Systemic AA amyloidosis: epidemiology, diagnosis, and management

Amyloidosis and Amyloidogenesis: One Name, Many Diseases

Amyloidosis is a heterogenous group of disorders, caused by the deposition of insoluble fibrils derived from misfolded proteins in the extracellular space of various organs. These proteins have an unstable structure that causes them to misfold, aggregate, and deposit as amyloid fibrils with the pathognomonic histologic property of green birefringence when viewed under cross-polarized light after staining with Congo red. Amyloid fibrils are insoluble and degradation-resistant; resistance to catabolism results in progressive tissue amyloid accumulation. The outcome of this process is organ disfunction independently from the type of deposited protein, however there can be organ that are specifically targeted from certain proteins.

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.

Secondary amyloidosis in inflammatory bowel disease patients: findings from three tertiary medical centers

Secondary amyloidosis (AA) is a disorder of protein conformation associated with inflammatory disorders. Detailed reports of patients diagnosed with AA and inflammatory bowel disease (IBD) are limited. This study reports the cases of eight patients, across three tertiary medical centers, diagnosed with both IBD and AA between 2000 and 2020. Seven patients had a diagnosis of Crohn disease (CD), while one had ulcerative colitis (UC). All patients were diagnosed with AA after being diagnosed with IBD (median: 15 years later). The small bowel (62.5%) and the colon (62.5%) were the most common IBD locations. 4 patients had undergone TNF-alpha inhibitor therapy and all CD patients required surgical treatment of their IBD. A history of fistula or abscess was identified in 5 patients. The most common initial site of AA was the kidney (75%). All 8 patients presented with some form of renal dysfunction and proteinuria (median: 1500 mg/24 h). Hypoalbuminemia was found in most patients. Six patients developed chronic kidney disease and 4 required dialysis. Anti TNF-alpha antibody therapy led to rapid improvement of renal function in one of four patients who received it. Three patients required a renal transplant. Four patients had died upon the latest follow-up (5-year survival: 75%). The presence of proteinuria, fistula, or abscess should serve as indicators for potentially increased AA risk in CD patients.

The Promising Role of Selenium and Yeast in the Fight Against Protein Amyloidosis

In recent years, increasing attention has been paid to research on diseases related to the deposition of misfolded proteins (amyloids) in various organs. Moreover, modern scientists emphasise the importance of selenium as a bioelement necessary for the proper functioning of living organisms. The inorganic form of selenium-sodium selenite (redox-active)-can prevent the formation of an insoluble polymer in proteins. It is very important to undertake tasks aimed at understanding the mechanisms of action of this element in inhibiting the formation of various types of amyloid. Furthermore, yeast cells play an important role in this matter as a eukaryotic model organism, which is intensively used in molecular research on protein amyloidosis. Due to the lack of appropriate treatment in the general population, the problem of amyloidosis remains unsolved. This extracellular accumulation of amyloid is one of the main factors responsible for the occurrence of Alzheimer's disease. The review presented here contains scientific information discussing a brief description of the possibility of amyloid formation in cells and the use of selenium as a factor preventing the formation of these protein aggregates. Recent studies have shown that the yeast model can be successfully used as a eukaryotic organism in biotechnological research aimed at understanding the essence of the entire amyloidosis process. Understanding the mechanisms that regulate the reaction of yeast to selenium and the phenomenon of amyloidosis is important in the aetiology and pathogenesis of various disease states. Therefore, it is imperative to conduct further research and analysis aimed at explaining and confirming the role of selenium in the processes of protein misfolding disorders. The rest of the article discusses the characteristics of food protein amyloidosis and their use in the food industry. During such tests, their toxicity is checked because not all food proteins can produce amyloid that is toxic to cells. It should also be noted that a moderate diet is beneficial for the corresponding disease relief caused by amyloidosis.

bDMARD can prevent the progression of AA amyloidosis to end-stage renal disease

INTRODUCTION

AA amyloidosis (AA) can be the consequence of any chronic inflammatory disease. AA is associated with chronic inflammatory diseases (cid+AA), autoinflammatory syndromes (auto+AA) or AA of unknown origin or idiopathic AA (idio+AA). The major organ manifestation is renal AA that can progress to end-stage renal disease (ESRD) and multiple organ failure.

MATERIALS AND METHODS

This study is a monocentric retrospective analysis of the renal outcome and survival of patients with cid+AA (n=34), auto+AA (n=24) and idio+AA (n=25) who were treated with cytokine-inhibiting biological disease-modifying antirheumatic drugs (bDMARDs).

RESULTS

83 patients with renal AA were identified and followed for a mean observational period of 4.82 years. C reactive protein (CRP), serum amyloid alpha and proteinuria were significantly reduced with bDMARD therapy. Progression to ESRD was prevented in 60% (cid+AA), 88% (auto+AA) and 81% (idio+AA) of patients. Tocilizumab was given to 34 patients with cid+AA and idio+AA and was more effective in reducing CRP and progression to ESRD and death compared with other bDMARDs.

CONCLUSIONS

bDMARDs reduce systemic inflammation in various diseases, leading to a reduction of proteinuria and prevention of ESRD. Importantly, tocilizumab was more effective than other bDMARDs in controlling systemic inflammation in patients with chronic inflammatory diseases and idiopathic AA, leading to better renal and overall survival.

Systemic Amyloid A Protein Amyloidosis With Gastrointestinal Involvement

Systemic amyloidosis is a multiorgan deposition of misfolded amyloid protein fibrils. The systemic amyloid A protein (AA) amyloidosis type predominantly involves the kidney and is mostly an under-recognized complication among persons who inject drugs. Gastrointestinal involvement in systemic AA amyloidosis that is associated with illicit drug use is uncommon. In this report, we present a case of a 40-year-old man with history of injection drug use, recurrent skin and soft-tissue infection, and renal AA amyloidosis that presented with painless bloody bowel movement, which initially resolved with conservative management. Upon further evaluation, the patient was found to have empyema that required antibiotic therapy and bilateral pleural drain. His hospital course was further complicated by multiple episodes of hematochezia requiring gastrointestinal consultation. Subsequent gastrointestinal biopsy revealed amyloid deposit.

Amyloid fibril cytotoxicity and associated disorders

Misfolded proteins assemble into fibril structures that are called amyloids. Unlike usually folded proteins, misfolded fibrils are insoluble and deposit extracellularly or intracellularly. Misfolded proteins interrupt the function and structure of cells and cause amyloid disease. There is increasing evidence that the most pernicious species are oligomers. Misfolded proteins disrupt cell function and cause cytotoxicity by calcium imbalance, mitochondrial dysfunction, and intracellular reactive oxygen species. Despite profound impacts on health, social, and economic factors, amyloid diseases remain untreatable. To develop new therapeutics and to understand the pathological manifestations of amyloidosis, research into the origin and pathology of amyloidosis is urgently needed. This chapter describes the basic concept of amyloid disease and the function of atypical amyloid deposits in them.

