New horizons in renal vasculitis

Rare renal pathologic manifestation of antineutrophil cytoplasmic antibodies associated vasculitis as suppurative interstitial nephritis: A case report and review of the literature

A 69-year old male patient attended our clinic with fatigue, fever, anuria, nephritic syndrome and severe renal failure. Kidney biopsy showed pauci-immune crescentic glomerulonephritis with an unusual association of suppurative interstitial nephritis. Though most patients with renal involvement linked to antineutrophil cytoplasmic antibodies associated vasculitis (AAV) have pauci-immune glomerulonephritis, only a few patients were identified to have atypical renal pathology. In most cases, mononuclear tubulointerstitial infiltrate may be a feature of AAV, suppurative interstitial nephritis is very rare. In the literature, we found only one case reported associated with suppurative interstitial nephritis without glomerulonephritis who later developed classic pauci-immune necrotizing glomerulonephritis. Here, we report a case diagnosed as AAV, presenting with pauci-immune crescentic glomerulonephritis and suppurative interstitial nephritis. It is not clear whether suppurative interstitial nephritis is a severe disease variant in AAV-associated renal disease. As described in the first case the lack of improvement in renal functions in spite of intense immunosuppressive treatment leads to the conclusion that suppurative interstitial nephritis is a marker of poor prognosis.

Proteinase-3 mRNA expressed by glomerular epithelial cells correlates with crescent formation in Wegener's granulomatosis

BACKGROUND

Wegener's granulomatosis (WG) is characterized by systemic vasculitis with crescentic glomerulonephritis (CGN) and circulating autoantibodies directed against neutrophil cytoplasmic antigens (ANCA). Proteinase 3 (PR-3), a neutral serine proteinase in neutrophils implicated in the growth control of myeloid cells, has been identified as the target antigen for ANCA in WG. Since the kidneys are frequently involved in WG, we studied the in situ expression of PR-3 by renal parenchymal cells.

METHODS

We assessed the expression of PR-3 in kidney biopsies of 15 patients with WG by immunohistochemistry (IHC) and in situ hybridization (ISH). Normal kidney tissue served as the control.

RESULTS

We detected PR-3 mRNA and PR-3 protein in distal tubular epithelial cells (TECs) and glomerular epithelial cells (GECs) in normal kidney tissue and in CGN. Furthermore, a strong glomerular PR-3mRNA expression restricted to the site of cellular crescents was detected in patients with WG. The analysis of 144 glomeruli with cellular or sclerotic crescents revealed a positive correlation of glomerular PR-3mRNA expression with the percentage of cellular crescents per glomerulus. The capability of human TECs and GECs to synthesize PR-3 was confirmed by Northern blot and ISH on cultured cells.

CONCLUSION

These data provide evidence that nonhematopoetic renal parenchymal cells express PR-3 and that glomerular expression of PR-3 is associated with crescent formation in WG. Our findings suggest that renal parenchymal cells may directly be involved in the pathogenesis of CGN in WG.

Long-term clinical course and histopathologic scoring in acute crescentic glomerulonephritis

If nontreated or misdiagnosed, acute crescentic glomerulonephritis, clinically defined as rapidly progressive glomerulonephritis (RPGN), may led to end-stage renal failure (ESRD) within a short time. Histologically, it is characterized by accumulation of inflammatory cells in combination with proliferation of epithelial cells in the glomerulus. According to the proposed immunopathogenic classification by Couser (7), predominantly the immunopathogenic type III without immune deposits often represents the renal manifestation of a systemic vasculitic disease, for example, polyarteriitis or Wegener's granulomatosis. Having investigated 75 patients with acute crescentic glomerulonephritis in respect to their long-term results, we conclude that an early histopathologic diagnosis by using an activity and chronicity score system may not only be a predictor for renal prognosis but also be a valid supposition for differentiated immunosuppressive therapy in supplement to the clinical data on renal function. A therapeutic advantage of a plasmapheresis therapy additionally to the immunosuppressive therapy could not be proven.

