Oral Microbial Ecology and the Role of Salivary Immunoglobulin A

Abstract

SUMMARY In the oral cavity, indigenous bacteria are often associated with two major oral diseases, caries and periodontal diseases. These diseases seem to appear following an inbalance in the oral resident microbiota, leading to the emergence of potentially pathogenic bacteria. To define the process involved in caries and periodontal diseases, it is necessary to understand the ecology of the oral cavity and to identify the factors responsible for the transition of the oral microbiota from a commensal to a pathogenic relationship with the host. The regulatory forces influencing the oral ecosystem can be divided into three major categories: host related, microbe related, and external factors. Among host factors, secretory immunoglobulin A (SIgA) constitutes the main specific immune defense mechanism in saliva and may play an important role in the homeostasis of the oral microbiota. Naturally occurring SIgA antibodies that are reactive against a variety of indigenous bacteria are detectable in saliva. These antibodies may control the oral microbiota by reducing the adherence of bacteria to the oral mucosa and teeth. It is thought that protection against bacterial etiologic agents of caries and periodontal diseases could be conferred by the induction of SIgA antibodies via the stimulation of the mucosal immune system. However, elucidation of the role of the SIgA immune system in controlling the oral indigenous microbiota is a prerequisite for the development of effective vaccines against these diseases. The role of SIgA antibodies in the acquisition and the regulation of the indigenous microbiota is still controversial. Our review discusses the importance of SIgA among the multiple factors that control the oral microbiota. It describes the oral ecosystems, the principal factors that may control the oral microbiota, a basic knowledge of the secretory immune system, the biological functions of SIgA, and, finally, experiments related to the role of SIgA in oral microbial ecology.

Comparison of immunological and microbiological characteristics in children and the elderly with or without dental caries

“…Among the several factors leading to dental caries, S. mutans, one species of cariogenic bacteria, is widely accepted as a primary causative agent (5). Salivary sIgA is the first line of defence of the host against pathogens invading oral mucosal surfaces, which could help oral immunity by preventing microbial adherence and by neutralizing enzymes, toxins, and viruses (8,26). In the present study we compared the quantity of S. mutans in saliva and the concentrations of total salivary sIgA and specific sIgA against two virulence antigens of S. mutans in two susceptible populationschildren and the elderlyunder different caries status, and assessed the relationships between ECC or RC and S. mutans levels and salivary sIgA.…”

Oral microflora in infants delivered vaginally and by caesarean section

“…The selected groups were also found to be well balanced concerning the background factors except for the fact that more parents in the C-section group reported domestic tobacco smoke. It is well known that biological as well as several lifestyle factors such as smoking, diet, and hygiene may influence the composition of the oral microflora 17,18 . It should, however, be underlined that the absolute number of smoking parents was fairly low also in the C-section group (n = 6).…”

Repeated evolutionary transitions of flavobacteria from marine to non‐marine habitats

“…S1I). Peptidases in the M64 family enable the pathogens to cope with antimicrobial agents such as IgA that are often contained in host-derived saliva when hosts are challenged by pathogens (Marcotte and Lavoie, 1998). A second example is the family S46 (dipeptidyl aminopeptidases) involved in digesting oligopeptides at the periplasm (Sakamoto et al, 2014) in some bacterial pathogens such as Porphyromonas gingivalis (Bostanci and Belibasakis, 2012) and Stenotrophomonas maltophilia (Brooke, 2012).…”