Beta 2-microglobulin and dialysis-related amyloidosis

Dialysis-related amyloidosis is a common complication encountered in patients receiving chronic hemodialysis. beta 2-microglobulin(beta 2-m) constitutes the causative protein of amyloidosis, and its deposition in tissues has been proven to be a primary cause of the onset. However, many other risk factors are also associated including (1) prolonged duration of dialysis, (2) advanced age, (3) dialysate of low purity, and (4) the use of a dialysis membrane with poor biocompatibility. Recently we confirmed that apolipoprotein E is a risk factor for the onset of carpal tunnel syndrome associated with dialysis-related amyloidosis. Dialysis using high-flux membranes and the clinical application of a column that selectively adsorbs beta 2-m are currently being assessed interms of the ability to remove as much beta 2-m from the blood as possible. Drug therapy may also be useful at present in symptomatic treatment; a low dose of adrenocorticosteroids has recently been demonstrated as extremely effective for joint pain associated with beta 2-m amyloid deposits. The long-term use of drugs, however, carries a risk of side effects. As a therapeutic approach to dialysis-related amyloidosis, high-flux dialysis membranes permitting the elimination of beta 2-m with satisfactory biocompatibility have been developed and positive clinical effects have been observed both in the retrospective and prospective studies in the use of high-flux membranes together with a decrease in the serum beta 2-m level. However, there is no evidence yet of the long term reduction of amyloid deposits when the elimination of beta 2-m is maintained using a high-flux membrane.     

Beta 2-microglobulin amyloidosis (AB2M) in patients undergoing long-term hemodialysis. A new type of amyloid

Amyloidosis has been increasingly recognized in association with renal failure and chronic hemodialysis. This report describes three patients who had long-term hemodialysis (between 7-18 years), in whom deposits developed of a new type of amyloid of beta 2-microglobulin origin. Beta 2-microglobulin amyloid (AB2M) was found in multiple organs, i.e., bone, subendocardium, gastrointestinal blood vessels, tongue, and carpal tunnel connective tissue. AB2M displayed characteristic amyloid features on conventional light and polarized microscopic examination after congo red staining. However immunostaining with anti-amyloid A protein, kappa, and lambda antisera were negative. The studied material reacted positively with beta 2-microglobulin antisera, identifying AB2M in all three cases. Ultrastructural study revealed an unusual curvi-linear fibrillar configuration. AB2M appears to be a new subtype of systemic amyloidosis secondary to renal failure and long-term hemodialysis.     

Beta2-microglobulin clearance with super high flux hemodialysis: an ex vivo study

BACKGROUND: Beta2m accumulation induces disease in patients with end-stage renal failure (ESRF). Thus, its removal from patients with ESRF appears desirable. Current dialysis technology, however, has limited effectiveness. AIMS: To measure beta2m clearance with a novel super high flux membrane. DESIGN: Ex vivo experimental study. SETTING: Intensive Care Laboratory of Tertiary institution. SUBJECTS: Six volunteers. MEASUREMENTS AND RESULTS: At a blood flow of 300 ml/min, the clearance of beta2-MG increased from 113.5 +/- 38.5 ml/min with a dialysate flow rate of 200 ml/min to 184.8 +/- 61.1 ml/min with a flow rate of 300 ml/min and 195.0 +/- 60.0 ml/min with a 500 ml/min flow rate. The clearance of albumin was 4.5 ml/min with a dialysate flow rate of 200 ml/min, 5.2 ml/min for a flow rate of 300 ml/min and 5.8 ml/min for a flow rate of 500 ml/min. CONCLUSIONS: High levels of beta2m clearance can be achieved with a super high flux membrane while albumin losses remain limited.     

