Xiao-yu Jia

Anti-glomerular basement membrane disease: outcomes of different therapeutic regimens in a large single-center Chinese cohort study.

Anti-glomerular basement membrane (GBM) disease usually presents with rapidly progressive glomerulonephritis accompanied by pulmonary hemorrhage. The low incidence and fulminant course of disease preclude a large randomized controlled study to define the benefits of any given therapy. We conducted a retrospective survey of 221 consecutive patients seen from 1998 to 2008 in our hospital, and report here the patient and renal survival and the risk factors affecting the outcomes. Considering the similar clinical features of the patients, we could compare the effects of 3 different treatment regimens: 1) combination therapy of plasmapheresis and immunosuppression, 2) steroids and cytotoxic agents, and 3) steroids alone.The patient and renal survival rates were 72.7% and 25.0%, respectively, at 1 year after disease presentation. The serum level of anti-GBM antibodies (increased by 20 U/mL; hazard ratio [HR], 1.16; p = 0.009) and the presentation of positive antineutrophil cytoplasmic antibodies (ANCA) (HR, 2.18; p = 0.028) were independent predictors for patient death. The serum creatinine at presentation (doubling from 1.5 mg/dL; HR, 2.07; p < 0.001) was an independent predictor for renal failure.The combination therapy of plasmapheresis plus corticosteroids and cyclophosphamide had an overall beneficial effect on both patient survival (HR for patient mortality, 0.31; p = 0.001) and renal survival (HR for renal failure, 0.60; p = 0.032), particularly patient survival for those with Goodpasture syndrome (HR for patient mortality, 0.29; p = 0.004) and renal survival for those with anti-GBM nephritis with initial serum creatinine over 6.8 mg/dL (HR for renal failure, 0.52; p = 0.014). The treatment with corticosteroids plus cyclophosphamide was found not to improve the renal outcome of disease (p = 0.73).In conclusion, the combination therapy was preferred for patients with anti-GBM disease, especially those with pulmonary hemorrhage or severe renal damage. Early diagnosis was crucial to improving outcomes.Abbreviations: ANCA = antineutrophil cytoplasmic antibodies, CI = confidence interval, ELISA = enzyme-linked immunosorbent assay, ESRD = end-stage renal disease, GBM = glomerular basement membrane, HR = hazard ratio.

Anti-glomerular basement membrane autoantibodies against different target antigens are associated with disease severity

Anti-glomerular basement membrane (GBM) autoantibodies are pathogenic in the development of anti-GBM disease. The main target antigen is the non-collagenous 1 domain (NC1) of collagen alpha3(IV); however, most antibodies can recognize the NC1 of collagens alpha1, alpha2, alpha4 and alpha5(IV). In this study, we analyzed the target antigens of anti-GBM autoantibodies to determine their relationship to the severity of renal damage. Natural anti-GBM autoantibodies were purified from 10 healthy individuals and from 57 patients with anti-GBM disease who were divided into groups based on the degree of renal damage defined by their serum creatinine at the time of diagnosis. We found that the sera of all 57 patients recognized alpha3(IV)NC1, while 23, 20, 28, and 48 patients also recognized the NC1 of collagens alpha1, alpha2, alpha4, and alpha5(IV), respectively. Natural anti-GBM autoantibodies recognized the NC1 of collagens alpha3 and alpha4(IV). The sera of 7 patients with the lowest level of renal damage mainly recognized the NC1 of collagens alpha3 and alpha5(IV). In the 20 patients with moderate and the 30 with severe renal damage, all five target antigens could be detected and most sera recognized three to five different alpha chains simultaneously. Regression analysis showed that only the level of autoantibodies against the NC1 of collagen alpha3(IV) was a significant independent risk factor for higher serum creatinine on diagnosis. Our study shows that autoantibodies to the NC1 of collagen alpha3(IV) were crucial in causing renal damage. Inter- and intra-molecular epitope spreading can occur during the development of human anti-GBM disease.

