Differential microRNA expression between decidual and peripheral blood natural killer cells in early pregnancy.

STUDY QUESTION: Have decidual natural killer (dNK) cells a different microRNA (miRNA or miR) expression pattern compared to NK cells circulating in the peripheral blood (pb) of healthy pregnant women in the first trimester of gestation? SUMMARY ANSWER: dNK cells have a unique miRNA profile, showing exclusive expression of a set of miRNAs and significant up- or down-regulation of most of the miRNAs shared with pbNK cells. WHAT IS KNOWN ALREADY: dNK cells differ from pbNK cells both phenotypically and functionally, and their origin is still debated. Many studies have indicated that miRNAs regulate several important aspects of NK cell biology, such as development, activation and effector functions. STUDY DESIGN, SIZE, DURATION: Decidua basalis and peripheral blood specimens were collected from women (n = 7) undergoing voluntary termination of gestation in the first trimester of pregnancy. dNK and pbNK cells were then highly purified by cell sorting. PARTICIPANTS/MATERIALS, SETTING, METHODS: miRNAs expression was analysed by quantitative RT-PCR (qRT-PCR)-based arrays using RNA purified from freshly isolated and highly purified pbNK and dNK cells. Results from arrays were validated by qRT-PCR assays. The bioinformatics tool ingenuity pathway analysis (IPA) was applied to determine the cellular network targeted by validated miRNAs and the correlated biological functions. MAIN RESULTS AND THE ROLE OF CHANCE: Herein, we identified the most differentially expressed miRNAs in NK cells isolated from peripheral blood and uterine decidua of pregnant women. We found that 36 miRNAs were expressed only in dNK cells and two miRNAs only in pbNK cells. Moreover, 48 miRNAs were commonly expressed by both NK cell preparations although at different levels: 28 were upregulated in dNK cells, while 15 were downregulated compared to pbNK cells. Validation of a selected set (n = 11) of these miRNAs confirmed the differential expression of nine miRNAs: miR-10b and miR-214 expressed only in dNK cells and miR-200a-3p expressed only in pbNK cells; miR-130b-3p, miR-125a-5p, miR-212-3p and miR-454 were upregulated while miR-210-3p and miR-132 were downregulated in dNK cells compared to pbNK cells. IPA network analysis identified a single network connecting all the miRNAs as well as their significant involvement in several classes of functions: 'Organismal injury, Reproductive system disease, Inflammatory disease' and 'Cellular development'. These miRNAs target molecules such as argonaute 2, tumour protein p53, insulin and other genes that belong to the same network and significantly influence cell differentiation and pregnancy. LIMITATIONS, REASONS FOR CAUTION: In the present study, the cellular network and biological functions modulated by miRNAs differentially expressed in dNK and pbNK cells were identified by IPA considering only molecules and relationships that were with confidence 'experimentally observed' in leucocytes. The decidual and pbNK cells that were analysed here are a heterogeneous population and further study will help to disentangle whether there are differences in miRNA production by the different subsets of NK cells. WIDER IMPLICATIONS OF THE FINDINGS: This is the first study describing a different miRNA expression profile in dNK cells compared to matched pbNK cells during the first trimester of pregnancy. Our findings improved the body of knowledge on dNK cell biology and strongly suggest further investigation into the roles of miRNAs that are differentially expressed in human dNK compared to pbNK cells. Our results suggest that specific miRNAs can modulate dNK cell origin and functions, highlighting a potential role of this miRNA signature in human development and diseases. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by grants from the Istituto Pasteur, Fondazione Cenci Bolognetti, the European NoE EMBIC within FP6 (Contract number LSHN-CT-2004-512040), Istituto Italiano di Tecnologia, and Ministero dell'Istruzione, dell'Università e della Ricerca (Ricerche Universitarie), and from Università Politecnica delle Marche. There are no conflicts of interest to declare.

Alterations of maternal plasma HTRA1 level in preeclampsia complicated by IUGR.

We evaluated the presence of HtrA1 in maternal plasma of normal pregnancies and of pregnancies complicated by preeclampsia (PE) without and with Intrauterine Growth Restriction (IUGR). We demonstrate that HtrA1 maternal plasma levels show significant different concentrations in first, second and third trimester of gestation and that HtrA1 concentration increases in maternal plasma of gestations complicated by PE with IUGR compared with control maternal plasma matched for gestational age. Based on these data high maternal plasma levels of HtrA1 could be considered as a possible marker of an occurring IUGR in preeclamptic women.

Unmasking cryptic epitopes after loss of immunodominant tumor antigen expression through epitope spreading.

