The HLA-DRB1*1501 allele is prevalent among Japanese patients with anti-glomerular basement membrane antibody-mediated disease

The Association of Class I and II Human Leukocyte Antigen Serotypes With End-Stage Kidney Disease Due to Membranoproliferative Glomerulonephritis and Dense Deposit Disease

RATIONALE & OBJECTIVE

Membranoproliferative glomerulonephritis (MPGN), encompassing several distinct diseases, is a rare but significant cause of kidney failure in the United States. The potential etiologies of MPGN are unclear, but prior studies have suggested dysregulation of the alternative complement pathway and, recently, autoimmunity as potential mechanisms driving MPGN pathogenesis. In this study, we examined HLA associations with end-stage kidney disease (ESKD) due to MPGN and dense deposit disease (DDD) in a large racially and ethnically diverse US-based cohort.

STUDY DESIGN

Case-control study.

SETTING & PARTICIPANTS

Using US Renal Data System (USRDS) and United Network for Organ Sharing (UNOS) data, we identified 3,424 patients with kidney failure due to MPGN and 263 due to DDD. We matched patients to kidney donor controls on designated race and ethnicity in a 1:15 ratio.

EXPOSURE

58 class I and II HLA serotypes.

OUTCOME

Case-control status.

ANALYTICAL APPROACH

For each disease cohort, univariable and multivariable logistic regression analyses were used to investigate associations between the disease and 58 HLA serotypes. In subgroup analyses, we investigated HLA associations in White and Black patients. We also studied antiglomerular basement membrane (anti-GBM) nephritis as a positive-control outcome. We applied a Bonferroni correction to account for multiple comparisons.

RESULTS

Eighteen serotypes were significantly associated with the odds of having MPGN in univariable analyses, with DR17 having the strongest association (odds ratio [OR], 1.55 [95% CI, 1.44-1.68], P=4.33e-28). No significant associations were found between any HLA serotype and DDD. Designated race-specific analyses showed comparable findings. We recapitulated known HLA associations in anti-GBM nephritis.

LIMITATIONS

Reliance on HLA serotypes (rather than genotype), lack of biopsy-confirmed diagnoses.

CONCLUSIONS

HLA-DR17 is associated with ESKD due to MPGN in a racially and ethnically diverse cohort. The strength of association was similar in White and Black patients, suggesting a role in the pathogenesis of MPGN. No HLA associations were observed in patients with DDD.

PLAIN-LANGUAGE SUMMARY

Prior studies have suggested dysregulation of the alternative complement pathway as a potential etiology of membranoproliferative glomerulonephritis (MPGN), but recent evidence from a British White population has implicated an autoimmune mechanism in MPGN pathogenesis. We investigated HLA associations between MPGN and dense deposit disease (DDD) in a large racially and ethnically diverse cohort of patients. We found that HLA-DR17 is associated with end-stage kidney disease (ESKD) due to MPGN in both White and Black patients. By contrast, no significant HLA associations with ESKD due to DDD were identified. These results suggest a role for autoimmunity in some cases of MPGN and highlight differences in the disease etiology of MPGN compared with DDD.

Rituximab for the treatment of refractory anti-glomerular basement membrane disease

BACKGROUND

Anti-glomerular basement membrane (anti-GBM) disease is a rare but severe autoantibody-mediated immune disorder. The typical clinical presentation includes rapidly progressive glomerulonephritis and often concurrent pulmonary hemorrhage. The present study is aimed to investigate the therapeutic effects of rituximab either used alone or with other immunosuppressants.

METHODS

Eight patients diagnosed with anti-GBM disease and treated with rituximab from 2014 to 2020 were retrospectively reviewed.

RESULTS

Eight patients included 5 males and 3 females with a median age of 58.5 years. They all presented severe kidney injuries and 1 patient had lung hemorrhage. At diagnosis, the median of serum creatinine was 246 µmol/L (ranging from 91 to 850 µmol/L), with 3 patients requiring dialysis. All of them received corticosteroids and plasmapheresis. Rituximab was given as either standard four weekly doses or one pulse ranging from 100 to 600 mg. After a median follow-up of 34.5 months, kidney function was partially recovered or stabilized in 5/8 (62.5%) patients, free of dialysis. Anti-GBM antibodies remained undetected in all patients during follow-up. No severe adverse effect associated with rituximab was observed.

CONCLUSION

Rituximab may be an alternative therapy in the treatment of patient with severe or refractory anti-GBM disease.

A case of anti-GBM nephritis following centipede bites and COVID-19 vaccination

A case of newly developed anti-glomerular basement membrane (GBM) glomerulonephritis (GN) following centipede bites and COVID-19 vaccination is presented. A 70-year-old woman presented for investigation of mild fever, generalized fatigue, and macroscopic hematuria with no past history of renal disease. One year earlier, she had been bitten by a centipede. Based on the governmental policy, she was given the first COVID-19 vaccination, and the second injection was planned 3 weeks later. Accidentally, she was again bitten by a centipede, and the injured site had swollen severely. Based on a physician's judgment, the interval between vaccinations was extended to 8 weeks. One week after the second vaccination, macroscopic hematuria occurred suddenly, coincident with mild fever. Her serum anti-GBM titer was above the upper limit. There was no pulmonary involvement. Renal pathology showed anti-GBM GN, and she was treated with corticosteroid pulse therapy followed by sequential plasmapheresis. She had advanced renal dysfunction, but was independent of dialysis therapy during the one month of the remission induction therapy phase, and she is being treated with immunosuppressant therapy. Both vaccination and animal bites skew towards Th1 immunity, a key mechanism involved in the development of necrotizing GN evoked by anti-GBM antibody. Though there is no direct evidence for causality linking centipede bites, vaccination, and anti-GBM GN, the risk of anti-GBM GN appears to be increased by excessively induced Th1 immunity.

