Ming-hui Zhao

Inclusion of renal vascular lesions in the 2003 ISN/RPS system for classifying lupus nephritis improves renal outcome predictions

The 2003 International Society of Nephrology/Renal Pathology Society (ISN/RPS) pathological classification system of lupus nephritis specified the importance of vascular damage and indicated this should be included in the diagnostic summary. Few pathological studies of lupus nephritis, however, focus on the patterns of renal vascular involvement. Here we assessed renal vascular lesions in lupus nephritis based on the 2003 ISN/RPS classification system and evaluated their association with clinical and pathological data in a large cohort from a single center in China. Among 341 patients with lupus nephritis, 279 were diagnosed with single or multiple renal vascular lesions that included 253 with vascular immune complex deposits, 82 with atherosclerosis, 60 with thrombotic microangiopathy, 13 with noninflammatory necrotizing vasculopathy, and 2 with true renal vasculitis. Patients with thrombotic microangiopathy had the poorest renal outcome. In multivariate Cox hazard analysis after inclusion of renal vascular lesions, the new chronicity index score became a significantly better independent risk factor for renal outcome (hazard ratio 2.32). Thus, renal vascular lesions are common in lupus nephritis and closely correlate with clinical disease activity and renal outcome. Inclusion of a detailed description of renal vascular lesions in the ISN/RPS classification of lupus nephritis may strengthen its predictive value for renal outcome.

Complement Activation Contributes to the Injury and Outcome of Kidney in Human Anti-glomerular Basement Membrane Disease

PurposeLinear or granular deposition of complement 3 (C3) along glomerular basement membrane (GBM) is generally revealed in kidneys of human anti-GBM disease. However, the mechanism of complement activation and its association with clinical features and outcomes are less clear.MethodsWe measured the plasma and urinary levels of complement components, C1q, mannose-binding lectin (MBL), factor B (Ba), C3, C3a, C4, C4a, C5, C5a and soluble C5b-9 (SC5b-9), using ELISA in 20 patients with renal biopsy proven anti-GBM disease.ResultsThe end product of complement activation, SC5b-9, was elevated both in plasma and urine. The levels of C3 and C4 were normal in plasma, while elevated in urine. The levels of C5a and SC5b-9 were increased in plasma from 15% and 30% patients respectively, while they were raised in urine from almost all patients (100% and 92%). The levels of plasma SC5b-9 and urinary C5a were positively correlated with the serum creatinine at presentation (ru2009=u20090.56, Pu2009=u20090.01; ru2009=u20090.68, Pu2009=u20090.02, respectively) and the percentage of crescents in glomeruli (ru2009=u20090.60, Pu2009=u20090.005; ru2009=u20090.75, Pu2009=u20090.005, respectively). The plasma level of SC5b-9 was further identified as the predictor for renal failure during follow up (HR, 1.46; 95% CI, 1.12-1.90; Pu2009=u20090.005).ConclusionComplement cascade goes to the end in human anti-GBM disease and resides mainly in kidney. It plays pathogenic role in renal injury, by the possible proinflammatory effect of C5a and/or cell lysis effect of C5b-9. C5a and C5b-9 may be useful in clinical monitoring and predicting.

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.

MHC Class II Risk Alleles and Amino Acid Residues in Idiopathic Membranous Nephropathy

Epitopes of phospholipase A2 receptor (PLA2R), the target antigen in idiopathic membranous nephropathy (iMN), must be presented by the HLA-encoded MHC class II molecules to stimulate autoantibody production. A genome-wide association study identified risk alleles at HLA and PLA2R loci, with the top variant rs2187668 within HLA-DQA1 showing a risk effect greater than that of the top variant rs4664308 within PLA2R1. How the HLA risk alleles affect epitope presentation by MHC class II molecules in iMN is unknown. Here, we genotyped 261 patients with iMN and 599 healthy controls at the HLA-DRB1, HLA-DQA1, HLA-DQB1, and HLA-DPB1 loci with four-digit resolution and extracted the encoded amino acid sequences from the IMGT/HLA database. We predicted T cell epitopes of PLA2R and constructed MHC-DR molecule-PLA2R peptide-T cell receptor structures using Modeler. We identified DRB1*1501 (odds ratio, 4.65; 95% confidence interval [95% CI], 3.39 to 6.41; P<0.001) and DRB1*0301 (odds ratio, 3.96; 95% CI, 2.61 to 6.05; P<0.001) as independent risk alleles for iMN and associated with circulating anti-PLA2R antibodies. Strong gene-gene interaction was noted between rs4664308(AA) and HLA-DRB1*1501/DRB1*0301. Amino acid positions 13 (P<0.001) and 71 (P<0.001) in the MHC-DRβ1 chain independently associated with iMN. Structural models showed that arginine13 and alanine71, encoded by DRB1*1501, and lysine71, encoded by DRB1*0301, facilitate interactions with T cell epitopes of PLA2R. In conclusion, we identified two risk alleles of HLA class II genes and three amino acid residues on positions 13 and 71 of the MHC-DRβ1 chain that may confer susceptibility to iMN by presenting T cell epitopes on PLA2R.

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.

Antibodies to α5 chain of collagen IV are pathogenic in Goodpasture's disease.

