Introduction: Inflammation of the dental pulp due to caries is a highly prevalent pathology which causes intense pain. Here, we sought to correlate the clinical picture with the histopathology of the affected tissue. The interaction between nociceptive neurons and immune cells is fundamental to regulate the inflammatory response, but little is known about the glial network involved in this process, and its impact on caries pathogenesis.
Methods: This study characterized Schwann cells and other neuroimmune components in human dental pulps with reversible and symptomatic irreversible pulpitis (IP). Twenty eight human teeth were extracted for reasons beyond the scope of this study. Twelve were diagnosed as reversible and symptomatic IP respectively, and 4 as controls. The teeth were decalcified, processed for immunolabeling and analyzed with confocal microscopy.
Results: Symptomatic IP was characterized by a significantly higher density of neutrophils, and the release of neutrophil extracellular traps. Between IP and healthy controls, there were significant differences in the density of Schwann cells, macrophages, and neutrophils, in addition to morphological alterations. In IP, Schwann cell arborization extended toward the pulpodentinal interface along with more spindle-shaped cell bodies, while some macrophages displayed a distinct fusiform phenotype.
Conclusions: The dental pulp has a complex multicellular organization and its pulpodentinal interface acts as a barrier in which Schwann and immune cells are distributed strategically to stop the progress of pathogens. A synergistic interaction of Schwann cells with immune cells creates a novel perspective to better understand the role of these glial cells and their active participation in pulpal inflammation.
Keywords: Caries; Schwann cell; dental pulp; macrophage; neutrophil; pulpitis.
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