Fluoride-induced interleukin-6 and interleukin-8 synthesis in human epithelial lung cells

Efficacy of Cytoreg in the treatment of diabetic foot disease

OBJECTIVE

Complications from diabetic foot wounds, including bacterial infection, ulceration and gangrene, are major causes of hospitalisation and are responsible for 85% of amputations in patients with diabetes. Given that orally administered investigational therapeutic Cytoreg (Cytorex de Venezuela SA, Venezuela), a defined aqueous mixture of hydrofluoric, hydrochloric, sulfuric, phosphoric, citric and oxalic acids, has been shown to increase levels of arterial blood oxygen in a Wistar rat model, oral and oral+topical Cytoreg were tested on patients with diabetic foot ulcers (DFUs) under a humanitarian, compassionate-use protocol.

METHOD

All patients received oral Cytoreg (5.0 ml concentrate in fruit juice) for 30 days; half also received weekly wound washing with Cytoreg concentrate in isotonic saline (1:50 volume/volume) (oral+topical group). In addition to standard clinical observations, wounds were monitored against the Saint Elian checklist system for the diabetic foot.

RESULTS

A total of 10 patients took part in the study. Complete wound closure was observed in 4/5 patients in the oral+topical group; in the remaining patient, necrotic and fibrin tissues on the wound edges were eliminated. Half (2/4) of the patients receiving oral-only Cytoreg experienced complete wound closure; one patient in this group was removed prematurely because of an unrelated illness and was not replaced. During the study, no significant differences were observed between groups in either the oxygen saturation of the affected tissues or in insulin and glycaemia levels (p<0.05). Significant increases in arterial haemoglobin and arterial oxygen partial pressure (p<0.05) were observed, and significant decreases were measured in the levels of glycosylated haemoglobin, aspartate aminotransferase, glutamic-pyruvic transaminase, creatine and urea (p<0.05).

CONCLUSION

The results of this study justify an expanded clinical study for the treatment of DFUs with Cytoreg.

Clinical Prospective Assessment of Genotoxic and Cytotoxic Effects of Fluoride Toothpaste and Mouthwash in Buccal Mucosal Cells

Background: Fluorides are an essential component of oral hygiene products used to prevent dental decay. Therefore, a question arises about the potential harms of joint use of fluoridated toothpaste and mouthwashes regarding the increased amount of fluoride in the oral mucosa. Methods: This prospective, double-blinded parallel randomized clinical trial was conducted using a buccal micronucleus cytome assay (BMCyt assay). Forty-one participants were randomly assigned to the two groups. All participants used the same kinds of toothpaste for 12 weeks, designed explicitly for this study (non-fluoride, 1050 ppm F, and 1450 ppm F each for 4 weeks). Simultaneously, during the 3 months of the research, one group used mouthwash with fluoride (450 ppm) and another without fluoride. The buccal mucosal sampling was taken before using the tested products and after 4, 8, and 12 weeks of their use. Results: The frequency of micronuclei and the majority of other scored endpoints from the BMCyt assay showed no statistically significant differences within and between the studied groups. Comparing two groups, only statistically significant increases in the number of cells with nuclear buds (p = 0.048) and karyorrhexis (p = 0.020) at four weeks of usage were observed in the group that used mouthwash with fluoride. Conclusion: On the basis of the results, it can be concluded that simultaneous application of fluoridated toothpaste and fluoride mouthwash does not lead to cytogenetic damage in buccal mucosal cells.

Source apportionment, chemometric pattern recognition and health risk assessment of groundwater from southwestern Punjab, India

