Beta 2-microglobulin Amyloid Deposition Research Articles

The unresolved problem of beta-2 microglobulin amyloid deposits in the intervertebral discs of long-term dialysis patients

BackgroundDialysis-related destructive spondyloarthropathy caused by beta-2 microglobulin (β2M) amyloid deposits in intervertebral discs is a major burden for patients undergoing long-term dialysis. This study aimed to quantify the presence of β2M amyloid deposits in the intervertebral disc tissue of such patients and analyze whether there was a significant correlation between β2M accumulation and the duration of dialysis.MethodsTwo groups of patients who had undergone surgery for degenerative spinal pathologies were selected: the dialysis group (n = 29) with long-term dialysis and the control group (n = 10) with no renal impairment. Tissue sections were prepared from specimens of intervertebral disc tissue obtained during spinal surgery and analyzed via histological staining, including immunohistochemistry (IHC) and Congo red.ResultsThere was a statistically significant multifold increase of β2M expression in the disc tissue of long-term dialysis patients when compared to non-dialysis patients, as shown by both IHC (0.019 ± 0.023 μm2 vs. 0.00020 ± 0.00033 μm2, respectively; p = 0.012) and Congo red staining (0.027 ± 0.041 μm2 vs. 9.240 × 10−5 ± 5.261 × 10−5 μm2, respectively; p = 0.047). We also note a moderate strength positive correlation between the duration of dialysis and positive IHC (r = 0.39; p = 0.015) and Congo-red staining (r = 0.42; p = 0.007).ConclusionsThe problem of β2M amyloidosis in long-term dialysis patients remains unresolved even with predominant use of high-flux dialysis membranes. This highlights the insufficiency of current dialysis modalities to effectively filter β2M.

Beta 2-microglobulin amyloid deposit in HLA-B27 transgenic rats

Beta 2-microglobulin (beta 2-m) amyloid deposition develops serious orthopedic complications in patients with long-term hemodialysis. However, the exact pathogenesis of amyloid deposition in patients with dialysis is unknown. We used transgenic rats with HLA-B27 and beta 2-m to develop an in vivo animal model with beta 2-m amyloid-associated disorders to investigate the mechanism of formation and to report histological findings of beta 2-m amyloid deposition. Transgenic rats were divided into two groups: group 1, no treatment; group 2, arthritis induced by type II collagen. A large number of cells labeled with beta 2-m were observed in the bone marrow and synovium of the knee joint in transgenic rats. In addition, amyloid deposition, identified by Congo red staining, was found only in the knee joints of the transgenic rats with collagen-induced arthritis. Immunostaining with beta 2-m demonstrated the same pattern of tissue distribution as Congo red in serial sections. We hypothesized that elevated serum beta 2-m level-associated local chronic inflammation leads to the development of amyloid deposits and resultant arthropathy.

Beta 2-microglobulin amyloid deposit in HLA-B27 transgenic rats

Beta 2-microglobulin (beta 2-m) amyloid deposition develops serious orthopedic complications in patients with long-term hemodialysis. However, the exact pathogenesis of amyloid deposition in patients with dialysis is unknown. We used transgenic rats with HLA-B27 and beta 2-m to develop an in vivo animal model with beta 2-m amyloid-associated disorders to investigate the mechanism of formation and to report histological findings of beta 2-m amyloid deposition. Transgenic rats were divided into two groups: group 1, no treatment; group 2, arthritis induced by type II collagen. A large number of cells labeled with beta 2-m were observed in the bone marrow and synovium of the knee joint in transgenic rats. In addition, amyloid deposition, identified by Congo red staining, was found only in the knee joints of the transgenic rats with collagen-induced arthritis. Immunostaining with beta 2-m demonstrated the same pattern of tissue distribution as Congo red in serial sections. We hypothesized that elevated serum beta 2-m level-associated local chronic inflammation leads to the development of amyloid deposits and resultant arthropathy.

