Virulence factors of Actinobacillus actinomycetemcomitans relevant to the pathogenesis of inflammatory periodontal diseases

Abstract

There is strong evidence implicating Actinobacillus actinomycetemcomitans as the causative agent of localised juvenile periodontitis (LJP), a disease characterised by rapid destruction of the tooth-supporting tissues. This organism possesses a large number of virulence factors with a wide range of activities which enable it to colonise the oral cavity, invade periodontal tissues, evade host defences, initiate connective tissue destruction and interfere with tissue repair. Adhesion to epithelial and tooth surfaces is dependent on the presence of surface proteins and structures such as microvesicles and fimbriae. Invasion has been demonstrated in vivo and in vitro although the mechanisms involved are poorly understood. The organism has a number of means of evading host defences which include: (i) inhibiting poloymorphonuclear leukocyte (PMN) chemotaxis; (ii) killing PMNs and monocytes; (iii) producing immunosuppressive factors; (iv) secreting proteases capable of cleaving IgG; and (v) producing Fc-binding proteins. Surface components of A. actinomycetemcomitans are potent stimulators of bone resorption and can induce the release of a range of cytokines which can initiate tissue destruction. A number of surface components can also inhibit the proliferation of fibroblasts and their production of components of the extracellular matrix. Little is known, however, regarding the way in which these factors operate in vivo to produce the pathological features of the disease.

Occurrence of Aggregatibacter actinomycetemcomitans in Brazilians with chronic periodontitis

“…[3][4][5][6][7][8][9][10] This bacterium expresses several putative virulence factors which enable it to colonize the oral cavity, invade periodontal tissues and evade host defenses. 11 Additionally, different serotypes of A. actinomycetemcomitans have been shown to be associated with periodontal health and disease. 12,13 Chronic periodontitis may begin in adolescence as a slowly progressing disease that becomes clinically significant in the mid-30 s and continues throughout life.…”

The role of macrophages in the induction of murine immune response to Actinobacillus actinomycetemcomitans

“…Actinobacillus actinomycetemcomitans is a gramnegative bacterium that is regarded as a member of the microflora of dental plaque and, therefore, may play a role in chronic inflammatory periodontal disease (CIPD) [1,2]. Evidence has shown that the numbers of this micro-organism are increased in patients with periodontal disease, especially those with early-onset periodontitis [3][4][5][6].…”

Actinobacillus actinomycetemcomitans Cytolethal Distending Toxin (Cdt): Evidence That the Holotoxin Is Composed of Three Subunits: CdtA, CdtB, and CdtC

“…These include endocarditis, meningitis, osteomyelitis, s.c. abscesses, endophthalmitis, and periodontal disease (1)(2)(3)(4)(5)(6)(7). Although the pathogenic mechanism(s) by which A. actinomycetemcomitans acts to cause disease is not known, it has been shown to produce several potential virulence factors capable of facilitating colonization, destroying host tissue, inhibiting tissue repair, and interfering with host defenses (reviewed in Ref.…”