The basis of intra-tumoral and systemic T cell reactivity toward cancer remains unclear. In particular the role that peripheral stimuli, whether endogenous or exogenous, play in shaping acquired immune response toward cancer remains poorly understood. In this study we document the surfacing of systemic immune reactivity toward a cryptic epitope from the MAGE-12 gene (MAGE-12:170-178), after temporary regression of a single melanoma metastasis, in response to gp100/PMel17-specific vaccination. This emergence was unlikely related to unusually high expression of MAGE-12 by the tumor, by the influence of analog epitopes to MAGE-12:170-178. Because MAGE-12 was unlikely to be expressed at sites other than the tumor, the demonstration of MAGE-12:170-178 reactivity in post- but not pre-vaccination circulating lymphocytes suggests that the systemically observed immune response was influenced by events induced by the vaccine at tumor site or draining lymph nodal areas. Possibly, as suggested by pre-clinical models, immunologic ignorance is the default response toward cancer in humans unless unusual stimulatory conditions occur in peripheral tissues. Surfacing of MAGE-12 specificity occurred in association with loss of gp100/PMel 17 targeted by the vaccine. This finding suggests that vaccinations might have effects beyond their intrinsic specificity and may trigger broader immune responses through epitope spreading by inducing changes within the tumor microenvironment. This may have important practical implication for the development of immunization strategies. Published 2001 Wiley-Liss, Inc.

Kinetics of TCR use in response to repeated epitope-specific immunization.

Selection of T cell-directed immunization strategies is based extensively on discordant information derived from preclinical models. We characterized the kinetics of T cell selection in response to repeated antigenic challenge. By enumerating with epitope/HLA tetrameric complexes (tHLA) vaccine-elicited T cell precursor frequencies (Tc-pf) in melanoma patients exposed to the modified gp100 epitope gp100:209-217 (g209-2M) we observed in most patients that the Tc-pf increased with number of immunizations. One patient's kinetics were further characterized. Dissociation kinetics of g209-2M/tHLA suggested enrichment of T cell effector populations expressing TCR with progressively higher affinity. Furthermore, vaccine-elicited T cells maintained the ability to express IFN-gamma ex vivo and proliferate in vitro. Thus, repeated exposure to immunogenic peptides benefited immune competence. These results provide a rationale for immunization strategies.

Leptin modulates extracellular matrix molecules and metalloproteinases: possible implications for trophoblast invasion.

Leptin is a circulating hormone which plays an important role in the regulation of energy balance, haemopoiesis and reproduction. Leptin and its receptor (leptin-R) are localized in human placental tissue but their function is not known. In this study we have investigated the expression of leptin and leptin-R in the human placenta with particular attention to extravillous cytotrophoblastic cell islands and cell columns which play a pivotal role in trophoblast invasion and placental growth. We demonstrate that leptin-R immunoreactivity shows a strong expression in the distal extravillous cytotrophoblastic cells of cell columns invading the basal plate, whereas leptin expression is homogeneously expressed in all the cellular components of cell columns. Since the invasive ability of the distally located extravillous cytotrophoblast of cell columns is known to be regulated by a variety of proteases and some extracellular matrix molecules, we tested the influence of leptin on the in-vitro production of matrix metalloproteinase (MMP)-2, MMP-9 and fetal fibronectin (fFN) by cytotrophoblastic cells. We demonstrate that leptin increases, in a dose-dependent manner, the secretion of immunoreactive MMP-2 and fFN and enhances the activity of MMP-9 in cultured cytotrophoblastic cells. Our results suggest that leptin and leptin-R could have a role in the invasive processes of the extravillous cytotrophoblastic cells by modulating the expression of MMPs. In addition, these results provide a foundation for studying pathological conditions characterized by insufficient or excessive trophoblast invasion.

Status of activation of circulating vaccine-elicited CD8+ T cells.

Selective blunting of the status of activation of circulating tumor-specific T cells was invoked to explain their paradoxical coexistence with unhampered tumor growth. By analogy, lack of tumor regression in the face of observable melanoma vaccine-induced T cell responses might be attributed to their status of activation. We enumerated with HLA-A*0201/peptide tetramers (tHLA) vaccine-elicited T cell precursor frequency directly in PBMC of patients with melanoma undergoing vaccination with the HLA-A*0201-associated gp100:209-217(210 M) epitope (g209-2 M). Furthermore, we tested by intracellular (IC)-FACS analysis and quantitative real-time PCR (qRT-PCR) the ability of postvaccination PBMC to produce cytokine in response to challenge with vaccine-related epitopes or vaccine-matched (HLA-A*0201) melanoma cells. Vaccine-induced enhancement of T cell precursor frequency could be detected with tHLA in PBMC from six of eight patients studied at frequencies ranging between 0.3 and 2.3% of the total CD8+ population. Stimulation with vaccine-related epitopes induced IFN-gamma expression detectable by IC-FACS or qRT-PCR, respectively, in five and six of these patients. Furthermore, down-regulation of tHLA staining was noted upon cognate stimulation that could be utilized as an additional marker of T cell responsiveness. Finally, we observed in six patients an enhancement of reactivity against vaccine-matched tumor targets that was partly independent of documented vaccine-specific immune responses. A strong correlation was noted between tHLA staining of postvaccination PBMC and IFN-gamma expression by the same samples upon vaccine-relevant stimulation and assessed either by IC-FACS or qRT-PCR. Thus, blunting of the status of T cell activation on itself cannot easily explain the lack of clinical responses observed with vaccination.