suggests a possible link between an infectious trigger and AAV disease activity.

[From myxomas of the skin to LVAD implantation : A 28-year-old female patient with Carney complex]. / Von Hautmyxomen zur LVAD-Implantation : Eine 28-jährige Patientin mit Carney-Komplex.

Multiple skin lesions, endocrine dysfunction and cardiac myxomas are characteristic symptoms of Carney complex. This case report gives an overview about the major and minor criteria of Carney complex and presents the course of a female patient who developed severe cardiac insufficiency with multiple organ failure because of recurring heart operations leading to implantation of a left ventricular assist device (LVAD).

ECG-gated coronary angiography enables submillisievert imaging in invasive cardiology.

BACKGROUND: The median dose area products (DAP) and effective doses (ED) of patients arising from coronary angiography (CA) are considerable: According the 2013 National German Registry, they amount to 19.8 Gy × cm(2) and 4.0 mSv, respectively. METHODS: We investigated the feasibility of prospective electrocardiogram (ECG)-gated coronary angiography (CA)-a novel technique in invasive cardiology-with respect to possible reduction in irradiation effects. Instead of universally fix-rated radiographic acquisition within 7.5-15 frames/s, one single frame/heartbeat was triggered toward the diastolic moment immediately before atrial contraction (77 % of ECG-RR interval) most likely to provide motion-free and hence optimized resolution of the coronary tree. For 200 patients (body mass index 27.8 kg/m(2), age 67.5 years, male 55 %, 68 bpm) undergoing ECG-gated CA, we measured various median (interquartile range) parameters for radiation exposure. RESULTS: The total DAP was 0.64 (0.46-1.00), radiographic fraction was 0.30 (0.19-0.43), and fluoroscopic fraction was 0.35 (0.21-0.57) Gy × cm(2). Radiographic imaging occurred within 21.7 s (17.1-26.3), with 25 frames (20-30) over the course of 7 runs (6-8). Fluoroscopy time was 119 s (94-141). Radiographic DAP was 12.6 mGy × cm(2)/frame and 13.8 mGy × cm(2)/s. Fluoroscopic DAP was 0.8 mGy × cm(2)/pulse and 3.1 mGy × cm(2)/s. Patient reference point air kerma was 17.0 mGy (11.1-28.1) and contrast volume was 70 ml (60-85). CONCLUSION: In conclusion, invasive ECG-gated coronary imaging is feasible in clinical routine and enables patient EDs of approx. 3 % of typical values in invasive cardiology: 0.13 mSv (0.09-0.20).

Latest-generation catheterization systems enable invasive submillisievert coronary angiography.

BACKGROUND: The radiation risk of patients undergoing invasive cardiology remains considerable and includes skin injuries and cancer. To date, submillisievert coronary angiography has not been considered feasible. PATIENTS AND METHODS: In 2011, we compared results from 100 consecutive patients undergoing elective coronary angiography using the latest-generation flat-panel angiography system (FPS) with results from examinations by the same operator using 106 historic controls with a conventional image-intensifier system (IIS) that was new in 2002. RESULTS: The median patient exposure parameters were measured as follows: dose-area product (DAP) associated with radiographic cine acquisitions (DAP(R)) and fluoroscopy (DAP(F)) scenes, radiographic frames and runs, and cumulative exposure times for radiography and fluoroscopy. On the FPS as compared to the traditional IIS, radiographic detector entrance dose levels were reduced from 164 to 80 nGy/frame and pulse rates were lowered from 12.5/s to 7.5/s during radiography and from 25/s to 4/s during fluoroscopy. The cardiologist's performance patterns remained comparable over the years: fluoroscopy time was constant and radiography time even slightly increased. Overall patient DAP decreased from 7.0 to 2.4 Gy × cm(2); DAP(R), from 4.2 to 1.7 Gy × cm(2); and DAP(F), from 2.8 to 0.6 Gy × cm(2). Time-adjusted DAP(R)/s decreased from 436 to 130 mGy × cm(2) and DAP(F)/s, from 21.6 to 4.4 mGy × cm(2). Cumulative patient skin dose with the FPS amounted to 67 mGy, and the median (interquartile range) of effective dose was 0.5 (0.3 … 0.7) mSv. CONCLUSION: Consistent application of radiation-reducing techniques with the latest-generation flat-panel systems enables submillisievert coronary angiography in invasive cardiology.

