Dialysis-related Amyloidosis: Is It Gone or Should It Be?

Hemodialysis-Related Amyloidosis in the Tongue

Dialysis-related amyloidosis (DRA) represents a group of relatively rare disorders characterized by the systemic extracellular deposition of insoluble fibrils of amyloid protein in long-term dialysis patients. We describe herein a case of relatively early DRA on the tongue of a long-term dialysis patient. A 67-year-old man with a 39-year history of dialysis was referred for diagnosis of a tongue mass. On examination, a collection of whitish-yellow papules was identified on the ventral surface of the tongue tip. The pathological diagnosis was DRA. Clinicians should be aware that long-term dialysis can cause oral amyloidosis of the tongue.

Hepatitis C virus and carpal tunnel syndrome in hemodialysis patients: a single center cross-sectional study

OBJECTIVES

Carpal tunnel syndrome (CTS) is a common complication in maintenance hemodialysis (MHD) patients and leads to disabilities and increased risk of mortality. Hepatitis C virus (HCV) infection is associated with inflammatory and oxidative stress, and HCV infection can be cured. This study aimed at evaluating the association of HCV infection with CTS.

METHODS

Using a cross-sectional design, anthropometric and laboratory data were collected. Serum β₂-microglobulin, HCV antibody and HCV-RNA were measured. CTS was diagnosed according to clinical manifestation, electrophysiological test or ultrasonography. The related factors for CTS were analyzed by multivariate logistic regression.

RESULTS

This study included 113 participants, of whom 33 (29.2%) patients were positive for HCV antibody and 18 (15.9%) were positive for HCV antibody and HCV-RNA. Thirty-two (28.3%) patients were diagnosed with CTS. There were significant differences in the dialysis vintage, age of onset of MHD, high-sensitivity C-reactive protein, serum β₂M, anti-HCV-positive, HCV-RNA-positive, HCV load values and urine volume category between the CTS group and non-CTS group (p < 0.05). High-sensitivity C-reactive protein (OR: 1.238, 95% CI: 1.071-1.431, p = 0.004), dialysis vintage (OR: 1.017, 95% CI: 1.008-1.026, p < 0.001) and HCV-RNA-positive (OR: 5.929, 95% CI: 1.295-27.132, p = 0.022) rather than anti-HCV-positive were related factors for CTS.

CONCLUSIONS

High-sensitivity C-reactive protein, dialysis vintage and HCV-RNA replication but not previous HCV-infection were related factors for CTS in MHD patients. Further studies are needed to clarify whether intervention is beneficial for preventing and delaying the progression of CTS in MHD patients with HCV-RNA replication.

Renal Rehabilitation: Exercise Intervention and Nutritional Support in Dialysis Patients

With the growing number of dialysis patients with frailty, the concept of renal rehabilitation, including exercise intervention and nutrition programs for patients with chronic kidney disease (CKD), has become popular recently. Renal rehabilitation is a comprehensive multidisciplinary program for CKD patients that is led by doctors, rehabilitation therapists, diet nutritionists, nursing specialists, social workers, pharmacists, and therapists. Many observational studies have observed better outcomes in CKD patients with more physical activity. Furthermore, recent systematic reviews have shown the beneficial effects of exercise intervention on exercise tolerance, physical ability, and quality of life in dialysis patients, though the beneficial effect on overall mortality remains unclear. Nutritional support is also fundamental to renal rehabilitation. There are various causes of skeletal muscle loss in CKD patients. To prevent muscle protein catabolism, in addition to exercise, a sufficient supply of energy, including carbohydrates, protein, iron, and vitamins, is needed. Because of decreased digestive function and energy loss due to dialysis treatment, dialysis patients are recommended to ingest 1.2-fold more protein than the regular population. Motivating patients to join in activities is also an important part of renal rehabilitation. It is essential for us to recognize the importance of renal rehabilitation to maximize patient satisfaction.

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.

