A new method for isolation of salivary neutrophils and determination of their functional activity

OMIP-100: A flow cytometry panel to investigate human neutrophil subsets

This 14-color, 13-antibody optimized multicolor immunofluorescence panel (OMIP) was designed for deep profiling of neutrophil subsets in various types of human samples to contextualize neutrophil plasticity in a range of healthy and diseased states. Markers present in the OMIP allow the profiling of neutrophil subsets associated with ontogeny, migration, phagocytosis capacity, granule release, and immune modulation. For panel design, we ensured that the commonly available fluorophores FITC/AF488, PE, and APC were assigned to the intracellular subset marker Olfactomedin 4, the maturity and activation marker CD10, and whole blood subset marker CD177, respectively. These markers can be easily replaced without affecting the core identification of neutrophils, enabling antibodies to new neutrophil antigens of interest or for fluorescent substrates to assess different neutrophil functions to be easily explored. Panel optimization was performed on whole blood and purified neutrophils. We demonstrate applications on clinical samples (whole blood and saliva) and experimental endpoints (purified neutrophils stimulated through an in vitro transmigration assay). We hope that providing a uniform platform to analyze neutrophil plasticity in various sample types will facilitate the future understanding of neutrophil subsets in health and disease.

Desquamated Epithelial Cells of Unstimulated Human Whole Saliva Express Both EGF Transcript and Protein

Objective

The aim of this study was to investigate if desquamated oral epithelial cells (DOECs) express the epidermal growth factor (EGF) and if these cells thereby may contribute to salivary EGF contents.

Background

DOECs have recently been shown to harbor the antimicrobial peptide LL-37, proposing that they may also store other biologically important salivary peptides/proteins. The EGF peptide is a growth factor which plays a critical role to maintain epithelial integrity and promote epithelial healing. The EGF is produced by salivary glands, but it is not known whether DOECs contain the EGF and thereby contribute to salivary EGF levels.

Materials and Methods

DOECs were isolated from unstimulated whole saliva collected from four healthy volunteers. EGF protein expression was determined in cell lysates by dot blot and ELISA. Cellular distribution of cytokeratin, the proliferation marker Ki67, and EGF immunoreactivity were assessed by immunocytochemistry. EGF gene expression was investigated by qPCR. Expression of EGF transcript and protein in DOECs was compared to that in the human cultured keratinocyte cell line (HaCaT) cells.

Results

EGF protein expression was detected in DOEC cell lysates by both dot blot and ELISA. Strong cytoplasmic EGF immunoreactivity was observed in DOECs, although some cells showed only a weak immunoreactive signal for EGF. Moreover, DOECs, besides containing EGF protein, also expressed transcript for EGF. Interestingly, ELISA analysis revealed that EGF protein contents were higher in DOECs than in HaCaT cells. ELISA analysis also disclosed that EGF concentration was about 10 times higher in whole saliva compared to DOECs. EGF transcript expression was about 50% lower in HaCaT cells stimulated with high (10%) compared to low (0.1%) concentration of fetal bovine serum, representing growth-stimulated and growth-restricted conditions, respectively, implying that growth-stimulus exerts negative feedback on EGF gene activity in HaCaT cells.

Conclusion

Here, we show for the first time that DOECs express the EGF, arguing that these cells contribute to salivary EGF contents and hence may play a role in gingival epithelial repair and wound healing.

Salivary neutrophil sampling feasibility in general population for gene expression analysis

OBJECTIVE

Human gene expression studies typically rely on peripheral blood samples as a cellular source, however there are numerous situations in which venipuncture is contraindicated. To this end, an oral rinse-based method for collecting salivary neutrophils as a cellular source for gene expression analyses was previously developed and shown in a pilot study with five male participants to yield mRNA expression results comparable to those obtained from peripheral blood samples. The objective of the current study was to characterize the generalizability of the oral rinse-based method by analyzing unpublished RNA quality data obtained through a parent study that collected salivary neutrophil samples using the method from a larger sample size and including both men and women.

RESULTS

The 260/280 nm absorbance ratios of the RNA obtained from 48 participants using the oral rinse-based method were within the expected range (average = 1.88 ± 0.16) for the majority of the samples, and no significant differences in RNA quality were found between participants' health, age group, or gender. Together with published data confirming the integrity of RNA obtained using the same method, these results support the feasibility of using this noninvasive method for obtaining samples for human gene expression analyses.

Selective neutrophil activation via a programmable stopped-flow injection approach: Multiple evidences of priming state of salivary polymorphonuclear neutrophils compared to circulatory polymorphonuclear neutrophils

Activated polymorphonuclear neutrophils play an important role in host defense system against invading pathogens via releasing reactive oxygen species through respiratory bursts. Nowadays, neutrophil activation process has been found to be modeled as a two-stages continuum from dormant to primed, and to fully activated. Although the differences of salivary and circulatory neutrophils have been investigated in various experimental designs, priming state of salivary polymorphonuclear neutrophils with respiratory burst has not been comprehensively studied. Here, for the first time so far, a programmable flow injection analysis based on Stop in Flow Cell operation mode has been applied to batch analyzing comparative study of neutrophil activation. The high-sensitivity luminol-dependent chemiluminescence assay has been employed with just 330 μL of cell suspension consumption per sample, and the process has been conducted rapidly and efficiently within 15 min to keep the neutrophils viability. ROS from either unstimulated or substimulated or stimulated salivary polymorphonuclear neutrophils, in comparison with those from autologous circulatory polymorphonuclear neutrophils, have been determined, together with further monitoring the impact of extracellular and intracellular calcium ion (Ca²⁺) on neutrophils ROS generation. Conclusively, the priming state of salivary polymorphonuclear neutrophils during activation has been testified from multiple aspects.

Oral Neutrophils: Underestimated Players in Oral Cancer

The composition of the oral milieu reflects oral health. Saliva provides an environment for multiple microorganisms, and contains soluble factors and immune cells. Neutrophils, which rapidly react on the changes in the microenvironment, are a major immune cell population in saliva and thus may serve as a biomarker for oral pathologies. This review focuses on salivary neutrophils in the oral cavity, their phenotype changes in physiological and pathological conditions, as well as on factors regulating oral neutrophil amount, activation and functionality, with special emphasis on oral cancer and its risk factors.

Neutrophil phenotypes in health and disease

Neutrophils are one of the most important effector cells of the innate immune response (1). They are traditionally seen as a homogenous population of short-lived cells mainly involved in the defence against extracellular microorganisms by phagocytosis and intracellular killing (1,2). The cells contain a large armamentarium that aids in this function and ranges from the production of reactive oxygen species by a membrane-bound NADPH oxidase to cytotoxic proteins and peptides residing in the different granules present in the cytoplasm (3). Recently, the view of neutrophils belonging to a homogenous population of cells has been challenged, and several neutrophil phenotypes have been described that exhibit specialized functions, such as involvement in tissue repair, tumour killing and immune regulation (4). It is not clear whether these cells belong to separate parallel lineages originating from the bone marrow or that neutrophils become instructed in the distant tissues, thus changing their phenotypes. In addition, functional heterogeneity in a phenotypically homogenous population of neutrophils adds to the complexity of neutrophil phenotypes(5). This article will review the current literature describing the heterogeneity within the neutrophil compartment with respect to both phenotype and function in health and disease.

Polymorphonuclear neutrophil integrity and functionality are preserved when exposed to saliva

OBJECTIVE

Polymorphonuclear neutrophils (PMNs) are the most abundant innate immune cells and are also important effectors in the maintenance of oral health. However, little is known about the effects of saliva on the PMN. We therefore aimed to investigate the effect of saliva on the PMNs' morphology and functioning.

