Myeloperoxidase anti‐neutrophil cytoplasmic antibody affinity is associated with the formation of neutrophil extracellular traps in the kidney and vasculitis activity in myeloperoxidase anti‐neutrophil cytoplasmic antibody‐associated microscopic polyangiitis

Anti‐neutrophil cytoplasmic antibody (ANCA) is associated with small‐vessel vasculitis particularly in the kidneys and can induce the formation of neutrophil extracellular traps (NETs) from primed neutrophils. Recently we have reported that the induction of NETs correlates with ANCA affinity for myeloperoxidase (MPO) and disease activity in patients with MPO‐ANCA‐associated microscopic polyangiitis. To investigate whether MPO‐ANCA affinity is associated with the formation of NETs in vivo, we examined the occurrence of NETs in the renal tissues of patients with MPO‐ANCA‐associated microscopic polyangiitis and ANCA affinity by double immunofluorescence staining for NET components of citrullinated histone, MPO and PAD4 and by ELISA competition with MPO, respectively. We divided 30 MPO‐ANCA‐associated microscopic polyangiitis patients into 2 groups based on their ANCA affinity levels (IC₅₀ for the high: 0.11 ± 0.04 µg/mL (Group1) and IC₅₀ for the low: 0.66 ± 0.24 µg/mL (Group2)). Group1 showed a higher Birmingham vasculitis activity score (15.6 ± 5.7) and 73% of the patients presented clinically with rapidly progressive glomerulonephritis and histologically with focal/crescentic glomerulonephritis (GN). Group 2 showed a lower Birmingham vasculitis activity score (9.2 ± 4.9) and 73% of the patients presented clinically with chronic renal failure and histologically with mixed/sclerotic GN. Group 1 showed a much higher occurrence of NETs than Group 2. Our findings indicate that ANCA affinity was associated with the in vivo formation of NETs, which might be involved in the pathophysiology of patients with MPO‐ANCA‐associated microscopic polyangiitis.     

Regulatory T cells in immune‐mediated renal disease

Regulatory T cells (Tregs) are CD4+ T cells that can suppress immune responses by effector T cells, B cells and innate immune cells. This review discusses the role that Tregs play in murine models of immune‐mediated renal diseases and acute kidney injury and in human autoimmune kidney disease (such as systemic lupus erythematosus, anti‐glomerular basement membrane disease, anti‐neutrophil cytoplasmic antibody‐associated vasculitis). Current research suggests that Tregs may be reduced in number and/or have impaired regulatory function in these diseases. Tregs possess several mechanisms by which they can limit renal and systemic inflammatory immune responses. Potential therapeutic applications involving Tregs include in vivo induction of Tregs or inducing Tregs from naïve CD4+ T cells or expanding natural Tregs ex vivo, to use as a cellular therapy. At present, the optimal method of generating a phenotypically stable pool of Tregs with long‐lasting suppressive effects is not established, but human studies in renal transplantation are underway exploring the therapeutic potential of Tregs as a cellular therapy, and if successful may have a role as a novel therapy in immune‐mediated renal diseases.     

Vasculitic renal disease*

SUMMARY: The kidney may be involved in several forms of systemic vasculitis, particularly those affecting small‐calibre blood vessels. Hence, the majority of cases involve patients with Wegener's granulomatosis, Churg‐Strauss syndrome or microscopic polyangiitis. Anti‐neutrophil cytoplasmic antibodies (ANCA) are found in the majority of these patients and their detection has increased the sensitivity and specificity of diagnosis. However, the role of ANCA in the pathogenesis of these lesions remains uncertain. Moreover, the approach to treatment, both in terms of induction and maintenance of remission, remains problematic. This brief review discusses aspects of ANCA and current approaches to management.     

