Endometrial NK Cell Subpopulations CD16−CD56Brightand CD16−CD56Dimin Women with Recurrent Implantation Failure

Endometrial microbes and microbiome: Recent insights on the inflammatory and immune "players" of the human endometrium

In recent years, extended scientific works shed light on the important role played by the endometrium in early pregnancy. This review examines our current knowledge about the delicate balance between microbial and cellular immune agents at endometrial level: All of them might affect endometrial receptivity. In contrast to the classical thinking of human endometrium as a sterile tissue, several recent studies have drawn attention to a resident population of microorganisms, which reaches only a 30% of concordance with those of the cervical-vaginal flora. At present, the understanding of the microbiome in relation to human reproduction is in its infancy and further studies are needed to clarify the activity of endometrial microbiome and the possible effects of a "reproductive tract dysbiosis" on fertility. Moreover, in the human endometrium, there is a complex system works preventing the risk of infection as well as enabling, when pregnancy occurs, the acceptance of the blastocyst. In this way, the endometrium plays a central role in the uterine immune surveillance. A better understanding of the different agents that may affect endometrial receptivity would improve the diagnosis and treatment of obstetric complications related to defective implantation and placentation.

Porphyromonas gingivalis and adverse pregnancy outcome

Porphyromonas gingivalis is a Gram-negative, anaerobic bacterium considered to be an important pathogen of periodontal disease that is also implicated in adverse pregnancy outcome (APO). Until recently, our understanding of the role of P. gingivalis in APO has been limited and sometimes contradictory. The purpose of this review is to provide an overview of past and current research on P. gingivalis that addresses some of the controversies concerning the role of this organism in the pathogenesis of APO.