Blockade of Cyclophilin D Attenuates Oxidative Stress-Induced Cell Death in Human Dental Pulp Cells

Abstract

Pathological stimuli, such as bacterial activity, dental bleaching, and nonpolymerized resin monomers, can cause death of dental pulp cells (DPCs) through oxidative stress- (OS-) induced mitochondrial dysfunction. However, the crucial molecular mechanisms that mediate such a phenomenon remain largely unknown. OS is characterized by the overproduction of reactive oxygen species (ROS), e.g., H2O2, O2−, and ⋅OH. Mitochondria are a major source of ROS and the principal attack target of ROS. Cyclophilin D (CypD), as the only crucial protein for mitochondrial permeability transition pore (mPTP) induction, facilitates the opening of mPTP and causes mitochondrial dysfunction, leading to cell death. In the present study, we hypothesized that CypD-mediated mitochondrial molecular pathways were closely involved in the process of OS-induced death of human DPCs (HDPCs). We tested the phenotypic and molecular changes of HDPCs in a well-established OS model—H2O2 treatment. We showed that H2O2 dramatically reduced the viability and increased the death of HDPCs in a time- and dose-dependent manner by performing MTT, flow cytometry, and TUNEL assays and quantifying the expression changes of Bax and Bcl-2 proteins. H2O2 also induced mitochondrial dysfunction, as reflected by the increased mitochondrial ROS, reduced ATP production, and activation of mPTP (decreased mitochondrial membrane potential and enhanced intracellular Ca2+ level). An antioxidant (N-acetyl-L-cysteine) effectively preserved mitochondrial function and significantly attenuated H2O2-induced cytotoxicity and death. Moreover, H2O2 treatment markedly upregulated the CypD protein level in HDPCs. Notably, genetic or pharmacological blockade of CypD significantly attenuated H2O2-induced mitochondrial dysfunction and cell death. These findings provided novel insights into the role of a CypD-dependent mitochondrial pathway in the H2O2-induced death in HDPCs, indicating that CypD may be a potential therapeutic target to prevent OS-mediated injury in dental pulp.

Curcumin Protects Osteoblasts From Oxidative Stress-Induced Dysfunction via GSK3β-Nrf2 Signaling Pathway

“…The different treating condition of the compounds were as follows: H 2 O 2 (0.1-1 mM, Sigma, United States) for 6 h, Cur (0.25 µM, Sigma, United States) for 24 h, TDZD-8 (5 µM, Sigma, United States) for 1 h, tBHQ (5 µM, Sigma, United States) for 1 h, NAC, the widely used antioxidant for positive control (2.5 mM, Sigma, United States) for 1 h, according to previous studies (Dai et al, 2017;Cuadrado et al, 2018;Huang et al, 2019) and our preliminary data (data not shown). Cells were treated with or without H 2 O 2 and the indicated compounds for various conditions in basic medium or osteogenesis differentiation medium.…”

Can different agents reduce the damage caused by bleaching gel to pulp tissue? A systematic review of basic research

“…Then, 16 studies were excluded, and the reasons for their exclusion can be found in Figure 1 and Supplementary Data 1 [ 32 33 34 35 36 37 38 39 40 41 42 43 44 ]. Twenty-seven studies meeting the inclusion criteria were selected for qualitative analysis [ 1 3 6 11 12 17 23 24 25 26 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 ].…”

“…Table 2 presents data from 19 in vitro studies that explored various agents aimed at reducing cytotoxicity during the bleaching process [ 6 23 24 45 46 47 48 49 50 51 52 53 54 55 56 57 ]. The majority of these studies utilized human dental pulp cells (HDPCs) and mouse dental papilla Cell-23 (MDPC-23) cells, with each cell type being used in 10 studies.…”

Melatonin Protects TEGDMA induced Pre-odontoblasts Mitochondrial Apoptosis via JNK/MAPK Signaling Pathway

“…MtROS is an widely accepted initiator of apoptosis through numerous mechanisms, and it is not only related to damage of mitochondrial function, but also leading to an apoptotic signaling pathway cascade [9] [33] [34] . Notably, as the products of mitochondrial metabolism, mtROS comes from the respiratory chain when mitochondria are functionally disordered [12] .…”

“…Mitochondria play vital roles in many cellular processes including cell proliferation, metabolism and apoptosis [9] [10] [11] . Accumulating evidence has implicated excess reactive oxygen species (ROS) in mitochondria promote caspase-dependent apoptosis, so mitochondria are identi ed as the center of apoptosis through the intrinsic pathway [12] .…”