Dialysis-related amyloidosis of the heart in long-term hemodialysis patients

Dialysis-related amyloidosis (DRA) predominantly occurs in the osteoarticular structures, but it also systemically appears in the extra-articular tissues as well. However, the pathological characteristics of DRA in the hearts of hemodialysis (HD) patients have rarely been reported. We studied the pathological characteristics of DRA in the hearts of 18 HD patients, including its relationship to calcification. Furthermore, we studied the immunohistochemical localization of advanced glycation end products (AGEs) using monoclonal anti-imidazolone and anti-Nepsilon-(carboxymethyl)lysine (CML) antibodies. beta2-microglobulin (beta2m) amyloid deposits were detected in the hearts of seven patients who had undergone HD for more than 10 years. beta2m amyloid deposits in the left atrium were localized in the endocardium, the myocardium, and the walls of small blood vessels, whereas in the left ventricle, they were localized only in the walls of small blood vessels. The extent and prevalence of DRA in the heart were severe in the patients on HD for more than 15 years. Most calcification areas near mitral valve were dotted with beta2m amyloid deposits, while diffuse fine calcification was localized within the beta2m amyloid tissues in some cases. Imidazolone and CML were localized not only in massive beta2m amyloid deposits, but also in cardiac myocytes. DRAs were localized extensively in the hearts of long-term HD patients. A strong affinity was observed between beta2m amyloid deposits and calcification.

Pathogenesis of beta2-microglobulin amyloidosis.

Hemodialysis-related amyloidosis is a relatively new form of systemic amyloidosis, with beta2-microglobulin (B2M) being identified as the major constituent protein. Most of the clinical findings are related to amyloid deposition in osseo-articular tissues. B2M amyloid deposits first appear in the cervical intervertebral discs, which are well known to be susceptible to mechanical stress. A close relationship between changes of microenvironment caused by such stress and amyloid deposition is highly suggested. In advanced cases, an inflammatory reaction composed of macrophages, multinucleated giant cells, and granulation tissue, is observed around the amyloid deposits. Purified amyloid protein is native B2M, and mutations and proteolysis are not believed to be important for its deposition. Plasma levels of B2M are elevated as much as 5-10 times because of the inability of hemodialysis equipment removal of B2M from blood plasma, the duration being very important for B2M amyloid fibrillogenesis. Heparan sulfate proteoglycans, perlecan, is increased at the same sites of amyloid deposits from the early stages. In B2M amyloidosis, an increase of heparan sulfate proteoglycans is observed in the vascular wall and synovium, but in the discs, ligaments and cartilage, there is an increase of chondroitin sulfate proteoglycans predominantly. B2M has an affinity for heparan sulfate proteoglycans, although it is weaker than that for laminin and type IV collagen. This is related to the interactions between negative charges of sulfate groups of proteoglycans and positive charges of basic amino acids in N-terminal side of B2M. Increased cytokines production in the synovium, induced by advanced glycation end products as well as elevated plasma levels, is also linked to inflammatory reactions. Increased expression of matrix metalloproteinases (MMP), especially MMP-1 and -9, is related to the destructive changes of the bone and cartilage. The decrease of plasma levels by high flux membrane and control of inflammatory reactions are very important for prevention of B2M amyloidosis.

'Carbonyl stress' and dialysis-related amyloidosis.

Advanced glycation end products (AGEs) are formed by nonenzymatic glycation and oxidation (glycoxidation) reactions. As AGE formation is related to hyperglycaemia, they have been implicated in the pathogenesis of diabetic complications. They also increase in normoglycaemic uraemic patients: AGEs, such as pentosidine and carboxymethyllysine (CML), are elevated in both the plasma proteins and skin collagen of uraemic patients, being several times greater than in normal subjects and nonuraemic diabetic patients. However, AGE concentrations do not differ between diabetics and non-diabetics in uraemia. AGE accumulation in uraemia, therefore, cannot be attributed to hyperglycaemia, or simply to the decreased removal by glomerular filtration of AGE-modified proteins as over 90% of plasma pentosidine and CML are linked to albumin. Recently, evidence has suggested that, in uraemia, the increased carbonyl compounds, derived from both carbohydrates and lipids, modify proteins both by the glycoxidation reaction (leading to augmented AGE production) and also by the lipoxidation reaction (leading to the augmentation of the advanced lipoxidation end product, ALE, production). Thus, uraemia might be a state of carbonyl overload with potentially damaging proteins ('carbonyl stress'). Carbonyl stress in uraemia appears to be relevant to long-term complications associated with chronic renal failure and dialysis, such as dialysis-related amyloidosis. Immunohistochemical studies, with specific antibodies to AGEs and ALEs, identified carbonyl stress in long-lived beta2-microglobulin amyloid deposits. Furthermore, proteins modified with carbonyl stress exhibit several biological activities through interactions with several types of cell, e.g. monocytes/macrophages, synovial cells and osteoclasts/osteoblasts, which might partially account for dialysis arthropathies.

