Table 2.

Pattern recognition receptors and the inflammatory response of chorioamnionitis.

Pattern Recognition Receptor	Associated Inflammatory Response
TLR-2	Plays a major role in Gram-positive bacterial recognition. TLR2 hetero-dimerizes with either TLR-1 or TLR-6 and these dimers recognize constituents of Gram-positive bacteria such as peptidoglycan (PGN), and lipoteichoic acid (LTA) [22,25].
TLR-3	Involved in the response to viral infection by recognizing double-stranded RNA [22,25].
TLR-4	Recognizes Gram-negative lipopolysaccharide [22,25].
NOD-2	Recognizes muramyl dipeptide (MDP) which is found in peptidoglycan of both Gram-negative and Gram-positive bacteria [26].
MCP-1	Recruitment of monocytes/macrophages to inflammatory sites [27].
IL-1ß	Increases expression of neutrophil chemotactic and activating chemokines as well enhances MMP expression IL-1β also increases the production of cyclooxygenase (COX)-2 and prostaglandin E2 (PGE2) [28,29].
TNF-α	Produced primarily by macrophages and T cells, a potent proinflammatory cytokine which promotes vasodilation, oedema, leukocyte adhesion and indirectly induces fever [30].
IL-6	Activates T cells and natural killer cells; increases the expression of oxytocin receptors on myometrial cells and oxytocin secretion by myometrial cells [29]
IL-8	Recruits neutrophils; cervical remodeling and rupture of the gestational membrane [31].
MMP	Promotes preterm delivery via decidual, gestational membrane, and cervical extracellular matrix degradation [32].
PGE2	Increases intracellular calcium concentrations in myometrial cells and works synergistically with IL-8 in cervical ripening [32,33].