Visceral involvement of dialysis amyloidosis

Beta-2 microglobulin and all-cause mortality in the era of high-flux hemodialysis: results from the Dialysis Outcomes and Practice Patterns Study

BACKGROUND

Beta-2 microglobulin (β2M) accumulates in hemodialysis (HD) patients, but its consequences are controversial, particularly in the current era of high-flux dialyzers. High-flux HD treatment improves β2M removal, yet β2M and other middle molecules may still contribute to adverse events. We investigated patient factors associated with serum β2M, evaluated trends in β2M levels and in hospitalizations due to dialysis-related amyloidosis (DRA), and estimated the effect of β2M on mortality.

METHODS

We studied European and Japanese participants in the Dialysis Outcomes and Practice Patterns Study. Analysis of DRA-related hospitalizations spanned 1998-2018 (n = 23 976), and analysis of β2M and mortality in centers routinely measuring β2M spanned 2011-18 (n = 5332). We evaluated time trends with linear and Poisson regression and mortality with Cox regression.

RESULTS

Median β2M changed nonsignificantly from 2.71 to 2.65 mg/dL during 2011-18 (P = 0.87). Highest β2M tertile patients (>2.9 mg/dL) had longer dialysis vintage, higher C-reactive protein and lower urine volume than lowest tertile patients (≤2.3 mg/dL). DRA-related hospitalization rates [95% confidence interval (CI)] decreased from 1998 to 2018 from 3.10 (2.55-3.76) to 0.23 (0.13-0.42) per 100 patient-years. Compared with the lowest β2M tertile, adjusted mortality hazard ratios (95% CI) were 1.16 (0.94-1.43) and 1.38 (1.13-1.69) for the middle and highest tertiles. Mortality risk increased monotonically with β2M modeled continuously, with no indication of a threshold.

CONCLUSIONS

DRA-related hospitalizations decreased over 10-fold from 1998 to 2018. Serum β2M remains positively associated with mortality, even in the current high-flux HD era.

Beta-2 Microglobulin Amyloidosis: Past, Present, and Future

Almost half a century has elapsed since the first description of dialysis-related amyloidosis (DRA), a disorder caused by excessive accumulation of β-2 microglobulin (B2M). Within that period, substantial advances in RRT occurred. These improvements have led to a decrease in the incidence of DRA. In many countries, DRA is considered a "disappearing act" or complication. Although the prevalence of patients living with RRT increases, not all will have access to kidney transplantation. Consequently, the number of patients requiring interventions for treatment of DRA is postulated to increase. This postulate has been borne out in Japan, where the number of patients with ESKD requiring surgery for carpal tunnel continues to increase. Clinicians treating patients with ESKD have treatment options to improve B2M clearance; however, there is a need to identify ways to translate improved B2M clearance into improved quality of life for patients undergoing long-term dialysis.

Uremic Toxicity: Present State of the Art

The uremic syndrome is a complex mixture of organ dysfunctions, which is attributed to the retention of a myriad of compounds that under normal condition are excreted by the healthy kidneys (uremic toxins). In the area of identification and characterization of uremic toxins and in the knowledge of their pathophysiologic importance, major steps forward have been made during recent years. The present article is a review of several of these steps, especially in the area of information about the compounds that could play a role in the development of cardiovascular complications. It is written by those members of the Uremic Toxins Group, which has been created by the European Society for Artificial Organs (ESAO). Each of the 16 authors has written a state of the art in his/her major area of interest.

Perspectives in Pediatric Pathology, Chapter 22. Testicular Involvement in Systemic Diseases

Normal testicular physiology requires appropriate function of endocrine glands and other tissues. Testicular lesions have been described in disorders involving the hypothalamus-hypophysis, thyroid glands, adrenal glands, pancreas, liver, kidney, and gastrointestinal tract. Testicular abnormalities can also associate with chronic anemia, obesity, and neoplasia. Although many of the disorders that affect the above-mentioned glands and tissues are congenital, acquired lesions may result in hypogonadism in children and adolescents.

A case of pulmonary dialysis-related amyloidosis with reticular opacity of the lung in a patient undergoing long-term dialysis

Dialysis-related amyloidosis (DRA) is one of the most important complications in long-term dialysis patients. Pulmonary involvement in patients with DRA has been rarely described, and lung radiographic findings have not yet been reported. The most common chronic lung disease process in chronic dialysis patients is interstitial fibrosis. This is the first case report of DRA presenting in the lung in a manner resembling interstitial pneumonia. This case study suggests that interstitial pneumonia as a result of DRA should be considered when dyspnoea and reticular opacity of the lung are observed in patients undergoing long-term dialysis.