Nanobody-Based high-performance immunosorbent for selective beta 2-microglobulin purification from blood

Removing β2-microglobulin (β2M) from blood circulation is considered to be the most effective method to delay the occurrence of dialysis-related amyloidosis (DRA). The ideal extracorporeal β2M removal system should be cost-effective, highly specific and having a high capacity. However, the traditional technologies based on size exclusion do not have an adequate specificity, and alternative immunosorbents have limited applications due to low capacity and their high cost. Nanobodies (Nbs), the smallest functional recombinant antibody fragments, offer several advantages to overcome these obstacles. In this study, an anti-β2M Nb with a C-terminal thiol-tag was successfully prepared from E. coli for site-directed and oriented immobilization and usage as capture ligand in a β2M-selective immunosorbent. The prepared immunosorbent showed a high binding capacity of up to 7 mg β2M per mL resin, which is 17 times higher than that of previous studies using single-chain variable antibody fragments (scFv). Furthermore, an exceptional high specificity has been demonstrated as other human serum proteins were not adsorbed during dynamic adsorption experiments. About 80% of the original binding capacity of the immunosorbent was restored after four consecutive easy regenerations, whereas 90% of the original capacity was retained after 1-month storage of the resin. Moreover, the mathematical model fitted very well the in vitro perfusion. The results with this pioneering immunosorbent confirm its possible clinical application and is expected to reach the required clinical effect of immunoadsorption therapy. STATEMENT OF SIGNIFICANCE: Dialysis-related amyloidosis (DRA), associated with the accumulation of β2-microglobulin (β2M), is a serious complication of end-stage kidney disease. Removing β2M from blood circulation by extracorporeal blood purification is considered to be the most effective method to delay the occurrence of DRA. However, the existing methods are incapable to eliminate sufficient quantities of β2M from circulation, either because of lack of specificity, high cost or for low capacity. In this manuscript, we provide a practical and economic immunosorbent based on anti-β2M nanobody for DRA. The prepared immunosorbent was reusable and storable, and demonstrated high specificity and realized a high binding capacity of up to 7 mg β2M per mL resin, which is 17 times higher than that of the previous studies.

Patient-reported outcomes for cervical disease in end-stage renal disease patients: Propensity matching analysis using volunteer data

As the number of patients with end-stage renal disease (ESRD) has been increasing, the number of cervical spine surgeries for the patients with ESRD has also been increasing. The purpose is to identify the differences in cervical disease-specific patient-reported outcomes (PROs) between a healthy population and patients with ESRD, adjusting for subjects' age and physical activity.

METHODS

The ESRD group included patients with ESRD who were treated with hemodialysis in our outpatient clinic and healthy volunteers were individuals who attended public health lectures. Volunteers with a history of cervical disease were excluded. All participants answered the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) and questionnaires that evaluate the disability in performing physical activities.

RESULTS

A total of 111 participants were enrolled and divided into the ESRD group (n = 40) and the control group (n = 71). After adjusting for age and sex using propensity score, cervical function (p = 0.008), lower-extremity function (p = 0.007), and QOL (p < 0.001) in patients in the adjusted ESRD group were significantly lower than those in the control group. In multivariate linear regression, the use of hemodialysis was a significant variable that was negatively related to lower-extremity function (p = 0.004) and QOL (p = 0.011) independent of age and disability in performing physical activity.

CONCLUSION

The ESRD was a significant negative factor of lower-extremity function and QOL, independent of age, sex, and disability in performing physical activity. These results can help understand the cervical status of patients with ESRD and adjust the goal for such patients after cervical surgery.

Lower serum beta-2 microglobulin levels are associated with worse survival in incident peritoneal dialysis patients

Background

There is a general consensus that elevated serum beta-2 microglobulin (B2M) levels measured at a single time-point are significantly associated with mortality in patients on maintenance dialysis. To date, the majority of prior studies that have examined B2M-associated mortality have been conducted in prevalent hemodialysis patients with little residual renal function (RRF). However, studies in incident peritoneal dialysis (PD) patients are lacking. Moreover, changes in serum B2M levels over time have not been considered in this population.

Methods

We examined the association of time-updated and baseline serum B2M levels with mortality in a 10-year cohort of 725 incident PD patients who were maintained on dialysis between January 2006 and December 2011 using Cox proportional hazards regression analyses. Patients were categorized into tertiles according to B2M levels.

Results

During a median follow-up of 38 (interquartile range 23-64) months, 258 (35.4%) deaths occurred, including 106 (14.6%) and 86 (11.9%) deaths from cardiovascular and infectious causes, respectively. The lowest B2M tertile was associated with a higher risk of all-cause and infectious mortality compared with the middle tertile: the hazard ratios (95% confidence interval) for all-cause deaths were 2.12 (1.38-3.26) and 2.20 (0.96-5.05) in time-varying analyses and 1.52 (1.07-2.17) and 2.41 (1.19-4.88) in baseline analyses. Subgroup analyses showed that this association was particularly observed in females, older patients, those with comorbidities such as diabetes, a lower body mass index, lower albumin levels or those with higher RRF (all P for interactions <0.05).