The diagnostic and prognostic significance of ANCA

Antineutrophil cytoplasmic antibodies (ANCA) constitute a family of auto-antibodies directed against various components of the neutrophil cytoplasm. Their identification and association with vasculitis and rapidly progressive glomerulonephritis has led to considering these diseases as possible autoimmune disorders. In addition, ANCAs constitute a diagnostic tool and a guideline for therapy during follow-up. Originally identified by Davies et al. in 1982 in 8 patients who had necrotizing glomerulonephritis but no immune deposits or systemic vasculitis (1), ANCA are now regarded as a serological marker for active pauci-immune necrotizing and crescentic glomerulonephritis, either in their renal-limited form or associated with systemic vasculitis such as Wegener's granulomatosis (WG), microscopic polyangiitis (mPA), and Churg-Strauss syndrome (CSS) (2-9). The usefulness of ANCA detection for the diagnosis of these forms of vasculitis is now established but its usefulness on follow-up remains disputed (10-13). Two major ANCA antigens have already been identified. Proteinase 3 (PR3) in a serine protease of 29 kDa initially identified by Kao and producing a cytoplasmic staining pattern termed cANCA by indirect immunofluorescence (IIF) (14,15). Myeloperoxidase (MPO) is another myeloid lysosomal enzyme producing an artefactual perinuclear staining of ethanol-fixed neutrophils termed pANCA (2,16). Both are localized in the azurophilic granules of neutrophils and monocytes, are translocated to the cell surface during cell activation (17), and are able to interact directly with ANCA. Despite this common location, MPO and PR3 are associated with a broad spectrum of clinical conditions.

Long-term clinical course in acute crescentic glomerulonephritis

If non-treated or misdiagnosed, acute crescentic glomerulonephritis, clinically defined as rapidly progressive glomerulonephritis (RPGN), may lead to end-stage renal failure (ESRD) within a short time. Histologically, it is characterized by accumulation of inflammatory cells in combination with proliferation of epithelial cells in the glomerulus. According to the proposed immunopathogenic classification by Couser [7], predominantly the immunopathogenic type III without immune deposits often represents the renal manifestation of a systemic vasculitic disease, e.g. polyarteriitis or Wegener's granulomatosis. Having investigated 75 patients with acute crescentic glomerulonephritis for long-term results, we concluded that early histopathologic diagnosis by using an activity and chronicity score system may be not only a predictor for renal prognosis but also a valid supposition for differentiated immunosuppressive therapy in supplement to the clinical data on renal function. The therapeutic advantage of plasmapheresis therapy in addition to immunosuppressive therapy could not be proven.

Mortality in the rheumatic diseases

OBJECTIVE

To review mortality data in published studies of various rheumatic diseases.

METHODS

A MEDLINE search of the literature on the rheumatic diseases, including osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, scleroderma, polymyositis, and vasculitis.

RESULTS

Mortality rates higher than expected have been reported in most rheumatic conditions, considerably higher for inflammatory rheumatic diseases. The mortality rates in patients with systemic lupus erythematosus, scleroderma, polymyositis, and vasculitis are often comparable to mortality rates seen in patients with neoplastic or cardiovascular diseases, although the causes of death often are not identified as the rheumatic disease.

CONCLUSION

Mortality has been found to be predicted in most instances by more severe clinical status, and therefore death should not be considered as "unrelated" to the rheumatic disease. These observations may have important implications for clinical care and health policies regarding patients with rheumatic diseases.

Distribution of the granulocyte serine proteinases proteinase 3 and elastase in human glomerulonephritis

The serine proteinases proteinase 3 (PR3) and elastase are target antigens of antineutrophil cytoplasmic autoantibodies (ANCAs), which are found in various systemic vasculitides with rapidly progressive glomerulonephritis (RPGN). The expression of both proteinases was studied immunohistologically (avidin-biotin complex method) with murine monoclonal antibodies against PR3 (WGM2) and elastase (NP 57) in 122 human renal biopsy specimens to investigate their role in mediating renal damage. Expression of PR3 predominated in ANCA-associated RPGN and was independent of the serologic ANCA pattern (c-/p-ANCA). The PR3 staining pattern was patchy and not always related to distint granulocytes due to antigen spreading by disintegrating cells. It was found in crescentic glomeruli and the interstitum of ANCA-positive RPGN. In contrast, glomerular and interstitial elastase staining pattern was much more granulocyte related and was even found in noncrescentic glomeruli in c-ANCA- and p-ANCA-positive pauci-immune RPGN. Endothelial cell and glomerular basement membrane-bound PR3 or elastase expression were not observed. A faint glomerular PR3/elastase expression was seen in Goodpasture's syndrome and within the interstitium in crescentic mesangioproliferative glomerulonephritis (granulocyte related). Both serine proteinases were found in the glomeruli in ANCA-negative acute postinfectious glomerulonephritis. In conclusion, this study provides evidence, for the first time, for the implication of the granulocyte serine proteinases PR3 and elastase in mediating pauci-immune ANCA-positive RPGN and different forms of proliferative glomerulonephritis. The expression of ANCA antigens in ANCA-negative glomerulonephritis suggests that this finding is a marker of neutrophil activation.(ABSTRACT TRUNCATED AT 250 WORDS)