Circulating biochemical markers of bone remodeling in uremic patients

Chronic renal failure is often associated with bone disorders, including secondary hyperparathyroidism, aluminum-related low-turnover bone disease, osteomalacia, adynamic osteopathy, osteoporosis, and skeletal beta2-microglobulin amyloid deposits. In spite of the enormous progress made during the last few years in the search of noninvasive methods to assess bone metabolism, the distinction between high- and low-turnover bone diseases in these patients still frequently requires invasive and/or costly procedures such as bone biopsy after double tetracycline labeling, scintigraphic-scan studies, computed tomography, and densitometry. This review is focused on the diagnostic value of several new serum markers of bone metabolism, including bone-specific alkaline phosphatase (bAP), procollagen type I carboxy-terminal extension peptide (PICP), procollagen type I cross-linked carboxy-terminal telopeptide (ICTP), pyridinoline (PYD), osteocalcin, and tartrate-resistant acid phosphatase (TRAP) in patients with chronic renal failure. Most of the observations made by several groups converge to the conclusion that serum bAP is the most sensitive and specific marker to evaluate the degree of bone remodeling in uremic patients. Nonetheless, PYD and osteocalcin, in spite of their retention and accumulation in the serum of renal insufficient patients, are also excellent markers of bone turnover. The future generalized use of these markers, individually or in combination with other methods, will undoubtedly improve the diagnosis and the treatment of the complex renal osteodystrophy.

Beta 2-microglobulin amyloid deposition in hip revision arthroplasty tissues.

Hip joint disease associated with progressive amyloid deposition in uraemic patients receiving chronic haemodialysis treatment often requires treatment by joint arthroplasty. The aim of this study was to determine whether beta 2-microglobulin amyloid deposition occurred in the periprosthetic tissues of arthroplasties that had undergone aseptic loosening and required a revision procedure. Sections of the pseudocapsule, acetabular and femoral pseudomembrane surrounding failed total hip replacements of five uraemic patients known to have beta 2-microglobulin amyloid deposits at the time of primary joint replacement were examined for the presence of beta 2-microglobulin amyloid deposition by Congo red staining and immunohistochemical staining for beta 2-microglobulin and other amyloid proteins. Clinical and radiological features of each case, including postoperative history and extent of osteolysis, were also noted. In all cases evidence of beta 2-microglobulin amyloid deposits were found in one or more of the above periprosthetic tissues. In three of these cases amyloid deposition was extensive. This study shows that beta 2-microglobulin amyloid deposition occurs in revision arthroplasty tissues. Accelerated loosening of the prosthesis is known to occur in uraemic patients and it is possible that beta 2-microglobulin amyloid deposition may contribute to early arthroplasty failure in uraemic patients who remain on haemodialysis treatment.

Implication of the glycoxidation and lipoxidation reactions in the pathogenesis of dialysis-related amyloidosis (Review).

Dialysis-related amyloidosis is recognized as a serious bone and joint complication in long-term dialysis patients. Beta2-microglobulin has been demonstrated to be a major constituent of the amyloid fibrils. However, the molecular pathogenesis of this disorder remains unknown. Recent biochemical and immunohistological studies have identified a new modification of beta2-microglobulin in the amyloid fibrils, i.e., the advanced glycation end products (AGEs). AGEs are formed by non-enzymatic glycative and oxidative (glycoxidation) reactions. The levels of AGEs, such as pentosidine and carboxymethyllysine (CML), are elevated in both the plasma proteins and skin collagen of non-diabetic dialysis patients several times more than in normal subjects. The AGE accumulation in uremia cannot be attributed to hyperglycemia, nor simply to their decreased renal clearance. Recently, gathered evidence has suggested that, in uremia, an increase in carbonyl compounds, derived from both carbohydrates and lipids, modifies proteins, leading to the augmentation of the production of not only AGEs, but also the advanced lipoxidation end products (ALEs). Uremia might thus be a state of carbonyl overload with potentially damaging proteins ('carbonyl stress'). Immunohistochemical studies, with antibodies specific to AGEs and ALEs, identified carbonyl stress in long-lived beta2-microglobulin amyloid deposits. Furthermore, proteins modified by carbonyl stress exhibit a variety of biological activities towards several types of cells, which might partially account for dialysis arthropathies.

