Proteostasis-Restoring Therapies for Multiorgan Protein-Folding Disorders

Abstract

Disorders of protein folding, collectively known as proteopathies, are increasingly recognized as central contributors to a broad range of multiorgan diseases. The disruption of proteostasis—cellular mechanisms that maintain protein homeostasis—leads to the accumulation of misfolded proteins, cellular dysfunction, and tissue damage. This review examines the burden, mechanisms, clinical features, diagnostic challenges, and contemporary management strategies of multiorgan protein-folding disorders, with a focus on emerging proteostasis-restoring therapies. We discuss the latest scientific evidence, clinical trial updates, and guideline recommendations, providing clinicians and researchers with a comprehensive synthesis of this rapidly evolving field.

Introduction

Protein folding disorders, or proteopathies, encompass a spectrum of diseases characterized by the accumulation of abnormally folded proteins within cells, ultimately disrupting organ function. While neurodegenerative diseases are classic examples, systemic manifestations—such as amyloidoses and certain lysosomal storage disorders—demonstrate that proteostasis failure can have multiorgan implications. Understanding the molecular underpinnings and clinical consequences of proteostasis imbalance has propelled the development of novel therapeutic strategies aimed at restoring protein homeostasis. This review synthesizes current knowledge and highlights advances in proteostasis-restoring therapies relevant to multiorgan protein-folding disorders.

Epidemiology / Disease Burden

The epidemiology of protein-folding disorders varies with etiology and organ involvement. Systemic amyloidoses, such as AL (light-chain) and ATTR (transthyretin) amyloidosis, have an estimated incidence of 8–12 per million annually, though prevalence is likely underestimated due to diagnostic challenges. Lysosomal storage disorders, including Fabry and Gaucher diseases, affect 1 in 40,000–60,000 live births. Multiorgan proteinopathies often present in mid-to-late adulthood, though pediatric-onset forms exist. The burden is compounded by delayed diagnosis, progressive organ dysfunction, and the need for complex multidisciplinary care. Mortality and morbidity are high, particularly in cardiac and renal involvement, impacting quality of life and healthcare resources.

Pathophysiology

Proteostasis refers to the integrated network of cellular pathways that control protein synthesis, folding, trafficking, and degradation. Disruption of proteostasis may result from genetic mutations (e.g., misfolding-prone proteins), impaired chaperone function, oxidative stress, or age-related decline in quality control systems. Misfolded proteins evade degradation, aggregate, and exert cytotoxic effects through multiple mechanisms: disruption of cellular architecture, induction of endoplasmic reticulum (ER) stress, activation of inflammatory cascades, and interference with vital cellular processes. In amyloidoses, extracellular fibril deposition can cause tissue stiffness and organ failure, while intracellular accumulations in lysosomal storage diseases compromise cell viability across multiple systems.

Risk Factors

Risk factors for multiorgan protein-folding disorders are diverse. Genetic predisposition plays a central role, with pathogenic mutations in genes encoding for amyloidogenic or lysosomal proteins. Advancing age increases susceptibility due to cumulative wear on proteostasis mechanisms. Environmental triggers, such as oxidative or metabolic stress, can exacerbate protein misfolding. Chronic inflammation, comorbidities (e.g., chronic kidney disease, diabetes), and certain medications may further compromise protein homeostasis. Family history and specific ethnic backgrounds may also influence risk, particularly in hereditary amyloidoses and storage disorders.

Clinical Features

Clinical manifestations reflect the organs affected by protein aggregation. Cardiac involvement can present as restrictive cardiomyopathy, arrhythmias, or heart failure. Renal symptoms include proteinuria and progressive renal insufficiency. Neurologic findings range from peripheral neuropathy to autonomic dysfunction and cognitive decline. Hepatic, gastrointestinal, musculoskeletal, and dermatologic signs may also be present. The clinical course is often insidious, with nonspecific symptoms preceding overt organ dysfunction. Multisystem involvement, such as in systemic amyloidosis or Fabry disease, necessitates a high index of suspicion and comprehensive evaluation.

Diagnosis

Diagnosis of multiorgan protein-folding disorders is challenging. It relies on a combination of clinical assessment, laboratory testing, imaging, and tissue biopsy. Biomarkers such as serum free light chains, NT-proBNP, troponins, and genetic testing aid in subtype differentiation and risk stratification. Imaging modalities—including echocardiography, cardiac MRI, and bone scintigraphy—assess organ involvement and amyloid deposition. Histopathological confirmation, often via Congo red staining and immunohistochemistry, remains the gold standard for amyloidoses. Enzyme assays and genetic analysis are critical in lysosomal storage disorders. Early, accurate diagnosis is essential for optimal management and prognosis.

Treatment & Management

Management strategies are tailored to the underlying disorder and extent of organ involvement. Supportive care addresses heart failure, renal dysfunction, neuropathic pain, and other complications. Disease-modifying therapies aim to reduce the production or enhance clearance of misfolded proteins. In AL amyloidosis, plasma cell-directed chemotherapy is standard, while tafamidis, diflunisal, and patisiran are used in transthyretin amyloidosis. Enzyme replacement therapy (ERT) and chaperone therapies are established for several lysosomal storage disorders. Multidisciplinary care, encompassing cardiology, nephrology, neurology, and genetics, is crucial for comprehensive management.

Recent Advances / Emerging Therapies

Recent years have witnessed significant progress in proteostasis-restoring therapies. Small molecule pharmacological chaperones, such as migalastat for Fabry disease, stabilize native protein conformations and facilitate proper trafficking. Gene-silencing agents, including siRNA (patisiran) and antisense oligonucleotides (inotersen), reduce pathogenic protein synthesis in hereditary amyloidoses. Proteasome enhancers and autophagy inducers are under investigation for their ability to augment clearance of misfolded proteins. Monoclonal antibodies (e.g., CAEL-101) targeting amyloid deposits offer promise in reversing organ dysfunction. Advances in gene editing and stem cell therapies hold long-term potential for correcting underlying genetic defects and restoring proteostasis at the source.

Guideline Recommendations

Recent guidelines from professional societies underscore the importance of early recognition, multidisciplinary evaluation, and individualized therapy. The American Heart Association and European Society of Cardiology recommend genetic testing, biomarker profiling, and imaging for suspected cardiac amyloidosis. Consensus statements emphasize prompt initiation of disease-modifying therapies and routine monitoring for treatment response and adverse effects. For lysosomal storage disorders, guidelines advocate for early initiation of ERT or pharmacologic chaperones to prevent irreversible organ damage. Patient education, genetic counseling, and psychosocial support are integral components of comprehensive care.

Conclusion

Multiorgan protein-folding disorders represent a complex and expanding domain within internal medicine, with proteostasis restoration emerging as a central therapeutic paradigm. Advances in molecular understanding have translated into novel therapies that address the root causes of proteopathies, with significant implications for patient outcomes. Ongoing research, clinical trials, and collaborative guideline development are advancing the standard of care, offering hope for improved quality of life and survival in affected individuals. Continued efforts in early detection, personalized medicine, and translational research are essential to fully realize the potential of proteostasis-restoring therapies in the management of these challenging diseases.