Myocardial Calcification: An Unusual Complication of Remote Trauma With Coidentified Amyloidosis

We present the heart of a 38-year-old man with paraplegia due to a remote traumatic spinal cord injury. In the 20 years following his injury, he experienced chronic decubitus ulcers, osteomyelitis, neurogenic bladder, malnutrition, and urinary tract infections. He was admitted to the hospital with septic shock secondary to multiple decubitus ulcers and osteomyelitis and expired after a two-month hospitalization. At autopsy, there was marked replacement of left ventricle and interventricular septal myocardium by gritty, firm, yellow-white tissue. Microscopic examination demonstrated a remote infarct with marked dystrophic calcification and unexpected amyloid deposition. This example demonstrates the extraordinary extent to which dystrophic calcifications can replace myocardium and highlights multiple potential etiologies of myocardial calcifications. Of note, this is the first report documenting myocardial calcification as a complication of remote, non-iatrogenic trauma. The role of the amyloidosis in the development of calcification is unclear, but a contributory effect cannot be excluded.

Adult patient diagnosed with Muckle-Wells syndrome, antiphospholipid syndrome and glomerular haematuria

Muckle-Wells syndrome (MWS) is a genetic periodic fever syndrome characterised by urticaria, fever and malaise starting in childhood with the development of perceptive hearing loss and risk of amyloidosis later in life.Patient A, in his 60s, was referred to a nephrologist because of glomerular haematuria and elevated erythrocyte sedimentation rate. He appeared to have periodic fevers since childhood, skin changes in cold circumstances and progressive deafness since he was 30 years of age. Genetic analysis revealed a pathogenic variant in the NLRP3 gene compatible with MWS. Treatment with anakinra (interleukin 1 antagonist) improved his symptoms, but only mild episodic arthralgia remained. Glomerular erythrocyturia diminished during treatment, supposing a relation between MWS and haematuria.This case report shows that rare genetic fever syndromes starting from early childhood can still be diagnosed in adult patients, with important therapeutic consequences. Symptoms can be relieved and amyloidosis with potential renal failure may be prevented.

Investigation of serum amyloid a within animal species focusing on the 1-25 amino acid region

AA amyloidosis, characterized by the misfolding of serum amyloid A (SAA) protein, is the most common amyloid protein disorder across multiple species. SAA is a positive-acute phase protein synthesized by the liver in response to inflammation or stress, and it normally associates with high-density lipoprotein at its N-terminus. In this study, we focused on the 1-25 amino acid (aa) region of the complete 104 aa SAA sequence to examine the aggregation propensity of AA amyloid. A library comprising eight peptides from different species was assembled for analysis. To access the aggregation propensity of each peptide region, a bioinformatic study was conducted using the algorithm TANGO. Congo red (CR) binding assays, Thioflavin T (ThT) assays, and transmission electron microscopy (TEM) were utilized to evaluate whether the synthesized peptides formed amyloid-like fibrils. All synthetic SAA 1-25 congeners resulted in amyloid-like fibrils formation (per CR and/or ThT staining and TEM detection) at the exception of the ferret SAA1-25 fragment, which generated plaque-like materials by TEM. Ten residues were preserved among SAA 1-25 congeners resulting in amyloid-like fibrils, i.e. F6, E9, A10, G13, D16, M17, A20, Y21, D23, and M24. Amino acid residues highlighted by this study may have a role in increasing the propensity for amyloid-like fibril formation. This study put an emphasis on region 1-25 in the mechanism of SAA1 misfolding.

Therapeutic effects of biological treatments on AA amyloidosis associated with inflammatory bowel disease: a case report and literature review

AA amyloidosis is a rare and significant complication of long-term inflammation that can be caused by a variety of disorders, including inflammatory bowel disease, and is linked to an increased risk of morbidity and mortality. To date, there has been no effective direct treatment, and treatment aims at treating the underlying condition with potent immunosuppression to limit inflammatory activity and, as a result, switch off amyloidogenesis. Theoretically, biological treatment can control AA amyloidosis by inducing and maintaining inflammatory bowel disease remission and inhibiting the synthesis of Serum Amyloid A, which is an acute phase reactant and precursor protein of AA amyloidosis that accumulates in the organs. We report the first case of ustekinumab's therapeutic effect after infliximab's loss of response in AA amyloidosis associated with Crohn's disease. We also conducted a literature review of the therapeutic effect of biological treatment on AA amyloidosis.

Treat-to-target strategies for the management of familial Mediterranean Fever in children

BACKGROUND

The objective of this initiative was to develop a treat-to-target (T2T) approach for the management of patients with Familial Mediterranean Fever (FMF), including the definition of a complex treatment target, and establish strategies that improve patient care and long-term outcome.

METHODS

An initial set of statements as well as a flow chart visualising the proposed concept was developed. To adapt the preliminary statements to the current state of knowledge, a systematic literature search was performed and the modified statements were subject to a Delphi approach. To ensure the applicability of the statements in daily practice, an online survey was conducted among paediatric rheumatologists in Germany. In addition, data from the national AID-NET registry were analysed with respect to therapeutic response.

RESULTS

This T2T initiative yielded a total of 26 statements guiding FMF management with respect to diagnosis, treatment targets, treatment strategies and monitoring. The online survey identified cut-off values for inflammatory markers indicating treatment intensification and appropriate measures in case of colchicine intolerance or non-adherence. The analysis of data derived from the national AID-NET showed that colchicine therapy was successfully terminated in 61% of patients (27 out of 44) with heterozygous MEFV mutations. Multidimensional treatment targets incorporating objective and subjective reported outcome measures were developed. These provide the basis for stratifying patients into the following treatment paths: continue colchicine, persisting attacks / inflammation, colchicine intolerance, persisting arthritis, colchicine reduction and adjustment/reduction of biologics.

CONCLUSIONS

The proposed consensus treatment plan for the management of FMF incorporates multidimensional targets allowing transparent treatment decisions, which will promote personalised disease management and increase adherence to therapy.

Intestinal Reactive Amyloid A (AA) Amyloidosis in a Patient With Multiple Myeloma: A Case Report and Literature Review

Amyloidosis is a rare group of disorders characterized by the extracellular deposition of misfolded protein aggregates that interfere with the function of the tissue affected. In some patients, the presenting symptom of monoclonal gammopathies, such as multiple myeloma, can be a gastrointestinal bleed with a further report of amyloidosis in gastrointestinal samples. In all the cases the pathology report is read as AL (light chain) amyloidosis. We present a case of a 57-year-old male patient with no medical history who debuted with gastrointestinal bleeding. A colonoscopy revealed a colonic ulcer with a pathologic diagnosis of amyloid A (AA) amyloidosis. Further investigation led to the finding of multiple myeloma (MM) with no evidence of systemic amyloidosis. Although there is little evidence in the literature of the association or even causative relationship between multiple myeloma and AA amyloidosis, our case highlights the importance of searching for an underlying monoclonal gammopathy like MM in a patient with a confirmed diagnosis of AA amyloidosis.