原发性小血管炎肺脏受累

目的　探讨原发性小血管炎肺脏受累的诊断和治疗。方法　对 15例原发性小血管炎伴肺脏受累患者的临床资料进行分析。结果　肺脏是原发性小血管炎常受累脏器之一 ,约占原发性小血管炎患者 6 0 % (15 / 2 5例 )。肺脏受累的临床表现有咳嗽、哮喘 ,不同程度咯血 ,胸片呈现多样化。由于肺泡广泛出血导致大咯血窒息及严重低氧血症是肺脏受累的严重并发症 ,若能及时采用血浆置换疗法和 (或 )激素、细胞毒冲击治疗 ,肺出血可迅速吸收。动态观察发现不少病人胸片及临床症状可呈戏剧性变化 ,临床危重症得以改善。结论　原发性小血管炎伴肺脏受累是常见的。适当的治疗可改善其预后。     

Long‐term outcome of antineutrophil cytoplasmic antibody‐associated small vessel vasculitis after renal transplantation

The survival after renal transplantation of patients with antineutrophil cytoplasmic antibody (ANCA)‐associated to systemic vasculitis is as good as in other diseases, although most of the reports are based on small numbers of patients. Furthermore, it is not known whether comorbidities (cardiovascular [CV] disease and cancer) are more frequent than in general population. We report our experience and the analysis of the published data on this topic. The outcome after transplantation in 49 patients with ANCA‐associated small vessel vasculitis was compared with a control group. The relapse rate of vasculitis was 0.01 per patient per year. Comparison with the control patients revealed no difference in long‐term outcome, CV mortality or incidence of malignancies. In the published literature, patients with ANCA at transplantation and with Wegener's granulomatosis are at greater risk of relapse. Taking our own results together with the review of the literature, we conclude that patient and graft survival rates compare favorably with those in control group that the recurrence rate is very low and that there is no increase in the incidence of cancer or in CV mortality. Patients with ANCA at transplantation and with Wegener's granulomatosis have a higher relapse rate.     

Mycophenolate mofetil versus cyclophosphamide for inducing remission of ANCA vasculitis with moderate renal involvement.

OBJECTIVE: We performed a single-centre non-blinded clinical trial to compare the clinical efficacies of mycophenolate mofetil (MMF) and intermittent cyclophosphamide (CTX) pulse therapy as induction treatments in patients with antineutrophil cytoplasmic antibody (ANCA) vasculitis (AAV) and moderate renal involvement. METHODS: Patients with active AAV and serum creatinine <500 micromol/L received either MMF treatment (MMF group) or monthly CTX pulse therapy (CTX group) for 6 months. Disease activity was assessed using the Birmingham Vasculitis Activity Score (BVAS). The disease activity, remission rate, renal function and adverse reactions were compared between the two groups. RESULTS: A total of 35 patients (15 male, 20 female: aged 49.1 +/- 12.2 years) were enrolled, with 18 in the MMF group and 17 in the CTX group. Of the 35 patients, 28 were MPO-ANCA positive and 2 were PR3-ANCA positive. Four patients were lost to follow-up in the CTX group. At Month 6, BVAS scores were much lower in the MMF group than in the CTX group (0.2 +/- 0.89 versus 2.6 +/- 1.7, P < 0.05). In the intent-to-treatment analysis, 14 of 18 patients (77.8%) treated with MMF and 8 of 17 patients receiving CTX (47.1%) had complete remission with an absolute difference of 30.7%. Eight of 18 patients (44.4%) in the MMF group and 2 of 17 patients (15.4%) in the CTX group recovered renal function. Serum ANCA decreased to normal in 41.7% of patients in the MMF group and in 16.7% in the CTX group. Side effects in the MMF group were pneumonia (1), herpes zoster (1) and gastrointestinal symptoms (2), and in the CTX group were leukocytopenia (1), gastrointestinal distress (4) and pneumonia (1). CONCLUSION: Our study suggests that MMF effectively ameliorates disease activity and considerably improves renal function in patients with AAV. Further large-scale multicentre prospective randomized controlled trials will be needed to confirm these findings.     

