43 It remains to be determined which recovery technique (CVL, tampon, or swab) most accurately reflects antimicrobial levels in the lower FRT. Whether upper FRT secretions, which contain elevated levels of antimicrobials at mid-cycle, mix with vaginal fluid to mask cycle-dependent differences remains to be determined. Furthermore,

it is important to accurately identify the cycle stage from which samples are recovered. Thus, self-reporting based upon the idealized 28-day cycle, while useful in some cases, can be replaced by direct measurement of serum estradiol and progesterone. Within the upper FRT, HBD1–4 mRNA levels peak in endometrial tissue at different times during the menstrual cycle with HBD4 highest during the proliferative phase and HBD2 peaking at menstruation. Similar to HBD2, Elafin increases late in the cycle,44 while HBD1 is highest during the

mid-secretory stage. In buy RAD001 contrast, HBD3 is maximal at early and late secretory, with a transient decline at mid-secretory. SLPI mRNA and protein also peak during the secretory phase.45 In the Fallopian tube, SLPI and Elafin mRNA expression remain constant across the cycle.46 The reason behind this exquisite regulation of upper FRT antimicrobial expression may reside either in their unique antimicrobial activities or in non-antimicrobial functions related to fertility that remain to be determined. Over 90% of sexually active women in the United States have used some form of contraception at least once.47 Given its widespread use, the effect of hormonal click here contraceptives on antimicrobial levels is understudied. In a seminal study, Schumacher48 demonstrated that sequential oral contraceptives suppress the cyclic changes of a spectrum of proteins including IgG, IgA, and lysozyme. In other studies with a combination oral contraceptive, no effect on antimicrobial expression 2-hydroxyphytanoyl-CoA lyase was observed except for a significant decrease in HBD3 when compared to the secretory phase.49 In the upper FRT, women taking the combined oral contraceptive had decreased SLPI in

luminal epithelial secretions compared to women in the proliferative phase.50 Future studies need to separate the different classes of oral contraceptives to determine their effects on the innate immune system throughout the FRT. Traditionally, pregnancy has been defined as a general state of immune suppression. However, this notion has been challenged recently with an evolution of our understanding; pregnancy seems to be both a pro-inflammatory and an anti-inflammatory state depending on the stage of gestation (reviewed by Ref. 51). The trophoblast, which is the cellular unit of the placenta, acts as an immune-regulatory interface between the maternal and fetal units. The placenta can recognize microorganisms and initiate response by producing cytokines, chemokines, and antimicrobials. Specifically, trophoblastic cells have been shown to produce HBDs, SLPI, and IFNβ in response to pathogenic stimuli.