Renal amyloidosis revisited: amyloid distribution, dynamics and biochemical type

Current status and prospect of anti-amyloid fibril therapy in AL amyloidosis

Amyloid light-chain (AL) amyloidosis is a rare hematological disease that produces abnormal monoclonal immunoglobulin light chains to form amyloid fibrils that are deposited in tissues, resulting in organ damage and dysfunction. Advanced AL amyloidosis has a very poor prognosis with a high risk of early mortality. The combination of anti-plasma cell therapy and amyloid fibrils clearance is the optimal treatment strategy, which takes into account both symptoms and root causes. However, research on anti-amyloid fibrils lags far behind research on anti-plasma cells, and there is currently no approved treatment that could clear amyloid fibrils. Nevertheless, anti-amyloid fibril therapies are being actively investigated recently and have shown potential in clinical trials. In this review, we aim to outline the preclinical work and clinical efficacy of fibril-directed therapies for AL amyloidosis.

Tubular basement membrane amyloid deposition: is it an indicator of renal progression in light chain amyloidosis?

In light chain amyloidosis (LA), the massive glomerular and vascular amyloid deposition leading to interstitial fibrosis/tubular atrophy (IFTA) is thought to be responsible for renal failure. The amyloid deposition in the interstitium and the tubular basement membrane (TBM) has received less attention in the study of LA. We, therefore, collected clinical and laboratory data on patients diagnosed with LA in our Nephrology Department and studied amyloid deposition in the TBM. Twelve LA patients were diagnosed by renal biopsy during a seven-year period. In 4 of the 12, amyloid deposition could also be detected in the TBM. In our first case of a patient with diabetes mellitus, non-amyloid fibrils resembling 'diabetic fibrillosis' were also seen by electron microscopy. Despite the double damage, IFTA was negligible, blood vessels were unaffected, and the glomerular deposition was segmental. In the other three cases, significant (>50%) IFTA and a severely reduced estimated glomerular filtration rate were already detected at the time of diagnosis and amyloid deposition was also observed in the blood vessels. These findings indicate the importance of TBM amyloid deposition in the progression of renal disease. This may represent a late-stage presentation of the disease with a heavy LC burden.

Amyloidosis and the Kidney: An Update

Various types of systemic amyloidosis can wreak havoc on the architecture and functioning of the kidneys. Amyloidosis should be suspected in patients with worsening kidney function, proteinuria, and multisystem involvement, but isolated kidney involvement also is possible. Confirming the amyloidosis type and specific organ dysfunction is of paramount importance to select the appropriately tailored treatment and aim for better survival while avoiding treatment-associated toxicities. Amyloid renal staging in light chain amyloidosis amyloidosis helps inform prognosis and risk for end-stage kidney disease. Biomarker-based staging systems and response assessment guide the therapeutic strategy and allow the timely identification of refractory or relapsing disease so that patients can be switched to salvage therapy. Kidney transplantation is a viable option for selected patients with amyloidosis. Because of the complex nature of the pathophysiology and treatment of amyloidosis, a multidisciplinary team-based approach should be used in the care of these patients.

Amyloidosis: What does pathology offer? The evolving field of tissue biopsy

Since the mid-nineteenth century pathology has followed the convoluted story of amyloidosis, recognized its morphology in tissues and made identification possible using specific staining. Since then, pathology studies have made a significant contribution and advanced knowledge of the disease, so providing valuable information on the pathophysiology of amyloid aggregation and opening the way to clinical studies and non-invasive diagnostic techniques. As amyloidosis is a heterogeneous disease with various organ and tissue deposition patterns, histology evaluation, far from offering a simple yes/no indication of amyloid presence, can provide a wide spectrum of qualitative and quantitative information related to and changing with the etiology of the disease, the comorbidities and the clinical characteristics of patients. With the exception of cardiac transthyretin related amyloidosis cases, which today can be diagnosed using non-biopsy algorithms when stringent clinical criteria are met, tissue biopsy is still an essential tool for a definitive diagnosis in doubtful cases and also to define etiology by typing amyloid fibrils. This review describes the histologic approach to amyloidosis today and the current role of tissue screening biopsy or targeted organ biopsy protocols in the light of present diagnostic algorithms and various clinical situations, with particular focus on endomyocardial and renal biopsies. Special attention is given to techniques for typing amyloid fibril proteins, necessary for the new therapies available today for cardiac transthyretin related amyloidosis and to avoid patients receiving inappropriate chemotherapy in presence of plasma cell dyscrasia unrelated to amyloidosis. As the disease is still burdened with high mortality, the role of tissue biopsy in early diagnosis to assure prompt treatment is also mentioned.

Prognostic value of histopathological scoring and grading in patients with renal AA amyloidosis

OBJECTIVE

The amount and distribution pattern of amyloid deposits may contribute to renal function and outcome, given the great diversity of renal involvement in amyloidosis. The aim of this study was to analyze the impact of histological characteristics of patients with biopsy-proven renal AA amyloidosis (AAA) on renal outcome.