中性粒细胞胞外诱捕网与炎性疾病的研究进展

目的探讨中性粒细胞胞外诱捕网(NETs)对炎性疾病的调控机制,旨在为相关炎性疾病的治疗提供指导。方法复习近年来国内外有关NETs和炎性疾病之间关系的相关文献并加以综述。结果 NETs在脓毒症、抗中性粒细胞胞浆抗体(ANCA)相关性血管炎、急性胰腺炎、炎症性肠病等炎性疾病中发挥着重要作用,与疾病发生、发展或活动性有关。通过调控NETs形成通路,降低NETs的产生,能最终减轻疾病的炎症病情。结论 NETs参与了脓毒症、ANCA相关性血管炎、急性胰腺炎、炎症性肠病等炎性疾病的病程,但其调控机制仍有待更深入的探究及临床验证。     

ANCA-associated vasculitis with renal involvement: an outcome analysis.

BACKGROUND: The anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides are a group of heterogeneous diseases. This study was undertaken to investigate the outcome of Wegener's granulomatosis (WG), microscopic polyangiitis (MPA) and renal-limited vasculitis (RLV). Furthermore, we analysed the differences in patients with proteinase 3-ANCA (PR3-ANCA) and those with myeloperoxidase-ANCA (MPO-ANCA), which have not been assessed in a homogeneously treated group of patients with renal involvement. METHODS: In this retrospective analysis, 80 patients with a new diagnosis of WG, MPA or RLV with biopsy-proven renal involvement were followed over a median of 46.7 months (range: 0.8-181.9 months). All patients had induction treatment with cyclophosphamide and oral corticosteroids. RESULTS: At the end of follow-up, 23% were dependent on dialysis. Renal survival was significantly worse in patients with WG compared with patients with MPA or RLV (P = 0.04). A higher rate of end-stage renal disease (ESRD) was noticed in PR3-ANCA- vs MPO-ANCA-positive patients. A total of 21 patients (26%) died. Predictors of patient mortality were development of ESRD, older age and the maximum creatinine in the first month. Mortality was found to be higher in patients with WG and was significantly higher in PR3-ANCA-positive cases (P = 0.02). The relative risk of death was 9.32 times higher in PR3-ANCA- vs MPO-ANCA-positive patients. CONCLUSIONS: Our data underscore the pathogenetic potential of ANCA by demonstrating a more aggressive disease state and a poorer outcome in patients with PR3-ANCA.     

Anti-non-Gal porcine endothelial cell antibodies in acute humoral xenograft rejection of hDAF-transgenic porcine hearts in cynomolgus monkeys

Abstract: Background: Anti‐Galα1–3Gal (Gal) antibodies play a major role in hyperacute rejection and acute humoral xenograft rejection (AHXR) in porcine‐to‐nonhuman primate transplantation. The role of anti‐non‐Gal antibodies in AHXR is less well defined. Methods: Eleven cynomolgus monkeys received a heterotopic heart transplant from a human decay‐accelerating factor transgenic pig, and maintenance immunosuppression with cyclosporin A or tacrolimus, steroids, mycophenolate sodium or mycophenolate mofetil, and in 10 animals the Gal‐containing soluble glycoconjugate GAS914. Six ended with AHXR (6 to 78 day survival) and five did not show AHXR (9 to 36 day survival). Anti‐Gal antibodies were depleted in vivo with GAS914, or in vitro with Gal‐coated Sepharose beads. IgM‐ and IgG‐class anti‐non‐Gal antibodies in serum depleted of anti‐Gal antibodies were measured by flow cytometry using porcine endothelial target cells. Results: Compared with pre‐transplant values, all six recipients with AHXR showed a substantially higher level of anti‐non‐Gal IgM antibodies at rejection; in five animals there was also an increase in IgG‐class antibodies. There was no relevant change in recipients without AHXR. AHXR at time of cessation of heart contraction could be preceeded by a steady increase in antibody level starting 2 to 3 weeks earlier. Conclusions: AHXR is invariably associated with increased circulating anti‐non‐Gal antibodies. These antibodies are not observed in recipients without AHXR, and five of six recipients with AHXR were adequately depleted of anti‐Gal antibodies by maintenance GAS914. This indicates that anti‐non‐Gal antibodies play a significant role in the pathogenesis of AHXR. Also, the assessment of these antibodies could be used as an early monitor of AHXR.     

