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Biomedical subjects

Giovanni Melioli

Publications and source records attributed to Giovanni Melioli.

15 recordsLinked to original sources
PubMed2005

Distinctive lack of CD48 expression in subsets of human dendritic cells tunes NK cell activation.

CD48 is a glycosyl phosphatidylinositol anchor protein known to be virtually expressed by all human leukocytes. Its ligand, 2B4, is a signaling lymphocyte activation molecule-related receptor involved in NK cell activation. Because dendritic cells (DCs) are strong inducers of NK cell functions, we analyzed the expression of CD48 in different human DC subsets. We observed that monocytes differentiating in DCs promptly down-regulate CD48. Similarly, DCs isolated from inflamed lymph nodes generally do not express CD48. Plasmocytoid DCs do not express CD48 either, whereas myeloid DCs harbored in blood, bone marrow, and thymus express it. In addition, we showed that CD48 expression in DCs affects NK cell functions during NK/DC cross-talk, because NK cells obtained from normal donors and from X-linked lymphoproliferative disease patients are, respectively, triggered or inhibited by DCs expressing surface CD48. Remarkably, IFN-gamma production by lymph node NK cells, in contrast to blood NK cells, can be negatively modulated by 2B4/CD48 interactions, indicating a 2B4 inhibitory pathway in lymph node NK cells. Therefore, the CD48 deficiency of DCs harbored in inflamed lymph nodes that we report in this study might be relevant to successfully activate lymph node NK cells in the early phase of the immune response. Our results show that distinct subsets of human DCs, differently from all other mononuclear hemopoietic cells, specifically do not express CD48. Moreover, the expression of CD48 depends on the anatomic location of DCs and might be related to the tissue-specific 2B4 function (activating or inhibitory) of the NK cells with which they interact.

Antigens, CD↗
PubMed2005

Treatment of EBV-related post-renal transplant lymphoproliferative disease with a tailored regimen including EBV-specific T cells.

The treatment of EBV-associated post-transplant lymphoproliferative disease (PTLD) poses a considerable challenge. Efforts have been made to define regimens based on combination of the available therapeutic agents, chosen and tailored on a patient-by-patient basis, with the aim of augmenting event-free patient and graft survival. Recently, autologous EBV-specific cytotoxic T-lymphocytes (CTL) have proved effective in enhancing EBV-specific immune responses and reducing viral load in organ transplant recipients with active infection. We investigated the use of a tailored combined approach including autologous EBV-specific CTL for the treatment of EBV-related PTLD developing after pediatric kidney transplantation. Five patients with disseminated monoclonal (n = 3) or localized polyclonal (n = 2) PTLD unresponsive to reduction of immunosuppression were enrolled. The patients with disseminated PTLD received 4-5 courses of reduced-dosage polychemotherapy, accompanied by rituximab on the first day of each course, while localized disease was removed surgically. At treatment completion, autologous EBV-specific CTL were infused. All patients showed a complete response to treatment, without therapy-related toxicity or rejection, and persist in remission with good renal function at a median follow-up of 31 months. These preliminary results suggest that a combined chemoimmunotherapy regimen including virus-specific T-cells is well tolerated and potentially effective as first-line treatment of EBV-related PTLD.

Adolescent↗
PubMed2005

The secretion of ibuprofen metabolites interferes with the capillary chromatography of urinary homovanillic acid and 4-hydroxy-3-methoxymandelic acid in neuroblastoma diagnosis.

