Roberta Rizzo

HLA-G expression in early embryos is a fundamental prerequisite for the obtainment of pregnancy.

Different mechanisms mediated by the expression of the HLA‐class Ib HLA‐G products are suggested to account for the induction of immune tolerance against the paternal antigens of the fetus during pregnancy. Soluble HLA‐G antigens, mainly produced by cytotrophoblast cells at the materno‐fetal interface and circulating in the body fluids, show a capacity analogous to that of membrane‐boundstructures to inhibit NK cells. In the present report we have investigated, using specific ELISA, the presence of sHLA‐G molecules in culture supernatants of early embryos obtained by in vitro fertilization (IVF) before transfer. The data obtained from the analysis of 285 supernatants corresponding to 101 IVF procedures (43 IVF, 58 intracytoplasmic sperm injection) identify two groups of patients on the basis of sHLA‐G antigen presence. No differences in clinical parameters were observed between the groups, but positive embryo implantations occurred only in women showing sHLA‐G molecules in culture supernatants (Fishers exact p value 2.56×10–3). The results obtained indicate that expression of HLA‐G products in embryo cells is a mandatory, but not sufficient, prerequisite for the development of pregnancy.

Presence of detectable levels of soluble HLA-G molecules in CSF of relapsing–remitting multiple sclerosis: relationship with CSF soluble HLA-I and IL-10 concentrations and MRI findings

We have investigated the presence of non-classical soluble HLA-G molecules (sHLA-G) in cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients and the possible relationships between CSF levels of sHLA-G, classical soluble HLA-I (sHLA-I) molecules, IL-10 amounts and Magnetic Resonance Imaging (MRI) findings were evaluated. We studied by ELISA technique the sHLA-I, sHLA-G and IL-10 levels in CSF of 50 relapsing-remitting (RR) MS patients stratified according to clinical and MRI evidence of disease activity. Thirty-six patients with other inflammatory neurological disorders (OIND) and 41 with non-inflammatory neurological disorders (NIND) were used as controls. CSF mean levels were significantly higher in MS and OIND than in NIND for sHLA-I (p<0.001) and in MS than in controls for sHLA-G (p<0.001), with no differences among the various groups for IL-10 mean concentrations. An increase in CSF sHLA-I was found in MS patients with Gd-enhancing lesions (p<0.01), while sHLA-G and IL-10 were more represented in MS patients without lesional activity on MRI scans (p<0.02). In MRI-inactive MS, CSF IL-10 mean concentrations were significantly greater in patients with CSF-detectable levels of sHLA-G than in those without any evidence of CSF sHLA-G expression (p<0.05). Our findings suggest that CSF classical sHLA-I and non-classical sHLA-G levels may modulate MS activity as assessed by MRI acting in opposite directions. The association observed between sHLA-G and IL-10 when Gd-enhancing lesion resolved indicates a potential immunoregulatory role for IL-10 in the control of MS disease activity by shifting the sHLA-I/sHLA-G balance towards sHLA-G response.

Virologic and Immunologic Evidence Supporting an Association between HHV-6 and Hashimoto's Thyroiditis

Hashimotos thyroiditis (HT) is the most common of all thyroid diseases and is characterized by abundant lymphocyte infiltrate and thyroid impairment, caused by various cell- and antibody-mediated immune processes. Viral infections have been suggested as possible environmental triggers, but conclusive data are not available. We analyzed the presence and transcriptional state of human herpesvirus 6 (HHV-6) in thyroid fine needle aspirates (FNA) and peripheral blood mononuclear cells (PBMCs) from 34 HT patients and 28 controls, showing that HHV-6 DNA prevalence (82% vs. 10%, p≤0.001) and viral load were significantly increased in FNA from HT patients, and thyrocytes from HT FNA displayed a 100-fold higher HHV-6 DNA load compared to infiltrating lymphocytes. In addition, while HHV-6 was strictly latent in positive samples from controls, a low grade acute infection was detected in HT samples. HHV-6 variant characterization was carried out in 10 HT FNA samples, determining that all specimens harbored HHV-6 Variant A. The tropism of HHV-6 for thyroid cells was verified by infection of Nthy-ori3-1, a thyroid follicular epithelial cell line, showing that thyrocytes are permissive to HHV-6 replication, which induces de novo expression of HLA class II antigens. Furthermore, HHV-6-infected Nthy-ori3-1 cells become targets for NK-mediated killing, NK cells from HT patients show a significantly more efficient killing of HHV-6 infected thyroid cells than healthy controls, and HT patients have increased T-cell responses to HHV-6 U94 protein, associated to viral latency. These observations suggest a potential role for HHV-6 (possibly variant A) in the development or triggering of HT.

