Oxidative actions of hydrogen peroxide in human gingival and oral periosteal fibroblasts: Responses to glutathione and nicotine, relevant to healing in a redox environment

Abstract

BackgroundThis study aims to validate pro-oxidant actions of nicotine (N), using hydrogen peroxide (H2O2) and the antioxidant glutathione (G) in an in vitro model of human gingival fibroblasts (HGF) and human oral periosteal fibroblasts (HPF); radiolabelled androgens are used as biomarkers of redox status. Oxidative stress is an important mediator of inflammatory repair. The androgen metabolite 5α-dihydrotestosterone (DHT) is an effective biomarker of oxidative stress and healing.Methods6 Cell-lines of HGF and HPF established in confluent monolayer culture were incubated in Eagle's MEM using 14C-testosterone and 14C-4-androstendione as substrate; in conjunction with effective concentrations of N, G and H2O2 established at N250, G3 μg/ml and 3%H2O2 w/w, 0.5 μl/ml. Combinations of H2O2G and H2O2GN were used in order to compare the oxidative effects of N/H2O2 and their responses to glutathione. At 24 h, the medium was solvent extracted, evaporated to dryness and subjected to TLC in a benzene/acetone solvent system 4:1 v/v for the separation of metabolites. The separated metabolites were quantified using a radioisotope scanner.ResultsThe mean trends of 6 cell-lines for both substrates and each cell type demonstrated that the yield of the main metabolite DHT was significantly reduced by N and H2O2 alone (2-fold, n=6; p<0.01). The inhibition caused by H2O2 was overcome by the antioxidant glutathione in the combination H2O2G, to values similar to those of controls (n=6; p<0.01). It is relevant that when N was added to this neutralized combination, the decrease in yields of DHT triggered by N were comparable to those induced by H2O2; and retaining the positive effect of G.ConclusionOxidative stress mediated by H2O2 was overcome by glutathione and recurred when nicotine was added, suggestive of a pro- oxidant role for nicotine. Androgen biomarkers are a sensitive index of oxidative stress which affects wound healing.

Cytotoxicity and apoptosis induction by e-cigarette fluids in human gingival fibroblasts

“…The vaping seemed to increase the reduction of cell metabolic activity, and this raise could be due to the presence of particles [27] and of various kinds of chemicals [30] in the aerosol generated from the cartomizer. Being that the pro-oxidative action of nicotine is well-known [11], we investigated the reactive oxygen species production, finding an increase after 24 h in the nicotine (vaped and not vaped)-treated samples, according to Kang et al [10]. Surprisingly, also, the nicotine-free fluids induced an increased ROS production after 24 h, indicating a role for the fluid itself in triggering the oxidative stress in HGFs.…”

“…There is morphological evidence of increased oxidative stress-induced apoptosis in HGFs with transient activation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinases (ERK) and concomitant activation of p38 evidenced by caspase-3 activation, and cleavage of poly ADP ribose polymerase (PARP). A recent study showed that oxidative stress mediated by H 2 O 2 was overcome by glutathione and recurred when nicotine was added, suggestive of a pro-oxidant role for nicotine [11]. Nicotine is also responsible for migration inhibition [4], cytoskeleton alteration [12], and extracellular matrix remodeling [13] in human gingival fibroblasts (HGFs), one of the cell types mostly exposed to smoking and vaping.…”

Antioxidant Response of Osteoblasts to Doxycycline in an Inflammatory Model Induced by C-reactive Protein and Interleukin-6

“…The formed DHT acts as substrate for subsequent conversion to diol. IL-6 and CRP had significant inhibitory effects on the synthesis of DHT, an effective marker of inflammation [ 5 ] and oxidative stress [ 15 - 17 ]. Concurrent incubation with doxycycline, which has anti-inflammatory and pro-anabolic actions, overcame these effects to a significantly greater extent than incubation with doxycycline alone; demonstrating effective applications for adjunctive doxycycline in an inflammatory milieu.…”

“…These effects are prevented by pre-treatment with DHT which increases levels of the antioxidant enzyme catalase; and reversed by the androgen receptor inhibitor flutamide, a non-steroidal androgen antagonist which competes for the same receptors as T and DHT due to its structural similarity [ 16 ] Androgen receptor (AR) proteins directly activated by DHT play an important role as redox regulators via direct actions on glutathione S-transferase. DHT as an effective marker of oxidative stress [ 17 ], is suitable for this application in our in vitro cell culture model.…”

The ways of free radical oxidation correction in the early posttraumatic period after the combined trauma of the chest and hips

“…Дослідження патогенетичних механізмів травми різного генезу свідчать про те, що клітинна й тканинна гіпоксія призводить до дисбалансу окиснювально-відновних про-цесів, мітохондріальної дисфункції, вивільнення прозапальних цитокінів, чинників клітинної ад-гезії, а це, у свою чергу, значно збільшує про-дукцію вільних радикалів [2]. Основними джере лами вільних радикалів є мітохондрії, ксантинок сидази, NAD(P)H-оксидази, а також велика кількість ендотеліальних факторів [3,4]. Дослі-дження показують, що оксидативний стрес у пацієнтів з різними видами травм розвивається практично відразу після початкового ушкоджен ня, переходячи з макроскопічного рівня на клітинний і молекулярний [5].…”