Acquired aplastic anemia complicated with anti-glomerular basement membrane disease successfully treated with immunosuppressive therapy: a case report

BACKGROUND

Aplastic anemia (AA) is a rare but fatal disorder characterized by pancytopenia due to bone marrow hypoplasia. Anti-glomerular basement membrane disease (anti-GBM disease) is an immune complex small-vessel vasculitis that presents as rapidly progressive glomerulonephritis and/or pulmonary hemorrhage. Although both involve autoreactive T cells that are partially triggered by human leukocyte antigen (HLA)-DR15, there have been no reports of their co-existence and the treatment strategy is not well understood.

CASE PRESENTATION

A 67-year-old woman presented with fever, malaise, and acute kidney injury with proteinuria and hematuria requiring hemodialysis. She was diagnosed with anti-GBM antibody disease based on high serum anti-GBM antibody titer and crescentic glomerulonephritis on a renal biopsy. Pulse administration of methylprednisolone (MP), oral prednisolone (PSL), and plasmapheresis were performed. Only 2 weeks after the diagnosis of anti-GBM disease, the patient developed pancytopenia requiring frequent blood transfusions. The blood cell count did not recover even 1 month after discontinuing the drugs that could cause pancytopenia. Bone marrow examination showed hypocellularity without abnormal infiltrates or fibrosis, which led to the diagnosis of severe acquired AA. Further HLA phenotyping revealed that she had HLA-DR15. Increased dose of PSL with the secondary MP pulse and the addition of cyclosporine improved pancytopenia. Although she remained dialysis-dependent, anti-GBM disease and pancytopenia did not recur for more than 2 years.

CONCLUSIONS

We report the first case of acquired AA complicated with anti-GBM disease in an elderly woman with HLA-DR15, which was successfully treated with immunosuppressive therapy (IST). This report is valuable not only because it shows they may co-occur, but also because it provides a therapeutic option for this complex condition. It was also suggested that pancytopenia in patients with anti-GBM disease recalls serious hematologic diseases including AA that require immediate treatment based on bone marrow examination.

ANCA and anti-glomerular basement membrane double-positive patients: A systematic review of the literature

INTRODUCTION

Double-positive patients (DPP) exhibiting anti-glomerular basement membrane (GBM) and anti-neutrophil cytoplasmic antibodies (ANCAs) belong to an entity that is newly and poorly described, mainly in short series. We aimed to better characterize the epidemiological features, clinical presentation and therapeutic outcomes of these patients through a systematic review.

METHODS

We performed a systematic review of English-, German-, Spanish- and French-written publications from February 1987 to March 2020 reporting cases of DPP using the following databases: PubMed, Scielo, ScienceDirect, Google Scholar, The Cochrane Library, Open Grey, The Grey Literature Report, Clinicaltrials.gov and International Clinical Trial Registry Platform of the World Health Organization.

RESULTS

In total, 538 DPP were identified from 90 articles. Their clinical presentations were often severe, and the majority exhibited acute kidney failure (91.8%) with a median initial serum creatinine level of 873 μmol/L; 50.7% had alveolar haemorrhage. Other manifestations were present in 30.3% of DPP, mainly ear, nose, throat and articular manifestations. ANCAs were predominantly directed against MPO (n = 377/523; 72.1%) compared to PR3 (n = 107/523; 20.5%), with rare cases of triple positivity (n = 15/538; 2.9%). Although most patients received initial immunosuppressive therapy (n = 285/317; 89.9%), the one-year overall, renal and relapse-free survival rates were 64.8%, 38.7% and 71.1%, respectively.

CONCLUSION

DPP are associated with the characteristics of two eponymous vasculitis types, responsible for a poor overall and renal prognosis. Thus, simultaneous testing of both antibodies and systematic renal biopsy should be recommended in every patient with rapidly progressive glomerulonephritis to recognize this difficult-to-treat and rare disease.

Anti-glomerular Basement Membrane Glomerulonephritis During the First Trimester of Pregnancy

A 28-year-old woman was admitted during the eighth week of her pregnancy because her clinical course was consistent with rapid progressive glomerulonephritis (RPGN). Anti-glomerular basement membrane antibody (anti-GBM Ab) and myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) were positive, and the anti-GBM Ab titer being extremely high. She was treated with hemodialysis, plasma exchange and prednisolone. She survived the illness; however, neither the fetus nor her kidney function could be rescued. She had human leukocyte antigen (HLA)-DRB1*1502:01, which differs from the DRB1*1501 associated with anti-GBM GN. When patients have particular symptoms, we should check the urine and serum creatinine to exclude RPGN, even in cases of pregnancy.

Common Denominators in the Immunobiology of IgG4 Autoimmune Diseases: What Do Glomerulonephritis, Pemphigus Vulgaris, Myasthenia Gravis, Thrombotic Thrombocytopenic Purpura and Autoimmune Encephalitis Have in Common?

