Nicotine treatment induces expression of matrix metalloproteinases in human osteoblastic Saos-2 cells

Fibroblast growth factor 8 (FGF8) up-regulates gelatinase expression in chondrocytes through nuclear factor-κB p65

INTRODUCTION

Gelatinases, namely MMP2 and MMP9, are involved in the natural turnover of articular cartilage, as well as the loss of the cartilage matrix in osteoarthritis (OA). Studies have reported that fibroblast growth factor 8 (FGF8) promoted the degradation of cartilage in OA. In the present study, we predicted that FGF8 promoted chondrocyte expression and secretion of gelatinases by activating NF-κB p65 signaling.

MATERIALS AND METHODS

Primary chondrocytes from C57 mice were cultured with recombinant FGF8. RNA sequencing was employed to explore the gene expression changes of gelatinases. Gelatin zymography was used to determine the activation of gelatinases. Western blot was used to investigate the expression of the gelatinases and NF-κB p65 signaling pathways, and immunofluorescence staining and NF-κB inhibitor assays were performed to confirm the activation of NF-κB p65 signaling.

RESULTS

FGF8 could increase the expression and activity of gelatinases in primary chondrocytes. And FGF8-induced expression of gelatinases was regulated through activation of NF-κB signaling with acetylated p65 accumulating in the cell nucleus. We further found that the NF-κB inhibitor, BAY 11-7082, could suppress up-regulation of gelatinase induced by FGF8.

CONCLUSION

FGF8 enhanced the expression and activity of MMP2 and MMP9 in chondrocytes via NF-κB p65 signaling.

The impact of E-cigarette vaping and vapour constituents on bone health

BACKGROUND

In contrast to cigarettes, electronic cigarette use (E-cigarettes) has grown substantially over the last decade. This is due to their promotion as both a safer alternative to cigarettes and as an aide to stop smoking. Critically, upon E-cigarette use, the user may be exposed to high doses of nicotine in addition to other compounds including flavouring chemicals, metal particulates and carbonyl compounds, particularly in highly vascularised tissues such as bone. However, there has been limited investigation into the impact of E-cigarette usage on bone physiology, particularly over extended time periods and there are no clinical recommendations regarding E-cigarette usage in relation to orthopaedic surgery. This literature review draws together data from studies that have investigated the impact of E-cigarette vapour and its major constituents on bone, detailing the models utilised and the relevant mechanistic and functional results.

MAIN BODY

Currently there is a lack of studies both in vivo and in vitro that have utilised E-cigarette vapour, necessary to account for changes in chemical composition of E-cigarette liquids upon vaping. There is however evidence that human bone and bone cells express nicotine receptors and exposure of both osteoblasts and osteoclasts to nicotine, in high concentrations may reduce their viability and impair function. Similarly, it appears that aldehydes and flavouring chemicals may also negatively impact osteoblast viability and their ability to form bone. However, such functional findings are predominantly the result of studies utilising bone cell lines such as MG-63 or Saos-2 cells, with limited use of human osteoblasts or osteoclasts. Additionally, there is limited consideration for a possible impact on mesenchymal stem cells, which can also play an import role in bone repair.

CONCLUSION

Understanding the function and mechanism of action of the various components of E-cigarette vapour in mediating human bone cell function, in addition to long term studies to determine the potential harm of chronic E-cigarette use on human bone will be important to inform users of potential risks, particularly regarding bone healing following orthopaedic surgery and injury.

Types of bone destruction and its severity in chronic periodontitis patients with tobacco smoking habit using periapical radiographs and transgingival probing: A cross-sectional study

BACKGROUND

Tobacco smoking is an independent risk factor for periodontal disease which increases periodontal pocketing, attachment loss, as well as bone loss leading to varied severity and bone destruction in the form of horizontal and vertical patterns.

AIM

The aim of the present study is to determine and measure the types and severity of bone destruction in chronic periodontitis (CP) patients with tobacco smoking habit using intraoral periapical (IOPA) radiographs and transgingival probing.

MATERIALS AND METHODS

A total of 60 male participants with CP were included in the study. Group A comprised 30 heavy cigarette smokers and Group B comprised 30 nonsmokers. Clinical parameters such as plaque index (PI), probing pocket depth (PPD), and clinical attachment loss (CAL) were recorded. Amount and pattern of bone loss were assessed using IOPA and transgingival probing.

