Injury-transduced SerpinOLs modulate neuroinflammation and glial activation in the diseased and non-diseased CNS

Oligodendroglial dysfunction is common in CNS diseases and injuries, but the molecular and functional responses of oligodendroglia to CNS pathologies remain poorly defined. Here, we report that oligodendrocytes (OLs) respond to demyelinating diseases by dysregulating serine protease inhibitor clade A member 3N (SERPINA3N). Homeostatic OLs transition to Serpina3n-expressing OLs (SerpinOLs) under other diseased conditions including stroke, endotoxicity, neurodegeneration, neurotrauma, and non-diseased healthy aging conditions. Mechanistically, general neuroinflammation or inflammatory mediators is insufficient for SerpinOL transition. Instead, oligodendrocyte damage/injury, even in the absence of neuroinflammation or glial activation, is sufficient for the transition. Phenotypically, SerpinOLs are characterized by molecular signatures of inflammatory and immune regulation and STAT3 signaling activation. Functionally, SerpinOLs exacerbate neuroinflammation and promote glial activation toward pro-inflammatory and neurodegenerative states. Together, our findings suggest SerpinOLs are a common population of injury-transduced OLs that amplify neuroinflammation and glial activation in the diseased and non-diseased CNS through SERPINA3N secretion. Our findings provide new insights into myelination-independent role of OLs in regulating CNS pathophysiology.