Osteoimmunology and Microbial Load of Periimplant Tissues

The search of a link between the cytokine levels and the specific bacterial pathogens is the subject of new studies in osteoimmunology. Bacteria impact similar responses to the host, causing the characteristic effects of signaling pathways associated with a series of proinflammatory cytokines. Conditions provided by the host in the mouth affect the development, composition and metabolic activity of the oral microflora and vary in different areas of the oral cavity. Analogous to this, the composition of the oral microflora varies in different ecosystems: tongue, buccal mucosa and teeth. When the microorganisms are in “health status” they are in dynamic equilibrium with the host, but change in the key parameters that determine microbial growth can disturb equilibrium. In order to better understand the link between oral microorganisms and the host in the state of health or disease, a concept is developed which is based on ecological principles that explain their interactions. The ecological plaque hypothesis describes the dynamic nature of the relationship between the host and the normal microflora [1]. Changes in the environment increase the competitiveness of pathogens and increase the virulence factors. Pathogenic microorganisms may also be present in a good health condition of the oral tissues, but with extremely low representation and clinically unsignificant levels. According to this hypothesis, there is a direct link between local environmental conditions and activity and composition of the biofilm. The local environmental conditions also involve temperature, redox potential, nutrients, genetic characteristics, lifestyle and the age of the host. Thanks to innate and acquired immunity, the host prevents bacterial invasion and colonization. But despite immune defense, the host developed capabilities to support complex microflora. Receptors for host cell recognition (host cell pattern recognition receptors-PRPs) are deployed strategically in tissues to register changes in the external and internal microenvironment and recognize microbe-associated molecular pathways (microbe-associated molecular patterns MAMPs) such as lipopolysaccharides, nucleic acids, etc. They are able to activate multiple signaling pathways in which most of them are cross through nuclear factor (NF-kB). MAMPs get rid of all microbial cells. Host created mechanisms for tolerance of resident microorganisms in order not to initiate harmful inflammatory responses, but does not lose the ability to effectively defend against pathogens [2]. The importance of systems for detection of host manifested by the fact that abnormal expression of PRPs that bind bacterial lipopolysaccharide (TLR2 and CD14) is associated with predisposition to the development of diseases of the anchor apparatus [3]. Resident oral bacteria determine the normal expression of immune mediators, assist in maintaining the health of tissues through regulation of low levels of expression of intracellular adhesion molecules (intracellular adhesion molecule-1), E-selectin, IL-8, which in turn participate in the creation of a protective layer of neurofili strategically positioned between subgingival biofilm and the attached epithelium [4].