RESULTS

The mean values of PI, PPD, and CAL were 2.50 ± 0.28 mm, 9.33 ± 1.42 mm, and 10.2 ± 1.62 mm, respectively, for cigarette smokers, which were found to be higher and statistically significant as compared to nonsmokers. Cigarette smokers showed more bone destruction than nonsmokers in respect to maxillary molars 4.42 ± 1.31 mm and incisors 3.90 ± 1.10 mm as compared to nonsmokers. Types of bone destruction were more of vertical patterns (93.3%) in cigarette smokers.

CONCLUSIONS

Tobacco smoking was associated with severe attachment loss. Tobacco smoking not only affects soft tissues but also hard tissues such as bone. Palatal sides of maxillary molars showed significantly higher bone loss and also had more percentage of vertical patterns of bone loss compared to nonsmokers. IOPA and transgingival probing may be used as noninvasive methods for the determination of types and severity of bone destruction in CP patients with or without tobacco smoking habit.

Effect of tobacco on periodontal disease and oral cancer

INTRODUCTION

Periodontal disease and oral cancer are common health hazards. Epidemiological investigations show that smoking, periodontal disease and oral cancer are closely related. Tobacco is one of the major risk factors for periodontitis and oral cancer.

METHODS

A systematic literature review was performed. To identify relevant studies, the following online databases were searched using specific keywords: PubMed, Web of Science and CNKI.

RESULTS

Tobacco not only possesses an addictive effect, but it aggravates periodontal disease by promoting the invasion of pathogenic bacteria, inhibiting autoimmune defense, aggravating the inflammatory reaction, and aggravating the loss of alveolar bone. According to current evidence, tobacco significantly aggravates the development and progression of periodontal disease and oral cancer, and periodontal disease may be related to the prevalence of oral cancer.

CONCLUSIONS

Clinicians should strongly recommend that smokers undertake a strategy to stop smoking to avoid the exacerbation of nicotine-related periodontal disease and to reduce the incidence of oral cancer.

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.

Tumor necrosis factor-α induces interleukin-34 expression through nuclear factor‑κB activation in MC3T3-E1 osteoblastic cells

Osteoblasts produce various types of cytokines under pathological conditions and control osteoclast differentiation. Tumor necrosis factor-α (TNF-α) has been demonstrated to exert complex effects in osteoblasts under local inflammatory conditions, including in periodontal and periapical diseases. Interleukin-34 (IL-34) has been recently identified as a novel regulatory factor for the differentiation and function of osteoclasts. The present study provides the first evidence, to the best of our knowledge, that the expression of IL-34 is induced by TNF-α through nuclear factor-κB (NF-κB) activation in MC3T3-E1 osteoblastic cells. TNF-α induced IL-34 expression in a dose- and time-dependent manner. Immunocytochemistry with an NF-κB antibody demonstrated that NF-κB was mainly localized in the cytoplasm of the untreated MC3T3-E1 cells. Rapid translocation of NF-κB from the cytoplasm to the nucleus was observed in the cells treated with TNF-α for 15 min. Translocation and transcriptional activity of NF-κB were also determined by western blotting and a luciferase reporter assay, respectively. Pretreatment with 100 μM CAPE, an inhibitor of NF-κB, significantly inhibited TNF-α-induced IL-34 expression. These results indicate that TNF-α induces IL-34 expression via NF-κB in osteoblasts.

ARB affects nicotine-induced gene expression profile in human coronary artery endothelial cells

AIM: To investigate the effects of nicotine and nicotine plus angiotensin II receptor blocker (ARB) on the gene expression profile of human coronary artery endothelial cells (HCAECs).

METHODS: The changes in gene expression profiles in HCAECs treated with nicotine and nicotine plus ARB olmesartan were analyzed by DNA microarray. In nicotine-treated HCAECs, 432 genes selected by P < 0.01 were greater than 1.5-fold compared with the untreated cells. Data were analyzed using IPA (Ingenuity^® Systems, www.ingenuity.com).

RESULTS: The gene expression levels of tumor necrosis factor-α, collagen type 1, matrix metalloproteinase-10, and disintegrin and metalloprotease domain 8, which are related to “cardiovascular function and disease”, were significantly increased. In canonical pathway analyses using IPA, “atherosclerosis signaling” was strongly affected by nicotine treatment and this effect was reduced by co-incubation with ARB olmesartan. These data indicate that the deleterious cardiovascular consequences of cigarette smoking may, at least in part, be due to the nicotine-induced gene expression profile related to “atherosclerosis signaling”.

