Pietro Luigi Poliani

Publications (33)265.16 Total impact

• Source

  Available from: Gaetano Finocchiaro

  Dataset: Frattini el al 2012

  Véronique Frattini, Federica Pisati, Maria Carmela Speranza, Pietro Luigi Poliani, Gianmaria Frigé, Gabriele Cantini, Dimos Kapetis, Manuela Cominelli, Alessandra Rossi, Gaetano Finocchiaro, Serena Pellegatta
• Article: ζ Chain-associated protein of 70 kDa (ZAP70) deficiency in human subjects is associated with abnormalities of thymic stromal cells: Implications for T-cell tolerance.

  Pietro Luigi Poliani, Elena Fontana, Chaim M Roifman, Luigi D Notarangelo
  The Journal of allergy and clinical immunology 12/2012; · 9.17 Impact Factor
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  Available from: Gaetano Finocchiaro

  Article: FOXP3, a novel glioblastoma oncosuppressor, affects proliferation and migration.

  Véronique Frattini, Federica Pisati, Maria Carmela Speranza, Pietro Luigi Poliani, Gianmaria Frigé, Gabriele Cantini, Dimos Kapetis, Manuela Cominelli, Alessandra Rossi, Gaetano Finocchiaro, Serena Pellegatta
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  ABSTRACT: The transcription factor FOXP3 plays an essential role in regulatory T cell development and function. In addition, it has recently been identified as a tumor suppressor in different cancers. Here, we report that FOXP3 is expressed in normal brain but strongly down-regulated in glioblastoma (GB) and in corresponding GB stem-like cells growing in culture as neurospheres (GB-NS), as evaluated by real time-PCR and confirmed by immunohistochemistry on an independent set of GB. FOXP3 expression was higher in low-grade gliomas than in GB. Interestingly, we also found that neurosphere generation, a feature present in 58% of the GB that we examined, correlated with lower expression of FOXP3 and shorter patient survival. FOXP3 silencing in one GB-NS expressing measurable levels of the gene caused a significant increase in proliferation and migration as well as highly aggressive growth in xenografts. Conversely, FOXP3 over-expression impaired GB-NS migration and proliferation in vitro. We also demonstrated using ChiP that FOXP3 is a transcriptional regulator of p21 and c-MYC supporting the idea that dysregulated expression of these factors is a major mechanism of tumorigenesis driven by the loss of FOXP3 expression in gliomas. These findings support the assertion that FOXP3 exhibits tumor suppressor activity in glioblastomas.
  Oncotarget 09/2012; · 4.78 Impact Factor
• Article: Correction of Murine Rag2 Severe Combined Immunodeficiency by Lentiviral Gene Therapy Using a Codon-optimized RAG2 Therapeutic Transgene.

  Niek P van Til, Helen de Boer, Nomusa Mashamba, Agnieszka Wabik, Marshall Huston, Trudi P Visser, Elena Fontana, Pietro Luigi Poliani, Barbara Cassani, Fang Zhang, Adrian J Thrasher, Anna Villa, Gerard Wagemaker
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  ABSTRACT: Recombination activating gene 2 (RAG2) deficiency results in severe combined immunodeficiency (SCID) with complete lack of T and B lymphocytes. Initial gammaretroviral gene therapy trials for other types of SCID proved effective, but also revealed the necessity of safe vector design. We report the development of lentiviral vectors with the spleen focus forming virus (SF) promoter driving codon-optimized human RAG2 (RAG2co), which improved phenotype amelioration compared to native RAG2 in Rag2(-/-) mice. With the RAG2co therapeutic transgene, T-cell receptor (TCR) and immunoglobulin repertoire, T-cell mitogen responses, plasma immunoglobulin levels and T-cell dependent and independent specific antibody responses were restored. However, the thymus double positive T-cell population remained subnormal, possibly due to the SF virus derived element being sensitive to methylation/silencing in the thymus, which was prevented by replacing the SF promoter by the previously reported silencing resistant element (ubiquitous chromatin opening element (UCOE)), and also improved B-cell reconstitution to eventually near normal levels. Weak cellular promoters were effective in T-cell reconstitution, but deficient in B-cell reconstitution. We conclude that immune functions are corrected in Rag2(-/-) mice by genetic modification of stem cells using the UCOE driven codon-optimized RAG2, providing a valid optional vector for clinical implementation.
  Molecular Therapy 06/2012; 20(10):1968-80. · 6.87 Impact Factor
• Article: Gene signatures associated with mouse postnatal hindbrain neural stem cells and medulloblastoma cancer stem cells identify novel molecular mediators and predict human medulloblastoma molecular classification.

