Immunomodulatory effect of IL‐1RA in LPS‐activated macrophage/dental pulp stem cells co‐culture

Abstract Aims Lipopolysaccharides (LPS)‐activated human dental pulp stem cells (hDPSCs) and macrophage co‐cultures showed downregulated TNF‐α secretion that is modulated by hDPSCs through IDO axis, whereas the secretory levels of IL‐1β remained unchanged. Therefore, sustained production of IL‐1β could contribute to progressive dental pulp inflammation. However, the role of interleukin‐1 receptor antagonist (IL‐1RA) in downregulating the secretion of IL‐1β and TNF‐α in LPS‐activated M0/M1/M2 macrophage and hDPSCs co‐culture has not been studied yet. Therefore, the aim of the present study was to determine the immunomodulatory role of blocking IL‐1 receptors in DPSCs macrophage co‐culture activated with LPS. Methodology Human monocytic cell line THP‐1 was polarized to M0, M1 and M2 macrophages and co‐cultured with hDPSCs. The viability of the co‐cultured cells was assessed by apoptosis assay. Co‐cultures were activated with LPS followed by the assessment of gene expression and protein levels of IL‐1β and TNF‐α with and without IL‐1RA blocking via qRT‐PCR and cytokine flex assay by flow cytometry. Data from three separate experiments were analysed using one‐way anova followed by Tukey's post hoc test and a p ‐value of <.05 was considered statistically significant. Results THP‐1‐derived M0, M1 and M2 macrophages co‐cultured with hDPSCs showed spindle and round‐shaped cells, with >90% viability when assessed by apoptosis assay. Inflammatory TNF‐α and IL‐1β profiles in stimulated co‐cultures showed upregulated IL‐1β, whereas TNF‐α was downregulated ( p < .05). Anti‐inflammatory gene expression levels of IL‐10 and TGF‐β were downregulated ( p < .05). Blocking with IL‐1RA resulted in a remarkable decrease in IL‐1β at the gene expression and protein production levels whilst TNF‐α levels remained low ( p < .05). Levels of anti‐inflammatory cytokine IL‐10 showed no significant difference. Conclusion Blocking the IL‐1 receptor in hDPSCs and macrophage (M0, M1, M2) co‐cultures activated with LPS resulted in downregulation of inflammatory cytokines IL‐1β and TNF‐α. These findings highlight the immunomodulatory effect of IL‐1RA in inflammatory conditions of dental pulp infections.