Heterogeneity of antibodies in Goodpasture syndrome reacting with type IV collagen

Anti-glomerular basement membrane glomerulonephritis following nintedanib for idiopathic pulmonary fibrosis: a case report

BACKGROUND

We report a previously unrecognized and unreported case of a patient with anti-glomerular basement membrane glomerulonephritis following nintedanib, an orally active small molecule tyrosine kinase inhibitor.

CASE PRESENTATION

A 59-year-old Caucasian woman with a history of idiopathic pulmonary fibrosis presented with severe acute kidney injury (creatinine 285 umol/L) secondary to anti-glomerular basement membrane glomerulonephritis disease 4 months after commencement of nintedanib. She had hematuria with red blood cell casts, nephrotic range proteinuria (3.5g/24 hours) and significantly elevated anti-glomerular basement membrane glomerulonephritis titers at 860 chemiluminescent units. A kidney biopsy confirmed severe crescentic glomerulonephritis with linear immunoglobulin G deposition in glomerular basement membrane. Despite the commencement of treatment with plasma exchange and cyclophosphamide, she remained dialysis dependent. Nintedanib was discontinued.

CONCLUSIONS

Onset of acute anti-glomerular basement membrane glomerulonephritis was found to be associated with recent nintedanib use suggesting that nintedanib may be a potential trigger for anti-glomerular basement membrane glomerulonephritis. This case highlights the importance of close monitoring of patients receiving new targeted therapies. Management of novel targeted agents in patients receiving dialysis is challenging because of the scarcity of specific data.

Atypical anti-glomerular basement membrane disease: lessons learned

Anti-glomerular basement membrane (GBM) disease usually pursues a self-limited course, at least from the immunological perspective. In addition, circulating antibodies to cryptic, conformational epitopes within the NC1 domain of the alpha 3 chain of Type IV Collagen are commonly found at the zenith of the clinical disease. However, exceptions to these general rules do occur, as exemplified by two remarkable cases reported in this issue of the Clinical Kidney Journal. The possible explanations for and the lessons learned from these uncommon occurrences are discussed in this short commentary.

Activation of glomerular basement membrane-specific B cells in the renal draining lymph node after T cell-mediated glomerular injury

Linear binding of IgG to the glomerular basement membrane (GBM) is the hallmark of anti-GBM glomerulonephritis (GN). However, the precise mechanism by which diverse autoantibodies to GBM are induced in GN has not been determined. It was demonstrated previously that a single T cell epitope pCol(28-40) derived from collagen IV alpha3 chain not only induced severe GN in Wistar Kyoto rats but also triggered a diversified anti-GBM antibody response through "B cell epitope spreading." In this study, an expansion of T and B cells in the renal draining lymph node (RDLN) of diseased animals after glomerular injury was observed. RDLN was demonstrated to be the location of GBM-specific B cell activation. First, B cells from RDLN of pCol(28-40)-immunized rats produced in vitro anti-GBM antibodies and antinuclear antibodies. Second, B cells specific to the peptidic B cell epitope in pCol(28-40) were absent among expanding B cells in RDLN. Those findings provided a unique opportunity to track activation of diverse GBM-specific B cells in RDLN. Expression of B lymphocyte-induced maturation protein-1, which is involved in differentiation of plasma cells, in B cells of RDLN was detected and further elevated only after T cell-mediated prominent glomerular injury (day 19). This was supported by the fact that anti-GBM antibodies became detectable only after day 20. Those results suggest that T cell-mediated glomerular injury may trigger de novo internal immunization of autoantigens released from damaged GBM, which further leads to activation of a group of GBM-specific B cells in RDLN.

A Self T Cell Epitope Induces Autoantibody Response: Mechanism for Production of Antibodies to Diverse Glomerular Basement Membrane Antigens

The anti-glomerular basement membrane (GBM) Ab has been regarded as a prototypical example of pathogenic autoantibodies. However, the mechanism for elicitation of this Ab remains unknown. In the present paper, we report that the Ab to diverse GBM Ags was induced by a single nephritogenic T cell epitope in a rat model. The T cell epitope pCol(28-40) of noncollagen domain 1 of collagen type IV alpha3 chain not only uniformly induced severe glomerulonephritis but also elicited anti-GBM Ab in 76% of the immunized rats after prominent glomerular injury. Furthermore, we demonstrated that the anti-GBM Ab was not related to the peptidic B cell epitope nested in pCol(28-40); that is, 1) elimination of the B cell epitope, either by substitution of the critical residues of the B cell epitope or by truncation, failed to abrogate anti-GBM Ab production, and 2) the anti-GBM Ab, eluted from the diseased kidneys, reacted only with native GBM, but not with pCol(28-40). Confocal microscopy and immunoprecipitation further demonstrated that the eluted anti-GBM Ab recognized conformational B cell epitope(s) of multiple native GBM proteins. We conclude that autoantibody response to diverse native GBM Ags was induced by a single nephritogenic T cell epitope. Thus, anti-GBM Ab may actually be a consequence of T cell-mediated glomerulonephritis.

