Amyloid storm: acute kidney injury and massive proteinuria, rapidly progressing to end-stage kidney disease in AA amyloidosis of familial Mediterranean fever

AA Amyloidosis: A Contemporary View

PURPOSE OF REVIEW

Amyloid A (AA) amyloidosis is an organ- or life-threatening complication of chronic inflammatory disorders. Here, we review the epidemiology, causes, pathogenesis, clinical features, and diagnostic and therapeutic strategies of AA amyloidosis.

RECENT FINDINGS

The incidence of AA amyloidosis has declined due to better treatment of the underlying diseases. Histopathological examination is the gold standard of diagnosis, but magnetic resonance imaging can be used to detect cardiac involvement. There is yet no treatment option for the clearance of amyloid fibril deposits; therefore, the management strategy primarily aims to reduce serum amyloid A protein. Anti-inflammatory biologic agents have drastically expanded our therapeutic armamentarium. Kidney transplantation is preferred in patients with kidney failure, and the recurrence of amyloidosis in the allograft has become rare as transplant recipients have started to benefit from the new agents. The management of AA amyloidosis has been considerably changed over the recent years due to the novel therapeutic options aiming to control inflammatory activity. New agents capable of clearing amyloid deposits from the tissues are still needed.

Novel photocatalytic carbon dots: efficiently inhibiting amyloid aggregation and quickly disaggregating amyloid aggregates

Amyloid aggregation is implicated in the pathogenesis of various neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). It is critical to develop high-performance drugs to combat amyloid-related diseases. Most identified nanomaterials exhibit limited biocompatibility and therapeutic efficacy. In this work, we used a solvent-free carbonization process to prepare new photo-responsive carbon nanodots (CNDs). The surface of the CNDs is densely packed with chemical groups. CNDs with large, conjugated domains can interact with proteins through π-π stacking and hydrophobic interactions. Furthermore, CNDs possess the ability to generate singlet oxygen species (1O2) and can be used to oxidize amyloid. The hydrophobic interaction and photo-oxidation can both influence amyloid aggregation and disaggregation. Thioflavin T (ThT) fluorescence analysis and circular dichroism (CD) spectroscopy indicate that CNDs can block the transition of amyloid from an α-helix structure to a β-sheet structure. CNDs demonstrate efficacy in alleviating cytotoxicity induced by Aβ42 and exhibit promising blood-brain barrier (BBB) permeability. CNDs have small size, low biotoxicity, good fluorescence and photocatalytic properties, and provide new ideas for the diagnosis and treatment of amyloid-related diseases.

Characteristics and course of patients with AA amyloidosis: single centre experience with 174 patients from Turkey

OBJECTIVES

This study aimed to evaluate the clinical, laboratory and genetic characteristics and outcomes of patients with AA amyloidosis.

METHODS

Patients followed up in a tertiary referral centre in Turkey with the diagnosis of inflammatory rheumatic diseases and immunohistologically proven AA amyloidosis were included in the study and retrospectively analysed.

RESULTS

Among 184 patients with the diagnosis of AA amyloidosis, 174 (83 female, 91 male) were included in the analysis. The most common cause of AA amyloidosis was FMF (78.7%), and 91% of FMF-AA amyloidosis patients were carrying the p.M694V variant (74.1% homozygous). AA amyloidosis was identified earlier in patients with homozygous or compound heterozygous MEFV exon 10 variants compared with the heterozygous patients (27, 30 and 41 years, respectively). Patients with an estimated glomerular filtration rate <60 ml/min at admission had a higher frequency of progression to end-stage renal disease (P < 0.001). The overall mortality rate was 15.3% and it increased gradually in association with the amyloid burden (10% in patients with renal, 15% in renal + gastrointestinal and 43% in those with additional cardiac involvement). Renal findings responded completely to treatment in 31% of the patients, a partial response was observed in 4%, a stable course in 23.6% and progression in 38.5%. Amyloid storm was identified in nine patients and was found to be associated with increased mortality within 1 year.

CONCLUSION

FMF patients still constitute the majority of AA amyloidosis patients in Turkey. The MEFV genotype and associated inflammatory load may affect the age of onset of AA amyloidosis, and earlier diagnosis and stricter follow-up and treatment may delay progression of the disease.

A review: Exploring the metabolic and structural characterisation of beta pleated amyloid fibril in human tissue using Raman spectrometry and SAXS

Amyloidosis is a deleterious condition caused by abnormal amyloid fibril build-up in living tissues. To date, 42 proteins that are linked to amyloid fibrils have been discovered. Amyloid fibril structure variation can affect the severity, progression rate, or clinical symptoms of amyloidosis. Since amyloid fibril build-up is the primary pathological basis for various neurodegenerative illnesses, characterization of these deadly proteins, particularly utilising optical techniques have been a focus. Spectroscopy techniques provide significant non-invasive platforms for the investigation of the structure and conformation of amyloid fibrils, offering a wide spectrum of analyses ranging from nanometric to micrometric size scales. Even though this area of study has been intensively explored, there still remain aspects of amyloid fibrillization that are not fully known, a matter hindering progress in treating and curing amyloidosis. This review aims to provide recent updates and comprehensive information on optical techniques for metabolic and proteomic characterization of β-pleated amyloid fibrils found in human tissue with thorough literature analysis of publications. Raman spectroscopy and SAXS are well established experimental methods for study of structural properties of biomaterials. With suitable models, they offer extended information for valid proteomic analysis under physiologically relevant conditions. This review points to evidence that despite limitations, these techniques are able to provide for the necessary output and proteomics indication in order to extrapolate the aetiology of amyloid fibrils for reliable diagnostic purposes. Our metabolic database may also contribute to elucidating the nature and function of the amyloid proteome in development and clearance of amyloid diseases.

