Patricia D.A. Lima

DBA-Lectin Reactivity Defines Mouse Uterine Natural Killer Cell Subsets with Biased Gene Expression

ABSTRACT Endometrial decidualization, a process essential for blastocyst implantation in species with hemochorial placentation, is accompanied by an enormous but transient influx of natural killer (NK) cells. Mouse uterine NK (uNK) cell subsets have been defined by diameter and cytoplasmic granule number, reflecting stage of maturity, and by histochemical reactivity with Periodic Acid Schiff (PAS) reagent with or without co-reactivity with Dolichos biflorus agglutinin (DBA) lectin. We asked whether DBA− and DBA+ mouse uNK cells were equivalent using quantitative RT-PCR analyses of flow-separated, midpregnancy (Gestation Day [gd] 10) cells and immunohistochemistry. CD3E (CD3)−IL2RB (CD122)+DBA cells were identified as the dominant Ifng transcript source. Skewed IFNG production by uNK cell subsets was confirmed by analysis of uNK cells from eYFP-tagged IFNG-reporter mice. In contrast, CD3E−IL2RB+DBA+ uNK cells expressed genes compatible with significantly greater potential for IL22 synthesis, angiogenesis, and participation in regulation mediated by the renin-angiotensin system (RAS). CD3E−IL2RB+DBA+ cells were further divided into VEGFA+ and VEGFA− subsets. CD3E−IL2RB+DBA+ uNK cells but not CD3E−IL2RB+DBA− uNK cells arose from circulating, bone marrow-derived progenitor cells by gd6. These findings indicate the heterogeneous nature of mouse uNK cells and suggest that studies using only DBA+ uNK cells will give biased data that does not fully represent the uNK cell population.

Ly49 Receptors: Innate and Adaptive Immune Paradigms

The Ly49 receptors are type II C-type lectin-like membrane glycoproteins encoded by a family of highly polymorphic and polygenic genes within the mouse natural killer (NK) gene complex. This gene family is designated Klra, and includes genes that encode both inhibitory and activating Ly49 receptors in mice. Ly49 receptors recognize class I major histocompatibility complex-I (MHC-I) and MHC-I-like proteins on normal as well as altered cells. Their functional homologs in humans are the killer cell immunoglobulin-like receptors, which recognize HLA class I molecules as ligands. Classically, Ly49 receptors are described as being expressed on both the developing and mature NK cells. The inhibitory Ly49 receptors are involved in NK cell education, a process in which NK cells acquire function and tolerance toward cells that express “self-MHC-I.” On the other hand, the activating Ly49 receptors recognize altered cells expressing activating ligands. New evidence shows a broader Ly49 expression pattern on both innate and adaptive immune cells. Ly49 receptors have been described on multiple NK cell subsets, such as uterine NK and memory NK cells, as well as NKT cells, dendritic cells, plasmacytoid dendritic cells, macrophages, neutrophils, and cells of the adaptive immune system, such as activated T cells and regulatory CD8+ T cells. In this review, we discuss the expression pattern and proposed functions of Ly49 receptors on various immune cells and their contribution to immunity.

Leukocyte driven-decidual angiogenesis in early pregnancy

Successful pregnancy and long-term, post-natal maternal and offspring cardiac, vascular and metabolic health require key maternal cardiovascular adaptations over gestation. Within the pregnant decidualizing uterus, coordinated vascular, immunological and stromal cell changes occur. Considerable attention has been given to the roles of uterine natural killer (uNK) cells in initiating decidual spiral arterial remodeling, a process normally completed by mid-gestation in mice and in humans. However, leukocyte roles in much earlier, region specific, decidual vascular remodeling are now being defined. Interest in immune cell-promoted vascular remodeling is driven by vascular aberrations that are reported in human gestational complications such as infertility, recurrent spontaneous abortion, preeclampsia (PE) and fetal growth restriction. Appropriate maternal cardiovascular responses during pregnancy protect mothers and their children from later cardiovascular disease risk elevation. One of the earliest uterine responses to pregnancy in species with hemochorial placentation is stromal cell decidualization, which creates unique niches for angiogenesis and leukocyte recruitment. In early decidua basalis, the aspect of the implantation site that will cradle the developing placenta and provide the major blood vessels to support mature placental functions, leukocytes are greatly enriched and display specialized properties. UNK cells, the most abundant leukocyte subset in early decidua basalis, have angiogenic abilities and are essential for normal early decidual angiogenesis. The regulation of uNK cells and their roles in determining maternal and progeny cardiovascular health over pregnancy and postpartum are discussed.

