Hematopoietic progenitor cells specifically induce a unique immune response in dental pulp under conditions of systemic inflammation

Abstract

Teeth are exposed to various stimuli, including bacterial, thermal, and physical stimuli. Therefore, immune cells present in the normal dental pulp and the immune response to these stimuli have been studied. However, the relationship between systemic inflammation, such as that induced by viral infection, and changes occurring in dental pulp is not well known. This study aimed to investigate the immunological and hematological responses to systemic inflammation in dental pulp. Poly(I:C), a toll-like receptor 3 agonist, was injected into mice every two days to simulate a systemic inflammatory state in which type I interferon (IFN-I) was produced. The untreated normal state was defined as a steady state, and the states of acute and chronic inflammation were defined according to the period of administration. Changes in the abundance and dynamics of hematopoietic and immune cells in dental pulp, bone marrow and peripheral blood were quantitatively investigated in the steady state and under conditions of inflammation induced by IFN-l. We found that dental pulp in the steady state contained only a few hematopoietic cells, but a greater variety of immune cells than previously reported. B cells were also found in the steady state. An increase in multipotent progenitor cell levels was observed in the dental pulp during both acute and chronic inflammation. The increased multipotent progenitor cells in the dental pulp during acute inflammation tended to differentiate into the myeloid lineage. On the other hand, there was an influx of B cells into the dental pulp during chronic inflammation. These results revealed that a unique immune response is induced in the dental pulp by systemic inflammation, which would lead to a significant change in the perspective of dentists on the utility of dental pulp in the management of systemic diseases.

Identification of the characteristics of infiltrating immune cells in pulpitis and its potential molecular regulation mechanism by bioinformatics method

“…The dental pulp is a complex tissue composed of many types of cells, and its dentin-pulp complex acts as a barrier, in which odontoblasts and immune cells are strategically distributed to prevent the invasion of pathogens. There were significant differences in the distribution of odontoblasts, macrophages, and neutrophils and morphological changes between the irreversible pulpitis and the healthy control [ 5 , 6 ]. Dental pulp tissue produces proinflammatory cytokines and chemokines upon recognition of pathogens, including chemokine (C–C motif) ligand 2 (CCL2), CCL5, CCL7, chemokine (C-X-C motif) ligand 8 (CXCL 8), and CXCL10, which regulate immune cell recruitment and activation to coordinate immune responses [ 4 , 7 ].…”