Proteomics of beta2-microglobulin amyloid fibrils.

Knowledge on the chemical structure of beta2-microglobulin in natural amyloid fibrils is quite limited because of the difficulty in obtaining tissue samples suitable for biochemical studies. We have reviewed the available information on the chemical modifications and we present new data of beta2-microglobulin extracted from non-osteotendinous tissues. beta2-microglobulin can accumulate in these compartments after long-term haemodialysis but rarely forms amyloid deposits. We confirm that truncation at the N-terminus is an event specific to beta2-microglobulin derived from fibrils but is not observed in the beta2-microglobulin from plasma or from the insoluble non-fibrillar material deposited in the heart and spleen. We also confirm the partial deamidation of Asn 17 and Asn 42, as well as the oxidation of Met 99 in fibrillar beta2-microglobulin. Other previously reported chemical modifications cannot be excluded, but should involve less than 1-2% of the intact molecule.

Light chain deposition disease with renal involvement: clinical characteristics and prognostic factors.

BACKGROUND: Light chain deposition disease (LCDD) is characterized by the tissue deposition of monotypical immunoglobulin light chains (LCs). The aim of this study was to investigate its clinical characteristics and prognostic factors. METHODS: Multicenter study of LCDD with renal and patient survival analyses. RESULTS: Sixty-three cases were studied (age: 58 +/- 14.2; males: 63.5%; kappa/lambda deposition: 68/32%; underlying disorders: multiple myeloma [MM] 65%, lymphoproliferative disorders 3%, idiopathic 32%). Ninety-six percent presented with renal insufficiency (acute, 52%; chronic, 44%), and 84% with proteinuria >1 g/d. During the follow-up, 36 patients reached uremia (incidence rate: 23.7/100 patient-years) and 37 died (17.5/100 patient-years). The factors independently associated with a worse renal prognosis were age (relative risk [RR], 1.05; 95% confidence interval [CI], 1.009 to 1.086) and serum creatinine at presentation (RR, 1.24; 95% CI, 1.02 to 1.5). Those independently associated with a worse patient survival were age (RR, 1.06; 95% CI, 1.03 to 1.1), MM (RR, 2.75; 95% CI, 1.22 to 6.2), and extrarenal LC deposition (RR, 2.24; 95% CI, 1.15 to 4.35). While kappa-LC deposition was more frequently associated with nodular sclerosing glomerulopathy, histological parameters were not predictors of renal/patient prognosis. The survival of the uremic patients undergoing dialysis was similar to that of patients not reaching uremia. CONCLUSION: LCDD is characterized by renal insufficiency with proteinuria and has a severe prognosis. Apart from age, the prognostic factors identified were degree of renal insufficiency at presentation affecting the renal prognosis, underlying hematologic disorder and extrarenal LC deposition affecting the patient prognosis. Dialysis is worth performing in uremic LCDD patients.

Clinical, radiological, and biochemical features of a bilateral buttock amyloidoma emerging after 27 years of hemodialysis.

Deposition of amyloid in the buttock is a rare complication of dialysis related amyloidosis (DRA), but this localization is even rarer in other types of amyloidoses. We report here the clinical, radiological, and biochemical features of a patient who incurred into this complication after 27 years of hemodialysis. Imaging of the amyloid deposition by magnetic resonance imaging (MRI) documents the amyloid infiltration in the muscles of the buttock region and highlights a peculiar feature of amyloid fibrils deposition in the subcutaneous fat. The amyloid deposition is confirmed by biochemical and microscopic analysis of fibrils extracted from a biopsy specimen. Review of literature and the features of this case lead to speculation that the peculiar involvement of the buttock region including muscles and subcutaneous fat in DRA might derive from the propagation of amyloid initially deposited in the hip joint.

Long-term prognosis of diffuse proliferative glomerulonephritis associated with infection in adults.

BACKGROUND: Infection-associated glomerulonephritis is rare in adults and its long-term prognosis is undefined. METHODS: We retrospectively evaluated the clinical course of 50 adults (30 men, 20 women) with infection-associated glomerulonephritis diagnosed in our department from 1979 to 1999. The mean follow-up was 90+/-78 months. Patients were subdivided into two groups: group 1 included those without underlying disease and group 2 included those with severe underlying disease. RESULTS: At presentation, the median age was 54 years, and 33 patients were hypertensive, 31 had nephritic syndrome, eight had nephrotic syndrome and 11 had non-nephrotic proteinuria. Patients in group 2 were significantly older and had a significantly higher proteinuria than patients of group 1. Of the 21 patients in group 2, nine had liver cirrhosis, four cancer, five diabetes, three bronchiectasis, one thalassaemia intermedia, one polymyositis and one had anti-phospholipid antibodies syndrome. At the last follow-up, five patients had died, 21 patients were in complete remission, ten had partial remission, ten had renal insufficiency and three were on chronic dialysis. Multivariate analysis showed that an underlying disease (P=0.04) and interstitial infiltration at biopsy (P=0.036) were predictors of incomplete recovery. A correlation analysis between the year of diagnosis and the clinical/ histological characteristics at presentation showed that age (P=0.05), atypical infections (P=0.01), underlying disease (P=0.01) and interstitial infiltration at biopsy (P=0.02) increased over time, while the number of patients with complete remission significantly decreased (P=0.001). CONCLUSIONS: Infection-associated glomerulonephritis may progress to chronic renal failure in a consistent number of adult hospitalized patients, particularly in those with an underlying disease and when associated with interstitial infiltration at biopsy.