METHODS

Renal biopsies of 37 patients with AAA were re-evaluated. The distribution pattern of glomerular amyloid (GA) deposits was classified, the extent of amyloid deposits in glomeruli, vessel, and interstitium and other histopathologic lesions were scored, and renal amyloid prognostic score (RAPS) was determined by summing all scores. Their potential prognostic relevance on renal outcome was investigated.

RESULTS

GA and vascular amyloid (VA) deposits were noted in all cases, interstitial amyloid (IA) was detected in 70.2%. GA deposits were predominantly seen in diffuse mesengiocapillary fashions (class IV) (51.4%). GA class, the extent of GA, VA, IA deposit, and RAPS, as well as interstitial fibrosis (IF) and interstitial inflammation were correlated to renal function at diagnosis. During the median follow-up of 52 months, 13 patients developed doubling of serum creatinine or end stage renal disease and they had a higher degree of GA and VA load (p = 0.03 and p = 0.042, respectively) as compared to the remaining patients. VA load, but not GA and RAPS grade, was associated with poor renal outcome (HR 3.016, 95% CI 1.45-6.25, p = 0.003).

CONCLUSIONS

Baseline renal function is closely linked to the extent of AA amyloid deposit in renal parenchyma but only VA load was a predictor of renal outcome in AAA patients.

Successful Treatment of AA Amyloidosis in Ankylosing Spondylitis Using Tocilizumab: Report of Two Cases and Review of the Literature

Historically, secondary amyloidosis has been a feared complication of chronic inflammatory conditions. The fibril protein AA derives from the acute phase reactant serum amyloid A (SAA). Long-term elevation of SAA levels remains a major risk factor for the development of AA amyloidosis in rheumatic diseases, and the prognosis may be unpredictable. Nowadays, with increased availability of effective biological agents, the incidence of AA amyloidosis seems to be declining. Still, genetically predisposed subjects with slowly progressive disease and mild symptoms combined with ongoing systemic inflammation may be at risk. Interleukin-6 (IL-6) is one of the drivers of SAA release and effectiveness of the humanized anti-IL-6 receptor antibody tocilizumab (TCZ) for the treatment of AA amyloidosis has been observed in some rheumatic conditions. Herein, we report two male subjects with longstanding ankylosing spondylitis (AS) complicated by renal amyloidosis who received TCZ with rapid and beneficial effects regarding inflammation and proteinuria. To the best of our knowledge, the use of TCZ in AS patients with this extra-articular manifestation has not previously been described. The paper includes histopathology, clinical follow-up, and longitudinal data of the two cases along with a comprehensive review of relevant literature. Mechanisms behind amyloid-mediated tissue damage and organ dysfunction are discussed. Altogether, our data highlight that blocking IL-6 signaling may represent a promising therapeutic option in patients with renal AA amyloidosis.

Differential expression of MAP3K7 and TROPONIN C proteins and related perturbations in renal amyloidosis

OBJECTIVES

Renal amyloidosis (RA) is a rare protein misfolding disorder that prompts progressive renal insufficiency. This study aimed to decipher proteomic changes in human sera to understand the pathophysiology and molecular mechanisms underlying the disease development, hence assisting in the diagnosis of RA.

METHODS

Serum proteomic analysis was performed using a gel-based approach followed by MALDI-TOF MS. RA patients with age and sex matched healthy volunteers were recruited from Max Super Speciality Hospital, New Delhi, India.

RESULTS

Proteome profiles of serum revealed eight differentially expressed proteins namely, Zinc finger protein 624, Protein FAM183A, Calcium-binding mitochondrial carrier protein Scamc-3, V-type proton ATPase 116 kDa subunit A isoforms 2, Protein TXNRD3NB, ATP - dependent RNA helicase, Troponin C and Mitogen-activated protein kinase kinase kinase 7. These proteins were reported first time in RA. The increased levels of MAP3K7 and TROPONIN C were validated by bio-layer interferometry and their diagnostic accuracy was evaluated by ROC curve analysis. The differentially expressed proteins were predominantly associated with vesicular trafficking, transcriptional regulation, metabolic processes, apoptotic process and mitochondrial metabolism.

CONCLUSION

The results indicate that these proteomic signatures may be considered as potential molecular targets for RA diagnostics and therapeutics subject to validation on large sample size. Abbreviations: AβP= Amyloid-beta protein, Aβ=Amyloid-beta, AL= Light chain amyloidosis, AA= Amyloid A, ALECT2= LECT2 amyloidosis, APS= Ammonium persulfate CKD= Chronic Kidney Diseases, EBRT= external beam radiation therapy, ESRD= End-Stage Kidney Disease, Glis2= Gli-similar 2, JNK= c-Jun NH 2-terminal kinase, MAPK= Mitogen-Activated Protein Kinase, MM=Multiple Myeloma, PHD= Prolyl hydroxylase, RA = Renal Amyloidosis, SAA= Serum Amyloid A, SD= Standard Deviation, Sepp= Selenoprotein, SCC= Squamous cell carcinoma, SDS= Sodium dodecyl sulfate, TEMED = tetramethyl ethylenediamine, TGF-Beta-1=Transforming growth factor- Beta-1, Trx = Thioredoxin, TrxR= Thioredoxin reductase.

