Neutrophil chemotactic behaviour in patients with early-onset forms of periodontitis (II). Assessment using the under agarose technique

Neutrophils and neutrophil extracellular traps in oral health and disease

Neutrophils perform essential functions in antimicrobial defense and tissue maintenance at mucosal barriers. However, a dysregulated neutrophil response and, in particular, the excessive release of neutrophil extracellular traps (NETs) are implicated in the pathology of various diseases. In this review, we provide an overview of the basic concepts related to neutrophil functions, including NET formation, and discuss the mechanisms associated with NET activation and function in the context of the prevalent oral disease periodontitis.

How has neutrophil research improved our understanding of periodontal pathogenesis?

BACKGROUND

Neutrophils are the predominant cells responsible for host defence against bacterial infection. Loss of neutrophil defence, due either to deficient number or function, strongly predisposes to bacterial infections such as periodontitis. Yet, the neutrophil oxidative and proteolytic arsenal has also been implicated in perpetrating periodontal tissue damage in periodontitis.

AIM

In this review, we focus on recent developments that shed light on these two aspects of neutrophil function in periodontitis.

METHODS

Primary search: using PubMed search for "neutophil", "periodontal", and "periodontitis". Secondary search: using references from the articles found in the first stage.

RESULTS

Early histological studies showed that infiltrating neutrophils form a wall of cells abutting the junctional epithelium in periodontal inflammatory lesions. The chronic standoff between these neutrophils and the bacterial community suggests that bacterial evasion of neutrophil clearance is a major characteristic of periodontitis. Indeed, not all functional neutrophil deficiencies increase the risk of periodontitis, an observation that points the way towards identification of particular anti-bacterial pathways essential for protection against periodontal pathogens. The net result in the majority of periodontitis patients who exhibit normal neutrophil number and function, is that neutrophils accumulate in the periodontal tissue where they are available to participate in tissue destruction. Diminished neutrophil clearance further contributes to the persistence of activated neutrophils in the periodontal tissue.

CONCLUSIONS

Data on the role of neutrophils in the pathogenesis of periodontitis are mixed. Neutrophils are a critical arm of the defence against periodontitis, but bacterial evasion of the neutrophil microbicidal machinery coupled with delayed neutrophil apoptosis may transform the neutrophil from defender to perpetrator. At this stage of knowledge, attempts to induce host modulation through neutrophil suppression or activation are premature.

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.

Polymorphonuclear neutrophils and their mediators in gingival tissues from generalized aggressive periodontitis

BACKGROUND

Impaired polymorphonuclear neutrophil (PMN) functions were generally considered to be related to the onset of generalized aggressive periodontitis (GAgP). However, some research has indicated that the hyperreactivity of PMN seems to be involved in the inflammatory response of GAgP. The present study's main purpose was to provide more evidence about the role of PMN in the pathogenesis of GAgP by surveying PMN infiltration in gingiva and its relationship with the expression of their mediators including intercellular adhesion molecule-1 (ICAM-1), interleukin-8 (IL-8), interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha). The inflammatory response in GAgP was also compared with that in adult periodontitis (AP) and periodontally healthy subjects. Since these PMN mediators were reported to be produced mainly by macrophages, the association between the expression of these PMN mediators and the distribution of macrophages was also investigated.

METHODS

A total of 25 gingival specimens were obtained from 10 GAgP patients, 10 AP patients, and 5 periodontally healthy subjects. Serial sections were obtained from each specimen, and the following techniques were adopted to investigate the distribution and interrelation of different cells and cytokines. Infiltration of PMN was observed by using hematoxylin and eosin staining. Distribution of the macrophages, identified as CD68+, was shown by using immunohistochemistry. Immunohistochemistry and in situ hybridization were used to detect the expression of ICAM-1, IL-8, IL-1beta, and TNF-alpha in gingival tissues. These techniques were performed in serial sections from each individual specimen.