Conclusions

In incident PD patients, lower B2M levels were independently associated with overall and infectious mortality. These associations can be potentially modified by malnutrition, inflammation and RRF.

An Organ System-Based Approach to Differential Diagnosis of Amyloid Type in Surgical Pathology

CONTEXT.—

Amyloidosis is an uncommon but important entity. A protein-based classification of amyloidosis defines the underlying disease process, directing clinical management and providing prognostic information. However, in routine surgical pathology there often is no attempt to classify amyloid other than staining to determine light chain-associated amyloidosis. Systemic and localized amyloidosis vary with respect to frequency of organ involvement by different amyloid types, and most amyloid proteins have commercial antibodies available for identification.

OBJECTIVE.—

To provide a guide for the likelihood of amyloid type by organ system.

DATA SOURCES.—

Literature review based on PubMed searches containing the word amyloid, specifically addressing the prevalence and significance of amyloid proteins in each organ system other than the brain, and the authors' practice experience.

CONCLUSIONS.—

In patients with amyloidosis, determination of the responsible protein is critical for appropriate patient care. In large subspecialty practices and reference laboratories with experience in using and analyzing relevant immunohistochemistry, most amyloid proteins can be identified with an organ-specific algorithm. Referring to an organ-based algorithm may be helpful in providing clinicians with a more specific differential diagnosis regarding amyloid type to help guide clinical evaluation and treatment. When the protein cannot be characterized, mass spectrometry can be performed to definitively classify the amyloid type.

Positron Emission Tomography Can Support the Diagnosis of Dialysis-Related Amyloidosis

BACKGROUND

The improvements in dialysis have not eliminated long-term problems, including dialysis-related amyloidosis (DRA), caused by Beta-2 microglobulin deposition. Several types of scintigraphy have been tested to detect DRA, none entered the clinical practice. Aim of the study was to assess the potential of PET-FDG scan in the diagnosis of DRA.

METHODS

Forty-six dialysis patients with at least one PET scan (72 scans) were selected out 162 patients treated in 2016-2018. Subjective global assessment (SGA), malnutrition inflammation score (A), Charlson Comorbidity Index (CCI), were assessed at time of scan; 218 age-matched cases with normal kidney function were selected as controls. PET scans were read in duplicate. Carpal tunnel syndrome was considered a proxy for DRA. A composite "amyloid score" score considered each dialysis year = 1 point; carpal tunnel-DRA = 5 points per site. Logistic regression, ROC curves and a prediction model were built.

RESULTS

The prevalence of positive PET was 43.5% in dialysis, 5% in controls (p < 0.0001). PET was positive in 14/15 (93.3%) scans in patients with carpal tunnel. PET sensitivity for detecting DRA was 95% (specificity 64%). Carpal tunnel was related to dialysis vintage and MIS. A positive PET scan was significantly associated with dialysis vintage, MIS and amyloid score. A prediction model to explain PET positivity combined clinical score and MIS, allowing for an AUC of 0.906 (CI: 0.813-0.962; p < 0.001).

CONCLUSIONS

PET-FDG may identify DRA, and may be useful in detecting cases in which inflammation favours B2M deposition. This finding, needing large-scale confirmation, could open new perspectives in the study of DRA.

Two years of maintenance hemodialysis has a pronounced effect on arterial stiffness progression

BACKGROUND

The change of aortic stiffness, but not the particular baseline value, plays a crucial role in estimating the patient risk with end-stage renal disease. Therefore, we aimed to analyze the evolution of central and peripheral arterial stiffness in hemodialysis population without previous cardiovascular events during a 2-year follow-up.

METHODS

60 hemodialysis patients (mean age 57.61 ± 13.01 years) were prospectively interviewed, and they underwent blood tests, chest X-ray for aortic calcification evaluation and pulse wave velocity (PWV) measurements at the baseline, after 6 months and after 2 years of observation period.

