Department of Internal Medicine, Raymond G. Murphy VA Medical Center, Albuquerque, NM, USA; Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA.
The Mind Research Network/Lovelace Biomedical and Environmental Research Institute.
Brain Behav Immun. 2024 Nov;122:345-352. doi: 10.1016/j.bbi.2024.08.034. Epub 2024 Aug 18.
Neuroinflammation is a key component underlying multiple neurological disorders, yet non-invasive and cost-effective assessment of in vivo neuroinflammatory processes in the central nervous system remains challenging. Diffusion weighted magnetic resonance spectroscopy (dMRS) has shown promise in addressing these challenges by measuring diffusivity properties of different neurometabolites, which can reflect cell-specific morphologies. Prior work has demonstrated dMRS utility in capturing microglial reactivity in the context of lipopolysaccharide (LPS) challenges and serious neurological disorders, detected as changes of microglial metabolite diffusivity properties. However, the extent to which such dMRS metrics are capable of detecting subtler and more nuanced levels of neuroinflammation in populations without overt neuropathology is unknown. Here we examined the relationship between intrinsic, gut-derived levels of systemic LPS and dMRS-based apparent diffusion coefficients (ADC) of choline, creatine, and N-acetylaspartate (NAA) in two brain regions: the thalamus and the corona radiata. Higher plasma LPS concentrations were significantly associated with increased ADC of choline and NAA in the thalamic region, with no such relationships observed in the corona radiata for any of the metabolites examined. As such, dMRS may have the sensitivity to measure microglial reactivity across populations with highly variable levels of neuroinflammation, and holds promising potential for widespread applications in both research and clinical settings.
神经炎症是多种神经疾病的关键组成部分，但在中枢神经系统中对体内神经炎症过程进行非侵入性和具有成本效益的评估仍然具有挑战性。扩散加权磁共振波谱（dMRS）通过测量不同神经代谢物的扩散特性来显示出解决这些挑战的潜力，这些特性可以反映细胞特异性形态。先前的工作已经证明了 dMRS 在捕捉脂多糖（LPS）挑战和严重神经疾病中微胶质反应方面的效用，这些反应表现为微胶质代谢物扩散特性的变化。然而，在没有明显神经病理学的人群中，这种 dMRS 指标在检测更微妙和更细微的神经炎症水平方面的能力程度尚不清楚。在这里，我们研究了内在的、源自肠道的全身 LPS 水平与两个大脑区域（丘脑和放射冠）中基于 dMRS 的胆碱、肌酸和 N-乙酰天冬氨酸（NAA）的表观扩散系数（ADC）之间的关系。较高的血浆 LPS 浓度与丘脑区域中胆碱和 NAA 的 ADC 增加显著相关，而在任何被检查的代谢物中，放射冠都没有观察到这种关系。因此，dMRS 可能具有在具有高度可变神经炎症水平的人群中测量微胶质反应的敏感性，并在研究和临床环境中具有广泛应用的潜力。