RESULTS

Large numbers of infiltrating PMNs were observed in gingiva from GAgP. In gingiva from both GAgP and AP, the strongest protein and mRNA expression of IL-8, ICAM-1, IL-1beta, and TNF-alpha were located in pocket epithelium and adjacent connective tissue with large numbers of infiltrating PMNs. In tissues without abundant PMN infiltration, the appearance of positive cells expressing IL-8, ICAM-1, IL-1beta, and TNF-alpha was scattered. CD68+ was distributed sparsely in connective tissue and was hardly seen in pocket epithelium with large numbers of PMN infiltration. The degree of leukocyte infiltration and connective tissue destruction in gingiva from GAgP patients was not distinctly different from that in gingiva from AP. The gingival specimens with heavy PMN infiltration from both GAgP and AP patients presented strong expressions of IL-1beta and TNF-alpha; showed more extensive inflammatory cell infiltration; had severe connective tissue destruction; and presented severe elongation and ulceration of pocket epithelium. In gingiva from healthy subjects, inflammation was minor with visually no PMN, CD68+, or the positive cells of IL-8, ICAM-1, IL-1beta and TNF-alpha expression.

CONCLUSIONS

Enhanced accumulation of PMN, which is associated with the upregulation of IL-8, ICAM-1, IL-1beta, and TNF-alpha expression, relates to the severity and activity of GAgP. In addition to macrophages, PMN and/or epithelial cells might also be important sources of IL-8, IL-1beta, and TNF-alpha production in gingiva.

Early-onset periodontitis

In 1993, the 1st European Workshop on Periodontology explicitly recognized that there was insufficient knowledge to differentiate truly different forms of periodontal disease from differences in the presentation/severity of the same disease. In spite of recent progress in our understanding of periodontal diseases, the issue is far from having been resolved. Classification of periodontal diseases, therefore, remains based upon the definition of specific clinical syndromes. Early-onset periodontitis (EOP) is one such syndrome and comprises a group of pathological conditions leading to loss of periodontal tissues early in life. The notion that classifies periodontitis syndromes as "early-onset" or "adult" is primarily epidemiological in nature and is based on the observation that periodontitis is rather infrequent in children and young adults. Nevertheless, considerable epidemiological evidence indicates that periodontitis does affect children and young adults to a level of severity that may lead to premature exfoliation of primary and/or permanent teeth. Clinical presentation of periodontitis early in the life of an individual is thought to indicate that the etiologic agents have been able to cause considerable tissue damage over a relatively short period of time. It also implies either infection with highly virulent bacteria and/or a highly susceptible subject. The purpose of this review is to discuss the criteria generally utilized to classify EOP, provide the rationale to designate EOP as a distinct disease entity, and to review the evidence justifying a subclassification into particular subgroups of EOP.

Smoking and patterns of bone loss in early-onset periodontitis

BACKGROUND

The aims of this study were to investigate the extent and distribution of bone loss in subjects with early-onset periodontitis (EOP) referred for periodontal care and to study the relationship between smoking and EOP.

METHODS

A total of 71 consecutive referrals (21 male, 50 female) under 35 years old, who were otherwise healthy, with a clinical diagnosis of severe periodontitis were recruited for the study. Bone loss was measured from available radiographs using a Schei ruler to identify 2 patterns of destruction: localized (LEOP) in 41 (58%) and generalized early-onset periodontitis (GEOP) in 30 (42%) subjects.

RESULTS

The study population had a mean of 25.0 (SD 2.4) teeth, excluding third molars, and mean bone loss of 28.7% (SD 13.0). Bone loss was more severe in the maxilla, 30.9% (SD 13.8) compared with 26.6% (SD 14.0) in the lower arch. More than one-third (36%) of the teeth examined had at least 30% bone loss. Mean smoking experience was 9.2 pack years (SD 5.6), and 39 (55%) of the EOP subjects smoked. Smokers had significantly more maxillary bone loss than non-smokers. A much higher proportion of GEOP (70%) currently smoked compared with 44% of LEOP, P = 0.029.

CONCLUSIONS

It is concluded that young adults with early-onset forms of periodontitis often have advanced periodontal destruction before they are referred for specialist care. In addition, there was a relationship between smoking and severe bone destruction in subjects with EOP, particularly those with generalized disease.

