Effects of cigarette smoke and nicotine on cell viability, migration and myofibroblastic differentiation

Comparative effect of anthocyanin on proliferation and migration of human gingival fibroblasts in the absence or presence of nicotine

Background

Oral fibroblast malfunction can result in periodontal diseases. Nicotine can prolong the healing process as an irritant of oral tissues. Anthocyanins have been demonstrated to have potential benefits in preventing or treating smoking-related periodontal diseases. Cyanidin chloride's (CC's) potential in oral wound healing and the viability, proliferation, and migration of human gingival fibroblasts (HGFs) were examined in the presence and absence of nicotine by an in vitro study.

Methods

The effects of different nicotine concentrations (1, 2, 3, 4, and 5 mM) on the viability and proliferation of HGF cells were evaluated in the presence and absence of different CC concentrations (5, 10, 25, and 50 μM) using the quantitative MTT assay. The scratch test was performed to evaluate the migration of CC-treated cells in the presence of 2.5-mM nicotine.

Results

No cytotoxicity was observed at 1‒100 μM CC concentrations after 24, 48, and 72 hours of exposure to HGF cells. However, a concentration of 200 μM significantly reduced cell viability by about 20% at all the three-time intervals (P<0.05). Also, 3‒5-mM concentrations of nicotine significantly reduced cell viability in a dose- and time-dependent manner. Moreover, the understudied CC concentrations decreased nicotine's adverse effects on cell migration to some extent.

Conclusion

Although the understudied CC concentrations could not significantly reduce the adverse effects of understudied nicotine concentrations on the viability and proliferation of HGF cells, they were able to reduce the detrimental effects of nicotine on cell migration significantly.

A high-throughput cigarette smoke-treated bronchosphere model for disease-relevant phenotypic compound screening

Cigarette smoking (CS) is the leading cause of COPD, and identifying the pathways that are driving pathogenesis in the airway due to CS exposure can aid in the discovery of novel therapies for COPD. An additional barrier to the identification of key pathways that are involved in the CS-induced pathogenesis is the difficulty in building relevant and high throughput models that can recapitulate the phenotypic and transcriptomic changes associated with CS exposure. To identify these drivers, we have developed a cigarette smoke extract (CSE)-treated bronchosphere assay in 384-well plate format that exhibits CSE-induced decreases in size and increase in luminal secretion of MUC5AC. Transcriptomic changes in CSE-treated bronchospheres resemble changes that occur in human smokers both with and without COPD compared to healthy groups, indicating that this model can capture human smoking signature. To identify new targets, we ran a small molecule compound deck screening with diversity in target mechanisms of action and identified hit compounds that attenuated CSE induced changes, either decreasing spheroid size or increasing secreted mucus. This work provides insight into the utility of this bronchopshere model to examine human respiratory disease impacted by CSE exposure and the ability to screen for therapeutics to reverse the pathogenic changes caused by CSE.

Hormesis: wound healing and fibroblasts

Hormetic dose responses are reported here to occur commonly in the dermal wound healing process, with the particular focus on cell viability, proliferation, migration and collagen deposition of human and murine fibroblasts with in vitro studies. Hormetic responses were induced by a wide range of substances, including endogenous agents, pharmaceutical preparations, plant-derived extracts including many well-known dietary supplements, as well as physical stressor agents such as low-level laser treatments. Detailed mechanistic studies have identified common signaling pathways and their cross-pathway communications that mediate the hormetic dose responses. These findings complement and extend a similar comprehensive assessment concerning the occurrence of hormetic dose responses in keratinocytes. These findings demonstrate the generality of the hormetic dose response for key wound healing endpoints, suggesting that the hormesis concept has a fundamental role in wound healing, with respect to guiding strategies for experimental evaluation as well as therapeutic applications.

Cortactin in Lung Cell Function and Disease

Cortactin (CTTN) is an actin-binding and cytoskeletal protein that is found in abundance in the cell cortex and other peripheral structures of most cell types. It was initially described as a target for Src-mediated phosphorylation at several tyrosine sites within CTTN, and post-translational modifications at these tyrosine sites are a primary regulator of its function. CTTN participates in multiple cellular functions that require cytoskeletal rearrangement, including lamellipodia formation, cell migration, invasion, and various other processes dependent upon the cell type involved. The role of CTTN in vascular endothelial cells is particularly important for promoting barrier integrity and inhibiting vascular permeability and tissue edema. To mediate its functional effects, CTTN undergoes multiple post-translational modifications and interacts with numerous other proteins to alter cytoskeletal structures and signaling mechanisms. In the present review, we briefly describe CTTN structure, post-translational modifications, and protein binding partners and then focus on its role in regulating cellular processes and well-established functional mechanisms, primarily in vascular endothelial cells and disease models. We then provide insights into how CTTN function affects the pathophysiology of multiple lung disorders, including acute lung injury syndromes, COPD, and asthma.

Interaction between serum vitamin C levels and smoking on the periodontal condition in older adults

BACKGROUND AND OBJECTIVES

Several epidemiological studies have reported that smokers have a higher prevalence and severity of periodontal disease than do nonsmokers, and that smoking negatively affects nutritional status and is associated with a reduced intake of antioxidants, particularly vitamin C. The present investigation aimed to examine the relationship between serum vitamin C levels and smoking and its influence on the periodontal condition in older adults.

MATERIALS AND METHODS

A total of 353 respondents met the inclusion criteria and were enrolled in the present study. The periodontal status of the study participants was determined through examinations of one or more residual teeth, which included a measurement of the probing pocket depth (PPD) and clinical attachment level (CAL) at six regions of each tooth. Blood samples were collected during the dental examinations and then sent to a laboratory to evaluate serum vitamin C and cotinine levels. A serum cotinine concentration of 100 ng/ml was considered a relevant threshold for active smoking. After dividing the participants into two groups according to serum cotinine levels, Poisson regression analysis was carried out to compare vitamin C levels with the prevalence rate ratio (PRR) for periodontal condition markers for each group based on serum cotinine levels.

