Molecular Mechanisms of Cardiac Amyloidosis.
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ABSTRACT:
SUBMITTER: Saito Y
PROVIDER: S-EPMC8744761 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Systemic amyloidosis is caused by misfolding and extracellular deposition of circulating proteins as amyloid fibrils, resulting in the dysfunction of vital organs. The most common systemic amyloidosis, light-chain (AL) amyloidosis, is caused by misfolded light chains produced by a small, dangerous B-cell clone. The process of amyloid formation, organ targeting, and damage is multifaceted and, after disease initiation, the complexity of the downstream pathogenic cascade increases, rendering its control a challenge. Because of the progressive nature of the disease, early diagnosis to prevent end-stage organ damage is vital. Improving awareness and systematic use of biomarkers of organ damage in screening populations at risk may improve the still unsatisfactory diagnostic process. Amyloid imaging is now emerging as an important companion of biomarkers in formulating the diagnosis and prognosis and monitoring the effects of therapy. An accurate diagnosis is the basis for appropriate therapy that is risk-adapted and response-tailored. Effective treatments targeting the clone and rapidly and profoundly reducing the amyloid light chains have produced marked improvements in overall survival, making AL amyloidosis the most successful model of all amyloidoses. New therapies targeting the amyloid deposits are now under development, together with novel agents modulating light chain aggregation and proteotoxicity. The future of AL amyloidosis treatment is combination therapy and will require an innovative collaborative model for a rapid translation from bench to bedside with the ultimate aim of achieving a cure for this complex disease.
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Project description:Elevated pro-inflammatory biomarkers and cytokines are associated with morbidity and mortality in heart failure (HF). Preclinical and clinical studies have shown multiple inflammatory mechanisms causing cardiac remodeling, dysfunction and chronic failure. Therapeutics in trials targeting the immune response in heart failure and its effects did not result in evident benefits regarding clinical endpoints and mortality. This review elaborates pathways of immune cytokines in pathogenesis and worsening of heart failure in clinical and cellular settings. Besides the well-known mechanisms of immune activation and inflammation in atherosclerosis causing ischemic cardiomyopathy or myocarditis, attention is focused on other mechanisms leading to heart failure such as transthyretin (TTR) amyloidosis or heart failure with preserved ejection fraction. The knowledge of the pathogenesis in heart failure and amyloidosis on a molecular and cellular level might help to highlight new disease defining biomarkers and to lead the way to new therapeutic targets.
| S-EPMC6540104 | biostudies-literature
Project description:Cardiac amyloidosis (CA) is a heterogeneous group of diseases in which extracellular insoluble amyloid proteins are deposited in specific organs and tissues locally or systemically, thereby interfering with physiological function. Transthyretin protein (TTR) and light chain (AL) amyloidosis are the most common types of cardiac amyloidosis. Radionuclide bone scintigraphy has recently become the most common non-invasive test for the diagnosis of TTR-CA but is of limited value for the diagnosis of AL-CA. PET has proved promising for the diagnosis of CA and its applications are expected to expand in the future. This review summarizes the current bone scintigraphy and amyloid-targeting Positron emission tomography (PET) imaging, the binding imaging properties of radiotracers, and the values of diagnosis, prognosis, and monitoring therapy response in CA.
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Project description:Cardiac amyloidosis is a form of restrictive cardiomyopathy resulting in heart failure and potential risk on arrhythmia, due to amyloid infiltration of the nerve conduction system and the myocardial tissue. The prognosis in this progressive disease is poor, probably due the development of cardiac arrhythmias. Early detection of cardiac sympathetic innervation disturbances has become of major clinical interest, because its occurrence and severity limits the choice of treatment. The use of iodine-123 labelled metaiodobenzylguanidine ([I-123]MIBG), a chemical modified analogue of norepinephrine, is well established in patients with heart failure and plays an important role in evaluation of sympathetic innervation in cardiac amyloidosis. [I-123]MIBG is stored in vesicles in the sympathetic nerve terminals and is not catabolized like norepinephrine. Decreased heart-to-mediastinum ratios on late planar images and increased wash-out rates indicate cardiac sympathetic denervation and are associated with poor prognosis. Single photon emission computed tomography provides additional information and has advantages for evaluating abnormalities in regional distribution in the myocardium. [I-123]MIBG is mainly useful in patients with hereditary and wild-type ATTR cardiac amyloidosis, not in AA and AL amyloidosis. The potential role of positron emission tomography for cardiac sympathetic innervation in amyloidosis has not yet been identified.