[Diagnosis of systolic and diastolic heart failure]. / Diagnostik der systolischen und diastolischen Herzinsuffizienz.

In this review, heart failure is confined to etiologies not due to rhythm disturbances or valvular heart disease. Besides measurement of natriuretic peptides, echocardiography is established as an important diagnostic procedure. Echocardiography is especially helpful in discriminating between heart failure with preserved ejection fraction (HF-PEF) and reduced ejection fraction (HF-REF). Because of its ease to be performed, the 6 min walk test continues to be a standard diagnostic procedure. Cardiopulmonary exercise testing provides more detailed information regarding differential diagnostic and prognostic considerations.

Treatment of acute decompensation of maple syrup urine disease in adult patients with a new parenteral amino-acid mixture.

BACKGROUND: Acute decompensation of maple syrup urine disease (MSUD) is usually treated by enteral feeding with an amino-acid mixture without leucine (Leu), valine or isoleucine. However, its administration is ineffective in cases of gastric intolerance and some adult patients refuse enteral feeding via a nasogastric tube. We developed a new parenteral amino-acid mixture for patients with MSUD. METHODS: Seventeen decompensation episodes in four adult patients with MSUD treated with a parenteral amino-acid mixture (group P) were compared to 18 previous episodes in the same patients treated by enteral feeding (group E). RESULTS: The mean Leu concentration at presentation was similar in the groups P and E (1196.9 µmol/L and 1212.2 µmol/L, respectively). The mean decrease in the Leu concentration during the first 3 days of hospitalisation was significantly higher in group P than group E (p = 0.0026); there were no side effects. The mean duration of hospitalisation was similar (4 vs. 4.5 days, p = NS). No patient in group P deteriorated whereas one patient in group E required dialysis. CONCLUSION: This new parenteral amino-acid mixture is safe and allows efficient Leu concentration decrease during acute MSUD decompensation episodes in adults. Its use avoids the need for nasogastric tube insertion.

Short-chain fatty acids inhibit the activation of T lymphocytes and myeloid cells and induce innate immune tolerance.

The intestinal microbiota contributes to gut immune homeostasis, where short-chain fatty acids (SCFAs) function as the major mediators. We aimed to elucidate the immunomodulatory effects of acetate, propionate, and butyrate. With that in mind, we sought to characterise the expression of SCFA receptors and transporters as well as SCFAs' impact on the activation of different immune cells. Whereas all three SCFAs decreased tumour necrosis factor (TNF)-α production in activated T cells, only butyrate and propionate inhibited interferon (IFN)-γ, interleukin (IL)-17, IL-13, and IL-10 production. Butyrate and propionate inhibited the expression of the chemokine receptors CCR9 and CCR10 in activated T- and B-cells, respectively. Similarly, butyrate and propionate were effective inhibitors of IL-1ß, IL-6, TNF-α, and IL-10 production in myeloid cells upon lipopolysaccharide and R848 stimulation. Acetate was less efficient at inhibiting cytokine production except for IFN-α. Moreover, SCFAs inhibited the production of IL-6 and TNF-α in monocytes, myeloid dendritic cells (mDC), and plasmacytoid dendritic cells (pDC), whereas acetate effects were relatively more prominent in pDCs. In monocytes and mDCs, acetate was a less efficient inhibitor, but it was equally effective in inhibiting pDCs activation. We also studied the ability of SCFAs to induce trained immunity or tolerance. Butyrate and propionate - but not acetate - prevented Toll-like receptor-mediated activation in SCFA-trained cells, as demonstrated by a reduced production of IL-6 and TNF-α. Our findings indicate that butyrate and propionate are equally efficient in inhibiting the adaptive and innate immune response and did not induce trained immunity. The findings may be explained by differential SCFA receptor and transporter expression profiles of the immune cells.