Soluble human leukocyte antigen-G isoforms in maternal plasma in early and late pregnancy.

Problem Human Leukocyte Antigen (HLA)‐G is a class Ib gene located in the human major histocompatibility complex (MHC). Several lines of investigation indicate that the HLA‐G molecule is involved in the maternal acceptance of the semi‐allogenic fetus during pregnancy and in the development of tolerance. Expression of soluble HLA‐G (sHLA‐G) is positively correlated with successful in vitro fertilization (IVF) treatments, and aberrant expression of HLA‐G in certain complications of pregnancy, such as pre‐eclampsia and spontaneous abortion, has been reported. The main purpose of this study was to investigate the levels of different soluble HLA‐G isoforms in maternal plasma in early and late pregnancy.

A decreased positivity for CD90 on human mesenchymal stromal cells (MSCs) is associated with a loss of immunosuppressive activity by MSCs

Biologic and clinical interest in human mesenchymal stromal cells (hMSC) has risen over the last years, mainly due to their immunosuppressive properties. In this study, we investigated the basis of immunomodulant possible variability using hMSC from different sources (amniotic membrane, chorion, and bone marrow from either healthy subjects or patients with hematological malignancies, HM) and having discordant positivity for several immunological markers. The CD90+ hMSC reduced lymphoproliferative response in phytohemagglutinin (PHA) activated peripheral blood mononuclear cells (PBMC) via sHLA‐G and IL‐10 up‐modulation. On the contrary, hMSC showing a significantly lower expression for CD90 antigen, elicited a lymphoproliferative allogeneic response in PHA/PBMCs without any increase in soluble HLA‐G and IL‐10 levels. These data seems to suggest that CD90 molecule may be considered a novel predictive marker for hMSC inhibitory ability, and might cooperate with HLA‐G molecule in regulating suppressive versus stimulatory properties of hMSC. These results may have clinical implication in either transplantation or in regenerative medicine fields.

The importance of HLA-G expression in embryos, trophoblast cells, and embryonic stem cells.

The nonclassical HLA-G molecule is a trophoblast-specific molecule present in almost every pregnancy. It differs from classical HLA class I molecules by the low degree of allelic variants and the high diversity of protein structures. HLA-G is reported to be a tolerogenic molecule that acts on cells of both innate and adaptive immunity. At the maternal–fetal interface HLA-G seems to be responsible largely for the reprogramming of local maternal immune response. This review will focus on the HLA-G gene expression profile in pregnancy, in preimplantation embryos, and in human embryonic stem cells with emphasis on the structural diversity of the HLA-G protein and its potential functional and diagnostic implications.

ORIGINAL ARTICLE: Soluble Human Leukocyte Antigen-G Isoforms in Maternal Plasma in Early and Late Pregnancy

Problem Human Leukocyte Antigen (HLA)‐G is a class Ib gene located in the human major histocompatibility complex (MHC). Several lines of investigation indicate that the HLA‐G molecule is involved in the maternal acceptance of the semi‐allogenic fetus during pregnancy and in the development of tolerance. Expression of soluble HLA‐G (sHLA‐G) is positively correlated with successful in vitro fertilization (IVF) treatments, and aberrant expression of HLA‐G in certain complications of pregnancy, such as pre‐eclampsia and spontaneous abortion, has been reported. The main purpose of this study was to investigate the levels of different soluble HLA‐G isoforms in maternal plasma in early and late pregnancy.

A functional role for soluble HLA-G antigens in immune modulation mediated by mesenchymal stromal cells.

