The influence of HLA-linked genes on the severity of anti-GBM antibody-mediated nephritis

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.

Pulmonary renal syndrome: a clinical review

The term "pulmonary renal syndrome" describes a clinical syndrome which is characterised by the presence of both diffuse alveolar haemorrhage and glomerulonephritis. It encompasses a group of diseases with distinctive clinical and radiological manifestations, as well as different pathophysiological processes. The most common diseases implicated are anti-neutrophil cytoplasm antibodies (ANCA)-positive small vessel vasculitis and anti-glomerular basement membrane (anti-GBM) disease. Prompt recognition is required as respiratory failure and end-stage renal failure can rapidly occur. Treatment includes a combination of glucocorticoids, immunosuppression, plasmapheresis and supportive measures. The use of targeted treatments has significantly reduced mortality. Thus, an understanding of pulmonary renal syndrome is essential for the respiratory physician.

Association between human leucocyte antigen subtypes and risk of end stage renal disease in Taiwanese: a retrospective study

Background

End stage renal disease (ESRD) is prevalent in Taiwan. Human leukocyte antigens (HLA) have been found to be associated with the pathogenesis of autoimmune diseases, allergies and inflammatory bowel diseases, and there are emerging evidences of correlations between HLA genotypes and renal diseases such as diabetic nephropathy, IgA nephropathy, and glomerulonephritis. The aim of this study is to investigate detailed HLA subtypes in a case-control study of Taiwanese individuals.

Methods

The polymorphisms of HLA class I and II antigens in ESRD patients and a healthy control group were retrospectively analyzed. The information of 141 ESRD patients was obtained from the medical record of the Keelung branch of Chang Gung Memorial Hospital and was compared to the HLA type of a control group comprized of 190 healthy unrelated Taiwanese from one of our previous studies. In order to standardize the HLA designation of prior low-resolution typings with the more advanced DNA based typings, all HLA-A, −B and -DR were analyzed using a low resolution serologic equivalent.

Results

The current work suggests that HLA-DR3 (odds ratio = 1.91, 95 % CI = 1.098–3.324, P = 0.024, Pc = 0.312) and HLA-DR11 (odds ratio = 2.06, 95 % CI = 1.133–3.761, P = 0.021, Pc = 0.273) may represent susceptibility risk factors for the development of ESRD in Taiwanese individuals. On the other hand, HLA-DR8 (odds ratio = 0.47, 95 % CI = 0.236–0.920, p = 0.027. Pc = 0.351) may be a protective factor. HLA-A and -B antigens did not show any contribution of progression to ESRD. However, we note that the significance of all these findings is lost when the results are corrected for multiple comparisons according to Bonferroni. Further investigation with a larger group of patients and control is needed to resolve this issue.

Conclusions

HLA typing might be a useful clinical method for screening patients with high risk of progression to ESRD.

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.

The many faces of Goodpasture's syndrome

Four cases of antiglomerular basement membrane (antiGBM) antibody mediated disease with unusual features are presented. Lung involvement was absent in one patient whereas the other 3 had Goodpasture's syndrome. Recognition of the nature of the disease was delayed in all cases, due to occurrence during pregnancy in one case and due to the indolent course of the renal injury in the other 3 cases. The therapeutic approach to these variant forms of antiGBM antibody mediated disease is discussed.

Pulmonary-renal syndromes

Pulmonary-renal syndromes or lung-kidney syndromes are clinical syndromes defined by a combination of diffuse alveolar haemorrhage (DAH) and glomerulonephritis. Pulmonary-renal syndromes are not a single entity, but are caused by a wide variety of diseases, including various forms of primary systemic vasculitis (especially Wegener's granulomatosis and microscopic polyangiitis), Goodpasture's syndrome (associated with autoantibodies to the alveolar and glomerular basement membrane) and systemic lupus erythematosus. The diagnosis rests on the identification of particular patterns of clinical, radiologic, pathologic and laboratory features. Serologic testing is important in the diagnostic work-up of patients presenting with a pulmonary-renal syndrome. The majority of cases of pulmonary-renal syndrome are associated with ANCAs, either c-ANCA or p-ANCA, due to autoantibodies against the target antigens proteinase-3 and myeloperoxidase respectively. The antigen target in Goodpasture's syndrome is type IV collagen, the major component of basement membranes. Diffuse alveolar haemorrhage is characterized by the presence of a haemorrhagic bronchoalveolar lavage (BAL) in serial BAL samples. In the clinical setting of an acute nephritis syndrome, percutaneous renal biopsy is commonly performed for histopathology and immunofluorescence studies. Treatment of generalized ANCA-associated vasculitis consists of corticosteroids and immunosuppressive agents such as cyclophosphamide (as induction therapy) or azathioprine (as maintenance therapy once remission has been achieved). The combination of plasmapheresis with these cytotoxic agents and steroids is effective in patients with Goodpasture's syndrome, especially if instituted early in the course of the disease. Recent evidence suggests that patients with severe ANCA-associated vasculitis, defined by the presence of diffuse alveolar haemorrhage and/or severe renal involvement (creatinine concentration > 5.7 mg/dl), might benefit from plasma exchange in combination with cyclophosphamide and corticosteroids.