DESIGN

Effect of saliva on the membrane integrity of PMNs isolated from blood was evaluated with FACS using Annexin V (apoptosis marker) and propidum iodide (membrane integrity marker). The effect on cell morphology was examined using transmission electron imaging. Binding and phagocytosis of the oral bacterium Fusobacterium nucleatum by PMNs was analysed by FACS. Reactive oxygen species (ROS) production was measured with chemiluminescence.

RESULTS

Incubation with saliva for 60 min had no detectable effects on the membrane integrity or the morphology of PMNs. In contrast, preincubation of F. nucleatum with saliva inhibited its subsequent interaction with PMNs, resulting in a diminished production of ROS.

CONCLUSIONS

Saliva does not impair the function of PMNs. However, interaction of salivary components with F. nucleatum may affect their recognition by PMNs resulting in a diminished functional response.

Impaired polymorphonuclear neutrophils in the oral cavity of edentulous individuals

Oral health is characterized by functional oral polymorphonuclear neutrophils (oPMNs). Edentulism might be associated with a loss of oPMNs because these cells enter the oral cavity primarily through the gingival crevices. The main aim of this study was to investigate the numbers of oPMNs in rinse samples obtained from edentulous (n = 21) and dentate (n = 20) subjects. A second study aim was to investigate possible differences between oPMNs and peripheral blood polymorphonuclear neutrophils (cPMNs). Apoptosis/necrosis and cell-activation markers (CD11b, CD63 and CD66b) were analyzed using flow cytometry. Reactive oxygen species (ROS) production was determined either without stimulation (constitutive) or in response to 10 μM phorbol myristate acetate or Fusobacterium nucleatum. The edentulous subjects presented with lower oPMN counts and higher percentages of apoptotic/necrotic oPMNs compared with dentate subjects. Furthermore, oPMNs from edentulous donors expressed low levels of all three activation markers and low constitutive ROS. In contrast, oPMNs from dentate subjects expressed high levels of all three activation markers and a higher level of constitutive ROS than cPMNs. When challenged, oPMNs from edentulous subjects showed no upregulation in ROS production, whereas oPMNs from dentate subjects retained their ability to respond to stimulation. The functional characteristics of cPMNs were comparable between edentulous and dentate subjects. This study demonstrates that despite having functional cPMNs, edentulous subjects have low oPMN numbers that are functionally impaired.

Characterization of the CD177 interaction with the ANCA antigen proteinase 3

Proteinase 3 is a serine protease found in neutrophil granules and on the extracellular neutrophil membrane (mPR3). mPR3 is a major antigen for anti-neutrophil cytoplasmic antibodies (PR3-ANCAs), autoantibodies causing fatal autoimmune diseases. In most individuals, a subpopulation of neutrophils also produce CD177, proposed to present additional PR3 on the surface, resulting in CD177^neg/mPR3^low and CD177^pos/mPR3^high neutrophil subsets. A positive correlation has been shown between mPR3 abundance, disease incidence, and clinical outcome. We present here a detailed investigation of the PR3:CD177 complex, verifying the interaction, demonstrating the effect of binding on PR3 proteolytic activity and explaining the accessibility of major PR3-ANCA epitopes. We observed high affinity PR3:CD177 complex formation by surface plasmon resonance. Using flow cytometry and a PR3-specific FRET assay, we found that CD177 binding reduced the proteolytic activity of PR3 in vitro using purified proteins, in neutrophil degranulation supernatants containing wtPR3 and directly on mPR3^high neutrophils and PR3-loaded HEK cells. Finally, CD177^pos/mPR3^high neutrophils showed no migration advantage in vitro or in vivo when migrating from the blood into the oral cavity. We illuminate details of the PR3:CD177 interaction explaining mPR3 membrane orientation and proteolytic activity with relevance to ANCA activation of the distinct mPR3 neutrophil populations.

Oral polymorphonuclear neutrophil characteristics in relation to oral health: a cross-sectional, observational clinical study

Polymorphonuclear neutrophils (PMNs) have a major role in the innate immune system. However, little is known about PMN contribution in relation to oral health. The objective of this study was to investigate the numbers and functional characteristics of oral PMNs (oPMNs) compared with circulatory PMNs (cPMNs). Oral rinse and venous blood samples were obtained from 268 systemically and orally healthy volunteers in a cross-sectional observational study. PMN counts, cell cycle analysis and cellular activation state were investigated. Also, reactive oxygen species (ROS) production was analyzed, with and without bacterial stimulation (Fusobacterium nucleatum). In males, 1.2 × 10⁶±1.0 × 10⁶ oPMNs were collected, and showed a tendency to correlate with the levels of gingival bleeding (r=0.215, P=0.008). Comparable oPMNs counts were found among females (1.0 × 10⁶±0.7 × 10⁶). More late-stage apoptotic/necrotic cells were found among the oPMNs (53.1%) compared with the cPMNs (8.5% P<0.001). Without additional stimulation, oPMNs were more activated than cPMNs, as indicated by higher expression of CD11b, CD63 and CD66b, and higher constitutive ROS levels (P<0.001). Notably, in response to bacterial stimulation, oPMNs released comparable ROS levels as cPMNs (P=0.042). In conclusion, this study provides data on viable oPMNs showing high levels of activation in orally and systemically healthy individuals, free of apparent caries lesions and periodontal disease. These data suggests that although the oPMNs are in a more mature stage of their life cycle compared with the cPMNs, oPMNs are still responsive to stimulation, which indicates their functional potential and possible contribution to a healthy oral ecosystem.

Dynamic interactions of neutrophils and biofilms

BACKGROUND

The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms.

OBJECTIVE/DESIGN

In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed.

RESULTS/CONCLUSION

Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

Oral neutrophils are an independent marker of the systemic inflammatory response after cardiac bypass

Background

Cardiopulmonary bypass (CPB) is an immuno-reactive state where neutrophils are activated and accumulate in different tissues. Edema and tissue necrosis are the most common sequelae observed, predominantly in the lungs, kidneys, and heart, heralding significant risk for postoperative complications. No method exists to noninvasively assess in vivo neutrophil activity. The objective of this study was to determine if neutrophil recruitment to the oral cavity would correlate with specific biomarkers after coronary bypass surgery (CPB).

Methods

We conducted a single site prospective observational study including non-consecutive adult patients undergoing elective, on-pump CPB. Blood and either oral cavity rinses or swabs were collected pre- and post-CPB. Absolute neutrophil counts from oral samples and serum biomarkers were measured. The association between neutrophil recruitment to the oral cavity, biomarkers and outcomes after CPB were analyzed.

Results

CPB was associated with statistically significant increases in oral and blood neutrophil counts, as well as an increase in certain biomarkers over preoperative baseline. Peripheral blood neutrophil count were increased at all time points however statistically significant differences in median oral neutrophil counts were observed only at the time point immediately postoperative, and in what seems to be two unique patient populations (p < 0.001; group 1, median: 1.6×10⁵, Interquartile range [IQR], 1.1×10⁵ - 4.8×10⁵, and group 2, median: 1.9×10⁶, IQR, 8.7×10⁵ - 4.0×10⁶).

Conclusions

CPB is associated with a transient increase in oral neutrophils that may correlate with the systemic inflammatory response; oral neutrophils may have the ability to discriminate and identify unique patient populations based on their tissue migration.

