PRDX1-TLR4-p65 axis inhibits RANKL-mediated osteoclast differentiation

Peroxiredoxin 1 (PRDX1), traditionally known as an intracellular antioxidant enzyme, has emerged as a regulator of inflammatory responses via Toll-like receptor 4 (TLR4) signaling. Despite this, the mechanistic details of the PRDX1-TLR4 axis and its impact on osteoclast differentiation remain elusive. Here, we show that PRDX1 suppresses RANKL-induced osteoclast differentiation. Utilizing pharmacological inhibitors, we reveal that PRDX1 inhibits osteoclastogenesis through both TLR4/TRIF and TLR4/MyD88 pathways. Transcriptome analysis revealed PRDX1-mediated alterations in gene expression, particularly upregulating serum amyloid A3 (SAA3) and aconitate decarboxylase 1 (ACOD1), known inhibitors of osteoclast differentiation. Mechanistically, PRDX1-TLR4 signaling activates p65, promoting SAA3 and ACOD1 expression while inhibiting NFATc1, a master regulator of osteoclastogenesis. Remarkably, PRDX1 redirects p65 binding from NFATc1 to SAA3/ACOD1 promoters, thereby suppressing osteoclast formation. Structural analysis showed that monomeric variants of PRDX1 with enhanced TLR4 binding exhibit potent inhibition of osteoclast differentiation. Our findings elucidate the inhibitory role of PRDX1-TLR4 axis in osteoclastogenesis, providing insights into therapeutic strategies for bone-related disorders. To explore the impact of PRDX1 on osteoclast differentiation, bone marrow macrophages (BMMs) were exposed to RANKL (100ng/ml) for 48 hours, with or without the presence of PRDX1.