Insulin-dependent diabetes loci Idd5 and Idd9 increase sensitivity to experimental autoimmune encephalomyelitis

The spontaneous development of autoimmune diabetes in NOD mice suggests that they are unable to establish and maintain immunologic self-tolerance. Congenic NOD mice expressing B10-derived alleles are protected from pancreatic beta cell destruction and autoimmune diabetes. To determine if the B10 alleles in loci Idd5 and Idd9 could influence susceptibility to autoimmunity in other organs, we compared MOG35-55-induced EAE in NOD mice to that of diabetes-resistant NOD.B10.Idd5 and NOD.B10.Idd9 mice. Surprisingly, the severity and chronicity of EAE were enhanced in the diabetes-resistant congenic mice. Our findings indicate that some alleles may influence susceptibility to immune-mediated damage in an organ or tissue-specific fashion, and highlight the necessity of disease-specific investigations.

Reactive oxygen species expose cryptic epitopes associated with autoimmune goodpasture syndrome

Goodpasture syndrome is an autoimmune disease of the kidneys and lungs mediated by antibodies and T-cells directed to cryptic epitopes hidden within basement membrane hexamers rich in alpha3 non-collagenous globular (NC1) domains of type IV collagen. These epitopes are normally invisible to the immune system, but this privilege can be obviated by chemical modification. Endogenous drivers of immune activation consequent to the loss of privilege have long been suspected. We have examined the ability of reactive oxygen species (ROS) to expose Goodpasture epitopes buried within NC1 hexamers obtained from renal glomeruli abundant in alpha3(IV) NC1 domains. For some hexameric epitopes, like the Goodpasture epitopes, exposure to ROS specifically enhanced recognition by Goodpasture antibodies in a sequential and time-dependent fashion; control binding of epitopes to alpha3(IV) alloantibodies from renal transplant recipients with Alport syndrome was decreased, whereas epitope binding to heterologous antibodies recognizing all alpha3 NC1 epitopes remained the same. Inhibitors of hydrogen peroxide and hydroxyl radical scavengers were capable of attenuating the effects of ROS in cells and kidney by 30-50%, respectively, thereby keeping the Goodpasture epitopes largely concealed when compared with a 70% maximum inhibition by iron chelators. Hydrogen peroxide administration to rodents was sufficient to expose Goodpasture epitope in vivo and initiate autoantibody production. Our findings collectively suggest that ROS can alter the hexameric structure of type IV collagen to expose or destroy selectively immunologic epitopes embedded in basement membrane. The reasons for autoimmunity in Goodpasture syndrome may lie in an age-dependent deterioration in inhibitor function modulating oxidative damage to structural molecules. ROS therefore may play an important role in shaping post-translational epitope diversity or neoantigen formation in organ tissues.

Identification of alpha3, alpha4, and alpha5 chains of type IV collagen as alloantigens for Alport posttransplant anti-glomerular basement membrane antibodies

BACKGROUND

Alport syndrome is a hereditary disorder of basement membranes especially affecting the kidneys, ears, and eyes. Some patients who undergo renal transplantation lose their kidneys as a result of posttransplant anti-glomerular basement membrane (anti-GBM) disease.

METHODS

In the present study, we analyzed serum from 21 unselected Alport patients who underwent renal transplantation. Eleven samples were from patients without posttransplant anti-GBM nephritis, and 10 were from patients with this disease.

