AA AMYLOSE
New monograph on AA amyloidosis published in the medical-surgical encyclopaedia (EMC) of nephrology
L. Savey, D. Buob, M. Delplanque, A. Terré, A. Fayand, R. Bourguiba, G. Grateau,S. Georgin-Lavialle
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Abstract
AA amyloidosis is one of the three major varieties of multisystem amyloidosis, along with AL amyloidosis and transthyretin amyloidosis (TTR). Prolonged inflammation is a prerequisite for the development of AA amyloidosis; the predominant protein in the deposits is a fragment of Serum Amyloid A (SAA) protein, one of the proteins involved in the inflammatory response. However, other factors, particularly genetic, are involved in the susceptibility to the development of AA amyloidosis. The kidney is the organ most frequently affected by AA amyloidosis. Proteinuria tests and blood creatinine measurements are therefore the main ways of detecting amyloidosis in any disease involving chronic inflammation. Precise diagnosis of AA amyloidosis requires comparison of all the clinical and histological data, particularly immunohistochemistry, so as not to confuse it with one of the other varieties. Current treatments are aimed at controlling inflammation, and therefore treating the causative disease when it has been identified, or a treatment targeting the cytokine inflammatory cascade, most often an anti-IL-1, or an anti-IL-6 when the cause of the inflammation remains unknown. Progression to end-stage renal failure or symptomatic digestive disease has a poor prognosis, and every effort must be made to avoid reaching these serious stages.
French practical guidelines for the diagnosis and management of AA amyloidosis
French recommendations for the management of AA amyloidosis
S. Georgin-Lavialle, L. Savey, D. Buob , J.-P. Bastard, S. Fellahi , A. Karras , J.-J. Boffa, G. Grateau & collaborators (see complete list in the PDF)
Sorbonne University, Internal medicine department, Tenon hospital, National reference center for autoinflamamtory diseases and AA amylodiosis (CEREMAIA), Paris;
Biochemistry department, Henri-Mondor hospital, Créteil, France;
Paris center university, Nephrology department, Georges Pompidou European hospital, Paris, France
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Abstract
AA amyloidosis is secondary to the deposit of excess insoluble Serum Amyloid A (SAA) protein fibrils. AA amyloidosis complicates chronic inflammatory diseases, especially chronic inflammatory rheumatisms such as rheumatoid arthritis and spondyloarthritis; chronic infections such as tuberculosis, bronchectasia, chronic inflammatory bowel diseases such as Crohn’s disease; and auto-inflammatory diseases including familial Mediterranean fever. This work consists of the French guidelines for the diagnosis workup and treatment of AA amyloidosis. We estimate in France between 500 and 700 cases in the whole French population, affecting both men and women. The most frequent organ impaired is kidney which usually manifests by oedemas of the lower extremities, proteinuria, and/or renal failure. Patients are usually tired and can display digestive features anf thyroid goiter. The diagnosis of AA amyloidosis is based on detection of amyloid deposits on a biopsy using Congo Red staining with a characteristic green birefringence in polarized light. Immunohistochemical analysis with an antibody directed against Serum Amyloid A protein is essential to confirm the diagnosis of AA amyloidosis. Peripheral inflammatory biomarkers can be measured such as C Reactive protein and SAA. We propose an algorithm to guide the etiological diagnosis of AA amyloidosis. The treatement relies on the etiologic treatment of the undelying chronic inflammatory disease to decrease and/or normalize Serum Amyloid A protein concentration in order to stabilize amyloidosis. In case of renal failure, dialysis or even a kidney transplant can be porposed. Nowadays, there is currently no specific treatment for AA amyloidosis deposits which constitutes a therapeutic challenge for the future. © 2022 L’Auteur(s). Publie´ par Elsevier Masson SAS au nom de Societ´ e´ Nationale Franc¸ aise de Medecine ´ Interne (SNFMI). Cet article est publie´ en Open Access sous licence CC BY-NC-ND (http:// creativecommons.org/licenses/by-nc-nd/4.0/).