Gastroparesis: an under-recognised manifestation of systemic amyloidosis

Gastrointestinal (GI) amyloidosis can be acquired or genetic and is commonly caused by chronic inflammatory illnesses (AA amyloidosis), haematological malignancies (AL amyloidosis) and end-stage renal disease (beta-2 microglobulin amyloidosis). The accumulation of these aberrant proteins disrupts the structures and functions of many organs; the least common of which is the GI tract. GI presentations depend on the type, location and amount of amyloid deposition. Symptoms can range from nausea and vomiting to fatal GI bleeds. Pathological examination of the involved tissue with characteristic green birefringence under polarised light is used to confirm the diagnosis. Patients should be considered for further evaluation to rule out additional organ involvement, notably cardiac and renal. We present a patient with amyloidosis-induced gastroparesis, an under-recognised presentation of systemic amyloidosis in the gastroenterology system.

Inflammation across the spectrum of hypertrophic cardiac phenotypes

The hypertrophic cardiomyopathy phenotype encompasses a heterogeneous spectrum of genetic and acquired diseases characterized by the presence of left ventricular hypertrophy in the absence of abnormal cardiac loading conditions. This "umbrella diagnosis" includes the "classic" hypertrophic cardiomyopathy (HCM), due to sarcomere protein gene mutations, and its phenocopies caused by intra- or extracellular deposits, such as Fabry disease (FD) and cardiac amyloidosis (CA). All these conditions share a wide phenotypic variability which results from the combination of genetic and environmental factors and whose pathogenic mediators are poorly understood so far. Accumulating evidence suggests that inflammation plays a critical role in a broad spectrum of cardiovascular conditions, including cardiomyopathies. Indeed, inflammation can trigger molecular pathways which contribute to cardiomyocyte hypertrophy and dysfunction, extracellular matrix accumulation, and microvascular dysfunction. Growing evidence suggests that systemic inflammation is a possible key pathophysiologic process potentially involved in the pathogenesis of cardiac disease progression, influencing the severity of the phenotype and clinical outcome, including heart failure. In this review, we summarize current knowledge regarding the prevalence, clinical significance, and potential therapeutic implications of inflammation in HCM and two of its most important phenocopies, FD and CA.

Renal AA amyloidosis: presentation, diagnosis, and current therapeutic options: a review

Amyloid A amyloidosis is thought to be the second most common form of systemic amyloidosis behind amyloidosis secondary to monoclonal Ig. It is the result of deposition of insoluble fibrils in the extracellular space of tissues and organs derived from the precursor protein serum amyloid A, an acute phase reactant synthesized excessively in the setting of chronic inflammation. The kidney is the most frequent organ involved. Most patients present with proteinuria and kidney failure. The diagnosis is made through tissue biopsy with involvement of the glomeruli in most cases, but also often of the vessels and the tubulointerstitial compartment. The treatment usually targets the underlying etiology and consists increasingly of blocking the inflammatory cascade of cytokines with interleukin-1 inhibitors, interleukin-6 inhibitors, and tumor necrosis factor-α inhibitors to reduce serum amyloid A protein formation. This strategy has also shown efficacy in cases where an underlying etiology cannot be readily identified and has significantly improved the prognosis of this entity. In addition, there has been increased interest at developing effective therapies able to clear amyloid deposits from tissues, albeit with mitigated results so far.

Amyloid A amyloidosis on medullary sponge kidney in a 28-year-old male with gout: A case report and literature review

Amyloidosis is a large group of diseases that occur through misfolding of extracellular proteins that accumulate in tissues and organs. Gout is the most common inflammatory arthritis worldwide and starts with the crystallization of uric acid within the joints and soft tissues. Although gouty arthritis is accompanied by inflammation, AA amyloidosis is rarely seen in patients with gout. Here we present a case of AA amyloidosis on the medullary sponge kidney in a 28-year-old man with gout. Our case had been diagnosed with gout 3 years previously, and his older brother was also diagnosed with early-onset gout. As a result of the hyperuricemic nephropathy clinic and familial history, a whole gene sequence analysis was performed on the HPRT1 gene and UMOD gene, but no pathogenic changes were detected. Renal ultrasound revealed a bilateral medullary sponge kidney and amyloidosis was detected in the renal needle biopsy performed for the etiology of proteinuria. In our literature review, we found 16 cases in which gout was accompanied by AA amyloidosis. We present a 17th case and compare it with the other 16 cases.

AMYLOIDOSIS IN CAPTIVE EUROPEAN EASTERN BONGO (TRAGELAPHUS EURYCERUS ISAACI): PREVALENCE, PREDICTIVE FACTORS, ORGAN PREDILECTION, AND SERUM AMYLOID A CONCENTRATIONS

Amyloidosis is frequently identified during postmortem examination of captive eastern bongo (Tragelaphus eurycerus isaaci) in the European Endangered Species Programme (EEP). However, its significance and etiopathogenesis are poorly understood. The objective of this study was to investigate the prevalence of amyloidosis within this population and identify potential predictive factors for the presence of disease. Postmortem reports obtained from 24 EEP institutions were analyzed and assessed for evidence of amyloidosis. Seventy-two individuals had histopathological assessment performed after gross postmortem examination and were included in the study. Further histopathological analysis was performed on Congo red-stained slides from 26 individuals, and organ predilection sites were identified. Immunohistochemical analysis was performed in six individuals to identify the type of amyloid present. Serum amyloid A (SAA) analysis was performed on blood samples from 34 individuals, and concentrations in affected and unaffected individuals were compared. Amyloidosis was reported in 26 animals (36%). The association between the presence of amyloidosis and sex, age, or body condition was not statistically significant. However, amyloidosis was not identified in any individuals under the age of 6 yr. The presence of chronic inflammatory conditions was the only statistically significant predictive factor for the presence of amyloidosis (P = 0.03). Chronic inflammatory conditions present included nephritis, enteritis, and pneumonia. The majority of affected animals presented with amyloid deposition in multiple organs, with the liver and kidneys being most commonly affected. Immunohistochemistry confirmed the presence of AA amyloid. The association between the presence of amyloidosis and SAA values measured on a single occasion was not statistically significant. This study identified a high prevalence of amyloidosis within the captive European eastern bongo population associated with chronic inflammatory conditions. Antemortem diagnosis of amyloidosis remains challenging, and this study indicates that SAA protein concentrations are not a reliable indicator for the presence of amyloidosis.

Autoinflammatory manifestations in adult patients

Autoinflammatory diseases represent a family of immune-mediated conditions characterized by the unchecked activation of innate immunity. These conditions share common clinical features such as recurrent fever, inflammatory arthritis, and elevation of acute phase reactants, in the absence of an identified infectious etiology, generally without detectable serum autoantibodies, with variable response to glucocorticoids and in some cases colchicine, which represented the mainstay of treatment until cytokine blockade therapies became available. The first autoinflammatory diseases to be described were monogenic disorders caused by missense mutations in inflammasome components and were recognized predominantly during childhood or early adulthood. However, the progress of genetic analyses and a more detailed immunological phenotyping capacity led to the discovery a wide spectrum of diseases, often becoming manifest or being diagnosed in the adult population. The beneficial role of targeting hyperinflammation via interleukin 1 in complex non-immune-mediated diseases is a field of growing clinical interest. We provide an overview of the autoinflammatory diseases of interest to physicians treating adult patients and to analyze the contribution of hyperinflammation in non-immune-mediated diseases; the result is intended to provide a roadmap to orient scientists and clinicians in this broad area.

