IgG4-related disease and hypertrophic pachymeningitis

Hypertrophic pachymeningitis (HP) is an inflammatory condition in which the dura mater of the cranium or spine becomes thickened, leading to symptoms that result from mass effect, nerve compression, or vascular compromise. The differential diagnosis of HP includes immune-mediated conditions such as rheumatoid arthritis and vasculitis, malignancies, and infections. Many times, no diagnosis is reached; in such cases, the disease has been described as idiopathic HP. IgG4-related disease (IgG4-RD) is a recently described inflammatory condition known to cause tumefactive lesions at myriad anatomical locations. Both IgG4-RD and idiopathic HP share similar demographics, histopathology, and natural history. We hypothesized that IgG4-RD is a common cause of idiopathic HP.To investigate this hypothesis, we identified all pathology specimens diagnosed as noninfectious HP during 25 years at our institution. Fourteen cases had stained slides and paraffin blocks to permit review of the original hematoxylin and eosin stained slides as well as immunostaining of cell blocks. Recently published consensus guidelines describing characteristic histopathology and the necessary quantity of IgG4+ plasma cell infiltrate were used to diagnose IgG4-RD.Four cases (66.6%) that had been regarded previously as representing idiopathic HP were diagnosed as IgG4-RD; of all the reviewed cases, IgG4-RD represented 29% of cases. Of the remaining cases, 3 cases were associated with granulomatosis with polyangiitis (GPA), 2 with lymphoma, and 1 each with rheumatoid arthritis, giant cell arteritis, and sarcoidosis. Two of the cases could not be diagnosed more precisely and were classified as undifferentiated HP. Clinical history, serologic tests, cerebrospinal fluid studies, and radiology alone could not identify the cause of HP. Rather, biopsy with histopathology and immunostaining was necessary to reach an accurate diagnosis. Significant IgG4+ plasma cell infiltrates were observed in rheumatoid arthritis, granulomatosis with polyangiitis, and lymphoma, underscoring the importance of histopathology in making the diagnosis of IgG4-RD.This case series demonstrates that IgG4-RD may be the most common etiology of noninfectious HP and highlights the necessity of biopsy for accurate diagnosis.

Generalized cytomegalic inclusion-body disease associated with pneumocystis pneumonia in adults. A report of three cases. with Wegener's granulomatosis. thrombotic purpura, and Hodgkin's disease as predisposing conditions

Three cases of generalized cytomegalic inclusion-body disease (salivary virus disease) in adults are reported, bringing the number of published cases up to 34. The infection is very rare in adults although well known in infants. As is often found in infants with this disease, pneumonia due to Pneumocystis carinii was also present in each case. The first patient had Wegener's granulomatosis, which presented with acute otitis media: a review of histological material obtained at mastoidectomy eight weeks before death showed that inclusion-body cytomegaly was already present then. Various antibiotics and prednisolone were given, and the lesions in the respiratory organs and the arteritis healed to a considerable extent. Renal failure, however, was progressive and led to death. The second patient had thrombotic purpura and died after a few weeks' illness, during which oxytetracycline and hydrocortisone were given. Congenital absence of the spleen was found at laparotomy, which was performed with the object of doing a splenectomy. Focal cryptococcal pneumonia was present post mortem: six years before death a solitary cryptococcal granuloma of one lung had been treated by lobectomy. The third patient had had Hodgkin's disease for 18 years. During the first 12 years the disease had the characteristics of the so-called indolent form ("Hodgkin's paragranuloma") and it then passed into the typical form. Deep x-ray therapy and cytotoxic drugs were used during the course of the disease at various times, and streptomycin and tuberculostatic drugs were given because of intercurrent tuberculous meningitis which developed three months before death. In all three cases it seems likely that the underlying disease, or the drugs used in its treatment, predisposed to cytomegalic inclusion-body disease and concomitant pneumocystis pneumonia by lowering the patients' resistance. Just as some unusual types of fungal and bacterial infections have become less rare since the introduction of certain drugs, including antibiotics and steroids, it is possible that cytomegalic inclusion-body disease and pneumocystis infection may also be met with oftener in adults, perhaps particularly as a complication of the use of these drugs in the treatment of diseases which are specially liable to interfere with the body's defences.

