A multidimensional immunological perspective on long COVID.

Long COVID is a chronic condition that arises after SARS-CoV-2 infection and is characterized by persistent and often debilitating symptoms, such as fatigue, cognitive dysfunction ("brain fog"), dyspnea, and autonomic disturbances. Increasing evidence suggests that Long COVID shares key immunopathological mechanisms with autoimmune diseases, primarily sustained immune dysregulation. In individuals with genetic or immunological susceptibility, SARS-CoV-2 infection can trigger the production of autoantibodies targeting cytokines, membrane receptors, and components of the autonomic nervous system (ANS), thereby disrupting neuroimmune homeostasis. This immune imbalance may impair anti-inflammatory regulatory pathways, such as the cholinergic anti-inflammatory pathway (CAP), and may contribute to a chronic state of inflammation and autoimmunity. One proposed contributor to this process is inflammaging - a chronic, low-grade inflammation associated with aging - which may not only predispose individuals to Long COVID but may also be amplified by the persistent immune activation seen in this condition. In this perspective, we propose a conceptual framework in which inflammaging, immune-tolerance breakdown, and autonomic dysfunctions interact to sustain the pathophysiology of Long COVID. We discuss emerging biomarkers across these axes, including inflammatory cytokines, circulating autoantibodies, immune cell phenotypes, epigenetic modifications, and heart rate variability. Advances in inflammaging-related biomarkers and biological clocks may support early identification of individuals at higher risk for persistent immune and autonomic dysregulation, ultimately informing more precise diagnostic and therapeutic strategies for Long COVID.