RESULTS

Thirteen serum samples [10 alport posttransplant nephritis serum (APTN) and three Alport posttransplant serum (APT)] revealed linear binding to the GBM by indirect immunofluorescence. By using direct ELISA and immunoblotting with GBM constituents and type IV collagen NC1 domains from bovine, human, and recombinant sources, we detected anti-GBM antibodies in all Alport patients in varying titers. Five samples showed specific reactivity to the alpha3 chain, four to the alpha5 chain, six to both alpha3 and alpha5 chains, one to the alpha3 and alpha4 chains, and two to the alpha3, alpha4, and alpha5 chains of type IV collagen. The varied spectrum of reactivities was present equally in nephritic and non-nephritic sera. Ten control samples from non-Alport transplant patients did not exhibit specific binding to the GBM.

CONCLUSIONS

These results suggest that the absence of alpha3, alpha4, and alpha5 chains of type IV collagen in the Alport kidney leads to alloantibodies in all Alport patients who receive transplants, irrespective of whether they develop nephritis or not. Although all Alport transplant patients develop this humoral response, only a select few develop anti-GBM disease. We suggest that this difference could be attributable to a genotypic effect on the ability of some individuals to launch a cell-mediated immune response.

The HLA complex in Goodpasture's disease: a model for analyzing susceptibility to autoimmunity

Human lymphocyte antigen (HLA) associations are recognized for many autoimmune diseases, but the mechanisms are not clear. Goodpasture's disease provides a unique opportunity to investigate possible mechanisms because strong HLA associations are known, the autoantigen is well defined, and major antigen-derived peptides presented bound to HLA molecules have been identified. Therefore, it may be possible to directly analyze interactions between the antigen and HLA molecules associated with the disease, and to examine influences on antigen presentation to T cells. Towards this goal, we present a detailed analysis of HLA associations with the disease and examine molecular mechanisms that could account for them.

Pulmonary manifestations of Goodpasture's syndrome. Antiglomerular basement membrane disease and related disorders

Goodpasture's syndrome, or antiglomerular basement membrane disease, is a disorder in which lungs and kidneys are affected by the binding of anti-GBM antibodies, leading to pulmonary hemorrhage and glomerulonephritis with rapidly progressive renal insufficiency. Recent advances in the understanding of disease pathogenesis and diagnosis and treatment have significantly improved our ability to recognize the syndrome, distinguish it from other similar disorders, and offer successful treatment. This article focuses on the pathogenetic features, clinical manifestations, diagnostic strategies, and therapeutic principles of anti-GBM disease.

HLA antigens in childhood onset schizophrenia

Evidence of immune system abnormalities in adult schizophrenia has prompted examination of the human leukocyte antigen (HLA) system. Childhood onset schizophrenia offers a unique opportunity to test neurodevelopmental hypotheses of schizophrenia, including those which implicate components of the immune system. In the present study, class I and II HLA antigens were typed using sequence-specific primers and the polymerase chain reaction in 28 childhood onset schizophrenics and 51 ethnically matched healthy subjects. Groups were compared for frequencies of HLA antigens reported to be associated with schizophrenia and/or autoimmune disorders. We hypothesized that antigen frequencies would differ between schizophrenic and healthy children, suggesting that some dimension of the neurodevelopmental disturbance experienced by these children may be mediated by subtle abnormalities of immune function. There were no significant differences between schizophrenic and healthy subjects in the frequency of any antigen tested. These findings do not support HLA-associated pathology in childhood onset schizophrenia.

Association of Alport's syndrome with HLA-DR2 antigen in a group of unrelated patients

A few family studies have evaluated HLA antigens in Alport's syndrome; however, there are no large population studies. In the present report, we studied 40 unrelated white patients with Alport's syndrome seen at the Unit of Renal Transplantation, Faculty of Medicine of Ribeirão Preto, São Paulo, Brazil. HLA-A, -B, -DR and -DQ antigens were typed using a complement-dependent microlymphocytotoxicity assay. A control white population (N = 403) from the same geographical area was also typed for HLA antigens. Although the frequencies of HLA-A and -B antigens of patients were not statistically different from controls, the frequency of HLA-DR2 antigen observed in patients (65%) was significantly increased in relation to controls (26%; P < 0.001). The relative risk and etiologic fraction for HLA-DR2 antigen were 5.2 and 0.525, respectively. Although few immunological abnormalities have been shown in Alport's syndrome, in this report we emphasize the association of HLA molecules and Alport's syndrome. Besides the well-known inherited molecular defects encoded by type IV collagen genes in Alport's syndrome, the major histocompatibility alleles may be in linkage disequilibrium with these defective collagen genes.

