The amyloidosis of juvenile rheumatoid arthritis--comparative studies in Polish and American children. I. Levels of serum SAA protein

Serum Amyloid A in Inflammatory Rheumatic Diseases: A Compendious Review of a Renowned Biomarker

Serum amyloid A (SAA) is an acute phase protein with a significant importance for patients with inflammatory rheumatic diseases (IRD). The central role of SAA in pathogenesis of IRD has been confirmed by recent discoveries, including its involvement in the activation of the inflammasome cascade and recruitment of interleukin 17 producing T helper cells. Clinical utility of SAA in IRD was originally evaluated nearly half a century ago. From the first findings, it was clear that SAA could be used for evaluating disease severity and monitoring disease activity in patients with rheumatoid arthritis and secondary amyloidosis. However, cost-effective and more easily applicable markers, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), overwhelmed its use in clinical practice. In the light of emerging evidences, SAA has been discerned as a more sensitive biomarker in a wide spectrum of IRD, especially in case of subclinical inflammation. Furthermore, a growing number of studies are confirming the advantages of SAA over many other biomarkers in predicting and monitoring response to biological immunotherapy in IRD patients. Arising scientific discoveries regarding the role of SAA, as well as delineating SAA and its isoforms as the most sensitive biomarkers in various IRD by recently developing proteomic techniques are encouraging the revival of its clinical use. Finally, the most recent findings have shown that SAA is a biomarker of severe Coronavirus disease 2019 (COVID-19). The aim of this review is to discuss the SAA-involving immune system network with emphasis on mechanisms relevant for IRD, as well as usefulness of SAA as a biomarker in various IRD. Therefore, over a hundred original papers were collected through an extensive PubMed and Scopus databases search. These recently arising insights will hopefully lead to a better management of IRD patients and might even inspire the development of new therapeutic strategies with SAA as a target.

AA amyloidosis secondary to adult onset Still's disease: About 19 cases

OBJECTIVE

Adult onset Still's disease (AOSD) is an inflammatory disorder characterized by high spiking fever, evanescent rash, polyarthritis, and many other systemic manifestations. Recurrent or persistent disease can lead to AA amyloidosis (AAA). Our objectives were to present 3 French cases and perform a systematic review of the literature, in order to determine the prevalence, characteristics, predisposing factors, and therapeutic response of AOSD-related AAA.

METHODS

A systematic literature review was performed by searching MEDLINE from 1971 to 2018. Two independent investigators selected reports of AAA complicating AOSD. New French cases were identified with the help of the Reference Center for rare Auto-Inflammatory Diseases and Amyloidosis (CEREMAIA). Patients with juvenile idiopathic arthritis were excluded.

RESULTS

The prevalence of AAA in AOSD was 0.88% (95%CI [0.49-1.28]) based on 45 articles. In addition to 3 new cases from the CEREMAIA, 16 patients were assessed for clinical presentation, risk factors, and therapeutic response of AOSD-related AAA. Mean age at AOSD onset was 29.6 ± 12.6 years, with a mean delay before AAA diagnosis of 16.75±5.8 years. Renal involvement was the most common manifestation of AAA. The majority of patients presented active AOSD at AAA diagnosis. Various treatments of AOSD-related AAA were attempted including corticosteroids and biotherapies.

CONCLUSION

AAA is a rare and severe complication that may occur during the course of uncontrolled active AOSD. It could be prevented by early diagnosis and better control of AOSD, with more frequent use of biotherapies.

Pathophysiology and treatment of systemic amyloidosis

Amyloid is an abnormal extracellular fibrillar protein deposit in the tissues. In humans, more than 25 different proteins can adopt a fibrillar conformation in vivo that results in the pathognomonic tinctorial property of amyloid (that is, green birefringence when an affected tissue specimen is stained with Congo red dye and viewed by microscopy under cross-polarized light). Amyloid deposition is associated with disturbance of organ function and causes a wide variety of clinical syndromes that are classified according to the respective fibril protein precursor. Systemic amyloidosis, in which amyloid deposits are widespread and typically accumulate gradually, continues to be fatal and is responsible for about one in 1,500 deaths per year in the UK. Advances in our understanding of the pathogenesis of systemic amyloidosis have resulted in the identification of new therapeutic targets, and several drugs with novel mechanisms of action are currently under development. Meanwhile, an increased awareness of amyloidosis coupled with enhancements to existing diagnostic techniques and therapeutic strategies have already resulted in better outcomes for patients with the disease.