A histopathological scoring and grading system to predict outcome for patients with AA amyloidosis

PURPOSE

Renal involvement is associated with significant morbidity and mortality in AA amyloidosis. Extend of amyloid deposition in kidney biopsies may be predictive for clinical manifestations and outcomes. The aim of our study is to assess clinical features of patients with biopsy-proven renal AA amyloidosis and to evaluate the relationship between histopathological scoring and grading of renal amyloid deposition with clinical findings and outcomes.

METHODS

The study included 86 patients who were diagnosed with renal AA amyloidosis. The demographic and clinical features at the time of biopsy and follow-up data were retrospectively collected. Amyloid deposition in glomeruli, interstitium, vessels and tubulointerstitial findings were scored and renal amyloid prognostic score (RAPS) was assigned by adding all scores. RAPS was further divided into three grades (RAPS grade I, II, III).

RESULTS

Median age was 50 (36-59) years. Familial Mediterranean fever was the leading cause. RAPS grade and interstitial inflammatory infiltration were associated with baseline eGFR and glomerular amyloid deposition was associated with proteinuria. During the follow-up period (median 50 months), 39 patients developed ESRD. Extensive (involving > 50%) glomerular amyloid deposition, baseline eGFR and proteinuria were independent risk factors for progression to end stage renal disease. Death censored renal survival was significantly lower among patients with RAPS grade III compared to those with RAPS grade I and II. Patient survival rate was not different according to RAPS grade.

CONCLUSIONS

Degree of renal amyloid accumulation is associated with renal function and outcome. The scoring and grading system may be predictive in clinical outcome and contribute to understanding of disease mechanism.

Correlation between amyloid deposits affecting renal compartments and glomerular filtration rate during renal biopsy in a renal amyloidosis case series

Amyloidosis comprises a group of disorders that accumulate modified autologous proteins in organs, mainly the kidneys. Few studies have addressed the amyloid compartmental distribution and associated clinical outcomes. The aim of this study was to present a case series of renal amyloidosis correlating histopathological data with glomerular filtration rate (GFR) during kidney biopsy. We studied 53 cases reviewed by nephropathologists from 2000 to 2018 in a single kidney biopsy center in Brazil. GFR was estimated using the CKD-EPI formula. Cases were divided into Group A ≥60 and Group B <60 mL·min⁻¹·(1.73 m²)⁻¹ using the estimated GFR during kidney biopsy. Semiquantitative histopathological study was performed, including extension and distribution of amyloid deposits by compartments (glomeruli, tubulointerstitial tissue, and vessels). Statistical analyses were made to understand associations with lower GFR. No difference was seen for age, gender, proteinuria, hematuria, subtype of amyloid protein, arteriosclerosis, interstitial fibrosis/infiltrate, or glomerular and interstitial amyloid deposits. After a previous P value <0.1 in the descriptive analysis, the following variables were selected: globally sclerotic glomeruli, high blood pressure, and the extension of vascular amyloid deposition. A binary logistic regression model with GFR as the dependent variable showed history of hypertension and vascular amyloid to be robust and independent predictors of Group B <60 mL·min⁻¹·(1.73 m²)⁻¹. Beyond the histopathologic diagnosis of amyloidosis, a semiquantitative approach on renal biopsy could provide new insights. Vascular amyloid is an independent predictor of renal dysfunction in cases of renal amyloidosis.

Renal amyloidosis: validation of a proposed histological scoring system in an independent cohort

Background

In systemic amyloidosis, the kidney is frequently affected and renal involvement has a major impact on survival. Renal involvement is clinically characterized by decreased estimated glomerular filtration rate (eGFR) and proteinuria. The two most common renal amyloidosis types are light chain-related amyloidosis (AL) and serum amyloid A (AA) amyloidosis. Standardized histopathological scoring of amyloid deposits is crucial to assess disease progression. Therefore, we aimed to validate the proposed scoring system from Rubinstein et al. (Novel pathologic scoring tools predict end-stage kidney disease in light chain (AL) amyloidosis. Amyloid 2017; 24: 205–211) in an independent patient cohort.

Methods

We attempt to reproduce the scoring system, consisting of an amyloid score (AS) and a composite scarring injury score (CSIS), in a multicentre AL and AA case series. Additionally, we analysed all renal amyloidosis kidney biopsies performed in the Netherlands between 1993 and 2012.

Results

Similar to the original study, AS and CSIS correlated to eGFR (r = −0.45, P = 0.0061 and r = −0.60, P < 0.0001, respectively) but not to proteinuria at diagnosis. Furthermore, AS, but not CSIS, was associated with renal outcome. The scoring system was not reproducible in AA patients. The median incidence rate for renal amyloidosis in the Netherlands was 2.3 per million population per year, and increased during the study period.

