The Role of Toll Like Receptors in Pregnancy

Abstract

For many years, the innate immunity was of less interest than the adaptive immunitybecause it was perceived to have secondary importance in the functionality of theimmune system. During the past decades, with the advancement of knowledge aboutinnate immune system, interest in innate immunity has grown dramatically and thusits function has been extensively studied. Innate immunity plays fundamental rolesin the initiation and induction of adaptive immune responses. It consists of severalcells and receptors including natural killer (NK) cells, macrophages (MQs), dendriticcells (DCs) and pattern recognition receptors (PRRs). Two decades ago, Tolllike receptors (TLRs) family was known as one of the important PRRs with uniquefunctions especially in protection against invading pathogens. Since the female reproductivetract has access to the outside environment and has a unique interactionwith different pathogens whether invading microorganisms or normal flora, allogenicsperm and semi allogenic fetus, it has an essential need for effective immuneresponses. It has therefore been suggested that TLRs may play important roles inthe immune regulation of the female reproductive tract. In addition, it has beendemonstrated that immune disturbance may be responsible for some adverse pregnancyoutcomes such as preeclampsia (PE), recurrent spontaneous abortion (RSA)and intrauterine growth restriction (IUGR). Our focus in this review is to show theimportance of TLRs in pregnancy with emphasis on the expression of these receptorsin different tissues related to pregnancy.