Neuroblastoma is the most common extracranial solid tumor in children. Abnormal secretion of catecholamines in tissues and body fluids allows for the differential diagnosis of neuroblastoma from other neoplasms and its distinction from non-neoplastic inflammatory diseases. This is achieved by assaying homovanillic acid and 4-hydroxy-3-methoxymandelic acid, the catabolites of catecholamine metabolism. In the course of an evaluation of children with suspected neuroblastoma, homovanillic acid and 4-hydroxy-3-methoxymandelic acid were analyzed in urine samples by capillary gas chromatography with flame ionization detection after extraction and derivatization of these compounds as trimethylsilyl derivatives. In three urine samples a significant increase in biogenic amines was observed, but these results were not confirmed by thin-layer chromatography. Patient history revealed that these children had been treated with ibuprofen, an analgesic and anti-inflammatory drug. To verify how ibuprofen or its metabolites may have interfered with capillary gas chromatography with flame ionization detection, we analyzed the same samples by capillary gas chromatography-mass spectrometry. In urine samples from patients on the drug, the presence of a peak identified as the trimethylsilyl ester of hydroxyibuprofen, which had the same retention time as 4-hydroxy-3-methoxymandelic acid, was found to interfere with the capillary gas chromatography with flame ionization detection analysis of the metabolite. This interference must be taken into account during the laboratory diagnosis of neuroblastoma.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Separation of human serum proteins using the Beckman-Coulter PF2D system: analysis of ion exchange-based first dimension chromatography.

The ProteomeLab PF2D protein fractionation system is a rapid, semi-automated, 2 D-HPLC instrument that uses two different methods to separate plasma serum proteins: ion-exchange chromatography using a wide pH range in the first dimension, and non-porous reverse-phase chromatography in the second dimension. Because this methodology has only very recently been introduced in proteomic laboratories, little is known about the characteristics of PF2D fractionation of human serum proteins. To evaluate the system's application in a clinical laboratory setting, the characteristics of the ion-exchange chromatography-based separation were analyzed. Following fractionation of human serum proteins on a linear pH gradient (ranging from 8.0 to 4.0), each fraction was collected in a cool module of the instrument. Different fractions obtained from the first dimension were then pooled together and loaded on classic 2D gel electrophoresis instrumentation. The different spots obtained were then checked against the Swiss-Prot Data-base. A total of 36 human serum proteins were identified in different PF2D-generated fractions. Some important features of the separation system were observed. Different eluted fractions contained different proteins, thus demonstrating the reliability of the fractionation system. The proteins were also fractionated according to the theoretical isoelectric point (pI). This was consistent with the evidence that the vast majority of immunoglobulins, characterized by an alkaline pI, were not retained by the column and were eluted in the unbound fraction. This outcome also underlines a practical advantage: fractions eluted from pH 8 to pH 4 contained virtually immunoglobulin-depleted serum proteins. This finding supports an immediate use of the PF2D system in a clinical setting, where abundant proteins should be clearly identified to enable evaluation of other less abundant, but potentially relevant, species.

Automation↗
PubMed2005

Eosinophil granulocytes account for indoleamine 2,3-dioxygenase-mediated immune escape in human non-small cell lung cancer.

Indoleamine 2,3-dioxygenase (IDO), a catabolizing enzyme of tryptophan, is supposed to play a role in tumor immune escape. Its expression in solid tumors has not yet been well elucidated: IDO can be expressed by the tumor cells themselves, or by ill-defined infiltrating cells, possibly depending on tumor type. We have investigated IDO expression in 25 cases of non-small cell lung cancer (NSCLC). Using histochemistry and immunohistochemistry, we found that IDO was expressed not by tumor cells, but by normal cells infiltrating the peritumoral stroma. These cells were neither macrophages nor dendritic cells, and were identified as eosinophil granulocytes. The amount of IDO-positive eosinophils varied in different cases, ranging from a few cells to more than 50 per field at x200 magnification. IDO protein in NSCLC was enzymatically active. Therefore, at least in NSCLC cases displaying a large amount of these cells in the inflammatory infiltrate, IDO-positive eosinophils could exert an effective immunosuppressive action. On analyzing the 17 patients with adequate follow-up, a significant relationship was found between the amount of IDO-positive infiltrate and overall survival. This finding suggests that the degree of IDO-positive infiltrate could be a prognostic marker in NSCLC.

Adult↗
PubMed2004

CD40 on adult human airway epithelial cells: expression and proinflammatory effects.