Regression coefficient analysis of neutrophil chemotaxis in periodontitis

Micropore-filter techniques have been widely used to assess motility and chemotaxis of neutrophils. In some cases the results were impaired by inadequate methods of evaluation and failures of the test system. For clinical purposes the mode of test evaluation should be able to differentiate between failures of the test system (false-negative) and real functional defects (true-negative). A new method has been developed to check parallel assays for homogeneity. Based on earlier procedures this type of evaluation uses the comparison of regression coefficients to identify false-negative test results within the cell population of an individual. The newly developed method was used to study the chemotactic response in a group of 49 patients and 22 healthy volunteers. Intraclass correlation coefficients of the regression coefficient analysis and the leukotactic index were calculated and compared. It could be demonstrated that the regression coefficient analysis had the same sensitivity as the leukotactic index. Slight variations in the cell counts at a single plane of the chemotactic filter affecting the leukotactic index by 18% had no measurable influence on the calculated regression coefficient.

Cytoskeletal actin reorganization in neutrophils from patients with localized juvenile periodontitis

Localized juvenile periodontitis (LJP) is an early-onset periodontal disease associated with a polymorphonuclear neutrophil (PMN) defective migratory response. Kinetics of actin polymerization-depolymerization determine the shape changes occurring in the plasma membrane-associated cytoskeleton and provide the driving force for directed cell migration (chemotaxis). Therefore, we investigated the relation between an abnormality in LJP PMN chemotaxis and an altered reorganization of the actin filament network. PMNs isolated from peripheral blood of LJP patients (n=14) and matching control subjects (n=12) were evaluated for random and directed migration in a Boyden chamber assay, and the kinetics of actin polymerization were studied by flow cytometry. Three groups of LJP patients could be distinguished on the basis of their PMN-chemotactic response compared to their matched control: depressed (n=6), normal (n=4), and elevated (n=4). The abnormal (depressed or elevated) chemotaxis was generally not related to abnormal random migratory response, except for two patients. Since the kinetics of formyl-methionyl-leucyl-phenylalanine-induced F-actin response were highly variable from one subject to another, means were calculated at each timepoint with the values obtained from each group of subjects and compared by a general factorial design analysis. No statistically significant differences were detected between the control group and the LJP patient group. Furthermore, the data did not show a correlation between the kinetics of actin polymerization-depolymerization and the abnormal chemotactic response observed in LJP PMNs. Hence, the chemotaxis defect in LJP PMN appears to be mediated by signaling events that carry their effect independently of an intact cytoskeleton.

Peroxidases, lactoferrin and lysozyme in peripheral blood neutrophils, gingival crevicular fluid and whole saliva of patients with localized juvenile periodontitis

OBJECTIVE

The aim of this study was to examine the longitudinal association of selected non-immune anti-microbial host factors (peroxidases, lysozyme and lactoferrin) to the localized juvenile periodontitis (LJP) disease status.

MATERIALS AND METHODS

Peroxidases, lysozyme and lactoferrin were quantitated from seven patients with LJP before and after periodontal therapy. Analyses were performed from simultaneously collected samples of peripheral blood polymorphonuclear leukocytes (PMNs), gingival crevicular fluid (GCF from diseased sites) and paraffin-stimulated whole saliva. Similar assays were done also from seven periodontally healthy controls.

RESULTS

During untreated phase of LJP myeloperoxidase, lysozyme and lactoferrin concentrations were remarkably elevated in peripheral blood PMNs, also reflected in their high concentrations in GCF. All these values normalised with respect to healthy controls during the periodontal therapy. No similar longitudinal changes were seen in whole saliva but during therapy salivary peroxidase concentrations declined below the control values, in accordance with our previous observations in parotid saliva samples of LJP patients.

CONCLUSIONS

In LJP the concentrations of lysozyme, lactoferrin and myeloperoxidase are significantly elevated in peripheral blood PMNs, also reflected in GCF. During periodontal therapy these values decline and approach those observed in healthy controls. No similar changes are seen in stimulated whole saliva.