Immunodominant epitopes of α3(IV)NC1 induce autoimmune glomerulonephritis in rats

BACKGROUND

The major Goodpasture antibody binding epitopes have been localized to the amino-terminal third of the noncollagenous domain (NC1) of the alpha3 chain of type IV collagen [alpha3(IV)NC1]. The present study determined whether the same epitopes induce glomerulonephritis in rats.

METHODS

We immunized Wistar Kyoto (WKY) rats with human alpha3(IV)/alpha1(IV)NC1 chimeric proteins or full-length recombinant alpha3(IV)NC1 (alpha3732). Chimeric protein constructs were thirds of alpha3(IV)NC1 (CP333) replaced by corresponding sequences of homologous nonreactive alpha1(IV)NC1 (CP111). All chimeric proteins contained 30 amino acids of type X collagen at the amino terminus except alpha3732. Two other constructs, T195 EA (EA) and T194 EB (EB), were entirely alpha1(IV)NC1, except for antibody-immunodominant amino acids from the first and second thirds of alpha3(IV)NC1.

RESULTS

Construct immunized animals developed specific antibody responses to recombinant proteins and native human, bovine and rat NC1. CP311 immunized rats, as well as alpha3732 rats, had glomerular IgG, fibrin, and glomerulonephritis with proteinuria by 3 weeks. CP331 produced more severe disease, comparable to positive controls. CP111 produced no disease. EA, but not EB, induced severe glomerulonephritis. Half-dose each of EA plus EB induced disease identical to full-dose EA alone.

CONCLUSION

The amino third of alpha3(IV)NC1 which contains the major epitope for Goodpasture antibody binding, also induces glomerulonephritis in rats. The middle third of alpha3(IV)NC1 does not induce glomerulonephritis but appears to enhance disease with the amino terminal third. Finally, the presence of the collagen X leader sequence appears to convey greater nephritogenicity. These studies suggest that not only the nephritogenic epitope itself, but flanking sequences and the conformational context of the nephritogenic epitope may influence its ability to cause glomerulonephritis.

Identification of a clinically relevant immunodominant region of collagen IV in Goodpasture disease

BACKGROUND

The characteristic feature of Goodpasture disease is the occurrence of an autoantibody response to the noncollagenous domain of the alpha3 chain of type IV collagen [alpha3(IV)NC1] in the alveolar and glomerular basement membrane. These antibodies are associated with the development of a rapidly progressive glomerulonephritis, with or without lung hemorrhage, whereas autoantibodies specific for the other alpha chains of the heterotrimeric type IV collagen probably do not cause disease. In this study, we have investigated whether differences in fine specificity of autoimmune recognition of the alpha3(IV)NC1 correlate with clinical outcome.

METHODS

For mapping of antibody binding to type IV collagen, chimeric collagen constructs were generated in which parts of the alpha3(IV)NC1 domain were replaced by the corresponding sequences of homologous nonreactive alpha1(IV). The different recombinant collagen chimeras allowed the analysis of antibody specificities in 77 sera from well-documented patients.

RESULTS

One construct that harbors the aminoterminal third of the alpha3(IV)NC1 was recognized by all sera, indicating that it represents the dominant target of the B-cell response in Goodpasture disease. Seventy percent of the samples recognized other parts of the molecule as well. However, only reactivity to the N-terminus of the alpha3(IV)NC1 correlated with prognosis, that is, kidney survival after six months of follow-up.

CONCLUSION

The results indicate the crucial importance of antibody recognition of this particular domain for the pathogenesis of Goodpasture disease, thereby opening new avenues for the development of better diagnostic and therapeutic procedures.

Pulmonary hemorrhage and antiglomerular basement membrane antibody-mediated glomerulonephritis after exposure to smoked cocaine (crack): a case report and review of the literature

A case of Goodpasture's syndrome with a negative immunofluorescence examination of the lung biopsy in a 32-year-old man is described. The patient was a 40 cigarettes per day smoker, who had been smoking cocaine (crack) up to 3 weeks before hospital admission. He developed a diffuse alveolar hemorrhage with extremely acute respiratory distress, followed by renal failure with anuria. Transjugular renal biopsy, immunofluorescence and serum antiglomerular basement membrane antibody titer studies confirmed the diagnosis of Goodpasture's syndrome without linear immunoglobulin G deposits as determined by immunofluorescence examination of the alveolar basement membranes. The case illustrates the potentially complex interrelations between an autoimmune disease and exposure to substances with possible antigenic properties, besides the imperative necessity for an early, accurate diagnosis and treatment for the potential for threatening life. Moreover, the association of Goodpasture's syndrome with crack has not been previously reported.