  Daniela Corno, Corno Daniela, Mauro Pala, Manuela Cominelli, Barbara Cipelletti, Ketty Leto, Laura Croci, Valeria Barili, Federico Brandalise, Raffaella Melzi, Alessandra Di Gregorio, Lucia Sergi Sergi, Letterio Salvatore Politi, Lorenzo Piemonti, Alessandro Bulfone, Paola Rossi, Ferdinando Rossi, Gian Giacomo Consalez, Pietro Luigi Poliani, Rossella Galli
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  ABSTRACT: Medulloblastoma arises from mutations occurring in stem/progenitor cells located in restricted hindbrain territories. Here we report that the mouse postnatal ventricular zone lining the IV ventricle also harbors bona fide stem cells that, remarkably, share the same molecular profile with cerebellar white matter-derived neural stem cells (NSC). To identify novel molecular mediators involved in medulloblastomagenesis, we compared these distinct postnatal hindbrain-derived NSC populations, which are potentially tumor initiating, with murine compound Ptch/p53 mutant medulloblastoma cancer stem cells (CSC) that faithfully phenocopy the different variants of human medulloblastoma in vivo. Transcriptome analysis of both hindbrain NSCs and medulloblastoma CSCs resulted in the generation of well-defined gene signatures, each reminiscent of a specific human medulloblastoma molecular subclass. Most interestingly, medulloblastoma CSCs upregulated developmentally related genes, such as Ebfs, that were shown to be highly expressed in human medulloblastomas and play a pivotal role in experimental medullo-blastomagenesis. These data indicate that gene expression analysis of medulloblastoma CSCs holds great promise not only for understanding functional differences between distinct CSC populations but also for identifying meaningful signatures that might stratify medulloblastoma patients beyond histopathologic staging.
  Cancer discovery. 05/2012; 2(6):554-68.
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  Available from: Marco Cambiaghi

  Article: Sustained activation of mTOR pathway in embryonic neural stem cells leads to development of tuberous sclerosis complex-associated lesions.

  Laura Magri, Marco Cambiaghi, Manuela Cominelli, Clara Alfaro-Cervello, Marco Cursi, Mauro Pala, Alessandro Bulfone, Jose Manuel Garcìa-Verdugo, Letizia Leocani, Fabio Minicucci, Pietro Luigi Poliani, Rossella Galli
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  ABSTRACT: Tuberous Sclerosis Complex (TSC) is a multisystem genetic disorder characterized by hamartomatous neurological lesions that exhibit abnormal cell proliferation and differentiation. Hyperactivation of mTOR pathway by mutations in either the Tsc1 or Tsc2 gene underlies TSC pathogenesis, but involvement of specific neural cell populations in the formation of TSC-associated neurological lesions remains unclear. We deleted Tsc1 in Emx1-expressing embryonic telencephalic neural stem cells (NSCs) and found that mutant mice faithfully recapitulated TSC neuropathological lesions, such as cortical lamination defects and subependymal nodules (SENs). These alterations were caused by enhanced generation of SVZ neural progeny, followed by their premature differentiation and impaired maturation during both embryonic and postnatal development. Notably, mTORC1-dependent Akt inhibition and STAT3 activation were involved in the reduced self-renewal and earlier neuronal and astroglial differentiation of mutant NSCs. Thus, finely tuned mTOR activation in embryonic NSCs may be critical to prevent development of TSC-associated brain lesions.
  Cell stem cell 11/2011; 9(5):447-62. · 23.56 Impact Factor
• Article: Caveolins in rhabdomyosarcoma.

