Single-cell atlas reveals the key role of pro-inflammatory IREB2⁺ microglia subsets in the microenvironment of Alzheimer's disease.

Chronic neuroinflammation driven by activated microglia is a critical hallmark of Alzheimer's disease (AD) progression. Metabolic dysregulation, particularly iron metabolism, has been implicated in neurodegeneration, yet the role of iron-responsive element-binding protein 2 (IREB2) in AD-associated neuroinflammation remains poorly understood. We performed integrative analysis of single-cell RNA sequencing (scRNA-seq) data from AD brain tissues, using non-negative matrix factorization (NMF) and intercellular communication algorithms to map cellular landscapes. We identified microglial subpopulations and their inflammatory signaling. To experimentally validate the functional role of IREB2 in inflammatory responses, we conducted siRNA-mediated knockdown in the human neuroblastoma cell line SH-SY5Y, which serves as a neuronal model for assessing IREB2's effect on cytokine expression. Single-cell analysis revealed a distinct microglial subpopulation (IREB2⁺ MC C1) that is significantly expanded in AD. This subpopulation exhibits a hyper-inflammatory state, with enrichment of Toll-like receptor and IL-17 signaling pathways, and functions as a primary source of outgoing inflammatory signals (CCL3, CCL4). Furthermore, IREB2 knockdown in SH-SY5Y cells significantly suppressed the expression of key pro-inflammatory cytokines (IL6, IL-1β, and TNF-α), confirming that IREB2 positively regulates inflammation in neurons as well. IREB2 drives both microglial activation and neuronal inflammatory responses in AD, potentially via the NF-κB pathway. The IREB2⁺ microglial subpopulation represents a specific pathogenic entity that orchestrates the inflammatory microenvironment. Targeting IREB2 may therefore offer a dual-pronged therapeutic strategy to mitigate neuroinflammation and slow AD progression.