IgG4 autoimmune diseases (IgG4-AID) are an emerging group of autoimmune diseases that are caused by pathogenic autoantibodies of the IgG4 subclass. It has only recently been appreciated, that members of this group share relevant immunobiological and therapeutic aspects even though different antigens, tissues and organs are affected: glomerulonephritis (kidney), pemphigus vulgaris (skin), thrombotic thrombocytopenic purpura (hematologic system) muscle-specific kinase (MuSK) in myasthenia gravis (peripheral nervous system) and autoimmune encephalitis (central nervous system) to give some examples. In all these diseases, patients’ IgG4 subclass autoantibodies block protein-protein interactions instead of causing complement mediated tissue injury, patients respond favorably to rituximab and share a genetic predisposition: at least five HLA class II genes have been reported in individual studies to be associated with several different IgG4-AID. This suggests a role for the HLA class II region and specifically the DRβ1 chain for aberrant priming of autoreactive T-cells toward a chronic immune response skewed toward the production of IgG4 subclass autoantibodies. The aim of this review is to provide an update on findings arguing for a common pathogenic mechanism in IgG4-AID in general and to provide hypotheses about the role of distinct HLA haplotypes, T-cells and cytokines in IgG4-AID.

Clinical and immunologic characteristics of Japanese patients with anti-glomerular basement membrane disease: case reports and literature review

Background

Clinical studies of anti-glomerular basement membrane (GBM) disease were limited because of the low incidence. We aimed to report the characteristics, treatments, and outcomes of patients with anti-GBM disease at a tertiary reference medical center in Japan and review the literature of mortality in patients with anti-GBM disease.

Case presentation

Case 1 was a 72-year-old Japanese man that was referred with worsening of the serum creatinine (from 1.1 to 27.3 mg/dL). Anti-GBM disease was confirmed by renal biopsy, and treatments with oral prednisolone and plasmapheresis were initiated. Although his anti-GBM antibody decreased (from 476 to 18 units/mL) after the treatments, the patient died from lung abscess. Case 2 was a 32-year-old Japanese man that presented with fever and macroscopic hematuria. At presentation, his serum creatinine was 4.2 mg/dL, and anti-GBM antibody was 265 units/mL. Renal biopsy confirmed the diagnosis of anti-GBM disease, and intensive treatments with plasmapheresis and methyl prednisolone were started, followed by oral prednisolone. Living-donor kidney transplantation was performed because his anti-GBM antibody had remained undetectable for 1 year after diagnosis. In the main text, clinicopathological characteristics of 12 patients with anti-GBM disease at our institution were summarized.

Conclusions

We found that the 1-year survival rate of patients with anti-GBM disease was 88% in our cohort, which was comparable to previous studies. Multicenter, nationwide studies are expected to evaluate prognosis of Japanese patients with this rare entity.

Anti-glomerular Basement Membrane Disease: What Have We Learned?

Since the first clinicopathologic description by Ernest Goodpasture of a patient whom he considered to have died of influenza in 1919, substantial progress has been made in our knowledge of anti-glomerular basement membrane disease. This has led to a significant decrease in the morbidity and mortality associated with this disease. In this paper, we aim to review the literature that has enhanced our understanding of classic anti-glomerular basement membrane disease and its clinic-pathologic variants in the key areas of immunopathogenesis and histopathology. We also summarize varied clinical presentations and therapeutic strategies.

Anti-glomerular basement membrane disease: an update on subgroups, pathogenesis and therapies

Most patients with anti-glomerular basement membrane (anti-GBM) disease present with rapidly progressive glomerulonephritis with or without pulmonary haemorrhage; however, there are several variants and vigilance is necessary to make a correct diagnosis. Such variants include overlap with anti-neutrophil cytoplasm antibodies-associated vasculitis and membranous nephropathy as well as anti-GBM occurring de novo after renal transplantation. Moreover, patients can present with isolated pulmonary haemorrhage as well as with negative tests for circulating anti-GBM. Virtually all patients with anti-GBM disease have autoantibodies that react with two discrete epitopes on the α3 chain of type IV collagen. Recent evidence suggests that healthy persons have low-affinity natural antibodies reacting with the same epitopes, but most people are protected from developing disease-causing high-affinity autoantibodies by human leukocyte antigen-dependent regulatory T-cells (Tregs). The α3 chain-derived peptides presented by the HLA-DR15 antigen lack the ability to promote the development of such Tregs. The detection of anti-GBM in circulation using the rapid assay test has led to early diagnosis and improved prognosis. However, our present tools to curb the inflammation and to eliminate the assaulting antibodies are insufficient. Only about one-third of all patients survive with functioning native kidneys. More effective therapies need to be developed; agents that inhibit neutrophil recruitment, deplete B cells and cleave immunoglobulin G (IgG) in vivo may become new weapons in the arsenal to combat anti-GBM disease.