  Stefania Rossi, Pietro Luigi Poliani, Cristina Missale, Eugenio Monti, Alessandro Fanzani
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  ABSTRACT: Caveolins are scaffolding proteins that play a pivotal role in numerous processes, including caveolae biogenesis, vesicular transport, cholesterol homeostasis and regulation of signal transduction. There are three different isoforms (Cav-1, -2 and -3) that form homo- and hetero-aggregates at the plasma membrane and modulate the activity of a number of intracellular binding proteins. Cav-1 and Cav-3, in particular, are respectively expressed in the reserve elements (e.g. satellite cells) and in mature myofibres of skeletal muscle and their expression interplay characterizes the switch from muscle precursors to differentiated elements. Recent findings have shown that caveolins are also expressed in rhabdomyosarcoma, a group of heterogeneous childhood soft-tissue sarcomas in which the cancer cells seem to derive from progenitors that resemble myogenic cells. In this review, we will focus on the role of caveolins in rhabdomyosarcomas and on their potential use as markers of the degree of differentiation in these paediatric tumours. Given that the function of Cav-1 as tumour conditional gene in cancer has been well-established, we will also discuss the relationship between Cav-1 and the progression of rhabdomyosarcoma.
  Journal of Cellular and Molecular Medicine 06/2011; 15(12):2553-68. · 4.13 Impact Factor
• Article: Lentiviral-mediated gene therapy leads to improvement of B-cell functionality in a murine model of Wiskott-Aldrich syndrome.

  Marita Bosticardo, Elena Draghici, Francesca Schena, Aisha Vanessa Sauer, Elena Fontana, Maria Carmina Castiello, Marco Catucci, Michela Locci, Luigi Naldini, Alessandro Aiuti, Maria Grazia Roncarolo, Pietro Luigi Poliani, Elisabetta Traggiai, Anna Villa
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  ABSTRACT: Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency characterized by thrombocytopenia, eczema, infections, autoimmunity, and lymphomas. Transplantation of hematopoietic stem cells from HLA-identical donors is curative, but it is not available to all patients. We have developed a gene therapy (GT) approach for WAS by using a lentiviral vector encoding for human WAS promoter/cDNA (w1.6W) and demonstrated its preclinical efficacy and safety. To evaluate B-cell reconstitution and correction of B-cell phenotype in GT-treated mice. We transplanted Was(-/-) mice sublethally irradiated (700 rads) with lineage marker-depleted bone marrow wild-type cells, Was(-/-) cells untransduced or transduced with the w1.6W lentiviral vector and analyzed B-cell reconstitution in bone marrow, spleen, and peritoneum. Here we show that WAS protein(+) B cells were present in central and peripheral B-cell compartments from GT-treated mice and displayed the strongest selective advantage in the splenic marginal zone and peritoneal B1 cell subsets. After GT, splenic architecture was improved and B-cell functions were restored, as demonstrated by the improved antibody response to pneumococcal antigens and the reduction of serum IgG autoantibodies. WAS GT leads to improvement of B-cell functions, even in the presence of a mixed chimerism, further validating the clinical application of the w1.6W lentiviral vector.
  The Journal of allergy and clinical immunology 06/2011; 127(6):1376-84.e5. · 9.17 Impact Factor
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  Available from: Silvia Giliani

  Article: Abnormalities of thymic stroma may contribute to immune dysregulation in murine models of leaky severe combined immunodeficiency.