Current approaches to the diagnosis and management of amyloidosis

Amyloidosis is a collection of diseases caused by the misfolding of proteins that aggregate into insoluble amyloid fibrils and deposit in tissues. While these fibrils may aggregate to form insignificant localised deposits, they can also accumulate in multiple organs to the extent that amyloidosis can be an immediately life-threatening disease, requiring urgent treatment. Recent advances in diagnostic techniques and therapies are dramatically changing the disease landscape and patient prognosis. Delays in diagnosis and treatment remain the greatest challenge, necessitating physician awareness of the common clinical presentations that suggest amyloidosis. The most common types are transthyretin (ATTR) amyloidosis followed by immunoglobulin light-chain (AL) amyloidosis. While systemic AL amyloidosis was previously considered a death sentence with no effective therapies, significant improvement in patient survival has occurred over the past 2 decades, driven by greater understanding of the disease process, risk-adapted adoption of myeloma therapies such as proteosome inhibitors (bortezomib) and monoclonal antibodies (daratumumab) and improved supportive care. ATTR amyloidosis is an underdiagnosed cause of heart failure. Technetium scintigraphy has made noninvasive diagnosis much easier, and ATTR is now recognised as the most common type of amyloidosis because of the increased identification of age-related ATTR. There are emerging ATTR treatments that slow disease progression, decrease patient hospitalisations and improve patient quality of life and survival. This review aims to update physicians on recent developments in amyloidosis diagnosis and management and to provide a diagnostic and treatment framework to improve the management of patients with all forms of amyloidosis.

Signal peptide stabilizes folding and inhibits misfolding of serum amyloid A

Signal peptide (SP) plays an important role in membrane targeting for insertion of secretory and membrane proteins during translocation processes in prokaryotes and eukaryotes. Beside the targeting functions, SP has also been found to affect the stability and folding of several proteins. Serum amyloid A (SAA) proteins are apolipoproteins responding to acute-phase inflammation. The fibrillization of SAA results in a protein misfolding disease named amyloid A (AA) amyloidosis. The main disease-associated isoform of human SAA, SAA1.1, is expressed as a precursor protein with an N-terminal signal peptide composed of 18 residues. The cleavage of the SP generates mature SAA1.1. To investigate whether the SP affects properties of SAA1.1, we systematically examined the structure, protein stability, and fibrillization propensity of pre-SAA1.1, which possesses the SP, and Ser-SAA1.1 without the SP but containing with an additional N-terminal serine residue. We found that the presence of the SP did not significantly affect the predominant helical structure but changed the tertiary conformation as evidenced by intrinsic fluorescence and exposed hydrophobic surfaces. Pre-SAA1.1 and Ser-SAA1.1 formed distinct oligomeric assemblies in which pre-SAA1.1 populated as tetramer and octamer, whereas Ser-SAA1.1 existed as a predominant hexamer. Pre-SAA1.1 was found significantly more stable than Ser-SAA1.1 upon thermal and chemical unfolding. Ser-SAA1.1, but not pre-SAA1.1, is capable of forming amyloid fibrils in protein misfolding study, indicating a protective role of the SP. Altogether, our results demonstrated a novel role of the SP in SAA folding and misfolding and provided a novel direction for therapeutic development of AA amyloidosis.

Current Understanding of Systemic Amyloidosis and Underlying Disease Mechanisms

Amyloidosis is a group of diverse disorders caused by misfolded proteins that aggregate into insoluble fibrils and ultimately cause organ damage. In medical practice, amyloidosis classification is based on the amyloid precursor protein type, of which amyloid immunoglobulin light chain, amyloid transthyretin, amyloid leukocyte chemotactic factor 2, and amyloid derived from serum amyloid A protein are the most common. Distinct mechanisms appear to be predominantly operational in the pathogenesis of particular types of amyloidosis, including increased protein precursor synthesis, somatic or germ line mutations, and inherent instability in the precursor protein in its wild form. An increased supply of misfolded proteins and/or a decreased capacity of the protein quality control systems can result in an imbalance that leads to increased circulation of misfolded proteins. Although the detection of mature fibrils is the basis for diagnosis of amyloidosis, a growing body of evidence has implicated the prefibrillar species as proteotoxic and key contributors to the development of the disease.

Secondary Amyloidosis and Common Variable Immunodeficiency: A Rare Association

Common variable immunodeficiency (CVID) is a disease characterized by severe antibody deficiency due to impaired B cell differentiation. It represents the most common form of primary immunodeficiency in children and adults, and its clinical manifestations include recurrent infections and chronic lung disease, gastrointestinal infections, and autoimmunity. Here, we present the case of a 47-year-old female patient with a history of CVID and recurrent Campylobacter jejuni bacteremia. She was undergoing biweekly administration of intravenous immunoglobulin for over 15 years. During hospitalization rapidly progressive oliguric renal failure was observed in association with anasarca and nephrotic syndrome. Bilateral nephromegaly was noted on an abdominal pelvic computed tomography scan. Renal biopsy was consistent with amyloidosis, and serum amyloid A protein was elevated. The diagnosis of AA amyloidosis secondary to CVID was made. The patient was started on hemodialysis and weekly intravenous immunoglobulin administration with favorable clinical outcomes.

Renal amyloidosis: a new time for a complete diagnosis

Amyloidoses are a group of disorders in which soluble proteins aggregate and deposit extracellularly in tissues as insoluble fibrils, causing organ dysfunction. Clinical management depends on the subtype of the protein deposited and the affected organs. Systemic amyloidosis may stem from anomalous proteins, such as immunoglobulin light chains or serum amyloid proteins in chronic inflammation or may arise from hereditary disorders. Hereditary amyloidosis consists of a group of rare conditions that do not respond to chemotherapy, hence the identification of the amyloid subtype is essential for diagnosis, prognosis, and treatment. The kidney is the organ most frequently involved in systemic amyloidosis. Renal amyloidosis is characterized by acellular pathologic Congo red-positive deposition of amyloid fibrils in glomeruli, vessels, and/or interstitium. This disease manifests with heavy proteinuria, nephrotic syndrome, and progression to end-stage kidney failure. In some situations, it is not possible to identify the amyloid subtype using immunodetection methods, so the diagnosis remains indeterminate. In cases where hereditary amyloidosis is suspected or cannot be excluded, genetic testing should be considered. Of note, laser microdissection/mass spectrometry is currently the gold standard for accurate diagnosis of amyloidosis, especially in inconclusive cases. This article reviews the clinical manifestations and the current diagnostic landscape of renal amyloidosis.