A single center study of protective and susceptible HLA alleles and haplotypes with end-stage renal disease in China

Chronic kidney disease (CKD) is becoming a global public health problem and usually cause End-Stage Renal Disease (ESRD) in the end of progression. To analyze the associations of HLA-A, -B, -C, -DRB1 and -DQB1 alleles at high resolution with ESRD in Jiangsu province of China, a total of 499 unrelated patients with ESRD from the First Affiliated Hospital with Nanjing Medical University and 1584 healthy controls from Jiangsu Branch of Chinese Marrow Donor Program (CMDP) were genotyped at HLA-A, -B, -C, -DRB1 and -DQB1 loci. Statistical analysis was applied to compare the differences of HLA allele frequencies between patients with ESRD and healthy controls. As results, no protective allele at A locus was found and the susceptible alleles were A*11:01 and A*31:01. At B locus, B*15:01, B*55:02 and B*39:05 emerged as susceptible alleles, whereas no protective allele was found. At C locus, C*06:02 and C*07:01 emerged as protective alleles and no susceptible allele was found. At DRB1 locus, six alleles including DRB1*03:01, DRB1*04:03, DRB1*04:04, DRB1*04:05, DRB1*11:01 and DRB1*12:02 emerged as susceptible alleles, while DRB1*15:01 emerged as a protective allele. At DQB1 locus, DQB1*02:01, DQB1*03:01, DQB1*03:02 and DQB1*04:01 emerged as susceptible alleles, while DQB1*06:02 and DQB1*06:09 emerged as protective alleles. Haplotype A*11:01-C*03:03-B*15:01-DRB1*11:01-DQB1*03:01 containing four susceptible alleles was regarded as the most susceptible haplotype. The susceptible alleles and haplotypes might be used as some important risk classification markers. Besides, in the consanguineous renal transplantation, it would be very beneficial for the long-term survival of renal transplant patients to avoid the susceptible alleles and haplotypes in selecting optimal donors.

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

AIM

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.

METHODS

Peripheral blood mononuclear cells (PBMC) were collected from 13 patients with anti-GBM disease. Twenty-four overlapping linear peptides were synthesized covering the whole sequence of human α3(IV)NC1. PBMC response to each peptide was detected by proliferation assay. Their associations with clinical features were further analyzed.

RESULTS

Peripheral blood mononuclear cells proliferative responses to linear peptides on α3(IV)NC1 could be detected in all patients. Five major epitopes were identified as stimulatory in over half of the patients: α3(IV)NC1_127-148 (P14) (69.2%), α3(IV)NC1_159-178 (77.8%), α3(IV)NC1_179-198 (55.6%), α3(IV)NC1_189-208 (P19) (75.0%) and α3(IV)NC1_141-154 (57.1%). P14 and P19 were highly recognized in patients comparing with healthy controls (69.2% vs. 0.0%, P = 0.011; 75.0% vs. 0.0%, P = 0.021, respectively).

CONCLUSION

T cell proliferation to linear epitopes was detected in human anti-GBM disease. α3_127-148 was a mutual T and B cell epitope, implying its initial role in epitope spreading process.

Management of adverse renal events related to alemtuzumab treatment in multiple sclerosis: a Belgian consensus

Alemtuzumab is a humanized monoclonal antibody indicated for the treatment of adult patients with relapsing–remitting multiple sclerosis with active disease. Multiple sclerosis (MS) patients treated with alemtuzumab are at increased risk for autoimmune adverse events (thyroid disorders, immune thrombocytopenia, and renal disease). The use of alemtuzumab has been associated with the development of renal immune-mediated adverse events in 0.3% of patients in clinical trials in MS, which generally occurred within 39 months of the last administration. Both anti-GBM disease and membranous nephropathy have been associated with the use of alemtuzumab. Early detection is necessary to allow for early diagnosis and prevent adverse renal and patient outcomes. Through the implementation of the risk minimization measures, patients can be diagnosed, and treated if needed, early allowing for generally favorable outcomes. This important goal can be reached through health care professional and patient education, careful analysis of the monthly lab tests, and close collaboration between the patient, neurologist, and the nephrologist. This article presents the consensus of Belgian MS specialists and nephrologists on the practicalities of diagnosis, management, and treatment of alemtuzumab-associated renal adverse events based on good clinical practice.

Goodpasture's autoimmune disease - A collagen IV disorder

Goodpasture's (GP) disease is an autoimmune disorder characterized by the deposition of pathogenic autoantibodies in basement membranes of kidney and lung eliciting rapidly progressive glomerulonephritis and pulmonary hemorrhage. The principal autoantigen is the α345 network of collagen IV, which expression is restricted to target tissues. Recent discoveries include a key role of chloride and bromide for network assembly, a novel posttranslational modification of the antigen, a sulfilimine bond that crosslinks the antigen, and the mechanistic role of HLA in genetic susceptibility and resistance to GP disease. These advances provide further insights into molecular mechanisms of initiation and progression of GP disease and serve as a basis for developing of novel diagnostic tools and therapies for treatment of Goodpasture's disease.

[Antiglomerular basement disease in children: Literature review and therapeutic options]

Antiglomerular basement membrane glomerulonephritis is a rare autoimmune disease characterized by rapidly progressive glomerulonephritis that may be associated with pulmonary hemorrhage (Goodpasture syndrome). The disease is caused by autoantibodies (classically IgGs) directed against the α3 subunit of type IV collagen. This is a rare disease in the adult population and extremely rare in children, with a reported cumulative annual incidence at 1/10⁶ people/year. Among scarce reported pediatric cases (n=31), most are girls (M/F sex ratio, 1:4), and the mean age at diagnoses is 9.2±4.6 years. A medical diagnosis is an emergency and is based on the identification of specific antibodies in the serum, and pathognomonic linear fixation of IgGs along the glomerular basement membrane. Without appropriate treatment, the disease is generally fulminant, and patient and kidney survival is poor. Indeed, glomerular function strongly correlates with histological lesions. The current guidelines recommend the use of plasma exchanges and immunosuppressive drugs. For the past few years, alternative therapeutics such as specific anti-B-cell antibodies (rituximab) or specific extrarenal cleansing such as immunoadsorption have been successfully used in adults. Immunoadsorptions (IAs) can remove pathogenic IgGs from the circulation and do not require plasma infusions, contrary to plasma exchanges. In this review, we discuss the key points of antiglomerular basement membrane glomerulonephritis diagnosis and conventional or alternative therapeutics.