  Francesca Rucci, Pietro Luigi Poliani, Stefano Caraffi, Tiziana Paganini, Elena Fontana, Silvia Giliani, Frederick W Alt, Luigi Daniele Notarangelo
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  ABSTRACT: Lymphostromal cross-talk in the thymus is essential to allow generation of a diversified repertoire of T lymphocytes and to prevent autoimmunity by self-reactive T cells. Hypomorphic mutations in genes that control T cell development have been associated with immunodeficiency and immune dysregulation both in humans and in mice. We have studied T cell development and thymic stroma architecture and maturation in two mouse models of leaky severe combined immune deficiency, carrying hypomorphic mutations in rag1 and lig4 genes. Defective T cell development was associated with abnormalities of thymic architecture that predominantly affect the thymic medulla, with reduction of the pool of mature medullary thymic epithelial cells (mTECs). While the ability of mTECs to express autoimmune regulator (Aire) is preserved in mutant mice, the frequency of mature mTECs expressing Aire and tissue-specific antigens is severely reduced. Similarly, the ability of CD4(+) T cells to differentiate into Foxp3(+) natural regulatory T cells is preserved in rag1 and lig4 mutant mice, but their number is greatly reduced. These data indicate that hypomorphic defects in T cell development may cause defective lymphostromal cross-talk and impinge on thymic stromal cells maturation, and thus favor immune dysregulation.
  Frontiers in immunology. 05/2011; 2(15).
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  Available from: PubMed Central

  Article: Absence of Rac1 and Rac3 GTPases in the nervous system hinders thymic, splenic and immune-competence development.

  Veronica Basso, Sara Corbetta, Sara Gualdoni, Diletta Tonoli, Pietro Luigi Poliani, Francesca Sanvito, Claudio Doglioni, Anna Mondino, Ivan de Curtis
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  ABSTRACT: The nervous system influences organ development by direct innervation and the action of hormones. We recently showed that the specific absence of Rac1 in neurons (Rac1(N) ) in a Rac3-deficient (Rac3(KO) ) background causes motor behavioural defects, epilepsy, and premature mouse death around postnatal day 13. We report here that Rac1(N) /Rac3(KO) mice display a progressive loss of immune-competence. Comparative longitudinal analysis of lymphoid organs from control, single Rac1(N) or Rac3(KO) , and double Rac1(N) /Rac3(KO) mutant animals showed that thymus development is preserved up to postnatal day 9 in all animals, but is impaired in Rac1(N) /Rac3(KO) mice at later times. This is evidenced by a drastic reduction in thymic cell numbers. Cell numbers were also reduced in the spleen, leading to splenic tissue disarray. Organ involution occurs in spite of unaltered thymocyte and lymphocyte subset composition, and proper mature T-cell responses to polyclonal stimuli in vitro. Suboptimal thymus innervation by tau-positive neuronal terminals possibly explains the suboptimal thymic output and arrested thymic development, which is accompanied by higher apoptotic rates. Our results support a role for neuronal Rac1 and Rac3 in dictating proper lymphoid organ development, and suggest the existence of lymphoid-extrinsic mechanisms linking neural defects to the loss of immune-competence.
  European Journal of Immunology 03/2011; 41(5):1410-9. · 5.10 Impact Factor
• Article: Targeting Notch pathway induces growth inhibition and differentiation of neuroblastoma cells.