Ly49 receptors activate angiogenic mouse DBA+ uterine natural killer cells

In humans, specific patterns of killer immunoglobulin-like receptors (KIRs) expressed by uterine natural killer (uNK) cells are linked through HLA-C with pregnancy complications (infertility, recurrent spontaneous abortion, intrauterine growth restriction and preeclampsia). To identify mechanisms underpinning the associations between NK cell activation and pregnancy success, pregnancies were studied in mice with genetic knockdown (KD) of the MHC-activated Ly49 receptor gene family. B6.Ly49KD pregnancies were compared to normal control B6.Ly49129 and C57BL/6 (B6) pregnancies. At mid-pregnancy (gestation day (gd9.5)), overall uNK cell (TCRβ−CD122+DBA+DX5− (DBA+DX5−)) and TCRβ−CD122+DBA−DX5+ (DBA−DX5+)) frequencies in pregnant uterus were similar between genotypes. Ly49KD lowered the normal frequencies of Ly49+ uNK cells from 90.3% to 47.8% in DBA−DX5+ and 78.8% to 6.3% in DBA+DX5− uNK cell subtypes. B6.Ly49KD matings frequently resulted in expanded blastocysts that did not implant (subfertility). B6.Ly49KD mice that established pregnancy had gestational lengths and litter sizes similar to controls. B6.Ly49KD neonates, however, were heavier than controls. B6.Ly49KD implantation sites lagged in early (gd6.5) decidual angiogenesis and were deficient in mid-pregnancy (gd10.5) spiral arterial remodelling. Ultrastructural analyses revealed that B6.Ly49KD uNK cells had impaired granulogenesis, while immunocytochemistry revealed deficient vascular endothelial cell growth factor (VEGFA) production. Perforin and IFNG expression were normal in B6.Ly49KD uNK cells. Thus, in normal mouse pregnancies, Ly49 receptor signaling must promote implantation, early decidual angiogenesis and mid-pregnancy vascular remodelling. Disturbances in these functions may underlie the reported genetic associations between human pregnancy complications and the inability of specific conceptus MHCs to engage activating KIR on uNK cells.

Gestational Modification of Murine Spiral Arteries Does Not Reduce Their Drug-Induced Vasoconstrictive Responses In Vivo

ABSTRACT Dynamic control of maternal blood flow to the placenta is critical for healthy pregnancy. In many tissues, microvasculature arteries control the flow. The uterine/endometrial vascular bed changes during pregnancy include physiological remodeling of spiral arteries from constricted artery-like structures to dilated vein-like structures between Gestation Day 8 (gd8) and gd12 in mice and wk 12–16 in humans. These changes occur, in part, due to local environmental changes such as decidualization, recruitment of maternal uterine natural killer cells, and invasion of conceptus-derived trophoblasts. No current preparations permit in vivo testing of decidual microvascular reactivity. We report an in vivo intravital fluorescence microscopy model that permits functional study of the entire uterine microvascular bed (uterine, arcuate, radial, basal, and spiral arteries) in gravid C57BL/6 mice. Vascular reactivities were measured at gd8 prespiral arterial remodeling and gd12 (postremodeling) to a range of concentrations of adenosine (10−8–10−6 M), acetylcholine (10−7–10−5 M), phenylephrine (10−7–10−5 M), and angiotensin II (10−8–10−6 M). At baseline, each arterial branch order was significantly more dilated on gd12 than gd8. Each microvascular level responded to each agonist on gd8 and gd12. At gd12, vasodilation to adenosine was attenuated in uterine, arcuate, and basal arteries, while constrictor activity to angiotensin II was enhanced in uterine and arcuate arteries. The tendency for increasing vasoconstriction between gd8 to gd12 and the constrictor responses of modified spiral arteries were unexpected findings that may reflect influences of the intact in vivo environment rather than inherent properties of the vessels and may be relevant to ongoing human pregnancies.