Noninvasive measurement of smoking-associated N(3)-ethyladenine and N(7)-ethylguanine in human salivary DNA by stable isotope dilution nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry

Evidence showed that ethylating agents are contained in cigarette smoke, which damage DNA producing ethylated DNA adducts, including N(3)-ethyladenine (3-EtAde) and N(7)-ethylguanine (7-EtGua). These two ethylpurines can be depurinated spontaneously and be repaired by enzymes and they have been detected in human urine. In this study, a highly specific and sensitive assay based on stable isotope dilution nanoflow liquid chromatography nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS) was used to measure 3-EtAde and 7-EtGua in human salivary DNA. These ethylpurines were released from DNA by neutral thermal hydrolysis and then enriched by a solid-phase extraction column before nanoLC-NSI/MS/MS analysis. The detection limits (S/N≥3) of 3-EtA and 7-EtG were 15 fg (92 amol) and 10 fg (56 amol), respectively, injected on-column. The lower quantification limits of 3-EtAde and 7-EtGua were both 100 fg, i.e. 620 and 560 amol, respectively, corresponding to 9.4 and 8.6 adducts in 10(9) normal nucleotides, respectively, starting with as little as 20 μg of DNA isolated from an average of 3 mL of saliva. The mean (±SD) levels of 3-EtAde in 15 smokers and 15 nonsmokers were 12.6±7.0 and 9.7±5.3 in 10(8) normal nucleotides, respectively, while those of 7-EtGua were 14.1±8.2 and 3.8±2.8 in 10(8) normal nucleotides in smokers and nonsmokers, respectively. Levels of 7-EtGua, but not 3-EtAde, were statistically significantly higher in smokers than in nonsmokers (p<0.0001). Furthermore, salivary 7-EtGua levels are significantly correlated with the number of cigarettes smoked per day as well as with the smoking index. This highly specific and sensitive stable isotope dilution nanoLC-NSI/MS/MS assay might be feasible in measuring 7-EtGua in human salivary DNA as a noninvasive biomarker for DNA damage induced by cigarette smoking.

Detection and simultaneous quantification of three smoking-related ethylthymidine adducts in human salivary DNA by liquid chromatography tandem mass spectrometry

Smoking cigarette increases levels of certain ethylated DNA adducts in certain tissues and urine. Cigarette smoking is a major risk factor of various cancers and DNA ethylation is involved in smoking-related carcinogenesis. Among the ethylated DNA adducts, O(2)-ethylthymidine (O(2)-edT) and the promutagenic O(4)-ethylthymidine (O(4)-edT) are poorly repaired and they can accumulate in vivo. Using an accurate, highly sensitive, and quantitative assay based on stable isotope dilution nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS), O(2)-edT, N(3)-edT (N(3)-ethylthymidine), and O(4)-edT adducts in human salivary DNA were simultaneous detected and quantified. Saliva is easily accessible and available and it can be a potential target in searching for noninvasive biomarkers. Under the highly selected reaction monitoring (H-SRM) mode, salivary samples from 20 smokers and 13 nonsmokers were analyzed. Starting with 50 μg of DNA isolated from about 3.5 mL of saliva, levels of O(2)-edT, N(3)-edT, and O(4)-edT in 20 smokers' salivary DNA samples were 5.3±6.2, 4.5±5.7, 4.2±8.0 in 10(8) normal nucleotides, respectively, while those in 13 nonsmokers were non-detectable. In addition, statistically significant correlations (p<0.0001) were observed between levels of O(2)-edT and N(3)-edT (γ=0.7388), between levels of O(2)-edT and O(4)-edT (γ=0.8839), and between levels of N(3)-edT, and O(4)-edT (γ=0.7835). To the best of our knowledge, this is the first report of detection and quantification of these three ethylthymidine adducts in human salivary DNA, which might be potential biomarkers for exposure to ethylating agents and possibly for cancer risk assessment.

Oral neutrophils display a site-specific phenotype characterized by expression of T-cell receptors

BACKGROUND

Neutrophils, key cells of the innate immune system, were previously thought to be terminally differentiated cells, incapable of altering their gene expression after differentiation and maturation in the bone marrow. Only recently has it been shown that neutrophils perform rapid and complex changes in gene expression during inflammatory responses. Previous work by the authors has demonstrated differences in reactive oxygen species production between oral and peripheral blood neutrophils isolated from patients with chronic periodontitis, suggesting that oral neutrophils present with a unique oral phenotype. Understanding differences in the neutrophil transcriptome after transit from circulation into the site of inflammation will give new insights into how these innate immune cells function during inflammation.

METHODS

Venous blood and oral rinse samples were obtained from five healthy participants. Blood neutrophils were isolated using a standard gradient method. Oral neutrophils were isolated through nylon mesh filters of different pore sizes (40 to 10 μm). RNA was purified from isolated neutrophils, and gene expression microarray analysis was completed. Results were confirmed by quantitative reverse transcription-polymerase chain reaction and immunofluorescence microscopy.

RESULTS

Oral neutrophil isolation, which is critical when analyzing gene expression with samples clear of epithelial cell contamination, was optimized. It was also demonstrated that oral neutrophils present with a significant increase in T-cell receptor expression compared with circulating neutrophils, suggesting a role for oral neutrophils in crosstalk between the innate and adaptive immune system in the mouth.

CONCLUSION

To the best of the authors' knowledge, it is demonstrated for the first time that, compared with circulating neutrophils, oral neutrophils present a site-specific gene expression profile in healthy individuals.

Isolation of human and mouse neutrophils ex vivo and in vitro

Neutrophils are one of main cellular elements of innate immune system that act as the first line of host defense against invasion by microorganisms. Neutrophils phagocytose and kill microbes through production of toxins such as hydrogen peroxide, superoxide anion, and nitric oxide. Recent studies have demonstrated a new strategy-so-called neutrophil extracellular traps (NETs) that are able to kill bacteria and fungi in vivo and in vitro (Brinkmann et al., Science 303:1532-1535, 2004; Wartha and Henriques-Normark, Sci Signal 1:pe25, 2008). Neutrophils are, therefore, always a major focus of investigation for scientists all over the world. Isolation of neutrophils from either human beings or animals such as mice is a very common first step for researchers to start their investigations on innate immunity to microbes. Fortunately, there are nowadays many methods available to obtain neutrophils from peripheral blood, bone marrow, and cell cultures. However, researchers still encounter technical problems in terms of purification, viability, and recovery. In this chapter, different approaches to the methodology of the isolation of neutrophils are described.

Quantitative analysis of multiple exocyclic DNA adducts in human salivary DNA by stable isotope dilution nanoflow liquid chromatography-nanospray ionization tandem mass spectrometry

Exocyclic DNA adducts, including 1,N(2)-propano-2'-deoxyguanosine derived from acrolein (AdG) and crotonaldehyde (CdG) and the three lipid peroxidation-related etheno adducts 1,N(6)-etheno-2'-deoxyadenosine (εdAdo), 3,N(4)-etheno-2'-deoxycytidine (εdCyt), and 1,N(2)-etheno-2'-deoxyguanosine (1,N(2)-εdGuo), play an important role in cancer formation and they are associated with oxidative-stress-induced DNA damage. Saliva is an easily accessible and available biological fluid and a potential target of noninvasive biomarkers. In this study, a highly sensitive and specific assay based on isotope dilution nanoflow LC-nanospray ionization tandem mass spectrometry (nanoLC-NSI/MS/MS) is developed for simultaneous detection and quantification of these five adducts in human salivary DNA. The levels of AdG, CdG, εdAdo, εdCyd, and 1,N(2)-εdGuo, measured in 27 human salivary DNA samples from healthy volunteers, were determined as 104 ± 50, 7.6 ± 12, 99 ± 50, 72 ± 49, 391 ± 198 (mean ± SD) in 10(8) normal nucleotides, respectively, starting with 25 μg of DNA isolated from an average of 3 mL of saliva. Statistically significant correlations were found between levels of εdAdo and εdCyd (γ = 0.8007, p < 0.0001), between levels of εdAdo and 1,N(2)-εdGuo (γ = 0.6778, p = 0.0001), between levels of εdCyd and 1,N(2)-εdGuo (γ = 0.5643, p = 0.0022), between levels of AdG and 1,N(2)-εdGuo (γ = 0.5756, p = 0.0017), and between levels of AdG and εdAdo (γ = 0.3969, p = 0.0404). Only 5 μg of DNA sample was analyzed for simultaneous quantification of these adducts. The easy accessibility and availability of saliva and the requirement for the small amount of DNA samples make this nanoLC-NSI/MS/MS assay clinically feasible in assessing the possibility of measuring 1,N(2)-propano-2'-deoxyguanosine and etheno adducts levels in human salivary DNA as noninvasive biomarkers for DNA damage resulting from oxidative stress and for evaluating their roles in cancer formation and prevention.

