Heat-not-burn tobacco (IQOS), oral fibroblasts and keratinocytes: cytotoxicity, morphological analysis, apoptosis and cellular cycle. An in vitro study.

OBJECTIVES: The aim of this work is to investigate the biological effects of IQOS smoking on human gingival fibroblasts and human keratinocytes analysing cell viability, morphology, migration, apoptosis and cell cycle. BACKGROUND: Electronic cigarettes and tobacco heating systems have been marketed to reduce smoking damages caused by combustion. METHODS: Human gingival fibroblasts and human keratinocytes viability was determined by a colorimetric assay measuring mitochondrial dehydrogenase activity (MTT assay); after an in vitro exposure of 24 h, cell morphology was analysed with scanning electron microscope and cell migration was tested by Scratch assay, a method to mimic the migration of the cells during wound healing in vivo. Apoptosis and cell cycle were analysed with flow cytometry, and the expression of related genes (p53, Bcl2, p16 and p21) was indagated using real-time polymerase chain reaction. RESULTS: IQOS extracts increased both cell viability (23%-41% with fibroblasts and 30%-79% with keratinocytes) and migration. No morphological alterations were observed. IQOS extracts did not induced an increase in cell death, but rose the number of S- and G2/M-phase cells. IQOS extracts also significantly increased p53 expression by fibroblasts (undiluted and 6.25% dilution, 2- and 3.6-fold higher, respectively) and reduced both Bcl2 (about two- and fivefold, respectively) and p21 expressions (about twofold with both extracts), while on keratinocytes both undiluted and 6.25% dilution extracts increased Bcl2 expression (about four- and threefold higher, respectively) and reduced p53 expression (about two- and fivefold, respectively). CONCLUSION: IQOS smoke seemed to induce proliferation as highlighted by a viability assay, and migration and cell cycle analysis. The increased cell proliferation induced by IQOS devices must be carefully investigated for its possible clinical effects on oral cell populations.

Acute and chronic cannabidiol treatment: In vitro toxicological aspects on human oral cells.

Cannabidiol is gaining increasing interest for its potential anti-inflammatory, immunomodulatory, and antineoplastic effects. The purpose of this study is to investigate the biological effects of acute and chronic CBD administration on gingival fibroblasts and oral keratinocytes. Viability, morphology, migration, apoptosis and cell cycle, and expression of related genes (p53, BCL2, p21, and BAX) and of endocannabinoid system receptors (CB1, CB2 and GPR55) with real-time PCR and DNA damage with phospho-γ-H2AX immunofluorescence detection were analyzed. Concentrations between 100 µM and 0.001 µM were used: 50 µM (toxic dose), 25 µM (viability promoter), and 1 µM (nontoxic), were selected for subsequent chronic analysis. Acute treatment reveals significant effects than chronic, in particular in fibroblasts: concentrations ≥50 µM are highly cytotoxic, with increased apoptosis and reduced migration. Cell death correlates with increased p53 and BAX, followed by arrest in G0/G1 phase, with elevated p21 levels, suggesting a time- and dose-dependent damage. An increase in H2AX phosphorylation was observed with 25 µM and 50 µM, while 1 µM was biocompatible. Keratinocytes showed less cytotoxic effect than fibroblasts. Induced cell damage was dose- and time-related, with less damage after chronic treatment. Further investigations are needed with longer time frames to evaluate CBD dose- and time-dependent effects to identify an effective therapeutic dose.

In Vitro effects of alternative smoking devices on oral cells: Electronic cigarette and heated tobacco product versus tobacco smoke.

OBJECTIVE: To investigate the biological effects of electronic cigarette (e-cigarette) and heated tobacco product extracts respect to tobacco smoke extract on human gingival fibroblasts and human oral keratinocytes analysing cell viability, morphology, migration, apoptosis, cell cycle and epithelial-mesenchymal transition (EMT). DESIGN: Human gingival fibroblasts and human oral keratinocytes viability was analysed by MTT assay, cell morphology using scanning electron microscope (SEM) and cell migration by Scratch assay, a method that mimics the cell migration during wound healing in vivo. Apoptosis and cell cycle were analysed with flow cytometry and the related-gene expression of TP53, BCL2, CDKN2A and CDKN1A was indagated using real-time polymerase chain reaction. EMT process was analysed through expression of specific markers: CDH1, SNAI2, TWIST1, MMP2, FN1 and VIM. All investigations were evaluated after 24 h an in vitro exposure. RESULTS: Undiluted tobacco smoke extract induced significant inhibition of cell viability and cell migration, caused morphological alterations and induced an increase in cell death. No alterations or damage were observed after treatment with e-cigarette extracts. Heated tobacco product extract induced proliferation as highlighted by an increase of cell viability, cell migration and alterations of cycle analysis. CONCLUSIONS: Comparing the different cigarette extracts, tobacco smoke turns out to be the most harmful, e-cigarette did not determine morphological and functional alterations and heated tobacco product must be carefully investigated for its possible clinical effects on oral cell populations.

The hand in motion of liberals and conservatives reveals the differential processing of positive and negative information.

Recent research revealed that political conservatives and liberals differ in the processing of valenced information. In particular, conservatives (vs. liberals) tend to weigh negative information more than positive information in their perception of the physical and social world. In the present work, we further investigated the ideology-based asymmetries in the processing of negative and positive information examining both the attention-grabbing power of negative information and the trajectories of the movements performed by respondents when required to categorize positive and negative stimuli. To this end we employed a modified version of the Mouse-Tracking procedure (Freeman & Ambady, 2010), recording hand movements during the execution of categorization tasks. Results showed that conservatives were indeed slower to start and execute response actions to negative stimuli, and, more specifically, the trajectories of their movements signaled avoidance tendencies aimed at increasing the distance from negative stimuli. In addition, this pattern of findings emerged both when participants were asked to categorize the stimuli according to their valence and when the same stimuli had to be categorized on the basis of irrelevant perceptual features. Overall, results demonstrate that conservatives and liberals process valenced information differently, perform different spontaneous movements when exposed to them, and that such asymmetries are largely independent from current processing goals.

Implicit and explicit illusory correlation as a function of political ideology.

Research has demonstrated that people who embrace different ideological orientations often show differences at the level of basic cognitive processes. For instance, conservatives (vs. liberals) display an automatic selective attention for negative (vs. positive) stimuli, and tend to more easily form illusory correlations between negative information and minority groups. In the present work, we further explored this latter effect by examining whether it only involves the formation of explicit attitudes or it extends to implicit attitudes. To this end, following the typical illusory correlation paradigm, participants were presented with members of two numerically different groups (majority and minority) each performing either a positive or negative behaviour. Negative behaviors were relatively infrequent, and the proportion of positive and negative behaviors within each group was the same. Next, explicit and implicit (i.e., IAT-measured) attitudes were assessed. Results showed that conservatives (vs. liberals) displayed stronger explicit as well as implicit illusory correlations effects, forming more negative attitudes toward the minority (vs. majority) group at both the explicit and implicit level.