Triggering receptor expressed on myeloid cells 2 (TREM2) is a single-pass transmembrane immune receptor that is mainly expressed on microglia in the brain and macrophages in the periphery. Recent studies have identified TREM2 as a risk factor for Alzheimer’s disease (AD). Increasing evidence has shown that TREM2 can affect lipid metabolism both in the central nervous system (CNS) and in the periphery. In the CNS, TREM2 affects the metabolism of cholesterol, myelin, and phospholipids and promotes the transition of microglia into a disease-associated phenotype. In the periphery, TREM2 influences lipid metabolism by regulating the onset and progression of obesity and its complications, such as hypercholesterolemia, atherosclerosis, and nonalcoholic fatty liver disease. All these altered lipid metabolism processes could influence the pathogenesis of AD through several means, including affecting inflammation, insulin resistance, and AD pathologies. Herein, we will discuss a potential pathway that TREM2 mediates lipid metabolism to influence the pathogenesis of AD in both the CNS and periphery. Moreover, we discuss the possibility that TREM2 may be a key factor that links central and peripheral lipid metabolism under disease conditions, including AD. This link may be due to impacts on the integrity of the blood–brain barrier, and we introduce potential pathways by which TREM2 affects the blood–brain barrier. Moreover, we discuss the role of lipids in TREM2-associated treatments for AD. We propose some potential therapies targeting TREM2 and discuss the prospect and limitations of these therapies.

Synapses are key structures involved in transmitting information in the nervous system, and their functions rely on the regulation of various lipids. Lipids play important roles in synapse formation, neurotransmitter release, and signal transmission, and dysregulation of lipid metabolism is closely associated with various neurodegenerative diseases. The complex roles of lipids in synaptic function and neurological diseases have recently garnered increasing attention, but their specific mechanisms remain to be fully understood. This review aims to explore how lipids regulate synaptic activity in the central nervous system, focusing on their roles in synapse formation, neurotransmitter release, and signal transmission. Additionally, it discusses the mechanisms by which glial cells modulate synaptic function through lipid regulation. This review shows that within the central nervous system, lipids are essential components of the cell membrane bilayer, playing critical roles in synaptic structure and function. They regulate presynaptic vesicular trafficking, postsynaptic signaling pathways, and glial–neuronal interactions. Cholesterol maintains membrane fluidity and promotes the formation of lipid rafts. Glycerophospholipids contribute to the structural integrity of synaptic membranes and are involved in the release of synaptic vesicles. Sphingolipids interact with synaptic receptors through various mechanisms to regulate their activity and are also involved in cellular processes such as inflammation and apoptosis. Fatty acids are vital for energy metabolism and the synthesis of signaling molecules. Abnormalities in lipid metabolism may lead to impairments in synaptic function, affecting information transmission between neurons and the overall health of the nervous system. Therapeutic strategies targeting lipid metabolism, particularly through cholesterol modulation, show promise for treating these conditions. In neurodegenerative diseases such as Alzheimer’s disease, Parkinson disease, and amyotrophic lateral sclerosis, dysregulation of lipid metabolism is closely linked to synaptic dysfunction. Therefore, lipids are not only key molecules in neural regeneration and synaptic repair but may also contribute to neurodegenerative pathology when metabolic dysregulation occurs. Further research is needed to elucidate the specific mechanisms linking lipid metabolism to synaptic dysfunction and to develop targeted lipid therapies for neurological diseases.

Background: Mutations in the mitochondrial alanyl‐transfer (t)RNA synthetase 2 (AARS2,OMIM:612035) have been linked to leukoencephalopathy recently. Till now, there have been 19 cases reported so far. However, the clinical and genetic characteristics of this disease are not fully understood. We reported an adult‐onset male leukoencephalopathy patient related to novel AARS2 gene mutations and reviewed all previous cases regarding the clinical and genetic features of AARS2 leukoencephalopathy.Methods: The spectrum of clinical symptoms and the genetic analysis of the presented patient were identified and investigated. Besides this case, we assessed previously reported cases with AARS2 gene mutations.Results: Here, we present a 30‐year‐old man with progressive motor deficits in the right lower limb and severe cerebellar ataxia for one year. MRI revealed extensive white matter lesions in periventricular regions and along the corticospinal tract. Genetic analysis revealed two new heterogeneous missense mutations in AARS2: c.179C>A and c.1703_1704del. We described the ragged red fiber (RRF) for the first time, suggesting that AARS2‐related leukoencephalopathy be a new variant of mitochondrial encephalomyopathy. Gradual improvement in motor function was observed with intravenous coenzyme complex treatment. We also summarized our case and all previously reported cases to provide an overview of AARS2‐related late‐onset leukoencephalopathy. Then, we compared clinical and neuroimaging features of AARS2‐related leukoencephalopathy with three other frequently diagnosed types of adult‐onset leukoencephalopathy to provide insight into diagnostic strategies.Conclusion: The characteristic MRI abnormalities and clinical symptoms described here may help to distinguish AARS2‐related leukoencephalopathy from other adult‐onset leukoencephalopathies. The combination of encephalopathy and myopathy strongly suggest that AARS2‐related leukoencephalopathy is a new variant of mitochondrial encephalomyopathy. The response to coenzyme complex will shed light on future therapy investigation.