Genetics of ANCA-associated vasculitis: role in pathogenesis, classification and management

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) comprises granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA), that share features of pauci-immune small-vessel vasculitis and the positivity of ANCA targeting proteinase-3 (PR3-ANCA) or myeloperoxidase (MPO-ANCA). AAV syndromes are rare, complex diseases and their aetio-pathogenesis is mainly driven by the interaction between environmental and genetic factors. In patients with GPA and MPA, the genetic associations are stronger with ANCA specificity (PR3- versus MPO-ANCA) than with the clinical diagnosis, which, in keeping with the known clinical and prognostic differences between PR3-ANCA-positive and MPO-ANCA-positive patients, supports an ANCA-based re-classification of these disorders. EGPA is also made up of genetically distinct subsets, which can be stratified on ANCA-status (MPO ANCA-positive versus ANCA-negative); these subsets differ in clinical phenotype and possibly in their response to treatment. Interestingly, MPO-ANCA-positive patients with either MPA or EGPA have overlapping genetic determinants, thus strengthening the concept that this EGPA subset is closely related to the other AAV syndromes. The genetics of AAV provides us with essential information to understand its varied phenotype. This Review discusses the main findings of genetic association studies in AAV, their pathogenic implications and their potential effect on classification, management and prognosis.

Evaluation of a new fluorescent-enzyme immuno-assay for diagnosis and follow-up of ANCA-associated vasculitis

In this study we have evaluated a new, fully automated fluorescent-enzyme immuno-assay (FEIA) for detection and quantification of anti-PR3 and anti-MPO ANCA in diagnosis and follow-up of ANCA-associated small vessel vasculitis (AAV). PR3- and MPO-ANCA were determined by FEIA technology in (1) sera of 87 consecutive patients with biopsy-proven, pauci-immune necrotizing crescentic glomerulonephritis (NCGN) and 72 controls; (2) 120 sera (60 patients with Wegener's granulomatosis and 60 controls) that were previously used in a multicentre comparison of direct and capture ELISAs for PR3-ANCA; (3) in samples preceding relapse in 23 PR3-AAV patients with and 23 matched PR3-AAV patients without relapse for prediction of relapses. PR3- and/or MPO-ANCA detection in pauci-immune NCGN by FEIA revealed an overall sensitivity of 82.8%. The FEIA specificity was 96% and 100% for PR3- and MPO-ANCA, respectively. The overall sensitivity of MPO- and PR3-ANCA could be increased to 88.5% by lowering the cut-off values without affecting the specificity (ROC-curve analysis), which is similar to a multistep ANCA procedure that combines indirect immunofluorescence with direct and capture ELISAs. The sensitivity for Wegener's granulomatosis (WG) of the PR3-ANCA FEIA (60%) was more comparable to direct ELISAs (64%) than to capture ELISAs (74%). A rise of 100% in ANCA level as measured by FEIA appeared optimal (ROC-curve) for prediction of relapses and such a rise was observed in 26 patients. In 18 of these 26 patients the rise was followed by a relapse (PPV 69%), whereas in 15 of the 20 patients without a rise no relapse was observed (NPV 75%). In conclusion, detection of PR3- and MPO-ANCA by FEIA has excellent performance in terms of diagnosis of AAV patients. Furthermore, detection of rises in PR3-ANCA by FEIA for prediction of relapses gives results comparable to other techniques.

Recombinant human proteinase 3, the Wegener's autoantigen, expressed in HMC-1 cells is enzymatically active and recognized by c-ANCA

We developed a stable expression system for conformationally intact recombinant human PR3 (rPR3) using the human mast cell line HMC-1. Like in U937 cells, the rPR3 is processed from a 34 kDa precursor to the 29 kDa mature form, primarily as the result of oligosaccharide trimming. The rPR3 binds [3H]DFP and hydrolyzes the substrate N-methoxysuccinyl-Ala-Ala-Pro-Val-pNA. The enzymatic activity is inhibited by greater than 95% by alpha 1-PI. The rPR3 and the enzymatically inactive mutant rPR3-S176A are both packaged in granules. Thus, proteolytic autoprocessing is not required for PR3's targeting to granules. This rPR3 is the first to be recognized by most c-ANCA from WG patients and all anti-PR3 ANCA that were detected by standard anti-PR3 specific ELISA. This expression system for rPR3 represents a versatile tool for the analysis of its intracellular processing, structure-function relationships and interaction with autoantibodies.