RESULTS

We evaluated differences in the PRR of serum vitamin C tertiles between participants with high (≥100 ng/ml) or low (<100 ng/ml) serum cotinine levels after adjusting for sex, the use of interdental brushes or dental floss, and the number of teeth. A negative tendency between the PRR of vitamin C tertiles for the PPD or CAL was seen for both groups. Especially, a bigger difference was observed in the group with high serum cotinine levels. The PRR of the first tertiles in the high serum cotinine group was 5.03, compared with 2.69 in the low serum cotinine group (relative risk: 1.9).

CONCLUSION

The results of this study suggest a potential association between vitamin C levels and the periodontal condition, which may be influenced by smoking status.

Cigarette Smoke Exposure Increases Glucose-6-phosphate Dehydrogenase, Autophagy, Fibrosis, and Senescence in Kidney Cells In Vitro and In Vivo

Cigarette smoke (CS) is a risk factor for chronic obstructive pulmonary disease. We attempted to investigate fully the possible effects of CS on kidney cells. We found that the viability of a human kidney proximal tubular epithelial cell line (HK-2 cells) was decreased after treatment with CS extract (CSE). In particular, the effects of CSE at low concentrations did not change the expression of apoptosis and necrosis. Furthermore, CSE increased autophagy- and fibrosis-related proteins in HK-2 cells. Senescence-related proteins and the senescence-associated secretory phenotype (SASP) increased after HK-2 cells were treated with CSE. In addition, both RNA sequencing and gene set enrichment analysis data revealed that glucose-6-phosphate dehydrogenase (G6PD) in the reactive oxygen species (ROS) pathway is responsible for the changes in CSE-treated HK-2 cells. CSE increased G6PD expression and its activity. Moreover, the inhibition of G6PD activity increased senescence in HK-2 cells. The inhibition of autophagy reinforced senescence in the CSE-treated cells. In a mouse model of CS exposure, CS caused kidney damage, including tubular injury and glomerulosclerosis. CS increased fibrosis, autophagy, and G6PD expression in kidney tissue sections. In conclusion, CS induced G6PD expression, autophagy, fibrosis, and senescence in kidney cells. G6PD has a protective role in CS-induced nephrotoxicity.

Vitamin C stimulates RNA expression of human gingival fibroblasts proliferation and adhesion in cigarette smokers: An in vitro study

Background

Smoking and the severity of periodontal disease have long been associated. In Saudi Arabia, tobacco smoking is rising, contributing to the increased demand for products that counter its detrimental effects. The antioxidant properties of vitamin C (vit C) make it a powerful countermeasure to tobacco toxicity. Observation of these effects on human gingival fibroblasts (hGFs) would suggest use of vitamin C in future dental applications.

Aim

To examine the proliferation, adhesion, and expression of extracellular RNA in human gingival fibroblasts extracted from cigarette smokers when compared to never-smokers, in association with vitamin C.

Materials and Methods

Human gingival fibroblasts were extracted from Periodontal free sites of healthy adult male participants. Group 1; consisted of Heavy cigarette smokers (n = 1) while group 2 was never-smokers (n = 1). Collected cells were cultured and subcultured in supplemented growth medium. Vitamin C was then induced in the medium at the experimental sixth passage. RNA expression analysis using quantitative reverse transcriptase-polymerase chain reaction was performed to analyze the adhesion, proliferation, and extracellular matrix expression.

Results

Expression of the adhesion gene (CD44) in the smoker group was significantly downregulated than never-smoker group (p-value = 0.024). After the induction of vitamin C, the smoker samples showed a significant improvement in their gene expression levels. The extracellular genes involved in this study (COL1A1, LAMA3, and TGFB3) were significantly affected by the smoking status. In addition, the proliferation of MK167 and CCNB1 genes in smokers and never-smokers was increased.

Conclusion

Cigarette smoking affects the overall properties of human gingival fibroblasts’ adhesion, proliferation, and extra-cellular matrix formation. Furthermore, the addition of vitamin C affects these cellular properties in a positive manner.

ZC3H4 promotes pulmonary fibrosis via an ER stress-related positive feedback loop

BACKGROUND

Pulmonary fibrosis is a sequela of many pulmonary diseases, such as pneumoconiosis and idiopathic pulmonary fibrosis. The principal characteristics of pulmonary fibrosis comprise myofibroblast proliferation, alveolar damage and deposition of extracellular matrix components, which cause abnormal lung structure remodeling and an irreversible decline in lung function; however, the detailed mechanisms remain unclear. The current study focused on the role of ZC3H4, a new member of the zinc finger protein family, in SiO₂-induced pulmonary fibrosis.

METHODS

The expression of ZC3H4 and fibroblast activation markers (COL1A1, COL3A1 and ACTA1) was measured by western blotting and immunofluorescence staining after SiO₂ exposure (50 μg/cm²). The functional change in fibroblasts was studied with a scratch assay and a 3D migration assay. The CRISPR/Cas9 system was used to explore the regulatory mechanisms of ZC3H4 in pulmonary fibroblast cells.

RESULTS

The expression levels of ZC3H4 and sigmar1 (a key regulator of ER stress) were increased in pulmonary fibroblast cells and were associated with fibroblast activation, as indicated by the increase in COL1A1, COL3A1 and ACTA1, as well as the migration ability. SiO₂-enhanced fibroblast activation was attenuated by specific knockdown of ZC3H4 and inhibition of ER stress, demonstrating that ZC3H4 activated fibroblasts via the sigmar1/ER stress pathway. Interestingly, ER stress blockade also inhibited ZC3H4 expression, indicating the positive feedback regulatory mechanism of ER stress on ZC3H4.

CONCLUSIONS

Our results demonstrate that ZC3H4 and sigmar1 might act as novel therapeutic targets for silicosis, providing a reference for further pulmonary fibrosis research.

