ACE2 dysregulation and lipid metabolism: Mechanistic interplay between COVID-19 and neurodegeneration

Angiotensin-converting enzyme 2 (ACE2) is the primary cellular receptor of SARS-CoV-2. It is a key regulator of the renin-angiotensin system (RAS) and modulates blood pressure and inflammatory pathways. ACE2 converts pro-inflammatory angiotensin II into the vasoprotective peptide, angiotensin (1-7). This is strongly influenced by the lipid composition of the plasma membrane. Cholesterol-rich lipid rafts play an important role in determining receptor localisation and viral accessibility. Dyslipidaemia, which is common in obesity, diabetes, and metabolic syndrome, has been associated with an increased susceptibility to severe COVID-19 and may amplify systemic inflammation. Aberrant lipid metabolism also contributes to neurodegenerative disorders, including Alzheimer's and Parkinson's diseases, which drive neuroinflammation, synaptic dysfunction, and blood-brain barrier impairment. Notably, similar disturbances and systemic inflammation are increasingly recognised in patients with Long COVID, suggesting overlapping mechanisms that may exacerbate or accelerate neurodegenerative processes. This review explores the interplay between ACE2 regulation, lipid metabolism, and systemic inflammation in COVID-19, with a particular focus on their implications for neurological health. Uniquely, we highlighted the intersection of ACE2 and lipid-related alterations in patients with Long COVID and their potential contribution to the progression of neurodegenerative diseases. In addition, we reviewed therapeutic strategies targeting ACE2, including recombinant soluble ACE2, ACE2-based nanotherapeutics, and lipid-focused interventions, aimed at mitigating acute infection, systemic inflammation, and persistent neurological sequelae. Understanding these mechanisms is essential to prevent long-term neurological consequences of the COVID-19 pandemic.