Homing Receptor Expression Is Deviated on CD56+ Blood Lymphocytes during Pregnancy in Type 1 Diabetic Women

Type 1 Diabetes Mellitus (T1DM) is characterized by an augmented pro-inflammatory immune state. This contributes to the increased risk for gestational complications observed in T1DM mothers. In normal pregnancies, critical immunological changes occur, including the massive recruitment of lymphocytes, particularly CD56bright NK cells, into early decidua basalis and a 2nd trimester shift towards Type 2 immunity. Decidual CD56bright NK cells arise at least partly from circulating progenitors expressing adhesion molecules SELL and ITGA4 and the chemokine receptors CXCR3 and CXCR4. In vitro studies show that T1DM reduces interactions between blood CD56+ NK cells and decidual endothelial cells by reducing SELL and ITGA4-based interactions. To address the mechanisms by which specific lymphocyte subsets may be recruited from the circulation during pregnancy and whether these mechanisms are altered in T1DM, flow cytometry was used to examine eight peripheral blood lymphocyte subsets (Type 1 (IL18R1+) and Type 2 (IL1RL1+) CD56bright NK, CD56dim NK, NKT and T cells) from control and T1DM women. Blood was collected serially over pregnancy and postpartum, and lymphocytes were compared for expression of homing receptors SELL, ITGA4, CXCR3, and CXCR4. The decline of Type 1/Type 2 immune cells in normal pregnancy was driven by an increase in Type 2 cells that did not occur in T1DM. CD56bright NK cells from control women had the highest expression of all four receptors with greatest expression in 2nd trimester. At this time, these receptors were expressed at very low levels by CD56bright NK cells from TIDM patients. Type 1/Type 2 NKT cell ratios were not influenced by either pregnancy or TIDM. Our results suggest that T1DM alters immunological balances during pregnancy with its greatest impact on CD56bright NK cells. This implicates CD56bright NK cells in diabetic pregnancy complications.

Increased Drp1-Mediated Mitochondrial Fission Promotes Proliferation and Collagen Production by Right Ventricular Fibroblasts in Experimental Pulmonary Arterial Hypertension

Introduction: Right ventricular (RV) fibrosis contributes to RV failure in pulmonary arterial hypertension (PAH). The mechanisms underlying RV fibrosis in PAH and the role of RV fibroblasts (RVfib) are unknown. Activation of the mitochondrial fission mediator dynamin-related protein 1 (Drp1) contributes to dysfunction of RV myocytes in PAH through interaction with its binding partner, fission protein 1 (Fis1). However, the role of mitochondrial fission in RVfib and RV fibrosis in PAH is unknown. Objective: We hypothesize that mitochondrial fission is increased in RVfib of rats with monocrotaline (MCT)-induced PAH. We evaluated the contribution of Drp1 and Drp1–Fis1 interaction to RVfib proliferation and collagen production in culture and to RV fibrosis in vivo. Methods: Vimentin (+) RVfib were enzymatically isolated and cultured from the RVs of male Sprague–Dawley rats that received MCT (60 mg/kg) or saline. Mitochondrial morphology, proliferation, collagen production, and expression of Drp1, Drp1 binding partners and mitochondrial fusion mediators were measured. The Drp1 inhibitor mitochondrial division inhibitor 1 (Mdivi-1), P110, a competitive peptide inhibitor of Drp1–Fis1 interaction, and siRNA targeting Drp1 were assessed. Subsequently, prevention and regression studies tested the antifibrotic effects of P110 (0.5 mg/kg) in vivo. At week 4 post MCT, echocardiography and right heart catheterization were performed. The RV was stained for collagen. Results: Mitochondrial fragmentation, proliferation rates and collagen production were increased in MCT-RVfib versus control-RVfib. MCT-RVfib had increased expression of activated Drp1 protein and a trend to decreased mitofusin-2 expression. Mdivi-1 and P110 inhibited mitochondrial fission, proliferation and collagen III expression in MCT-RVfib. However, P110 was only effective at high doses (1 mM). siDrp1 also reduced fission in MCT-RVfib. Despite promising results in cell therapy, in vivo therapy with P110 failed to prevent or regress RV fibrosis in MCT rats, perhaps due to failure to achieve adequate P110 levels or to the greater importance of interaction of Drp1 with other binding partners. Conclusion: PAH RVfib have increased Drp1-mediated mitochondrial fission. Inhibiting Drp1 prevents mitochondrial fission and reduces RVfib proliferation and collagen production. This is the first description of disordered mitochondrial dynamics in RVfib and suggests that Drp1 is a potential new antifibrotic target.