Periodontal inflammation and attachment loss: a critical problem for biological studies

BACKGROUND

In biological studies of periodontitis, there has been long-standing confusion between the ubiquitous phenomena of inflammation and the essential criterion of attachment loss. This is partly attributable to inadequate methods of clinical measurement, but seems also to be a consequence of an unproven and usually unstated assumption that the same biological processes underlie both inflammation and attachment loss. Developments in unidimensional clinical probing methods have helped in studies of periodontal treatment. However, such methods are intrinsically unsuitable in studies of periodontal diseases, and may have given them a false sense of security. the confusion has been compounded by inappropriate use of statistical techniques in an attempt to solve problems which do not arise from mathematical models but are intrinsic to measurement methods.

OBJECTIVE

This paper is a clinician's attempt to state the current difficulties and suggest some ways forward, including the development of three-dimensional measurement, non-invasive probing, and several objectives for biochemical, microbiological and immunological research.

Ex vivo studies of polymorphonuclear neutrophils from patients with early-onset-periodontitis (II). Chemiluminescence response analysis

Previous studies have indicated that oxygen-free radicals may cause damage to the periodontal tissues. This study compared the luminol-dependent chemiluminescence response (after stimulation with either opsonized zymosan or phorbol myristate acetate (PMA) of peripheral blood polymorphonuclear leukocytes (PMN) isolated from human subjects with a healthy periodontium (n = 7), gingivitis (n = 8), adult periodontitis (n = 8), or early-onset periodontitis (n = 17). These results were also compared with those obtained in a larger reference group which consists of 50 subjects without infection or inflammation, selected on the basis of laboratory investigations. An enhanced response was defined as being 2 standard deviations above the reference group mean; a reduced response was defined as being 2 standard deviations below this mean. Although PMN from patients with either gingivitis or periodontitis were often functionally activated (when compared to the PMN from the reference group), no significant differences could be found between the 4 groups, with regard to the chemiluminescence response means obtained in a basal state or after stimulation.

Preventive therapy for periodontal diseases

Rational approaches to the prevention of destructive periodontitis should be based on a clear understanding of etiology and pathogenesis. However, we are dealing with a heterogeneous family of diseases in which different factors operate. It is an oversimplification to regard poor oral hygiene, and hence an accumulation of non-specific dental bacterial plaque, as the major risk factor. Epidemiological evidence indicates that host factors are likely to be of overriding importance for the most severe forms. The limitations of nonspecific plaque control are therefore discussed. Specific inhibitors of virulence factors provide a logical approach, but their clinical application awaits improved knowledge. Improvement of general health and resistance to disease by proper nutrition, the avoidance of intercurrent disease, and elimination of smoking and stress-induced risk are encouraged. The genetic basis of susceptibility to periodontitis is increasingly understood, and, while gene therapy is not likely to be a practicable approach to prevention, genetic markers of risk are emerging.

Role of cytokines in the modulation of neutrophil chemotaxis in localized juvenile periodontitis

Decreased neutrophil chemotaxis has been implicated in the pathophysiology of the disease, localized juvenile periodontitis (LJP). The biological basis for the altered neutrophil function in LJP has been suggested to be an intrinsic cellular defect, involving a decrease in the number of N-formyl-methionyl-leucyl-phenylalanine (FMLP) receptors on the cell surface. We have investigated the relative contribution of serum-borne factors in the modulation of neutrophil functions in LJP, in a large population of LJP patients and healthy control subjects (HS). Treatment of HS-neutrophils with LJP-sera, resulted in a decreased neutrophil chemotactic response, and down regulation of FMLP receptors on the cell surface. Pretreatment of LJP-sera with anti-TNF and anti-IL-1 antibodies effectively, although incompletely, neutralized the ability of LJP-sera to modulate chemotaxis and FMLP receptor levels in HS-neutrophils. The changes induced by LJP sera were specific and sustained and could not be reversed by placing LJP-serum treated neutrophils in HS-serum. Sera obtained from HS and patients with adult periodontitis (AP), both of which exhibit normal chemotaxis, and patients with clinically diagnosed LJP with normal neutrophil chemotaxis (LJP-nctx) did not modulate HS neutrophil chemotaxis or FMLP receptors. Furthermore, recombinant human TNF-alpha, rhIL-1 alpha and rhIL-1 beta, at very low concentrations (15 pg/ml to 150 pg/ml), modulated the chemotactic response as well as FMLP receptor numbers on HS-neutrophils, in a manner similar to those observed in LJP. The present findings demonstrate that the biologic basis for the altered neutrophil function may not be an intrinsic cellular defect in neutrophils, but at least in part due to quantitatively small but biologically significant elevations in the levels of TNF-alpha and IL-1 in the serum.