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Project description:Amyloidosis refers to a range of protein misfolding disorders that can cause organ dysfunction through progressive fibril deposition. Cardiac involvement often leads to significant morbidity and mortality and increasingly has been recognized as an important cause of heart failure. The two main forms of cardiac amyloidosis, light chain (AL) and transthyretin (ATTR) amyloidosis, have distinct mechanisms of pathogenesis. Recent insights have led to the development of novel pharmacotherapies with the potential to significantly impact each disease. This review will summarize the preclinical and clinical data for these emerging treatments for AL and ATTR amyloidosis.
| S-EPMC5832446 | biostudies-literature
Project description:AimsCardiac resynchronization therapy (CRT) is highly effective in dilated cardiomyopathy (DCM) patients with impaired left ventricular ejection fraction (LVEF) and left bundle block branch. In cardiac amyloidosis (CA) patients, left ventricular dysfunction and conduction defects are common, but the potential of CRT to improve cardiac remodelling and survival in this particular setting remains undefined. We investigated cardiovascular outcomes in CA patients after CRT implantation in terms of CRT echocardiographic response and major cardiovascular events (MACEs).Methods and resultsOur retrospective study included 47 CA patients implanted with CRT devices from January 2012 to February 2020, in nine French university hospitals (77 ± 6 years old, baseline LVEF 30 ± 8%) compared with propensity-matched (1:1 for age, LVEF at implantation, and CRT indication) DCM patients with a CRT device. CA patients had lower rates of CRT response (absolute delta LVEF ≥ 10%) compared with DCM patients (36% vs. 70%, P = 0.002). After multivariate Cox analysis, CA was independently associated with MACE (hospitalization for heart failure/cardiovascular death) [hazard ratio (HR) 3.73, 95% confidence interval (CI) 1.85-7.54, P < 0.001], along with the absence of CRT response (HR 3.01, 95% CI 1.56-5.79, P = 0.001). The presence of echocardiographic CRT response (absolute delta LVEF ≥ 10%) was the only predictive factor of MACE-free survival in CA patients (HR 0.36, 95% CI 0.15-0.86, P = 0.002).ConclusionCompared with a matched cohort of DCM patients, CA patients had a lower rate of CRT response and consequently a worse cardiovascular prognosis after CRT implantation. However, CRT could be beneficial even in CA patients given that CRT response was associated with better cardiac outcomes in this population.
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Project description: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.
| S-EPMC3791773 | biostudies-literature
Project description:Cardiac amyloidosis can result from any of the systemic amyloidoses. The disease is often characterized by a restrictive cardiomyopathy although the particular signs and symptoms depend in part on the underlying cause. In addition to managing the symptoms of heart failure, treatment options vary depending on the etiology of amyloid deposition. It is therefore critical to identify the cause of cardiac amyloidosis before initiating definitive therapy. We present a patient with presumed immunoglobulin (AL) amyloidosis who had a circulating lambda monoclonal protein, but a bone marrow biopsy with kappa predominant plasma cells. This unusual finding called into question the diagnosis of AL amyloidosis and highlights the importance and difficulty of determining the cause of cardiac amyloid deposition before initiating treatment. We review the different forms of cardiac amyloidosis and propose a diagnostic algorithm to help identify the etiology of cardiac amyloid deposition before beginning therapy.
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