21 agosto 2013
articolo postato il: 2013-08-21 22:33:08
Questa settimana proponiamo l`articolo di Paul Simons e colleghi pubblicato su PNAS a cui ha contribuito anche Patrizia Mangione del nostro gruppo e in cui è descritto il modello di amiloidosi A ottenuto sovra-esprimendo la proteina SAA, indipendentemente dallo stato di flogosi. Rappresenta un modello unico di amiloidosi sistemica utilissimo per capire il meccanismo naturale della malattia e per testare nuovi farmaci.
L`articolo completo e` disponibile su richiesta (VB)
Simons JP*,Al-Shawi R, Ellmerich S, Speck I, Aslam S, Hutchinson WL, Mangione PP, Disterer P, Gilbertson JA, Hunt T, Millar DJ, Minogue S, Bodin K, Pepys MB, Hawkins PN.
Proc Natl Acad Sci U S A. 2013 Aug 19.
*Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London NW3 2PF, United Kingdom.
Systemic amyloid A (AA) amyloidosis is a serious complication of chronic inflammation. Serum AA protein (SAA), an acute phase plasma protein, is deposited extracellularly as insoluble amyloid fibrils that damage tissue structure and function. Clinical AA amyloidosis is typically preceded by many years of active inflammation before presenting, most commonly with renal involvement. Using dose-dependent, doxycycline-inducible transgenic expression of SAA in mice, we show that AA amyloid deposition can occur independently of inflammation and that the time before amyloid deposition is determined by the circulating SAA concentration. High level SAA expression induced amyloidosis in all mice after a short, slightly variable delay. SAA was rapidly incorporated into amyloid, acutely reducing circulating SAA concentrations by up to 90%. Prolonged modest SAA overexpression occasionally produced amyloidosis after long delays and primed most mice for explosive amyloidosis when SAA production subsequently increased. Endogenous priming and bulk amyloid deposition are thus separable events, each sensitive to plasma SAA concentration. Amyloid deposits slowly regressed with restoration of normal SAA production after doxycycline withdrawal. Reinduction of SAA overproduction revealed that, following amyloid regression, all mice were primed, especially for rapid glomerular amyloid deposition leading to renal failure, closely resembling the rapid onset of renal failure in clinical AA amyloidosis following acute exacerbation of inflammation. Clinical AA amyloidosis rarely involves the heart, but amyloidotic SAA transgenic mice consistently had minor cardiac amyloid deposits, enabling us to extend to the heart the demonstrable efficacy of our unique antibody therapy for elimination of visceral amyloid.