Beta2-microglobulin removal and plasma albumin levels with high cut-off hemodialysis

PURPOSE: beta2-microglobulin (beta2MG) is pivotal to the pathogenesis of dialysis-related amyloidosis. We compared the effects of high cut-off hemodialysis (HCO-HD) with those of standard high-flux hemodialysis (HF-HD) regarding the concentration and clearance of beta2MG and albumin. DESIGN: We enrolled ten patients with acute renal failure in a double-blind, cross-over, randomized controlled trial. PROCEDURES: Each patient received four hours of HCO-HD (estimated in vivo cutoff 50-60 kDa) and four hours of HF-HD (estimated in vivo cutoff 15-20 kDa) in random order. Statistical methods and outcome measures: As data lacked normal distribution, we used nonparametric statistical analysis. Plasma and dialysate concentrations of beta2MG and albumin were measured at baseline and after four hours of each study treatment. MAIN FINDINGS: We found significantly greater diffusive beta2MG clearances for HCO-HD compared to HF-HD (at the start: 71.8 ml/min vs. 5.1 ml/min; P=0.008 and at the end: 68.8 ml/min vs. 5.7 ml/min; P=0.008). We found a reduction in plasma beta2MG concentrations of -31.6% during HCO-HD compared to an increase by 25.7% during HF-HD; P=0.008. At baseline (HCO-HD: 26.0 g/L vs. HF-HD: 26.5 g/L), and at the end of both treatments, plasma albumin concentrations were comparable (HCO-HD: 25.5 g/L vs. HF-HD: 26.5 g/L; P=0.25). During HCO-HD, albumin clearance was 1.9 ml/min at the start and decreased significantly to 0.8 ml/min at the end; P=0.008. HF-HD had an albumin clearance of 0.01 ml/min. CONCLUSIONS: HCO-HD was more effective in decreasing plasma beta2MG concentrations than standard HF-HD and did not reduce plasma albumin levels. Further studies of HCO-HD in the treatment of dialysis-related beta2MG accumulation appear warranted.     

Beta 2-microglobulin synthesis of mononuclear cells in chronic dialysis patients.

Beta 2 microglobulin (B2M) has been identified as a major component of amyloid deposits. This study was designed to determine whether changes occur in the synthesis of B2M in dialysis patients. Mononuclear cells (MNC) were isolated in peripheral blood from healthy volunteers, patients on hemodialysis (HD) and on continuous ambulatory peritoneal dialysis (CAPD). MNC were cultured in a medium of RPMI 1640 with or without interleukins IL-1, IL-2 or interferon INF-r. B2M in the cultured cells and supernatant was measured by enzyme immunoassay. IL-2 or INF-r stimulated B2M synthesis was significantly lower (25%) in patients on HD than in normal controls regardless of the type of dialysis membranes used, with no change in basal B2M synthesis. No differences were detected between healthy volunteers and CAPD patients. Preincubation of MNC with complement--activating or non-complement--activating membrane had no influence on B2M synthesis. The basal B2M synthesis of MNC significantly increased after a 4-hour HD regardless of the membranes used, and IL-2 and IFN-r stimulated synthesis were both essentially the same before and after HD. It was thus concluded that maximum capacity for B2M synthesis of MNC decreases in hemodialysis patients. This low responsiveness of MNC may be partially the cause for the reduction in cell-mediated immune response in HD patients.     

Clinicopathologic study of changes in prolapsed intervertebral disks.

To study the various factors that might influence the detection of edge neovascularization that is seen in prolapsed intervertebral disks, clinical features of 112 patients were reviewed. Edge neovascularization, which was seen in nearly one half of surgical specimens, was identified more frequently in lumbar disks (61.2%) than in cervical disks (3.8%). Although the characteristic change was more likely to be found in entirely than partially submitted specimens, the difference was not statistically significant. There was a direct relationship between neovascularization and the duration of symptoms. The frequency of finding the specific change increased from 12.5% in patients with disease for less than a month to 82% of patients who had symptoms for 6 months or more. Specific changes in prolapsed disks probably reflect a reparative phenomenon that is influenced by the degree and duration of mechanical forces.     

Beta 2-microglobulin decrease in cerebrospinal fluid from parkinsonian patients

A sandwich enzyme immunoassay (EIA) was established by using purified beta 2-microglobulin (beta 2-MG) as a standard protein and a polyclonal antibody raised against human beta 2-MG. The EIA was applied for the measurement of beta 2-MG levels in human cerebrospinal fluid (CSF) from parkinsonian patients and control patients devoid of neurological diseases. beta 2-MG contents in CSF of the control group and the parkinsonian group were 1.81 +/- 0.11 micrograms/ml CSF and 0.63 +/- 0.09 microgram/ml CSF, respectively. Thus, beta 2-MG content in CSF was reduced in parkinsonian patients to less than 35% of the control value (P less than 0.005). We had previously reported that the activity and content of dopamine beta-hydroxylase (DBH) were decreased in CSF from parkinsonian patients. A significant positive correlation (r = 0.87) was observed between the beta 2-MG content and DBH activity for CSF from 45 patients. These results suggest a probable link between an immunological change and the changes in catecholaminergic neurons in Parkinson's disease.     

