ABSTRACT
Programmed cell death protein 1 (PD-1) is an immune checkpoint modulator and a major target of immunotherapy as anti-PD-1 monoclonal antibodies have demonstrated remarkable efficacy in cancer treatment. Accumulating evidence suggests an important role of PD-1 in the central nervous system (CNS). PD-1 has been implicated in CNS disorders such as brain tumors, Alzheimer’s disease, ischemic stroke, spinal cord injury, multiple sclerosis, cognitive function, and pain. PD-1 signaling suppresses the CNS immune response via resident microglia and infiltrating peripheral immune cells. Notably, PD-1 is also widely expressed in neurons and suppresses neuronal activity via downstream Src homology 2 domain-containing protein tyrosine phosphatase 1 and modulation of ion channel function. An improved understanding of PD-1 signaling in the cross-talk between glial cells, neurons, and peripheral immune cells in the CNS will shed light on immunomodulation, neuromodulation, and novel strategies for treating brain diseases.
ABSTRACT
Stroke is one of the major causes of death and disability in China and even worldwide.At present, treatment of stroke has been traditionally focused on reducing death of ischemic cells.However,clinical trials have shown that none of neuroprotective drugs tested achieve clinical benefit after acute stroke.Exosomes are 30~100 nm extracellular vesicles derived from cells with cell membrane structure.Many studies suggest exosomes play essential roles in intercellular communication by transferring their cargo between source and target cells in brain.Emerging data show that exsomes also make a contribution to brain recovery via regulating highly interactive process pathway after stroke.Here,we review these advances and highlight the potential therapeutic functions of exosomes in brain remodeling after stroke.