Clinical Features and Outcomes of Anti–Glomerular Basement Membrane Disease in Older Patients

BACKGROUND Anti-glomerular basement membrane (GBM) disease is being recognized increasingly in older patients. Disease presentation and outcomes of these patients are unclear. STUDY DESIGN Case series. SETTING & PARTICIPANTS 221 consecutive Chinese patients with anti-GBM disease diagnosed in 1998-2008 in our tertiary referral center. Anti-GBM disease was defined as positive anti-GBM antibodies in circulation and/or linear immunoglobulin G deposition along the GBM on kidney biopsy. PREDICTOR Older age, defined as 65 years or older, and antineutrophil cytoplasmic antibody, detected using immunofluorescence and enzyme-linked immunosorbent assay, at presentation. OUTCOMES Clinical features, kidney pathologic characteristics, end-stage renal disease (ESRD), and mortality. Multivariate Cox proportional hazard models were used to assess the contribution of age, sex, clinical measures, and treatments to ESRD and mortality. RESULTS 50 of 221 (22.6%) patients were 65 years or older. Older patients had a male predominance (male/female ratio, 1.9:1). They had a higher proportion of positive antineutrophil cytoplasmic antibody results (46.0% vs 14.6%; P < 0.001), lower prevalence of hemoptysis (26.0% vs 46.2%; P = 0.01), lower urine protein excretion (1.4 ± 1.0 vs 3.9 ± 3.3 g/d; P = 0.001), and higher estimated glomerular filtration rate (eGFR) at presentation (8.4 vs 5.1 mL/min/1.73 m(2); P = 0.007) compared with younger patients. During follow-up, 30 of 37 (81.1%) and 21 of 37 (56.8%) patients developed ESRD and died in the older group compared with 115 of 139 (82.7%) and 35 of 139 (25.2%) in the younger group (P = 0.1 and P = 0.001, respectively). For older patients, multivariate Cox regression analysis showed that higher initial eGFR was an independent predictor for both ESRD (HR, 0.86; 95% CI, 0.78-0.96; P = 0.005) and death (HR, 0.79; 95% CI, 0.66-0.94; P = 0.008). LIMITATIONS Not all patients underwent kidney biopsy, especially those with very old age or ESRD at presentation. CONCLUSIONS Older patients with anti-GBM disease had milder kidney damage and less pulmonary involvement. Outcomes were predicted by initial eGFR. Thus, early diagnosis was crucial to improve outcomes.

Antibodies against Linear Epitopes on the Goodpasture Autoantigen and Kidney Injury

BACKGROUND AND OBJECTIVES Linear epitopes on the Goodpasture autoantigen involved in human anti-glomerular basement membrane (GBM) disease are not fully defined. This study investigated the linear epitopes recognized by circulating antibodies in anti-GBM patients, aiming to identify the potential nephrogenic linear epitopes and their clinical significance. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Sixty-eight patients with anti-GBM disease were enrolled. Twenty-four overlapping linear peptides were synthesized across the whole sequence of the human Goodpasture autoantigen. ELISA detected circulating antibodies against linear epitopes. Their associations with clinical features were further analyzed. RESULTS Antibodies against linear peptides were detected in sera from 55 patients (80.9%). Three major epitopes with high frequencies were identified: P14 (41%), P16 (36.8%), and P18 (57%). P14, a formerly defined T cell epitope, was a mutual B cell epitope. Antibodies against P14 were frequently detected in patients with positive antineutrophil cytoplasmic antibodies (39.3% versus 12.5%; P=0.01). Patients with anti-P16 antibodies presented with higher serum creatinine on diagnosis (665.5±227.2 versus 443.7±296.8 μmol/L; P=0.001) and worse renal outcome during follow-up (hazard ratio, 2.10; 95% confidence interval, 1.10-3.90; P=0.02). The level of anti-P18 antibodies positively correlated with the percentage of crescents in glomeruli (r=0.54; P=0.008). Recognition of P22 was an independent predictor for patient death (hazard ratio, 3.02; 95% confidence interval, 1.20-7.57; P=0.02). CONCLUSIONS Antibodies against linear epitopes on the Goodpasture autoantigen could be detected in human anti-GBM disease and were associated with kidney injury. P14 was a mutual T and B cell epitope, implying its nephrogenic role in disease initiation.