Conclusions

In our AL case series and the original study, AS and CSIS were correlated to eGFR but not to proteinuria, and AS correlated with renal outcome. Overall, we regard this scoring system as competent for standardized histopathological assessment of amyloid deposits burden and thereby disease advancement in renal biopsies.

Revisiting renal amyloidosis with clinicopathological characteristics, grading, and scoring: A single-institutional experience

INTRODUCTION:

Kidney involvement is a major cause of mortality in systemic amyloidosis. Glomerulus is the most common site of deposition in renal amyloidosis, and nephrotic syndrome is the most common presentation. Distinction between AA and AL is done using immunofluorescence (IF) and immunohistochemistry (IHC). Renal biopsy helps in diagnosis and also predicting the clinical course by applying scoring and grading to the biopsy findings.

MATERIALS AND METHODS:

The study includes all cases of biopsy-proven renal amyloidosis from January 2008 to May 2017. Light microscopic analysis; Congo red with polarization; IF; IHC for Amyloid A, kappa, and lambda; and bone marrow evaluation were done. Classification of glomerular amyloid deposition and scoring and grading are done as per the guidelines of Sen S et al.

RESULTS:

There are 40 cases of biopsy-proven renal amyloidosis with 12 primary and 23 secondary cases. Mean age at presentation was 42.5 years. Edema was the most common presenting feature. Secondary amyloidosis cases were predominant. Tuberculosis was the most common secondary cause. Multiple myeloma was detected in four primary cases. Grading of renal biopsy features showed a good correlation with the class of glomerular involvement.

CONCLUSION:

Clinical history, IF, and IHC are essential in amyloid typing. Grading helps provide a subtle guide regarding the severity of disease in the background of a wide range of morphological features and biochemical values. Typing of amyloid is also essential for choosing the appropriate treatment.

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.

Secondary, AA, Amyloidosis

Secondary, AA, amyloidosis is a rare systemic complication that can develop in any long-term inflammatory disorder, and is characterized by the extracellular deposition of fibrils derived from serum amyloid A (SAA) protein. SAA is an acute-phase reactant synthetized largely by hepatocytes under the transcriptional regulation of proinflammatory cytokines. The kidney is the major involved organ with proteinuria as first clinical manifestation; renal biopsy is the commonest diagnostic investigation. Targeted anti-inflammatory treatment promotes normalization of circulating SAA levels preventing amyloid deposition and renal damage. Novel therapies aimed at promoting clearance of existing amyloid deposits soon may be an effective treatment approach.

Kidney biopsy in AA amyloidosis: impact of histopathology on prognosis

In AA amyloidosis, while kidney biopsy is widely considered for diagnosis by clinicians, there is no evidence that the detailed investigation of renal histopathology can be utilized for the prognosis and clinical outcomes. In this study, we aimed to obtain whether histopathologic findings in kidney biopsy of AA amyloidosis might have prognostic and clinical value. This is a retrospective cohort study that included 38 patients who were diagnosed with AA amyloidosis by kidney biopsy between 2005 and 2013.The kidney biopsy specimens of patients were evaluated and graded for several characteristics of histopathological lesions and their relationship with renal outcomes. Segmental amyloid deposition in the kidney biopsy was seen in 29%, global amyloid deposition in 71, diffuse involvement of glomeruli in 84.2%, focal involvement in 7%, glomerular enlargement in 53%, tubular atrophy in 75% and interstitial fibrosis in 78% of patients. Histopathologically, glomerular enlargement, interstitial fibrosis, tubular atrophy, interstitial inflammation and global amyloid deposition were significantly associated with lower estimated glomerular filtration rate (eGFR) (p = .02, p < .001, p = .001, p = .009, p = .002, respectively) in univariate analysis. In multivariate analysis, tubular atrophy was the only predictor of eGFR (p = .019 B = -20.573). In the follow-up at an average of 27 months, 18 patients developed end-stage renal disease (ESRD). Among them, global amyloid deposition was the only risk factor for the development of ESRD (p = .01, OR = 18.750, %95 CI= 2.021-173.942). This is the first study showing that the histopathological findings in kidney biopsy of AA amyloidosis might have a prognostic and clinical value for renal outcomes.

Contribution of human smooth muscle cells to amyloid angiopathy in AL (light-chain) amyloidosis

OBJECTIVE

Amyloid light-chain (AL) amyloidosis is a disease process that often compromises the peripheral vascular system and leads to systemic end-organ dysfunction. Although amyloid formation in vessel walls is a multifaceted process, the assembly of the native light chains (LCs) into amyloid fibrils is central to its pathogenesis. Recent evidence suggests that endocytosis and endolysosomal processing of immunoglobin LCs by host cells is essential to the formation of amyloid fibrils that are deposited in at least some tissues. The aim of this study was to elucidate the role of vascular smooth muscle in amyloid angiopathy.