CD40/CD40 ligand interaction is an important pathway for B and T cell cooperation and function; functional CD40 molecules have recently been found on nonhematopoietic cells. We detected CD40 in vivo on normal human respiratory epithelial cells and showed that its expression is increased on inflamed airway epithelium. Subsequently, we analyzed its expression and function on primary cultures of human airway epithelial cells. Our data show that CD40 is up-regulated by IFN-beta and IFN-gamma, its ligation increases the surface expression of CD54 and CD106 and it may stimulate the release of IL-6 and IL-8. The use of Janus kinase 3 (JAK3) and NF-kappaB inhibitors suggests that both basal and CD40-induced release of the two cytokines is JAK3-dependent. Using colocalization techniques, we revealed the existence of CD40/JAK3 and CD40/TNFR-associated factor 2 interplay. The extent of these interactions may be partial (2-40% of the cells) or massive (80-90% of the cells) in cultured cells. Stimulation via CD40 causes a significant increase in the number of cells expressing colocalization only in the cultures displaying low frequency of initial colocalization. Thus, airway epithelial cells, activated by CD40, may behave as effector cells of the inflammation process and should be considered priority targets for anti-inflammatory therapy. This work identifies CD40 and the correlated JAK3 signaling molecule as potential molecular targets to block the inflammatory functions of epithelial cells.

Adult↗
PubMed2003

Human natural killer cell function and their interactions with dendritic cells.

Natural killer (NK) cells have long been considered as "primitive" and "non-specific" effector cells. However, the past 10 years have witnessed dramatic progress in our understanding of how NK cells function and their role in innate defenses. Thanks to specialized inhibitory receptors specific for MHC-class I molecules, they can sense the decrease or loss of these molecules, a typical condition of potentially dangerous cells such as tumor or virally-infected cells. NK cell triggering and lysis of these cells is mediated by several activating receptors and co-receptors that have recently been identified and cloned. While normal cells are usually resistant to the NK-mediated attack, a remarkable exception is represented by dendritic cells (DC). In their immature form (iDC), they are susceptible to NK-mediated lysis because of the expression of low levels of surface MHC-class I molecules. Since the process of DC maturation (mDC) is characterized by the surface expression of high levels of MHC-class I molecules, mDC become resistant to NK cells. Exposure to live bacteria induces rapid DC maturation and, thus, resistance to NK cells. The cross-talk between DC and NK cells is more complex and involves also a DC-dependent NK cell activation and proliferation. Thus, two important players of the innate immunity may be involved in a coordinated regulation of critical events occurring at the interface between innate and adaptive immunity.

Bacterial Infections↗
PubMed2003

Naturally occurring immune response against bacteria commonly involved in upper respiratory tract infections: analysis of the antigen-specific salivary IgA levels.

Lyophilized bacterial lysates, which actively stimulate the immune response, are widely used as vaccines or 'biological response modifiers' in subjects with recurrent bacterial respiratory infections. Since vaccines are indicated in the absence or in the presence of a weak constitutive immune response activity, a better knowledge on the 'naturally' occurring antibacterial immune response at the oropharingeal level should be helpful. A study was, therefore, designed to quantify the presence of salivary IgA directed against surface antigens bacteria frequently involved in the pathogenesis of upper respiratory tract infections: Klebsiella pneumoniae (KP), Staphylococcus aureus (SA), Streptococcus pyogenes (SPy), Morraxella catarrhalis (MC), Haemophylus influenzae (HI), and Streptococcus pnumoniae (SPn). In 34 volunteers (21 adults and 13 children), salivary fluid was collected and the presence of microorganism-specific IgA antibodies evaluated by a novel enzyme immuno-assay. In the whole population only 29 and 24% of subjects had IgA directed, respectively, to KP and SA, while the immune-response against other microbes was detectable in a small population ranging from 12 to 15% of all subjects studied. We found higher proportions of individuals with strain specific salivary IgA in the adult than in the pediatric population for all the microorganism evaluated. In addition, in children, the only strain inducing a significant production of specific IgA at oropharingeal level was KP. Interestingly, only ten out of 21 adults and two out 13 children have at least one significantly high antibody titer against one of the bacteria evaluated. Nevertheless, when a group of healthy donors was treated with a polyvalent mechanical bacterial lysate (Ismigen t.), the large majority developed a specific immune-response in the salivary fluid. These results are thus consistent with the good features of the novel enzyme-immunoassay and with a poor frequency of naturally induced specific anti-microbe antibodies in children and in adults despite the presence on recurrent respiratory infections in their clinical history.