Ex vivo studies of polymorphonuclear neutrophils from patients with early-onset forms of periodontitis. (I). Chemotactic assessment using the under agarose method

The polymorphonuclear neutrophil (PMN) appears to be an important cell in the protection of the host from pathogenic periodontal microorganisms and, despite some reports to the contrary, it is generally assumed that early-onset forms of periodontal disease (including both juvenile and rapidly progressing periodontitis) are associated with a defect in PMN chemotactic behaviour. The purpose of the present study was to examine the peripheral PMN chemotactic behaviour, using the under agarose method, in 4 groups, namely healthy periodontium group (n = 7), gingivitis group (n = 8), early-onset periodontitis group (n = 17) and adult periodontitis group (n = 8). PMN from early-onset periodontitis patients showed normal random and chemotactic locomotory behaviour when compared with those of PMN from subjects of the other groups. No statistically significant difference could be found among the 4 studied groups, with regard to spontaneous and oriented migration.

A skin window study of neutrophil migration in subjects with localized juvenile periodontitis

This study investigated the effect of a chemoattractant, N-formyl-methionyl-leucyl-phenylalanine (FMLP), upon skin window migration of neutrophils into filters in 5 patients with a history of localized juvenile periodontitis (LJP) and 8 controls. On 2 occasions, each subject had 2 superficial skin abrasions made on the inner aspect of the forearm. Initial periodontal treatment was carried out on the disease group between the visits. On one skin window filters were placed that were soaked in physiological saline, and on the other filters soaked with FMLP. Leading fronts and cell densities were measured in each filter. At visit 1, LJP subjects had significantly lower leading fronts and cell densities. At visit 2, the differences were insignificant. The leading fronts for the LJP group were significantly improved on the second visit. No difference was observed between saline and FMLP. The findings of this study indicate that neutrophil migration is reduced in LJP patients where treatment is not involved, and that FMLP has no effect on neutrophil migration from the skin windows under the conditions of this study.

Differential diagnosis in clinical trials of therapy for periodontitis

For purposes of clinical trials of therapies for periodontitis, it is recommended that population samples be identified as adult periodontitis (systemically modified or not systemically modified), early onset periodontitis (localized or juvenile, generalized or rapidly progressive, or associated with systemic disease), or necrotizing ulcerative periodontitis, avoiding overlapping criteria. Population samples of adult or early onset periodontitis modified by or associated with systemic conditions should be used in clinical trials only when the intent is to study effect on the specifically modified condition. Objective identification of the modifying systemic condition should be required for all subjects in such trials. Population samples should be homogeneous for the diagnosis, whether systemically modified or not. Refractory periodontitis, prepubertal periodontitis, and periodontitis associated with systemic disease are not recommended as useful descriptors of population samples without discrete identification of underlying systemic abnormality for all included subjects. Definition of population sample by a bacteriological or a host response feature is not recommended unless the trial is specifically aimed at that feature and the sample is homogeneous for it. All trials of efficacy should include physical or radiographic measurement of attachment level or bone height as a critical outcome variable. Results from trial in one form of periodontitis should not be applied directly to other forms.

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.

Flow cytometric evaluation of phagocytosis by peripheral blood polymorphonuclear leucocytes in human periodontal diseases

