Post-translational modification of amyloid a protein in patients with AA amyloidosis

Amyloid ◽  
2021 ◽  
pp. 1-8
Author(s):  
Barbara Kluve-Beckerman ◽  
Justin T. Smith ◽  
Carlie Ivancic ◽  
Merrill D. Benson
Keyword(s):  
Post Translational Modification ◽  
Aa Amyloidosis ◽  
Amyloid A

scholarly journals Aggregation of Mouse Serum Amyloid A Protein Was Promoted by Amyloid-Enhancing Factors with the More Genetically Homologous Serum Amyloid A

2021 ◽  
Vol 22 (3) ◽  
pp. 1036
Author(s):  
Xuguang Lin ◽  
Kenichi Watanabe ◽  
Masahiro Kuragano ◽  
Kiyotaka Tokuraku
Keyword(s):  
Amino Acid ◽  
Serum Amyloid A ◽  
Animal Species ◽  
Amino Acid Sequences ◽  
Serum Amyloid ◽  
Mouse Serum ◽  
Aa Amyloidosis ◽  
Basic Residue ◽  
Amyloid A ◽  
Serum Amyloid A Protein

Amyloid A (AA) amyloidosis is a condition in which amyloid fibrils characterized by a linear morphology and a cross-β structure accumulate and are deposited extracellularly in organs, resulting in chronic inflammatory diseases and infections. The incidence of AA amyloidosis is high in humans and several animal species. Serum amyloid A (SAA) is one of the most important precursor amyloid proteins and plays a vital step in AA amyloidosis. Amyloid enhancing factor (AEF) serves as a seed for fibril formation and shortens the onset of AA amyloidosis sharply. In this study, we examined whether AEFs extracted and purified from five animal species (camel, cat, cattle, goat, and mouse) could promote mouse SAA (mSAA) protein aggregation in vitro using quantum-dot (QD) nanoprobes to visualize the aggregation. The results showed that AEFs shortened and promoted mSAA aggregation. In addition, mouse and cat AEFs showed higher mSAA aggregation-promoting activity than the camel, cattle, and goat AEFs. Interestingly, homology analysis of SAA in these five animal species revealed a more similar amino acid sequence homology between mouse and cat than between other animal species. Furthermore, a detailed comparison of amino acid sequences suggested that it was important to mSAA aggregation-promoting activity that the 48th amino acid was a basic residue (Lys) and the 125th amino acid was an acidic residue (Asp or Glu). These data imply that AA amyloidosis exhibits higher transmission activity among animals carrying genetically homologous SAA gene, and may provide a new understanding of the pathogenesis of amyloidosis.

scholarly journals Serum amyloid A forms stable oligomers that disrupt vesicles at lysosomal pH and contribute to the pathogenesis of reactive amyloidosis

2017 ◽  
Vol 114 (32) ◽  
pp. E6507-E6515 ◽  
Author(s):  
Shobini Jayaraman ◽  
Donald L. Gantz ◽  
Christian Haupt ◽  
Olga Gursky
Keyword(s):  
Serum Amyloid A ◽  
Major Complication ◽  
Lipid Vesicles ◽  
Serum Amyloid ◽  
High Density Lipoproteins ◽  
Aa Amyloidosis ◽  
Intrinsically Disordered ◽  
Amyloid A ◽  
Α Helix ◽  
Structural Methods

