DPSCs from Inflamed Pulp Modulate Macrophage Function via the TNF-α/IDO Axis

Area of Science:

• Dental Pulp Biology
• Immunology
• Stem Cell Research

Background:

• Human dental pulp stem cells (DPSCs) possess regenerative potential.
• Inflamed DPSCs (I-DPSCs) from carious teeth retain stemness and differentiation capabilities.
• Macrophages are key regulators of pulpal inflammation and repair.

Purpose of the Study:

• To investigate the immunomodulatory effects of DPSCs and I-DPSCs on macrophage functions.
• To elucidate the underlying mechanisms of DPSC/I-DPSC-mediated immunomodulation.
• To assess the role of indoleamine-pyrrole 2,3-dioxygenase (IDO) in this process.

Main Methods:

• Isolation and characterization of DPSCs and I-DPSCs.
• In vitro coculture of DPSCs/I-DPSCs with differentiated THP-1 cells (macrophages).
• Measurement of cytokine secretion (TNF-α, IL-1β) and assessment of IDO and COX-2 pathways.

Main Results:

• DPSCs and I-DPSCs significantly suppressed TNF-α secretion by macrophages.
• This suppression was mediated by the indoleamine-pyrrole 2,3-dioxygenase (IDO) pathway, not COX-2.
• IDO expression was elevated in macrophages and mesenchymal stromal cells within inflamed pulp tissues.

Conclusions:

• I-DPSCs exhibit stem cell properties and immunomodulatory functions similar to DPSCs.
• DPSCs and I-DPSCs suppress macrophage TNF-α production through the IDO axis.
• These findings provide a mechanistic basis for the role of DPSCs in dental pulp innate immunity and repair.