Unraveling the Mystery of IAPP Amyloids: How 'Aged' Protein Plaques Impact Toxicity and Disease
"New research sheds light on how the characteristics of human islet amyloid polypeptide (IAPP) amyloids change over time, impacting their toxicity and potential role in diseases like type 2 diabetes."
For years, scientists have been intensely studying amyloid proteins, particularly their role in diseases like Alzheimer's and type 2 diabetes. These proteins, when misfolded, aggregate into structures known as amyloid fibrils, which are believed to contribute to cellular damage. While much is understood about the initial stages of fibril formation, less is known about how these fibrils change as they age and whether those changes alter their impact on the body.
A new study published in Science Bulletin is diving deeper into this question, specifically focusing on human islet amyloid polypeptide (IAPP) amyloids. IAPP is a protein found in the pancreas that, when misfolded, forms amyloid plaques associated with the development of type 2 diabetes. The researchers sought to understand how the physical and toxicological properties of these IAPP amyloids evolve over time.
This article breaks down the key findings of this research, explaining how the characteristics of IAPP amyloids change as they 'age,' how these changes influence their toxicity and ability to seed new amyloid formations, and what this all means for potential therapeutic strategies. Ultimately, this research suggests that understanding the long-term behavior of amyloid plaques is crucial for tackling related diseases.
IAPP Oligomerization and Diabetes
Islet amyloid polypeptide (IAPP), also called amylin, is a 37-amino-acid peptide co-secreted with insulin by pancreatic beta cells. In type 2 diabetes, IAPP oligomerization is regarded as a disease-driving force, and misfolded IAPP can aggregate into amyloid fibrils within pancreatic islets. The available source material does not provide a prevalence figure or a measured estimate of IAPP oligomer levels in patients, so it does not establish a population-wide statistic for IAPP-related impact.
Fibril Structures and Unresolved Mechanisms
Human IAPP forms amyloid deposits in the islets of people with type 2 diabetes, and fibrils are considered relevant to disease pathogenesis. A 2026 study determined a cryo-electron microscopy structure of patient-derived hIAPP fibrils, providing structural information about those deposits. However, the precise mechanisms by which IAPP contributes to beta-cell death and disease remain uncertain, as noted in a 2018 review.
The Changing Face of Amyloids: What Happens as They Age?
The research team aged IAPP fibrils for up to two months and then examined their physical and biological properties. Surprisingly, they found that as IAPP fibrils aged, their toxicity actually decreased. This was an unexpected finding, as many assume amyloid plaques become more harmful over time.
- Atomic Force Microscopy: Used to probe the mechanical properties of IAPP fibrils at different ages, revealing comparable stiffness but age-dependent fragmentation.
- Sonication: Fibrils were broken down using sound waves, and the resulting fragments self-assembled into large lamellar structures, the largest reported to date.
- Blue-Native PAGE: This technique showed that older IAPP amyloids had an increased capacity to bind to other proteins, which might explain their ability to sequester fresh IAPP.
Aggregation Kinetics and Toxic Species
A 2026 report, “Lag phase length of IAPP amyloid formation predicts the duration of β-cell toxicity,” states that maximal toxicity occurs during the lag phase of amyloid formation and proposes aggregation kinetics as a framework for predicting when IAPP proteotoxicity begins and how long it lasts. Separately, a study of DNA nanostructures reports that they can prevent toxic amyloid proteospecies from forming and convert them into cytocompatible, biodegradable spherical complexes. A review snippet also describes hIAPP homo-hexamers as aggregation-competent species discussed in relation to early beta-cell damage and possible diagnostic or therapeutic targets.
Established Toxicity, Unsettled Disease Role
A review states that IAPP oligomers and amyloid plaques are present in beta cells of people with type 2 diabetes, and that cytoplasmic IAPP oligomers are toxic in cellular systems and animal models. A separate review identifies islet amyloid deposits, whose major component is IAPP, as a significant pathological change in type 2 diabetes. These observations support a link between IAPP aggregation and beta-cell pathology, while the sources do not establish that the deposits alone explain the full course of the disease.
Structural Insights and Dual-Targeting Proposal
A 2020 report describes three recent studies that used cryo-electron microscopy to determine structures of IAPP amyloid fibrils linked to type 2 diabetes pathogenesis. The report says these structures shed light on the fibrils, but its supplied summary does not provide specific structural differences among the studies. A 2025 article proposes exploring dual inhibitors of amyloid-β42 and IAPP as a possible approach for Alzheimer’s disease in people with type 2 diabetes, motivated by limitations of current treatments in addressing IAPP’s proposed role in Alzheimer’s progression.
Implications for Future Treatments: A New Perspective on Amyloid Diseases
This research provides a new perspective on the role of amyloid plaques in diseases like type 2 diabetes. The finding that aged IAPP amyloids can sequester toxic IAPP and reduce its harmful effects suggests that targeting these plaques might not always be the best approach.
Prion-Like Transmission in Models
Mukherjee and colleagues reported that pathological and clinical alterations of type 2 diabetes could be induced in vitro and in vivo through prion-like transmission of misfolded IAPP aggregates. The finding supports a role for IAPP aggregation in the disease processes examined. The supplied source summary does not specify how frequently such transmission occurs in people or establish its contribution to diabetes across the broader population.
Amylin in Human Diabetes
Human islet amyloid polypeptide, or amylin, is co-secreted with insulin from pancreatic beta cells. The 2023 source describes hIAPP’s ability to aggregate in pancreatic islet cells in type 2 diabetes mellitus. This connects a hormone normally released alongside insulin with the amyloid deposits discussed in the context of human diabetes, although the supplied summary does not quantify effects on patients’ daily lives.
Instead, future therapies might focus on preventing the initial misfolding and aggregation of IAPP, or on enhancing the ability of aged plaques to sequester toxic IAPP. Understanding the dynamic structural and toxicity profiles of amyloid fibrils and plaques, as this study highlights, is crucial for developing effective treatments.
While this study focused on IAPP amyloids in type 2 diabetes, the researchers suggest that the findings may be applicable to other amyloid proteins and related diseases, such as Alzheimer's. Further research is needed to fully understand the implications of these findings, but this study represents an important step forward in unraveling the complexities of amyloid diseases.