The Alternative Pathway of Complement Activation May Be Involved in the Renal Damage of Human Anti-Glomerular Basement Membrane Disease

Linear deposition of IgG and complement 3 (C3) along glomerular basement membrane (GBM) is generally revealed in the kidneys of human anti-GBM disease. Our recent studies demonstrated the pathogenic role of complement activation in renal damage of this disease. However, the pathways of complement activation were still paradoxical. In this study, renal biopsy tissues from 10 patients with anti-GBM disease were used to investigate the pathways of complement activation by detecting the deposition of various complement components, including C1q, factor B, factor P (properdin), mannose-binding lectin (MBL), C3d, C4d and C5b-9, using immunohistochemistry and immunofluorescence. We found that C1q, factor B, properdin, C3d, C4d and C5b-9 were detected in all the glomeruli of our patients, along GBM with a linear and/or granular staining pattern. Furthermore, C1q, factor B and properdin co-localized well with C5b-9. The properdin also co-localized well with C3d. However, the deposition of MBL was diffusive in mesangium, GBM, Bowmans capsule and within crescents and was not co-localized with C5b-9 but partially co-localized with C4d. The intensity of factor B deposition (3.3 vs. 1.2, P<0.001) and C5b-9 deposition (3.2 vs. 1.6, P<0.001) was significantly stronger in the glomeruli with crescent formation, compared with the glomeruli without crescents. The complement system is overall activated via both the alternative pathway and classical pathway in the kidneys of human anti-GBM disease. The alternative pathway might play an important role in complement activation induced renal damage.

Association of Epitope Spreading of Antiglomerular Basement Membrane Antibodies and Kidney Injury

BACKGROUND AND OBJECTIVES Antiglomerular basement membrane autoantibodies are pathogenic in antiglomerular basement membrane disease with two major epitopes, E(A) and E(B), on α3 chain of type IV collagen. This study investigated the epitope spectrum of antiglomerular basement membrane autoantibodies, aiming to identify the association between epitope specificity and kidney injury. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS All 108 patients with antiglomerular basement membrane disease and complete clinical data were divided into three groups according to renal dysfunction: mild group (n=20) with serum creatitine≤1.5 mg/dl; moderate group (n=22) with serum creatinine=1.5-6.8 mg/dl; severe group (n=66) with serum creatitine≥6.8 mg/dl. Epitope spectrums of antibodies were determined by ELISA, and their associations with kidney damage were analyzed. Sequential serum samples in 40 patients were examined during disease courses. RESULTS E(A) and E(B) were recognized in 79.6% and 72.2% of patients, respectively. E(A) and E(B) reactions were the lowest in the mild group and higher in the moderate group (E(A): 35.0% versus 81.8%, P=0.002; E(B): 15.0% versus 68.2%, P=0.001). They were the highest in the severe group (E(A): 92.4%, P=0.31; E(B): 90.9%, P=0.02). Close association was observed between renal injury and E(A) and E(B) reactions. Multivariate Cox regression analysis showed that E(B) reaction was an independent risk factor for renal failure (hazard ratio=6.91, P=0.02). The recognition for non-E(AB) remained low among groups. No augmentation of epitope spectrum was shown in serial serum samples. CONCLUSIONS Intramolecular epitope spreading might occur before the onset of human antiglomerular basement membrane disease. The autoimmunity to E(A) and E(B), especially E(B), was crucial for kidney dysfunction.

Circulating anti-glomerular basement membrane autoantibodies against α3(IV)NC1 undetectable by commercially available enzyme-linked immunosorbent assays.

Aim:  Cases with anti‐glomerular basement membrane (GBM) disease have been reported with linear deposit of immunoglobulin G (IgG) along GBM, but have undetectable anti‐GBM antibodies in circulation by enzyme linked immunosorbent assays (ELISA). We speculated that the structure of the antigens recognized by these antibodies may contribute to the negative results of ELISA.

The clinical and immunological features of patients with combined anti-glomerular basement membrane disease and membranous nephropathy

The association of anti-glomerular basement membrane (GBM) disease, also known as Goodpastures disease, with membranous nephropathy (MN) has been well documented. However, little is known about the clinical and immunological features of patients with such a combination. This study was designed to investigate the clinical and immunological features of anti-GBM patients with MN and to provide insight into the pathogenesis of this rare entity. Eight patients with combined anti-GBM disease and MN were found to have significantly lower levels of serum creatinine, a significantly lower proportion of oliguria/anuria, and significantly better renal outcomes compared with 30 patients with classical anti-GBM disease. Antibody levels against the EB conformational epitope of anti-α3(IV)NC1 were significantly lower in these patients, as was their levels of anti-α3(IV)NC1 immunoglobulin G1 (IgG1) and IgG3. Serum antibodies against the M-type phospholipase A2 receptor were undetectable in anti-GBM patients with MN but presented in 13 of the 20 patients with primary MN. Thus, patients with combined anti-GBM disease and MN have distinct clinical features and a different immunological profile of MN.