Adult↗
PubMed2003

Expansion of natural killer cells in patients with head and neck cancer: detection of "noninhibitory" (activating) killer Ig-like receptors on circulating natural killer cells.

BACKGROUND: In a group of patients with head and neck cancers (H&NC), the expansion of the population of CD3-,CD16+ natural killer (NK) cells in the peripheral blood was studied. METHODS: Cytofluorimetric analysis of the expression of killer Ig-like receptors (KIR, namely p58.1, p58.2, p58.3, p70, and p140) and CD94-NKG2a was performed. Cytolytic activities were studied using 51Cr release assay. T and NK cell cloning was performed using limiting dilution culture conditions. Cytokine production was analyzed using commercial enzyme immunoassays. RESULTS: Phenotypic analysis showed that the expanded populations were heterogeneous. Even in the presence of a large number of circulating NK cells, "nonspecific" cytolytic capacities were heavily reduced, whereas cytolytic capacity related to T cells was virtually normal. Unlike NK cell clones derived from healthy donors, most NK cells derived from H&NC patients expressed surface "activating" NK cell receptors (KAR) for HLA, detected by use of a redirected cytolytic assay. Analysis of the CD4+ subpopulation at the clonal level demonstrated that they had a severe proliferative defect. CONCLUSION: These experimental data indicated that H&NC patients have a polyclonal expansion of functionally deficient NK cells expressing KAR. In addition, the proliferative capacity of patients' "helper" cells was strongly inhibited, thus accounting for a severe impairment of cytolytic activity of the expanded NK cells.

Cohort Studies↗
PubMed2003

The interaction between NK cells and dendritic cells in bacterial infections results in rapid induction of NK cell activation and in the lysis of uninfected dendritic cells.

NK and DC reciprocal interactions have only recently been investigated. In this study, we focused on the interplay between NK cells and DC in two models of bacterial infection. Immature monocyte-derived DC were cultured in the presence of live Escherichia coli or bacillus Calmette-Guérin. Upon exposure to either extracellular or intracellular bacteria, DC underwent maturation as assessed by the increased levels of expression of CD80,CD86, and HLA molecules and the de novo expression of CD83 and CCR7. Significant amounts of TNF-alpha and IL-12 were released by DC upon infection, whereas IL-2 and IL-15 were barely detectable in culture supernatants. Both infected and uninfected DC were capable of inducing in fresh autologous NK cells the expression of CD69 and HLA-DR and of inducing cell proliferation. Remarkably, however, infected DC were much stronger inducers of NK cell activation and proliferation than uninfected DC. Thus, after just 24 h of NK/DC coculture, only those NK cells that had been exposed to bacteria-infected DC had acquired the ability to lyse autologous immature DC. In addition, infected DC were more resistant to NK-mediated lysis as a consequence of the up-regulation of HLA class I molecule expression on their surface. This study suggests a regulatory circuit involving NK cells and DC in which DC-induced NK cell activation is effectively enhanced by the presence of pathogens. Activated NK cells, by limiting the supply of immature DC, may then exert a control on subsequent innate and adaptive immune responses.

Antigens, CD↗
PubMed2003

IFN-alpha mediates the up-regulation of HLA class I on melanoma cells without switching proteasome to immunoproteasome.

Treatment of melanoma cell lines with IFN-gamma induces the switch from proteasome (PS) to immunoproteasome (iPS). This finding has profound implications for the immunobiology of melanoma cells since certain peptides (such as Melan-A(mart1)(27-35)) are cleaved differently by iPS, thus implying a different ability to be presented by HLA class I molecules. IFN-alpha is a cytokine not only produced during infectious diseases, but also used in the treatment of certain cancers. Nevertheless, the effects of IFN-alpha on the switch of PS to iPS are largely unknown. A comparison of the effect of both IFN-alpha and IFN-gamma was thus carried out on melanoma cell lines. RT-PCR showed that mRNA for iPS subunits (i.e. LMP-2, LMP-7 and MECL-1) was detectable both in untreated and IFN-treated melanoma cells. Immunoblotting analysis revealed that while IFN-gamma was able to consistently induce the switch from PS to iPS, IFN-alpha treatment did not, possibly due to post-transcriptional event(s) blocking the expression of iPS-specific subunits. Finally, Melan-A(mart1)(27-35) peptide was found only in the HPLC-MS spectra from both untreated and IFN-alpha-treated cells, but not upon IFN-gamma treatment. Altogether, these data demonstrate that IFN-alpha does not induce the switch from PS to iPS.