The role of cancer stromal fibroblasts in mediating the effects of tobacco-induced cancer cell growth

Tobacco products cause a variety of cancers, nicotine and carcinogens are two major factors to link the tobacco products and various cancers. The mechanism of tobacco inducing carcinogenesis and promoting cancer progression have been studied for a long time. However, mainstream studies just focus on the mutagenic characteristics of tobacco product and its properties to induce carcinogenesis of epithelial cells. In the past decades, people began to aware of the significant role of tumor stroma in cancer development and progression. Fibroblasts, which is associated with various cancer in all stage of disease progression, are the dominant cell type in the tumor microenvironment. While only a few studies explore the crosstalk between tobacco-induced fibroblasts and surrounding epithelial cells. Our purpose is to systematically review the effects of tobacco products on fibroblasts and further discuss how these effects affect the development of cancer cells.

Increased Monocyte-Derived CD11b+ Macrophage Subpopulations Following Cigarette Smoke Exposure Are Associated With Impaired Bleomycin-Induced Tissue Remodelling

Rationale

The accumulation of macrophages in the airways and the pulmonary interstitium is a hallmark of cigarette smoke-associated inflammation. Notably, pulmonary macrophages are not a homogenous population but consist of several subpopulations. To date, the manner in which cigarette smoke exposure affects the relative composition and functional capacity of macrophage subpopulations has not been elucidated.

Methods

Using a whole-body cigarette smoke exposure system, we investigated the impact of cigarette smoke on macrophage subpopulations in C57BL/6 mice using flow cytometry-based approaches. Moreover, we used bromodeoxyuridine labelling plus Il1a^-/- and Il1r1^-/- mice to assess the relative contribution of local proliferation and monocyte recruitment to macrophage accumulation. To assess the functional consequences of altered macrophage subpopulations, we used a model of concurrent bleomycin-induced lung injury and cigarette smoke exposure to examine tissue remodelling processes.

Main Results

Cigarette smoke exposure altered the composition of pulmonary macrophages increasing CD11b⁺ subpopulations including monocyte-derived alveolar macrophages (Mo-AM) as well as interstitial macrophages (IM)1, -2 and -3. The increase in CD11b⁺ subpopulations was observed at multiple cigarette smoke exposure timepoints. Bromodeoxyuridine labelling and studies in Il1a^-/- mice demonstrated that increased Mo-AM and IM3 turnover in the lungs of cigarette smoke-exposed mice was IL-1α dependent. Compositional changes in macrophage subpopulations were associated with impaired induction of fibrogenesis including decreased α-smooth muscle actin positive cells following intratracheal bleomycin treatment. Mechanistically, in vivo and ex vivo assays demonstrated predominant macrophage M1 polarisation and reduced matrix metallopeptidase 9 activity in cigarette smoke-exposed mice.

Conclusion

Cigarette smoke exposure modified the composition of pulmonary macrophage by expanding CD11b⁺ subpopulations. These compositional changes were associated with attenuated fibrogenesis, as well as predominant M1 polarisation and decreased fibrotic activity. Overall, these data suggest that cigarette smoke exposure altered the composition of pulmonary macrophage subpopulations contributing to impaired tissue remodelling.

Aqueous extract of tobacco induces mitochondrial potential dependent cell death and epithelial-mesenchymal transition in gingival epithelial cells

Smokeless tobacco habits are detrimental to oral health. A correlation between tobacco use and local epithelial tissue damage exists. Yet, the underlying cellular mechanism is not precisely characterized. This study assessed the dose-dependent action of Smokeless tobacco extract on gingival epithelial cells. Gingival tissue was taken from 5 healthy donors. Gingival epithelial cells were isolated by an enzymatic method and cultured up to passage 2. The cultured cells were treated with smokeless tobacco extract at 10%, 25%, 50%, and 75% volume concentration. After 48 h of incubation, MTT assay, Annexin V/PI assay, and DiIC1(5) assay were used to evaluate viability, apoptosis, and mitochondrial potential of the cells. RT-qPCR was used to determine the expression of BAX, BCL2, ECAD, NCAD, and TWIST. The Smokeless tobacco extract reduced cell viability by disrupting the mitochondrial potential and inducing apoptosis. Further, the Smokeless tobacco extract induced a dose-dependent epithelial-mesenchymal-transition in gingival epithelial cells. Apoptotic cellular death caused by tobacco extract on the gingival epithelial system was dependant on the mitochondrial potential of the cell. The results demonstrate that smokeless tobacco causes detrimental metabolic alterations of the periodontium.

Featured application

This study elucidates the mechanism by which Smokeless tobacco products cause cellular damage to the gingival epithelium. The use of Smokeless tobacco products can lead to major cellular and surface changes in the gingiva and its appearance. The consequences of these changes are not limited to oral cancer but also increases a person's risk for dental and periodontal disease.

E-cigarette aerosol induced cytotoxicity, DNA damages and late apoptosis in dynamically exposed A549 cells

In this study, the acute toxicological impacts associated with electronic cigarettes consumption were determined using a novel dynamic exposure methodology. The methodology was deployed to test various e-cigarette generated aerosols in A549 cell cultures. The e-liquid chemical profiling was achieved using GC-MS analysis while toxicity of diluted e-liquids aerosols was reported using numerous cytotoxicity assays. The presented findings pointed to acute aerosol exposure (thirty puffs at 40 W of power and higher) inducing significant cytotoxic, genotoxic, and apoptotic induction in exposed cells. These findings highlighted the significant risks posed by e-cigarette usage. The proposed methodology proved to be a useful tool for future screening of e-liquids generated aerosols toxicity. Future research is needed to establish the chronic toxicity resulting from long-term e-cigarette consumption.