Susceptibility to anti-glomerular basement membrane disease and Goodpasture syndrome is linked to MHC class II genes and the emergence of T cell-mediated immunity in mice

We developed a new mouse model of human anti-glomerular basement membrane (GBM) disease to better characterize the genetic determinants of cell-mediated injury. While all major histocompatibility complex (MHC) haplotypes (H-2a, k, s, b, and d) immunized with alpha3 NC1 domains of type IV collagen produce anti-alpha3(IV) NC1 antibodies that cross-react with human Goodpasture [anti-GBM/anti-alpha3(IV) NC1] autoantibodies, only a few strains developed nephritis and lung hemorrhage associated with Goodpasture syndrome. Crescentic glomerulonephritis and lung hemorrhage were MHC-restricted in haplotypes H-2s, b, and d (A beta/A alpha region in H-2s) and associated with the emergence of an IL-12/Th1-like T cell phenotype. Lymphocytes or anti-alpha3(IV) NC1 antibodies from nephritogenic strains transfer disease to syngeneic recipients. However, passive transfer of isogenic alpha3(IV) NC1 antibodies into -/- T cell receptor-deficient mice failed to produce nephritis. Finally, nephritis and its associated IL-12/Th1-like T cell response attenuate in disease-susceptible mice tolerized orally to alpha3(IV) collagen before immunization. Our findings suggest collectively, as a hypothesis, that anti-GBM antibodies in mice only facilitate disease in MHC haplotypes capable of generating nephritogenic lymphocytes with special T cell repertoires.

Susceptibility to anti-glomerular basement membrane disease is strongly associated with HLA-DRB1 genes

Anti-glomerular basement membrane (anti-GBM) disease is caused by autoimmunity to a component of glomerular basement membrane. The major autoantigen has been identified as the NC1 domain of the alpha 3 chain of type IV collagen, and patients are characterized by the presence of specific autoantibodies to this molecule. In common with other autoimmune disorders, there is a strong association with HLA genes, with up to 80% of patients inheriting an HLA-DR2 haplotype. To examine the genetic basis of susceptibility to anti-GBM disease in more detail, the HLA-DRB and DQB alleles inherited by 82 patients were analyzed using sequence specific oligonucleotides. This identified a hierachy of association of DRB1 genes with anti-GBM disease, including susceptibility (DRB1*15, DRB1*04), neutral (DRB1*03) and protective (DRB1*07) alleles. Analysis of inherited haplotypes, particularly DRB1*04 and DRB1*07 carrying haplotypes, provided further evidence that the primary association was with genes at the DRB1 locus. Comparison of the sequences of the positively and negatively associated alleles showed that polymorphic residues in the second peptide binding region of the HLA Class II antigen binding groove segregated with disease. This work supports the hypothesis that the HLA associations in anti-GBM disease reflect the ability of certain Class II molecules to bind and present peptides derived from the autoantigen to T helper cells.

Recurrent Goodpasture's disease

Goodpasture's disease is usually a monophasic illness that can be successfully treated in a large proportion of patients. Recurrent disease is rare. We report a case of Goodpasture's disease in which recurrent pulmonary hemorrhage and glomerulonephritis were observed over 12 years. Antiglomerular basement membrane autoantibody was monitored throughout this period, and we demonstrate the close association of antibody levels with disease recurrence.

[Goodpasture syndrome: role of an epidemiological factor? Apropos of two cases]

Goodpasture's syndrome is a rare pneumorenal syndrome. Although the antigenic target of this auto-immune disorder is now known, its etiology remains debated. We report two cases of Goodpasture's syndrome occurring in similar epidemiologic conditions concerning the moment the disease began, the age and sex of the patients, their place of residence and work and manipulation of chemicals. Thus, a common environmental factor could have been the trigger event of the Goodpasture's syndrome. The epidemiologic features of this disease are reviewed.

