This review provides an overview of the role of microglia in the formation of amyloid beta (Aβ) plaques, the primary pathological feature of Alzheimer's disease (AD). Microglia, the brain's resident immune cells, play a crucial role in Aβ plaque formation through various mechanisms, including phagocytosis, inflammatory responses, and the regulation of Aβ levels. The review highlights the complex and dynamic nature of microglial responses, which can be both protective and detrimental depending on the stage of AD progression. Key findings include: 1. **Microglial Role in Aβ Plaque Formation**: - Microglia are involved in the early elimination of Aβ through phagocytosis. - In later stages, microglia contribute to plaque compaction and barrier formation, potentially preventing neuronal damage. - The ability of microglia to envelope Aβ deposits is associated with the severity of neuritic dystrophy. 2. **Mechanisms of Microglial Action**: - Microglia internalize Aβ via receptors such as TREM2 and TAMs, which can lead to lysosomal damage and the activation of the NLRP3 inflammasome. - Inflammasome activation can amplify Aβ plaque accumulation, while anti-inflammatory responses can mitigate it. - ApoE, a lipid-binding protein, plays a role in modulating Aβ metabolism and microglial responses. 3. **Influence of Genetic and Environmental Factors**: - Genetic variants, particularly those affecting TREM2 function, significantly influence microglial responses and AD progression. - Environmental factors, such as viral infections, can also impact microglial activity and Aβ plaque formation. 4. **Therapeutic Implications**: - Anti-Aβ immunotherapies aim to enhance microglial phagocytosis and reduce Aβ levels. - Stimulation of TREM2 with agonistic antibodies has shown promise in reducing Aβ plaque deposition and improving cognitive function. 5. **Challenges and Future Directions**: - Further research is needed to understand the dynamic interactions between microglia and Aβ plaques at different stages of AD. - Developing novel model systems, such as human-induced pluripotent stem cell-derived models, can help bridge the gap between mouse and human AD research. - Functional characterization of different Aβ aggregates and their impact on microglial activity will enhance our understanding of the complex role of microglia in AD. Overall, the review underscores the critical role of microglia in Aβ plaque formation and highlights the need for a deeper understanding of their mechanisms to develop effective therapeutic strategies for AD.This review provides an overview of the role of microglia in the formation of amyloid beta (Aβ) plaques, the primary pathological feature of Alzheimer's disease (AD). Microglia, the brain's resident immune cells, play a crucial role in Aβ plaque formation through various mechanisms, including phagocytosis, inflammatory responses, and the regulation of Aβ levels. The review highlights the complex and dynamic nature of microglial responses, which can be both protective and detrimental depending on the stage of AD progression. Key findings include: 1. **Microglial Role in Aβ Plaque Formation**: - Microglia are involved in the early elimination of Aβ through phagocytosis. - In later stages, microglia contribute to plaque compaction and barrier formation, potentially preventing neuronal damage. - The ability of microglia to envelope Aβ deposits is associated with the severity of neuritic dystrophy. 2. **Mechanisms of Microglial Action**: - Microglia internalize Aβ via receptors such as TREM2 and TAMs, which can lead to lysosomal damage and the activation of the NLRP3 inflammasome. - Inflammasome activation can amplify Aβ plaque accumulation, while anti-inflammatory responses can mitigate it. - ApoE, a lipid-binding protein, plays a role in modulating Aβ metabolism and microglial responses. 3. **Influence of Genetic and Environmental Factors**: - Genetic variants, particularly those affecting TREM2 function, significantly influence microglial responses and AD progression. - Environmental factors, such as viral infections, can also impact microglial activity and Aβ plaque formation. 4. **Therapeutic Implications**: - Anti-Aβ immunotherapies aim to enhance microglial phagocytosis and reduce Aβ levels. - Stimulation of TREM2 with agonistic antibodies has shown promise in reducing Aβ plaque deposition and improving cognitive function. 5. **Challenges and Future Directions**: - Further research is needed to understand the dynamic interactions between microglia and Aβ plaques at different stages of AD. - Developing novel model systems, such as human-induced pluripotent stem cell-derived models, can help bridge the gap between mouse and human AD research. - Functional characterization of different Aβ aggregates and their impact on microglial activity will enhance our understanding of the complex role of microglia in AD. Overall, the review underscores the critical role of microglia in Aβ plaque formation and highlights the need for a deeper understanding of their mechanisms to develop effective therapeutic strategies for AD.