Gastrointestinal beta2microglobulin amyloidosis in hemodialysis patients: biochemical analysis of amyloid proteins in small formalin-fixed paraffin-embedded tissue specimens

We present here a first report on the biochemical analysis of intestinal amyloid deposits found in two cases of hemodialysis-related amyloidosis. A new microtechnique was applied for extraction and immunochemical/chemical characterization of amyloid proteins in small amounts of fixed tissue, thus allowing precise identification of beta2microglobulin amyloid (Abeta2M) in both cases studied. The molecular mass of the identified amyloid beta2M was close to that of intact beta2M (12 kDa), with no evidence of the products of proteolytic fragmentation of these molecules. The isoelectrofocusing of the purified Abeta2M demonstrated a shift to more acidic pI as compared to the normal beta2M analyzed under the same experimental conditions. The obtained data suggest that the intestinal amyloid deposits in dialysis-related amyloidosis contain disease-specific beta2M isoforms, which could play a role in the pathogenesis of amyloid disease. The new methodology used might be useful in obtaining precise diagnosis of amyloidosis that is necessary for appropriate therapy, and also provide new important information on the chemical structure of amyloid proteins.

Pleural involvement of dialysis-related amyloidosis

Two cases of pleural involvement of dialysis-related amyloidosis (DRA) with pleural effusion are presented. DRA is one of the most important complications in long-term dialysis patients and beta2-microglobulin is the principal protein component of DRA, but pleural deposition of beta2-microglobulin amyloid has not yet been reported. To the best of the authors' knowledge, this is the first case report of pleural involvement of DRA presenting with pleural effusion. This case study suggests that pleural involvement of DRA should be considered when exudative pleural effusion is observed in patients undergoing long-term dialysis.

Gastrointestinal and pancreatic function in peritoneal dialysis patients: their relationship with malnutrition and peritoneal membrane abnormalities

BACKGROUND

Malnutrition is frequent in peritoneal dialysis (PD) patients, but the contribution of gastrointestinal (GI) dysfunction has not been well established.

METHODS

We studied GI function in 49 stable PD patients to ascertain its relationship with malnutrition. After an overload fat diet, fecal fat, sugar, starch and nitrogen, intestinal protein permeability (alpha(1)-antitrypsin fecal clearance [C-alpha(1)-AT]), fecal chymotrypsin (CT), GI hormones and gastrin, pepsinogen I and II, cholecystokinin (CCK), gastrin releasing peptide (GRP), and neuropeptide Y (NPY) were measured. Vasoactive intestinal polypeptide (VIP), substance P (SP), and tumor necrosis factor (TNF-alpha) and biochemical nutritional markers were evaluated.

RESULTS

All patients showed high fecal sugar. Elevated fecal nitrogen was found in 21 patients, 6 with high C-alpha(1)-AT. High fecal starch levels appeared in 21, fat in 20, and low fecal CT in 39 patients. These determinations showed inverse relation with nutritional markers. Increased fecal C-alpha(1)-AT values were associated with lower serum albumin. Fecal CT values showed a negative linear correlation with serum albumin and were inversely associated with retinol-binding protein, normalized protein nitrogen appearance, and serum iron. High plasma levels of pancreatic stimulating hormones were found: gastrin, CCK, and VIP. These levels were higher in patients with a worse pancreatic exocrine function. Higher values of other GI hormones, gastrin, pepsinogen I and II, CCK, GRP, and TNF-alpha. Normal concentrations of NPY, VIP, and PS were observed.

CONCLUSION

GI abnormalities (malabsorption, maldigestion, pancreatic dysfunction, and protein losing enteropathy) are present in an important number of PD patients. These features are negatively associated to nutrition.

Subcutaneous nodules on the buttocks as a manifestation of dialysis-related amyloidosis: a clinicopathological entity?

While beta 2-microglobulin amyloidosis occurring in patients undergoing long-term dialysis is frequently associated with joint involvement, skin lesions have rarely been encountered. We report a 57-year-old man with extensive subcutaneous amyloid deposition forming large nodules on the buttocks; the patient had been on maintenance dialysis for 28 years. Although this condition is rare, a review of the literature indicates that the majority of such lesions occur around the buttock region.

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.

[Treatments for amyloidosis beyond symptomatic care]

INTRODUCTION

Amyloid syndromes are pathogenetically different, each of the various amyloid diseases requiring specific treatment. Unfortunately, those treatments are often preventive and symptomatic, some efficient therapies being limited to particular types of amyloidosis.