Metabolism and biomarkers of heterocyclic aromatic amines in molecular epidemiology studies: lessons learned from aromatic amines

Aromatic amines and heterocyclic aromatic amines (HAAs) are structurally related classes of carcinogens that are formed during the combustion of tobacco or during the high-temperature cooking of meats. Both classes of procarcinogens undergo metabolic activation by N-hydroxylation of the exocyclic amine group to produce a common proposed intermediate, the arylnitrenium ion, which is the critical metabolite implicated in toxicity and DNA damage. However, the biochemistry and chemical properties of these compounds are distinct, and different biomarkers of aromatic amines and HAAs have been developed for human biomonitoring studies. Hemoglobin adducts have been extensively used as biomarkers to monitor occupational and environmental exposures to a number of aromatic amines; however, HAAs do not form hemoglobin adducts at appreciable levels, and other biomarkers have been sought. A number of epidemiologic studies that have investigated dietary consumption of well-done meat in relation to various tumor sites reported a positive association between cancer risk and well-done meat consumption, although some studies have shown no associations between well-done meat and cancer risk. A major limiting factor in most epidemiological studies is the uncertainty in quantitative estimates of chronic exposure to HAAs, and thus, the association of HAAs formed in cooked meat and cancer risk has been difficult to establish. There is a critical need to establish long-term biomarkers of HAAs that can be implemented in molecular epidemioIogy studies. In this review, we highlight and contrast the biochemistry of several prototypical carcinogenic aromatic amines and HAAs to which humans are chronically exposed. The biochemical properties and the impact of polymorphisms of the major xenobiotic-metabolizing enzymes on the biological effects of these chemicals are examined. Lastly, the analytical approaches that have been successfully employed to biomonitor aromatic amines and HAAs, and emerging biomarkers of HAAs that may be implemented in molecular epidemiology studies are discussed.

Identification of carcinogen DNA adducts in human saliva by linear quadrupole ion trap/multistage tandem mass spectrometry

DNA adducts of carcinogens derived from tobacco smoke and cooked meat were identified by liquid chromatography-electrospray ionization/multistage tandem mass spectrometry (LC-ESI/MS/MS(n)) in saliva samples from 37 human volunteers on unrestricted diets. The N-(deoxyguanosin-8-yl) (dG-C8) adducts of the heterocyclic aromatic amines 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole (AalphaC), 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx), and the aromatic amine, 4-aminobiphenyl (4-ABP), were characterized and quantified by LC-ESI/MS/MS(n), employing consecutive reaction monitoring at the MS(3) scan stage mode with a linear quadrupole ion trap (LIT) mass spectrometer (MS). DNA adducts of PhIP were found most frequently: dG-C8-PhIP was detected in saliva samples from 13 of 29 ever-smokers and in saliva samples from 2 of 8 never-smokers. dG-C8-AalphaC and dG-C8-MeIQx were identified solely in saliva samples of three current smokers, and dG-C8-4-ABP was detected in saliva from two current smokers. The levels of these different adducts ranged from 1 to 9 adducts per 10(8) DNA bases. These findings demonstrate that PhIP is a significant DNA-damaging agent in humans. Saliva appears to be a promising biological fluid in which to assay DNA adducts of tobacco and dietary carcinogens by selective LIT MS techniques.

Refractory periodontitis population characterized by a hyperactive oral neutrophil phenotype

BACKGROUND

Neutrophils, in addition to being the primary protective component of the innate immune system, also contribute to periodontal destruction through production of reactive oxygen species (ROS), which cause damage to connective tissues and extracellular matrix after neutrophil activation. We have previously shown that hyperactive neutrophils are present in peripheral blood samples of patients diagnosed with refractory periodontitis. To test the hypothesis that oral neutrophil hyperactivity is related to periodontal disease severity, we used a flow cytometric approach to isolate and analyze oral neutrophil ROS (oROS) production in a refractory periodontal disease patient population.

METHODS

Oral rinse samples and venous blood were obtained from 13 patients diagnosed with refractory periodontitis. After isolation of neutrophils from both samples, dihydrorhodamine 123 was used as a fluorescent probe for phorbol 12-myristate 13-acetate-mediated ROS production as assessed through flow cytometry. For each patient, oROS production levels were expressed as a percentage of their baseline to maximal peripheral blood neutrophil ROS production range.

RESULTS

Two distinct groups of refractory patients were identified based on levels of phorbol 12-myristate 13-acetate-stimulated oROS production. The patient group with high oROS production had significantly more clinical attachment loss (AL) compared to the patient group with low oROS production.

CONCLUSIONS

Our findings demonstrate that a group of refractory patients with increased clinical AL present a hyperactive oral neutrophil phenotype characterized by increased potential for ROS production. Identification of this exaggerated oral neutrophil phenotype could allow clinicians to identify which patients are more susceptible to rapid disease progression.

Comparison of superoxide detection abilities of newly developed spin traps in the living cells

This study compared the superoxide detection abilities of four spin traps, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO), 5-(diphenylphosphinoyl)-5-methyl-1pyrroline N-oxide (DPPMPO) and 5-(2,2-dimethyl-1,3-propoxy cyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO) in living cells. Electron spin resonance (ESR) signals of the superoxide adducts were observed when spin traps were added to a suspension of human oral polymorphonuclear leukocytes (OPMNs) stimulated by phorbol 12-myristate 13-acetate. The ESR signal of the CYPMPO-superoxide adduct (CYPMPO-OOH) increased for 24 min after the initiation of the reaction, whereas the signals from DMPO-OOH and DPPMPO-OOH peaked at 6 and 10 min, respectively. The maximum concentrations of DMPO-OOH, DPPMPO-OOH and CYPMPO-OOH in OPMNs were 1.9, 6.0 and 10.7 microM, respectively. Furthermore, CYPMPO could more efficiently trap superoxide in blood PMNs compared with DEPMPO. From these results, it was concluded that CYPMPO performs better than DMPO, DPPMPO and DEPMPO for superoxide measurements in living cell systems because it has lower cytotoxicity and its superoxide adduct has a longer lifetime.

A hyperactive neutrophil phenotype in patients with refractory periodontitis

BACKGROUND

Neutrophils (PMNs) are critical components of the innate immune system and help to maintain oral health in the face of a constant bacterial challenge. However, along with protecting the periodontium from microbial invasion, these cells release potent lysosomal enzymes and oxygen radicals that can be destructive to periodontal tissues and lead to tooth loss. We examined neutrophil function in a unique population of patients diagnosed with refractory aggressive periodontitis (RAP).

METHODS

Venous blood was obtained from 12 non-smoking patients who had been diagnosed with RAP, 10 patients with chronic periodontitis who had responded to periodontal therapy (CP), and 13 periodontally healthy controls (HCs). Peripheral blood PMNs were loaded with dihydrorhodamine 123 and stimulated with phorbol 12-myristate 13-acetate (PMA) to measure the receptor-independent respiratory burst of these key immune cells. Phagocytosis via the complement and Fc-gamma receptors was also assessed.

RESULTS

PMNs from patients with RAP displayed significantly increased PMA-induced oxygen radical production compared to those from the HC and CP patients. PMNs from RAP patients also displayed increased phagocytosis compared to those from the CP group.

