Neutrophil extracellular traps drive osteoporosis via NCF2-dependent signaling: integrated transcriptomics with mechanistic validation

BACKGROUND: Inflammation and immune responses play key roles in osteoporosis (OP) pathogenesis. Osteoimmunology highlights immune dysregulation as a significant contributor to OP, but the specific biological mechanisms linking immune dysfunction to bone loss remain unclear. Understanding these mechanisms is essential for targeted therapies. METHODS: We established a rat OP model via bilateral ovariectomy. Transcriptomic sequencing (RNA-seq) identified differentially expressed genes (DEGs), and summary data-based Mendelian randomization (SMR) analysis validated their causal associations with OP. Primary neutrophils isolated from bone marrow and differentiated HL-60 neutrophil-like cells were induced to form neutrophil extracellular traps (NETs), and siRNA was employed to knock down the NCF2 gene. Conditioned media from these neutrophils were subsequently applied to primary osteoblasts to evaluate effects on osteogenic differentiation. RESULTS: RNA-seq identified 4,497 DEGs (1,606 upregulated, 2,891 downregulated) in OP rats, significantly enriched in immune response and NETs formation pathways. NETs markers (NE, MPO, CitH3) were markedly elevated in OP bone tissue and stimulated neutrophils. SMR analysis identified VDAC1, PLCG2, and NCF2 as key genes significantly associated with OP risk, experimentally validated at the tissue and cellular levels. Knockdown of NCF2 reduced NETs formation in neutrophil-like cells and alleviated NETs-induced osteoblast differentiation impairment. Drug prediction and molecular docking analyses demonstrated high affinity and pharmacological potential targeting these genes. CONCLUSIONS: This study unveils the link between NETs formation and OP, highlighting NCF2 as crucial players. These findings provide new insights into immune inflammation's role in bone metabolism and pave the way for targeted OP therapies.