CURRENT KNOWLEDGE AND KEY POINTS

Colchicine is effective in the prevention of amyloidosis due to familial Mediterranean fever but is less or not effective in other situations. Cytotoxic agents are useful in the treatment of AL amyloidosis with or without hemopoietic stem cell transplantation. Liver transplantation is indicated for familial polyneuropathy and kidney transplantation for dialysis-related beta 2 microglobulin amyloidosis.

FUTURE PROSPECTS AND PROJECTS

In vivo binding of serum amyloid P (SAP) (component shared by all amyloid deposits) to amyloid fibril, is a new avenue in the therapeutic approach. Development of radiolabeled SAP scintigraphy allows assessment of the disease outcome and evaluation of treatment-related effects. The various treatments that were assessed until now with the objective of curing the disease are reviewed.

UPPER GASTROINTESTINAL MUCOSA IN CHRONIC RENAL FAILURE - AN ENDOSCOPIC AND HISTOLOGICAL EVALUATION

Over a three year period, 98 patients of moderate to severe chronic renal failure (S creatinine > 5 mg/dl) admitted in our centre were evaluated for upper GI lesions. All patients underwent upper GI endoscopy. In 68% upper GI mucosa was affected. Various lesions encountered were gastritis (25.5%), duodenitis (10.2%), gastroduodenitis (21.4%), telengiectasia (5.1%), and peptic ulcer in 6.1%. In 74 patients three biopsies, one each from antrum, fundus and duodenum were taken. 45.9% of these had chronic gastritis and 14.8% chronic duodenitis. Prevalence of H pylori on histology was 17.56%. 20 patients (9.6%) developed upper GI bleed during hospitalisation. In 17 (85%) patients, where endoscopy could be done, gastritis/duodenitis/oesophagitis were the common underlying lesions.

Development of gastrointestinal beta2-microglobulin amyloidosis correlates with time on dialysis

Dialysis-associated beta2-microglobulin (beta2m) amyloidosis affects predominantly musculoskeletal tissue, but visceral involvement also occurs. To evaluate the clinical significance and prevalence of gastrointestinal beta2m amyloidosis, we studied hemodialysis patients admitted for gastrointestinal-related complaints. Hemodialysis patients (excluding those with non-beta2m amyloidosis) who were admitted with gastrointestinal complaints from 1984 to 1994 were identified. Gastrointestinal tissues from patients with available autopsy or surgical specimens were examined using hematoxylin and eosin stain, Congo red stain, and beta2m immunostain. Each case was evaluated independently by two pathologists and scored for quantity and location of beta2m amyloid and associated pathology. Of 24 patients, eight (four men and 4 women) had beta2m amyloid deposits within the gastrointestinal tract. Acute clinical presentation ranged from abdominal pain to gastrointestinal bleeding and was not significantly different for patients with or without gastrointestinal beta2m amyloid deposits. However, the mean time on dialysis of 15.3 +/- 5.7 years (range 6-24 years) for patients with gastrointestinal beta2m amyloidosis was significantly greater than that of patients without gastrointestinal beta2m amyloidosis (10.5 +/- 7.0 years, range <1 to 22 years, p < 0.05). Vascular histopathology ranged from mild focal thickening of vessel walls to massive vascular beta2m amyloid deposition with thrombosis. Extravascular beta2m amyloid ranged from mild to severe with marked expansion of the submucosa. Mucosal pathology ranged from none to severe ulceration. The degree of beta2m amyloid and the associated pathology tended to increase in severity with time on dialysis. Gastrointestinal beta2m amyloid deposition is an underappreciated complication of chronic hemodialysis that is significantly associated with increased time on dialysis. Gastrointestinal beta2m amyloidosis should be considered in any patient on hemodialysis 10 years or more who has gastrointestinal symptoms and can be identified in resection specimens as well as some biopsy specimens. Congo red stain and beta2m immunostains may be necessary for sensitive histopathologic evaluation of gastrointestinal beta2m amyloidosis.

Beta 2 microglobulin haemodialysis related amyloidosis: distinctive gross features of gastrointestinal involvement

Two cases of beta 2 microglobulin amyloidosis following long term haemodialysis found during necropsy are reported. The patients were 59 and 65 year old Japanese men, respectively. In both cases, systemic distribution of beta 2 microglobulin amyloid deposits was observed. The gastrointestinal tract including the stomach, small intestine, and colon showed the distinctive gross feature of rippled appearance, which was characterised by serosal wrinkles along the muscle layer arrangement. These areas were confirmed to contain deposits of beta 2 microglobulin in the muscularis propria. Although the outline of the muscle layers was preserved, most muscle fibres, encircled by the amyloid deposits, were atrophic or had disappeared microscopically. In neither case could a definite diagnosis of amyloidosis be made while the patient was alive. Interestingly, the oesophagus presented less involvement compared to the remainder of the gastrointestinal tract. In comparison with the AA or AL type of amyloidosis, beta 2 microglobulin haemodialysis related amyloidosis showed a rippled appearance of the serosal rather than mucosal changes, which may explain the difficulty in diagnosing amyloid deposits using biopsies of the gastrointestinal tract.