Progression from Goodpasture's disease to membranous glomerulonephritis

An unusual case of a patient with Goodpasture's disease presenting with hemoptysis, severe iron deficiency anemia and microscopic hematuria and proteinuria is described. Both circulating and tissue anti-glomerular basement membrane (GBM) antibodies were present, and renal function remained normal throughout. Immunosuppressive therapy was given for subclinical pulmonary hemorrhage with successful resolution of anemia and disappearance of the circulating anti-GBM antibody. Nine months after presentation he developed nephrotic range proteinuria and a repeat renal biopsy revealed membranous glomerulonephritis with no evidence of his original disease. Both the Goodpasture's associated HLA-DR2 and the membranous associated HLA-DR3 class II antigens were present. The association of antibody mediated and immune complex glomerulonephritis is discussed. The simultaneous presence of HLA-DR2 and HLA-DR3 may predispose to this association.

Fundamental concepts and immunosuppressive treatment in the various forms of glomerulonephritis

Immunosuppressive treatment in glomerulonephritis (GN) is still controversial. Most of the secondary forms of glomerulonephritis have the histologic features of one of the primary types of glomerulonephritis. Eight histologic expressions of primary glomerulonephritis can be distinguished and ordered in terms of severity of symptoms and prognosis: endocapillary GN, minimal change GN, mesangioproliferative GN, membranous GN, focal-sclerosing GN, membranoproliferative GN, focal-necrotizing GN, and rapidly progressive GN. Agreement exists only to the extent that immunosuppression is not required in endocapillary glomerulonephritis, although it is recommended in the other extreme of rapidly progressive GN. Primarily, an indication for immunosuppression is given by the severity of symptoms with a urinary protein excretion > 3.5 g per day and/or serum creatinine > 150 mumol per liter. As for anti-GBM, the type of glomerulonephritis is more important than the severity of symptoms in guiding therapy, whereas for IgA nephropathy it is controversial whether the prospective prognosis of even inexorably deteriorating renal function justifies immunosuppression. Renal biopsy is required to identify the type of glomerulonephritis so as to establish the specific immunosuppressive concept with different intensity and duration of treatment. Immunosuppression can reduce urinary protein excretion and improve deterioration of renal function; however, the proportion of patients responding varies with and depends on the different forms of GN.

The alpha 3 chain of type IV collagen induces autoimmune Goodpasture syndrome

Human Goodpasture syndrome is a lethal form of autoimmune disease that is characterized by pulmonary hemorrhage and glomerulonephritis. The tissue injury is mediated by autoantibodies that bind to glomerular and alveolar basement membrane. The target autoantigen is alpha 3(IV) collagen, one of six genetically distinct chains that comprise type IV collagen, and the epitope is sublocalized to the noncollagenous domain (NC1) of the alpha 3 chain. The present study reports the unique capacity of alpha 3(IV)NC1 dimer from bovine kidney to aberrantly engage the immune system of rabbits to respond to self, mimicking the organ-specific form of the human disease, whereas the other chains of type IV collagen are nonpathogenic. However, alpha 3(IV)NC1 hexamer was nonpathogenic, suggesting the exposure of a pathogenic epitope upon dissociation of hexamer into dimers. Exposure of the pathogenic epitope by infection or organic solvents, events which are thought to precede Goodpasture syndrome, may be the principal factor in the etiology of the disease. The pathogenicity of alpha 3(IV) collagen brings full circle a decade of research that has identified four novel chains (alpha 3-alpha 6) of type IV collagen.

COL4A5 gene deletion and production of post-transplant anti-alpha 3(IV) collagen alloantibodies in Alport syndrome

Mutations in the COL4A5 gene encoding the alpha 5(IV) chain of type IV collagen have been implicated as the primary defect in X-linked Alport syndrome. Several kinds of mutations have been reported so far, spanning point mutations to complete gene deletions. About 5% of Alport patients, who undergo renal transplantation, develop anti-glomerular basement membrane (GBM) nephritis, causing loss of allograft function. In one such patient, COL4A5 gene deletion was recently identified. In the present study, the GBM constituent, targeted by the anti-GBM alloantibodies from the patient who had complete COL4A5 gene deletion was identified. Its identity was determined on the basis of circulating antibody binding to various GBM constituents, domains of bovine type IV collagen and recombinant NC1 domain of human type IV collagen. These results establish, for the first time, the absence of the alpha 5(IV) chain in Alport GBM and, in the same patient, the production of an alloantibody that is targeted to a different chain of type IV collagen, the alpha 3(IV) chain. These findings provide further support for the hypothesis that: (1) anti-alpha 3(IV) collagen alloantibodies mediate the allograft glomerulonephritis; and (2) COL4A5 gene mutations cause defective assembly of the alpha 3(IV) collagen alloantibodies mediate the allograft glomerulonephritis; and (2) COL4A5 gene mutations cause defective assembly of the alpha 3(IV) chain in Alport GBM, as reflected by the production of anti-alpha 3(IV) alloantibodies.

