Abstract
Lipopolysaccharides (LPS), which are components of the cell wall of Gram-negative bacteria, are among the important factors that induce inflammation, including pulpitis. Autophagy in human dental pulp cells (hDPCs) acts as a protective mechanism that promotes cell survival under adverse conditions through different signaling pathways. In this study, we examined whether LPS increases autophagy in hDPCs and investigated the role of mitogen-activated protein kinases signaling and nuclear factor κB (NF-κB) in this process. We found that stimulation of hDPCs with 0.1 µg/mL LPS increased the protein and mRNA levels of autophagy markers, beclin1 and microtubule associated protein light chain 3II (LC3II). In addition, acridine orange staining and transmission electron microscopy demonstrated the induction of autophagy upon the treatment of LPS. Furthermore, LPS affected phosphorylation of p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK), and the nuclear translocation of NF-κB. While p38 inhibitor suppressed the LPS-induced increase in protein levels of beclin1 and LC3-II. Our results suggest that LPS induced autophagy in hDPCs and affected the phosphorylation of p38, ERK, and JNK, as well as the nuclear translocation of NF-κB. Phosphorylation of p38 may be involved in LPS-induced autophagy in hDPCs.
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Acknowledgements
This study was financially supported by the National Nature Science Foundation of China (No. 81700957, No. 81870750), the Natural Science Foundation of Guangdong province (No. 2016A030310197). The funding bodies had no role in the design, collection, analysis, interpretation of data, or writing of manuscript.
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10735_2021_10004_MOESM1_ESM.tif
Supplementary material 1 Effectsof LPS and p38 inhibitor on autophagic vacuoles in hDPCs. (A) Controlgroup shows fewer autolysosomes (×30000). (B) hDPCs stimulated with 0.1 μg/mLLPS for 12 hours contain more autolysosomes in the cytoplasm (×30000). (C)hDPCs pretreated with SB203580 before stimulation with 0.1 μg/mL LPS for 12hours contain fewer autolysosomes (×30000). Autophagic vacuoles aremarked by red arrows (tif 6099.9 kb)
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Huang, Y., Li, X., Liu, Y. et al. LPS-induced autophagy in human dental pulp cells is associated with p38. J Mol Histol 52, 919–928 (2021). https://doi.org/10.1007/s10735-021-10004-2
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DOI: https://doi.org/10.1007/s10735-021-10004-2