Serum amyloid A (SAA) is an acute-phase plasma protein that functions in innate immunity and lipid homeostasis. SAA is a protein precursor of reactive AA amyloidosis, the major complication of chronic inflammation and one of the most common human systemic amyloid diseases worldwide. Most circulating SAA is protected from proteolysis and misfolding by binding to plasma high-density lipoproteins. However, unbound soluble SAA is intrinsically disordered and is either rapidly degraded or forms amyloid in a lysosome-initiated process. Although acidic pH promotes amyloid fibril formation by this and many other proteins, the molecular underpinnings are unclear. We used an array of spectroscopic, biochemical, and structural methods to uncover that at pH 3.5–4.5, murine SAA1 forms stable soluble oligomers that are maximally folded at pH 4.3 with ∼35% α-helix and are unusually resistant to proteolysis. In solution, these oligomers neither readily convert into mature fibrils nor bind lipid surfaces via their amphipathic α-helices in a manner typical of apolipoproteins. Rather, these oligomers undergo an α-helix to β-sheet conversion catalyzed by lipid vesicles and disrupt these vesicles, suggesting a membranolytic potential. Our results provide an explanation for the lysosomal origin of AA amyloidosis. They suggest that high structural stability and resistance to proteolysis of SAA oligomers at pH 3.5–4.5 help them escape lysosomal degradation, promote SAA accumulation in lysosomes, and ultimately damage cellular membranes and liberate intracellular amyloid. We posit that these soluble prefibrillar oligomers provide a missing link in our understanding of the development of AA amyloidosis.

scholarly journals Rituximab Therapy in Renal Amyloidosis Secondary to Rheumatoid Arthritis

Biomolecules ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 136 ◽  
Author(s):  
Levent Kilic ◽  
Abdulsamet Erden ◽  
Yusuf Sener ◽  
Berkan Armagan ◽  
Alper Sari ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Clinical Improvement ◽  
Inflammatory Diseases ◽  
Case Series ◽  
New Drugs ◽  
Renal Amyloidosis ◽  
Secondary Amyloidosis ◽  
Aa Amyloidosis ◽  
Amyloid A ◽  
Significant Clinical Improvement

Secondary amyloid A (AA) amyloidosis is a late and serious complication of poorly controlled, chronic inflammatory diseases. Rheumatoid arthritis (RA) patients with poorly controlled, longstanding disease and those with extra-articular manifestations are under risk for the development of AA amyloidosis. Although new drugs have proven to be significantly effective in the treatment of secondary AA amyloidosis, no treatment modality has proven to be ideal. To date, only in small case series preliminary clinical improvement have been shown with rituximab therapy for AA amyloidosis secondary to RA that is refractory to TNF-α inhibitors (TNF-i) therapy. In these case series, we assessed the efficacy and safety of rituximab therapy for patients with RA and secondary amyloidosis. Hacettepe University Biologic Registry was developed at 2005. The data of the RA patients who were prescribed a biological drug were recorded regularly. Patients with biopsy proven AA amyloidosis patients were screened. Of 1022 RA patients under biologic therapy, 0.7% patients had clinically apparent histologically confirmed amyloidosis. Four of seven patients who were prescribed rituximab at least one infusion enrolled to those case series. Two of four patients showed significant clinical improvement and one of them also had decrease in proteinuria and the other one had stable renal function and proteinuria. The main goal for the treatment of AA amyloidosis is to control the activity of the underlying disorder. In this study, we showed that rituximab may be an effective treatment in RA patients with amyloidosis who were unresponsive to conventional disease modifying anti-rheumatic drugs (DMARDs) and/or TNFi.

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

2016 ◽  
Vol 54 (1) ◽  
pp. 99-110 ◽  
Author(s):  
K. Watanabe ◽  
K. Uchida ◽  
J. K. Chambers ◽  
N. Ushio ◽  
H. Nakayama
Keyword(s):  
Receptor Antagonist ◽  
Knockout Mice ◽  
Interleukin 1 ◽  
Recovery Process ◽  
Amyloid Deposition ◽  
Aa Amyloidosis ◽  
Amyloid A ◽  
Enhancing Factor ◽  
Amyloid Deposits ◽  
Amyloid Enhancing Factor

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.