ANCA相关性血管炎肾脏及其他系统损害的临床和病理与预后的相关研究

目的探讨抗中性粒细胞胞浆抗体相关性血管炎(antineutrophil cytoplasmic antibodyassociated vasculitis,AAV)肾损害及其他系统损害患者的临床和病理特征,并对其预后及其相关危险因素进行分析。方法选择1995年9月至2009年9月内蒙古自治区人民医院明确诊断为AVV内蒙古籍患者123例,血清抗中性粒细胞胞浆抗体(antineutrophil cytoplasmic antibody,ANCA)阳性,根据检测结果将患者分为胞质型(C-ANCA)阳性组和核周型(P-ANCA)阳性组,进行临床、实验室、病理及预后相关因素进行分析。随访终点为死亡或终末期肾衰竭进入规律肾脏替代治疗,平均随访时间5年。结果 123例患者中男63例,女60例,男女比例1.05:1,年龄38~82岁,平均年龄(60.0±22.0)岁,50~82岁患者102例(占82.9%)。其中P-ANCA阳性109例,C-ANCA阳性14例。P-ANCA组肾脏、肺脏受累与C-ANCA组相似,消化道、关节、眼损害发生率低于C-ANCA组(P0.05);耳、皮肤、肌肉、神经系统损害2组无统计学差异。123例患者中有62例患者行肾活检,其中细胞性新月体肾炎30例(占48.4%),毛细血管袢坏死12例(占19.4%),细胞伴纤维性新月体形成15例(占24.2%),纤维性新月体伴局灶节段性硬化5例(占8.1%)。对AAV患者进行5年随访,对患者死亡或进入肾脏终末期代替治疗进行相关因素分析:C-ANCA组与P-ANCA组相比,患者死亡与进入终末期替代治疗2组间均无统计学差异(P0.05)。对患者的年龄、性别、ANCA类型、发热、肾衰竭、呼吸衰竭、咯血、脏器受累数目、多脏器衰竭、肺感染因素进行COX回归分析:呼吸衰竭、多脏器衰竭为死亡的相关因素(偏回归分数分别为2.087,1.129,均P0.05)。对患者起病时实验室数据进行回归分析:血肌酐、红细胞沉降率、血浆白蛋白、血红蛋白与终末终点相关。Logistic回归分析,起病的血肌酐及红细胞沉降率是预测患者预后的独立危险因素。结论 AAV以中老年男性多见,PANCA阳性患者较C-ANCA阳性患者,发病率高,受累器官数目多且病程谱广。呼吸衰竭、多脏器衰竭与患者死亡密切相关。患者起病的血肌酐及红细胞沉降率是预测患者预后的独立危险因素。     

Does human leukocyte antigens sensitization matter for xenotransplantation?

The major histocompatibility complex class I and class II human leukocyte antigens (HLA) play a central role in adaptive immunity but are also the dominant polymorphic proteins targeted in allograft rejection. Sensitized patients with high levels of panel‐reactive anti‐HLA antibody (PRA) are at risk of early allograft injury, rejection, reduced allograft survival and often experience prolonged waiting times prior to transplantation. Xenotransplantation, using genetically modified porcine organs, offers a unique source of donor organs for these highly sensitized patients if the anti‐HLA antibody, which places the allograft at risk, does not also enhance anti‐pig antibody reactivity responsible for xenograft rejection. Recent improvements in xenotransplantation efficacy have occurred due to improved immune suppression, identification of additional xenogeneic glycans, and continued improvements in donor pig genetic modification. Genetically engineered pig cells, devoid of the known xenogeneic glycans, minimize human antibody reactivity in 90% of human serum samples. For waitlisted patients, early comparisons of patient PRA and anti‐pig antibody reactivity found no correlation suggesting that patients with high PRA levels were not at increased risk of xenograft rejection. Subsequent studies have found that some, but not all, highly sensitized patients express anti‐HLA class I antibody which cross‐reacts with swine leukocyte antigen (SLA) class I proteins. Recent detailed antigen‐specific analysis suggests that porcine‐specific anti‐SLA antibody from sensitized patients binds cross‐reactive groups present in a limited subset of HLA antigens. This suggests that using modern genetic methods, a program to eliminate specific SLA alleles through donor genetic engineering or stringent donor selection is possible to minimize recipient antibody reactivity even for highly sensitized individuals.     