CONCLUSION: The inhibitory effect of ARB against the nicotine-induced gene expression profile may possibly induce anti-atherosclerotic effects that are independent of those from lowering the blood pressure.

Nicotine affects bone resorption and suppresses the expression of cathepsin K, MMP-9 and vacuolar-type H(+)-ATPase d2 and actin organization in osteoclasts

Tobacco smoking is an important risk factor for the development of several cancers, osteoporosis, and inflammatory diseases such as periodontitis. Nicotine is one of the major components of tobacco. In previous study, we showed that nicotine inhibits mineralized nodule formation by osteoblasts, and the culture medium from osteoblasts containing nicotine and lipopolysaccharide increases osteoclast differentiation. However, the direct effect of nicotine on the differentiation and function of osteoclasts is poorly understood. Thus, we examined the direct effects of nicotine on the expression of nicotine receptors and bone resorption-related enzymes, mineral resorption, actin organization, and bone resorption using RAW264.7 cells and bone marrow cells as osteoclast precursors. Cells were cultured with 10(-5), 10(-4), or 10(-3) M nicotine and/or 50 µM α-bungarotoxin (btx), an 7 nicotine receptor antagonist, in differentiation medium containing the soluble RANKL for up 7 days. 1-5, 7, 9, and 10 nicotine receptors were expressed on RAW264.7 cells. The expression of 7 nicotine receptor was increased by the addition of nicotine. Nicotine suppressed the number of tartrate-resistant acid phosphatase positive multinuclear osteoclasts with large nuclei(≥10 nuclei), and decreased the planar area of each cell. Nicotine decreased expression of cathepsin K, MMP-9, and V-ATPase d2. Btx inhibited nicotine effects. Nicotine increased CA II expression although decreased the expression of V-ATPase d2 and the distribution of F-actin. Nicotine suppressed the planar area of resorption pit by osteoclasts, but did not affect mineral resorption. These results suggest that nicotine increased the number of osteoclasts with small nuclei, but suppressed the number of osteoclasts with large nuclei. Moreover, nicotine reduced the planar area of resorption pit by suppressing the number of osteoclasts with large nuclei, V-ATPase d2, cathepsin K and MMP-9 expression and actin organization.

The in vitro and in vivo effects of nicotine on bone, bone cells and fracture repair

INTRODUCTION

Cigarette smoke has negative effects on bone metabolism and fracture repair. However, no study has reviewed effects of nicotine on bone and fracture repair independent of other constituents of cigarette smoke. The authors review the existing evidence of the effect of nicotine on 'bone' and 'bone cells' and fracture repair, drawing conclusions relevant to clinical practice and future research.

AREAS COVERED

A literature review was conducted using PRISMA guidelines and PubMed, Cochrane, MEDLINE/OVID, EMBASE, NHS Evidence and Google scholar databases. Articles were included if they specifically investigated the effects of nicotine on 'bone' or fracture repair in animal or human models or in vitro effects on 'bone cells'. A total of 64 papers were included in this review, of which 15 were human in vitro studies and 49 animal studies wherein 9 were in vitro and 40 in vivo. In vivo studies of the effects of nicotine in animals demonstrated widespread effects on bone including osteoneogenesis, osseointegration, steady-state skeletal bone and genes and cytokines relevant to bone cell physiology and bone homeostasis. In these studies, nicotine's effects are predominately negative, inhibiting bone cell metabolism and fracture repair, whereas most in vitro studies reported biphasic responses in all bone cells except osteoclastic cells.

EXPERT OPINION

The review suggests that nicotine has effects on osteoneogenesis, osseointegration and steady-state skeletal bone in animal in vivo models, as well as effects on all 'bone cells', via several mechanisms in both animal and human cell in vitro studies. The effect of nicotine is dose-dependent, with higher concentrations having predominantly negative effects, whereas at low concentrations a stimulatory effect is seen. Stimulatory effects on certain cells may indicate a possible, limited therapeutic role; advice regarding smoking cessation perioperatively should remain due to the other harmful components of cigarette smoke, but there may be scope for allowing the use of nicotine patches instead of complete abstention. Further research into clinical outcomes is required before the exact response of bone and fracture repair in humans to nicotine is known.