Anti-Glomerular Basement Membrane Disease

Anti-glomerular basement membrane (anti-GBM) disease is a rare small vessel vasculitis that affects the capillary beds of the kidneys and lungs. It is an archetypic autoimmune disease, caused by the development of directly pathogenic autoantibodies targeting a well characterized autoantigen expressed in the basement membranes of these organs, although the inciting events that induce the autoimmune response are not fully understood. The recent confirmation of spatial and temporal clustering of cases suggests that environmental factors, including infection, may trigger disease in genetically susceptible individuals. The majority of patients develop widespread glomerular crescent formation, presenting with features of rapidly progressive GN, and 40%-60% will have concurrent alveolar hemorrhage. Treatment aims to rapidly remove pathogenic autoantibody, typically with the use of plasma exchange, along with steroids and cytotoxic therapy to prevent ongoing autoantibody production and tissue inflammation. Retrospective cohort studies suggest that when this combination of treatment is started early, the majority of patients will have good renal outcome, although presentation with oligoanuria, a high proportion of glomerular crescents, or kidney failure requiring dialysis augur badly for renal prognosis. Relapse and recurrent disease after kidney transplantation are both uncommon, although de novo anti-GBM disease after transplantation for Alport syndrome is a recognized phenomenon. Copresentation with other kidney diseases such as ANCA-associated vasculitis and membranous nephropathy seems to occur at a higher frequency than would be expected by chance alone, and in addition atypical presentations of anti-GBM disease are increasingly reported. These observations highlight the need for future work to further delineate the immunopathogenic mechanisms of anti-GBM disease, and how to better refine and improve treatments, particularly for patients presenting with adverse prognostic factors.

The critical amino acids of a nephritogenic epitope on human Goodpasture autoantigen for binding to HLA-DRB1*1501

BACKGROUND

Anti-GBM disease is caused by autoimmunity to Goodpasture antigen on α3(IV)NC1 and had strong associations with HLA-DRB1*1501. Previous studies identified α3_127-148 (P14: TDIPPCPHGWISLWKGFSFIMF) as a T cell epitope. The present study was aimed to investigate the binding capacity of P14 to HLA-DRB1*1501 and the critical amino acids for this binding.

METHODS

A line of EBV-transformed human B cells homozygous for HLA-DRB1*1501 was used to detect the binding capacity of peptides to HLA-DRB1*1501 using flow cytometry analysis. P14 was sequentially truncated into 8 peptides with 15 amino acids to identify the core binding motif. A set of alanine substituted peptides of P14-2 was then synthesized to identify its critical residues for binding to HLA-DRB1*1501. The structure of HLA-DR2b-Peptide-TCR complex was constructed by modeling to analyze the interaction of each amino acids of P14-2 with the HLA-DR2b molecule.

RESULTS

P14 could bind to HLA-DRB1*1501 expressed on B cell surface. The N-terminus of P14 was the core binding motif and the truncated peptide P14-2 (DIPPCPHGWISLWKG) _128-142 had the strongest binding capacity. After sequential amino acid substitution, we found the binding capacity of P14-2 was completely lost by the substitution of cysteine (C) ₁₃₂ and significantly decreased by the substitution of tryptophan (W) ₁₃₆, lysine (K) ₁₄₁, or glycine (G) ₁₄₂, but still at a high level. The modeling showed that (C) ₁₃₂ had a strong interaction with pocket 4 on the β chain of DR2b. Thus, C₁₃₂, W ₁₃₆, K₁₄₁, and G₁₄₂ were defined as the critical amino acid residues for the binding capacity of P14 to HLA-DRB1*1501.

CONCLUSION

We identified α3_128-142 (DIPPCPHGWISLWKG) as the core binding motif of P14 to HLA-DRB1*1501 molecule. And the critical amino acid residues for this binding were further defined as C₁₃₂, W ₁₃₆, K ₁₄₁, and G ₁₄₂.

Anti-glomerular basement membrane disease accompanied by systemic lupus erythematosus presenting central nervous system involvement

We report a case of rapidly progressive glomerulonephritis caused by anti-glomerular basement membrane (GBM) disease accompanied by systemic lupus erythematosus (SLE) presenting central nervous system involvement in a 32-year-old Japanese male. He was admitted to our hospital because of a 3-week history of fever and rapidly failing renal function requiring hemodialysis (HD). Laboratory tests showed anti-GBM antibody elevation with a value of 16,385 units/ml. On day 85, he had generalized tonic-clonic seizure. Brain magnetic resonance T2 Flair imaging showed multiple high intensity lesions in a broad area. We made a diagnosis of central nervous system involvement in SLE based on positivity for antinuclear and anti-DNA antibodies, hypocomplementemia, and discoid skin rash. After combined therapy consisting of plasma exchange, HD, and steroid pulse, the patient made a good recovery without any residual neurological sequelae, though kidney dysfunction requiring maintenance HD remained. Anti-GBM antibody finally became undetectable on the 144th hospital day.

