Alzheimer’s disease (AD) is a prevalent neurodegenerative disorder. With the aging population and the continuous development of risk factors associated with AD, it will impose a significant burden on individuals, families, and society. Currently, commonly used therapeutic drugs such as Cholinesterase inhibitors, N-methyl-D-aspartate antagonists, and multiple AD pathology removal drugs have been shown to have beneficial effects on certain pathological conditions of AD. However, their clinical efficacy is minimal and they are associated with certain adverse reactions. Furthermore, the underlying pathological mechanism of AD remains unclear, posing a challenge for drug development. In contrast, natural plant molecules, widely available, offer multiple targeting pathways and demonstrate inherent advantages in modifying the typical pathologic features of AD by influencing the blood–brain barrier (BBB). We provide a comprehensive review of recent in vivo and in vitro studies on natural plant molecules that impact the BBB in the treatment of AD. Additionally, we analyze their specific mechanisms to offer novel insights for the development of safe and effective targeted drugs as well as guidance for experimental research and the clinical application of drugs for the prevention and treatment of AD.

Diabetes mellitus comprises a group of heterogeneous metabolic disorders characterized by persistent hyperglycemia, progressive β-cell dysfunction, and multi-organ complications. Although type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have distinct pathogenic origins, both involve immune dysregulation, tissue stress, release of danger signals, and chronic inflammation. Dendritic cells (DCs), as antigen-presenting cells, integrate innate immune sensing, antigen presentation, cytokine production, T-cell regulation, and peripheral immune tolerance, placing them at a critical interface between autoimmunity and metabolic inflammation. In T1DM, DCs contribute to β-cell autoantigen presentation, tolerance breakdown, autoreactive T-cell activation, and insulitis amplification. In T2DM, DCs may contribute to adipose tissue inflammation, hepatic immunometabolic crosstalk, β-cell stress, vascular inflammation, and immune remodeling associated with diabetes-related complications. Here, we review the disease-specific roles of DC subsets in T1DM and T2DM and discuss shared molecular mechanisms, including pattern-recognition receptor signaling, metabolic reprogramming, inflammasome activation, cytokine networks, and the shift from immune tolerance to inflammation. We also evaluate therapeutic DC reprogramming strategies and their potential implications for targeted immunometabolic intervention in diabetes.