E-Liquid Containing a Mixture of Coconut, Vanilla, and Cookie Flavors Causes Cellular Senescence and Dysregulated Repair in Pulmonary Fibroblasts: Implications on Premature Aging

Electronic cigarette (e-cig) usage has risen dramatically worldwide over the past decade. While they are touted as a safe alternative to cigarettes, recent studies indicate that high levels of nicotine and flavoring chemicals present in e-cigs may still cause adverse health effects. We hypothesized that an e-liquid containing a mixture of tobacco, coconut, vanilla, and cookie flavors would induce senescence and disrupt wound healing processes in pulmonary fibroblasts. To test this hypothesis, we exposed pulmonary fibroblasts (HFL-1) to e-liquid at varying doses and assessed cytotoxicity, inflammation, senescence, and myofibroblast differentiation. We found that e-liquid exposure caused cytotoxicity, which was accompanied by an increase in IL-8 release in the conditioned media. E-liquid exposure resulted in elevated senescence-associated beta-galactosidase (SA-β-gal) activity. Transforming growth factor-β1 (TGF-β1) induced myofibroblast differentiation was inhibited by e-liquid exposure, resulting in decreased α-smooth muscle actin and fibronectin protein levels. Together, our data suggest that an e-liquid containing a mixture of flavors induces inflammation, senescence and dysregulated wound healing responses.

Electronic cigarette vapor increases Streptococcus mutans growth, adhesion, biofilm formation, and expression of the biofilm-associated genes

OBJECTIVE

It still not known whether electronic cigarettes (e-cigarettes) contribute to dental caries. This study aimed to evaluate the effect of e-cigarettes on the growth of Streptococcus mutans, the formation of biofilm, and the expression of certain virulence genes.

MATERIALS AND METHODS

Streptococcus mutans cells were exposed or not to e-cigarettes with and without nicotine or to cigarette smoke twice a day for 15 min each exposure period. The bacterial growth and the expression of glucosyltranferase, competence, and glucan-binding genes were evaluated after 24 hr. Biofilm formation was assessed after 1, 2, and 3 days. S. mutans adhesion and growth to e-cigarette exposed human teeth were assessed.

RESULTS

We observed an increase in S. mutans growth with e-cigarettes, mainly at the early culture period. This was confirmed by an increase of biofilm mass ranging from 8 ± 0.5 mg with the control to 47 ± 5 mg after six exposures to nicotine-rich e-cigarettes. S. mutans cells adhered better to e-cigarette exposed teeth. E-cigarettes increased the expression of glucosyltranferase, competence, and glucan-binding genes.

CONCLUSIONS

E-cigarettes increased the growth of S. mutans and the expression of virulent genes. E-cigarettes promoted the adhesion to, and formation of biofilms on teeth surfaces.

Inhibitory effects of cigarette smoke extracts on neural differentiation of mouse embryonic stem cells

Maternal smoking during the perinatal period is linked to adverse neonatal outcomes such as low birth weight and birth defects. Numerous studies have shown that cigarette smoke or nicotine exposure has a widespread effect on fetal nerve development. However, there exists a lack of understanding of what specific changes occur at the cellular level on persistent exposure to cigarette smoke during the differentiation of embryonic stem cells (ESCs) into neural cells. We previously investigated the effects of cigarette smoke extract (CSE) and its major component, nicotine, on the neural differentiation of mouse embryonic stem cells (mESCs). Differentiation of mESCs into neural progenitor cells (NPCs) or neural crest cells (NCCs) was induced with chemically defined media, and the cells were continuously exposed to CSE or nicotine during neural differentiation and development. Disturbed balance of the pluripotency state was observed in the NPCs, with consequent inhibition of neurite outgrowth and glial fibrillary acidic protein (Gfap) expression. These inhibitions correlated with the altered expression of proteins involved in the Notch-1 signaling pathways. The migration ability of NCCs was significantly decreased by CSE or nicotine exposure, which was associated with reduced protein expression of migration-related proteins. Taken together, we concluded that CSE and nicotine inhibit differentiation of mESCs into NPCs or NCCs, and may disrupt functional development of neural cells. These results imply that cigarette smoking during the perinatal period potentially inhibits neural differentiation and development of ESCs cells, leading to neonatal abnormal brain development and behavioral abnormalities.

Cigarette smoke extract inhibits cell migration and contraction via the reactive oxygen species/adenosine monophosphate-activated protein kinase pathway in nasal fibroblasts

BACKGROUND

Fibroblast migration plays a significant role in wound healing after endoscopic sinonasal surgery. Cigarette smoke extract (CSE) is a potent inhibitor of fibroblast functions including cell proliferation and migration. The purpose of the study was to determine the influence of CSE on migration and collagen gel contraction in nasal fibroblasts and investigate its underlying mechanisms.

METHODS

Fibroblast migration was evaluated using wound healing assay and transwell migration assay. Contractile activity was assessed by collagen gel contraction assay. Reactive oxygen species (ROS) were quantified by 2',7'-dichlorofluorescein diacetate. Fibroblasts were treated with CSE and N-acetylcysteine (NAC), metformin, compound C, or transfected with small interfering RNA (siRNA) to suppress adenosine monophosphate-activated protein kinase (AMPK) expression. AMPK activation was determined by Western blot.

RESULTS

CSE and metformin were found to significantly reduce the migration and collagen gel contraction activity of nasal fibroblasts. Conversely, pretreatment with NAC and compound C significantly enhanced the migration and collagen gel contraction activity of fibroblasts. ROS production and AMPK phosphorylation were found to be significantly induced by CSE treatment, whereas the activity was inhibited on treatment with NAC, metformin, compound C, or AMPK siRNA. Silencing of AMPK expression was found to significantly reverse the suppressive effect of CSE in nasal fibroblasts.

CONCLUSION

CSE has an inhibitory effect on cell migration and collagen gel contraction activity via the ROS/AMPK signaling pathway in nasal fibroblasts.