Autoantibody against glomerular basement membrane (GBM) plays a direct role in the initiation and development of Goodpastures (GP) disease. The principal autoantigen is the non-collagenous domain 1 (NC1) of α3 chain of collagen IV, with two immunodominant epitopes, EA-α3 and EB-α3. We recently demonstrated that antibodies targeting α5NC1 are bound to kidneys in GP patients, suggesting their pathogenic relevance. In the present study, we sought to assess the pathogenicity of the α5 autoantibody with clinical and animal studies. Herein, we present a special case of GP disease with circulating autoantibody reactive exclusively to the α5NC1 domain. This autoantibody reacted with conformational epitopes within GBM collagen IV hexamer and produced a linear IgG staining on frozen sections of human kidney. The antibody binds to the two regions within α5NC1 domain, EA and EB, and inhibition ELISA indicates that they are targeted by distinct sub-populations of autoantibodies. Sequence analysis highlights five residues that determine specificity of antibody targeting EA and EB epitopes of α5NC1 over homologous regions in α3NC1. Furthermore, immunization with recombinant α5NC1 domain induced crescentic glomerulonephritis and alveolar hemorrhage in Wistar-Kyoto rats. Thus, patient data and animal studies together reveal the pathogenicity of α5 antibodies. Given previously documented cases of GP disease with antibodies selectively targeting α3NC1 domain, our data presents a conundrum of why α3-specific antibodies developing in majority of GP patients, with α5-specific antibodies emerged in isolated cases, the answer for which is critical for understanding of etiology and progression of the GP disease.

The susceptible HLA class II alleles and their presenting epitope(s) in Goodpasture's disease

Goodpastures disease is closely associated with HLA, particularly DRB1*1501. Other susceptible or protective HLA alleles are not clearly elucidated. The presentation models of epitopes by susceptible HLA alleles are also unclear. We genotyped 140 Chinese patients and 599 controls for four‐digit HLA II genes, and extracted the encoding sequences from the IMGT/HLA database. T‐cell epitopes of α3(IV)NC1 were predicted and the structures of DR molecule‐peptide—T‐cell receptor were constructed. We confirmed DRB1*1501 (OR = 4·6, P = 5·7 × 10−28) to be a risk allele for Goodpastures disease. Arginine at position 13 (ARG13) (OR = 4·0, P = 1·0 × 10−17) and proline at position 11 (PRO11) (OR = 4·0, P = 2·0 × 10−17) on DRβ1, encoded by DRB1*1501, were associated with disease susceptibility. α134–148 (HGWISLWKGFSFIMF) was predicted as a T‐cell epitope presented by DRB1*1501. Isoleucine137, tryptophan140, glycine142, phenylalanine143 and phenylalanine145, were presented in peptide‐binding pockets 1, 4, 6, 7 and 9 of DR2b, respectively. ARG13 in pocket 4 interacts with tryptophan140 and forms a hydrogen bond. In conclusion, we propose a mechanism for DRB1*1501 susceptibility for Goodpastures disease through encoding ARG13 and PRO11 on MHC‐DRβ1 chain and presenting T‐cell epitope, α134–148, with five critical residues.

T cell responses to peptides of Goodpasture autoantigen in patients with anti‐glomerular basement membrane disease

Cell‐mediated autoimmunity, especially autoreactive T cells, is crucial in the initiation of anti‐glomerular membrane (GBM) disease. Epitopes for T cells on Goodpasture autoantigen are not fully defined. This study investigated T cell epitopes in anti‐GBM patients, aiming to identify the epitopes and their clinical significance.

Big data and medical research in China

Luxia Zhang and colleagues discuss the development of big data in Chinese healthcare and the opportunities for its use in medical research

Serum A08 C1q antibodies are associated with disease activity and prognosis in Chinese patients with lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by overproduction of numerous autoantibodies. Many studies have sought to identify such biomarkers to distinguish patients with active lupus nephritis from SLE patients without renal involvement. Because antibodies to complement C1q appear to be prevalent in patients with active lupus nephritis, we analyzed the frequency of antigenic epitopes of C1q and their clinical significance in a large multicenter study of Chinese patients. The lupus cohort consisted of 210 patients with active lupus nephritis as a discovery cohort, 130 active patients as a validation cohort along with 130 SLE patients without clinical renal involvement, and 100 healthy controls. Serum antibodies to intact C1q, the collagen-like region, the globular head region, and the new linear A08 epitope to C1q were screened by specific ELISA. The frequency of antibodies to intact C1q, the C1q-collagen-like region, and the A08 antibodies in the discovery cohort were significantly higher than that in patients without renal involvement or healthy controls. Antibodies to the globular head region were not prevalent enough for further study. The results were confirmed in the validation cohort. The area under the curve for anti-A08 antibodies was significantly greater than those for both the intact and collagen-like region antibodies to discriminate between active lupus nephritis and active SLE without clinical renal involvement. The A08 antibodies were all negative at remission. The serum A08 antibody level correlated better with disease relapse than that of antibodies to either the intact or the collagen-like region, significantly predicting renal prognosis. Thus, serum levels of A08 C1q antibodies are closely associated with disease activity and prognosis in lupus nephritis.