CRLF1/CLCF1 heterodimer involvement in intervertebral disc degeneration via exacerbation of extracellular matrix degradation and nucleus pulposus cell senescence

Objective

Low back pain (LBP) is one of the most prevalent musculoskeletal disorders and has a significant global impact. Intervertebral disc degeneration (IVDD) is an important cause of LBP. The aim of this study was to test a hypothesis that elucidates the potential role and molecular mechanisms of cytokine receptor-like factor 1 (CRLF1) in IVDD and LBP.

Methods

We identified dysregulated genes in normal and degenerative discs via microarray profiles. We verified the correlation between CRLF1 and the progression of IVDD in animal models and cellular models and further explored the effect of increased CRLF1 on nucleus pulposus cells (NPCs) and its mechanism by RNA-seq. Finally, the ameliorative effect of CRLF1 knockdown on degenerated NPCs was elucidated by in vivo and in vitro experiments.

Results

We verified the close relationship between senescent NPCs and IVDD. We determined that elevated CRLF1 is associated with the progression of NPC senescence and IVDD in animal and cellular models. In addition, fluorescence colocalization and coimmunoprecipitation analysis revealed that CRLF1 forms a heterodimer with cardiac dystrophin-like cytokine 1 (CLCF1), which together activate JAK/STAT3 signaling. This activation enhances the production of senescence-associated secretory phenotype (SASPs) and accelerates NPC senescence. In vitro studies have shown that targeting CRLF1 reduces extracellular matrix (ECM) degradation and alleviates NPC senescence. Correspondingly, in vivo and pain-behavior tests showed that CRLF1 knockdown reduces IVDD and LBP.

Conclusion

The CRLF1/CLCF1 heterodimer is involved in IVDD, and CRLF1 may be an effective therapeutic target for treating IVDD progression and associated LBP.