Claudia Carlino

Uterine NK cell development, migration and function

Uterine natural killer (uNK) cells represent the predominant lymphocytes in the uterus during early pregnancy and in the secretory phase of the menstrual cycle. They are CD56(high)CD16(-) and have low cytotoxicity, but constitutively secrete a number of cytokines, chemokines and angiogenic molecules. uNK cells differ from CD56(high) blood NK cells in several ways, including the killer cell immunoglobulin-like receptor repertoire and expression of some genes induced by hormone environment. uNK cells may arise by in-utero proliferation and differentiation of NK cell progenitors under the control of the sex steroid hormones and/or cytokines, such as interleukin-15, and/or be recruited from CD56(+) blood NK cells that would undergo tissue-specific differentiation in the uterine microenvironment. There is evidence showing that uNK cells display a different pattern of chemokine receptors and adhesion molecules, thus leading to a different migratory response. It has not yet been fully defined which uNK cell function(s) are critical for successful pregnancy. The close encirclement of spiral arteries by NK cells, together with their ability to produce angiogenic factors, suggests that they might influence mucosal vascularization. Their proximity to the extravillous trophoblast supports the idea that uNK cells could recognize these cells as fetal, and regulate their invasion during placentation.

Mechanisms underlying recruitment and accumulation of decidual NK cells in uterus during pregnancy

Natural killer (NK) cells represent the most prominent immune cell type found in the uterus in the first trimester of human pregnancy and in the secretory phase of menstrual cycle. The role of NK cells in pregnancy has been largely discussed over the past years and it is now becoming increasingly clear that they may influence pregnancy outcome at several levels. In normal pregnancy, it appears that the major function of NK cells is to provide benefit by secreting a number of cytokines, chemokines and angiogenic factors rather than to exert a cytotoxic activity. However, the origin of decidual NK cells is still debated and it remains unclear whether they can derive from NK cell populations recruited from peripheral blood and/or other tissues or from self renewal of NK cell progenitors present in the uterus prior to pregnancy or recruited from other tissues. Here, we review the molecular mechanisms underlying peripheral blood NK cell recruitment and its role in the accumulation of NK cells in the decidua during early pregnancy.

Impaired NK-cell migration in WAS/XLT patients: role of Cdc42/WASp pathway in the control of chemokine-induced β2 integrin high-affinity state

We analyzed the involvement of Wiskott-Aldrich syndrome protein (WASp), a critical regulator of actin cytoskeleton remodeling, in the control of natural killer (NK)-cell migration. NK cells derived from patients with Wiskott-Aldrich syndrome/X-linked thrombocytopenia (WAS/XLT), carrying different mutations in the WASP coding gene, displayed reduced migration through intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), or endothelial cells in response to CXCL12/stromal cell-derived factor-1 and CX3CL1/fractalkine. Inhibition of WAS/XLT NK-cell migration was associated with reduced ability of these cells to up-regulate the expression of CD18 activation neoepitope and to adhere to ICAM-1 or VCAM-1 following chemokine stimulation. Moreover, chemokine receptor or beta1 or beta2 integrin engagement on NK cells rapidly resulted in Cdc42 activation and WASp tyrosine phosphorylation as well as in WASp association with Fyn and Pyk-2 tyrosine kinases. NK-cell pretreatment with wiskostatin, to prevent Cdc42/WASp association, impaired chemokine-induced NK-cell migration through ICAM-1 and beta2 integrin activation-dependent neoepitope expression. These results show that the Cdc42/WASp pathway plays a crucial role in the regulation of NK-cell migration by acting as a critical component of the chemokine-induced inside-out signaling that regulates lymphocyte function-associated antigen-1 function and suggest that after integrin or chemokine receptor engagement WASp function is regulated by the coordinate action of both Cdc42 and tyrosine kinases.

REVIEW ARTICLE: Mechanisms Underlying Recruitment and Accumulation of Decidual NK Cells in Uterus During Pregnancy

Natural killer (NK) cells represent the most prominent immune cell type found in the uterus in the first trimester of human pregnancy and in the secretory phase of menstrual cycle. The role of NK cells in pregnancy has been largely discussed over the past years and it is now becoming increasingly clear that they may influence pregnancy outcome at several levels. In normal pregnancy, it appears that the major function of NK cells is to provide benefit by secreting a number of cytokines, chemokines and angiogenic factors rather than to exert a cytotoxic activity. However, the origin of decidual NK cells is still debated and it remains unclear whether they can derive from NK cell populations recruited from peripheral blood and/or other tissues or from self renewal of NK cell progenitors present in the uterus prior to pregnancy or recruited from other tissues. Here, we review the molecular mechanisms underlying peripheral blood NK cell recruitment and its role in the accumulation of NK cells in the decidua during early pregnancy.