Unique Features of Endometrial Dynamics During Pregnancy

Chapter Summary After blastocysts cross the uterine epithelium and begin interstitial implantation, the critical process of establishing the chorioallantoic placenta begins. This precedes the stage of rapid fetal growth that depends upon the placenta accessing maternal arterial blood, which provides adequate nourishment and oxygen supplies for fetal growth. The key events in the placental development process occur in the mesometrial endometrium. This tissue region experiences complete remodeling of its components. This chapter discusses the changes in the cellular and tissue biology of uterine epithelium that support receptivity for blastocyst implantation and support development of the utero-placental circulation. This chapter is complementary to Chapter 11 (decidua reaction) and provides a synthesis of content from Chapters 10 and 12 Chapter 10 Chapter 12 (ectoplacental and placental trophoblast), with the integration of new information and emphasis on the differences between mesometrial and antimesometrial decidua. It also gives an introduction to content in Chapters 15, 16 (uterine and utero-placental vasculature), and 19 Chapter 15 Chapter 16 Chapter 19 (uterine leukocytes).

Circulating progenitor and angiogenic cell frequencies are abnormally static over pregnancy in women with preconception diabetes: A pilot study

Type 1 and 2 diabetes decrease the frequencies and functional capacities of circulating angiogenic cells (CAC). Diabetes also elevates gestational complications. These observations may be interrelated. We undertook pilot studies to address the hypothesis that preconception diabetes deviates known gestational increases in CACs. Cross-sectional study of type 1 diabetic, type 2 diabetic and normoglycemic pregnant women was conducted at 1st, 2nd, and 3rd trimester and compared to a 6mo postpartum surrogate baseline. Circulating progenitor cells (CPC; CD34+CD45dimSSlow) and CACs (CD34+CD45dimSSlow expressing CD133 without or with KDR) were quantified by flow cytometry and by colony assay (CFU-Hill). In pregnant normoglycemic women, CD34+CD45dimSSlow cell frequency was greater in 1st and 3rd trimester than postpartum but frequency of these cells was static over type 1 or 2 diabetic pregnancies. Type 1 and type 2 diabetic women showed CACs variance versus normal controls. Type 1 diabetic women had more total CD34+KDR+ CACs in 1st trimester and a higher ratio of CD133+KDR+ to total CD133+ cells in 1st and 2nd trimesters than control women, demonstrating an unbalance in CD133+KDR+ CACs. Type 2 diabetic women had more CD133+KDR+ CACs in 1st trimester and fewer CD133+KDR- CACs at mid-late pregnancy than normal pregnant women. Thus, pregnancy stage-specific physiological fluctuation in CPCs (CD34+) and CACs (CD133+KDR+ and CD133+KDR-) did not occur in type 1 and type 2 diabetic women. Early outgrowth colonies were stable across normal and diabetic pregnancies. Therefore, preconception diabetes blocks the normal dynamic pattern of CAC frequencies across gestation but does not alter colony growth. The differences between diabetic and typical women were seen at specific gestational stages that may be critical for initiation of the uterine vascular pathologies characterizing diabetic gestations.