Wegener's granulomatosis

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Compared action of neutrophil proteinase 3 and elastase on model substrates. Favorable effect of S'-P' interactions on proteinase 3 catalysts

Neutrophil proteinase 3 (Pr3) and elastase (NE) may cause lung tissue destruction in emphysema and cystic fibrosis. These serine proteinases have similar P(1) specificities. We have compared their catalytic activity using acyl-tetrapeptide-p-nitroanilides, which occupy the S(5)-S'(1) subsites of their substrate binding site, and intramolecularly quenched fluorogenic heptapeptides, which bind at S(5)-S'(4). Most p-nitroanilide substrates are turned over slowly by Pr3 as compared with NE. These differences disappear with the fluorogenic heptapeptides, some of which are hydrolyzed even faster by Pr3 than by NE. Elongation of substrates strongly increases the catalytic efficiency of Pr3, whereas it has little effect on NE catalysis. These different sensitivities to S'-P' interactions show that Pr3 and NE are not interchangeable enzymes despite their similar P(1) specificity.

Glomerular vascular cell adhesion molecule-1 expression in renal vasculitis

AIMS

To study the expression of cell adhesion molecules in the renal biopsy specimens of patients with systemic vasculitis and Henoch-Schönlein purpura (HSP); to correlate this with the severity of glomerular inflammation.

METHODS

Renal biopsy specimens obtained from eight patients with untreated systemic vasculitis (four with Wegener's granulomatosis and four with microscopic polyarteritis), eight with HSP and nine controls (four with normal histopathology and five with thin glomerular basement membrane disease) were stained using the alkaline phosphatase anti-alkaline phosphatase method with monoclonal antibodies directed against intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin.

RESULTS

Biopsy specimens of normal kidneys expressed ICAM-1 in glomerular endocapillary cells, Bowman's capsule epithelium, interstitial cells and interstitial vascular endothelium, and VCAM-1 in Bowman's capsule epithelium, proximal tubular epithelium and interstitial vascular endothelium. No staining with antibody directed against E-selectin was seen in any of the biopsy specimens. Biopsy specimens of patients with a vasculitic glomerulonephritis (segmental necrotising glomerulonephritis) expressed VCAM-1 in glomerular endocapillary cells (four of eight patients with systemic vasculitis; two of eight patients with HSP). In patients with a systemic vasculitis glomerular VCAM-1 expression was associated with a more severe renal lesoin (44, 50, 60, and 65% of glomeruli involved) than in those not showing glomerular VCAM-1 expression (3, 3, 11, and 39% of glomeruli involved).

CONCLUSION

Expression of VCAM-1 by glomerular endocapillary cells in renal biopsy specimens raises the possibility that recruitment of VLA-4 bearing leucocytes may contribute to glomerular injury in Wegener's granulomatosis and microscopic polyarteritis.

ANCA associated vasculitis

Vasculitis is characterized by inflammation of the vascular wall. It reaches vessels of different sizes and locations, conditioning multisystem and complex manifestations that require a holistic approach. Antineutrophil cytoplasmic antibody-associated vasculitis has an annual incidence rate of 20 per million inhabitants. It is the result of the interaction of infectious, genetic and environmental factors and manifest itself with varied and unspecific symptoms, often reaching the general state, respiratory and renal systems. The combination of clinical, laboratory, imaging and fundamentally histological changes allows the diagnosis and classification of the extent / severity of the disease necessary for the decision of the therapeutics to be taken. Glucocorticoids are generally used; with methotrexate being considered when localized disease and cyclophosphamide, rituximab or azathioprine when generalized disease. A systematized approach can increase survival rates from 12% to 70% over a 5-year span.