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Foods Food Ingredients J. Jpn., Vol. 210, No.4, 2005  

Pa th ogenesis an d Symptoms of Hu ma n P eriodont al Diseases

Shigenobu KimuraDepartment of Oral Microbiology, Iwate Medical University School of Dentistry

1-3-27, Chu odori, m orioka-shi, Iwa te 020-8505, J apa n

Summary

Although periodontal diseases are initiated by oral bacteria, it is also evident that the host

response plays a ma jor r ole in th e out come of th ese infections. This review addressed t hose un ique

host-para site intera ctions in t he pat hogenesis and sympt oms of human periodont al diseases.

Early studies on the pathogenic potential of plaque bacteria incriminated some selected

gram-negative organisms (periodontopathogens), especially Porphyromonas gingivalis  and

Actinobacillus actinomycetemcomitans  as major pathogens of adult and juvenile periodontitis,

respectively. However, our cross-sectional study in periodontally healthy children indicated the

colonizat ion of ma ny pu ta tive periodont opath ogens (with out clinical signs of periodont al disea se)

against the host defense mechan ism by saliva. Thus, it is possible th at th e saliva a s a host defense

mechan ism could in hibit more effectively the proliferat ion of colonized pat hogens t ha n th e initia l

colonization of organisms to gingival crevices. The polymorphonuclear leucocyte (PMNL) that is

the predominant cell of the gingival crevicular and pocket exudates acts as another host defense

mechan ism in gingival crevices. Substant ial reports indicat ed th at patients with P MNL disorders

have unusually rapid and severe periodontitis. We previously demonstrated that about 50% of the

pat ients wit h localized juvenile and gener alized juvenile periodontitis, but not a dult periodont itis,

exhibited depression of phagocytic function of the peripheral blood PMNL. Therefore, defective

PMNL function could be implicated in the pathogenesis of periodontitis, especially in juvenile

periodontitis.

The colonized periodont opat hogens could in vade/penetra te t he epith elial cells into gingival t issues.

In gingival tissues, the evasive action by the virulent components, such as lipopolysaccharide

(LPS) and proteases, of periodontopathogens against host defense mechanisms might be crucial

steps in leading tissue destruction and alveolar bone resorption. We indicated the unique

activation pathways of B cells by P. gingivalis  LPS and the impairment in regulatory T cell

fun ction in adu lt periodont itis. Fur th er, th e alter at ion in r egulat ory T cell fun ction could be relat ed

to senescence.

The precise basis for the host-parasite interaction is still not understood, however, evidence

indicates th e cent ra l role of th e relationsh ip between the host defense mecha nism a nd virulence of 

periodont al pat hogens in initiat ion an d development of periodont al diseases.

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Foods Food Ingredients J. Jpn., Vol. 210, No.4, 2005