Interaction between β2-microglobulin and advanced glycation end products in the development of dialysis related-amyloidosis

Dialysis related amyloidosis (DRA) is a progressive debilitating complication of long-term dialysis. beta 2-microglobulin (beta 2m) amyloid deposition occurs preferentially in older patients and initially is located in collagen-rich osteo-articular tissues. Since an age-dependent increase in the formation of advanced glycation end products (AGE) has been observed in collagen-containing structures, we hypothesized that AGE-modified beta 2m in the amyloid of DRA may be formed locally in osteo-articular structures as a subsequent event of its binding to collagen-AGE. Based on this hypothesis, we investigated the binding between beta 2m and AGE-modified collagen (collagen-AGE) in vitro. Significantly larger amounts of human beta 2m were bound to types I to IV of immobilized collagen-AGE than to unmodified collagens (P < 0.0001). The quantity of beta 2m bound to collagen-AGE was dependent on the concentrations of both beta 2m and of AGE contained in collagen (P < 0.01). Unmodified beta 2m was more avidly bound to collagen-AGE or collagen in comparison to AGE-modified beta 2m (P < 0.0001). beta 2m bound to collagen-AGE could be modified further by nonenzymatic glycosylation during three weeks of incubation with physiologic concentrations of glucose. Similar processes in vivo may be important in the pathobiology of DRA.

Miscellaneous metabolic diseases.

Musculoskeletal manifestations are commonly observed in metabolic disorders. Here we review the recent literature on several metabolic arthropathies. Hemochromatosis should be suspected in patients with the sign of the "iron salute". Screening for this disorder by routine measurement of transferrin saturation appears to be a cost-effective procedure in white men aged 30 years or older. In dialysis arthropathy, radiologic lesions of the hand joints increased in size and frequency with the duration of dialysis. However, destructive arthropathy of the fingers is not necessarily related to amyloid deposition. In patients with dialysis-related beta 2-microglobulin amyloid deposition, renal transplantation improved clinical rheumatologic manifestations but did not prevent progression of destructive arthropathies nor dissolution of amyloid deposits. In ochronotic arthropathy, spinal changes may resemble those seen in ankylosing spondylitis and can lead to cord compression. The presence of brownish-blackish rods in the synovial fluid is an unusual but useful diagnostic tool. Metabolic factors are likely to play a role in the pathogenesis of diffuse idiopathic skeletal hyperostosis, and recent studies have demonstrated elevated insulin and growth hormone but normal insulin-like growth factor-1 levels in these patients. Other metabolites that may play a role in this condition include retinoids and bone morphogenetic protein-2.

Glycosaminoglycans in intervertebral disc amyloid deposits.

Intervertebral discs are a common site of localized articular and some forms of systemic articular amyloid deposition. Whether there is an intrinsic matrix factor that favours amyloid deposition in intervertebral disc connective tissues is uncertain, but it is known that small localized deposits of amyloid in intervertebral discs are largely age related. As the glycosaminoglycans (GAGs) composition of the intervertebral disc is known to change with age, and as some forms of systemic amyloid deposition have been shown to be associated with particular highly sulphated GAGs, we examined the GAGs profile of amyloid deposits in intervertebral discs using mucin histochemistry (Alcian blue: MgCl2 critical electrolyte concentration) and immunohistochemistry. We found strong staining for very highly sulphated GAGs (0.9 M and 1 M MgCl2) and confirmed the presence of keratan sulphate in both localized and systemic, dialysis-associated beta 2-microglobulin amyloid deposits within disc fibrocartilage. These findings suggest that qualitative and quantitative changes in matrix GAGs, particularly strongly sulphated GAGs such as keratan sulphate, may play a role in the pathogenesis of localized and systemic amyloid deposition in intervertebral discs.

Dialysis arthropathy: Outcome after renal transplantation

Patients treated by long-term maintenance hemodialysis frequently develop a form of chronic arthropathy that is strongly associated with beta 2-microglobulin amyloid deposition and related, at least in part, to beta 2-microglobulin retention. Successful renal transplantation is followed by a rapid fall in serum beta 2-microglobulin levels and might allow dissolution of amyloid deposits. The purpose of this work was to investigate the effects of renal transplantation on dialysis arthropathy. Fourteen renal transplant recipients were selected on the basis of previous hemodialysis treatment for at least 10 years (mean 16) and a history of chronic joint pain prior to transplantation. They all received 10 to 17.5 mg/d of prednisone. Posttransplant rheumatologic manifestations were studied prospectively and compared to pretransplant rheumatologic manifestations recorded in medical charts and reported during patient interviews. Pretransplant and posttransplant articular roentgenograms were separately analyzed by three observers who were blinded to timing of the films. Beta 2-microglobulin amyloid was identified by Congo red staining and immunohistology. After a mean posttransplant interval of 54 months (range 12 to 121), the articular condition was improved in 10 patients, unchanged in 1, and worsened in 3, according to patients' assessments. The number of painful joints decreased significantly (P < 0.05) as compared to the pretransplant period. However, the number and size of subchondral bone erosions remained unchanged, destructive arthropathies generally worsened, and articular beta 2-microglobulin amyloid deposits were identified in 2 patients, 2 and 10 years after renal transplantation, respectively. Renal transplantation appeared to arrest progression of beta 2-microglobulin amyloid in dialysis patients, but it neither led to dissolution of deposits nor prevented progression of destructive arthropathies. Most articular symptoms were improved, probably as a result of corticosteroid therapy.

