Nrlc5 Deficiency Delayed Bone Healing & Inhibited Osteogenic Differentiation

The role of NLRC5 in bone regeneration is still unknown, this study explored the effect of NLRC5 knockout on osteogenic differentiation of mBMSCs and provided a better understanding of its underlying mechanism. To investigate NLRC5′s role in bone repair, a cortical bone defect model in NLRC5-knockout (KO) mice was utilized, and the mineralization capacity of murine bone marrow-derived stem cells (mBMSCs) was investigated. Results unveiled delayed bone healing and compromised intramembranous ossification in NLRC5-KO mice. Furthermore, NLRC5 deficiency hindered the osteogenic differentiation of mBMSCs, leading to decreased expression of osteogenic genes, PI3K and β-catenin. When NLRC5 expression was rescued in NLRC5-KO mBMSCs, their osteogenic differentiation ability was regained, and the PI3K/AKT signaling pathway was activated. While this pathway was blocked, the expression of β-catenin and the mineralization of mBMSCs decreased. Notably, absence of NLRC5 inhibited CD4+ T cells from differentiating into Treg cell and reduced anti-inflammatory cytokines. BMSCs incubated with supernatant from NLRC5-KO Treg cells exhibited lower osteogenic differentiation than those exposed to supernatant from wild-type Treg cells. These findings suggested that NLRC5 regulated BMSC osteogenic differentiation via the PI3K/AKT/β-catenin signaling pathways and by influencing the immune microenvironment through regulating CD 4+ T cell differentiation. This study underscored NLRC5′s dual role as an immunoregulatory molecule and a key regulator in bone regeneration. The elucidation of the immune-mediated mechanisms of bone metabolism highlights NLRC5 as a promising target for future clinical interventions in bone regeneration.