The relationship between increased levels of microbiota-derived lipopolysaccharide in obesity and the pathophysiology of neurodegenerative diseases

Abstract

Lipopolysaccharide (LPS), a potent pro-inflammatory endotoxin derived from the outer membrane of Gram-negative bacteria, has been identified as a crucial link between obesity-related systemic inflammation and the onset of neurodegenerative diseases. Modifications in gut microbiota associated with obesity disrupt the integrity of the intestinal barrier, resulting in increased permeability and heightened levels of circulating LPS a phenomenon known as metabolic endotoxemia. The elevated presence of LPS promotes persistent low-grade inflammation and oxidative stress, both of which are critical contributors to neurodegeneration. This review aims to explore the biological pathways through which LPS influences the development and advancement of neurodegenerative diseases, including Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS). The role of LPS in exacerbating neuroinflammation through the activation of microglia and the impairment of the blood-brain barrier (BBB) is thoroughly examined. Moreover, the review delves into the interrelated effects of obesity-related systemic inflammation, insulin resistance, and mitochondrial dysfunction in enhancing LPS-driven neurodegenerative mechanisms. Special emphasis is placed on the common pathological characteristics present in these disorders, such as protein misfolding, neuronal apoptosis, and disrupted synaptic function, which may be exacerbated by LPS-related processes. By clarifying the relationships between obesity, LPS, and neurodegenerative diseases, this review underscores potential therapeutic approaches aimed at modulating gut microbiota, improving intestinal barrier function, and mitigating systemic inflammation to prevent or decelerate the progression of these debilitating disorders.

Keywords: Adipose tissue; Blood-brain barrier; Gut microbiota; Lipopolysaccharide; Metabolic endotoxemia; Neurodegenerative diseases; Neuroinflammation; Obesity.