Anne E. King

Innate immune defences in the human endometrium

The human endometrium is an important site of innate immune defence, giving protection against uterine infection. Such protection is critical to successful implantation and pregnancy. Infection is a major cause of preterm birth and can also cause infertility and ectopic pregnancy. Natural anti-microbial peptides are key mediators of the innate immune system. These peptides, between them, have anti-bacterial, anti-fungal and anti-viral activity and are expressed at epithelial surfaces throughout the female genital tract. Two families of natural anti-microbials, the defensins and the whey acidic protein (WAP) motif proteins, appear to be prominent in endometrium. The human endometrial epithelium expresses beta-defensins 1–4 and the WAP motif protein, secretory leukocyte protease inhibitor. Each beta-defensin has a different expression profile in relation to the stage of the menstrual cycle, providing potential protection throughout the cycle. Secretory leukocyte protease inhibitor is expressed during the secretory phase of the cycle and has a range of possible roles including anti-protease and anti-microbial activity as well as having effects on epithelial cell growth. The leukocyte populations in the endometrium are also a source of anti-microbial production. Neutrophils are a particularly rich source of alpha-defensins, lactoferrin, lysozyme and the WAP motif protein, elafin. The presence of neutrophils during menstruation will enhance anti-microbial protection at a time when the epithelial barrier is disrupted. Several other anti-microbials including the natural killer cell product, granulysin, are likely to have a role in endometrium. The sequential production of natural anti-microbial peptides by the endometrium throughout the menstrual cycle and at other sites in the female genital tract will offer protection from many pathogens, including those that are sexually transmitted.

Fibroblast Heterogeneity : Existence of Functionally Distinct Thy 1+ and Thy 1− Human Female Reproductive Tract Fibroblasts

Little is known about fibroblasts from the female reproductive tract, much less whether or not functional subsets exist. Fibroblasts are key as sentinel cells for recruiting white blood cells and for wound healing. The purpose of this research was to evaluate the possibility that functional subsets of fibroblasts exist in the human female reproductive tract. The strategy used was to define fibroblast subpopulations based on their surface expression of the Thy 1 antigen. In situ staining of human myometrium and endometrium showed heterogeneous staining for Thy 1. Freshly derived strains of fibroblasts from the myometrium and endometrium also demonstrated heterogeneous Thy 1 expression. For the first time, using magnetic beading and fluorescence-activated cell sorting, human myometrial fibroblasts were successfully separated into functionally unique Thy 1(+) and Thy 1(-) subsets. Both subsets produced the proinflammatory cytokines interleukin (IL)-6 and IL-8 after IL-1beta stimulation, but only the Thy 1(+) subset produced MCP-1. Furthermore, only Thy 1(+) fibroblasts up-regulated CD40 surface expression with IL-1beta or interferon-gamma treatment. Engagement of CD40 in the Thy 1(+) subpopulation induced IL-6, IL-8, and MCP-1. The discovery of functional subsets of reproductive tract fibroblasts now permits assessment of their roles in the normal functions of the reproductive tract and in disease states such as adhesions and menorrhagia.

Hormonal contraception can suppress natural antimicrobial gene transcription in human endometrium.

OBJECTIVE To determine the effect of hormonal contraception with a combined oral contraceptive pill and levonorgestrel intrauterine system on the expression of the natural antimicrobials secretory leukocyte protease inhibitor, beta-defensins 1 and 2, and granulysin in human endometrium. DESIGN Observational study. SETTING Day case ward in a department of obstetrics and gynecology. PATIENT(S) Fifty seven women undergoing gynecologic procedures for benign conditions; 24 received no contraception for more than 3 months, 20 received a combined oral contraceptive for more than 3 months, and 13 wore a levonorgestrel intrauterine system for more than 3 months. MAIN OUTCOME MEASURE(S) Endometrial samples were collected from all women. Messenger RNA was extracted and quantitative polymerase chain reaction was used to investigate expression of secretory leukocyte protease inhibitor, beta-defensin 1, beta-defensin 2, and granulysin. Immunohistochemistry for secretory leukocyte protease inhibitor was performed. RESULT(S) All antimicrobials varied cyclically. The level of secretory leukocyte protease inhibitor was maximal in the late secretory and menstrual phase, beta-defensin 1 in the mid secretory phase, granulysin in the late secretory phase, and beta-defensin 2 in the menstrual phase. Use of a combined oral contraceptive or levonorgestrel intrauterine system use decreased messenger RNA expression of beta-defensin 1 and 2 and granulysin but not secretory leukocyte protease inhibitor. CONCLUSION(S) Endogenous and exogenous sex-steroid hormones, in the form of a combined oral contraceptive or levonorgestrel intrauterine system, influence gene transcription of secretory leukocyte protease inhibitor, beta-defensin 1, beta-defensin 2, and granulysin in the endometrium.

Inflammatory mediators and endometrial function—focus on the perivascular cell

Human endometrium has a unique vascular architecture that allows menstruation, the shedding of a well-vascularised tissue layer, with limited bleeding. Blood loss is controlled at least in part by constriction of the perivascular cells, myofibroblasts that surround the spiral arterioles and have contractile activity. These perivascular cells, which are coupled to endothelial cells by processes, are responsive to changes in progesterone levels and express chemokines, cytokines and prostaglandins (PG) crucial to the control of leukocyte entry into endometrium. In this location the chemokine interleukin-8 (IL-8) and prostaglandin E (PGE) will have synergistic effects on leukocyte entry. CD40 is also expressed on the perivascular cells. Activation of CD40 by CD40 ligand is known to increase COX-2 and IL-8 expression in endometrial fibroblasts. The likely source of CD40 ligand in the uterus is platelets. Thus ingress of platelets will up-regulate NFkappaB by activating CD40 and increase agents such as PGE which will stimulate further the ingress of platelets. There is thus the possibility of a spiralling inflammatory response. This response however, is normally modulated by progesterone raising the threshold of the NFkappaB pathway and in the presence of high progesterone levels activation of CD40 will be ineffective. When progesterone falls at the end of the ovarian cycle and the restrictions on activation are lost, the perivascular cells will respond, initiating leukocyte entry, vasoconstriction-vasodilatation cycles with associated hypoxia and consequent sloughing off of the endometrium. The perivascular cell in endometrium is pivotal in both menstruation and early pregnancy and we need to understand this cell better to devise more effective medical treatment for menstrual dysfunction.