Melatonin exerts anti-fibrinolytic effects by regulating IL-1β-induced changes in uPA, uPAR, and PAI-1 expression/production in human dental pulp cells
Mei-Chi Changa,b, Bor-Hao Zhongc,d,1, Hui-Na Leee,f, Fu-Hsiung Chuange,f, Ming-Shu Leec,d, Hsiao-Hua Changc,d, Yu-Hwa Panb,*, and Jiiang-Huei Jengc,d,e,f,**
a Biomedical Science Team, Chang Gung University of Science and Technology, Kwei-Shan, Taoyuan City, Taiwan
b Department of Dentistry, Chang Gung Memorial Hospital, Taipei, Taiwan
c School of Dentistry, National Taiwan University Medical College, Taipei, Taiwan
d Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan
e School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
f Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
1 Bor-Hao Zhong contributed equally to the 1st author
Interleukin-1b (IL-1β) is a pro-inflammatory cytokine and its expression is increased in inflamed dental pulp. IL-1β affects plasminogen activation system molecules, which are crucial for tissue inflammation, fibrinolysis, matrix turnover, and cell adhesion and migration. Melatonin, which provides circadian and seasonal signals, is a physiological endocrine generated by the pineal gland. It has anti-oxidant and anti-inflammatory properties. Studies are warranted to determine whether melatonin prevents IL-1β-induced expression/production of plasminogen system molecules. Human dental pulp cells (HDPCs) were exposed to IL-1β or melatonin alone or to IL-1β with/without pretreatment with melatonin or other inhibitors. The mRNA expression of uPA, uPAR, and PAI-1 was quantified using real-time polymerase chain reaction analysis. The cellular uPA, PAI-1, and soluble uPAR (suPAR) production was determined using an enzyme-linked immunosorbent assay. Signaling molecules’ protein expression was analyzed by immunofluorescent staining. We found that IL-1β (0.1–10 ng/mL) stimulated uPA and uPAR expression/production but inhibited PAI-1 expression/production of HDPCs. Melatonin inhibited uPA but stimulated uPAR/suPAR and PAI-1 expression/production. Intriguingly, melatonin prevented IL-1β-induced uPA mRNA expression/production. Conversely, melatonin enhanced the IL-1β-induced uPAR and PAI-1 mRNA expression/protein production of HDPCs. IL-1β-induced suPAR production was attenuated by U0126 (a MEK/ERK inhibitor), SB203580 (a p38 inhibitor), and 5Z-7oxozeaenol (a TAK1 inhibitor), whereas SB203580 prevented an IL-1β-induced decline of PAI-1 production. Moreover, melatonin attenuated the IL-1b-induced p-ERK, p-p38, p-Akt and p-TAK1. These results revealed the crucial role of IL-1β in the pathogenesis of pulpal inflammation/repair via stimulation of uPA and uPAR and inhibition of PAI-1, which can be differentially regulated by p38, Akt, MEK/ERK, and TAK1. Melatonin exerts an anti-fibrinolytic effect on IL-1β-induced changes in uPA, uPAR, and PAI-1 in HDPCs. Clinically, the melatonin levels of patients may affect pulpal inflammatory response. Melatonin and signal transduction inhibitors may be administered concomitantly for the prevention and treatment of pulpal inflammatory diseases.
Keywords: Dental pulp; Inflammation; Interleukin-1β; Melatonin; Plasminogen activation system molecules
https://doi.org/10.38212/2224-6614.3415
(https://www.jfda-online.com/journal/vol30/iss3/11)