Salivary lactoferrin and low-M-r mucin MG2 in Actinobacillus actinomycetemcomitans-associated periodontitis

Concentrations and output of lactoferrin and of low-M-r mucin MG2 were dete rmined in saliva of subjects suffering from Actinobacillus actinomycetem-co mitans-associated periodontal disease and healthy subjects. Periodontal pat ients were clinically examined and a microbiological sample was taken from the deepest bleeding pockets in each quadrant. The number of viable A. acti nomycetemcomitans was determined in the sampled sites of each patient. The MG2 output in the diseased subjects (13.6 mu g protein/min) was decreased a t least by a factor three compared to periodontal healthy subjects (44.3 mu g protein/min). On the other hand, output of lactoferrin was not significa ntly different in healthy (9.5 mu g/min) and diseased subjects (7.6 mu g/mi n). Western analyses demonstrated a higher iron-saturation of lactoferrin i n diseased subjects in comparison with the healthy subjects. Lactoferrin de grading enzymes, probably derived from microbial sources, could be detected in saliva of the periodontally diseased subjects, but not in saliva of hea lthy subjects. The combination of iron-saturation and degradation of lactof errin suggests that anti-microbial properties of lactoferrin are diminished in periodontitis patients. Moreover, the low concentration of mucin MG2 su ggests a decline in mucin defence and consequently a higher susceptibility for oral infection. A negative correlation (r = -0.4, p< 0.05) between the number of subgingival A. actinomycetemcomitans and lactoferrin in saliva su ggested that low concentrations of lactoferrin favour the growth of the bac terium. These data indicate that a decline in the salivary defence system m ight increase the risk for oral infection by A. actinomycetemcomitans.