Nicotine Suppresses the Invasiveness of Human Trophoblasts by Downregulation of CXCL12 Expression through the Alpha-7 Subunit of the Nicotinic Acetylcholine Receptor

Smoke exposure during pregnancy has detrimental effects upon numerous fetal and neonatal outcomes. Nicotine (the main component of tobacco) has been suggested to affect placental development. During placental development, efficient invasion by trophoblasts is required for establishment of the fetus–maternal circulation. In this study we explored the regulation of trophoblast invasion by nicotine. An immortalized first trimester extravillous trophoblast cell line (HTR-8/SVneo cells) was used for all the experiments, which were treated by nicotine, methyllycaconitine, and C-X-C motif chemokine ligand 12 (CXCL12). Total RNA and protein were used to study the expressions of nicotinic acetylcholine receptors (nAChRs), and transwell assay was used to study invasiveness. Changes of RNA expression due to nicotine treatment were detected by RNA sequence. Level of CXCL12 mRNA was verified by quantitative PCR. We showed that HTR-8/SVneo expressed subunits α2–4, α7, α9, β1, and β2 of nAChRs. Nicotine downregulated CXCL12 expression and inhibited trophoblast invasion. Methyllycaconitine, as an antagonist of the α7 homopolymer, blocked the inhibitory effect of nicotine. CXCL12 could rescue the nicotine-induced inhibitory effect on invasion of HTR-8/SVneo cells. These results suggest that the α7 subunit of the nAChR has important roles in modulating trophoblast invasion through CXCL12.

Biological Effects of Shikonin in Human Gingival Fibroblasts via ERK 1/2 Signaling Pathway

Shikonin, an active ingredient of Lithospermum erythrorhizon, exerts anti-inflammatory and antibacterial effects, and promotes wound healing. We investigated whether shikonin stimulated gingival tissue wound healing in human gingival fibroblasts (hGF). In addition, we evaluated the effects of shikonin on the mitogen-activated protein kinase (MAPK) signaling pathway, which has an important role in wound healing. hGF were subjected to primary culture using gingiva collected from patients. The cells were exposed to/treated with Shikonin at concentrations ranging from 0.01 to 100 μM. The optimal concentration was determined by cell proliferation and migration assays. Type I collagen and fibronectin synthesis, the gene expression of vascular endothelial growth factor (VEGF) and FN, and the phosphorylation of Extracellular signal-regulated kinase (ERK) 1/2 were investigated. Identical experiments were performed in the presence of PD98059 our data suggest, a specific ERK 1/2 inhibitor. Shikonin significantly promoted hGF proliferation and migration. Shikonin (1 µM) was chosen as the optimal concentration. Shikonin promoted type I collagen and FN synthesis, increased VEGF and FN expression, and induced ERK 1/2 phosphorylation. These changes were partially suppressed by PD98059. In conclusion, Shikonin promoted the proliferation, migration, type I collagen and FN synthesis, and expression of VEGF and FN via ERK 1/2 signaling pathway in hGFs. Therefore, shikonin may promote periodontal tissue wound healing.

Soluble Wood Smoke Extract Promotes Barrier Dysfunction in Alveolar Epithelial Cells through a MAPK Signaling Pathway

Wildfire smoke induces acute pulmonary distress and is of particular concern to risk groups such as the sick and elderly. Wood smoke (WS) contains many of the same toxic compounds as those found in cigarette smoke (CS) including polycyclic aromatic hydrocarbons, carbon monoxide, and free radicals. CS is a well-established risk factor for respiratory diseases such as asthma and COPD. Limited studies investigating the biological effects of WS on the airway epithelium have been performed. Using a cell culture-based model, we assessed the effects of a WS-infused solution on alveolar epithelial barrier function, cell migration, and survival. The average geometric mean of particles in the WS was 178 nm. GC/MS analysis of the WS solution identified phenolic and cellulosic compounds. WS exposure resulted in a significant reduction in barrier function, which peaked after 24 hours of continuous exposure. The junctional protein E-cadherin showed a prominent reduction in response to increasing concentrations of WS. Furthermore, WS significantly repressed cell migration following injury to the cell monolayer. There was no difference in cell viability following WS exposure. Mechanistically, WS exposure induced activation of the p44/42, but not p38, MAPK signaling pathway, and inhibition of p44/42 phosphorylation prevented the disruption of barrier function and loss of E-cadherin staining. Thus, WS may contribute to the breakdown of alveolar structure and function through a p44/42 MAPK-dependent pathway and may lead to the development and/or exacerbation of respiratory pathologies with chronic exposure.

Role of myofibroblasts in normal and pathological periodontal wound healing

Myofibroblasts represent specific subpopulations of cells with important roles in tissue remodeling in both health and disease. They are not usually found in resting healthy tissues. However, they increase in number during the proliferative phase of wound healing. In these conditions, myofibroblasts secrete and organize different molecular components of the extracellular matrix that with time will reconstitute and hopefully regenerate the damaged tissue. Importantly, these cell populations must be eliminated after wound healing has been completed. However, deficiencies in their differentiation or the persistence of this cell population has been associated with the development of delayed wound healing and fibrosis, respectively. In the present review, we analyze the involvement of myofibroblasts in periodontal wound healing and their potential contribution to tissue homeostasis and disease.

Comparative study of the effects of cigarette smoke and electronic cigarettes on human gingival fibroblast proliferation, migration and apoptosis

In an effort to reduce smoking-related diseases, alternative products such as e-cigarettes have been proposed. However, despite their growing popularity, the potential toxicity of e-cigarettes remains largely unknown. In this study, human gingival fibroblasts were repeatedly exposed to cigarette smoke condensate (CSC) and to nicotine-rich (NR) or nicotine-free (NF) e-vapor condensates for 60 min once a day for various time periods. They were then used to perform different analyses. Results indicate that cells exposed to CSC or NR condensates showed an altered morphology and a reduced proliferation rate, as ascertained by MTT and BrdU assays. Fibroblast cultures exposed to either CSC or e-vapor condensates also showed increased levels of TUNEL-positive apoptotic cells, compared to that recorded in the control. Furthermore, the cell scratch test revealed that repeated exposures to CSC or to e-vapor condensates delayed both fibroblast migration and wound healing. It should be noted that CSC was much more damageable to gingival fibroblasts than were the NR and NF e-vapor condensates. The representative chain of damage thus translates to CSC > NR e-vapor condensate > NF e-vapor condensate.

