Avidity of antibody responses to Actinobacillus actinomycetemcomitans in periodontitis

Myricetin blocks lipoteichoic acid-induced COX-2 expression in human gingival fibroblasts

Periodontitis is an infectious disease caused by microorganisms present in dental bacterial plaque. Lipoteichoic acid (LTA) is a component of the external membrane of Gram-positive bacteria. It causes septic shock. Ingested flavonoids have been reported to directly affect the regulation of cyclooxygenase-2 (COX-2) expression induced by bacterial toxins. In this study, we examined the effects of four flavonoids (luteolin, fisetin, morin and myricetin) on the activation of ERK1/2, p38 and AKT, and on the synthesis of COX-2 in human gingival fibroblasts treated with LTA from Streptococcus sanguinis. We found that luteolin and myricetin blocked AKT and p38 activation and that myricetin blocked LTA-induced COX-2 expression. The results of our study are important for elucidating the mechanism of action of flavonoid regulation of inflammatory responses.

Quadrant root planing versus same-day full-mouth root planing. III. Dynamics of the immune response

OBJECTIVES

The aim of this study was to determine whether same-day full-mouth scaling and root planing (FM-SRP) and quadrant scaling and root planing (Q-SRP) resulted in variations in the systemic humoral immune response dynamics (antibody titres and avidity) during active treatment and 3 and 6 months post-therapy.

MATERIALS AND METHODS

Forty patients with chronic periodontitis were recruited into this study. Subjects were randomised into two groups and received either scaling and root planing quadrant by quadrant at 2-weekly intervals (Q-SRP group) or same-day full-mouth scaling and root planing (FM-SRP group). Clinical measurements and serum samples were obtained at baseline and approximately 6 weeks after the last clinical intervention (R1) and 6 months after the initiation of therapy (R2). Furthermore, serum samples were obtained from each patient undergoing therapy (Q-SRP and FM-SRP) at 3 bi-weekly instances so as to determine the short-term effects of each session of scaling and root planing on the dynamics of the humoral immune response. Serum antibody titre was assayed by enzyme-linked immunosorbent assay (ELISA) and antibody avidity was measured by thiocyanate dissociation against five putative periodontal pathogens: Porphyromonas gingivalis; Actinobacillus actinomycetemcomitans; Prevotella intermedia; Treponema denticola and Bacteroides forsythus.

RESULTS

Both therapies resulted in similar antibody titre reductions against the majority of the organisms tested and although there was a distinct trend for antibody avidity to increase following therapy, this was not found to be statistically significant, reflecting marked inter-individual variation. In addition, no evidence emerged from this study to support increased antibody titres following the active phases of both treatment approaches due to an inoculation effect. Nevertheless, significant short-term increases in antibody avidity to most test bacteria were noted for both treatment strategies.

CONCLUSION

Both therapies were associated with a reduction in antibody titres and an increase in the binding ability or avidity of antibodies, but there was a marked inter-subject variability and statistical significance was reached for only some of the test bacteria. No significant differences in the humoral antibody dynamics were found between the two treatment approaches.

Longitudinal changes in antibody avidity to Actinobacillus actinomycetemcomitans in periodontitis

Longitudinal investigations concerning immunological responses and periodontal disease activity support a relationship between serum antibody levels and the micro-organisms associated with dental plaque. To define this host response further, we studied the relationship of antibody avidity to Actinobacillus actinomycetemcomitans (Aa) in 11 adult periodontitis and 6 localized juvenile periodontitis (LJP) patients with Aa infections. Patients were monitored every 3-4 months for immunological and clinical variables including probing pocket depths (PD), bleeding on probing (BOP), plaque index (PLI), and the number of disease active sites (DA). Avidity indices were determined using an ELISA and significant changes from each patients' baseline level were determined. The results showed different response patterns between and within the patient groups. A subset of the subjects experienced significant changes in antibody avidity over time. Between group comparisons yielded no significant differences in the number of positive or negative avidity index changes, although there were more frequent changes in the disease active adult periodontitis group. There were also no significant correlations between clinical parameters and antibody avidity, although there were changes in the clinical parameters between baseline and significant avidity change points, and also between baseline and the determination of active disease. Further studies will be necessary to define fully the role of antibody avidity and its relationship to the pathogenesis of periodontal diseases.