CONCLUSIONS

Our findings demonstrated a larger receptor-independent respiratory burst and higher phagocytotic activity in PMNs derived from patients with RAP compared to PMNs derived from CP patients and periodontally HCs. We speculate that the higher intrinsic intracellular activity of the nicotinamide adenine dinucleotide phosphate oxidase system may account for the continued periodontal breakdown, despite ongoing periodontal therapy in these challenging patients.

Areca nut extracts reduce the intracellular reactive oxygen species and release of myeloperoxidase by human polymorphonuclear leukocytes

BACKGROUND AND OBJECTIVE

Polymorphonuclear leukocytes (PMN) represent the first line of host defense. Areca nut extract inhibits the bactericidal activity of, and the release of superoxide anion (O2- ) by, PMN. This study investigated the effects of areca nut extract on the intracellular production of reactive oxygen species (ROS) and on the extracellular release of lysosomal enzyme, myeloperoxidase (MPO), by PMN. The effects of arecoline, a principal component of areca nut, were also examined.

MATERIAL AND METHODS

Human PMN were treated with various concentrations of areca nut extract or arecoline followed by treatment with Hanks' balanced salt solution, with or without cytochalasin B and fMet-Leu-Phe (CB/fMLP). The viability of PMN was determined using propidium iodide staining and flow cytometry. The presence of intracellular ROS was determined using 2',7'-dichlorofluorescin diacetate and fluorometry. MPO release was determined using a substrate assay.

RESULTS

Areca nut extract (25 and 50 microg/ml) significantly decreased the viability of PMN. The intracellular levels of ROS and the extracellular release of MPO were induced in PMN by CB/fMLP. Exposure of PMN to areca nut extract (up to 25 microg/ml) or to arecoline (up to 2 mg/ml) did not directly affect the levels of ROS and MPO activity. However, under conditions that did not affect the viability of PMN, the ability of CB/fMLP to trigger production of intracellular ROS and release of MPO in human PMN was significantly suppressed by areca nut extract and arecoline.

CONCLUSION

Areca nut impaired the activation of PMN by CB/fMLP that might decrease the effectiveness of PMN in the host defense. Alternatively, exposure of PMN to areca nut extract could decrease the capacity of PMN to damage tissues.

A noninvasive oral rinse assay to monitor engraftment, neutrophil tissue delivery and susceptibility to infection following HSCT in pediatric patients

The time interval between neutrophil tissue delivery and blood confirmed engraftment following hematopoietic stem cell transplantation (HSCT) may serve as an indicator of patient susceptibility to infection. Using an oral rinse protocol, we studied neutrophil tissue delivery kinetics and its relationship to clinical parameters post-HSCT in 29 pediatric patients. Oral neutrophil counts were compared to circulating neutrophil levels, oral mucositis scores and infection-related febrile episodes after engraftment. Blood engraftment (BE) is currently defined by a blood neutrophil count of > or =0.5 x 10(9)/l. We defined oral engraftment (OE) as the day neutrophils returned in the mouth post-HSCT (> or =0.25 x 10(4)/ml oral neutrophils in the rinse sample). We found that neutrophils reappeared 6.3+/-3.9 s.d. days earlier in the mouth than in the circulation enabling us to identify successful engraftment almost 1 week sooner than using blood count values alone. Furthermore, the time-span between OE and BE was inversely related to the number of infection-related febrile episodes post-BE. We conclude that monitoring the timing of neutrophil tissue delivery through a rapid oral rinse may yield important insights into the biology of neutrophil recovery during and after engraftment and the factors associated with neutrophil tissue recruitment.

Caseinophosphopeptides and their cell modulating potential

In the context of the EU research project FAIR-CT 98-3077, studies were carried out to investigate caseinophosphopeptides (CPP) as potential ingredients for functional food and pharmaceutical applications. CPP preparations were produced by enrichment of CPP from hydrolytic casein digests. Enzyme preparations used for hydrolysis were PTN 3.0 S, Alcalase, Bioprotease P conc, Proteinase DS. Cytochemical studies were carried out to examine the cytotoxic potential or cell modulating activities of CPP using human cancer cell lines (HL-60, Caco-2) and non-malignant polymorphonuclear leukocytes (PML) from oral cavity. PML cells isolated by magnetic cell sorting using CD-15-antibody-labelled paramagnetic beads were used for the first time for testing food-derived peptides. Cell activity was measured by formazan dye formation. Effects on enterocytic differentiation properties of Caco-2 cells were examined by transepithelial membrane resistance of Caco-2 cell monolayers and brush border associated alkaline phosphatase activity. In conclusion, (1) no deleterious cytochemical consequences (apoptotic, antiproliferative or general cytotoxic effects) were observed on presenting a range of CPP preparations to various human cell systems, indicating that these compounds can be rated harmless at a cellular level, (2) stimulation of IgG-secretion into culture supernatant of PBL points to possible immunoenhancing properties of CPP preparations.

New revival of an old biomarker: characterisation of buccal cells and determination of genetic damage in the isolated fraction of viable leucocytes

Buccal cells serve as targets to assess oral exposures. We have refined isolation methods to characterise yield, viabilities, types of cells and baseline levels of genetic damage. Buccal cells were isolated from mouthwashes of 27 volunteers. They were characterised microscopically and different methods (using antibody-labelled magnetic beads, filtration and gradient centrifugation) were compared to separate epithelial cells from leucocytes. Viability of cells, DNA damage, and activity of glutathione S-transferase (GST) were measured with dye exclusion, microgelelectrophoresis, and biochemically. Mouthwashes contained approximately equal amounts of epithelial cells and leucocytes with detectable GST-activities. Repetitive determinations with mouthwashes from four individuals yielded per sample (3.5+/-1.4)x10(6) epithelial cells and (4.7+/-3.9)x10(6) leucocytes with viabilities of 8 and 94%, respectively. Epithelial cells could not be isolated using antibody-labelled beads, but cell separation with the leukocyte-specific antibody CD45 succeeded, yielding 37% leucocytes with a purity of 95% and viability of 65%. Filtering the mouthwash through a 10 microm filter yielded 57% leucocytes, with 86% purity and 94% viability. When using density gradient centrifugation as the separation method, the recovery of leucocytes was low (22%), but good results were scored for purity (95%) and cell viability (88%). This method was used to isolate leucocytes, which were then subjected to a micro-scale comet assay-modification. It was found that buccal leucocytes obtained from smokers had more DNA damage than cells from non-smokers. In conclusion, suspensions of buccal cells consist in approximately equal parts of epithelial cells and leucocytes. Only leucocytes are sufficiently viable for measuring parameters of cytotoxicity and genotoxicity or for studying modulation of gene expression. The cells are useful targets of non-invasive biomarkers, which could be incorporated as tools in many types of intervention studies.

Phagocytic functions of salivary neutrophils in oral mucous membrane diseases

BACKGROUND AND PURPOSE

Phagocytic functions of salivary polymorphonuclear neutrophils (sPMNs) have not been comprehensively studied in patients with oral mucous membrane diseases, although available data suggest the role of immunity in their pathogenesis.

SUBJECTS AND METHODS

Phagocytic functions of sPMN were determined in 15 patients with acute recurrent aphthous ulceration (RAU), 11 patients with oral lichen planus (OLP) and 20 healthy volunteers. In healthy subjects, the same parameters were also determined in peripheral blood polymorphonuclear neutrophils (bPMNs). Phagocytic activity (proportion of ingesting cells, PA), ingestion ability (number of ingested targets per 100 phagocytes, IA) and intracellular microbicidity (proportion of killed targets, IM) of PMNs separated from peripheral blood and the whole unstimulated saliva were determined by acridine orange method with living yeast cells as targets.