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

2021 ◽  
Vol 8 ◽  
Author(s):  
Per Eriksson ◽  
Johan Mölne ◽  
Lina Wirestam ◽  
Christopher Sjöwall
Keyword(s):  
Ankylosing Spondylitis ◽  
Therapeutic Option ◽  
Relevant Literature ◽  
Acute Phase Reactant ◽  
Renal Amyloidosis ◽  
Secondary Amyloidosis ◽  
Aa Amyloidosis ◽  
Beneficial Effects ◽  
Amyloid A ◽  
Inflammatory Conditions

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.

An Ancillary Tool for the Diagnosis of Amyloid A Amyloidosis in a Variety of Domestic and Wild Animals

2005 ◽  
Vol 42 (2) ◽  
pp. 132-139 ◽  
Author(s):  
S. Shtrasburg ◽  
R. Gal ◽  
E. Gruys ◽  
S. Perl ◽  
B. M. Martin ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Polyacrylamide Gel Electrophoresis ◽  
Amyloid Deposit ◽  
Wild Animals ◽  
Aa Amyloidosis ◽  
Tissue Samples ◽  
Amyloid A ◽  
Congo Red Staining ◽  
Species Specific

Immunohistochemistry, the standard method for diagnosing amyloid A (AA) amyloidosis, is limited in animals because it requires a large array of animal-specific anti-AA antibodies, not commercially available. The Shtrasburg method (SH method) is a highly specific and sensitive technique, helping in the diagnosis and determination of AA amyloidosis in humans. The aim of this study is to determine whether the SH method is applicable in the diagnosis of AA amyloidosis in a variety of animals. Tissue samples were obtained from animals suffering from spontaneous or experimentally induced AA amyloidosis (mice, hamsters, guinea pigs, cheetahs, cats, cows, ducks, a dog, a goose, a chicken, and a turaco). Detection of the amyloid and quantitative evaluation were performed using Congo red staining, and specific AA typing was performed by the potassium permanganate technique. The studied tissues were subjected to the SH method, which confirmed the AA nature of the amyloid deposit, by displaying in polyacrylamide gel electrophoresis protein bands consistent with the molecular weight of the species-specific AA, in all the animals examined, except mice, hamsters, and guinea pigs. N-terminal analysis of these bands corroborated their AA origin. We conclude that the SH method may be used as an ancillary simple tool for the diagnosis of AA amyloidosis in a large number of domestic and wild animals. Moreover, our findings further increase the feasibility of applying this method in humans.

scholarly journals Allelic Diversity in the Serum Amyloid A2 Gene and Amyloid A Amyloidosis in a Breeding Colony of Zebra Finches (Taeniopygia guttata)

2019 ◽  
Vol 69 (5) ◽  
pp. 425-431 ◽  
Author(s):  
Lisa J Shientag ◽  
Oscar A Cabrera ◽  
Gregory J Pazour
Keyword(s):  
Amino Acid ◽  
Allelic Diversity ◽  
Taeniopygia Guttata ◽  
Amino Acid Substitutions ◽  
Zebra Finches ◽  
Comorbid Conditions ◽  
Aa Amyloidosis ◽  
Breeding Colony ◽  
Amyloid A ◽  
High Incidence

A high incidence of amyloid A (AA) amyloidosis was observed in the research breeding colony of zebra finches at our institution. Some birds with hepatic AA amyloidosis were asymptomatic for comorbid conditions frequently associated with the development of AA amyloidosis, whereas other birds with comorbid conditions failed to develop AA amyloidosis, suggesting a potential genetic component to the disease. Sequencing the SAA2 gene from 20 birds yielded 18 distinct sequences that coded for 5 isoforms of the protein. Most of the amino acid substitutions are unlikely to affect the protein's structure or function, but 2 changes—R52L and V84M—were predicted to be disruptive. In particular, R52 is highly conserved across vertebrates, with only arginine or lysine found at this position in reported sequences to date. The atypical R52L substitution occurred in 2 otherwise healthy birds with hepatic AA amyloidosis, supporting the idea that this change is pathogenic.

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