Novel Molecular Insights into the Anti-Inflammatory and Antifibrotic Effects of Dexamethasone on Human Ligamentum Flavum-Derived Cells

Lumbar spinal stenosis (LSS) is caused by multiple degenerative changes including the hypertrophy of the ligamentum flavum (LFH). Inflammation and fibrosis contribute to LFH and glucocorticoid drugs (GCDs) are generally used to manage LSS symptoms. However, a thorough understanding of the molecular mechanisms exerted by GCD in ligamentum flavum (LF) cells remains incomplete. Primary human LF cells were isolated from surgical specimens and stimulated with pro-inflammatory agents (IL-1α, IL-1β, LPS) or the profibrotic cytokine TGFβ1, in the presence or absence of dexamethasone. Gene and protein expression levels of inflammatory, fibrotic, and ossification-related markers were analysed using RT-qPCR and Western blotting. Dexamethasone significantly suppressed the expression of key pro-inflammatory, fibrotic, and ossification markers (IL-6, COX2, COL3A1, MMPs, TNFRSF11b) in both acute and prolonged models of LF inflammation. However, under TGFβ1 stimulation, dexamethasone attenuated inflammatory gene expression but failed to reduce the expression of major fibrosis-associated genes, such as COL3A1, bFGF, and POSTN. Dexamethasone effectively suppresses inflammation-mediated fibrosis in LF-derived cells, indicating its potential to both prevent and reverse LFH progression in the context of LSS. However, its limited efficacy against TGFβ1-driven fibrotic pathways highlights the need for combination therapies targeting both inflammation and fibrosis for more comprehensive management of LFH. These findings support further exploration of corticosteroids as therapeutic agents for hypertrophic ligament disorders.