Regulation of E-cadherin-mediated adhesion by muscarinic acetylcholine receptors in small cell lung carcinoma.

We present the first evidence that adhesion mediated by a member of the cadherin gene family can be regulated by a G protein-coupled receptor. We show that activating the M3 muscarinic acetylcholine receptor (mAChR) rapidly induces E-cadherin-mediated adhesion in a small cell lung carcinoma (SCLC) cell line. This response is inhibited by E-cadherin antibodies, and does not occur in another SCLC cell line which expresses functional mAChR but reduced levels of E-cadherin. Protein kinase C may be involved, since phorbol 12-myristate 13-acetate also induces E-cadherin-mediated aggregation. Immunofluorescence analyses indicate that mAChR activation does not grossly alter E-cadherin surface expression or localization at areas of cell-cell contact, suggesting mAChR activation may increase E-cadherin binding activity. Our findings suggest that G protein-coupled receptors may regulate processes involving cadherin-mediated adhesion, such as embryonic development, neurogenesis, and cancer metastasis.

Glycosylation of proteinase 3 (PR3) is not required for its reactivity with antineutrophil cytoplasmic antibodies (ANCA) in Wegener's granulomatosis.

OBJECTIVE: The glycosylation status of autoantigens appears to be crucial for the pathogenesis of some autoimmune diseases, since carbohydrates play a crucial role in the distinction of self from non-self. Proteinase 3 (PR3), the main target antigen for anti-neutrophil cytoplasmic antibodies (ANCA) in patients with Wegener's granulomatosis (WG), contains two Asn-linked glycosylation sites. The present study explores the influence of the glycosylation status of PR3 on the PR3 recognition by ANCA in a well characterized population of patients with WG. METHODS: Forty-four patients with WG (459 serum samples) who participated in a multicenter randomized trial, were tested by capture ELISA for ANCA against PR3 and deglycosylated recombinant variants of PR3. RESULTS: The patients were followed for a median of 27 months, and the median number of serum samples per patient was 10. At baseline, the correlation between the levels of ANCA against PR3 and against all the deglycosylated recombinant variants of PR3 were greater than 0.94 (?<0.001 for all the comparisons). Longitudinal analyses comparing the levels of ANCA against PR3 versus all the deglycosylated recombinant variants of PR3, using linear mixed models, showed no significant statistical differences (rho >or=0.90 in all cases). CONCLUSION: The glycosylation status of PR3 has no impact on its recognition by ANCA in WG.

Preoperative platelet transfusions to reverse antiplatelet therapy for urgent non-cardiac surgery: an observational cohort study.

Essentials An increasing number of patients requiring surgery receive antiplatelet therapy (APT). We analyzed 181 patients receiving presurgery platelet transfusions to reverse APT. No coronary thrombosis occurred after platelet transfusion. This justifies a prospective trial to test preoperative platelet transfusions to reverse APT. SUMMARY: Background Patients receiving antiplatelet therapy (APT) have an increased risk of perioperative bleeding and cardiac adverse events (CAE). Preoperative platelet transfusions may reduce the bleeding risk but may also increase the risk of CAE, particularly coronary thrombosis in patients after recent stent implantation. Objectives To analyze the incidence of perioperative CAE and bleeding in patients undergoing non-cardiac surgery using a standardized management of transfusing two platelet concentrates preoperatively and restart of APT within 24-72 h after surgery. Methods A cohort of consecutive patients on APT treated with two platelet concentrates before non-cardiac surgery between January 2012 and December 2014 was retrospectively identified. Patients were stratified by the risk of major adverse cardiac and cerebrovascular events (MACCE). The primary objective was the incidence of CAE (myocardial infarction, acute heart failure and cardiac troponine T increase). Secondary objectives were incidences of other thromboembolic events, bleedings, transfusions and mortality. Results Among 181 patients, 88 received aspirin, 21 clopidogrel and 72 dual APT. MACCE risk was high in 63, moderate in 103 and low in 15 patients; 67 had cardiac stents. Ten patients (5.5%; 95% CI, 3.0-9.9%) developed a CAE (three myocardial infarctions, four cardiac failures and three troponin T increases). None was caused by coronary thrombosis. Surgery-related bleeding occurred in 22 patients (12.2%; 95% CI, 8.2-17.7%), making 12 re-interventions necessary (6.6%; 95% CI, 3.8-11.2%). Conclusion Preoperative platelet transfusions and early restart of APT allowed urgent surgery and did not cause coronary thromboses, but non-thrombotic CAEs and re-bleeding occurred. Randomized trials are warranted to test platelet transfusion against other management strategies.