Effect of smoking cessation in saliva compounds by FTIR spectroscopy

INTRODUCTION

Smoking is currently considered one of the biggest risk factors for the development of various diseases and early death. Fourier transform infrared (FTIR) spectroscopy is a valuable tool for analysis of biofluids such as saliva and is considered useful for diagnostic purposes. The aim of this study was to evaluate the effect of smoking cessation on saliva composition by FTIR spectroscopy.

METHODS

We analyzed the saliva of participants in two groups: a smoker group made up of 10 chronic smokers and a former smoker group made up of 10 individuals who had stopped smoking. Members of both groups had similar smoking history.

RESULTS

The results showed few differences in spectral intensity between the groups; however, spectral peaks were slightly increased in the group of smokers in the bands for DNA, indicating modification of its content or cell necrosis. They were also increased for the mannose-6-phosphatase molecule, which is expressed in prostate and breast carcinomas. In the former smoker group, the peak of thyociante was decreased and the band referring to collagen increased in intensity, which indicates a better tissue regeneration capacity.

CONCLUSION

Considering these results and the fact that tobacco intake was similar between the groups, it can be concluded that there was recovery of tissue regeneration capacity with smoking cessation during the study period, although the effects found in smokers persisted in the bodies of those who had given up smoking.

The effect of nicotine and cotinine on human gingival fibroblasts attachment to root surfaces

BACKGROUND

Different compounds of smoking (e.g., nicotine and cotinine) are risk factors for various diseases such as oral cancer and periodontal diseases. Some studies reported the negative effects of nicotine on cell proliferation and differentiation. The present in vitro study assessed the effects of nicotine and cotinine (long-acting metabolite of nicotine) on the attachment and viability of human gingival fibroblast (HGF) cells to tooth root surfaces.

METHODS

A total of 70 teeth specimens were placed into 48-well culture plates and covered with HGF cell suspension, in complete Dulbecco's modified Eagle's medium culture medium containing 1 nM, 1 μm, 1 mM, and 5 mM of nicotine and cotinine concentrations. Cellular attachment and viability measured using an MTT assay and a scanning electron microscope were used for cell morphological evaluation.

RESULTS

After 24 h, low (nanomolar and micromolar) and high concentrations (millimolar) of nicotine and cotinine caused a significant reduction in the initial cell adhesion in comparison with the control group, but no significant difference was observed between the nicotine and the cotinine groups (p<0.05). Dentally attached cells with low concentrations of nicotine and cotinine proliferated 48 h after exposure, the same as the control group. However, dentally attached cells with high concentrations of nicotine and cotinine (especially 5 mM) did not proliferate 24 h after exposure (p<0.05).

CONCLUSIONS

Low concentrations of nicotine and cotinine caused a reduction in the initial cell adhesion. However, no significant adverse effects on the proliferation of attached cells were seen in the longer period. High concentrations of nicotine and cotinine have adverse effects on the cell adhesion and proliferation of HGF cells.

MCPIP1 Regulates Alveolar Macrophage Apoptosis and Pulmonary Fibroblast Activation After in vitro Exposure to Silica

BACKGROUND

Silicosis is a fatal and fibrotic pulmonary disease caused by the inhalation of silica. After arriving at the alveoli, silica is ingested by alveolar macrophages (AMOs), in which monocyte chemotactic protein-induced protein 1 (MCPIP1) plays an essential role in controlling macrophage-mediated inflammatory responses. However, the mechanism of action of MCPIP1 in silicosis is poorly understood.

METHODS

Primary rat AMOs were isolated and treated with SiO2 (50 µg/cm(2)). MCPIP1 and AMO activation/apoptosis markers were detected by immunoblotting. MCPIP1 was down-regulated using siRNA in AMOs. The effects of AMOs on fibroblast activation and migration were evaluated using a gel contraction assay, a scratch assay, and a nested collagen matrix migration model.

RESULTS

After exposure to SiO2, MCPIP1 was significantly increased in rat AMOs. Activation and apoptosis markers in AMOs were up-regulated after exposure to SiO2 Following siRNA-mediated silencing of MCPIP1 mRNA, the markers of AMO activation and apoptosis were significantly decreased. Rat pulmonary fibroblasts (PFBs) cultured in conditional medium from AMOs treated with MCPIP1 siRNA and SiO2 showed significantly less activation and migration compared with those cultured in conditional medium from AMOs treated with control siRNA and SiO2 CONCLUSION: Our data suggest a vital role for MCPIP1 in AMO apoptosis and PFB activation/migration induced by SiO2.

MCPIP1 mediates silica-induced cell migration in human pulmonary fibroblasts

Silicosis is a systemic disease caused by inhaling silicon dioxide (SiO2). Phagocytosis of SiO2 in the lungs initiates an inflammatory cascade that results in fibroblast proliferation and migration followed by fibrosis. According to previous data from our laboratory, monocyte chemotactic protein-1 (MCP-1) plays a critical role in fibroblast proliferation and migration in conventional two-dimensional (2D) monolayer cultures. The present study aimed to explore the downstream cascade of MCP-1 in both 2D and three-dimensional (3D) cell culture models of silicosis. Experiments using primary cultured adult human pulmonary fibroblasts (HPF-a) demonstrated the following: 1) SiO2 treatment induces expression of MCP-1-induced protein (MCPIP1) in a time- and dose-dependent manner in both 2D and 3D cultures; 2) the MAPK and phosphatidylinositol-3-kinase (PI3K)/Akt pathways are involved in SiO2-induced MCPIP1 expression; and 3) MCPIP1 induction mediates the SiO2-induced increase in cell migration in both 2D and 3D cultures. The effect of MCP-1 in silicosis occurs mainly through MCPIP1, which, in turn, mediates the observed SiO2-induced increase in pulmonary fibroblast migration. However, the time frame for MCPIP1 induction differed between 2D and 3D cultures, indicating that, compared with conventional 2D cell culture systems, 3D culture may be useful for analyses of fibroblast physiology under conditions that more closely resemble in vivo environments. Our study determined the link between fibroblast-derived MCPIP1 and SiO2-induced cell migration, and this finding provides novel evidence of the potential of MCPIP1 in the development of novel therapeutic strategies for silicosis.