Presentation of Sjogren Syndrome as Nodular Pulmonary Amyloidosis

Sjogren syndrome is an autoimmune disorder that leads to dryness in the eyes and mouth. Nodular pulmonary amyloidosis is a localized amyloid deposition pathology commonly seen with monoclonal lymphoproliferative disorders. We present a patient who came in with dyspnea and was found to have nodular pulmonary amyloidosis on biopsy. Commonly associated lymphoproliferative pathologies were ruled out and on further workup, the patient was found to have Sjogren syndrome. This case demonstrates pulmonary nodular amyloidosis as a rare presentation of Sjogren syndrome in the setting of relatively well-controlled symptoms. Detection of pulmonary nodular amyloidosis should prompt evaluation of associated conditions such as malignancy and autoimmune disorders to guide further management.

Revisiting misfolding propensity of serum amyloid A1: Special focus on the signal peptide region

AA amyloidosis is the result of overproduction and aberrant processing of acute-phase serum amyloid A1 (SAA1) by hepatocytes. Proteolytic cleavage of SAA1 is believed to play a central role in AA amyloid formation. The SAA1 protein undergoes a cleavage of 18 residues consisting of the signal peptide at the N-terminal region. To better understand the mechanism behind systemic amyloidosis in the SAA1 protein, we studied the misfolding propensity of the signal peptide region. We first examined the signal peptide amino acid SAA derived from different animal species. A library of 16 peptides was designed to evaluate the propensity of aggregation. The amyloidogenic potential of each SAA1 signal peptide homolog was assessed using in silico Tango program, thioflavin T (ThT) fluorescence, transmission electron microscopy (TEM), and seeding with misfolded human SAA1 signal peptide. After 7 days of incubation, most of the SAA1 signal peptide fragments had the propensity to form fibrils at a concentration of 100 μM in 50 mM Tris buffer at 37 °C by TEM. All peptides were able to generate fibrils at a higher concentration, i.e 500 μM in 25 mM Tris buffer with 50% HFIP, by ThT. All SAA1 signal synthetic peptides designed from the different animal species had the propensity to misfold and form fibrils, particularly in species with low occurrence of systemic amyloidosis. The human SAA1 signal peptide region was capable to seed the SAA1 1–25 and 32–47 peptide regions. Characterizing fibrillar conformations are relevant for seeding intact and/or fragmented SAA, which may contribute, to the mechanism of protein misfolding. This research signifies the importance of the signal peptide region and its possible contribution to the misfolding of aggregation-prone proteins.

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Serum amyloid A1 (SAA1) signal peptide synthetic fragments have the propensity to form fibrils.

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SAA1 signal peptide, 1–25, and 51–75 regions are prone-to-aggregate.

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Human SAA1 signal peptide is capable to seeds human SAA1 1–25 and 32–47 fragments.

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SAA1 signal peptide fibrils may have a role in seeding intact and/or fragmented SAA1.

Amyloid deposition in granuloma of tuberculosis patients: A single-center pilot study

The formation of granuloma is one of the characteristic features of tuberculosis. Besides, elevated serum amyloid A (SAA) protein level is the indicator for chronic inflammation associated with tuberculosis. The linkage between tuberculosis and SAA-driven secondary amyloidosis is well documented. However, SAA-derived amyloid onset and deposition start sites are not well understood in tuberculosis. We hypothesized that granuloma could be a potential site for amyloid deposition because of the presence of SAA protein and proteases, cleaving SAA into aggregation-prone fragments. 150 tuberculosis patients were identified and biopsies were collected from the affected organs. Patients showing eosinophilic hyaline-rich deposits within granuloma and its periphery were further screened for the presence of amyloid deposits. Upon Congo red staining, these hyaline deposits exhibited characteristic apple-green birefringence under polarized light, confirming their amyloid nature in 20 patients. Further upon Immuno-histochemical staining with anti-SAA antibody, the amyloid enriched areas showed positive immunoreactivity. In this pilot study, we have shown granuloma as a potential site for serum amyloid A derived amyloid deposition in tuberculosis patients. This study would expand the clinical and fundamental research for understanding the mechanism of amyloid formation in granuloma underlying tuberculosis and other chronic inflammatory conditions.

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.

Hepatic Amyloidosis as a Rare Cause of Liver Failure: A Case Report

Amyloidosis is a systemic disease that results from the extracellular deposition of an abnormal protein called amyloid. The kidney and the heart are the most common organ affected by amyloidosis while in some cases liver involvement can be seen. Our patient is a 60-year-old African American male who presented to the emergency department because of multiple episodes of syncope over the past day. Chest x-ray and ultrasound chest were suggestive of pleural effusion for which thoracentesis was done. His hospital course was complicated with renal and liver failure. Computed tomography (CT) abdomen and pelvis was done which showed mild hepatomegaly. Liver biopsy was done which showed congo red stain positive for amyloid. The patient's clinical condition continued to worsen and he was started on hemodialysis. During hospital course, the patient developed liver failure. His family members opted for palliative care and the patient passed away during the same admission. Physicians need to be aware of the detrimental course and poor prognosis associated with hepatic and renal amyloidosis. High clinical suspicion is needed to make an early diagnosis and initiate prompt treatment. Although clinical, laboratory and radiological findings can help in suggesting amyloidosis, a tissue biopsy is needed to confirm the diagnosis of amyloidosis.

AA Amyloidosis associated with cancers

Systemic AA amyloidosis is associated with systemic inflammatory processes such as autoimmune disorders or chronic infections. In addition, AA amyloidosis can develop in a localized or systemic form in patients with malignant neoplastic disorders, and usually involves kidneys impacting renal function. Among solid tumors, renal cell carcinoma (RCC) appears to be responsible for one-quarter to half of all cancers associated with amyloidosis. Among other solid cancers, various clinical presentation and pathological types of lung cancer and basal cell carcinoma skin were reported with AA amyloidosis more often than isolated case reports on other cancers with AA amyloidosis. Symptoms from kidney involvement rather than from the tumor per se were the presenting manifestations in cases of RCC associated with AA amyloidosis. Among hematological malignancies, clonal B cell/plasma cell dyscrasias such as monoclonal gammopathy and lymphoma were noted to be associated with AA amyloidosis. In addition, AA amyloidosis was reported in a substantial number of cases treated with immune checkpoint inhibitors such as pembrolizumab and nivolumab. The mechanism of association of cancer and AA amyloidosis seems to be mediated by the immune response exacerbated from the tumor and its microenvironment or immune therapy. The mainstay of treatment consists of therapy directed against the underlying malignancy or careful withdrawal of the offending agent. This review will discuss this rare but highly morbid clinical condition.

Hidradenitis supparativa complicated by penoscrotal lymphedema and renal amyloidosis

Genital lymphedema usually develops after 4-30 years of chronic hidradenitis suppurativa (HS). However, our patient exhibited signs of it as early as 2 years after being diagnosed with HS. Renal amyloidosis is a rarely reported complication of HS. Unfortunately, our patient was asymptomatic but was found to have end-stage renal disease secondary to advanced renal amyloidosis. We report a case of a 42-year-old Indian gentleman who had HS for 9 years presenting with 2 rare complications: penoscrotal lymphedema and end-stage renal disease secondary to renal amyloidosis. The patient was treated with prednisolone and adalimumab to treat both his HS and renal amyloidosis, and was referred to general surgery to manage his genital lymphedema. We recommend following adult patients with moderate-to-severe HS and clinical duration of greater than 3 years and screening for amyloidosis before they reach end-stage organ disease, similar to what happened to our patient with end-stage renal disease.