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

Goodpasture's 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 Goodpasture's 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. α_134-148 (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 Goodpasture's disease through encoding ARG13 and PRO11 on MHC-DRβ1 chain and presenting T-cell epitope, α_134-148 , with five critical residues.

The pathogenicity of T cell epitopes on human Goodpasture antigen and its critical amino acid motif

Goodpasture antigen, the non‐collagenous domain of α3 chain of type IV collagen [α3(IV)NC1], is the target antigen of anti‐glomerular basement membrane (GBM) antibodies. The pathogenicity of T cell epitopes is not elucidated clearly. In this study, we aim to define the nephritogenic T cell epitopes and its critical amino acid residues. Twenty‐four overlapping linear peptides were synthesized covering the whole sequence of human α3(IV)NC1. Wistar–Kyoto rats were immunized with linear peptides, and experimental autoimmune glomerulonephritis was evaluated. Critical amino acid was identified by the loss of nephritogenic function after each amino acid substitution by alanine. Of the 24 peptides, P14 (α3_127‐148) could induce 90.5% (19/21) of WKY rats developing anti‐GBM glomerulonephritis with proteinuria, elevated serum urea and creatinine, IgG linear deposit on GBM and substantial (in average 82.4 ± 5.6%) crescent formation in glomeruli. Lymphocytes of immunized rats proliferated in response to α3_127‐148 and α3(IV)NC1 in vitro. Sera of these rats recognized α3_127‐148 and later on together with intact human α3(IV)NC1. Antibodies towards α3_127‐148 and intact α3(IV)NC1 could also be detected from the kidney elutes. These antibodies showed no cross‐reaction with each other, which implies intramolecular epitope spreading during disease progress. After sequential amino acid substitution, the α3_127‐148 with substitution of tryptophan₁₃₆, isoleucine₁₃₇, leucine₁₃₉ or tryptophan₁₄₀ lost its nephritogenicity. Human α3_127‐148 is a nephritogenic T cell epitope in WKY rats, with the critical amino acids as W₁₃₆I₁₃₇xL₁₃₉W₁₄₀. These findings might facilitate future investigation on microbial aetiology and potential specific immunotherapy of anti‐GBM disease.

A case of PR3-ANCA-positive anti-GBM disease associated with intrarenal arteritis and thrombotic microangiopathy

Coexistence of anti-glomerular basement membrane (anti-GBM) disease with anti-neutrophil cytoplasmic antibody (ANCA) is occasionally reported and termed "double positive" disease. Interestingly, the majority of "double positive" ANCA is myeloperoxidase (MPO)-ANCA, and some of the MPO-ANCA-positive cases reveal intrarenal arteritis indicating an ANCA-associated renal lesion. In contrast, proteinase 3 (PR3)-ANCA-positive "double positive" disease had rarely been reported, and as far as we know, none of the cases showed intrarenal arteritis. Herein, we report a case of PR3-ANCA-positive "double positive" anti-GBM disease presenting with pulmonary-renal syndrome and hemolytic uremic syndrome. The kidney biopsy showed crescentic glomerulonephritis, intrarenal arteritis, and thrombotic microangiopathy. This case newly describes PR3-ANCA-associated intrarenal arteritis in "double positive" anti-GBM disease.

Basement membranes and autoimmune diseases

Basement membrane components are targets of autoimmune attack in diverse diseases that destroy kidneys, lungs, skin, mucous membranes, joints, and other organs in man. Epitopes on collagen and laminin, in particular, are targeted by autoantibodies and T cells in anti-glomerular basement membrane glomerulonephritis, Goodpasture's disease, rheumatoid arthritis, post-lung transplant bronchiolitis obliterans syndrome, and multiple autoimmune dermatoses. This review examines major diseases linked to basement membrane autoreactivity, with a focus on investigations in patients and animal models that advance our understanding of disease pathogenesis. Autoimmunity to glomerular basement membrane type IV is discussed in depth as a prototypic organ-specific autoimmune disease yielding novel insights into the complexity of anti-basement membrane immunity and the roles of genetic and environmental susceptibility.

Identification of critical residues of linear B cell epitope on Goodpasture autoantigen

Background

The autoantigen of anti-glomerular basement membrane (GBM) disease has been identified as the non-collagenous domain 1 of α3 chain of type IV collagen, α3(IV)NC1. Our previous study revealed a peptide on α3(IV)NC1 as a major linear epitope for B cells and potentially nephrogenic, designated as P14 (α3129-150). This peptide has also been proven to be the epitope of auto-reactive T cells in anti-GBM patients. This study was aimed to further characterize the critical motif of P14.

Methods

16 patients with anti-GBM disease and positive anti-P14 antibodies were enrolled. A set of truncated and alanine substituted peptides derived from P14 were synthesized. Circulating antibodies against the peptides were detected by enzyme linked immunosorbent assay (ELISA).