Anti-laminin auto antibodies in ANCA-associated vasculitis.

BACKGROUND: Endothelial cell damage occurs during vasculitic processes in vivo. With the alteration of the endothelium, exposure to basement membrane components may occur with induction of humoral immunity. METHODS: In the present study, we evaluated the prevalence of antibodies against the basement membrane antigen laminin (LMN) in patients with ANCA-associated systemic vasculitis (AASV), pathologic controls (systemic lupus erythematosus, mixed cryoglobulinaemia, Henoch-Sch?nlein purpura, primary glomerulonephritis) and normal individuals. RESULTS: By ELISA, 21.6% of AASV (16/74) and 10% of pathologic controls (3/30), but only one of the normal controls (2. 8%) had these antibodies (P=0.02). When AASV patients were divided into two groups according to diagnosis and ANCA antigen specificity, antibodies to LMN were found in 27.5% of MPO-ANCA positive microscopic polyangiitis patients (11/40) vs. only 14.7% of PR3-ANCA positive Wegener granulomatosis patients (5/34). There was no correlation between the presence or titre of anti-LMN antibodies and the main clinical and laboratory parameters. CONCLUSION: These results indicate that basement membrane antigens may become immunogenic in patients with AASV, especially in those with MPO-ANCA positivity. These antibodies are most likely the result of endothelial damage secondary to the initial inflammatory process but may well perpetuate further vascular damage in some patients.     

Clinicopathological analysis of Sjogren's syndrome complicated with ANCA associated vasculitis with renal involvement

Objective To investigate the clinical and pathological features of patients with a combination of Sjogren's syndrome (SS) and antineutrophil cytoplasmic antibody (ANCA) associated vasculitis with renal involvement. Methods By searching the Peking Union Medical College Hospital medical database and literature between January 1990 and June 2017, patients had a combination of SS and ANCA associated vasculitis with renal involvement were included. Data of clinical information, autoimmune antibodies, renal manifestations and renal pathology were retrieved and analyzed. Results Eighteen patients were enrolled: 4 from our hospital and 14 from literature. SS was diagnosed no later than ANCA associated vasculitis in all the patients, among which 83.3%(15/18) of patients had extra-glandular and extra-renal organs involved. All the patients were tested positive for myeloperoxidase (MPO)-ANCA, and only two were protein 3 (PR3)-ANCA positive concurrently. The positivity rates of antinuclear antibody (ANA), rheumatoid factor (RF), anti-SSA antibody, and anti-SSB antibody were 83.3%(15/18), 55.6%(10/18), 77.8%(14/18), and 38.9%(7/18), respectively. The renal manifestations were characterized by renal insufficiency with a median serum creatinine of 174 μmol/L, hematuria, moderate proteinuria with a median 24 hour urine protein of 1.70 g, and necrotizing vasculitis with oligo-immune complex and varying degrees of interstitial damage in pathology. Conclusions A combination of Sjogren's syndrome and ANCA associated vasculitis with renal involvement is rare in clinical setting, and almost all of the patients are MPO-ANCA positive, with high probability of ANA positivity and extra-glandular involvement. Physicians should beware of ANCA associated glomerulonephritis in SS patients with inexplicable renal dysfunction and renal biopsy should be carried out in time.