Beta2-microglobulin distribution in human normal tissues.

The distribution of beta2-microblobulin in human normal tissues was investigated by the indirect immunofluorescent antibody method. Lymphoid, macrophage and endothelial cells were consistently positive in every organ studied. In addition, only the stratum germinativum of the epidermis, some tracts of the columnar epithelium of the digestive system and some endometrial tubular glands showed a specific fluorescence.     

Visceral organ involvement and extracellular matrix changes in β2-microglobulin amyloidosis – a comparative study with systemic AA and AL amyloidosis

 Patterns of amyloid distribution and extracellular matrix changes in the heart and gastrointestinal tract were compared among β₂-microglobulin (B2M), AA (secondary), and AL (primary and multiple myeloma-associated) amyloidosis cases. B2M amyloid was found to be mainly distributed in the small arterioles, venules, endocardium and muscularis propria of these organs, the deposits characteristically forming subendothelial nodular lesions in the vessels. A marked increase of chondroitin sulfate (CS) was consistently detected in B2M amyloid. Heparan sulfate (HS) also showed an increase in amyloid deposits, but with less reactivity than CS in the small arterioles or venules. Basement membrane structures stained positively for laminin and collagen type IV were replaced by negative amyloid deposits. In the AL cases, the muscularis propria of the gastrointestinal tract was involved in amyloid deposits, as seen for the B2M type, but the vascular amyloid deposits were localized in the media and adventitia of larger vessels. Immunoreactivity for HS was more intense than that for CS, and no increase in laminin or collagen type IV was observed. In the AA cases, amyloid deposits were distributed in the capillaries, small arterioles, interstitium of the myocardium and mucosa. Immunoreactivity for laminin and collagen type IV was marked, and more intense than that for HS and CS. Although the existence of a direct relationship between increase in extracellular matrix material and amyloidogenesis remains to be proven, the observed variation in extracellular matrix changes in the background of each type of amyloidosis may indicate different binding sites of the amyloid precursor proteins, resulting in the specific histological features and distribution. Received: 23 August 1996 / Accepted: 9 January 1997     

Tumor necrosis factor, interleukin-1 and beta 2-microglobulin levels in chronic hemodialysis patients

We measured tumor necrosis factor (TNF alpha), interleukin-1 (IL1-B), and beta-2 microglobulin (B2M) levels in 10 chronic hemodialysis patients before and during dialysis with six different dialysate/dialyzer combinations. The mean pre-dialysis serum level of B2M was 23.4 +/- 11.1 mg/L (nl less than 3 mg/L). There was no significant effect of hemodialysis with any dialysate/dialyzer combination on intradialytic serum B2M levels. Five patients had detectable pre-dialysis serum levels of TNF alpha (greater than 40 pg/ml) at least once and 2 had detectable levels prior to all dialyses. Six patients had detectable pre-dialysis serum levels of IL1-B (greater than 20 pg/ml) at least once, and 2 had detectable levels prior to all dialyses. Serum TNF alpha, IL1-B and B2M levels were not significantly correlated with one another. Our data do not support the hypothesis that blood-membrane interactions significantly affect circulating levels of TNF alpha, IL1-B or B2M. Chronic high level elevations of plasma IL1-B and TNF alpha are not uniformly observed in hemodialysis patients, arguing against a role for these substances as systemic uremic toxins.     

Innervation of spinal ligaments of patients with disc herniation. An immunohistochemical study.

The purpose of this work was to demonstrate whether neural elements are present in the spinal ligaments removed from patients with disc herniation. The tissue samples were stained by an immunohistochemical technique using antibodies to neurofilament protein (NFP) subunits as specific markers. Numerous NFP-immunoreactive nerve fibers and free nerve endings were demonstrated within the ligamentous structures. These findings were discussed relative to the low-back pain of disc herniated patients.     