Results

We found that all sera with anti-P14 antibodies reacted with the 13-mer sequence in the C-terminus of P14 (P14c) exclusively. The level of antibodies against P14 was highly correlated with the level of antibodies against P14c (r=0.970, P<0.001). P14c was the core immunogenic region and the amino acid sequence (ISLWKGFSFIMFT) was highly hydrophobic. Each amino acid residue in P14c was sequentially replaced by alanine. Three residues of glycine142, phenylalanine143, and phenylalanine145 were identified crucial for antibody binding based on the remarkable decline (P<0.001) of antibody reaction after each residue replacement.

Conclusions

We defined GFxF (α3142, 143,145) as the critical motif of P14. It may provide some clues for understanding the etiology of anti-GBM disease.

HLA class I and class II associations with ESRD in Saudi Arabian population

Background

Chronic renal failure (CRF) leads in the majority of instances to end stage renal disease (ESRD) requiring renal replacement therapy. Our interest was to evaluate the possible associations of HLA class I and class II antigens with ESRD independent of other factors, in Saudi Arabia population.

Methodology

A retrospective study to determine the HLA class I and class II polymorphisms and their association with ESRD, was performed on 350 patients with ESRD, and 105 healthy unrelated control. Patients and control groups were typed by SSOP lumenix techniques. The alleles positively associated to the ESRD were: HLA-B*15, B*18, B*49 - DRB1*03, negatively associated alleles were A*26, HLA-B*39, B*50. The haplotypes positively associated with ESRD were: HLA-A*01-DRB1*13 and HLA-A*30-DRBI*03. The negatively associated haplotypes were: HLA-A*02-B*39, A*02-B*50, A*24-B*35, A*24-B*58, A*24-DRB1*16, A*68-DRB1*04, A*02-DQB1*03, A*29-DQB1*02, A*29-DOB1*05 and B*27-DRB1*07 and the last one is the most significant protective haplotypes.

Conclusion

The high Relative Risk (RR) observed and its statistical correlation reflect the strength of the described association between HLA antigens and ESRD.

Identical twins:one with anti-glomerular basement membrane glomerulonephritis,the other with systemic lupus erythematosus

BACKGROUND

Anti-glomerular basement membrane (GBM) glomerulonephritis and systemic lupus erythematosus (SLE) are both disorders of the immune system; however, they are known as distinct diseases. Till now no clinical evidence suggests the genetic relationship between these two diseases. Herein, we present two identical twins; one was diagnosed as anti-GBM glomerulonephritis, the other SLE. This is the first clinical report on the genetic relationship between these two diseases.

CASE PRESENTATION

A 25-year-old female was admitted complaining of intermittent gross hematuria for 6 months and elevated serum creatinine for 1 month. She denied hemoptysis. Laboratory examinations showed hemoglobin 7.4 g/dL, serum creatinine 7.15 mg/dL and albumin 2.8 g/dL. Urinalysis showed hematuria (484 RBCs per high-power field) and proteinuria 4+. Antinuclear antibody, complement levels and ANCAs were all normal. Renal ultrasound showed normal-sized kidneys without obstruction or masses. Serum anti-GBM antibody assay showed 119.70 RU/mL (normal range, <20 RU/mL). Chest X-ray was normal. She was diagnosed as anti-GBM glomerulonephritis and received plasma exchange (2000-3000 ml plasma/exchange, 5 turns), methylprednisolone 0.5 g for three days, plus cyclophosphamide. Although serum anti-GBM antibodies decreased gradually to a normal range, her renal function did not improve. One month later, her identical twin sister was diagnosed as SLE based on malar erythema, arthralgia, antinuclear antibody positive with liter 1:1000, and Anti-Smith (Sm) antibody ++. Anti-GBM antibody and complements were within normal ranges. Further study showed these twins were HLA-DRB1*1501 homozygotes.

CONCLUSION

The presence of identical twins having anti-GBM nephritis and SLE respectively provides clinical evidence to support that anti-GBM nephritis and lupus may share a common genetic background to some extent, while environment may contribute to disease evolution in part.

Crescentic glomerulonephritis: new aspects of pathogenesis

This review provides a summary of recent advances in the understanding of crescentic glomerulonephritis, focusing on antineutrophil cytoplasm antibody (ANCA)-associated vasculitis and anti-glomerular basement membrane (anti-GBM) antibody disease. In ANCA-associated vasculitis (AAV), four main conceptual advances are discussed as follows: (1) evidence for the pathogenicity of ANCA, (2) molecular mimicry and the role of infection in AAV, (3) evidence for aberrant T-cell responses and T-cell regulation in AAV, and (4) advances in understanding of genetic predisposition to AAV. In relation to anti-GBM disease we discuss the following: (1) the nature of the Goodpasture autoantigens, (2) T-cell responses and regulation in anti-GBM disease, and (3) human leukocyte antigen and non-human leukocyte antigen genetic associations.

The association of HLA-DQB1, -DQA1 and -DPB1 alleles with anti- glomerular basement membrane (GBM) disease in Chinese patients

Background

Human leukocyte antigen (HLA) alleles are associated with many autoimmune diseases, including anti-glomerular basement membrane (GBM) disease. In our previous study, it was demonstrated that HLA-DRB1*1501 was strongly associated with anti-GBM disease in Chinese. However, the association of anti-GBM disease and other HLA class II genes, including HLA-DQB1, -DQA1,-DPB1 alleles, has rarely been investigated in Asian, especially Chinese patients. The present study further analyzed the association between anti-GBM disease and HLA-DQB1, -DQA1, and -DPB1 genes. Apart from this, we tried to locate the potential risk amino acid residues of anti-GBM disease.