IL-17A Is the Critical Cytokine for Liver and Spleen Amyloidosis in Inflammatory Skin Disease

Systemic amyloidosis is recognized as a serious complication of rheumatoid arthritis or inflammatory bowel disease, but also of inflammatory skin disease. However, the detailed molecular mechanism of amyloidosis associated with cutaneous inflammation remains unclear, and therapeutic approaches are limited. Here, we investigated the pathophysiology of amyloidosis secondary to cutaneous inflammation and the therapeutic effects of Janus kinase (JAK) inhibitors by examining a mouse model of spontaneous dermatitis (KCASP1Tg mice). Moreover, KCASP1Tg mice were crossed with interleukin-17A (IL-17A) knockout mice to generate IL-17A-/KCASP1Tg and examine the role of IL-17A in amyloidosis under cutaneous inflammation. KCASP1Tg mice showed severe amyloid deposition in the liver and spleen. Increased serum-neutral fat levels and decreased lymphocyte production were observed in the spleen. Overproduction of amyloidosis was partially ameliorated by the administration of JAK inhibitors and was further improved in IL-17A-/KCASP1Tg mice. IL-17A-producing cells included CD4, gamma delta, and CD8 T cells. In summary, our results from the analysis of a mouse model of dermatitis revealed that skin-derived inflammatory cytokines can induce amyloid deposition in the liver and spleen, and that the administration of JAK inhibitors and, even more, IL-17A ablation, reduced amyloidosis. This study demonstrates that active control of skin inflammation is essential to prevent internal organ amyloidosis.

The Relevance of Skin Biopsies in General Internal Medicine: Facts and Myths

Introduction

Non-dermatology medical specialties may refer patients for skin biopsies, searching for a particular diagnosis. However, the diagnostic impact of the skin biopsy is not clearly established. This article aims to assess the indications for, and evaluate the clinical relevance of, skin biopsies in non-dermatology medical specialties.

Methods

A questionnaire was sent to 23 non-dermatology specialty departments in a university medical center, requesting a list of indications for skin biopsies, as well as to 10 staff dermatologists to collect the indications of skin biopsies requested by non-dermatology specialties. Once the indications were collected, a literature search was performed to evaluate their clinical value and relevance.

Results

Eleven non-dermatology specialties provided a list of skin biopsy indications, to which staff dermatologists added seven more indications. A literature search revealed evidence-based medicine data for six diseases, that is, amyloidosis, peripheral autonomic neuropathy, Sneddon’s syndrome, intravascular lymphoma, sarcoidosis, and chronic graft-versus-host disease. Results were questionable concerning infectious endocarditis, acute graft-versus-host-disease, and the lupus band test. Skin biopsy were not evidenced as useful for the diagnosis of calciphylaxis, systemic scleroderma, Behçet’s disease, or hypermobile Ehlers–Danlos syndrome. For the diagnosis of Alport’s syndrome, pseudoxanthoma elasticum, and vascular Ehlers–Danlos syndrome, skin biopsy is currently outperformed by genetic analyses. For diagnoses such as Henoch–Schönlein purpura and Sjögren’s syndrome, skin biopsy represents an additional item among other diagnostic criteria.

Conclusion

The usefulness of skin biopsy as requested by non-dermatology specialties is only evidenced for amyloidosis, peripheral autonomic neuropathy, Sneddon’s syndrome, intravascular lymphoma, sarcoidosis, chronic graft-versus-host-disease, Henoch–Schönlein purpura, and Sjögren’s syndrome.

Interconversion between Serum Amyloid A Native and Fibril Conformations

Overexpression of serum amyloid A (SAA) can lead to a form of amyloidosis where the fibrils are made of SAA fragments, most often SAA1-76. Using Replica Exchange with Tunneling, we study the conversion of a SAA1-76 chain between the folded conformation and a fibril conformation. We find that the basins in the free energy landscape corresponding to the two motifs are separated by barriers of only about 2-3 k B T. Crucial for the assembly into the fibril structure is the salt bridge 26E-34K that provides a scaffold for forming the fibril conformation.

Left Ventricular Hypertrophy: Etiology-Based Therapeutic Options

Determining the etiologies of left ventricular hypertrophy (LVH) can be challenging due to the similarities of the different manifestations in clinical presentation and morphological features. Depending on the underlying cause, not only left ventricular mass but also left ventricular cavity size, or both, may increase. Patients with LVH remain asymptomatic for a few years, but disease progression will lead to the development of systolic or diastolic dysfunction and end-stage heart failure. As hypertrophied cardiac muscle disrupts normal conduction, LVH predisposes to arrhythmias. Distinguishing individuals with treatable causes of LVH is important for prevention of cardiovascular events and mortality. Athletic’s heart with physiological LVH does not require treatment. Frequent causes of hypertrophy include etiologies due to pressure/volume overload, such as systemic hypertension, hypertrophic cardiomyopathy, or infiltrative cardiac processes such as amyloidosis, Fabry disease, and sarcoidosis. Hypertension and aortic valve stenosis are the most common causes of LVH. Management of LVH involves lifestyle changes, medications, surgery, and implantable devices. In this review we systematically summarize treatments for the different patterns of cardiac hypertrophy and their impacts on outcomes while informing clinicians on advances in the treatment of LVH due to Fabry disease, cardiac amyloidosis, and hypertrophic cardiomyopathy.

AL Lambda Amyloidosis Activates Acute Liver Failure in the Absence of Plasma Cell Dyscrasia

A patient with systemic amyloidosis developed portal hypertension, acute liver failure and multiorgan dysfunction. Extensive testing was unrevealing for paraproteinemia, plasma cell dyscrasia, infectious, or inflammatory conditions. He was transferred to our institution for orthotopic liver transplant evaluation but was ultimately declined given clinical instability and dysautonomia. Post-mortem evaluation revealed extensive amyloid deposition in multiple organs determined to be AL-lambda amyloidosis.

A multicenter study of the clinical, laboratory characteristics, and potential prognostic factors in patients with amyloid A amyloidosis on hemodialysis

INTRODUCTION

While light chain (AL) amyloidosis is more common in western countries, the most common type of amyloidosis is amyloid A (AA) amyloidosis in Eastern Mediterranean Region, including Turkey. Although worse prognosis has been attributed to the AL amyloidosis, AA amyloidosis can be related to higher mortality under renal replacement therapies. However, there are no sufficient data regarding etiology, clinical presentation, and prognostic factors of AA amyloidosis. The objective of our study is to evaluate the clinical, laboratory characteristics, and possible predictive factors related to mortality in patients with AA amyloidosis undergoing hemodialysis (HD).