Ontogenic and nutritional regulation of steroid receptor and IGF-I transcript abundance in the prepubertal heifer mammary gland.

In prepubertal cattle, mammary development is characterized by the growth of an epithelial-rich parenchyma (PAR) into the mammary fat pad (MFP). This proliferation and accumulation of mammary epithelial cells require estrogen. Paradoxically, both epithelial cell proliferation and PAR accumulation rate decline with rising plasma estrogen as puberty approaches. The possibility that variation in abundance of estrogen receptors (ERs) in PAR or MFP accounts for a portion of these effects has not been examined in cattle. Additionally, we recently demonstrated that MFP is highly responsive to exogenous estrogen, suggesting that this tissue may play a role in coordinating estrogen's effects on PAR; however, the developing bovine MFP has yet to be studied in detail. To address these hypotheses, Holstein heifers were assigned to planes of nutrition supporting body growth rates of 950 (E) or 650 (R) g/day and harvested every 50 kg from 100 to 350 kg body weight (BW). Post-harvest, their mammary glands were dissected into PAR and MFP compartments. Transcript abundance of genes encoding members of the ER family (ERalpha, ERbeta, and estrogen-related receptor alpha-1 (ERRalpha)) and estrogen-responsive genes (IGF-I and progesterone receptor (PR)) were measured in both mammary compartments by quantitative real-time RT-PCR. Significant expression was detected for all genes in both compartments, with the exception of the ERbeta gene. Transcript abundance of both ERalpha and IGF-I decreased linearly with increasing BW within both compartments. ERRalpha and PR expressions decreased with increasing BW in PAR but not in MFP. Nutrition stimulated ERalpha and ERRalpha expression in the PAR but had no effect on IGF-I or PR in either PAR or MFP. Overall, ERalpha and IGF-I transcript abundance are consistent with the drop in mammary epithelial cell proliferation and PAR accretion observed over development, but do not support a negative effect of nutrition on PAR growth.

[Progressive multifocal leukoencephalopathy in a non-AIDS patient: high efficiency of combined cytarabine and cidofovir]. / Leucoencéphalite multifocale progressive en dehors du sida: efficacité de l'association cytarabine-cidofovir.

INTRODUCTION: Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the central nervous system, occurring in immunocompromised patients. Treatment, not codified to date, is more often inefficient with a rapid and fatal deterioration. CASE RECORD: A 48-year-old woman, treated with immunosuppressant agents for systemic lupus, presented with PML mimicking neurolupus flare. A complete remission was obtained with cytarabine and cidofovir. CONCLUSION: Combined cytarabine and cidofovir appears a promising therapeutic option in PML associated with autoimmune systemic disorders.

[Urinary erythropoietin excretion: an unknown cause of anemia during nephrotic syndrome]. / La fuite urinaire d'érythropoïétine: une cause méconnue d'anémie au cours des syndromes néphrotiques.

INTRODUCTION: Nephrotic syndrome (NS) is characterized by an excessive urinary protein excretion. CASE RECORD: A woman, followed-up for NS, present progressive anemia, with no simple explanation. Plasma EPO is low with significant urinary EPO excretion. Treatment with EPO corrects hemoglobin level. CONCLUSION: EPO deficiency due to excessive urinary excretion is an underestimated cause of anemia during NS.

[Prevention of infections in adults and adolescents with systemic lupus erythematosus: Guidelines for the clinical practice based on the literature and expert opinion]. / Prévention des infections au cours du lupus systémique chez l'adulte et l'adolescent : élaboration de recommandations pour la pratique clinique, à partir d'une analyse de la littérature et de l'avis d'experts.

