The anti-fibrotic effects of RLN3 aggravated the pathogenesis of adolescent idiopathic scoliosis-a preliminary study

Previous research proposed that ligament laxity is a clinical feature that can be easily overlooked in patients with adolescent idiopathic scoliosis (AIS). Relaxin and relaxin-related peptides, which have anti-fibrosis roles in the vascular and kidney system and relax the pubic symphysis during pregnancy, may contribute to ligament laxity. The goal of this research was to evaluate the role of in AIS. We found significantly increased relaxin-3 plasma in patients with AIS, as well as a significant correlation between joint hypermobility and relaxin 3 plasma levels. In a classic mouse model (C57BL/6J) of scoliosis, which was established according to the literature, showed significantly higher relaxin-3 plasma levels compared to normal group. In the relaxin-3 knockout C57BL/6J mice model the prevalence of scoliosis was significantly decreased. An in vitro experiment showed that relaxin 3 has anti-fibrotic effects on spinal ligament fibroblasts in both humans and mice by inhibiting TGF-{beta} via relaxin family peptide receptor 3 (RXFP3) and increasing expression of matrix metalloproteinase 2 and matrix metalloproteinase 9 via the TGF-{beta}/Smad2 and MAPK-ERK1/2 pathway. Blocking RXFP3 function with R3(B1-22)R significantly decreased the prevalence of scoliosis in C57BL/6J mice. In summary, the anti-fibrotic effects of relaxin-3 and RXFP3 activation may aggravate the pathogenesis of AIS.