Alcohol and cigarette smoke components activate human pancreatic stellate cells: implications for the progression of chronic pancreatitis

BACKGROUND

Chronic pancreatitis, a known complication of alcohol abuse, is characterized histopathologically by prominent fibrosis. Pancreatic stellate cells (PSCs) are responsible for producing this fibrous tissue in chronic pancreatitis and are activated by alcohol. Progression of alcoholic chronic pancreatitis (as assessed by calcification and fibrosis) is thought to be facilitated by concurrent smoking, but the mechanisms are unknown. This study aimed to (a) determine whether human PSCs (hPSCs) and rat PSCs express nicotinic acetylcholine receptors (nAChRs), which are known to bind 2 important components of cigarette smoke, namely nicotine and nicotine-derived nitrosamine ketone (NNK), and (b) examine the effects of cigarette smoke components in the presence and absence of alcohol on PSC activation in vitro.

METHODS

Western blotting was used to detect the presence of nAChRs in primary cultures of PSCs. Clinically relevant concentrations of cigarette smoke components (either cigarette smoke extract [CSE], NNK, or nicotine) ± ethanol (EtOH) were used to treat primary cultures of PSCs, and stellate cell activation was assessed by cell migration, proliferation, collagen production, and apoptosis.

RESULTS

We demonstrate, for the first time, that PSCs express nAChRs (isoforms α3, α7, β, ε) and that the expression of the α7 isoform in hPSCs is induced by CSE + EtOH. We also provide novel findings that PSCs are activated by CSE and NNK (both alone and in combination with EtOH) as evidenced by an increase in cell migration and/or proliferation. Further, we demonstrate that activation of PSCs by CSE + EtOH and NNK + EtOH may be mediated via nAChRs on the cells.

CONCLUSIONS

PSCs are activated by clinically relevant concentrations of cigarette smoke components (CSE and NNK), alone and in combination with EtOH. Thus, in alcoholics who smoke, progression of pancreatic fibrosis may be facilitated by the combined effects of alcohol and cigarette smoke components on hPSC behavior.

Smoking Modulates Gene Expression of Type I Collagen, Bone Sialoprotein, and Osteocalcin in Human Alveolar Bone

PURPOSE

Previous animal studies have shown the negative impact of smoking on bone-to-implant contact, and in humans, a decrease in bone density and implant survival over time. However, the effect of smoking on the human alveolar bone regarding the expression of bone-related markers is unknown. Therefore, the aim of this study was to evaluate the influence of smoking on the gene expression of molecules of bone metabolism in alveolar bone tissue from sites designed to receive dental implants.

MATERIALS AND METHODS

Biopsy specimens of alveolar bone were collected from smokers (n = 19) and nonsmokers (n = 19) from areas planned to receive dental implants. Gene expression of tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, osteoprotegerin (OPG), type I collagen (COL-I), bone sialoprotein (BSP), and osteocalcin (OCN) was quantified by quantitative real-time polymerase chain reaction using glyceraldehyde-3-phosphate dehydrogenase as a reference gene. The results were assessed using multiple regression analysis, with a significance level of 5%.

RESULTS

Multiple regression analysis indicated that smoking negatively affected mRNA expression of BSP and OCN and positively altered the expression of COL-I (P < .05) despite age, gender, and arch. Moreover, regression analysis did not show a significant correlation between smoking habit and mRNA levels of TNF-α, TGF-β, and OPG (P > .05).

CONCLUSION

These results support the hypothesis that some bone markers in alveolar tissue are modulated by smoking, which could explain the negative impact of smoking on bone healing.

Cigarette smoke condensate inhibits collagen gel contraction and prostaglandin E2 production in human gingival fibroblasts

BACKGROUND

Granulation tissue remodeling and myofibroblastic differentiation are critically important events during wound healing. Tobacco smoking has a detrimental effect in gingival tissue repair. However, studies evaluating the effects of cigarette smoke on these events are lacking.

MATERIAL AND METHODS

We used gingival fibroblasts cultured within free-floating and restrained collagen gels to simulate the initial and final steps of the granulation tissue phase during tissue repair. Collagen gel contraction was stimulated with serum or transforming growth factor-β1. Cigarette smoke condensate (CSC) was used to evaluate the effects of tobacco smoke on gel contraction. Protein levels of alpha-smooth muscle actin, β1 integrin, matrix metalloproteinase-3 and connective tissue growth factor were evaluated through Western blot. Prostaglandin E(2) (PGE(2)) levels were determined through ELISA. Actin organization was evaluated through confocal microscopy.

RESULTS

CSC reduced collagen gel contraction induced by serum and transforming growth factor-β1 in restrained collagen gels. CSC also altered the development of actin stress fibers in fibroblasts cultured within restrained collagen gels. PGE(2) levels were strongly diminished by CSC in three-dimensional cell cultures. However, other proteins involved in granulation tissue remodeling and myofibroblastic differentiation such as alpha-smooth muscle actin, β1 integrin, matrix metalloproteinase-3 and connective tissue growth factor, were unmodified by CSC.

CONCLUSIONS

CSC may alter the capacity of gingival fibroblasts to remodel and contract a collagen matrix. Inhibition of PGE(2) production and alterations of actin stress fibers in these cells may impair proper tissue maturation during wound healing in smokers.