The groundwater quality of southwestern Punjab, India, is a serious cause of concern due to the presence of chemical contaminants in it. However, limited studies of groundwater quality, sources of chemical contaminants and their health risks are available for the region. Hence, this study was conducted to investigate the source, distribution and potential health risk assessment of groundwater quality in three districts of southwestern Punjab, India. The spatial distribution of groundwater chemical contaminants and their potential health risks have been illustrated using inverse distance weighting interpolation technique. The concentration of fluoride (F^-; ranged from 0.08 to 4.79 mg L^-1) exceeded the WHO limit (1.5 µg L^-1) in 80 and 50% samples collected from Bathinda and Ludhiana districts, respectively. The uranium (U) concentration ranged from 0.5 to 432 µg L^-1 and shows ~ 85%, 75% and 10% of samples collected from Bathinda, Barnala and Ludhiana districts exceeded the WHO drinking water limit (30 µg L^-1), respectively. The groundwater quality of the Bathinda district is a matter of concern due to elevated levels of alkalinity, hardness, fluoride, uranium and nitrate (NO₃^-). The principal component analysis shows close association between F^- and U, which indicates their geogenic origin. Further, they also seem to be subordinately influenced by diffuse anthropogenic activities. The clustering of Cu and Pb with NO₃^- and SO₄^2- indicates their anthropogenic origin. The non-carcinogenic health risk assessment indicates that F^-, NO₃^- and U are the major health risk pollutants in the study area. The carcinogenic health risk of As and Cr exceeded the USEPA limits (10^-6) in the entire study area, but observed to be more serious for the district Bathinda (10^-3-10^-5). The spatial distribution maps illustrate that the health risk for Bathinda district inhabitants is higher than Barnala and Ludhiana districts.

Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health

The sodium iodide symporter (NIS) is the plasma membrane glycoprotein that mediates active iodide transport in the thyroid and other tissues, such as the salivary, gastric mucosa, rectal mucosa, bronchial mucosa, placenta and mammary glands. In the thyroid, NIS mediates the uptake and accumulation of iodine and its activity is crucial for the development of the central nervous system and disease prevention. Since the discovery of NIS in 1996, research has further shown that NIS functionality and iodine transport is dependent on the activity of the sodium potassium activated adenosine 5'-triphosphatase pump (Na+, K+-ATPase). In this article, I review the molecular mechanisms by which F inhibits NIS expression and functionality which in turn contributes to impaired iodide absorption, diminished iodide-concentrating ability and iodine deficiency disorders. I discuss how NIS expression and activity is inhibited by thyroglobulin (Tg), tumour necrosis factor alpha (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin 6 (IL-6) and Interleukin 1 beta (IL-1β), interferon-γ (IFN-γ), insulin like growth factor 1 (IGF-1) and phosphoinositide 3-kinase (PI3K) and how fluoride upregulates expression and activity of these biomarkers. I further describe the crucial role of prolactin and megalin in regulation of NIS expression and iodine homeostasis and the effect of fluoride in down regulating prolactin and megalin expression. Among many other issues, I discuss the potential conflict between public health policies such as water fluoridation and its contribution to iodine deficiency, neurodevelopmental and pathological disorders. Further studies are warranted to examine these associations.

The Contribution of Fluoride to the Pathogenesis of Eye Diseases: Molecular Mechanisms and Implications for Public Health

This study provides diverse lines of evidence demonstrating that fluoride (F) exposure contributes to degenerative eye diseases by stimulating or inhibiting biological pathways associated with the pathogenesis of cataract, age-related macular degeneration and glaucoma. As elucidated in this study, F exerts this effect by inhibiting enolase, τ-crystallin, Hsp40, Na⁺, K⁺-ATPase, Nrf2, γ -GCS, HO-1 Bcl-2, FoxO1, SOD, PON-1 and glutathione activity, and upregulating NF-κB, IL-6, AGEs, HsP27 and Hsp70 expression. Moreover, F exposure leads to enhanced oxidative stress and impaired antioxidant activity. Based on the evidence presented in this study, it can be concluded that F exposure may be added to the list of identifiable risk factors associated with pathogenesis of degenerative eye diseases. The broader impact of these findings suggests that reducing F intake may lead to an overall reduction in the modifiable risk factors associated with degenerative eye diseases. Further studies are required to examine this association and determine differences in prevalence rates amongst fluoridated and non-fluoridated communities, taking into consideration other dietary sources of F such as tea. Finally, the findings of this study elucidate molecular pathways associated with F exposure that may suggest a possible association between F exposure and other inflammatory diseases. Further studies are also warranted to examine these associations.

