Role of Cytokines, Endotoxins (LPS), and Lipoteichoic Acid (LTA) in Endodontic Infection

Abstract

The most common etiological factor for pulpal and periapical disease is microorganisms. Apical periodontitis is considered as an inflammatory reaction in the peri-apical tissues to the presence of micro-flora and their components within the root canal system. The composition of micro-flora of root canal has been studied extensively over the years and the presence of gram-positive, gramnegative bacteria and their components are considered to be the main reason for endodontic treatment failure. Bacterial components such as Lipopolysaccharide (LPS) and Lipoteichoic Acid (LTA) can enter the peri-apical tissue and initiate the inflammatory process by increasing the level of cytokines. Therefore, this review was done to understand the role of Lipopolysaccharide (LPS), Lipoteichoic acid (LTA) and cytokines in endodontic infection and study their relationship between each other. Data from various resources were gathered and analyzed. The activation pathway and biological effects of cytokines were also studied and it was observed that cytokines especially TNF-α (Tumour Necrosis Factor), IL-1β (Interleukin), IL-6 and IL-8 are up-regulated as a consequence of the immune response generated against the LPS and LTA. Chemokines CXCL2 (Chemokine (C-X-C motif) ligand) and CXCL10 were also shown to have increased level due to the presence of LTA. Cytokines are required to combat the foreign material during an infection, but when the level of cytokines is too high, it can cause injuries to the host itself through peri-apical bone destruction. More studies should be carried out in order to better understand the significance of each cytokine during an endodontic infection and to improve the treatment given for the patients depending on their infection status.