Molecular cloning of the human Goodpasture antigen demonstrates it to be the alpha 3 chain of type IV collagen

To characterize the autoantigen of Goodpasture's (anti-glomerular basement membrane) disease, a molecule of 26-kD reactive with autoantibodies from patients' sera was purified from collagenase digests of sheep glomerular basement membrane. Short internal amino acid sequences were obtained after tryptic or cyanogen bromide cleavage, and used to deduce redundant oligonucleotides for use in the polymerase chain reaction on cDNA derived from sheep renal cortex. Molecules of 175 bp were amplified and found to come from two cDNA sequences. One was identical to that of a type IV collagen chain (alpha 5) cloned from human placenta and shown to be expressed in human kidney. The other was from a type IV collagen chain with close similarities to alpha 1 and alpha 5 chains, and was used to obtain human cDNA sequences by cDNA library screening and by further polymerase chain reaction amplifications. The correspondence of the derived amino acid sequence of the new chain with published protein and cDNA sequences shows it to be the alpha 3 chain of type IV collagen. Its gene, COL4A3, maps to 2q36-2q37. The primary sequence and other characteristics of this chain confirm that it carries the Goodpasture antigen.

Vancomycin and teicoplanin: something old, something new

OBJECTIVE

To compare and contrast the pharmacology, activity and clinical efficacy of two glycopeptide antibiotics, vancomycin and teicoplanin.

DATA SOURCES

English language literature search using MEDLINE, Index Medicus, relevant textbooks and product information literature.

STUDY SELECTION

Over 200 publications were examined extending back to the period of initial Phase I trials with vancomycin.

DATA EXTRACTION AND SYNTHESIS

Many publications covered similar ground and came to the same conclusions. In these instances one or two of the best pieces were chosen as cited reference material. Conflicting results and conclusions are discussed and an attempt is made to interpret the findings.

CONCLUSION

Vancomycin and teicoplanin show differences in activity both in vitro and in vivo. Vancomycin is superior against coagulase-negative staphylococci and reliable dosage regimens are available. Teicoplanin, however, needs to be given in significantly larger doses than initially thought necessary to maximise clinical efficacy. Teicoplanin has a lower incidence of side effects but in clinical practice this advantage is small. Vancomycin remains the glycopeptide of choice for the treatment of infections due to Gram-positive bacteria.

Restricted specificity of the autoantibody response in Goodpasture's syndrome demonstrated by two-dimensional western blotting

The autoantigen in Goodpasture's syndrome is known to be contained within the non-collagenous (NC1) domain of type IV collagen. We have examined the specificity of autoantibodies to glomerular basement membrane (GBM) using the technique of 2-D electrophoresis followed by Western blotting. Protein stains of 2-D gels of collagenase-digested human GBM revealed extensive charge and size heterogeneity. Major components were of mol. wt 24-30 kD and 43-56 kD, corresponding to monomeric and dimeric subunits of NCl. Western blotting of 2-D gels with IgG from patients with anti-GBM disease demonstrated that the most antigenic components migrated as cationic 28-kD monomers (pI 10) and similarly charged dimers, although other components were recognized less strongly. The mobility of the strongly antigenic polypeptides was different to that of the known alpha 1 and alpha 2 chains of type IV collagen. Autoantibodies from all 20 patients studied showed the same pattern of reactivity, regardless of their clinical features (in particular, the presence or absence of pulmonary haemorrhage) or HLA type. A monoclonal antibody (P1) to human GBM bound in a similar pattern, particularly recognizing the cationic components. 2-D gels of affinity-purified GBM from a P1 column showed enrichment of the 28-kD monomers, which were recognized by human autoantibodies on Western blotting. These results demonstrate that the autoimmune response in Goodpasture's syndrome is of restricted specificity, and support the suggestion that the major autoantigenic determinant is present on the novel alpha 3 chain of type IV collagen.