Systemic AA amyloidosis

Systemic AA amyloidosis is a rare complication of chronic inflammatory disorders. The amyloid fibrils are derived from serum amyloid A protein, an acute phase protein synthesized in the liver. Clinical presentation is most commonly due to the consequences of renal involvement, with proteinuria and progressive renal decline. Progression to end stage renal failure is common. Management is currently centred on reducing the supply of the precursor protein by treating the underlying inflammatory condition, whilst supporting the affected organs. Monitoring of the serum amyloid A protein is vital to assess whether there is adequate suppression of the underlying disease. The level of serum amyloid A protein is a powerful predictor of both patient survival and renal outcome. In patients with adequate suppression of the serum amyloid A protein amyloid deposits can be seen to regress and renal function can be stabilised and even improve.

A marked decline in the incidence of renal replacement therapy for amyloidosis associated with inflammatory rheumatic diseases - data from nationwide registries in Finland

Risk for amyloidosis in rheumatic diseases is associated with a long-lasting inflammation. To assess possible changes in the incidence of terminal uraemia due to amyloidosis associated with rheumatic diseases on a nationwide basis, we scrutinised the files of the Finnish Registry for Kidney Diseases for patients suffering from amyloidosis associated with rheumatoid arthritis (RA), ankylosing spondylitis (AS) or juvenile idiopathic arthritis (JIA) over the period 1995-2008. The registry has an estimated 97-99% coverage of all patients accepted for renal replacement therapy (RRT) in the country. Data on the consumption of antirheumatic drugs were collected from two sources: the Social Insurance Institution's Drug Reimbursement Register, and the Sales Register of the National Agency for Medicines from the above period. Altogether 264 cases were identified. Two hundred twenty-nine of them had RA, 15 AS and 20 JIA. When the total annual number of new admissions to RRT varied between 20 and 37 at the end of 1990s, it was under half of that from 2002 onwards. Over this period, the number of users of low-dose methotrexate (MTX) has increased 3.6-fold, the drug being the most frequently used disease modifying anti-rheumatic drug in Finland. The present nationwide series is the first to show that the incidence of end-stage renal disease due to amyloidosis associated with rheumatic diseases is decreasing. An obvious reason for this is intensive anti-rheumatic drug therapy.

More evidence of declining incidence of amyloidosis associated with inflammatory rheumatic diseases

OBJECTIVE

To assess the incidence, prevalence, and outcome of amyloidosis associated with inflammatory rheumatic diseases.

METHODS

An observational study was performed in the outpatient department of Kainuu Central Hospital from 1993 to 2007. The following criteria were used for the performance of abdominal subcutaneous fat aspiration (ASFA) and/or rectal biopsies: erythrocyte sedimentation rate (ESR) > 40 mm/h at two consecutive visits; and proteinuria (> 0.5 g/day) or serum creatinine > 150 μmol/L. Renal biopsy was performed when there was a high suspicion of amyloidosis in cases with negative findings in the above-mentioned biopsies. In addition, amyloid staining was used routinely for mucosal specimens taken in gastroscopy and colonoscopy. The patients were followed until death or to the end of 2007.

RESULTS

New diagnoses of amyloidosis in the consecutive 5-year periods from 1993 onwards numbered 11, 3, and 5, respectively. During the study period, there was a mean annual incidence of amyloidosis of 1.8 [95% confidence interval (CI) 1.1-2.8)/100,000]. At the end of 2007 there were eight subjects with amyloidosis, giving a point prevalence of 12.0/100,000 (95% CI 5.2-23.6). Five patients out of the 19 underwent haemodialysis because of terminal uraemia and three of them also had renal transplantation. Overall, 12 (63%) patients died after a median survival time of 6 (95% CI 4-8) years, one-third from amyloidosis. The 5-year survival rate of the series was 67% (95% CI 41-86).

CONCLUSION

Amyloidosis is rarely encountered today. ASFA or rectal biopsy facilitates its early diagnosis.

Serum amyloid P component scintigraphy and turnover studies for diagnosis and quantitative monitoring of AA amyloidosis in juvenile rheumatoid arthritis

OBJECTIVE

To evaluate aspects of the natural history of AA amyloidosis complicating juvenile rheumatoid arthritis (JRA), and its response to therapy with chlorambucil.

METHODS

Scintigraphy and 7-day turnover studies were performed in JRA patients with histologically proven (n = 35) or clinically suspected (n = 30) AA amyloidosis, following intravenous injection of 123I and 125I-labeled serum amyloid P component (SAP). Prospective monitoring studies were performed over 2-3 years in 20 patients with amyloidosis. All but 2 amyloidosis patients were treated with chlorambucil.

RESULTS

Positive scanning results were obtained in all patients in whom imaging was performed within 12 years of positive biopsy findings of amyloid and in 5 patients with clinically suspected amyloidosis. Negative scanning results with normal SAP metabolism, indicating regression of amyloid, were obtained in 4 patients whose amyloidosis had been in full clinical remission for more than 12 years. Prospective monitoring studies in patients whose JRA-associated inflammatory activity was in remission demonstrated regression of amyloid in 8 patients and no substantial changes in 8 others; however, in 4 further patients with active inflammation, there was accumulation of amyloid. There was a very poor correlation between the amount of amyloid present at a particular site and the resultant organ dysfunction.

