Thymosin α1 alleviates pulpitis by inhibiting ferroptosis of dental pulp cells.
This study investigated the role of ferroptosis (a form of iron-dependent regulated cell death) in pulpitis and evaluated whether thymosin α1 (Tα1) could mitigate this process. Using single-cell RNA sequencing (scRNA-seq) of tissue from 3 pulpitis and 3 healthy pulp samples, researchers identified 12 distinct cell clusters and found that differentially expressed ferroptosis-related genes (DE-FRGs) were broadly present across clusters in pulpitis tissue. Elevated reactive oxygen species (ROS) and Fe²⁺ levels, alongside reduced GPX4 and elevated PTGS2 expression by immunohistochemistry, suggested active ferroptosis in inflamed pulp. In LPS-stimulated dental pulp cells (DPCs) in vitro, Tα1 treatment was associated with increased GPX4 and FTL expression and reduced inflammatory markers (TNF-α, IL-1β, IL-6) and Fe²⁺ levels. In rat pulpitis models, delivery of prothymosin α (PTMA, the Tα1 precursor) via gelatin sponge or direct injection reduced inflammatory cell infiltration, decreased PTGS2, and increased GPX4. RNA sequencing of LPS-stimulated DPCs confirmed reversal of DE-FRG expression with Tα1 treatment. Key limitations include small human tissue sample sizes (n=3 per group), reliance on animal and cell models for intervention data, and the lack of human clinical trials.
Why this grade: Although human tissue was used for sequencing/profiling (n=3 per group), all intervention and mechanistic experiments were conducted in vitro (cell models) and in rats, providing no controlled evidence of efficacy in human patients.
Tooth pulpitis is a prevalent oral disorder. Understanding the underlying mechanisms of pulpitis and developing effective treatment strategies hold great significance. Ferroptosis has recently emerged as a new form of cell death, but the role of ferroptosis in pulpitis remains largely unknown. In our study, single-cell RNA sequencing (scRNA-seq) was used to identify cellular heterogeneity between 3 pulpitis tissue and 3 healthy pulp tissue, and explored ferroptosis occurrence in pulpitis tissue and inflamed dental pulp cells (DPCs). In scRNA-seq, 40 231 cells (Pulpitis: 17 814; Healthy pulp: 22 417) were captured, and visualized into 12 distinct cell clusters. Differentially expressed ferroptosis-related genes (DE-FRGs) were almost presented in each cluster in pulpitis vs healthy pulp. ROS and Fe 2+ levels significantly rose, and immunohistochemistry showed low expression of GPX4 and high expression of PTGS2 in pulpitis. In LPS-stimulated DPCs, thymosin α1 increased the expression of GPX4 and FTL, and decreased expression of TNF-α, IL-1β, IL-6, and Fe 2+ levels. In rat pulpitis models, both prothymosin α (PTMA, precursor of thymosin α1) gelatin sponge placed at the hole of pulp (LPS-P(gs)) and PTMA injection in pulp (LPS-P(i)) significantly reduced infiltration of inflammatory cells and expression of PTGS2, and increased the expression of GPX4. In RNA sequencing, the expression of DE-FRGs were reversed when thymosin α1 were added in LPS-stimulated DPCs. Collectively, single-cell atlas reveals cellular heterogeneity between pulpitis and healthy pulp, and ferroptosis occurrence in pulpitis. Thymosin α1 may reduce ferroptosis in DPCs to alleviate pulpitis and thus potentially has the ability to treat pulpitis.
Educational summary of published research — not medical advice. License: cc by. Full text is shown only where licensing permits.