diABZI and poly(I:C) inhibit osteoclastic bone resorption by inducing IRF7 and IFIT3

Type I interferons (IFN-I) are pleiotropic factors endowed with multiple activities that play important roles in innate and adaptive immunity. Although many studies indicate that IFN-I inducers exert favorable effects on broad-spectrum antivirus, immunomodulation, and anti-tumor activities by inducing endogenous IFN-I and IFN-stimulated genes, their function in bone homeostasis still needs further exploration. Here, our study demonstrates 2 distinct IFN-I inducers, diABZI and poly(I:C), as potential therapeutics to alleviate osteolysis and osteoporosis. First, IFN-I inducers suppress the genes that control osteoclast (OC) differentiation and activity in vitro. Moreover, diABZI alleviates bone loss in Ti particle-induced osteolysis and ovariectomized -induced osteoporosis in vivo by inhibiting OC differentiation and function. In addition, the inhibitory effects of IFN-I inducers on OC differentiation are not observed in macrophages derived from Ifnar1-/-mice, which indicate that the suppressive effect of IFN-I inducers on OC is IFNAR-dependent. Mechanistically, RNAi-mediated silencing of IRF7 and IFIT3 in OC precursors impairs the suppressive effect of the IFN-I inducers on OC differentiation. Taken together, these results demonstrate that IFN-I inducers play a protective role in bone turnover by limiting osteoclastogenesis and bone resorption through the induction of OC-specific mediators via the IFN-I signaling pathway.