CONCLUSION

Radiolabeled SAP scintigraphy and turnover studies are useful complementary tools in the diagnosis, screening, and quantitative monitoring of type AA amyloidosis in JRA. The amyloid deposits may progress and/or regress at different rates in different anatomic sites over short periods.

Amyloidosis

Amyloidosis is a heterogenous group of diseases characterized by deposition of a fibrillar, proteinaceous material, amyloid, in various tissues and organs. Increasing knowledge about the different proteins that constitute the amyloid fibrils has made it possible to classify amyloidosis by the fibril protein, which appears more rational than the traditional classification by its clinical expression. A serum protein is the precursor of the amyloid fibril protein in the various systemic forms of amyloidosis. Although the chemical composition of amyloid is presently well known, the pathogenetic processes that convert such proteins into a fibrillar form and lay them down in the tissues are far from clarified. This review describes the amyloid deposits, some putative pathogenetic mechanisms, and the clinical, therapeutic, and prognostic aspects of the most important forms of amyloid disease.

Alterations in lipoprotein density classes in infantile visceral leishmaniasis: presence of apolipoprotein SAA

This study describes the alterations in the plasma lipoproteins from nine young Tunisian children with active visceral Leishmaniasis. The plasma lipid profile from affected patients was characterized by a marked hypertriglyceridaemia associated with reduced levels of total and high density lipoprotein (HDL)-cholesterol and a significant increase in the plasma ratio of unesterified to total cholesterol. Quantitative determination of plasma apolipoproteins revealed significantly decreased levels of all measured apolipoproteins, especially of apolipoproteins A-I and A-II, with the exception of apolipoprotein E, the levels of which were markedly increased. Moreover, at least two isoforms of the apolipoprotein serum amyloid A (SAA), an acute phase protein, were detected in all patients' plasma using two-dimensional electrophoresis. Immunochemical evidence was presented that apolipoproteins E and SAA, although both primarily associated with apolipoprotein A- (A-I and A-II) as well as with apolipoprotein B-containing lipoproteins, could occur as LP-E and LP-SAA subspecies, devoid of apolipoproteins A and B. However, it should be pointed out that LP-SAA particles were found in HDL2 from only two patients whereas the abnormal LP-E particles were detected in LDL and HDL2 from all investigated patients. The polydispersity and heterogeneity of patients' HDL3 were assessed by electron microscopy. It was further suggested that the profound changes in the lipoprotein metabolism of these young patients may be due to the increased hepatic synthesis of apolipoprotein SAA and/or to their altered immune function during active visceral Leishmaniasis.

Complicating systemic amyloidosis in dystrophic epidermolysis bullosa, recessive type

An autopsy case of dystrophic epidermolysis bullosa, recessive type, complicated by systemic secondary amyloidosis is described. The patient had developed multiple bullous lesions and erosions from birth, followed by repeated infection. At autopsy, chronic persistent inflammation was observed in the skin and in various visceral organs, accompanied by systemic amyloidosis. By the peroxidase-antiperoxidase (PAP) method, amyloid deposits stained positively for anti-AA-protein antiserum. In the present case, we concluded that the systemic amyloidosis was of the AA type, and developed secondarily to the chronic persistent inflammation in the prolonged course of dystrophic epidermolysis bullosa, recessive type.

Amyloidosis associated with juvenile rheumatoid arthritis

Clinical and pathological findings are reported in a Japanese girl who died of secondary amyloidosis associated with juvenile rheumatoid arthritis two years after the onset of symptoms. The patient had intermittent high fever, rheumatoid rash, polyarthralgia, and hepatosplenomegaly. The joints showed the typical histologic changes of juvenile rheumatoid arthritis. Amyloid deposition was found in various tissues; however, remarkable deposition of amyloid was observed in the gastrointestinal tract, especially in the ileum. The amyloid protein in this patient was identified as protein AA using the methods of potassium permanganate treatment and the peroxidase-antiperoxidase unlabeled antibody technique.

Gout and amyloidosis

Two patients with gout and amyloidosis are reported. In contrast with other forms of chronic arthritis gout is apparently not associated with an increased incidence of amyloidosis. The possible reasons for this exception are discussed.

Serum amyloid protein levels in south american children with rheumatoid arthritis: a co-operative study

Serum amyloid protein (SAA) levels were determined by radioimmunoassay in 90 children with juvenile rheumatoid arthritis (JRA). Significantly higher levels of SAA were present in children with the polyarticular and systemic forms of the disease. SAA levels correlate with disease activity, increasing during acute exacerbations, decreasing during remission and in patients having prednisone therapy. High serum SAA concentrations in children with JRA did not correlate with the presence of secondary amyloidosis and may be useful as a disease monitor.