PURPOSE: To develop French recommendations about the management of vaccinations, the screening of cervical cancer and the prevention of pneumocystis pneumonia in systemic lupus erythematosus (SLE). METHODS: Thirty-seven experts qualified in internal medicine, rheumatology, dermatology, nephrology and pediatrics have selected recommendations from a list of proposition based on available data from the literature. For each recommendation, the level of evidence and the level of agreement among the experts were specified. RESULTS: Inactivated vaccines do not cause significant harm in SLE patients. Experts recommend that lupus patient should receive vaccinations accordingly to the recommendations and the schedules for the general public. Pneumococcal vaccination is recommended for all SLE patients. Influenza vaccination is recommended for immunosuppressed SLE patients. Live attenuated vaccines should be avoided in immunosuppressed patients. Yet, recent works suggest that they can be considered in mildly immunosuppressed patients. Experts have recommended a cervical cytology every year for immunosuppressed patients. No consensus was obtained for the prevention of pneumocystis pneumonia. CONCLUSION: These recommendations can be expected to improve clinical practice uniformity and, in the longer term, to optimize the management of SLE patients.

Kidney transplantation process in Brazil represented in business process modeling notation.

Kidney transplantation is considered to be the best treatment for people with chronic kidney failure, because it improves the patients' quality of life and increases their length of survival compared with patients undergoing dialysis. The kidney transplantation process in Brazil is defined through laws, decrees, ordinances, and resolutions, but there is no visual representation of this process. The aim of this study was to analyze official documents to construct a representation of the kidney transplantation process in Brazil with the use of business process modeling notation (BPMN). The methodology for this study was based on an exploratory observational study, document analysis, and construction of process diagrams with the use of BPMN. Two rounds of validations by specialists were conducted. The result includes the kidney transplantation process in Brazil representation with the use of BPMN. We analyzed 2 digital documents that resulted in 2 processes with 45 total of activities and events, 6 organizations involved, and 6 different stages of the process. The constructed representation makes it easier to understand the rules for the business of kidney transplantation and can be used by the health care professionals involved in the various activities within this process. Construction of a representation with language appropriate for the Brazilian lay public is underway.

Role of Experience, Leadership and Individual Protection in the Cath Lab--A Multicenter Questionnaire and Workshop on Radiation Safety.

PURPOSE: Radiation exposure in invasive cardiology remains considerable. We evaluated the acceptance of radiation protective devices and the role of operator experience, team leadership, and technical equipment in radiation safety efforts in the clinical routine. MATERIALS AND METHODS: Cardiologists (115 from 27 centers) answered a questionnaire and documented radiation parameters for 10 coronary angiographies (CA), before and 3.1 months after a 90-min. mini-course in radiation-reducing techniques. RESULTS: Mini-course participants achieved significant median decreases in patient dose area products (DAP: from 26.6 to 13.0 Gy × cm(2)), number of radiographic frames (-29%) and runs (-8%), radiographic DAP/frame (-2%), fluoroscopic DAP/s (-39%), and fluoroscopy time (-16%). Multilevel analysis revealed lower DAPs with decreasing body mass index (-1.4 Gy × cm(2) per kg/m(2)), age (-1.2 Gy × cm(2)/decade), female sex (-5.9 Gy × cm(2)), participation of the team leader (-9.4 Gy × cm(2)), the mini-course itself (-16.1 Gy × cm(2)), experience (-0.7 Gy × cm(2)/1000 CAs throughout the interventionalist's professional life), and use of older catheterization systems (-6.6 Gy × cm(2)). Lead protection included apron (100%), glass sheet (95%), lengthwise (94%) and crosswise (69%) undercouch sheet, collar (89%), glasses (28%), cover around the patients' thighs (19%), foot switch shield (7%), gloves (3%), and cap (1%). CONCLUSION: Radiation-protection devices are employed less than optimally in the clinical routine. Cardiologists with a great variety of interventional experience profited from our radiation safety workshop - to an even greater extent if the interventional team leader also participated. KEY POINTS: Radiation protection devices are employed less than optimally in invasive cardiology. The presented radiation-safety mini-course was highly efficient. Cardiologists at all levels of experience profited from the mini-course - considerably more so if the team leader also took part. Interventional experience was less relevant for radiation reduction. Consequently both fellows and trainers should be encouraged to practice autonomy in radiation safety.