Interaction between beta 2-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.

Renal osteodystrophy

Renal osteodystrophy is a general complication of chronic renal failure and end-stage renal disease. The nature of renal osteodystrophy has changed since osteomalacia due to aluminum intoxication has become less prevalent. Osteomalacia has been replaced by the adynamic bone disorder. Suppression of osteitis fibrosa, calcitrol and control of secondary hyperparathyroidism has been shown to produce the adynamic bone disorder. Thus, many other factors besides secondary hyperparathyroidism and calcitrol deficiency contribute to the pathogenesis of renal osteodystrophy. Some of these factors, according to our current state of knowledge, are discussed in this chapter along with the presentation and treatment of renal osteodystrophy.

Mixed systemic amyloidosis in a patient receiving long term haemodialysis

A 64 year old woman had been receiving haemodialysis for 11 years. She had a history of chronic renal failure, caused by probable chronic pyelonephritis, and dialysis arthropathy. She died of acute pulmonary oedema and haemorrhage. At necropsy, histological, immunohistochemical, and ultrastructural studies showed widespread visceral deposits of beta 2-microglobulin (beta 2-M) and AA amyloid.

Pseudotumoral amyloidosis of beta 2-microglobulin origin in the buttock of a patient receiving long term haemodialysis

A 52 year old man who had been receiving haemodialysis for 13 years, with a history of renal tuberculosis, right ischial tuberculous osteomyelitis, and dialysis arthropathy, developed a soft tissue tumour in his left buttock. Histological analysis, immunohistological staining, and electron microscopic examination of the surgically removed tumour showed massive deposits of beta 2-microglobulin (beta 2-M) amyloid. This case shows the expanding clinical spectrum of this type of amyloidosis, and it is suggested that amyloid infiltration should be considered in the differential diagnosis of gluteal tumours in these patients.

The gastrointestinal tract in uremia

Gastrointestinal mucosal abnormalities ranging from edema to ulceration occur in two thirds of patients dying of uremia. Early studies suggested that uremic patients on maintenance dialysis treatment were at increased risk of peptic ulceration but more recent data indicate that this is not so. Other gastrointestinal problems reported for uremic subjects on maintenance dialysis treatment include bleeding from telangiectatic lesions, constipation, mucosal deposition of amyloid and acute pancreatitis. Nausea and vomiting are common in the uremic patient but gastric emptying studies have yielded conflicting results. Patients undergoing renal transplantation are at increased risk of development of esophagitis, complicated peptic ulcer, intestinal ulceration, and perforation as well as acute pancreatitis.

Spontaneous haemarthrosis in amyloid arthropathy of the shoulder

A patient is reported who has had episodes of spontaneous haemarthroses of the shoulder. On aspiration of the acute haemarthrosis, amyloid was found after appropriate staining of the centrifuged sediment. This may be a predisposing factor for haemarthrosis in haemodialysed patients.

beta 2-Microglobulin amyloidosis. A systemic amyloid disease affecting primarily synovium and bone in long-term dialysis patients

A number of rheumatic disorders occur in patients on long-term hemodialysis treatment. In recent years a clinical syndrome comprising carpal tunnel syndrome, destructive arthropathy, and cystic bone lesions has been recognized in these patients. Congo-red staining and microscopy in polarized light reveal a high frequency of amyloid in the affected tissues. Amino acid sequence data of the isolated major amyloid fibril protein show its identity with beta 2-microglobulin. beta 2-microglobulin amyloid has a predilection for synovial tissues and bone, but visceral deposits may also occur indicating the systemic nature of the disease. The clinicopathological features, pathogenesis, and diagnosis of beta 2-microglobulin amyloidosis are reviewed, and the therapeutic and prophylactic measures discussed. The identification of beta 2-microglobulin as an amyloidogenic protein has in an important way contributed to the understanding of the mechanisms of amyloidogenesis in general and emphasized the complexity of amyloid disease and the diversity of proteins capable of forming congophilic fibrillar deposits in human tissues.