Fluoride induced tissue hypercalcemia, IL-17 mediated inflammation and apoptosis lead to cardiomyopathy: Ultrastructural and biochemical findings

An increased prevalence of cardiac complications has been observed in residents of fluorosis endemic areas chronically exposed to fluoride. Fluoride induces soft tissue injury due to oxidative stress, lipid peroxidation (LPO) and mitochondriopathy. It was hypothesized that chronic fluoride exposure induces apoptosis in cardiomyocytes due to inflammation, lysis of extra cellular matrix and altered calcium metabolism. This study was planned to evaluate the effects of chronic fluoride exposure and the mechanism of action in the cardiac muscle. Fifteen week old male Wistar rats were administered a human equivalent dose of fluoride (50 and 100 ppm ad-libitum, HED = 5 & 10 ppm in human) for 75-days. After 75-days of fluoride exposure, the animals were euthanized and fluoride, oxidative stress (SOD, GPX, Catalase activities) and LPO were measured. Histopathological and ultrastructural pathological examinations were conducted on the cardiac tissues using light, atomic force and electron microscopies. The cardiac tissues were also assessed for apoptosis (TUNEL/Caspase assays), and tissue calcium levels (Alizarin-assay and SEM-EDX). Tissue inflammation and expression of IL-17, MMP-9, Caspase-3 and Bcl-2 were evaluated. In the fluoride exposed groups, a significant (≤0.05) increase in levels of oxidative stress, LPO and apoptosis were observed. The IL-17, MMP-9 and Caspase-3 were significantly (≤0.05) higher in the cardiac muscle after chronic fluoride exposure. The fluoride seems to have induced inflammation in the cardiac tissues, as well as an increase in tissue calcium (≤0.05). There was significant damage to cardiac muscle fibres including, thinning, distortion and neo-vasculogenesis following chronic fluoride exposure. Mitochondriopathy, lysis of ground substance, oedema, and hyper-vacuolation was seen in fluoride treated groups. Remarkable levels of distortion and bending in Z band were observed under the AFM. Many of these observed changes mimic those occurring in cardiomegaly, cardiac hypertrophy and cardiomyopathies.

Fluoride-associated ultrastructural changes and apoptosis in human renal tubule: a pilot study

The susceptibility of the kidneys to fluoride toxicity can largely be attributed to its anatomy and function. As the filtrate moves along the complex tubular structure of each nephron, it is concentrated in the proximal and distal tubules and collecting duct. It has been frequently observed that the children suffering from renal impairments also have some symptoms of dental and skeletal fluorosis. The findings suggest that fluoride somehow interferes with renal anatomy and physiology, which may lead to renal pathogenesis. The aim of this study was to evaluate the fluoride-associated nephrotoxicity. A total of 156 patients with childhood nephrotic syndrome were screened and it was observed that 32 of them had significantly high levels ( p ≤ 0.05) of fluoride in urine (4.01 ± 1.83 ppm) and serum (0.1 ± 0.013 ppm). On the basis of urinary fluoride concentration, patients were divided into two groups, namely group 1 (G-1) ( n = 32) containing normal urine fluoride (0.61 ± 0.17 ppm) and group 2 (G-2) ( n = 32) having high urine fluoride concentration (4.01 ± 1.83 ppm). Age-matched healthy subjects ( n = 33) having normal levels of urinary fluoride (0.56 ± 0.15 ppm) were included in the study as control (group 0 (G-0)). Kidney biopsies were taken from G-1 and G-2 only, who were subjected to ultrastructural (transmission electron microscopy) and apoptotic (terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling) analysis. Various subcellular ultrastructural changes including nuclear disintegration, chromosome condensation, cytoplasmic ground substance lysis, and endoplasmic reticulum blebbing were observed. Increased levels of apoptosis were observed in high fluoride group (G-2) compared to normal fluoride group (G-1). Various degrees of fluoride-associated damages to the architecture of tubular epithelia, such as cell swelling and lysis, cytoplasmic vacuolation, nuclear condensation, apoptosis, and necrosis, were observed.