Nicotine and lipopolysaccharide stimulate the production of MMPs and prostaglandin E2 by hypoxia-inducible factor-1α up-regulation in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

  Although hypoxia-inducible factor 1α (HIF-1α) is up-regulated in the periodontal pockets of periodontitis patients, the expression and precise molecular mechanisms of HIF-1α remain unknown in human periodontal ligament cells (PDLCs). The aim of this study was to explore the effects, as well as the signaling pathway, of nicotine and lipopolysaccharide (LPS) on the expression of HIF-1α and on the production of its target genes, including cyclooxygenase-2 (COX-2)-derived prostaglandin E(2) (PGE(2) ), MMP-2 and MMP-9 in PDLCs.

MATERIAL AND METHODS

  The expression of COX-2 and HIF-1α proteins was evaluated using western blotting. The production of PGE(2) and MMPs was evaluated using enzyme immunoassays and zymography, respectively.

RESULTS

  LPS and nicotine synergistically induced the production of PGE(2) , MMP-2 and MMP-9, and increased the expression of MMP-2, MMP-9, COX-2 and HIF-1α proteins. Inhibition of HIF-1α activity by chetomin or knockdown of HIF1α gene expression by small interfering RNA markedly attenuated the production of LPS- and nicotine-stimulated PGE(2) and MMPs, as well as the expression of COX-2 and HIF-1α. Furthermore, pretreatment with inhibitors of COX-2, p38, extracellular signal-regulated kinase, Jun N-terminal kinase, protein kinase C, phosphatidylinositol 3-kinase and nuclear factor-kappaB decreased the expression of nicotine- and LPS-induced HIF-1α and COX-2, as well as the activity of PGE(2) and MMPs.

CONCLUSION

  These data demonstrate novel mechanisms by which nicotine and LPS promote periodontal tissue destruction, and provide further evidence that HIF-1α is a potential target in periodontal disease associated with smoking and dental plaque.

Endoplasmic reticulum stress modulates nicotine-induced extracellular matrix degradation in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Tobacco smoking is considered to be one of the major risk factors for periodontitis. For example, about half the risk of periodontitis can be attributable to smoking in the USA. It is evident that smokers have greater bone loss, greater attachment loss and deeper periodontal pockets than nonsmoking patients. It has recently been reported that endoplasmic reticulum (ER) stress markers are upregulated in periodontitis patients; however, the direct effects of nicotine on ER stress in regard to extracellular matrix (ECM) degradation are unclear. The purpose of this study was to examine the effects of nicotine on cytotoxicity and expression of ER stress markers, selected ECM molecules and MMPs, and to identify the underlying mechanisms in human periodontal ligament cells. We also examined whether ER stress was responsible for the nicotine-induced cytotoxicity and ECM degradation.

MATERIAL AND METHODS

Cytotoxicity and cell death were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide assay and flow cytometric annexin V and propidium iodide staining. The mRNA and protein expressions of MMPs and ER markers were examined by RT-PCR and western blot analysis.

RESULTS

Treatment with nicotine reduced cell viability and increased the proportion of annexin V-negative, propidium iodide-positive cells, an indication of cell death. Nicotine induced ER stress, as evidenced by survival molecules, such as phosphorylated protein kinase-like ER-resident kinase, phosphorylated eukaryotic initiation factor-2α and glucose-regulated protein-78, and apoptotic molecules, such as CAAT/enhancer binding protein homologous protein (CHOP). Nicotine treatment led to the downregulation of ECM molecules, including collagen type I, elastin and fibronectin, and upregulation of MMPs (MMP-1, MMP-2, MMP-8 and MMP-9). Inhibition of ER stress by salubrinal and transfection of CHOP small interfering RNA attenuated the nicotine-induced cell death, ECM degradation and production of MMPs. Salubrinal and CHOP small interfering RNA inhibited the effects of nicotine on the activation of Akt, JNK and nuclear factor-κB.

CONCLUSION

These results indicate that nicotine-induced cell death is mediated by the ER stress pathway, involving ECM degradation by MMPs, in human periodontal ligament cells.

Effect of cigarette smoking on the periodontal health status: A comparative, cross sectional study

CONTEXT

Survey.

AIMS

The objective of the study was to evaluate the periodontal health status among cigarette smokers and non cigarette smokers, and oral hygiene measures.