A novel class of autoantigens of anti-neutrophil cytoplasmic antibodies in necrotizing and crescentic glomerulonephritis: the lysosomal membrane glycoprotein h-lamp-2 in neutrophil granulocytes and a related membrane protein in glomerular endothelial cells

Necrotizing and crescentic glomerulonephritis (NCGN) is frequently associated with circulating antineutrophil cytoplasmic autoantibodies (ANCA). It is established that ANCA are specific for soluble enzymes of granules of polymorphonuclear neutrophil granulocytes (PMN), such as myeloperoxidase (MPO) or protease 3 (PR3). The purpose of this study was to identify membrane proteins of PMNs, and/or glomerular cells, as additional autoantigenic ANCA targets. When membrane protein fractions were prepared from PMNs and isolated human glomeruli, and immunoblotted with ANCA sera of NCGN patients, two bands with apparent molecular masses of 170 and 80-110 kD (gp170/80-110) were labeled in PMNs, and a 130-kD glycoprotein (gp130) in glomeruli. Gp130 was purified, and monoclonal and rabbit antibodies (Abs) were produced which showed the same double specificity as the patient's ANCA. Using these probes, evidence was provided that gp170/80-110 is identical with human lysosomal-associated membrane protein 2 (h-lamp-2), because both proteins were immunologically cross-reactive and screening of a cDNA expression library from human promyelocytic leukemia cells with anti-gp130 Ab yielded a clone derived from h-lamp-2. Gp170/80-110 was localized primarily in granule membranes of resting PMNs, and was translocated to the cell surfaces by activation with FMLP. By contrast, gp130 was localized in the surface membranes of endothelial cells of human glomerular and renal interstitial capillaries, rather than in lysosomes, as found for h-lamp-2. Potential clinical relevance of autoantibodies to gp170/80-110 and gp130 was assessed in a preliminary trial, in which ANCA sera of patients (n = 16) with NCGN were probed with purified or recombinant antigens. Specific reactivity was detected in approximately 90% of cases with active phases of NCGN, and frequently also in combination with autoantibodies specific for PR3 or MPO. Collectively, these data provide evidence that h-lamp-2 in PMNs and a different, structurally related 130-kD membrane protein on the cell surface of renal microvascular endothelial cells are autoantigenic targets for ANCA in patients with active NCGN.

Rapidly progressive glomerulonephritis (RPGN): is there still an "idiopathic" subgroup?

In order to clarify if "idiopathic" RPGN still exists as a distinct entity we reviewed 41 patients with histological picture of diffuse crescentic GN (60% of crescents) and no clinical evidence of systemic disease. According to the presence or absence of intraglomerular necrotizing lesions we subdivided the patients into two different morphological groups: Group I (25 pts) with necrotizing GN and massive periglomerular infiltrates; Group II (16 pts) with intra-extracapillary proliferation and no interstitial infiltrates. Our data suggest that "idiopathic" RPGN does not exist as a distinct entity, but is an expression either of renal limited vasculitis or crescentic GN complicating primary proliferative GN.

Characterization of anti-myeloperoxidase antibodies in vasculitis

Anti-myeloperoxidase (MPO) antibodies are frequently encountered in patients with vasculitis. Using a competitive inhibition ELISA test and immunoblotting, we suggest that anti-MPO antibodies might represent a heterogenous group of auto-antibodies directed against different conformational epitopes of MPO molecule.