METHODS

This multicenter, cross-sectional study was a retrospective analysis of 2100 patients on HD. It was carried out in 14 selected HD centers throughout Turkey. Thirty-two patients with biopsy-proven AA amyloidosis and thirty-two control patients without AA amyloidosis undergoing HD were included between October 2018 and October 2019. There was no significant difference between the groups in terms of age and dialysis vintage. Causes of AA amyloidosis, treatment (colchicine and/or anti-interleukin 1 [IL] treatment), and the number of familial Mediterranean fever (FMF) attacks in the last year in case of FMF, systolic and diastolic blood pressures, biochemical values such as mean CRP, hemoglobin, serum albumin, phosphorus, calcium, PTH, ferritin, transferrin saturation, total cholesterol levels, EPO dose, erythropoietin-stimulating agents resistance index, interdialytic fluid intake, body mass indexes, heparin dosage, UF volume, and Kt/V data in the last year were collected by retrospective review of medical records.

FINDINGS

Prevalence of AA amyloidosis was found to be 1.87% in HD centers. In amyloidosis and control groups, 56% and 53% were male, mean age was 54 ± 11 and 53 ± 11 years, and mean dialysis vintage was 104 ± 94 and 107 ± 95 months, respectively. FMF was the most common cause of AA amyloidosis (59.5%). All FMF patients received colchicine and the mean colchicine dose was 0.70 ± 0.30 mg/day. 26.3% of FMF patients were unresponsive to colchicine and anti-IL-1 treatment was used in these patients. In AA amyloid and control groups, erythropoietin-stimulating agents resistance index were 7.88 ± 3.78 and 5.41 ± 3.06 IU/kg/week/g/dl, respectively (p = 0.008). Additionally, higher CRP values (18.78 ± 18.74 and 10.61 ± 10.47 mg/L, p = 0.037), lower phosphorus (4.68 ± 0.73 vs. 5.25 ± 1.04 mg/dl, p = 0.014), total cholesterol (135 ± 42 vs. 174 ± 39 mg/dl, p < 0.01), and serum albumin (3.67 ± 0.49 mg/dl, 4.03 ± 0.22, p < 0.01) were observed in patients with AA amyloidosis compared to the control group.

DISCUSSION

In this study, we found that long-term prognostic factors including higher inflammation, malnutritional parameters, and higher erythropoietin-stimulating agents resistance index were more frequent in AA amyloidosis patients under HD treatment.

Janus Kinase Inhibitors Ameliorated Gastrointestinal Amyloidosis and Hypoalbuminemia in Persistent Dermatitis Mouse Model

Malnutrition is not only regarded as a complication of rheumatoid arthritis and inflammatory bowel disease but also that of inflammatory skin disease; however, the mechanisms and efficacy of its treatment have not been elucidated. Using a mouse model of dermatitis, we investigated the pathophysiology of malnutrition in inflammatory skin conditions and efficacy of its treatment. We employed spontaneous skin inflammation mice models overexpressing human caspase-1 in the epidermal keratinocytes. Body weight, nutrition level, and α1-antitrypsin fecal concentration were measured. The gastrointestinal tract was histologically and functionally investigated. Fluorescein isothiocyanate (FITC)-dextran was forcibly fed on an empty stomach, and plasma FITC-dextran was measured. The treatment efficacy of antibodies against tumor necrosis factor-α (TNF-α) and interleukin (IL)-α/β as well as Janus kinase (JAK) inhibitors was investigated. Compared with wild-type littermates, the inflammatory skin mice models showed a lowered body weight, reduction of serum albumin level, amyloid deposition in the stomach, small intestine, and large intestine, and increased α1-antitrypsin fecal concentration. However, the plasma FITC-dextran was unchanged between the dermatitis models and wild-type littermates. The over-produced serum amyloid A1 in the liver was detected in the plasma in the dermatitis model. Antibodies against TNF-α and IL-α/β showed partial effects on amyloid deposition; however, JAK inhibitors improved gastrointestinal amyloidosis with the improvement of skin symptoms. Chronic dermatitis is closely related to secondary amyloidosis in the gastrointestinal tract, resulting in hypoalbuminemia. Therefore, active control of skin inflammation is essential for preventing gastrointestinal complications.

The role of minor salivary glands' biopsy in the diagnosis of Sjögren's syndrome and other systemic diseases

BACKGROUND

The minor salivary glands' biopsy is a minimally invasive procedure used for the diagnosis of Sjögren's syndrome. Its significance has also been reported in other inflammatory/infiltrative diseases. The objectives are to investigate its use in the diagnosis of Sjögren's syndrome, as well as to evaluate its role in the diagnosis of amyloidosis and sarcoidosis.

METHODS

A retrospective analysis was carried out on patients who underwent minor salivary glands' biopsies between April of 2014 and December of 2017.

RESULTS

A total of 173 patients were identified. Of the patients with suspected Sjögren's syndrome, in 40% of the cases there was evidence of lymphocytic sialadenitis. The antibodies against SSA, antinuclear antibodies and the Rheumatoid Factor correlated significantly with the presence of lymphocytic sialadenitis. The result of the minor salivary glands' biopsies allowed an increase of 12.4% of patients who met the criteria defined by the American - European Consensus Group. Of the patients with suspected amyloidosis (25%), the biopsies were positive in 4 patients.

CONCLUSION

The minor salivary glands' biopsy is a simple procedure with effectiveness in the diagnosis of Sjögren's syndrome and amyloidosis. In this study, its use increased the number of patients who met the Sjögren's syndrome classification criteria. It also appears to be useful in the diagnosis of amyloidosis.

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.

Trends in amyloidosis in spondyloarthritis: results from the Spanish National Inpatient Registry over a 17-year period (1999-2015)-TREND-EspA study

Objective

To assess the incidence of amyloidosis and trends therein in patients with spondyloarthritis (SpA) over a long period (17 years).

Methods

An observational retrospective population-based matched cohort study was conducted. All the admissions of patients with SpA, including ankylosing spondylitis (AS), psoriatic arthritis (PsA), arthritis associated with inflammatory bowel disease (SpA-IBD) and reactive arthritis (ReA), reported between 1999 and 2015, were analysed and a control group matched by age, sex and year of admission was selected. Incidence rates for amyloidosis were calculated. Generalised linear models were used for trend analysis and unconditional logistic regression for calculating crude and adjusted ORs (AOR) to assess the association between amyloidosis and SpA.

Results

The study database contained data on 107 140 admissions in each group. Between 1999 and 2015, 792 patients in the SpA cohort (0.7% of all admissions) had a diagnosis of amyloidosis versus 68 in the non-SpA cohort (0.1%) (p<0.001). From 1999 to 2015, incidence rates of amyloidosis tended to decrease in the SpA cohort (−4.63%/year overall), while they increased in the Non-SpA cohort (+10.25%/year overall). We found strong associations of amyloidosis with all SpAs (AOR 10.4; 95% CI 8.2 to 13.3) and with each type studied (AORs 10.05 (7.84 to 12. 88) for AS, 9.5 (7.3 to 12.4) for PsA, 22.9 (16.6 to 31.7) for SpA-IBD and 10.1 (6.1 to 16.7) for ReA).