Dialysis Arthropathy of the Hip

Beta 2-microglobulin amyloid deposition is associated with a destructive arthropathy in the hip of chronic hemodialysis patients. Twenty-five hips from 18 patients were assessed for the presence and immunohistochemical type of amyloid. The hemodialysis group was compared with an age- and disease-matched control group that had no evidence of renal failure. Beta 2-microglobulin amyloid deposits were present in all patients who had been on hemodialysis for 18 months or more. Beta 2-microglobulin amyloid deposits were not found in patients who had been on hemodialysis for less than 18 months. Amyloid deposits were seen first in the articular cartilage and later involved the synovial membrane, joint capsule, and subchondral bone as well. The presence and amount of amyloid deposition correlated to the duration of hemodialysis. Severely affected hip roentgenographically had a concentric loss of joint space, periarticular erosions, and cystic lesions in the femoral head and acetabulum. These pathologic and roentgenographic changes suggest that amyloid deposition leads directly to the erosive hip arthropathy occurring in hemodialysis patients.

Destructive spondylo-arthropathy during long-term haemodialysis.

We reviewed 29 patients who had developed destructive arthropathy of the spine during long-term haemodialysis. Their mean age when haemodialysis began was 43.8 years; at diagnosis they had been dialysed for an average of 8.6 years. In 26 patients, the lesions were between C4 and C7; in six they were between L4 and S1, three having lesions in both regions. Sixteen patients had had previous surgery for carpal tunnel syndrome. Spinal surgery was performed in nine patients with satisfactory results in only five. We demonstrated beta-2 microglobulin amyloid deposits in the discs and surrounding ligaments in all biopsied cases. The natural history and management of this condition are not yet clear.

Cervical discs are most susceptible to beta2-microglobulin amyloid deposition in the vertebral column

Intervertebral discs of 41 chronic renal failure autopsy cases were examined histologically and immunohistochemically to assess the distribution of beta 2-microglobulin-associated (beta 2m) amyloid in the vertebral column. The results demonstrated beta 2m amyloid to appear first in the cervical discs, then in the lumbar and upper thoracic discs, and finally in the middle and lower thoracic discs as the dialysis period is prolonged. The shortest dialysis period for which beta 2m amyloid was detected was one year and seven months. Deposition of beta 2m amyloid was most remarkable in the C4-5, 5-6, and 6-7 levels, which are known to sustain severe mechanical stress in daily life. Thus it is suggested that local mechanical stress accelerates beta 2m amyloidosis. A marked macrophage reaction was observed around the amyloid in cases of severe amyloidosis, the macrophages themselves being immunohistochemically positive for IL-1 beta and TNF-alpha. Amyloid deposition and reactive inflammation mediated by cytokines appear to be closely related to the pathogenesis of destructive spondyloarthropathy.

Joint and Systemic Distribution of Dialysis Amyloid

Deposition of beta 2-microglobulin amyloid in the joints of dialysis patients is common and begins early in the course of treatment, but its pathogenic significance in the production of dialysis arthropathy is uncertain. The joints (hip, knee, shoulder, elbow, wrist, cervical and lumbar spine, sacroiliac joint) and systemic tissues of 19 autopsied patients who had undergone haemodialysis for between 6 and 231 months were examined histopathologically for the presence of beta 2-microglobulin amyloid; it was present in all joints examined, including those unassociated with radiological changes and those of patients who had been on haemodialysis alone for only 24 months. Osteoarticular beta 2-microglobulin amyloid deposits were also found in patients who had been treated mainly by continuous ambulatory peritoneal dialysis. Systemic amyloid deposition was only seen in patients who had been haemodialysed for more than 13 years and consisted of sparse tiny deposits in blood vessel walls.