Islet amyloid develops diffusely throughout the pancreas before becoming severe and replacing endocrine cells

Area of Science:

• Endocrinology
• Pathology
• Molecular Biology

Background:

• Islet amyloid, a hallmark of type 2 diabetes, is implicated in disease pathogenesis.
• The distribution and early effects of islet amyloidosis remain incompletely understood.

Purpose of the Study:

• To investigate the pancreatic distribution of islet amyloid.
• To determine if islet amyloid affects islet cell composition.
• To assess the relationship between amyloid severity and endocrine cell mass.

Main Methods:

• Utilized computerized fluorescence microscopy in transgenic mouse models.
• Quantified amyloid prevalence and severity across the pancreas.
• Analyzed islet endocrine cell proportions (beta, alpha, delta cells) in transgenic and non-transgenic mice.

Main Results:

• Islet amyloidosis demonstrated uniform prevalence and severity throughout the pancreas.
• Amyloid was detected in islets even at low severity (1.5% islet area), indicating early, diffuse distribution.
• Transgenic mice showed reduced proportions of beta-cells (62.9% vs 75.5%) and delta-cells (2.8% vs 4.4%) compared to controls.
• Amyloid severity was inversely correlated with beta-cell, alpha-cell, and delta-cell areas within individual islets.

Conclusions:

• Islet amyloidosis is a diffuse process affecting all islets uniformly from early stages.
• A reduction in islet endocrine cell mass begins early in amyloid development and worsens with increasing amyloid.
• These findings highlight the early and widespread impact of islet amyloidosis on pancreatic islet structure and function.