METHODS

Human coronary artery smooth muscle cells (SMCs) were grown on coverslips, four chamber glass slides, and growth factor-reduced Matrigel matrix in the presence of 10 µg/ml of ALs (λ and κ isotypes), nonamyloidogenic LCs, and culture medium (negative control) for 48 and 72 hours. Thereafter, a detailed light microscopic, immunohistochemical, and ultrastructural evaluation was conducted to verify amyloid deposition and characterize the role of SMCs in the formation of amyloid deposits in the various experimental conditions.

RESULTS

Amyloid deposits were detected extracellulary as early as 48 hours after exposure of vascular smooth muscle cells (VSMCs) to AL-LCs (amyloidogenic light chains) as confirmed by affinity to Congo red dye, thioflavin T fluorescence, and transmission electron microscopy. No amyloid was present in the cultures of SMCs treated with medium alone or nonamyloidogenic LCs. SMCs associated with amyloid deposits exhibited CD68, lysosome-associated membrane protein 1-1, and intracellular lambda light chain expression and only focal smooth muscle actin and muscle-specific actin positivity. Electron microscopy revealed these cells to have an expanded mature lysosomal compartment closely associated with deposits of newly formed amyloid fibrils.

CONCLUSIONS

The interaction of amyloidogenic LCs with VSMCs is necessary for the formation of amyloid fibrils that are deposited in peripheral vessels. VSMCs participate in the formation of amyloid by the intracellular processing of AL-LCs, which is possible due to their transformation from a smooth muscle to a macrophage phenotype. The formation of amyloid fibrils occurs in the mature lysosomal compartment of transformed cells. The amyloid that is formed is then extruded into the extracellular matrix.

Clinical outcomes and survival in AA amyloidosis patients

AIM

Amyloid A amyloidosis is a rare complication of chronic inflammatory conditions. Most patients with amyloid A amyloidosis present with nephropathy and it leads to renal failure and death. We studied clinical characteristics and survival in patients with amyloid A amyloidosis.

METHODS

A total of 81 patients (51 males, 30 females) with renal biopsy proven amyloid A amyloidosis were analyzed retrospectively. The patients were divided into good and poor outcomes groups according to survival results.

RESULTS

Most of the patients (55.6%) had nephrotic range proteinuria at diagnosis. Most frequent underlying disorders were familial Mediterranean fever (21.2%) and rheumatoid arthritis (10.6%) in the good outcome group and malignancy (20%) in the poor outcome group. Only diastolic blood pressure in the good outcome group and phosphorus level in the poor outcome group was higher. Serum creatinine levels increased after treatment in both groups, while proteinuria in the good outcome group decreased. Increase in serum creatinine and decrease in estimated glomerular filtration rate of the poor outcome group were more significant in the good outcome group. At the time of diagnosis 18.5% and 27.2% of all patients had advanced chronic kidney disease (stage 4 and 5, respectively). Median duration of renal survival was 65±3.54 months. Among all patients, 27.1% were started dialysis treatment during the follow-up period and 7.4% of all patients underwent kidney transplantation. Higher levels of systolic blood pressure [hazard ratios 1.03, 95% confidence interval: 1-1.06, p=0.036], serum creatinine (hazard ratios 1.25, 95% confidence interval: 1.07-1.46, p=0.006) and urinary protein excretion (hazard ratios 1.08, 95% confidence interval: 1.01-1.16, p=0.027) were predictors of end-stage renal disease. Median survival of patients with organ involvement was 50.3±16 months.

CONCLUSION

Our study indicated that familial Mediterranean fever constituted a large proportion of cases and increased number of patients with idiopathic amyloid A amyloidosis. Additionally, it was observed that patient survival was not affected by different etiological causes in amyloid A amyloidosis.

Clinical Presentation of Tubulointerstitial Nephritis Caused by Amyloid Light-chain Amyloidosis in a Patient with Sjögren's Syndrome

We report a 70-year-old woman with Sjögren's syndrome who had severe renal dysfunction with mild proteinuria and elevated urinary low-molecular-weight proteins. Based on these clinical presentations, interstitial nephritis due to Sjögren's syndrome was strongly suspected. Unexpectedly, renal pathology revealed amyloid light-chain (AL) lambda-type depositions predominantly in the vasculatures with severe tubulointerstitial damage. Concentrated urine immunofixation was positive for Bence Jones lambda-type monoclonal proteins. Given the involvement in other organs, systemic AL amyloidosis was diagnosed. The patient underwent chemotherapy, but hemodialysis was ultimately instituted. It should be remembered that renal amyloidosis occurs as a clinical presentation of interstitial nephritis.

[Causes and treatment of systemic amyloidosis]

BACKGROUND

Systemic amyloidoses are rare protein deposition disorders, which are often diagnosed in an advanced stage of the disease due to non-specific symptoms. Any chronic inflammatory disease can lead to an AA-type amyloidosis.