RESULTS

Salivary PMNs in healthy individuals showed significant reduction in PA (33% vs. 76%; P < 0.009) and IA (0.47% vs. 2.93%; P < 0.009) and significant increase in IM (12.0% vs. 5.5%; P = 0.011) in comparison with bPMNs. In RAU patients, reduced PA (27% vs. 37%; P = 0.035) and IA (0.25% vs. 0.47%; P = 0.05) were detected, while in OLP patients enhanced IM was detected (12% vs. 19%; P = 0.033) in comparison with healthy controls.

CONCLUSION

Salivary PMNs present functional features distinct from those in peripheral blood. Some phagocytic functions of sPMNs are reduced in RAU and enhanced in OLP, indicating their role in pathogenesis or reflecting clinical changes in these conditions.

Changes in the number of polymorphonuclear leukocytes and concentrations of IL-8 and granulocyte elastase in the vaginas of normal pregnant women

PROBLEM

It is unknown whether the number of vaginal polymorphonuclear leukocytes (vPMNs) of healthy pregnant women changes during pregnancy.

METHOD OF STUDY

We studied 23 women after 14.7 +/- 3.6 weeks, 37 women after 25.2 +/- 3.1 weeks, and 26 women after 32.9 +/- 2.0 weeks of gestation. Numbers of total vPMNs, viable vPMNs, dead vPMNs, percentage viability of vPMNs, and concentrations of IL-8 and elastase activity were determined in vaginal washings.

RESULTS

The vPMNs, including viable and dead vPMNs, significantly increased with advancing gestation from 9.9 +/- 8.6 x 10(5) to 13.1 +/- 13.4 x 10(5), and to 27.1 +/- 26.6 x 10(5) (r=0.315, P < 0.01). Vaginal IL-8 significantly increased with advancing gestation. However, increases in vaginal elastase activity did not occur.

CONCLUSIONS

These results suggested that an increase in vPMNs is an early event, and that the increase in vaginal elastase activity is a late event in relation to the ripening of the uterine cervix.

Regulation of Candida albicans growth and adhesion by saliva

To examine the local regulation of oral Candida albicans growth, we examined non-stimulated and stimulated salivary flow rates (SFRs) and the C. albicans growth and adhesion inhibitory activities of saliva in 60 patients with oral candidiasis (divided into two groups: 25 patients with oral candidiasis only (group OC) and 35 patients with oral candidiasis and systemic diseases (group CS)) and 30 healthy control subjects. Both non-stimulated and stimulated SFRs in patients, especially in group CS; were decreased in comparison with those in the healthy control subjects. The levels of secretory immunoglobulin A (sIgA) in group OC and group CS and the lactoferrin level in group CS were decreased as compared with those in control individuals, although there were no differences in transferrin and total secretory component (SC) levels between the three groups. The secretion amounts (microg/min) of these proteins were statistically significantly decreased in the patients, especially in group CS. Saliva from the patients showed a lesser inhibitory effect on C. albicans growth and adhesion to HeLa cells than did saliva from the control subjects. In addition, polymorphonuclear leukocytes (PMNs) in patients' saliva generated smaller amounts of superoxide than did those in control subjects' saliva, and phagocytic and C. albicans killing activities were suppressed in the patients. These results indicate that the decreases in SFR, secretion of antimicrobial proteins in saliva, and salivary PMN activity are risk factors for oral candidiasis associated with aging and systemic diseases.

Short exposure of polymorphonuclear leucocytes to sodium fluoride suppresses the response to fMLP

Fluoridated dental care products are used to prevent dental decay. Up to now, there are no data available on whether the fluoride (F-) component of these products affects the bactericidal activity of salivary polymorpho-nuclear leucocytes, which are involved in the protection of the oral mucosa against infection. Therefore, after determining the concentration/time profile of F- in mixed saliva of healthy subjects after topical application of 0.5 g of a 1.25% F- containing gel, unstimulated and fMLP-stimulated polymorphonuclear leucocytes (PMNs) were shortly exposed to these F- concentrations and the generation of superoxide and hypochloric acid were measured, as well as the liberation of lysomal enzymes, and correlated with the cellular Ca2+ and cAMP-levels. The results show that F-, at concentrations as retained in saliva, did not activate the oxidative burst in unstimulated PMNs. In fMLP-activated PMNs, F-suppressed the receptor-mediated increase in the oxidative burst and the liberation of fl-glucuronidase by reduction of the availability of extracellular Ca2+ and, thus, the influx of Ca2+ necessary to couple completely the fMLP signal to effector pathways. These F- concentrations neither altered the liberation of Ca2+ from internal stores nor induced a rise in cAMP. The possible clinical consequences of these results for xerostomic patients with respect to the generation of HOSCN/OSCN/SCN in saliva an important non-immune factor for oral health, are dicussed.

Separate oligosaccharide determinants mediate interactions of the low-molecular-weight salivary mucin with neutrophils and bacteria

The low-molecular-weight human salivary mucin (MG2) coats oral surfaces, where it is in a prime location for governing cell adhesion. Since oligosaccharides form many of the interactive facets on mucin molecules, we examined MG2 glycosylation as it relates to the molecule's adhesive functions. Our previous study of MG2 oligosaccharide structures showed that the termini predominantly carry T, sialyl-T, Lewisx (Lex), sialyl Lex (sLex), lactosamine, and sialyl lactosamine determinants [Prakobphol, A., et al. (1998) Biochemistry 37, 4916-4927]. In addition, we showed that sLex determinants confer L-selectin ligand activity to this molecule. Here we studied adhesive interactions between MG2 and cells that traffic in the oral cavity: neutrophils and bacteria. Under flow conditions, neutrophils tethered to MG2-coated surfaces at forces between 1.25 and 2 dyn/cm2, i.e., comparable to the shear stress generated at the tooth surface by salivary flow ( approximately 0.8 dyn/cm2). MG2 was also found in association with neutrophils isolated from the oral cavity, evidence that the cells interact with this mucin in vivo. Since MG2 serves as an adhesion receptor for bacteria, the MG2 saccharides that serve this function were also identified. Seven of 18 oral bacteria strains that were tested adhered to MG2. Importantly, six of these seven strains adhered via T antigen, sialyl-T antigen, and/or lactosamine sequences. No adherence to Lex and sLex epitopes was detected in all the strains that were tested. Together, these results suggest that distinct subsets of MG2 saccharides function as ligands for neutrophil L-selectin and receptors for bacterial adhesion, a finding with interesting implications for both oral health and mucin function.

Levels of human defensin-1, an antimicrobial peptide, in saliva of patients with oral inflammation

OBJECTIVE

The purpose of this study was to investigate the presence of an antimicrobial peptide, human defensin-1, in the saliva of patients with oral inflammation.

STUDY DESIGN

Whole saliva samples were collected from patients with oral inflammation and from healthy volunteers. Human defensin-1 in saliva was isolated and purified by reversed-phase high-performance liquid chromatography. The amino acid sequence and molecular weight of defensin-1 were determined. The concentration of defensin-1 in saliva was quantified by high-performance liquid chromatography. Serum C-reactive protein concentration was measured by particle-enhanced turbidimetric immunoassay.

RESULTS

The salivary defensin-1 concentration was significantly higher in patients with oral inflammation than in healthy volunteers; furthermore, in patients with oral inflammation, the concentration was significantly higher before treatment than after treatment. In the patients with oral inflammation, there was a strong positive correlation between salivary defensin-1 concentration and serum C-reactive protein concentration.

CONCLUSIONS

The findings suggest that defensin-1 in saliva may be a convenient marker of inflammation associated with oral disease.

Defensin-1, an antimicrobial peptide present in the saliva of patients with oral diseases

OBJECTIVES AND DESIGN

A preceding paper has noted a detection of defensin-1 (HNP-1), a peptide with antimicrobial and cytotoxic properties, in the saliva of patients with oral squamous cell carcinoma. The present study deals with the presence of HNP-1 in the saliva of patients with various oral diseases.

