2006;203:619C631. 4 mice per group; p 0.05. NIHMS600995-supplement-Supp_Figure_S1.tif (6.4M) GUID:?AD96605B-54F3-4237-A93F-519349B48C70 Abstract Transplantation of major histocompatibility complex (MHC)-mismatched mouse neural precursor cells (NPCs) into mice persistently infected with the neurotropic JHM strain of mouse hepatitis virus (JHMV) results in rapid rejection that is mediated, in Ticagrelor (AZD6140) part, by T cells. However, the contribution of the innate immune response to allograft rejection in a model of viral-induced neurological disease has not been well defined. Herein, we demonstrate that the natural killer (NK) cell-expressing activating receptor NKG2D participates in transplanted allogeneic NPC rejection in mice persistently infected with JHMV. Cultured NPCs derived from C57BL/6 (H-2b) mice express the NKG2D ligand retinoic acid early precursor transcript (RAE)-1 but expression was dramatically reduced upon differentiation into either glia or neurons. RAE-1+ NPCs were susceptible to NK cell-mediated killing whereas RAE-1- cells were resistant to lysis. Transplantation of C57BL/6-derived NPCs into JHMV-infected BALB/c (H-2d) mice resulted in infiltration of NKG2D+CD49b+ NK cells and treatment with blocking antibody specific for NKG2D increased survival of allogeneic NPCs. Further, transplantation Ticagrelor (AZD6140) of differentiated RAE-1- allogeneic NPCs into JHMV-infected BALB/c mice resulted in enhanced survival, highlighting a role for the NKG2D:RAE-1 signaling axis in allograft rejection. We also demonstrate that transplantation of allogeneic NPCs into JHMV-infected mice resulted in infection of the transplanted cells suggesting that these cells may be targets for infection. Viral infection of cultured cells increased RAE-1 expression, resulting in enhanced NK cell-mediated killing through NKG2D recognition. Collectively, these results show that in a viral-induced demyelination model, NK cells contribute to rejection of allogeneic NPCs through an NKG2D signaling pathway. Introduction Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) involving immune responses directed against self-antigens within the CNS resulting in neuroinflammation and demyelination1, 2. Ultimately, myelin and axonal loss culminates in extensive disability through defects in neurological function3-6. Although myelin repair can occur during the course of the disease, it is often transient and not sustained7, 8. Therefore, an important unmet clinical need for MS patients is an effective method to induce sustained remyelination while limiting disease progression and ongoing demyelination 9, 10. In recent years, considerable effort has focused on cell replacement therapies through use of neural precursor cells (NPCs) to promote remyelination. Indeed, in animal models of autoimmune neuroinflammatory demyelination there is evidence that transplantation of NPCs results in improved clinical outcome accompanied by reduced neuroinflammation and myelin repair11-15. Using a viral model of demyelination, we have demonstrated that intraspinal transplantation of mouse NPCs into animals with established demyelination results in improved motor skills along with limited spread of demyelination accompanied by axonal sparing and remyelination16. Intracranial infection with the neuroadapted JHM strain of mouse hepatitis virus (JHMV) results in an acute encephalomyelitis followed by chronic immune-mediated demyelinating disease similar clinically and histologically to the human demyelinating disease multiple sclerosis (MS)17-19. While the etiology of MS is unknown, both genetic factors as well as environmental influences (viral infection) have long been considered important in triggering disease20-23. Therefore, defining mechanisms contributing to demyelination as well as remyelination in animals in which disease is initiated by a persistent infection with a neurotropic virus is clinically relevant. With this in mind, we have shown that following intraspinal Ticagrelor (AZD6140) injection of syngeneic NPCs into JHMV-infected mice, transplanted cells are well-tolerated, preferentially differentiate into cells of an oligodendrocyte lineage, and selectively colonize areas of white matter damage within the spinal cord16, 24. While the findings from our transplantation studies emphasize the therapeutic potential of NPCs in ameliorating disease in JHMV-infected mice, the majority of transplantation studies have utilized syngeneic NPCs for CNS engraftment and do not address the important issue of whether MHC-mismatched NPCs are recognized as foreign by the host immune system and subsequently rejected. Evidence argues that unmatched grafts are well-tolerated within the CNS due to muted immunogenicity of NPCs and clinical studies support Rabbit Polyclonal to PEA-15 (phospho-Ser104) that transplantation of allogeneic NPCs results in prolonged survival25-27. However, the immunoprivileged status of NPCs has recently been questioned28 and more recent studies argue that allogeneic NPCs exhibit diminished survival upon transplantation29-31. Our recent studies demonstrate that transplantation.