AIM

This paper summarizes the current state of the art of diagnosis and treatment of AA amyloidosis and presents data from the past 10 years of our amyloidosis center.

MATERIAL AND METHODS

Our data represents an analysis of our cohort of patients with amyloidosis and a selective research in the PubMed database for AA amyloidosis.

RESULTS

The underlying diseases comprise autoinflammatory syndromes, polyarthritis, and chronic inflammatory bowel and lung diseases. Renal organ involvement is the most prevalent in AA amyloidosis. It can be detected early through the evaluation of proteinuria. The treatment depends on the individual underlying disease. Patients without an associated inflammatory disease are considered to have idiopathic AA amyloidosis and empiric treatment is mandatory.

DISCUSSION

Survival of this fatal disease has recently improved due to the new diagnostic tools and treatment options; however, early diagnosis plays a crucial role in the prevention of end-stage renal failure. New therapeutic strategies aim to remove existing amyloid deposits.

Deposition, Clearance, and Reinduction of Amyloid A Amyloid in Interleukin 1 Receptor Antagonist Knockout Mice

Amyloid A (AA) amyloidosis is characterized by the extracellular deposition of AA amyloid and results in the irreversible dysfunction of parenchymal organs. In experimental models, AA amyloid deposits are cleared following a decrease in circulating serum amyloid A (SAA) concentrations. Additional inflammatory stimuli during this recovery process may induce more severe amyloid redeposition. In the present study, we confirmed the deposition, clearance, and reinduction of AA amyloid deposits in interleukin 1 receptor antagonist knockout mice (IL-1raKO) and studied the SAA levels and amyloid-enhancing factor activity based on the time-dependent changes of amyloid deposition. Histopathologically, following initial (day 0) injection of amyloid-enhancing factor in combination with an inflammatory stimulus (silver nitrate [AgNO₃]), amyloid deposition peaked by day 20, and its deposition gradually decreased after day 35. SAA concentrations in serum were precipitously elevated on day 1 but returned to normal levels by day 10, whereas the SAA dimer was detected in serum after day 45. An additional AgNO₃ injection was administered to mice with amyloidosis on day 5, 10, 35, or 50, and all mice developed large amyloid deposits. Amyloid deposition was most severe in mice treated with AgNO₃ on day 35. The inoculation of sera from mice with AA amyloidosis, combined with AgNO₃, induced AA amyloidosis. Serum samples collected on days 35 and 50, which contained high concentrations of the SAA dimer, induced amyloidosis in a high proportion (83%) of mice. Therefore, increased SAA and/or its dimer in serum during the recovery process may markedly exacerbate the development of AA amyloidosis.

Long-term prognosis of AL and AA renal amyloidosis: a Japanese single-center experience

BACKGROUND

Few studies have been conducted on the long-term prognosis of patients with amyloid light chain (AL) and amyloid A (AA) renal amyloidosis in the same cohort.

METHODS

We retrospectively examined 68 patients with biopsy-proven renal amyloidosis (38 AL and 30 AA). Clinicopathological findings at the diagnosis and follow-up data were evaluated in each patient. We analyzed the relationship between clinicopathological parameters and survival data.

RESULTS

Significant differences were observed in several clinicopathological features, such as proteinuria levels, between the AL and AA groups. Among all patients, 84.2 % of the AL group and 93.3 % of the AA group received treatments for the underlying diseases of amyloidosis. During the follow-up period (median 18 months in AL and 61 months in AA), 36.8 % of the AL group and 36.7 % of the AA group developed end-stage renal failure requiring dialysis, while 71.1 % of the AL group and 56.7 % of the AA group died. Patient and renal survivals were significantly longer in the AA group than in the AL group. eGFR of >60 mL/min/1.73 m² at biopsy and an early histological stage of glomerular amyloid deposition were identified as low-risk factors. A multivariate analysis showed that cardiac amyloidosis and steroid therapy significantly influenced patient and renal survivals.

CONCLUSIONS

Our results showed that heart involvement was the major predictor of poor outcomes in renal amyloidosis, and that the prognosis of AA renal amyloidosis was markedly better than that in previously reported cohorts. Therapeutic advances in inflammatory diseases are expected to improve the prognosis of AA amyloidosis.

Proteomics and mass spectrometry in the diagnosis of renal amyloidosis

The amyloidoses are a ‘group’ of disorders, all of which are associated with deposits that display similar staining and ultrastructural features and are toxic to tissues. Many proteins—currently 31 protein types and many more variants—have been shown to undergo such transformations. Among the various currently known amyloidoses, there are marked differences with regard to their pathogenesis and incidence, while the associated clinical picture is frequently overlapping. However, the therapies that are currently available are amyloid-type specific. The diagnosis of amyloidosis thus involves two steps: (i) a generic diagnosis, followed by (ii) an amyloid type-specific diagnosis or ‘amyloid typing’. Immunofluorescence in frozen sections or immunohistochemistry (IHC) in paraffin sections has traditionally been used in the typing of amyloid. However, IHC of amyloid differs significantly from IHC in other areas of surgical pathology; both caution and experience are necessary for its interpretation. The rationale for the application of proteomic methods to amyloid typing lies in the relative abundance of amyloid proteins in tissue where, frequently, it is the ‘dominant’ protein. Proteomic techniques include the following steps: sample preparation, protein extraction and digestion into peptide fragments, followed by their subsequent separation and measurement by mass spectrometry (MS) and protein identification by informatics. The advantages as well as the limitations of both methods—immunohistochemistry and MS-based proteomics—are discussed. The current recommendations for the application of proteomics in renal amyloidosis are summarized.

