Orosomucoid 2 is an endogenous regulator of neuronal mitochondrial biogenesis and promotes functional recovery post-stroke

Development of functional recovery therapies is critical to reduce the global impact of stroke as the leading cause of long-term disability. Our previous studies found that acute-phase protein orosomucoid (ORM) could provide an up to 6h therapeutic time window to reduce infarct volume in acute ischemic stroke by improving endothelial function. However, its role in neurons and functional recovery post-stroke remains largely unknown. Here, we showed that exogenous ORM administration with initial injection at 0.5h (early) or 12h (delayed) post-MCAO daily for consecutive 7 days significantly decreased infarct area, improved motor and cognitive functional recovery, and promoted mitochondrial biogenesis after MCAO. While neuron-specific knockout of ORM2, a dominant subtype of ORM in the brain, produced opposite effects which could be rescued by exogenous ORM. In vitro, exogenous ORM protected SH-SY5Y cells from OGD-induced damage and promoted mitochondrial biogenesis, while endogenous ORM2 deficiency worsened these processes. Mechanistically, inactivation of CCR5 or AMPK eliminated the protective effects of ORM on neuronal damage and mitochondrial biogenesis. Taken together, our findings demonstrate that ORM, mainly ORM2, is an endogenous regulator of neuronal mitochondrial biogenesis by activating CCR5/AMPK signaling pathway, and might act as a potential therapeutic target for the functional recovery post-stroke.