The complement-dependent phagocytic functions of polymorphonuclear leucocytes (PMNL) in peripheral blood from 15 patients with localized juvenile periodontitis (LJP), 13 with generalized juvenile periodontitis (GJP) and 52 with adult periodontitis (AP), and from 30 normal subjects as controls were measured by flow cytometry. Heparinized blood was collected and incubated with fluorescent microspheres, and erythrocytes were removed. By means of single-cell analysis the percentage of phagocytosing cells (% phagocytosis) and the mean number of microspheres phagocytosed by one PMNL (degree of phagocytosis; d-phagocytosis) were measured. Some but not all patients with LJP (53%) and GJP (46%) showed consistently low % phagocytosis and d-phagocytosis. On the other hand, only 6% of AP patients and no healthy subjects showed a reduction of PMNL phagocytosis. Phagocytosis was unchanged after initial periodontal treatment in all subjects, suggesting the depression of PMNL phagocytosis may not be a transient phenomenon associated with periodontal status. Furthermore, PMNLs from the LJP patients that showed depressed phagocytic function exhibited depressed phagocytic responses with either autologous or normal plasma, while control PMNLs with either normal or the patients' plasma showed normal responses. These results suggested that the depressed phagocytic responses in LJP patients could be due to cell-associated defect(s) on the PMNL.

Clinical, laboratory, and immunological studies of a family with a high prevalence of generalized prepubertal and juvenile periodontitis

A study of a consanguineous family with a high prevalence of localized juvenile periodontitis (LJP) and generalized prepubertal periodontitis (GPP) was done over a 7-and-a-half year period. The parents had adult periodontitis, while 2 daughters, aged 13 and 15, had LJP. Furthermore, 2 other daughters, ages 14 and 10, and a son, aged 9, were affected by GPP. Two remaining siblings were not affected. Clinical and radiographic examinations on all family members were done, and chemotaxis for blood neutrophils was assessed. Laboratory tests, immunological examinations, and evaluation for neutrophil functions were done on the GPP patients. Microbiological cultures were performed on 2 of the GPP patients, as well as in the mother. The mother, the 2 LJP patients, and 1 of the unaffected siblings had depressed PMN chemotaxis. The other family members, including the 3 GPP patients, had normal PMN chemotaxis. GPP patients did not have any systemic disease, and evidence of major defects in the immunological functions was not detected. LJP patients were successfully treated with root planing, subgingival curettage, and tetracycline therapy. Intensive periodontal therapy, combined with systemic administration of antibiotics, was not effective in halting periodontal tissue destruction in the 3 GPP patients. Results indicate that the underlying cause of GPP is not always related to leukocyte dysfunction. Since Actinobacillus actinomycetemcomitans was the most frequent pathogen found in subgingival microflora of 2 of the GPP patients, it is assumed that it may play a key role in the etiology of GPP.

Immunologic mechanisms of pathogenesis in periodontal diseases: an assessment

Principal lines of evidence that immune reactions are central to the pathogenesis of periodontitis are reviewed. Necessary components of immunologic reactions are present in gingiva in the periodontal diseases. Differences between healthy and periodontitis patients with respect to some measures of immune function further indicate that immune reactions do occur in the gingiva during periodontitis. They are probably responsible for at least some of the destruction of connective tissue and bone that occurs. Classical antibody-mediated hypersensitivity reactions probably do not provide the reasons. Mechanisms are more likely to be found in the pro-inflammatory and tissue-degrading effects of cytokines released in host-protective, antigen-specific and polyclonal responses to oral bacterial constituents or products. Some evidence suggests that limitation of clinical destruction in localized early onset periodontitis (JP) may in part be a function of a protective antibody response which develops after an initial rapidly progressive infection. A relatively deficient immune responsiveness may allow progression to more severe and generalized disease (RPP). Suggestions are made for studies needed to confirm suspected pathogenetic mechanisms, approach resultant targeted therapies, and test hypotheses for contrasting roles of immune reactions in different clinical expressions of periodontitis.

Salivary defense mechanisms in juvenile periodontitis

The local, saliva-associated defense mechanisms of 28 juvenile periodontitis (JP) patients and their age- and sex-matched controls were studied. Lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, and thiocyanate concentrations were determined from both whole saliva and parotid saliva. The total concentrations of salivary IgA, IgG, and IgM were assayed. The periodontal condition and the salivary flow rates were registered. Among the JP patients, a significantly elevated concentration of IgG was found in parotid saliva but not in whole saliva. Salivary peroxidase activities were significantly low both in the whole and in the parotid saliva samples of the JP patients, and leukocyte-derived myeloperoxidase was present in significantly low amounts in whole saliva of these patients. Because both glandular (salivary peroxidase) and polymorphonuclear-cell-derived (myeloperoxidase) enzyme activities were low among the JP patients, suppressed peroxidase-mediated host defense mechanisms could be characteristic of JP.