Conclusions

Incidence of amyloidosis among patients with SpA has strongly decreased in Spain. Amyloidosis is most strongly associated with SpA-IBD while the strength of association with PsA and ReA is similar to that with AS.

Kidney-limited AL amyloidosis: a case report and review of the literature

Amyloidosis involves the deposition of abnormal proteins in various tissues and results in progressive organ dysfunction, commonly affecting multiple organs. Two types of systemic amyloidosis are AA and AL; the former is associated with acute phase reactions and the latter is composed of light chain immunoglobulins. This disease commonly affects the kidneys and is evidenced by massive proteinuria. A biopsy is the gold standard of diagnosis, with Congo Red staining revealing an apple-green birefringence under polarized light. Although the kidneys are frequently affected in this disease, it is rare that amyloidosis is limited to the kidneys without involvement of other organs. We present an 83-year-old female with bilateral lower extremity swelling for several months who was found to have 12.374 grams of protein in a 24-hour urine sample and a large amount of free lambda chains. A renal biopsy demonstrated renal amyloidosis of the AL type. Serum immunofixation and flow cytometry were unremarkable for any plasma dyscrasia; a bone marrow biopsy did not reveal systemic amyloidosis and imaging with PET/CT scan did not show evidence of other organ involvement. She was diagnosed with renal-limited amyloidosis and started on bortezomib, melphalan, and steroids. Clinicians should be aware of the signs and symptoms of amyloidosis, specifically its ability to present with unusual involvement of individual organs.

Shear wave elastography evaluation of liver, pancreas, spleen and kidneys in patients with familial mediterranean fever and amyloidosis

OBJECTIVES

Amyloid deposits in a visceral organ can contribute to tissue stiffness that could be measured with shear wave elastography (SWE). We aimed to investigate changes in organ stiffness in conjunction with laboratory parameters in patients with Familial Mediterranean Fever (FMF) and amyloidosis.

METHODS

This prospective study included 27 FMF patients, 11 patients with amyloidosis, and 38 healthy controls. Median shear wave elasticity values of the liver, spleen, both kidneys, and pancreas on SWE were compared among study and control groups. The mean values of CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate) were compared by the t-test and the median of SAA (serum amyloid A protein) was compared with the Mann-Whitney U test between FMF groups with and without amyloidosis. Spearman's correlation analysis was performed to reveal the association between stiffness values and laboratory parameters.

RESULTS

The median liver, spleen, kidney, and pancreas elasticity values were significantly higher in the FMF group with amyloidosis compared to control subjects. The median kidney stiffness values in the FMF group with or without amyloidosis were significantly higher compared to control subjects. Median liver stiffness values in FMF patients with amyloidosis were significantly higher than FMF patients without amyloidosis. There were statistically significant positive correlations between the CRP (p = 0.001, r = 0.56), ESR (p = 0.001, r = 0.61), and SAA (p = 0.002, r = 0.53) levels with spleen stiffness, and CRP (p = 0.006, r = 0.48) and ESR (p = 0.001,r = 0.61) levels with pancreas stiffness, and ESR (p = 0.004, r = 0.51) levels with the left kidney stiffness.

CONCLUSION

SWE could be a potential tool for noninvasive follow-up of FMF patients and also amyloid deposition.

ADVANCES IN KNOWLEDGE

Both acute inflammation and amyloidosis in the FMF patients could increase organ stiffness.

Immunohistochemical typing of amyloid in fixed paraffin-embedded samples by an automatic procedure: Comparison with immunofluorescence data on fresh-frozen tissue

Amyloidosis comprises a spectrum of disorders characterized by the extracellular deposition of amorphous material, originating from an abnormal serum protein. The typing of amyloid into its many variants represents a pivotal step for a correct patient management. Several methods are currently used, including mass spectrometry, immunofluorescence, immunohistochemistry, and immunogold labeling. The aim of the present study was to investigate the accuracy and reliability of immunohistochemistry by means of a recently developed amyloid antibody panel applicable on fixed paraffin-embedded tissues in an automated platform. Patients with clinically and pathologically proven amyloidosis were divided into two cohorts: a pilot one, which included selected amyloidosis cases from 2009 to 2018, and a retrospective one (comprising all consecutive amyloidosis cases analyzed between November 2018 and May 2020). The above-referred panel of antibodies for amyloid classification was tested in all cases using an automated immunohistochemistry platform. When fresh-frozen material was available, immunofluorescence was also performed. Among 130 patients, a total of 143 samples from different organs was investigated. They corresponded to 51 patients from the pilot cohort and 79 ones from the retrospective cohort. In 82 cases (63%), fresh-frozen tissue was tested by immunofluorescence, serving to define amyloid subtype only in 30 of them (36.6%). On the contrary, the automated immunohistochemistry procedure using the above-referred new antibodies allowed to establish the amyloid type in all 130 cases (100%). These included: ALλ (n = 60, 46.2%), ATTR (n = 29, 22.3%), AA (n = 19, 14.6%), ALκ (n = 18, 13.8%), ALys (n = 2, 1.5%), and Aβ₂M amyloidosis (n = 2, 1.5%). The present immunohistochemistry antibody panel represents a sensitive, reliable, fast, and low-cost method for amyloid typing. Since immunohistochemistry is available in most pathology laboratories, it may become the new gold standard for amyloidosis classification, either used alone or combined with mass spectrometry in selected cases.

The risk, predictors, and outcomes of amyloidosis in ankylosing spondylitis: a longitudinal population-based cohort study

OBJECTIVE

The risk of amyloidosis during the course of ankylosing spondylitis (AS) is yet to be firmly established. We aimed to evaluate the risk, predictors, and prognostic outcomes of amyloidosis among patients with AS.

METHODS

A population-based cohort study was conducted comparing AS patients (n = 5,911) with age-, sex- and ethnicity-matched control subjects (n = 29 007) with regard to incident cases of amyloidosis. Hazard ratios (HRs) and odds ratios (ORs) were estimated by Cox regression and logistic regression analyses, respectively.

RESULTS

The incidence rate of amyloidosis was 2.15 (95% CI, 1.09-2.82) and 0.35 (95% CI, 0.16-0.66) per 10 000 person-years among patients with AS and controls, respectively. The risk of incident amyloidosis was >6-folds higher among patients with AS relative to control subjects (adjusted HR, 6.16; 95% CI, 2.43-15.62; p< 0.001). A higher comorbidity burden (OR, 1.36; 95% CI, 1.08-1.73; p= 0.010) was found to predict an increased susceptibility to amyloidosis in AS patients. Compared with other patients with AS, those with AS and comorbid amyloidosis had a 14-fold increased risk of end-stage renal disease necessitating dialysis (adjusted HR, 14.7; 95% CI, 2.0-107.2; p= 0.008), but comparable risk of all-cause mortality (adjusted HR, 2.16; 95% CI, 0.69-6.71; p= 0.174).

CONCLUSIONS

Patients with AS are at an increased risk of amyloidosis. AS-associated amyloidosis is associated with an elevated risk of dialysis dependence. Awareness of the burden and consequences of this complication may be of help for rheumatologists managing patients with AS.