Aging-associated endo-lysosomal dysfunction drives inflammaging and neurodegeneration through the STING-IFN-I axis
All animals age. However, aging is a heterogeneous process and individual organisms age differently. Moreover, within the same organism, cells or organs do not age at the same time or speed. For instance, although neurodegeneration is a key trait of aging, neurological symptoms normally manifest long after multiple indicators of aging in peripheral tissues. The genetic determinants of aging remain poorly understood. Mutations in leucine-rich repeat kinase 2 (LRRK2) are major genetic risk factors for Parkinsons disease (PD). By analyzing PD patients and mice with LRRK2 gain of function mutation (LRRK2GoF), we demonstrate that PD is an accelerated aging disease characterized by systemic low-grade STING-dependent inflammation (inflammaging) that first manifests in the periphery then disrupts the blood brain barrier and progresses to the brain resulting in neurodegeneration. Mechanistically, we demonstrate that a primary consequence of aging or Lrrk2GoF is endolysosomal decline. This results in the cytosolic build-up of extraneous self-DNA and subsequent shedding of DNA-containing extracellular vesicles thereby triggering the cGAS- STING pathway cell-intrinsically and intercellularly in distant host cells. This study unveils the cGAS-STING pathway and LRRK2GoF as key determinants and potential targets for preventive or therapeutic strategies against accelerated aging, inflammaging and neurodegeneration.