The checkpoint inhibitor PD-1H/VISTA controls osteoclast-mediated multiple myeloma bone disease
Jing Fu, Shirong Li, Huihui Ma, Jun Yang, Gabriel M. Pagnotti, Lewis M. Brown, Stephen J. Weiss, Markus Y. Mapara, Suzanne Lentzsch
Abstract
Abstract Multiple myeloma bone disease is characterized by the development of osteolytic bone lesions. Recent work identified matrix metalloproteinase 13 as a myeloma-derived fusogen that induces osteoclast activation independent of its proteolytic activity. We now identify programmed death-1 homolog, PD-1H, as the bona fide MMP-13 receptor on osteoclasts. Silencing PD-1H or using Pd-1h -/ - bone marrow cells abrogates the MMP-13-enhanced osteoclast fusion and bone-resorptive activity. Further, PD-1H interacts with the actin cytoskeleton and plays a necessary role in supporting c-Src activation and sealing zone formation. The critical role of PD-1H in myeloma lytic bone lesions was confirmed using a Pd-1h -/- myeloma bone disease mouse model wherein myeloma cells injected into Pd-1h -/- Rag2 -/- results in attenuated bone destruction. Our findings identify a role of PD-1H in bone biology independent of its known immunoregulatory functions and suggest that targeting the MMP-13/PD-1H axis may represent a potential approach for the treatment of myeloma associated osteolysis.