Single-cell transcriptome profiling identifies the activation of type I interferon signaling in ossified posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) is a condition comprising ectopic bone formation from spinal ligaments. This disease is a leading cause of myelopathy in the Asian population. However, the molecular mechanism underlying OPLL and efficient preventive interventions remain unclear. Here, we performed single-cell RNA sequencing and revealed that type I interferon (IFN) signaling was activated in the ossified ligament of patients with OPLL. We also observed that IFN-beta stimulation promoted the osteogenic differentiation of preosteoblasts in vitro and activated the ossification-related gene SPP1, thereby confirming the single-cell RNA sequencing findings. Further, blocking the IFN-alpha/beta subunit 1 receptor (IFNAR1) using an anti-IFNAR1 neutralizing antibody markedly suppressed osteogenic differentiation. Together, these results demonstrated that the type I IFN signaling pathway facilitated ligament ossification, and the blockade of this signaling might provide a foundation for the prevention of OPLL.