Renal involvement in monoclonal gammopathy

Monoclonal gammopathy is produced by neoplastic or non-neoplastic expansion of a clone of plasma cells or B lymphocytes. Monoclonal gammopathy of unknown significance is characterized by low levels of the monoclonal protein and a relatively small population of clonal lymphocytes or plasma cells in the bone marrow. In these cases, the patient is asymptomatic with no evidence of overt myeloma or lymphoma. The abnormal serum protein may be present as a complete immunoglobulin molecule or may consist of ≥1 of its components such as light chains or heavy chains. These proteins may cause a variety of diseases in various tissues and organs, of which the kidney appears to be the most vulnerable. Renal involvement in monoclonal gammopathy may occur as part of a generalized disease such as amyloidosis, immunoglobulin deposition disease, and cryoglobulinemia. In addition, there may be evidence of kidney damage by processes which are renal specific. These include light chain proximal tubulopathy, light chain cast nephropathy, and a variety of glomerulopathies encompassing a wide spectrum of disease patterns.

Percentage of urinary albumin excretion and serum-free light-chain reduction are important determinants of renal response in myeloma patients with moderate to severe renal impairment

Reversal of renal dysfunction significantly affects the prognosis of multiple myeloma (MM) with renal impairment (RI). There is no reliable test for predicting reversibility of RI in MM patients. We postulated that MM with high albuminuria may reflect glomerular disease that is difficult to reverse. Here, we examined the impact of urinary albumin excretion. We retrospectively analyzed 279 patients admitted to our hospital from April 2000 to December 2013. Clinical variables and laboratory data that may affect myeloma treatment response were extracted. The results were examined for relationship to renal response by univariate and multivariate analysis. RI (estimated glomerular filtration rate ≦50 ml/min per 1.73 m(2)) was observed in 116 patients (46%) and renal responses of renal complete response, renal partial response, renal minor response and no response were obtained in 46 (40%), 15 (13%), 13 (11%) and 42 (36%) patients, respectively. Although renal recovery was significantly associated with Durie-Salmon 1 or 2 (P=0.02), myeloma response better than very good partial response (P=0.03), involved free light-chain (iFLC) reduction from baseline 80% at day 12 (P=0.005), ≧95% at day 21 (P<0.001) and urinary albumin ≦25% on admission (P<0.001) on univariate analysis, only reduction of iFLC 95% at day 21 (P=0.015) and urinary albumin ≦25% (P=0.007) remained significant for any renal response. Our observation indicates that increased urinary albumin excretion >25% and reduction of iFLC ≦95% on day 21 were associated with favorable renal recovery in MM patients with RI, and were considered as negative predictors for renal response.

Renal Amyloidosis

Amyloidosis is an uncommon group of diseases in which soluble proteins aggregate and deposit extracellularly in tissue as insoluble fibrils, leading to tissue destruction and progressive organ dysfunction. More than 25 proteins have been identified as amyloid precursor proteins. Amyloid fibrils have a characteristic appearance on ultrastructural examination and generate anomalous colors under polarized light. Amyloidosis can be systemic or localized. The kidney is a prime site for amyloid deposition. Immunofluorescence, immunoperoxidase, and more recently laser microdissection and mass spectrometry are important tools used in the typing of renal amyloidosis.

Distribution of amyloid deposits in the kidneys of a patient with reactive amyloidosis associated with rheumatoid arthritis

Background

We previously reported that the amount of amyloid A (AA) amyloid deposited in renal biopsy specimens was highly correlated with parameters of renal function. However, the distribution of amyloid deposits throughout the kidneys of these patients, and the degree of renal abnormality, remained unclear. Therefore, we describe the features of reactive amyloidosis associated with rheumatoid arthritis (RA) in an autopsied patient.

Case presentation

The present report case is a 50-year-old female with RA and reactive amyloidosis. She was diagnosed as RA in 1978. Diagnosis of AA amylodosis was made by renal biopsy in 1991 for the reason of proteinuria. Because of the pancreatitis, she was died in 2006 and autopsy was performed. Renal tissues from autopsy specimens were evaluated for their proportions of amyloid-positive areas. A total of 6 specimens (three tissue blocks from each kidney obtained at autopsy) were evaluated in this study. The size of each block was approximately 20 mm × 20 mm. One section of whole tissue was photographed in each case. The borders of the amyloid-positive areas in each specimen were traced in each photograph, excluding any tissue-free spaces. The total amyloid-positive area was measured, and the percentage area of amyloid per whole-tissue section (percent (%) area of amyloid deposition) was calculated. The distribution of amyloid deposits in the kidneys was examined. The significance of differences in the mean percent (%) area of amyloid deposition between the right and left sides and among three long-axis levels (upper, middle and lower) were analyzed by two-way analysis of variance (ANOVA) at a significance level of p <0.05.