METHODS

Whole saliva samples were obtained from the patients. HNP-1 in the saliva was isolated and purified by HPLC and the amino acid sequence of the peptide was determined. The molecular weight of HNP-1 was measured by mass spectrometry. The concentration of HNP-1 in saliva was determined by comparing the height of eluted HNP-1 with that of a synthetic HNP-1 standard.

RESULTS

The concentrations of HNP-1 in the saliva of patients with oral lichen planus (n = 5), leukoplakia (n = 4), and glossitis associated with iron deficiency (n = 4) were 8.3 +/- 4.3 micrograms ml-1, 13.2 +/- 7.9 micrograms ml-1, and 11.4 +/- 4.9 micrograms ml-1, (mean +/- s.d.), respectively. These concentrations were significantly higher than those in healthy subjects (0.8 microgram ml-1) (P < 0.01). In contrast, salivary HNP-1 concentrations in patients with glossodynia (n = 4) and oral discomfort (n = 4) were similar to those in healthy subjects.

CONCLUSIONS

Since HNP-1 is a non-specific defensive peptide present in neutrophils, it may play an important role in the protection against diseases such as oral lichen planus, leukoplakia, and glossitis associated with iron deficiency.

Phagocytic function of salivary PMN after smoking or secondary smoking

Alterations in polymorphonuclear leukocyte (PMN) functions, such as phagocytosis, chemotaxis, and oxidative burst, play a pivotal role in periodontal pathogenesis. In addition, previous studies have demonstrated a strong relationship between smoking and periodontal disease. In the present study, the effect of cigarette smoking or passive smoking (secondary smoking) on the phagocytic function of salivary PMN (SPMN) was investigated. Twenty volunteers with clinically healthy gingiva (10 smokers, 10 non-smokers) participated in this study. In a small room, the smokers and passive smokers (non-smokers) were instructed to smoke and breathe, respectively, in an identical, specific way for about 4 minutes. SPMN was isolated immediately before and after smoking or passive smoking. PMN was then incubated with fluoresbrite beads for 45 minutes at 37 degrees C and the phagocytic status estimated by using a flow cytometer. Cell viability was determined by trypan blue exclusion (smokers before smoking: 88.3%: smokers after smoking: 89.6%: non-smokers before passive smoking: 89.0%; non-smokers after passive smoking: 89.4%). In both smokers and passive smokers, the proportion of phagocytic cells increased between before and after smoking (smokers before: 33.2%; after: 42.1%: passive smokers before: 36.2%: after: 44.1%). Both increases were statistically significant (P < 0.01). These results demonstrate that the phagocytic activity of SPMN intensifies after smoking and passive smoking. They also suggest that certain substances in cigarette smoke, perhaps nicotine, overstimulate the host response in the oral cavity.

Comparison of susceptibility to apoptosis induced by rhTNF-alpha and cycloheximide between human circulating and exudated neutrophils

To determine whether exudated neutrophils differ from circulating ones in their apoptosis, rhTNF-alpha plus cycloheximide-induced apoptosis in human salivary neutrophils was compared to that in human neutrophils in peripheral blood. Concomitant treatment of peripheral blood neutrophils with rhTNF-alpha and cycloheximide-induced apoptosis in blood neutrophils within 3 hr, as evaluated both by light microscopic changes characteristic to apoptosis and by DNA fragmentation, whereas the same treatment failed to induce any apoptosis in salivary neutrophils. These results indicate that the exudation of neutrophils from blood into tissue is associated with marked changes in their functions such as alteration in their sensitivity to apoptosis-inducing stimuli.

Interleukin-1 beta gene expression in human oral polymorphonuclear leukocytes

Oral polymorphonuclear leukocytes (PMN) were obtained from 10 adult donors in good oral health using a method employing repeated mouth rinse collection. Interleukin-1 beta (IL-1 beta) mRNA was detected in freshly obtained cells by blot hybridization of total cellular RNA with a biotin labeled cDNA probe. Supernates from oral PMN placed in culture for 3 hours contained substantial amounts of IL-1 beta measured by ELISA. Significantly greater numbers of PMN and amounts of PMN-derived IL-1 beta were obtained from the same donors 2 hours subsequent to an oral sucrose challenge (3.23 x 10(6) vs. 1.57 x 10(6) mean PMN number, P = 0.004; 59.80 vs. 20.05 mean pg/ml IL-1 beta, P = 0.036, respectively). However, the elevated levels of IL-1 beta were due to the higher cell number rather than to increased production by individual cells. Stimulation of oral PMN with recombinant granulocyte-macrophage colony stimulating factor did not enhance their cytokine production. In most instances. IL-1 beta production by oral PMN was dramatically greater than that of their blood counterparts. These findings suggest that oral PMN are an important source of IL-1 beta, which plays a central role in oral immunity and inflammatory disease states.

Salivary up-regulation of human polymorphonuclear leucocyte chemotaxis and adhesion-molecule expression

Chemotaxis and adhesion molecules were investigated in peripheral blood neutrophils incubated with saliva collected from healthy donors. A salivary concentration of 20% increased chemotactic responses and CD11a/CD18 and CD11b/CD18 expression, but had no effect on formyl-methionyl-leucyl-phenylalanine receptors.

Influence of inductive chemoradiotherapy on salivary polymorphonuclear leukocyte (SPMN) functions in oral cancer

Salivary polymorphonuclear leukocyte (SPMN) functions were examined in 18 patients with oral squamous cell carcinoma and in 20 healthy individuals. SPMN obtained from patients before therapy exhibited significantly less FMLP-stimulated chemotactic activity (132.4 +/- 17.5 cells/0.26 mm2) than that in SPMN from controls (177.1 +/- 11.6 cells/0.26 mm2), although no difference in phagocytosis was observed. When stimulated with PMA or FMLP, control SPMN generated superoxide (O2-) at levels of 50.3 +/- 10.5 pmol/min/10(4) cells and 88.4 +/- 15.4 pmol, respectively, while SPMN from untreated patients generated significantly reduced O2- in the presence of PMA or FMLP (24.3 +/- 3.5 pmol and 59.5 +/- 9.8 pmol, respectively). Only slightly lower chemiluminescence was observed in SPMN from untreated patients however, compared to controls, values being 68.0 +/- 18.9 vs 81.3 +/- 14.9 peak mV by PMA and 62.4 +/- 13.7 vs 64.4 +/- 12.9 peak mV by FMLP. Compared to Candida killing in control subjects (24.9 +/- 3.1%). SPMN from patients before treatment exhibited significantly reduced activity (18.7 +/- 4.9%). Further suppression of the SPMN functions examined was observed after chemoradio-therapy. Suppressed SPMN function in cancer patients, especially that associated with chemoradiotherapy, may therefore play a part in oral candidiasis.

Elastase release from gingival crevicular and peripheral neutrophils in periodontitis and health

The activity of elastase increases significantly in the gingival sulcus during inflammation. The release of this enzyme from crevicular and peripheral polymorphonuclear leucocytes (PMNs) was studied in seven patients with gingivitis, six with adult periodontitis, seven with rapidly progressive periodontitis and in nine healthy subjects. Peripheral PMNs were isolated from blood and crevicular PMNs from gingival washings. After preincubation with cytochalasin B, the same numbers of crevicular and peripheral cells were incubated either in phosphate-buffered saline (spontaneous release) or in the same buffer containing formyl methionyl-leucyl-phenyl-alanine (stimulated release). Elastase activity was measured in the supernatant by a fluorimetric technique. The results confirm that compared to peripheral PMNs, crevicular cells show a higher spontaneous release of elastase and a lower stimulated release. The activity of elastase released either spontaneously or after stimulation of crevicular cells was significantly lower in the controls as compared with cells obtained from patients with gingivitis or periodontitis. Crevicular PMNs collected from patients with deeper pockets appear to release larger amounts of elastase than those from controls.