Sodium fluoride induces apoptosis in cultured splenic lymphocytes from mice

Though fluorine has been shown to induce apoptosis in immune organs in vivo, there has no report on fluoride-induced apoptosis in the cultured lymphocytes. Therefore, this study was conducted with objective of investigating apoptosis induced by sodium fluoride (NaF) and the mechanism behind that in the cultured splenic lymphocytes by flow cytometry, western blot and Hoechst 33258 staining. The splenic lymphocytes were isolated from 3 weeks old male ICR mice and exposed to NaF (0, 100, 200, and 400 μmol/L) in vitro for 24 and 48 h. When compared to control group, flow cytometry assay and Hoechst 33258 staining showed that NaF induced lymphocytes apoptosis, which was promoted by decrease of mitochondria transmembrane potential, up-regulation of Bax, Bak, Fas, FasL, caspase 9, caspase 8, caspase 7, caspase 6 and caspase 3 protein expression (P < 0.05 or P <0.01), and down-regulation of Bcl-2 and Bcl-xL protein expression (P <0.05 or P <0.01). The above-mentioned data suggested that NaF-induced apoptosis in splenic lymphocytes could be mediated by mitochondrial and death receptor pathways.

Pulmonary fluorosis: a review

The increased industrialization and improvised human lifestyle lead to a surge in environmental pollution nowadays. Even the chemicals which are known as prophylactic agents were currently liable to be toxic. One among them is inorganic fluoride whose wider application in numerous processes makes it as an inevitable environmental contaminant and industrial pollutant. Although the systemic toxicity of fluoride has been extensively studied, still there is lacuna in the field of pulmonary fluoride toxicity. Hence, we have focused on the molecular mechanism of action of fluoride compounds on pulmonary system. A study of literatures that focused on the potential physiological and toxicological consequences of fluoride on pulmonary system was carried out. The goal of this review is to present an overview of the research carried out till date on the molecular aspects of fluoride exposure with emphasis on pulmonary system and their possible mechanisms.

Environmental Factors Impacting Bone-Relevant Chemokines

Chemokines play an important role in normal bone physiology and the pathophysiology of many bone diseases. The recent increased focus on the individual roles of this class of proteins in the context of bone has shown that members of the two major chemokine subfamilies-CC and CXC-support or promote the formation of new bone and the remodeling of existing bone in response to a myriad of stimuli. These chemotactic molecules are crucial in orchestrating appropriate cellular homing, osteoblastogenesis, and osteoclastogenesis during normal bone repair. Bone healing is a complex cascade of carefully regulated processes, including inflammation, progenitor cell recruitment, differentiation, and remodeling. The extensive role of chemokines in these processes and the known links between environmental contaminants and chemokine expression/activity leaves ample opportunity for disruption of bone healing by environmental factors. However, despite increased clinical awareness, the potential impact of many of these environmental factors on bone-related chemokines is still ill defined. A great deal of focus has been placed on environmental exposure to various endocrine disruptors (bisphenol A, phthalate esters, etc.), volatile organic compounds, dioxins, and heavy metals, though mainly in other tissues. Awareness of the impact of other less well-studied bone toxicants, such as fluoride, mold and fungal toxins, asbestos, and chlorine, is also reviewed. In many cases, the literature on these toxins in osteogenic models is lacking. However, research focused on their effects in other tissues and cell lines provides clues for where future resources could be best utilized. This review aims to serve as a current and exhaustive resource detailing the known links between several classes of high-interest environmental pollutants and their interaction with the chemokines relevant to bone healing.

Differential NF-κB and MAPK activation underlies fluoride- and TPA-mediated CXCL8 (IL-8) induction in lung epithelial cells

