Histological beta-2-microglobulin amyloidosis 10 years after a successful renal transplantation

Beta-2 microglobulin in ESRD: an in-depth review

Beta-2 microglobulin is the most widely studied low-molecular-weight protein in end-stage renal disease. It is known to cause dialysis-related amyloidosis (DRA), by virtue of its retention when renal function fails, its deposition in tissues, its aggregation into fibrils, and its ability to become glycosylated. The onset of DRA may be protracted by the use of noncellulosic membranes, especially when high-volume hemodiafiltration is used in the treatment of renal failure. Adsorptive methods have been developed to improve the removal of beta-2 microglobulin. There seems to be a relative risk reduction in mortality when patients are treated with dialysis membranes that have a higher clearance of beta-2 microglobulin.

Dialysis-related amyloidosis after renal transplantation

There is no effective therapy for dialysis-related amyloidosis (DRA). The restoration of renal function with a functional graft seems the most reasonable therapy for this disturbing disease. Although there are not many prospective series on the efficacy of renal transplantation for DRA, all the studies agree that most of the patients experienced a significantly clinical improvement of the articular symptoms after a successful renal transplantation. Nevertheless, radiologic (bone cysts) and histologic lesions did not disappear after long-term follow-up.

Synovial inflammatory cells captured 131I-beta 2-microglobulin in patients with dialysis related amyloidosis

Dialysis related amyloidosis (DRA) is a major complication of long term hemodialysis therapy. It is well recognized that scintigraphic study using radioisotope-labeled beta 2-microglobulin (beta 2M) as a tracer is a sensitive and specific technique to diagnose DRA non-invasively. The aim of this study is to clarify the mechanism of 131I-beta 2M accumulation around the amyloid tissue. Three dialysis patients with carpal tunnel syndromes were examined for consecutive 131I-beta 2M scintigraphies every 24 hours for 3 days till the carpal tunnel synovectomy. Removed synovial tissues were processed for histological study. The scintigraphic study demonstrated tracer accumulations in the joints involved with DRA and the intensity increased in a time dependent fashion. Microscopic observations revealed many inflammatory cells presenting CD68-monocytes/macrophages antigen infiltrated into the synovial tissues. 131I-beta 2M was evident in the cytoplasm of the infiltrating cells, while no radioactivity was detected above background in the amyloid tissues. In conclusion, the tracer accumulations observed in the 131I-beta 2M scintigraphic studies were the consequence of circulating beta 2M assimilated by the infiltrating monocytes/macrophages. Thus, the undetermined elimination pathway of circulating beta 2M in the dialysis patients was identified as the storage pool in those inflammatory cells. The inflammatory change may play a crucial role in the local progression of DRA through the accumulation of circulating beta 2M around the established amyloid tissues.

Histological prevalence of beta 2-microglobulin amyloidosis in hemodialysis: a prospective post-mortem study

The histological prevalence of beta-2 microglobulin amyloidosis (A beta 2m) was evaluated in a prospective study of joint samples obtained at autopsy in 54 patients on hemodialysis (HD) for 2 to 163 (median 47) months, aged 20 to 80 (median 63) years at HD onset. Carpal tunnel syndrome surgery or radiological signs of A beta 2m were present in 2 and 4% of them, respectively. A control group of 34 patients without end-stage renal disease, autopsied during the same period was used as a reference. The 153 sampled joints (1 to 8, median 2 per patient) were sternoclavicular joints (N = 77), shoulders (N = 35), knees (N = 28), others (N = 13). A beta 2m was diagnosed (positive Congo red with typical birefringence and positive immunostaining of deposits for beta 2m) in 26 of 54 (48%) patients. Prevalence reached respectively 21%, 33%, 50%, 90% and 100% within two years, after 2 to 4 years, 4 to 7 years, 7 to 13 years and more than 13 years HD. The calculated sensitivity of the various joints for A beta 2m detection is significantly higher (P < 0.03) for sternoclavicular joints (97%) and knees (91%) than for shoulders (57%). Multivariate stepwise logistic regression with discriminant analysis identified both HD duration (P = 0.0008) and age at HD onset (P = 0.0093) but not diabetic nephropathy (P = 0.23) or gender (P = 0.25) as independent risk factors for A beta 2m. The probability of joint A beta 2m was quantitated as a function of age and HD duration. In conclusion, A beta 2m may be observed in the large joints early after HD onset. Overall prevalence reaches 48% of the patients on HD for a median of 47 months. It is much higher than that reported on the basis of clinical or radiological evidence. The sternoclavicular and knee joints are more frequently (P < 0.03) involved than the shoulder. The easily accessible sternoclavicular joint therefore appears to be the best site for the early detection of A beta 2m. Both HD duration and age at HD onset, but not diabetic nephropathy, are independent risk factors for A beta 2m.