SETTINGS AND DESIGN

Cross sectional study.

MATERIALS AND METHODS

The study included 400 male (200 cigarette smokers and 200 non smokers) aged 18-65 years. The subjects were randomly selected from the patients attending dental out-patient department of civil hospital and Himachal Dental College, Sundernagar. Community Periodontal Index (CPI) score was recorded for each patient and a questionnaire was completed by each patient.

STATISTICAL ANALYSIS USED

Chi square and t-test.

RESULTS

Periodontal condition as assessed by CPI score showed that there was statistically significant difference in the findings between cigarette smokers and non-smokers.

CONCLUSIONS

Within the limits of this study, positive association was observed between periodontal disease and cigarette smoking. It was found that cigarette smoking was associated with lesser gingival bleeding and deeper pockets as compared to non-smokers.

Influence of nicotine on the biological activity of rabbit osteoblasts

OBJECTIVES

To assess the influence of nicotine on the proliferation and gene expression of osteogenic and angiogenic mediators of osteoblasts.

MATERIAL AND METHODS

Rabbit primary osteoblasts were exposed to various concentrations of nicotine (0.001, 0.1 and 10 μmol/l). The cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The gene expression of transforming growth factor (TGF)-β(1), bone morphogenetic protein (BMP)-2, platelet-derived growth factor (PDGF)-AA and vascular endothelial growth factor (VEGF) was evaluated using real-time reverse transcription - polymerase chain reaction.

RESULTS

The osteoblast proliferation was inhibited by nicotine at the concentration of 0.001-10 μM at 48 and 72 h of culture, but with no significant effect at 24 h. The expression of TGF-β(1), BMP-2, PDGF-AA and VEGF was inhibited by nicotine at the concentrations of 0.1 and 10 μM, but with no significant difference at the low concentration of 0.001 μM.

CONCLUSIONS

Nicotine suppresses osteoblast proliferation and inhibits the expression of some key osteogenic and angiogenic mediators in the in vitro experimental model. These inhibitory effects of nicotine on the osteoblast activity may reflect, to a certain degree, the overall detrimental effects of tobacco use on the survival rate of dental implants.

The dual role of TLR3 in metastatic cell line

Toll-like receptors (TLRs) are members of transmembrane proteins that recognize conserved molecular motifs of viral and bacterial origin and initiate innate immune response. As the role of TLRs in tumors cells is still not clear, our aim was to investigate the role of TLR3 in primary tumor and metastatic cells (SW480, SW620, FaDu and Detroit 562). We have reported here on the dual role of TLR3 in pharynx metastatic cell line (Detroit 562); on one hand TLR3 activation drove cells to apoptosis while on the other its stimulation contributed to tumor progression by altering the expression of tumor promoting genes (PLAUR, RORB) and enhancing the cell migration potential. In addition, we have shown TLR3 signaling pathway is functional in another metastatic cancer cell line (SW620) suggesting TLR3 might be important in the process of tumor metastasis. Since TLR3 agonists have been used in tumor therapy with the aim to activate immune system, scientific contribution of this work is drawing attention to the importance of further work on this topic, especially pro-tumor effect of TLR3, in order to avoid possible side-effects.

Nicotinic modulation of gene expression in osteoblast cells, MG-63

Exposure to nicotine causes a broad range of biological and molecular effects on osteoblasts which are known to play a crucial role in bone metabolism and fracture healing. Most effects of nicotine on the osteoblasts are long-term adaptations at the genomic level. To identify the nicotine-regulated genes, the Agilent technologies whole human genome gene expression microarray was performed on RNA samples from osteoblast-like cells, MG-63, exposed to 100 μM nicotine. Repeat and cross-controlled microarray analyses revealed 842 genes whose expression was consistently altered at P<0.05 level following nicotine treatment. Gene ontology analysis suggested effects of nicotine on various biological and cellular processes which were associated with survival, proliferation, differentiation and apoptosis processes within the cell. Quantitative real-time reverse transcriptase PCR analysis confirmed altered expression in 7 out of 9 genes tested. The identified genes tested in the current study support our previous report that nicotine regulates the expression of genes that promote osteoblast proliferation and/or anti-apoptosis processes. Furthermore, using nicotinic acetylcholine receptor antagonists blocked the majority of the nicotine effects, indicating that these changes are dependent on nAChR activation. These results established a novel and consistent nicotinic activation of nAChR in osteoblast cells which has a broad role affecting cellular physiology through modulation of gene expression.