Conclusion

The area of amyloid deposition in these samples was about 7-11%, and the degree of variability among them seemed to be small. It also shows a comparison of amyloid deposition between the right and left sides and between the long axis samples for quadruplicate determinations; no significant differences were evident, and thus the percent (%) area of amyloid deposition throughout the whole kidneys appeared to be uniform in this patient.

Spectrum of nontumoral renal pathologies in tumor nephrectomies: nontumoral renal parenchyma changes

Non-neoplastic changes are not rarely seen in renal parenchyma of nephrectomy specimens removed for primary renal neoplasms. These changes often involve both kidneys, thus causing impairment of renal function, reducing patient's quality of life and sometimes threatening it. Renal tissue accompanying the tumor provides an opportunity in order to evaluate these changes. However, the clinician should make available clinical and laboratory findings involving renal functions of the patient to the pathologist. It is also important that the pathologist must have appropriate knowledge and experience in nephropathology. In this study, we aimed to correlate these changes with the clinical data and make inquiries regarding our experience with nonneoplastic kidney pathology. Consecutive 403 nephrectomy specimens with primary renal neoplasms submitted to our department between 2003 and 2009 were re-examined. Twenty-three nephrectomy materials from 21 patients had non-neoplastic changes, 2 of which were bilateral. Patient follow-up data were obtained from electronic medical records. Of all cases, eight had diabetic nephropathy; 2, amyloidosis; 5, segmental proliferative and/or sclerotic glomerulonephritis; and 6, cystic renal changes. These findings were seen in 5% of nephrectomy specimens diagnosed as clear cell renal cell carcinoma (RCC), chromophobe cell RCC and oncocytoma, whereas this rate was two times higher in nephrectomy specimens with papillary RCC. Most patients with renal failure who were diagnosed with clear cell carcinoma died within the first two years. Despite limited number of cases in our series, prognosis of cases with clear cell RCC were poorer. Consequently, we think that non-neoplastic changes should be reported along with the details regarding the tumor in order to achieve best treatment planning.

Anesthetic modulation of neuroinflammation in Alzheimer's disease

PURPOSE OF REVIEW

To summarize key studies and recent thought on the role of neuroinflammation in chronic neurodegeneration, and whether it can be modulated by anesthesia and surgery.

RECENT FINDINGS

A large and growing body of evidence shows that neuroinflammation participates in the development of neurodegeneration associated with Alzheimer's disease. Modulation may be possible early in the pathogenesis, and less so when cognitive symptoms appear. A dysfunctional hypoinflammatory response may permit accelerated damage due to other mechanisms in late disease. The peripheral inflammatory response elicited by surgery itself appears to provoke a muted neuroinflammatory response, which enhances ongoing neurodegeneration in some models. Anesthetics have both anti-inflammatory and proinflammatory effects depending on the drug and concentration, but in general, appear to play a small role in neuroinflammation. Human studies at the intersection of chronic neurodegeneration, neuroinflammation, and surgery/anesthesia are rare.

SUMMARY

The perioperative period has the potential to modulate the progression of chronic neurodegenerative diseases. The growing number of elderly having surgery, combined with the expanding life expectancy, indicates the potential for this interaction to have considerable public health implications, and call for further research, especially in humans.

Concurrent nephrotic syndrome and acute renal failure caused by chronic lymphocytic leukemia (CLL): a case report and literature review

Kidney injury associated with lymphocytic leukemia (CLL) is typically caused by direct tumor infiltration which occasionally results in acute renal failure. Glomerular involvement presenting as proteinuria or even nephrotic syndrome is exceptionally rare. Here we report a case of 54-year-old male CLL patient with nephrotic syndrome and renal failure. The lymph node biopsy confirmed that the patients had CLL with remarkable immunoglobulin light chain amyloid deposition. The renal biopsy demonstrated the concurrence of AL amyloidosis and neoplastic infiltration. Combined treatment of fludarabine, cyclophosphamide and rituximab resulted in remission of CLL, as well as the renal disfunction and nephrotic syndrome, without recurrence during a 12-month follow-up. To our knowledge, this is the first case of CLL patient showing the nephrotic syndrome and acute renal failure caused by AL amyloidosis and neoplastic infiltration. Though AL amyloidosis caused by plasma cell dyscrasia usually responses poorly to chemotherapy, this patient exhibited a satisfactory clinical outcome due to successful inhibition of the production of amylodogenic light chains by combined chemotherapy.