Genetic approaches in the study of periodontal diseases

Periodontal diseases are essentially infectious in origin, their outcome depending on interaction between the pathogenic challenge and host response. Host genotype has been implicated in certain of the more unusual forms, but together these account for only a small proportion of periodontal patients. Nevertheless, the genes for these rarer conditions, some of which have already been located and/or cloned, are of considerable importance, since they may ultimately provide clues leading to a better understanding of the whole spectrum of periodontal disease. For the majority of periodontal patients, although inherited susceptibility is suspected, evidence of a significant genetic component is scanty. The priority here is therefore to establish the existence of contributing genes. This may be possible by using approaches designed to minimise the confounding effect of environmental variation that has probably been a source of confusion in the past.

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The growth in the dental literature continues to escalate, as evidenced by the publication of at least 326 new books in 1988 and 1989 and more than 20 new journals in 1989. There still appears to be undue emphasis on quantity instead of quality of research. This proliferation in the literature poses ever increasing difficulties to this Committee in filtering out the articles that are of particular interest to the members of the Academy and identifying those that are most likely to have a major impact on dental practice and service. The subjects covered include periodontics, caries and preventive dentistry, craniomandibular disorders, occlusion, pulp biology, ceramics, and restorative dental materials.

Phagocyte function in juvenile periodontitis

We studied the chemotaxis of peripheral blood polymorphonuclear leukocytes (PMNs) and monocytes and the production of tumor necrosis factor alpha by monocytes of patients with juvenile periodontitis (JP). As a group, the patients' PMNs showed significantly increased chemotaxis determined by counting the number of migrating cells within a 3-microns-pore-size filter. Determined as distance of migration within the filter, as chemotactic increment based on checkerboard analysis, as leukotactic index calculated on the basis of distance of migration and cell count at different depths within a 3-microns-pore-size filter, as distance of migration under agarose, and as the number of PMNs migrating across a 5-microns-pore-size filter, the chemotactic migration rates of PMNs of patients were similar to those of controls. Evaluation of the data on an individual basis suggested that in terms of PMN chemotaxis some patients were hyperresponsive and some were hyporesponsive. Chemotaxis, spontaneous migration, and the rates of lipopolysaccharide-induced tumor necrosis factor alpha production by JP monocytes were similar to those of control cells. Our results give credence to the view that there are minor aberrations in the functions of JP phagocytes, but the extent to which these aberrations are relevant to accumulation of PMNs at sites of infection and inflammation in vivo and possibly contribute to the pathogenesis of JP remains unclear.

An in vivo study of neutrophil locomotion in relation to periodontal disease status and local chlorhexidine

Neutrophil migration from skin window abrasions was studied in 10 patients with no history of periodontitis, 10 with localised juvenile or post-juvenile periodontitis, and 10 with chronic adult periodontitis. Filters contained either saline or chlorhexidine (0.002% or 0.02%). The leading front was measured in filters placed for 30 min after cell migration had been established for 2 h. Subjects in the juvenile/post juvenile group showed a reduced range of migration distances, but were still within the normal range when compared with the other 2 groups. Chlorhexidine at 0.002% tended to increase leading front distances, and 0.02% to decrease them. We conclude that: 1) migrating neutrophils in vivo may move less far in patients with a history of juvenile periodontitis; 2) chlorhexidine may inhibit cell migration, possibly decreasing the host response in vivo if applied at current therapeutic concentrations.

Effects of chlorhexidine solution on neutrophil locomotion in vitro

The aim of this study was to ascertain the effect of low concentrations of chlorhexidine on the locomotor behaviour of neutrophils. A special feature was the use of a direct test of chemotaxis. Neutrophils recovered from peripheral blood of healthy adult volunteers were tested for chemokinesis and chemotaxis in the presence of chlorhexidine. A moderate dose-related direct response was observed in respect of both these parameters. It was also apparent that increasing concentrations of the drug inhibited a greater proportion of cells, so that there was total immobility at 0.2 per cent and many cells appeared lysed.