Serum Amyloid A Protein–Associated Kidney Disease: Presentation, Diagnosis, and Management

Serum amyloid A protein (AA) amyloidosis, also known as secondary amyloidosis, is a known consequence of chronic inflammation and results from several conditions including inflammatory arthritis, periodic fever syndromes, and chronic infection. AA amyloidosis can lead to multiorgan dysfunction, including changes in glomerular filtration rate and proteinuria. Definitive diagnosis requires tissue biopsy, and management of AA amyloid kidney disease is primarily focused on treating the underlying inflammatory condition to stabilize glomerular filtration rate, reduce proteinuria, and slow potential progression to kidney failure. In this narrative review, we describe the causes, pathophysiology, presentation, and pathologic diagnosis of AA amyloid kidney disease using an illustrative case of biopsy-proven AA amyloid kidney disease in a patient with long-standing rheumatoid arthritis who had a favorable response to interleukin 6 inhibition. We conclude the review with a description of established and more novel therapies for AA amyloidosis including published cases of use of tocilizumab (an interleukin 6 inhibitor) in biopsy-proven AA amyloid kidney disease.

COVID-19 in Familial Mediterranean Fever: Clinical Course and Complications Related to Primary Disease

Objectives

To evaluate the impact of familial Mediterranean fever (FMF) features on the clinical course and outcomes of coronavirus disease 2019 (COVID-19) and clinical course of FMF after COVID-19.

Methods

Consecutive FMF patients with COVID-19 were enrolled from three referral hospitals. Clinical features of FMF and detailed COVID-19 information were obtained from patient interviews and medical records.

Results

Seventy-three FMF patients were included in the study. 94.5% of patients had clinical symptoms of COVID-19. We found 24.7% hospitalization, 12.3% respiratory support, 4.1% intensive care unit admission, 6.8% complication, and 1.4% mortality rate in patients. The risk factors of hospitalization for respiratory support were male gender [OR: 7.167 (95% CI: 1.368–37.535)], greater age [OR: 1.067 (95% CI: 1.016–1.121)], and non-adherence to colchicine treatment before the infection [OR: 7.5 (95% CI: 1.348–41.722)]. One-third of patients had reported attacks after COVID-19. The patterns of triggered attacks were fever, peritonitis, pleuritis, transient arthritis, chronic knee mono-arthritis, and protracted febrile myalgia.

Conclusions

FMF characteristics were not associated with worse outcomes of COVID-19. Colchicine non-adherence was the risk factor of hospitalization for oxygen support. The rate of FMF attacks after COVID-19 is prominently increased, with some of them being protracted and destructive.

Dismal Prognosis of Acute Allergic Tubulointerstitial Nephritis in Patients with AA Amyloidosis

INTRODUCTION

Patients with AA amyloidosis may present with acute kidney injury that progresses to end-stage kidney disease in a short period of time. Acute allergic tubulointerstitial nephritis (aTIN) is a frequent cause of acute kidney injury in patients with AA amyloidosis. Although aTIN has a favorable prognosis in the general population, the course of aTIN in patients with AA amyloidosis was not previously reported. In this retrospective study, we determined the prognosis of aTIN superimposed on AA amyloidosis.

METHODS

Thirty-two patients with combined pathological diagnosis of AA amyloidosis + aTIN and 32 patients with isolated aTIN were compared in terms of 1-year renal functions after the biopsies were performed with an indication of acute kidney injury. Baseline renal functions and number of patients requiring hemodialysis at the time of biopsy was similar in both groups.

RESULTS

At the end of the 12-month follow-up period, 29 of 32 patients in the amyloidosis + aTIN group and 1 of 32 patients in the isolated aTIN group required dialysis. Most of these patients with AA amyloidosis had completely normal renal function before the episode of acute kidney injury and had clear exposures to drugs associated with aTIN.

CONCLUSION

In contrary to the patients without AA amyloidosis, patients with AA amyloidosis have extremely high risk of permanent renal failure in case of development of aTIN. Great caution should be exercised in prescribing drugs that are associated with aTIN, in patients with AA amyloidosis.

Amyloidosis and Glomerular Diseases in Familial Mediterranean Fever

Familial Mediterranean fever (FMF) is a genetic autoinflammatory disease with autosomal recessive transmission, characterized by periodic fever attacks with self-limited serositis. Secondary amyloidosis due to amyloid A renal deposition represents the most fearsome complication in up to 8.6% of patients. Amyloidosis A typically reveals a nephrotic syndrome with a rapid progression to end-stage kidney disease still. It may also involve the cardiovascular system, the gastrointestinal tract and the central nervous system. Other glomerulonephritis may equally affect FMF patients, including vasculitis such as IgA vasculitis and polyarteritis nodosa. A differential diagnosis among different primary and secondary causes of nephrotic syndrome is mandatory to determine the right therapeutic choice for the patients. Early detection of microalbuminuria is the first signal of kidney impairment in FMF, but new markers such as Neutrophil Gelatinase-Associated Lipocalin (NGAL) may radically change renal outcomes. Serum amyloid A protein (SAA) is currently considered a reliable indicator of subclinical inflammation and compliance to therapy. According to new evidence, SAA may also have an active pathogenic role in the regulation of NALP3 inflammasome activity as well as being a predictor of the clinical course of AA amyloidosis. Beyond colchicine, new monoclonal antibodies such as IL-1 inhibitors anakinra and canakinumab, and anti-IL-6 tocilizumab may represent a key in optimizing FMF treatment and prevention or control of AA amyloidosis.