Non-neuronal regulation and repertoire of cholinergic receptors in organs

Many studies on the cholinergic pathway have indicated that cholinergic receptors, which are widely expressed in various cells, play an important role in all body organs. In this review, we present the concept that cholinergic responses are regulated through a neuronal or non-neuronal mechanism. The neuronal mechanism is a system in which acetylcholine binds to cholinergic receptors on target cells through the nerves. In the non-neuronal mechanism, acetylcholine, produced by neighboring cells in an autocrine/paracrine manner, binds to cholinergic receptors on target cells. Both mechanisms subsequently lead to physiological and pathophysiological responses. We also investigated the subunits/subtypes of cholinergic receptors on target cells, physiological and pathophysiological responses of the organs via cholinergic receptors, and extracellular factors that alter the subtypes/subunits of cholinergic receptors. Collectively, this concept will elucidate how cholinergic responses occur and will help us conduct further experiments to develop new therapeutic agents.

Functional role of acetylcholine and the expression of cholinergic receptors and components in osteoblasts

Recent studies have indicated that acetylcholine (ACh) plays a vital role in various tissues, while the role of ACh in bone metabolism remains unclear. Here we demonstrated that ACh induced cell proliferation and reduced alkaline phosphatase (ALP) activity via nicotinic (nAChRs) and muscarinic acetylcholine receptors (mAChRs) in osteoblasts. We detected mRNA expression of several nAChRs and mAChRs. Furthermore, we showed that cholinergic components were up-regulated and subunits/subtypes of acetylcholine receptors altered during osteoblast differentiation. To our knowledge, this is the first report demonstrating that osteoblasts express specific acetylcholine receptors and cholinergic components and that ACh plays a possible role in regulating the proliferation and differentiation of osteoblasts.

Effect of nicotine in matrix mineralization by human bone marrow and Saos-2 cells cultured on the surface of plasma-sprayed titanium implants

Smoking has an established negative impact in the clinical outcome of dental implants. This work analyses the response of human osteoblastic cells to nicotine, at the surface of plasma-sprayed commercial titanium implants. Human bone marrow (HBM) and Saos-2 cells, seeded on the surface of titanium implants and cultured in experimental conditions favoring osteoblastic differentiation, were exposed continuously to nicotine (0.0001 to 0.5 mg mL(-1)) and characterized for cell proliferation and function. Exposure of HBM cells resulted in increased cell proliferation, higher alkaline phosphatase (ALP) activity, and earlier onset of matrix mineralization at levels up to 0.2 mg mL(-1), an initial inhibitory effect in cell growth and functional activity followed by a recovery in the presence of 0.3 mg mL(-1) and a dose-dependent deleterious effect at higher levels. By contrast, exposure to nicotine did not affect cell proliferation of Saos-2 cells at levels up to 0.2 mg mL(-1), and caused only a small positive effect in ALP activity in the presence of 0.05 and 0.1 mg mL(-1); however, matrix mineralization by Saos-2 cells also occurred earlier in the cultures exposed to levels of nicotine up to 0.1 mg mL(-1). Higher concentrations caused dose-dependent inhibitory effects. Considering the high diffusion potential of nicotine, results suggest a local role of nicotine in modulating bone formation events at the implant surface.

Matrix metalloproteinases and their tissue inhibitors as prognostic indicators for diagnostic and surgical recurrence in Crohn's disease

BACKGROUND

Recurrence of disease after surgically induced remission constitutes a major and largely unpredictable problem in Crohn's disease (CD). Matrix metalloproteinases (MMP) and the tissue inhibitors of metalloproteinases (TIMP) are involved in the (etio)pathogenesis of CD and may thereby also affect postsurgical outcome. We studied the predictive value of 1) allelic composition at MMP, TIMP, and TNF-alpha single nucleotide polymorphism loci, and 2) MMP and TIMP intestinal protein levels relative to important clinical variables for recurrence of CD after resection of diseased bowel.

METHODS

From 87 CD patients with a full medical record, surgically resected tissue was homogenized and analyzed for single nucleotide polymorphism (SNP) genotype and MMP-TIMP protein levels. The prognostic value of these parameters was determined using the uni- and multivariate Cox proportional hazards analyses.