Influence of variable domain glycosylation on anti-neutrophil cytoplasmic autoantibodies and anti-glomerular basement membrane autoantibodies

BackgroundThe pathophysiological significance of variable region glycosylation of autoantibodies is still unclear. In the current study, the influence of the variable region N-linked oligosaccharides on the reactivity of three autoantibody specificities was investigated with Sambucus nigra agglutinin (SNA), which mainly binds to oligosaccharides with terminal α2, 6-linked sialic acid on the variable region of IgG.MethodsTwenty-seven patients with serum positive anti-neutrophil cytoplasmic autoantibodies (ANCA) against myeploperoxidase (MPO) or proteinase 3 (PR3), or autoantibodies against glomerular basement membrane (GBM) were included. Total IgG was isolated and separated into non-SNA-binding and SNA-binding fractions with SNA affinity chromatography. Antigen-specific IgG was purified by immunoaffinity chromatography.ResultsAt the same concentration of IgG, the antigen binding level of non-SNA-binding IgG was significantly lower than that of SNA-binding IgG for MPO-ANCA (absorbance value at 405 nm, 0.572 ± 0.590 vs. 0.962 ± 0.670, P < 0.001) and for PR3-ANCA (0.362 ± 0.530 vs. 0.560 ± 0.531, P = 0.003). The antigen binding level of non-SNA-binding IgG was significantly higher than that of SNA-binding IgG for anti-GBM antibodies (1.301 ± 0.594 vs. 1.172 ± 0.583, P = 0.044). The level of variable region glycosylation of total IgG was significantly lower than that of affinity-purified MPO-ANCA (1.021 ± 0.201 vs. 1.434 ± 0.134, P = 0.004). The level of variable region glycosylation of total IgG was significantly higher than that of affinity-purified anti-GBM antibodies (1.034 ± 0.340 vs. 0.734 ± 0.333, P = 0.007). The SNA-binding fraction of MPO-ANCA-containing IgG and PR3-ANCA-containing IgG induced higher levels of neutrophil oxygen radical production than the corresponding non-SNA-binding fractions (P < 0.001 and P = 0.043, respectively). The level of variable region glycosylation of affinity-purified MPO-ANCA was higher in active AAV than the same patients in remission (P = 0.001).ConclusionCharacteristics of variable region glycosylation of ANCA and anti-GBM antibodies were different from that of total IgG, which might influence the antigen-binding ability of these antibodies. Variable region glycosylation of ANCA might influence the effect of ANCA-induced neutrophils respiratory burst.

T cell infiltration is associated with kidney injury in patients with anti-glomerular basement membrane disease

Cell-mediated autoimmunity, particularly that involving autoreactive T cells, participates in mediating anti-glomerular basement membrane (GBM) disease. However, direct kidney injury mediated by renal infiltrated T cells has not been clearly elucidated in humans. The T cell profile (CD3, CD4, CD8, IL-17, and foxp3) and macrophage (CD68) were examined by immunohistochemistry on renal biopsy tissues from 13 patients with anti-GBM disease. The correlation between cell infiltration and clinical data was also analyzed. We found that the distribution of T cell infiltration was predominant in the peri-glomerular and interstitial areas. CD3+ T cell infiltratrion around the glomeruli with cellular crescent formations was significantly higher than that around the glomeruli with mild mesangial proliferation. CD8+ T cells significantly accumulated around the glomeruli with cellular crescents without IgG deposits compared to those with IgG deposits. The prevalence of infiltrating CD8+ T cells was correlated with the percentage of ruptured Bowman’s capsules. In conclusion, cellular immunity may play a crucial role in the inflammatory kidney injury in anti-GBM patients. The periglomerular infiltration of T cells, especially CD8+ T cells, may participate in the pathogenic mechanism of glomerular damage.