Cigarette smoke condensate modulates migration of human gingival epithelial cells and their interactions with Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

Epithelial cells are recognized as the first line of defense against bacterial infection and environmental harmful stimuli such as cigarette smoke (CS). Although previous studies explored the effects of nicotine on host cells, mechanisms by which CS affects cellular functions remain uncertain. The present study investigated the effects of CS condensate (CSC) on in vitro wound closure of gingival epithelial cells and their potential interactions with a major periodontal pathogen, Porphyromonas gingivalis.

MATERIAL AND METHODS

Human gingival epithelial cells (Ca9-22) were treated with CSC for 24 h. Cell proliferation was determined using a WST-1 assay. Cell migration was assessed using a wound closure model. The expression of integrins was analyzed by confocal scanning laser microscopy and real-time PCR. Intracellular invasion of P. gingivalis was evaluated by confocal scanning laser microscopy and an antibiotic protection assay.

RESULTS

Low concentrations (1-10 μg/mL) of CSC showed no significant effect on cell proliferation. CSC demonstrated dual effects on epithelial wound closure of Ca9-22 cells: high concentrations (i.e. 250 μg/mL) significantly inhibited the wound closure whereas low concentrations (i.e. 10 μg/mL) promoted it (p < 0.01). CSC induced distinct changes in cytoskeleton. When CSC-exposed cells were infected with P. gingivalis for 2 h, a significant inhibition of wound closure was observed concurrent with a decrease in integrin α3 expression near the wound area. A significantly increased P. gingivalis invasion into Ca9-22 was observed when exposed to low concentrations of CSC.

CONCLUSION

Low concentrations of CSC increased invasion of human gingival epithelial cells by P. gingivalis and induced changes in cytoskeleton and integrin expression, thereby modulating the cell migration.

Influence of E-smoking liquids on human periodontal ligament fibroblasts

Introduction

Over the last years, electronic cigarettes (ECs) have become more popular, particularly in individuals who want to give up smoking tobacco. The aim of the present study was to assess the influence of the different e-smoking liquids on the viability and proliferation of human periodontal ligament fibroblasts.

Method and materials

For this study six test solutions with components from ECs were selected: lime-, hazelnut- and menthol-flavored liquids, nicotine, propylene glycol, and PBS as control group. The fibroblasts were incubated up to 96 h with the different liquids, and cell viability was measured by using the PrestoBlue^® reagent, the ATP detection and the migration assay. Fluorescence staining was carried out to visualize cell growth and morphology. Data were statistically analyzed by two-tailed one-way ANOVA.

Results

The cell viability assay showed that the proliferation rates of the cells incubated with nicotine or the various flavored liquids of the e-cigarettes were reduced in comparison to the controls, though not all reductions were statistically significant. After an incubation of 96 h with the menthol-flavored liquid the fibroblasts were statistically significant reduced (p < 0.001). Similar results were found for the detection of ATP in fibroblasts; the incubation with menthol-flavored liquids (p < 0.001) led to a statistically significant reduction. The cell visualization tests confirmed these findings.

Conclusion

Within its limits, the present in vitro study demonstrated that menthol additives of e-smoking have a harmful effect on human periodontal ligament fibroblasts. This might indicate that menthol additives should be avoided for e-cigarettes.

Nicotine affects cutaneous wound healing in stressed mice

Stress is an important condition of modern life. Nicotine addiction can modulate the physiological response to stress. Cutaneous healing is a complex process resulting in scar formation, which can be delayed by stress. Therefore, the aim of this study was to investigate the effects of nicotine administration on cutaneous wound healing in chronically stressed mice. Male mice were submitted to rotational stress, whereas control animals were not subjected to stress. These stressed and control animals were treated with a transdermal nicotine patch that was changed every day. A full-thickness excisional lesion was also generated, and 14 days later, lesions had recovered. However, the Stress + Nicotine group presented a delay in wound contraction. These wounds showed a decrease in inflammatory cell infiltration and lower expression of transforming growth factor-β (TGF-β), whereas there was an increase in angiogenesis and tumor necrosis factor-α (TNF-α) expression. In vitro fibroblast migration was also impaired by the nicotine treatment of stressed-stimulated cells. In conclusion, nicotine administration potentiates the delay in wound closure observed in mice submitted to stress.

Functional interaction between human papillomavirus type 16 E6 and E7 oncoproteins and cigarette smoke components in lung epithelial cells

The smoking habit is the most important, but not a sufficient cause for lung cancer development. Several studies have reported the human papillomavirus type 16 (HPV16) presence and E6 and E7 transcripts expression in lung carcinoma cases from different geographical regions. The possible interaction between HPV infection and smoke carcinogens, however, remains unclear. In this study we address a potential cooperation between tobacco smoke and HPV16 E6 and E7 oncoproteins for alterations in proliferative and tumorigenic properties of lung epithelial cells. A549 (alveolar, tumoral) and BEAS-2B (bronchial, non-tumoral) cell lines were stably transfected with recombinant pLXSN vectors expressing HPV16 E6 and E7 oncoproteins and exposed to cigarette smoke condensate (CSC) at different concentrations. HPV16 E6 and E7 expression was associated with loss of p53 stability, telomerase (hTERT) and p16(INK4A) overexpression in BEAS-2B cells as demonstrated by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting (WB). In A549 cells we observed downregulation of p53 but not a significant increase of hTERT transcripts. In addition, the HPV16 E6/E7 transfected cell lines showed an increased proliferation rate and anchorage-independent growth in a HPV16 E6 and E7 expression-dependent manner. Moreover, both HPV16 E6/E7 and mock transfected cells showed an increased proliferation rate and anchorage-independent growth in the presence of 0.1 and 10 µg/mL CSC. However, this increase was significantly greater in HPV16 E6/E7 transfected cells (p<0.001). Data were confirmed by FCSE proliferation assay. The results obtained in this study are suggestive of a functional interaction between tobacco smoke and HPV16 E6/E7 oncoproteins for malignant transformation and tumorigenesis of lung epithelial cells. More studies are warranted in order to dissect the molecular mechanisms involved in this cooperation.