Methods

This study included 44 Chinese patients with anti-GBM disease and 200 healthy controls. The clinical and pathological data of the patients were collected and analyzed. Typing of HLA-DQB1, -DQA1 and -DPB1 alleles were performed by bi-directional sequencing of exon 2 using the SeCoreTM Sequencing Kits.

Results

Compared with normal controls, the prevalence of HLA-DPB1*0401 was significantly lower in patients with anti-GBM disease (3/88 vs. 74/400, p = 4.4 × 10^-4, pc = 0.039). Comparing with normal controls, the combination of presence of DRB1*1501 and absence of DPB1*0401 was significantly prominent among anti-GBM patients (p = 2.0 × 10^-12, pc = 1.7 × 10^-10).

Conclusions

HLA-DPB1*0401 might be a protective allele to anti-GBM disease in Chinese patients. The combined presence of DRB1*1501 and absence of DPB1*0401 might have an even higher risk to anti-GBM disease than HLA-DRB1*1501 alone.

Interstitial lung diseases in children

Interstitial lung disease (ILD) in infants and children comprises a large spectrum of rare respiratory disorders that are mostly chronic and associated with high morbidity and mortality. These disorders are characterized by inflammatory and fibrotic changes that affect alveolar walls. Typical features of ILD include dyspnea, diffuse infiltrates on chest radiographs, and abnormal pulmonary function tests with restrictive ventilatory defect and/or impaired gas exchange. Many pathological situations can impair gas exchange and, therefore, may contribute to progressive lung damage and ILD. Consequently, diagnosis approach needs to be structured with a clinical evaluation requiring a careful history paying attention to exposures and systemic diseases. Several classifications for ILD have been proposed but none is entirely satisfactory especially in children. The present article reviews current concepts of pathophysiological mechanisms, etiology and diagnostic approaches, as well as therapeutic strategies. The following diagnostic grouping is used to discuss the various causes of pediatric ILD: 1) exposure-related ILD; 2) systemic disease-associated ILD; 3) alveolar structure disorder-associated ILD; and 4) ILD specific to infancy. Therapeutic options include mainly anti-inflammatory, immunosuppressive, and/or anti-fibrotic drugs. The outcome is highly variable with a mortality rate around 15%. An overall favorable response to corticosteroid therapy is observed in around 50% of cases, often associated with sequelae such as limited exercise tolerance or the need for long-term oxygen therapy.

The role of HLA-DRB1 alleles on susceptibility of Chinese patients with anti-GBM disease

Anti-glomerular basement membrane (GBM) disease, a rare autoimmune disorder, is associated with HLA-DR15 genotype in Caucasian and Japanese populations. But the distribution of HLA-DRB1 alleles in Chinese patients with anti-GBM disease and their association with clinical characteristics of anti-GBM disease are to be determined. The present study analyzed the HLA-DRB1 alleles by sequence based typing in 44 Chinese patients with anti-GBM disease and 200 healthy controls. The effects of DRB1 alleles on susceptibility to anti-GBM disease were examined by a relative predispositional effects (RPEs) method. The clinical and pathological data of the patients were collected and analyzed. The DRB1*1501 allele was significantly associated with anti-GBM disease (p=1.597 x 10(-7)). The RPEs test also showed a significant increased frequency of DRB1*0404 in anti-GBM disease (p=0.037). Interestingly, the patients with DRB1*1501 or 0404 had more crescent formation in glomeruli than those without the two alleles (p=0.021). But the DRB1*0404 was rare in both patients and control groups, which indicates that the importance of the *0404 allele is limited in anti-GBM disease. We conclude that the HLA-DRB1*1501 allele is a genetic marker for susceptibility to anti-GBM disease.

FCGR2B gene polymorphism rather than FCGR2A, FCGR3A and FCGR3B is associated with anti-GBM disease in Chinese

BACKGROUND

The Fcgamma receptors play important roles in anti-glomerular basement membrane antibody disease (anti-GBM disease) in animal models, and FCGR gene polymorphisms have been reported to be associated with numerous human autoimmune diseases. We aimed to clarify the genetic association of FCGR gene polymorphisms with anti-GBM disease in Chinese patients.

METHODS

A total of 48 patients with anti-GBM disease and 225 geographically and ethnically matched healthy controls were involved. Genotyping of the previously identified polymorphisms FCGR2A131H/R (rs1801274), FCGR2B 232I/T (rs1050501) and FCGR3A176F/V (rs396991) were detected by the TaqMan genotyping assay and FCGR3B NA1/2 by the PCR-sequence specific primer (SSP). Allele type, genotype and haplotype of identified polymorphisms were analysed between patients and controls.

RESULTS

Our results revealed that FCGR2A131H/R, FCGR3A176F/V and FCGR3B NA1/2 were not associated with anti-GBM disease. The frequency of the FCGR2B 232T allele (30.2% versus 15.6%, corrected P = 0.00028, 95% CI: 1.42-3.89) and genotypes of I232T (60.4% versus 31.1%, corrected P = 0.0004, 95% CI: 1.78-6.43) was significantly increased in patients compared with controls.

CONCLUSION

The present study demonstrates the genetic association of polymorphism of FCGR2B (I232T) with susceptibility to anti-GBM disease in Chinese.