RRC ID 78073
Author Kawakami K, Fukuda T, Toyoda M, Nakao Y, Hayashi C, Watanabe Y, Aoki T, Shinjo T, Iwashita M, Yamashita A, Shida M, Sanui T, Uchiumi T, Nishimura F.
Title Luteolin Is a Potential Immunomodulating Natural Compound against Pulpal Inflammation.
Journal Biomed Res Int
Abstract AIM:The present study evaluated the therapeutic effects of luteolin in alleviating pulpitis of dental pulp- (DP-) derived microvesicles (MVs) via the inhibition of protein kinase R- (PKR-) mediated inflammation. Methodology. Proteomic analysis of immortalized human dental pulp (DP-1) cell-derived MVs was performed to identify PKR-associated molecules. The effect of luteolin on PKR phosphorylation in DP-1 cells and the expression of tumor necrosis factor-α (TNF-α) in THP-1 macrophage-like cells were validated. The effect of luteolin on cell proliferation was compared with that of chemical PKR inhibitors (C16 and 2-AP) and the unique commercially available sedative guaiacol-parachlorophenol. In the dog experimental pulpitis model, the pulps were treated with (1) saline, (2) guaiacol-parachlorophenol, and (3) luteolin. Sixteen teeth from four dogs were extracted, and the pulp tissues were analyzed using hematoxylin and eosin staining. Immunohistochemical staining was performed to analyze the expression of phosphorylated PKR (pPKR), myeloperoxidase (MPO), and CD68. Experimental endodontic-periodontal complex lesions were established in mouse molar through a silk ligature and simultaneous MV injection. MVs were prepared from DP-1 cells with or without pretreatment with 2-AP or luteolin. A three-dimensional microcomputed tomography analysis was performed on day 7 (n = 6). Periodontal bone resorption volumes were calculated for each group (nonligated-ligated), and the ratio of bone volume to tissue volume was measured.
RESULTS:Proteomic analysis identified an endogenous PKR activator, and a protein activator of interferon-induced PKR, also known as PACT, was included in MVs. Luteolin inhibited the expressions of pPKR in DP-1 cells and TNF-α in THP-1 cells with the lowest suppression of cell proliferation. In the dog model of experimental pulpitis, luteolin treatment suppressed the expression of pPKR-, MPO-, and CD68-positive cells in pulp tissues, whereas guaiacol-parachlorophenol treatment caused coagulative necrosis and disruption. In a mouse model of endodontic-periodontal complex lesions, luteolin treatment significantly decreased MV-induced alveolar bone resorption.
CONCLUSION:Luteolin is an effective and safe compound that inhibits PKR activation in DP-derived MVs, enabling pulp preservation.
Volume 2024
Pages 8864513
Published 2024-1-1
DOI 10.1155/2024/8864513
PMID 38304347
PMC PMC10834097
MeSH Alveolar Bone Loss* Animals Chlorophenols* Dental Pulp / metabolism Dogs Guaiacol Humans Inflammation / metabolism Luteolin / pharmacology Mice Proteomics Pulpitis* Tumor Necrosis Factor-alpha / pharmacology X-Ray Microtomography
Resource
Human and Animal Cells THP-1(RCB1189) RAW 264(RCB0535)