Antimicrobial factors, sialic acid, and protein concentration in whole saliva of the elderly

Concentrations of salivary antimicrobial factors are well documented in children and young adults, but little information is available on such defense factors in healthy elderly persons. We determined the levels of total IgA, total IgG, lysozyme, lactoferrin, myeloperoxidase, salivary peroxidase, amylase, sialic acid, and total protein in a group of 71 subjects aged 76, 81, and 86 yr, as well as their correlations to paraffin-wax-stimulated salivary flow rate. Participants were either unmedicated (n = 67) or using medicines with no oral significance (n = 4). Statistically significant negative correlations existed between flow rate and total IgA, lysozyme, lactoferrin, sialic acid, and total protein. Concentrations of sialic acid and salivary peroxidase were highest in the oldest age group. Total IgA concentration was higher in women than in men, although men showed higher concentrations of sialic acid and higher sialic acid/total protein ratios. Subjects with poor gingival health had higher concentrations of total protein than did those with no need for periodontal treatment. Edentulous subjects with complete dentures showed significantly lower concentrations of IgG, lactoferrin, and myeloperoxidase than did dentate subjects. Our results suggest that, when compared with data from previous studies, concentrations of salivary antimicrobial agents do not decline with age in unmedicated elderly people. However, defense factors which are derived also from gingival crevicular fluid are decreased in the absence of teeth.

A proposal for purification of salivary polymorphonuclear leukocytes by combination of nylon mesh filtration and density-gradient method: a validation by superoxide- and cyclic AMP-generating responses

Isolation and purification of salivary polymorphonuclear leukocytes (SPMNs) from accompanying epithelial cells was presented by using a density-gradient method with Ficoll. SPMNs samples prepared by already established methods (nylon mesh filtration) was compared with SPMNs samples after further purification by Ficoll (d = 1.083). Microscopically, SPMNs samples after nylon mesh filtration contain higher percentage of epithelial cells than SPMNs samples after Ficoll centrifugation. In response to stimulation of superoxide generation, both samples showed the same pattern of response. However, in response to forskolin and prostaglandin E1, cyclic AMP levels in samples after nylon mesh purification were significantly higher than in samples after Ficoll purification because of the presence of contaminating epithelial cells. We can conclude that, although nylon mesh filtration is satisfactory when we need to examine superoxide generation but further purification is necessary when we want to measure factors like intracellular cyclic AMP formation.

Killing of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus by human polymorphonuclear leukocytes in serum and saliva

The ability of polymorphonuclear leukocytes from human peripheral blood to kill Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus was examined with fresh isolates and laboratory strains from each species (5 strains within each group) under different conditions. Bacterial cells were mixed with a polymorphonuclear leukocyte suspension in the presence of either active serum or heat-inactivated serum or active serum together with sterile-filtered saliva. Surviving bacteria were determined by counting the number of bacterial colony-forming units in the mixtures after a 60-min incubation at 37 degrees C. Mixtures without polymorphonuclear leukocytes served as controls for the evaluation of the degree of killing of the bacteria. In general, A. actinomycetemcomitans resisted phagocytic killing to a greater extent than H. aphrophilus, and the killing of the former species mainly depended on the presence of heat-labile serum components, probably complement factors. Laboratory strains of A. actinomycetemcomitans were more easily killed than fresh isolates. The presence of saliva in the reaction mixtures decreased the degree of killing. However, strain-dependent variations in the killing were found under either condition. The leukotoxic activity of A. actinomycetemcomitans strains, determined by a [51Cr]-release assay, was not correlated with the resistance of these strains to the phagocytic killing. The results point out a strain-dependent difference in the ability of A. actinomycetemcomitans to evade the inflammatory response associated with polymorphonuclear leukocytes. This difference may constitute a potential virulence factor for this periodontopathogen. Furthermore, the leukotoxicity of the strains is not the main determinant that modifies the interaction of A. actinomycetemcomitans with human neutrophils.

Preserving avulsed teeth for replantation

We performed a retrospective study of 34 replanted avulsed teeth placed in an EPTS before replantation. Even when extraoral time was 120 minutes or more, 91 percent of the teeth showed excellent or moderate success for follow-up periods ranging from three to 30 months. We think that the success of a replanted avulsed tooth is increased by use of a prefabricated tooth preserving and protecting system as described.

Neutrophil modulation by Actinobacillus actinomycetemcomitans. II. Phagocytosis and development of respiratory burst

Compromised neutrophil function has been found in a number of patients with localized juvenile periodontitis (LJP), although the pathogenic mechanism is unknown. Since infection with Actinobacillus actinomycetemcomitans is frequently found in patients with LJP, we have evaluated in vitro the effect of a bacterial extract of A. actinomycetemcomitans on the development of the respiratory burst by neutrophils. Pre-incubation of neutrophils with bacterial extract increased H2O2 induced by FMLP and zymosan in a dose-dependent fashion. Substitution of FMLP for bacterial extract produced similar results. Moreover, FMLP and bacterial extract had an additive effect on superoxide production following phagocytosis of zymosan. In contrast, bacterial extract significantly decreased PMA-stimulated H2O2, but pre-incubation with FMLP instead of bacterial extract failed to decrease PMA-stimulated H2O2. Bacterial extract did not change the percentage of cells activated by FMLP, opsonized zymosan, or PMA. Heat-treated bacterial extract induced effects similar to non-treated extract. Bacterial extract treated with proteinase K or phenol extraction increased FMLP or zymosan stimulated H2O2 equivalent to non-treated bacterial extract. In contrast, proteinase K or phenol extraction abolished the inhibitory effect of bacterial extract on PMA-stimulated H2O2 production. The bacterial extract component(s) that inhibits PMA-stimulated H2O2 is therefore a protein(s), resistant to 56 degrees C, and is not endotoxin. The partially activated state of PMNs exposed to A. actinomycetemcomitans extract, combined with their reduced ability to respond to a protein kinase C-dependent stimulus, may partially explain the abnormalities noted in LJP patients.

Neutrophil modulation by Actinobacillus actinomycetemcomitans I. Chemotaxis, surface receptor expression and F-actin polymerization

Localized juvenile periodontitis is an early onset periodontitis, usually localized to molars and incisors. Patients usually present with decreased chemotaxis of systemic neutrophils (PMNs) and infection with Actinobacillus actinomycetemcomitans. The pathogenic mechanisms involved have not been clarified. The purpose of this study was to determine if an extract of A. actinomycetemcomitans could induce changes in PMN chemotaxis similar to those reported in LJP patients. It was demonstrated that the bacterial extract was chemotactic for neutrophils. When neutrophils were pre-incubated with the bacterial extract, chemotaxis toward zymosan-activated serum, FMLP and the bacterial extract was inhibited in two different chemotaxis assays (Boyden chamber and under-agarose). Bacterial extract had no effect on random migration in either assay. Pre-incubation with the extract induced increased expression of CD11b/CD18 (Mac-1), Gp110, and FMLP receptors and increased F-actin polymerization following FMLP or PMA stimulation compared to cells not treated with the extract. Treatment of the bacterial extract with proteinase K or phenol extraction reversed the PMN chemotaxis inhibition activity, but increased significantly the random migration of PMNs. Heating the bacterial extract to 56 degrees C had no effect on its activity. The component(s) in the bacterial extract that inhibits chemotaxis is therefore a protein(s), not sensitive to 56 degrees C, and is not endotoxin. This study suggests that A. actinomycetemcomitans may contribute to the pathogenesis of localized juvenile periodontitis by inhibiting chemotaxis. Interference with chemotaxis by A. actinomycetemcomitans, however, occurs through a mechanism other than inhibition of actin assembly, reduction of CD11b/CD18 or Gp110 expression, or blockage/downregulation of FMLP receptors.