RESULTS

The T allele at TIMP-1 SNP +372 T/C was found to be associated with an increased risk for surgical recurrence. Higher levels of TIMP-1, TIMP-2, and MMP-9 in noninflamed CD tissue, but not in inflamed tissue, and negative smoking status independently protected against diagnostic and/or surgical recurrence.

CONCLUSIONS

The TIMP-1 SNP +372 T allele with an increased risk of recurrence is in line with our previous results demonstrating increased CD susceptibility and low TIMP-1 protein expression associated with this allele. High TIMP and MMP-9 levels in noninflamed tissue are predictive of a favorable disease recurrence in CD. The contribution of MMP-9 and TIMPs to disease recurrence appears not to be mediated by smoking status, since no correlation with this parameter could be demonstrated.

The I,105V polymorphism in glutathione S-transferase P1, parental smoking and the risk for nonsyndromic cleft lip with or without cleft palate

Genetic variations in the detoxification enzyme glutathione S-transferase P1 (GSTP1) may modify the teratogenicity of lifestyles, such as smoking. We investigated the role of the I105V polymorphism in GSTP1, parental periconception smoking, and their interaction with nonsyndromic cleft lip with or without cleft palate (CL/P) risk in the offspring. The GSTP1 I105V polymorphisms were determined in Dutch non-consanguineous Caucasians comprising of 155 CL/P triads (mother, father, child) and 195 control triads. The analyses were also carried out on complete triads only (n=69 CL/P and n=95 controls). Transmission disequilibrium testing and logistic regression analyses were performed. Neither maternal nor paternal smoking increased CL/P risk; odds ratios (OR): 1.2, 95 confidence intervals (CI)=0.7-2.0 and OR: 1.0, 95% CI=0.6-1.6, respectively. Carriership of the polymorphic Val105 allele in mothers may increase CL/P risk, OR: 1.5, 95% CI=0.96-2.5. Children homozygous for the Val105 allele may show an increased risk of CL/P, OR: 2.2, 95% CI=0.8-6.4. Maternal smoking tended to increase CL/P risk in mothers and children carrying Val105 alleles, OR=1.9, 95% CI=0.9-4.0 and OR=2.2, 95% CI=0.98-4.9, respectively. The highest risk for CL/P in children carrying Val105 alleles with a smoking father was 1.7, 95% CI=0.8-3.5. The GSTP1 I105V polymorphism in mothers and/or children either alone or in combination with maternal smoking may contribute to CL/P risk. Although of borderline significance, these results may underline the importance of smoking cessation in the periconception period for the prevention of CL/P in future generations.

Lipopolysaccharide enhances the production of nicotine-induced prostaglandin E2 by an increase in cyclooxygenase-2 expression in osteoblasts

Previous studies have indicated that lipopolysaccharide (LPS) from Gram-negative bacteria in plaque induces the release of prostaglandin E(2) (PGE(2)), which promotes alveolar bone resorption in periodontitis, and that tobacco smoking might be an important risk factor for the development and severity of periodontitis. We determined the effect of nicotine and LPS on alkaline phosphatase (ALPase) activity, PGE(2) production, and the expression of cyclooxygenase (COX-1, COX-2), PGE(2) receptors Ep1>4, and macrophage colony stimulating factor (M-CSF) in human osteoblastic Saos-2 cells. The cells were cultured with 10(-3) M nicotine in the presence of 0, 1, or 10 mug/ml LPS, or with LPS alone. ALPase activity decreased in cells cultured with nicotine or LPS alone, and decreased further in those cultured with both nicotine and LPS, whereas PGE(2) production significantly increased in the former and increased further in the latter. By itself, nicotine did not affect expression of COX-1, COX-2, any of the PGE(2) receptors, or M-CSF, but when both nicotine and LPS were present, expression of COX-2, Ep3, Ep4, and M-CSF increased significantly. Simultaneous addition of 10(-4) M indomethacin eliminated the effects of nicotine and LPS on ALPase activity, PGE(2) production, and M-CSF expression. Phosphorylation of protein kinase A was high in cells cultured with nicotine and LPS. These results suggest that LPS enhances the production of nicotine-induced PGE(2) by an increase in COX-2 expression in osteoblasts, that nicotine-LPS-induced PGE2 interacts with the osteoblast Ep4 receptor primarily in autocrine or paracrine mode, and that the nicotine-LPS-induced PGE(2) then decreases ALPase activity and increases M-CSF expression.