Susceptibility to the induction of either autoimmunity or immunosuppression by mercuric chloride is related to the major histocompatibility complex class II haplotype

Mercuric chloride (HgCl2) induces in Brown Norway rats a CD4+ T lymphocyte-dependent systemic autoimmune syndrome, involving synthesis of anti-glomerular basement membrane autoantibodies and development of proteinuria. Lewis rats are resistant to HgCl2-induced autoantibody production and, in contrast, develop immunosuppression, mediated by CD8+ T lymphocytes. In the present study, genetic requirements governing autoreactivity or immunosuppression in response to HgCl2 were further explored. Both major histocompatibility complex (MHC) and non-MHC genes are involved in determining susceptibility to HgCl2-induced autoimmunity. Both AO (RT1u) and DZB (RT1u) rats were found to develop a membranous autoimmune glomerulopathy upon exposure to HgCl2. Only the DZB strain, which differs in part of the non-MHC background from AO, developed proteinuria. AO.1P (RT1.AuB1D1Eu) rats, which are genetically identical to AO except for the Lewis haplotype at the MHC class II loci, appeared to develop immunosuppression upon exposure to HgCl2. It is concluded that autoreactivity and immunosuppression, induced by HgCl2, are both dependent on the MHC class II haplotype. In autoimmune responder strains the type of autoimmune glomerulopathy is influenced by non-MHC genes.

Rapidly progressive glomerulonephritis: classification, pathogenetic mechanisms, and therapy

Immunopathologic studies over the past two decades have demonstrated that rapidly progressive glomerulonephritis (RPGN) can result from glomerular deposition of anti-GBM antibody, immune complexes, or from some as yet undefined mechanism that does not involve glomerular antibody deposition. The latter process may be cell mediated and resembles a small vessel vasculitis. Most cases of idiopathic RPGN are not accompanied by pathogenic glomerular immunoglobulin deposition. Recent experimental studies of immune mechanisms of glomerular injury have identified several new processes that can induce damage to the capillary wall sufficient to result in crescentic glomerulonephritis (GN). These include direct effects of anti-GBM antibody alone and of the complement C5b-9 (membrane attack) complex, nephritogenic effects of inflammatory effector cells that involve reactive oxygen species and glomerular halogenation, and injury mediated by sensitized lymphocytes independently of antibody deposition. Macrophages have been shown to participate in both intracapillary and extracapillary fibrin deposition and crescent formation as well as to mediate capillary wall damage. The role of resident glomerular cells and cell-cell interactions in glomerulonephritis is still under active investigation. Despite these several advances in understanding immune injury to the glomerulus, therapy for RPGN remains largely empiric. Although the prognosis in RPGN has clearly improved over time, no form of disease-specific therapy has been clearly shown yet to be beneficial in a controlled study. Interpretation of the existing literature on therapy is complicated by the availability of only historical rather than concurrent controls, lack of attention to several variables known to affect disease outcome, and uncertainty regarding bias in favor of reporting positive results. Available data suggests that optimal outcomes may be achieved in anti-GBM nephritis by treatment with steroids, immunosuppression and plasma exchange, particularly when therapy is directed at patients with mild but rapidly progressive disease before oliguria or severe azotemia develop. Pulse steroids are probably the most cost-effective therapy for the idiopathic form of RPGN, but treatment with cytotoxic agents should be considered if clinical or histologic evidence of vasculitis is present.

Anti-glomerular basement membrane antibody-mediated glomerulonephritis due to glue sniffing

A 16-year-old girl developed rapidly progressive glomerulonephritis and renal failure. The disease was associated with high titres of antiglomerular basement membrane antibodies in serum, linear deposits of immunoglobulin G and diffuse epithelial crescents on renal biopsy. Past history revealed heavy smoking and deliberate sniffing of Pattex glue, a mixture of hydrocarbons which possibly may affect the structure of glomerular basement membrane. After treatment by repeated plasmapheresis and drug immunosuppression autoantibodies disappeared from serum but renal function was not influenced. Renal damage is a potential hazard for glue sniffing adolescents.