Long-term clinical experience with continuous ambulatory peritoneal dialysis: access-related problems

Patients with end-stage renal failure can be treated with peritoneal dialysis, which is based on the capacity of the peritoneum to exchange fluid and metabolic products. To achieve this, dialysis fluid has to be instilled in the abdominal cavity through a permanent percutaneous access device. Apart from the advantages of peritoneal dialysis, severe problems are related to the access device. In this study, catheter-related morbidity and mortality are described, as found in the patient population from the University Hospital, Nijmegen, The Netherlands. The overall rates of exit-site infections and peritonitis are respectively 0.80 and 1.36 infection episodes per patient-year. Furthermore, it appeared that exit-site infections and peritonitis are the main reasons for discontinuation of dialysis and removal of the catheter. A correlation between the occurrence of peritonitis and exit-site infections was found. Also, the efficacy of the antibiotic treatment necessary to control these infectious complications is described. It is concluded that the design and the materials used to manufacture the currently used access device are the main reason for the existing morbidity in peritoneal dialysis. Therefore, more efforts should be undertaken to improve the access device, in which the design and the material used are critically considered.

Goodpasture's epitope in development of experimental autoimmune glomerulonephritis in rats

The Goodpasture's epitope (GP) has recently been localized to the last 36 AA of the non-collagenous (NCl) domain of the alpha 3 chain of type IV collagen [alpha 3(IV)]. Since alpha 3(IV) induces glomerulonephritis (GN) in rats and rabbits, the purpose of the present study was to determine if the GP epitope itself could induce GN. We immunized rats with synthetic peptides of GP epitope, 36-mer, alone or as protein conjugates. Rats immunized with bovine GBM served as positive controls. Peptide immunized rats developed high titer antibodies to peptides, but only unconjugated 36-mer induced antibody against human and bovine GBM, but not to rat GBM. Acidic residues and the full length 36-mer were important in production of GBM reactive antibodies. Positive controls developed antibody to GBM without reactivity against 36-mer, had IgG and fibrin on the basement membrane, GN and proteinuria. Kidney eluted antibody was reactive with rat, bovine, and human GBM but not 36-mer. GN rat lymphocytes underwent blast transformation to GBM but not peptide, and peptide immunized animals responded only to the respective peptides. None of the animals immunized with GP peptide epitope, despite the development of anti-peptide antibodies or anti-GBM antibodies, developed any in vivo fixation of antibody to the GBM, abnormal proteinuria, or GN. The present study shows that the GP epitope is sufficient to induce an immune response to the epitope, but it is not sufficient to induce GN. This demonstrates that other factors or epitopes are important in the pathogenicity of GBM induced GN in this model. These remain to be delineated.

Identification of antigenic epitopes in type IV collagen by use of synthetic peptides

Peptides representing potential antigenic regions of the NC-1 and 7-S domains of the human alpha 1 and alpha 2, and bovine alpha 3 chains of type IV collagen were synthesized either chemically or by the recombinant DNA technique and tested by ELISA using antibodies raised in rabbits against the whole type IV collagen or the NC-1 domain. Sera from patients with Goodpasture syndrome (GP) or with acute poststreptococcal glomerulonephritis (APSGN) were also tested. The location of antigenic determinants was predicted from the primary and secondary structure of the chains, that is, aromaticity, hydrophilicity and presence of beta-turns. All synthetic peptides reacted with the antiserum to type IV collagen (anti-Col IV). Whereas all peptides arising from the NC-1 domain reacted with anti-NC-1, intact 7-S or peptides of the alpha 1 or alpha 2 chain of the 7-S domain did not react. However intact 7-S reacted with anti-Col IV. Two synthetic peptides from the NC-1 domain of alpha 1, (a.a. 71-90 and a.a. 176-190), one from the alpha 2 (a.a. 70-83) and four from the alpha 3 chain (a.a. 72-89, a.a. 104-117, a.a. 133-145, a.a. 185-203) reacted with anti-NC-1 and anti-COL IV. The above peptides, except alpha 3 (72-89) and alpha 3 (185-203), were tested and found to be reactive with sera from patients with GP.(ABSTRACT TRUNCATED AT 250 WORDS)