Tumoral amyloidosis of bone of beta 2-microglobulin origin in association with long-term hemodialysis: a new type of amyloid disease

Amyloid lesions of bone are rare and limited almost exclusively to patients with amyloidosis secondary to plasma cell dyscrasias. The present report describes the cases of two patients receiving long-term hemodialysis (nine and 12 years) who had multiple lytic lesions of bone proved by biopsy to contain an unusual type of amyloid. Results of serum protein electrophoreses and immunoelectrophoreses, as well as bone marrow examinations, were normal. In both cases the amyloid displayed characteristic Congo red affinity and birefringence on polarized light microscopy that was inhibited by potassium permanganate treatment of sections prior to staining. Although this staining reaction was described previously exclusively in AA amyloid (i.e., the material associated with classic secondary amyloidosis), immunoperoxidase staining for AA protein in these cases was negative. Transmission electron microscopy revealed the amyloid fibrils to have unusual curvilinear configurations. Immunoperoxidase staining for beta 2-microglobulin (beta 2m) was positive in the amyloid lesions of both patients at the light microscopic level. Ultrastructural immunohistochemical studies for beta 2m, performed in one case, were positive. Both patients had markedly elevated serum beta 2m levels. By Ouchterlony immunodiffusion, purified beta 2m demonstrated partial identity with purified amyloid protein fractions and a serum constituent. Bone lesions composed of amyloid related to beta 2M probably represent a new subgroup of amyloid disease that may be linked to renal failure and long-term hemodialysis.     

Blastomycosis and opportunistic infections in patients with acquired immunodeficiency syndrome. An autopsy study.

Patients with acquired immunodeficiency syndrome (AIDS) are subject to a host of opportunistic infections, but to our knowledge a predisposition to blastomycosis has not previously been established. Autopsies of two patients with AIDS revealed disseminated blastomycosis with massive pulmonary involvement, Blastomyces meningoencephalitis, and widespread dissemination. The massive systemic involvement and rapid terminal course in both cases may reflect the state of acquired immunodeficiency. An analysis of an autopsy series showed that the incidence of blastomycosis was increased in patients with AIDS, although some other opportunistic organisms were more common (eg, Pneumocystis carinii, Mycobacterium avium-intracellulare, and Candida species). Thus, the diagnosis and treatment of blastomycosis must be pursued in patients with AIDS. Additional data are needed to further determine the incidence of blastomycosis in the population of patients with AIDS.     

Systemic amyloidosis of beta 2-microglobulin type: a complication of long-term haemodialysis.

A patient receiving long-term haemodialysis developed systemic amyloidosis, which was shown immunohistochemically to be of beta 2-microglobulin type, a previously unrecognised form of systemic amyloidosis. Histologically, the amyloid deposits were closely associated with foci of acute and granulomatous inflammation and vasculitis, although it was not clear if the amyloid deposits directly caused the inflammatory process, or if amyloid was deposited preferentially in areas of inflammation of uncertain aetiology.     

Cyclooxygenase-2 immunoreactivity in the ischemic neonatal human brain. An autopsy study

Cyclooxygenase-2 (COX-2) is known to be expressed in rat brain and up-regulated by ischemia. The administration of COX inhibitors before as well as soon after the ischemic insult reduces the extension of cerebral damage in rats. Overexpression of COX-2 has also been shown in the ischemic brain of adult human patients, while no information concerning COX-2 expression in neonatal ischemia is available. Intrapartum asphyxia and perinatal brain injury may result in cerebral palsy, mental retardation or epilepsy. COX-2 expression in the brain of neonates delivered after severe birth asphyxia was investigated using immunohistochemistry. Meningeal vessel walls of term and preterm babies widely expressed COX-2 immunoreactivity, as did periventricular large vessels in preterms. A number of brain cells (mature and immature cortical, periventricular and basal ganglia neurons, and oligodendrocytes of the cerebral white matter in brains from term neonates) also expressed COX-2. The present findings suggest that COX-2 may take part in enhancing neonatal brain damage via different mechanisms, such as those involving excitotoxicity and production of reactive oxygen species.