Different toxic agents have a varying potential to induce the production of the proinflammatory chemokine, CXCL8 (interleukin [IL]-8), in lung cells. A critical question is which mechanisms determine the magnitude and persistence of the CXCL8 responses to different stimuli. To approach this, we compared the potential of the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), and sodium fluoride (NaF) to induce CXCL8 responses in A549 cells, with emphasis on the importance of nuclear factor kappa B (NF-κB)- and mitogen-activated protein kinase (MAPK) signaling. Notably, TPA induced a greater release of CXCL8 than did NaF. Furthermore, TPA induced a strong, rapid, but transient upregulation of CXCL8 messenger (m)RNA, whereas NaF induced a weaker, more delayed, but persistent upregulation. With respect to signaling, TPA led to an early, strong, and relatively transient extracellular signal-regulated kinase (ERK)1/2 phosphorylation, and a less marked and even more transient phosphorylation of c-jun-N-terminal kinases (JNK1/2) and p38. In contrast, NaF elicited a lower, but relatively sustained increase in phosphorylation of ERK1/2, and a marked phosphorylation of p38 and JNK1/2, with the JNK1/2 response as most transient. Only ERK1/2 inhibition affected the TPA response, whereas inhibition of all the three MAPK cascades reduced NaF-induced CXCL8 release. TPA also induced an early, marked phosphorylation/translocation of p65 (NF-κB), whereas NaF induced slower, less pronounced effects on p65. The CXCL8 responses by TPA and NaF were reduced by p65-siRNA. In conclusion, all MAPK cascades were involved in NaF-induced CXCL8 release, whereas only ERK1/2 activation was involved in response to TPA. Furthermore, NF-κB activation appeared to be indispensable for CXCL8 induction. The early response, magnitude, and persistency of MAPK and NF-κB signaling seemed to be critical determinants for the potential to induce CXCL8. These findings underscore that a strong, rapid, and relatively transient activation of ERK1/2 in combination with NF-kB may be sufficient for a strong induction of CXCL8, which may exceed the effects of a more moderate ERK1/2 activation in combination with activation of p38, JNK1/2, and NF-κB.

Lung damage after long-term exposure of adult rats to sodium fluoride

INTRODUCTION

Fluorides, when taken in amounts exceeding the standard therapeutic dosage, are regarded as toxic substances. Chronic fluorosis causes marked destruction of lung tissues. The study aimed to determine whether the effect of a chronic toxic dose of sodium fluoride on the lung of an adult male albino rat is reversible or irreversible. This was done through light and electron microscopic studies. Morphometric study was also done.

MATERIAL AND METHODS

Forty adult male rats were used. The animals were divided into 3 groups: control group; group I (chronic fluorosis group) in which sodium fluoride was given daily for 3 months; and group II (recovery group) in which sodium fluoride was given daily for 3 months and after that the rats survived for another month.

RESULTS

The lung of group I was characterized by presence of blood and lymph congestion. Thickening of alveolar septa was also observed with rupture of septa and widening of the air spaces. The area % of collagen (1.13 ±0.5), septal wall thickness (13.47 ±6.1), and number of macrophages (5 ±2.5) increased in comparison to the control group (p ≤ 0.05). With discontinuation of sodium fluoride (group II), no much improvement was observed.

CONCLUSIONS

Chronic fluorosis has many pathological effects on the lung which are irreversible.

Dietary high fluorine induces apoptosis and alters Bcl-2, Bax, and caspase-3 protein expression in the cecal tonsil lymphocytes of broilers

Long-term excessive fluoride intake is known to be toxic and can lead to fluorosis and bone pathologies. However, the cellular mechanisms underlying sodium fluoride-induced cytotoxicity in the cecal tonsil lymphocytes are not well understood. The aims of this study were to investigate the effects of high dietary fluorine on apoptosis and the expression of the Bcl-2, Bax, and caspase-3 in the cecal tonsil lymphocytes of broilers. The broilers were fed on high-fluorine diets containing 0, 400, 800, and 1,200 mg/kg fluorine. As measured by flow cytometry, the percentage of apoptotic lymphocytes was significantly increased in the high-fluorine groups II and III when compared with those in the control group. Meanwhile, immunohistochemical tests showed that the Bcl-2 protein expression decreased, and the Bax and caspase-3 protein expression increased in the high-fluorine groups II and III. In conclusion, dietary fluorine in the range of 800-1,200 mg/kg increased lymphocyte apoptosis in the cecal tonsil of broilers, suggesting that the lymphocyte apoptosis in the cecal tonsil was mediated by direct effects of fluoride on the expression of Bcl-2, Bax, and caspase-3.

