Serum Antibody Opsonic Activity against Actinobacillus actinomycetemcomitans in Human Periodontal Diseases

1993 ◽  
Vol 168 (6) ◽  
pp. 1436-1443 ◽  
Author(s):  
K. Underwood ◽  
K. Sjostrom ◽  
R. Darveau ◽  
R. Lamont ◽  
H. Schenkein ◽  
...  
Keyword(s):  
Periodontal Diseases ◽  
Serum Antibody ◽  
Actinobacillus Actinomycetemcomitans ◽  
Opsonic Activity

scholarly journals Caspase 1 Involvement in Human Monocyte Lysis Induced by Actinobacillus actinomycetemcomitans Leukotoxin

2003 ◽  
Vol 71 (8) ◽  
pp. 4448-4455 ◽  
Author(s):  
P. Kelk ◽  
A. Johansson ◽  
R. Claesson ◽  
L. Hänström ◽  
S. Kalfas
Keyword(s):  
Periodontal Diseases ◽  
Human Monocyte ◽  
Actinobacillus Actinomycetemcomitans ◽  
Lymphocyte Function ◽  
Human Leukocytes ◽  
Caspase 1 ◽  
Oral Bacterium ◽  
Toxin Exposure ◽  
Apoptotic Activity ◽  
Leukocyte Populations

ABSTRACT Actinobacillus actinomycetemcomitans, an oral bacterium implicated in the etiology of periodontal diseases, produces a leukotoxin that selectively lyses primate neutrophils and monocytes, the major populations of defense cells in the periodontium. Though lysis requires expression of the receptor lymphocyte function-associated molecule 1 (LFA-1) on the cell surface, not all LFA-1-expressing leukocyte populations are equally susceptible to the toxin. In this study, the susceptibility of human leukocytes to leukotoxin-induced lysis is compared to their expression of LFA-1 and the activity of caspase 1. Cytolysis was determined by the activity of lactate dehydrogenase released from peripheral human leukocytes after 1-h exposure to leukotoxin. Monocytes were lysed at leukotoxin concentrations of ≥5 ng/ml, while the corresponding values for neutrophils and lymphocytes were approximately 10 times greater. Similar LFA-1 expression was found in all susceptible cell populations irrespective of their degree of sensitivity to the toxin. Exposure of monocytes to leukotoxin increased their caspase 1 activity about fivefold within 10 to 20 min. Presence of the caspase 1 inhibitor Ac-YVAD-CMK significantly blocked the leukotoxin-induced lysis of monocytes only. At sublytic concentrations, leukotoxin induced no apoptotic activity in monocytes, as revealed by the lack of caspase 3 activation and DNA fragmentation. Monocytes are the most lysis-sensitive leukocytes for A. actinomycetemcomitans leukotoxin. Their lysis by this toxin depends on caspase 1 activation and proceeds through a process that differs from classical apoptosis.

scholarly journals Beyond the Specific Plaque Hypothesis: Are Highly Leukotoxic Strains of Actinobacillus Actinomycetemcomitans a Paradigm for Periodontal Pathogenesis?

2001 ◽  
Vol 12 (2) ◽  
pp. 116-124 ◽  
Author(s):  
J.M. Guthmiller ◽  
E.T. Lolly ◽  
J. Korostoff
Keyword(s):  
Virulence Factors ◽  
Periodontal Diseases ◽  
Actinobacillus Actinomycetemcomitans ◽  
Pathogenic Potential ◽  
Periodontal Bacteria ◽  
Genes Encoding ◽  
Localized Juvenile Periodontitis ◽  
Different Populations

Actinobacillus actinomycetemcomitans is a facultative anaerobe implicated in a variety of periodontal diseases. Its presence is most closely associated with localized juvenile periodontitis (LJP), although the exact role of the organism in this and other periodontal diseases is not entirely clear. While A. actinomycetemcomitans produces several different putative virulence factors, the most widely studied is the leukotoxin. The leukotoxin selectively kills polymorphonuclear leukocytes and macrophages in vitro, constituting the host's first line of defense. Interestingly, even though all strains of A. actinomycetemcomitans have the genes encoding the leukotoxin, there is variability in leukotoxin expression. Differences in the structure of the promoter region of the leukotoxin gene operon were shown to correlate directly with levels of leukotoxin production. Highly leukotoxic forms appear to exhibit increased pathogenic potential, as evidenced by recent studies that have shown a significant association between the prevalence of such strains and the occurrence of LJP in several different populations. This represents the first demonstration of an association between a particular subset of a pathogenic species and a specific periodontal disease. Early identification of A. actinomycetemcomitans by microbial and genetic assays to evaluate leukotoxicity may enhance the efficacy of preventive and/or therapeutic techniques. Future investigations should continue to evaluate pathogenic variations of additional virulence factors expressed in vivo, not only of A. actinomycetemcomitans, but also of other periodontal bacteria and infectious disease pathogens.

scholarly journals Interdental Supragingival Plaque—A Natural Habitat of Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, and Prevotella nigrescens

1994 ◽  
Vol 73 (8) ◽  
pp. 1421-1428 ◽  
Author(s):  
R. Gmur ◽  
B. Guggenheim
Keyword(s):  
Periodontal Diseases ◽  
Natural Habitat ◽  
Minor Component ◽  
Actinobacillus Actinomycetemcomitans ◽  
Periodontal Pathogens ◽  
Campylobacter Rectus ◽  
Prevotella Nigrescens ◽  
Supragingival Plaque ◽  
Three Samples ◽  
A Minor

The aim of this study was to test the hypothesis that suspected periodontal pathogens form a minor component of the supragingival plaque of individuals without periodontal diseases. Twenty-one dental hygienist trainees with a mean age of 23.5 years were twice sampled for interdental plaque between 1st and 2nd molars in all quadrants. The samples were assessed for Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, Porphyromonas gingivalis, and the Prevotella intermedia/Prevotella nigrescens group of organisms. Bacteria of this group were predominantly P. nigrescens and showed both the highest prevalence (100%) and the highest colonization density of the investigated species. Seven of 21 samples harbored A. actinomycetemcomitans. Serotypes a, b, and c were found in three samples each, while serotype e was present in one sample. Three subjects had two different A. actinomycetemcomitans serotypes. Bacteroides forsythus and C. rectus were detected in 10 (48%) and nine (43%) subjects, respectively. The detected cell numbers accounted for approximately 0.01% to 1% of the sampled flora. In contrast, P. gingivalis was found only in a single sample, which in addition harbored B. forsythus, C. rectus, A. actinomycetemcomitans (serotypes b and e), and P. intermedia. These results suggest that the investigated periodontal bacteria are not "exogenous pathogens", but amphibiotic, opportunistic microorganisms which may have a natural habitat in the supragingival plaque of the interproximal area of molars.

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