Chemerin Regulates NK Cell Accumulation and Endothelial Cell Morphogenesis in the Decidua during Early Pregnancy

CONTEXT Although decidual natural killer (NK) cell accumulation and vascular remodeling are critical steps to ensure successful pregnancy, the molecular mechanisms controlling these events are poorly defined. OBJECTIVE Herein we analyzed whether chemerin, a recently identified chemoattractant involved in many pathophysiological processes, could be expressed in the uterine compartment and could regulate events relevant for the good outcome of pregnancy. DESIGN Chemerin expression in human primary culture of stromal (ST) cells, extravillous trophoblast cells, and decidual endothelial cells (DEC) was analyzed by RT-PCR, ELISA, and Western blot. Migration through ST or DEC of peripheral blood and decidual (d) NK cells from pregnant women was performed using a transwell assay. A DEC capillary-like tube formation assay was used to evaluate endothelial morphogenesis. RESULTS Chemerin is differentially expressed by decidual cells during early pregnancy being present at high levels in ST and extravillous trophoblast cells but not in DEC. Notably, ST cells from pregnant women exhibit and release higher levels of chemerin as compared with ST cells from menopausal or fertile nonpregnant women. Chemerin can support peripheral blood NK cell migration through both DEC and ST cells. Although dNK cells exhibit lower chemerin receptor (CMKLR1) expression than their blood counterpart, CMKLR1 engagement on dNK cells resulted in both ERK activation and migration through decidual ST cells. Interestingly, DEC also express CMKLR1 and undergo ERK activation and capillary-like tube structure formation upon exposure to chemerin. CONCLUSIONS Our data indicate that chemerin is up-regulated during decidualization and might contribute to NK cell accumulation and vascular remodeling during early pregnancy.

HaCaT Cells as a Reliable In Vitro Differentiation Model to Dissect the Inflammatory/Repair Response of Human Keratinocytes

Cultured primary human keratinocytes are frequently employed for studies of immunological and inflammatory responses; however, interpretation of experimental data may be complicated by donor to donor variability, the relatively short culture lifetime, and variations between passages. To standardize the in vitro studies on keratinocytes, we investigated the use of HaCaT cells, a long-lived, spontaneously immortalized human keratinocyte line which is able to differentiate in vitro, as a suitable model to follow the release of inflammatory and repair mediators in response to TNFα or IL-1β. Different treatment conditions (presence or absence of serum) and differentiation stimuli (increase in cell density as a function of time in culture and elevation of extracellular calcium) were considered. ELISA and Multiplex measurement technologies were used to monitor the production of cytokines and chemokines. Taken together, the results highlight that Ca2+ concentration in the medium, cell density, and presence of serum influences at different levels the release of proinflammatory mediators by HaCaT cells. Moreover, HaCaT cells maintained in low Ca2+ medium and 80% confluent are similar to normal keratinocytes in terms of cytokine production suggesting that HaCaT cells may be a useful model to investigate anti-inflammatory interventions/therapies on skin diseases.

REVIEW ARTICLE: Mechanisms Underlying Recruitment and Accumulation of Decidual NK Cells in Uterus During Pregnancy: NK CELL RECRUITMENT IN THE DECIDUA

Natural killer (NK) cells represent the most prominent immune cell type found in the uterus in the first trimester of human pregnancy and in the secretory phase of menstrual cycle. The role of NK cells in pregnancy has been largely discussed over the past years and it is now becoming increasingly clear that they may influence pregnancy outcome at several levels. In normal pregnancy, it appears that the major function of NK cells is to provide benefit by secreting a number of cytokines, chemokines and angiogenic factors rather than to exert a cytotoxic activity. However, the origin of decidual NK cells is still debated and it remains unclear whether they can derive from NK cell populations recruited from peripheral blood and/or other tissues or from self renewal of NK cell progenitors present in the uterus prior to pregnancy or recruited from other tissues. Here, we review the molecular mechanisms underlying peripheral blood NK cell recruitment and its role in the accumulation of NK cells in the decidua during early pregnancy.