Involvement of both mitochondrial- and death receptor-dependent apoptotic pathways regulated by Bcl-2 family in sodium fluoride-induced apoptosis of the human gingival fibroblasts

Sodium fluoride (NaF) has been shown to be cytotoxic and produces inflammatory responses in humans. However, the cellular mechanisms underlying the NaF-induced cytotoxicity in periodontal tissues are unclear. This study examined whether or not NaF induces apoptosis in human gingival fibroblasts (HGF), and its underlying mechanisms by monitoring various apoptosis-associated processes. NaF reduced the cell viability of HGF in a dose- and time-dependent manner. NaF increased TUNEL-positive cell and induced apoptosis with concomitant chromatin condensation and DNA fragmentation in HGF. In addition, NaF increased the level of cytochrome c released from the mitochondria into the cytosol, enhanced the caspase-9, -8 and -3 activities, the cleavage of poly (ADP-ribose) polymerase (PARP), and up-regulated the voltage-dependent anion channel (VDAC) 1. However, NaF did not affect the production of reactive oxygen species (ROS) which is a strong apoptotic inducer. Furthermore, NaF up-regulated the Fas-ligand (Fas-L), a ligand of death receptor. Bcl-2, a member of the anti-apoptotic Bcl-2 family, was down-regulated, whereas the expression of Bax, a member of the pro-apoptotic Bcl-2 family, was unaffected in the NaF-treated HGF. These results suggest that NaF induces apoptosis in HGF through both the mitochondria-mediated pathways regulated by the Bcl-2 family and death receptor-mediated pathway.

Effects of sodium fluoride on the mechanical activity in mouse gastric preparations

The aim of the present study was to investigate the responses induced by sodium fluoride (NaF) on gastric mechanical activity, using mouse whole-stomach preparations. The mechanical activity was recorded in vitro as changes of intraluminal pressure. In most of the preparations, NaF induced a tetrodotoxin-insensitive biphasic effect characterized by early relaxation followed by slowly developing contractile response. The contraction was dependent on the concentration of NaF, whereas the relaxation was observed at only 10-30 mmol/L NaF. The contractile effect was significantly reduced by nifedipine (an L-type Ca(2+) channel blocker), ryanodine or ruthenium red (inhibitors of Ca(2+) release from sarcoplasmic reticulum), and GF109203X (a protein kinase C inhibitor). Moreover, it was abolished by neomycin (an inhibitor of phospholipase C) and potentiated by SQ22536 (an inhibitor of adenylyl cyclase). All the drugs significantly increased the relaxation, except SQ22536, which abolished it. The present results suggest that NaF causes a complex mechanical response in the whole-stomach, which might explain gastric discomfort after fluoride ingestion. The relaxation appears owing to production of cAMP, while the contractile effects imply activation of phospholipase C, protein kinase C, influx of Ca(2+), and release of Ca(2+) from ryanodine-sensitive intracellular store.

The biochemistry and physiology of metallic fluoride: action, mechanism, and implications

Fluoride is a well-known G protein activator. Activation of heterotrimeric GTP-binding proteins by fluoride requires trace amounts of Al3+ or Be2+ ions. AlFx mimics a gamma-phosphate at its transition state in a Galpha protein and is therefore able to inhibit its GTPase activity. AlFx also forms complexes with small GTP-binding proteins in the presence of their GTPase-activating proteins (GAP). As phosphate analogs, AlFx or BeFx affect the activity of a variety of phosphoryl transfer enzymes. Most of these enzymes are fundamentally important in cell signal transduction or energy metabolism. Al3+ and F- tend to form stable complexes in aqueous solution. The exact structure and concentration of AlFx depend on the pH and the amount of F- and Al3+ in the solution. Humans are exposed to both F and Al. It is possible that Al-F complexes may be formed in vivo, or formed in vitro prior to their intake by humans. Al-F complexes may play physiological or pathological roles in bone biology, fluorosis, neurotoxicity, and oral diseases such as dental caries and periodontal disease. The aim of this review is to discuss the basic chemical, biochemical, and toxicological properties of metallic fluoride, to explore its potential physiological and clinical implications.

