Apoptotic β-cells induce macrophage reprogramming under diabetic conditions

Area of Science:

• Immunology
• Endocrinology
• Metabolic Diseases

Background:

• Type 2 diabetes mellitus (T2DM) involves pancreatic beta-cell dysfunction and insulin resistance.
• Macrophages typically perform anti-inflammatory efferocytosis (clearing dead cells), but paradoxically contribute to T2DM inflammation.
• The impact of apoptotic beta-cells on macrophage function in T2DM is not well understood.

Purpose of the Study:

• To investigate how phagocytosis of apoptotic beta-cells influences macrophage function in the context of T2DM.
• To explore the mechanisms by which efferocytosis of apoptotic beta-cells contributes to inflammation in T2DM.

Main Methods:

• Examined macrophage responses to apoptotic beta-cells under diabetic conditions.
• Assessed lysosomal permeabilization, reactive oxygen species generation, and inflammasome activation in macrophages.
• Investigated lipid accumulation and foam cell-like transformation in islet macrophages.

Main Results:

• Phagocytosis of apoptotic beta-cells induced lysosomal permeabilization and reactive oxygen species production in macrophages.
• This process led to inflammasome activation and cytokine secretion, promoting inflammation.
• Efferocytosis resulted in lipid accumulation, transforming islet macrophages into foam cell-like cells, distinct from atherosclerosis.

Conclusions:

• Macrophages, while normally anti-inflammatory, undergo proinflammatory reprogramming as T2DM progresses due to increased demand for clearing apoptotic beta-cells.
• This shift in macrophage inflammatory response contributes to chronic inflammation in metabolic diseases like T2DM.
• Maintaining macrophage lysosomal function is a potential therapeutic strategy to mitigate T2DM progression.