RESULTS

We found significant progression of aortic PWV (12.73 vs. 14.24 m/s, p = 0.032) and regression of brachial PWV (11.53 vs. 8.85 m/s, p < 0.001). CRP increase influenced evolution of aortic PWV (β = 0.331, p = 0.031, R² = 0.599). Higher β2-microglobulin values was related to the progression of aortic PWV (β = 0.219, p = 0.022, R² = 0.568). Mean arterial blood pressure had influence only on the short-term arterial stiffness evolution.

CONCLUSIONS

Patients on maintenance hemodialysis experience pronounced changes of arterial stiffness during the 2-year follow-up period. The progression of aortic stiffness is related to inflammatory response and particularly is influenced by β2-microglobulin concentration and aortic calcification.

Removal of blood amyloid-β with hemodialysis reduced brain amyloid-β, confirmed by brain imaging: a case report

The accumulation of amyloid-β protein (Aβ) in the brain signifies a major pathological change of Alzheimer's disease (AD). Extracorporeal blood Aβ removal system (E-BARS) has been under development as a tool for enhancing the clearance of Aβ from the brain. Previously, we revealed that dialyzers remove blood Aβs effectively, evoking substantial Aβ influx into the blood during hemodialysis sessions as one form of blood Aβ removal by E-BARS, and that postmortem brains of hemodialysis patients exhibited lower Aβ accumulation. Here, we present a case report of a 77-year-old male patient with end-stage renal failure whose Aβ accumulation in the brain declined by initiating and continuing hemodialysis for 6 months. This report suggests that blood Aβ removal by E-BARS could be an effective therapeutic method for AD.

Doxycycline treatment in dialysis related amyloidosis: discrepancy between antalgic effect and inflammation, studied with FDG-positron emission tomography: a case report

Background

No effective treatment is currently available and dialysis related amyloidosis continues to be invalidating in long-term dialysis patients. A recent case series reported reduction of osteoarticular pain on doxycycline treatment, extending the indications of this drug, used in other uncommon forms of amyloidosis, to dialysis patients. Explanations of the antalgic effect were the anti-inflammatory properties and anti-coiling effects of tetracycline.

Case presentation

Our report regards a 54-year-old woman, who was never transplanted and has been on hemodialysis and hemodiafiltration for overall 37 years, due to renal hypoplasia. In spite of high efficiency hemodiafiltration, she complained of increasing, invalidating osteoarticular pain; history and imaging suggested beta-2 microglobulin amyloid. Positron emission tomography (PET scan) identified metabolically active lesions in the involved settings. Low-dose doxycycline (100 mg/day) was started, leading to a considerable decrease in pain (over 6 months, from 7 to 8 to 4–5 on a 0–10 scale). At 6 months, a PET scan showed unmodified or increased uptake in the involved settings.

Conclusions

In summary, the previously described antalgic effect of doxycycline in dialysis related amyloidosis is confirmed in our case, the first studied using PET scan. The pattern at PET can suggests that the antalgic effect is independent from inflammation and points to other factors, such as interaction with fibril geometry or with bone structure.

Rediscovering Beta-2 Microglobulin As a Biomarker across the Spectrum of Kidney Diseases

There is currently an unmet need for better biomarkers across the spectrum of renal diseases. In this paper, we revisit the role of beta-2 microglobulin (β₂M) as a biomarker in patients with chronic kidney disease and end-stage renal disease. Prior to reviewing the numerous clinical studies in the area, we describe the basic biology of β₂M, focusing in particular on its role in maintaining the serum albumin levels and reclaiming the albumin in tubular fluid through the actions of the neonatal Fc receptor. Disorders of abnormal β₂M function arise as a result of altered binding of β₂M to its protein cofactors and the clinical manifestations are exemplified by rare human genetic conditions and mice knockouts. We highlight the utility of β₂M as a predictor of renal function and clinical outcomes in recent large database studies against predictions made by recently developed whole body population kinetic models. Furthermore, we discuss recent animal data suggesting that contrary to textbook dogma urinary β₂M may be a marker for glomerular rather than tubular pathology. We review the existing literature about β₂M as a biomarker in patients receiving renal replacement therapy, with particular emphasis on large outcome trials. We note emerging proteomic data suggesting that β₂M is a promising marker of chronic allograft nephropathy. Finally, we present data about the role of β₂M as a biomarker in a number of non-renal diseases. The goal of this comprehensive review is to direct attention to the multifaceted role of β₂M as a biomarker, and its exciting biology in order to propose the next steps required to bring this recently rediscovered biomarker into the twenty-first century.