Fluoride-induced apoptosis in human epithelial lung cells (A549 cells): role of different G protein-linked signal systems

In the present study, possible mechanisms involved in fluoride-induced apoptosis in a human epithelial lung cell line (A549) were examined. Sodium fluoride (NaF) induced apoptosis in the A549 cells, with a maximum at 5-7.5 mM after 20 hours of exposure. The number of cells with plasma membrane damage (PI-positive cells) increased moderately up to 5 mM, but markedly at 7.5 mM. Deferoxamine (an Al3+ chelator) almost completely prevented these NaF-induced responses, which may suggest a role for G protein activation. The apoptotic effect was partially reduced by the PKA inhibitor H89. NaF induced a weak but sustained increase in PKC activity, whereas the PKC activator TPA induced a transient effect. TPA, which enhanced the NaF-induced PKC activity, was not apoptotic when added alone, but facilitated the NaF-induced apoptosis and the increase in PI-positive cells. PKC downregulation induced by TPA pretreatment almost completely prevented the NaF-induced apoptosis and the increase in PI-positive cells. Pretreatment with the PKC inhibitor GF109203X, which abolished the PKC activity after 3 hours, enhanced the NaF-induced apoptosis. KN93 (a CaM kinase II inhibitor) and W7 (a calmodulin inhibitor) seem to reduce the apoptotic effect of NaF, whereas BAPTA-AM (a Ca2+ chelator) was without effect. The tyrosine kinase inhibitor genistein also markedly reduced the NaF-induced apoptosis, whereas the PI-3 kinase inhibitor wortmannin augmented the response. In conclusion, the present results suggest that NaF induces an apoptotic effect and an increase in PI-positive A549 cells via similar mechanisms, involving PKC, PKA, tyrosine kinase and Ca2+-linked enzymes, whereas PI-3 kinase seems to exert a counteracting effect.

Inhaled sodium fluoride decreases airway responsiveness to acetylcholine analogs in vivo

The study was conducted to characterize the action of NaF, which had relaxing property in carbachol precontracted isolated bovine bronchus, on airway responsiveness challenged by acetylcholine receptor agonists in rats and asthmatic humans. Tracheal flow rate and airway resistance were measured in anaesthetized rats. NaF was delivered either before carbachol challenge or together with carbachol. Patients with mild asthma were challenged with methacholine aerosol, and NaF was delivered when FEV1 fell by more than 20%. The results indicated that: (1) in rats NaF significantly inhibited carbachol-induced bronchial constriction when inhaled prior to carbachol challenge as airway resistances in the NaF and NaF+verapamil groups were significantly lower than those in the control group; (2) NaF significantly reversed carbachol or methacholine-induced bronchial constriction in asthmatic patients. In conclusion, NaF, delivered in form of aerosol, reduced bronchial responsiveness to carbachol in rats and had a bronchodilating effect on rat and human airways precontracted by inhalation of acetylcholine analogs.

Silica-induced cytokine release from A549 cells: importance of surface area versus size

Physical and chemical properties such as structure, composition and surface reactivity determine the biological activity of mineral particles. Long-term exposure to crystalline silica is known to cause persistent pulmonary inflammation leading to adverse health effects. There is less information about the potential health effects of amorphous (noncrystalline) silica. In this study, the inflammatory and cytotoxic potency of crystalline and amorphous silica in relation to particle size and surface area was assessed. Human epithelial lung cells (A549) were exposed to different size fractions of quartz ( aerodynamic diameter 0.5, 2 and 10 microm) and amorphous silica (diameter 0.3 microm). All particles induced increased release of the proinflammatory cytokines interleukin (IL)-6 and IL-8. When cells were exposed to equal masses of quartz, the smallest size fraction was the most potent. These differences, however, disappeared when cytokine release was related to equal surface areas. When amorphous silica and quartz were compared, the amorphous silica was most potent to induce IL - 6 regardless of how exposure was expressed, whereas the smallest size fraction of quartz was the most potent inducer of IL-8. Thus, the surface area seems to be the critical determinant when potency of different sizes of quartz is compared.