Antibodies↗
PubMed2002

The anti-tumor activity of bacillus Calmette-Guerin in bladder cancer is associated with an increase in the circulating level of interleukin-2.

Bacillus Calmette-Guerin (BCG) is currently employed in the treatment of superficial bladder cancer but, despite its recognized effectiveness in preventing recurrences and progression, the immune mechanisms behind its antitumor activity remain to be delineated. In this study we provide evidence that a prolonged increase in the plasma levels of IL-2, but not IL-1beta, IL-4, IL-10, IL-2R or TNF-alpha occured in patients affected by bladder cancer following effective BCG treatment. Conversely, a drop in circulating IL-2 was consistently associated with tumor relapse. The level of IL-2 was elevated even further 15 days after the last BCG administration in patients who did not experience tumor recurrence, suggesting a prolonged T cell-mediated response against antigens other than BCG. Our results indicate that a specific type 1 immune response plays a major role in the anti-cancer activity of BCG. In addition, monitoring IL-2 plasma levels may offer a useful tool for predicting tumor recurrences.

Adjuvants, Immunologic↗
PubMed2002

Human dendritic cells activate resting natural killer (NK) cells and are recognized via the NKp30 receptor by activated NK cells.

During the innate response to many inflammatory and infectious stimuli, dendritic cells (DCs) undergo a differentiation process termed maturation. Mature DCs activate antigen-specific naive T cells. Here we show that both immature and mature DCs activate resting human natural killer (NK) cells. Within 1 wk the NK cells increase two-- to fourfold in numbers, start secreting interferon (IFN)-gamma, and acquire cytolytic activity against the classical NK target LCL721.221. The DC-activated NK cells then kill immature DCs efficiently, even though the latter express substantial levels of major histocompatibility complex (MHC) class I. Similar results are seen with interleukin (IL)-2--activated NK cell lines and clones, i.e., these NK cells kill and secrete IFN-gamma in response to immature DCs. Mature DCs are protected from activated NK lysis, but lysis takes place if the NK inhibitory signal is blocked by a human histocompatibility leukocyte antigen (HLA)-A,B,C--specific antibody. The NK activating signal mainly involves the NKp30 natural cytotoxicity receptor, and not the NKp46 or NKp44 receptor. However, both immature and mature DCs seem to use a NKp30 independent mechanism to act as potent stimulators for resting NK cells. We suggest that DCs are able to control directly the expansion of NK cells and that the lysis of immature DCs can regulate the afferent limb of innate and adaptive immunity.

Cell Differentiation↗
PubMed2002

T lymphocytes express B7 family molecules following interaction with dendritic cells and acquire bystander costimulatory properties.

Dendritic cells (DC) play a pivotal role in the initiation, maintenance and regulation of the immune response. Here we obtained the first evidence that DC, in the absence of any foreign antigens, induce the expression of B7 family costimulatory molecules, such as CD80, CD86, B7-H1, PD-L2, B7-H3, and B7RP-1, on autologous T lymphocytes. Cell-to-cell contact between DC and T cells was needed in order to obtain this expression on T cells. De novo expressed B7 molecules on T cells were functional since B7+ T cells were able to costimulate the proliferation of highly purified T cells. While both autologous and allogeneic DC were able to induce similar levels of costimulatory molecule expression, the chemokine receptor repertoire on B7+ T cells after interaction with DC varied depending on the presence of allo-antigens during the interaction (CCR7-, CCR5+) or the absence of antigens (CCR7+, CCR5-). In accordance with this different pattern of chemokine receptors in the two conditions, we propose that, after the encounter with DC in lymphoid organs, this peculiar T cell population should reside in the T cell areas of the lymph nodes or migrate to peripheral sites of inflammation, providing a second signal for activating or switching off, respectively, naive or peripheral effector T cells.

Antigen Presentation↗