[Screening and management of cardiovascular risk factors in systemic lupus erythematosus: Recommendations for clinical practice based on the literature and expert opinion]. / Dépistage et prise en charge du risque cardiovasculaire au cours du lupus systémique : élaboration de recommandations pour la pratique clinique, à partir d'une analyse de la littérature et de l'avis d'experts.

PURPOSE: To develop French recommendations about screening and management of cardiovascular risk factors in systemic lupus erythematosus (SLE). METHODS: Thirty-nine experts qualified in internal medicine, rheumatology and nephrology have selected recommendations from a list developed based on evidence from the literature. For each recommendation, the level of evidence and the level of agreement among the experts were specified. RESULTS: Experts recommended an annual screening of cardiovascular risk factors in SLE. Statins should be prescribed for primary prevention in SLE patients based on the level of LDL-cholesterol and the number of cardiovascular risk factors, considering SLE as an additional risk factor. For secondary prevention, experts have agreed on an LDL-cholesterol target of <0.7 g/L. Hypertension should be managed according to the 2013 European guidelines, using renin-angiotensin system blockers as first line agents in case of renal involvement. Aspirin can be prescribed in patients with high cardiovascular risk or with antiphospholipid antibodies. CONCLUSION: These recommendations about the screening and management of cardiovascular risk factors in SLE can be expected to improve clinical practice uniformity and, in the longer term, to optimize the management of SLE patients.

Cloning and functional expression of the murine homologue of proteinase 3: implications for the design of murine models of vasculitis.

Anti-neutrophil cytoplasmic autoantibodies recognizing conformational epitopes (c-ANCA) of proteinase 3 (PR3) from azurophil granules are a diagnostic hallmark in Wegener's granulomatosis (WG). Because a functional PR3 homologue has not been identified in rodents, it is difficult to assess immunopathological responses in rats or mice immunized with patients' derived c-ANCA or human PR3. Here we report the full length cDNA cloning and functional expression of murine PR3 in HMC-1 cells. Recombinant murine PR3 shows highly similar substrate specificities towards synthetic peptides and is inhibited by human alpha1-proteinase inhibitor like human PR3. However, neither human c-ANCA, rabbit sera nor mouse monoclonal antibodies to human PR3 recognize the murine homologue. Consequently, it is unlikely that disease observed in mice after immunization with c-ANCA or human PR3 is caused by pathogenic antibodies directed against mouse PR3. Recombinant human-mouse chimaeric variants will be a valuable new tool to localize the disease-specific immunodominant epitopes in human PR3.

Recombinant human proteinase 3, the Wegener's autoantigen, expressed in HMC-1 cells is enzymatically active and recognized by c-ANCA.

We developed a stable expression system for conformationally intact recombinant human PR3 (rPR3) using the human mast cell line HMC-1. Like in U937 cells, the rPR3 is processed from a 34 kDa precursor to the 29 kDa mature form, primarily as the result of oligosaccharide trimming. The rPR3 binds [3H]DFP and hydrolyzes the substrate N-methoxysuccinyl-Ala-Ala-Pro-Val-pNA. The enzymatic activity is inhibited by greater than 95% by alpha 1-PI. The rPR3 and the enzymatically inactive mutant rPR3-S176A are both packaged in granules. Thus, proteolytic autoprocessing is not required for PR3's targeting to granules. This rPR3 is the first to be recognized by most c-ANCA from WG patients and all anti-PR3 ANCA that were detected by standard anti-PR3 specific ELISA. This expression system for rPR3 represents a versatile tool for the analysis of its intracellular processing, structure-function relationships and interaction with autoantibodies.