BACKGROUND It has been suggested that soluble factors produced by bone marrow (BM) mesenchymal stromal cells (MSC) play a fundamental role in mediating immune modulation. HLA-G antigens (Ag) are major histocompatibility complex (MHC) class Ib molecules characterized by a limited polymorphism and a splicing mechanism that regulates the production of membrane-bound and soluble isoforms. Interleukin-10 (IL-10) cytokine is one of the main up-modulators of soluble HLA-G Ag (sHLA-G) production by CD14+ peripheral blood monocyte cells and increased IL-10 levels are reported to be associated with MSC immune modulation. METHODS We investigated, by specific enzyme-linked immunosorbent assay (ELISA), the possible role of sHLA-G molecules in the inhibition of the peripheral blood mononuclear cell (PBMC) response to phytohemagglutinin (PHA) mediated by MSC from different sources. RESULTS There was a significant correlation between the presence of increased levels of sHLA-G and IL-10 in the MSC/PBMC/PHA culture supernatants and lymphoproliferative inhibition. Neutralizing experiments performed with monoclonal Ab directed against HLA-G and IL-10 molecules confirmed the inhibitory ability of sHLA-G Ag. Furthermore, exogenous IL-10 induced sHLA-G molecule secretion by MSC alone in a polymorphic way, while a longitudinal analysis confirmed the loss of MSC inhibitory functions in relation to in vitro MSC aging. DISCUSSION Overall the results obtained suggest a functional role for sHLA-G molecules in inhibiting the PBMC response mediated by MSC. Moreover, the ability of IL-10 to induce sHLA-G Ag production by MSC alone could be proposed as a marker of MSC functional ability.

Intrathecal synthesis of soluble HLA-G and HLA-I molecules are reciprocally associated to clinical and MRI activity in patients with multiple sclerosis

The aim of this study was to provide further insight into the effective contribution of classical soluble HLA-A, B and C class Ia (sHLA-I) and non-classical soluble HLA-G class Ib (sHLA-G) molecules in immune dysregulation occurring in multiple sclerosis (MS). We evaluated by enzyme-linked immunosorbent assay (ELISA) technique intrathecal synthesis and cerebrospinal fluid (CSF) and serum levels of sHLA-I and sHLA-G in 69 relapsing-remitting (RR), 21 secondary progressive (SP) and 13 primary progressive (PP) MS patients stratified according to clinical and magnetic resonance imaging (MRI) evidence of disease activity. We also tested, as neurological controls, 91 patients with other inflammatory neurological disorders (OIND) and 92 with non-inflammatory neurological disorders (NIND). Eighty-two healthy volunteers served as further controls for sHLA-I and sHLA-G determinations. An intrathecal production of sHLA-I and sHLA-G detected by specific indexes was significantly more frequent in MS patients than in controls (p<0.01). An intrathecal synthesis of sHLA-I was prevalent in clinically (p<0.02) and MRI active (p<0.001) MS, whereas a CSF-restricted release of sHLA-G predominated in clinically (p<0.01) and MRI stable (p<0.001) MS. sHLA-I levels were low in the serum of clinically active (p<0.001) and high in the CSF of MRI active (p<0.01) MS. Conversely, sHLA-G concentrations were decreased in the serum of clinically stable MS (p<0.01) and increased in the CSF of MRI inactive MS (p<0.001). The trends towards a negative correlation observed between CSF and serum concentrations and intrathecal synthesis of sHLA-I and sHLA-G in patients without evidence of clinical and MRI activity confirmed that intrathecal production and fluctuations in CSF and serum concentrations of sHLA-I and sHLA-G were reciprocal in MS. Our results suggest that, in MS, a balance between classical sHLA-I and non-classical sHLA-G products modulating both MRI and clinical disease activity in opposite directions may exist.

Enhanced P2X7 Activity in Human Fibroblasts From Diabetic Patients A Possible Pathogenetic Mechanism for Vascular Damage in Diabetes

Objective—We have investigated expression and function of the P2X7 receptor in fibroblasts from healthy subjects and patients with type 2 diabetes. Methods and Results—Fibroblasts were isolated from skin biopsies. P2X7 receptor expression in both cell populations was measured by functional assays, RT-PCR, fluorescence-activated cell sorter, and immunoblotting. We found that fibroblasts from diabetic subjects are characterized by enhanced P2X7-mediated responses as indicated by increased shape changes, microvesiculation, enhanced fibronectin and interleukin 6 secretion, and accelerated apoptosis. These responses were blocked by preincubation with the P2X blockers KN-62, oxidized ATP, or pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid). Furthermore, we also found a higher level of spontaneous fibronectin secretion and of apoptosis in fibroblasts from diabetic compared with healthy subjects. Both higher basal level of fibronectin secretion and spontaneous rate of apoptosis were likely attributable to the increased pericellular concentration of ATP because fibroblasts from diabetic subjects released 3× as much ATP into the supernatants compared with fibroblasts from healthy subjects. Conclusions—We conclude that fibroblasts from type 2 diabetes patients are characterized by a hyperactive purinergic loop based either on a higher level of ATP release or on increased P2X7 reactivity.