  Giulia Ferrari-Toninelli, Sara Anna Bonini, Daniela Uberti, Laura Buizza, Paola Bettinsoli, Pietro Luigi Poliani, Fabio Facchetti, Maurizio Memo
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  ABSTRACT: High-risk neuroblastoma is a severe pediatric tumor characterized by poor prognosis. Understanding the molecular mechanisms involved in tumor development and progression is strategic for the improvement of pharmacological therapies. Notch was recently proposed as a pharmacological target for the therapy of several cancers and is emerging as a new neuroblastoma-related molecular pathway. However, the precise role played by Notch in this cancer remains to be studied extensively. Here, we show that Notch activation by the Jagged1 ligand enhances the proliferation of neuroblastoma cells, and we propose the possible use of Notch-blocking γ-secretase inhibitors (GSIs) in neuroblastoma therapy. Two different GSIs, Compound E and DAPT, were tested alone or in combination with 13-cis retinoic acid (RA) on neuroblastoma cell lines. SH-SY5Y and IMR-32 cells were chosen as paradigms of lower and higher malignancy, respectively. Used alone, GSIs induced complete cell growth arrest, promoted neuronal differentiation, and significantly reduced cell motility. The combination of GSIs and 13-cis RA resulted in the enhanced growth inhibition, differentiation, and migration of neuroblastoma cells. In summary, our data suggest that a combination of GSIs with 13-cis RA offers a therapeutic advantage over a single agent, indicating a potential novel therapy for neuroblastoma.
  Neuro-Oncology 12/2010; 12(12):1231-43. · 5.72 Impact Factor
• Article: Caveolin 1 is a marker of poor differentiation in Rhabdomyosarcoma.

  Stefania Rossi, Pietro Luigi Poliani, Manuela Cominelli, Andrea Bozzato, Raffaella Vescovi, Eugenio Monti, Alessandro Fanzani
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  ABSTRACT: Caveolins consist of three different membrane scaffolding proteins that play a variety of processes in different tissues. In skeletal muscle caveolins are differentially distributed, with Caveolin 1 (Cav-1) being uniquely expressed in satellite cells and Caveolin 3 (Cav-3) in mature myofibers. Rhabdomyosarcoma (RMS) represents the most common childhood soft-tissue sarcoma arising from mesenchimal precursors which fail to undergo proper commitment to muscle lineage. Cav-3 has been proposed as a marker of RMS with a high degree of differentiation, while biological significance of Cav-1 expression in RMS is still a matter of debate. In the present study we show that Cav-1 is predominantly expressed in the embryonal RMS histotype, as further confirmed by transcript and protein analysis in different in vitro human RMS cell lines. Immature cell phenotype of human embryonal RD line, carrying spontaneous activating RAS mutations, was significantly associated to ERK MAPK signalling pathway and featured by high Cav-1 levels, whereas pharmacological attenuation of the ERK pathway, improving cell differentiation, lead to Cav-1 down-regulation. Overall, these data place Cav-1 as a valuable marker of diagnosis for RMS characterised by low degree of differentiation.
  European journal of cancer (Oxford, England: 1990) 11/2010; 47(5):761-72. · 4.12 Impact Factor
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  Available from: Mirjam van der Burg

  Article: Homeostatic expansion of autoreactive immunoglobulin-secreting cells in the Rag2 mouse model of Omenn syndrome.

  Barbara Cassani, Pietro Luigi Poliani, Veronica Marrella, Francesca Schena, Aisha V Sauer, Maria Ravanini, Dario Strina, Christian E Busse, Stephan Regenass, Hedda Wardemann, Alberto Martini, Fabio Facchetti, Mirjam van der Burg, Antonius G Rolink, Paolo Vezzoni, Fabio Grassi, Elisabetta Traggiai, Anna Villa
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  ABSTRACT: Hypomorphic RAG mutations, leading to limited V(D)J rearrangements, cause Omenn syndrome (OS), a peculiar severe combined immunodeficiency associated with autoimmune-like manifestations. Whether B cells play a role in OS pathogenesis is so far unexplored. Here we report the detection of plasma cells in lymphoid organs of OS patients, in which circulating B cells are undetectable. Hypomorphic Rag2(R229Q) knock-in mice, which recapitulate OS, revealed, beyond severe B cell developmental arrest, a normal or even enlarged compartment of immunoglobulin-secreting cells (ISC). The size of this ISC compartment correlated with increased expression of Blimp1 and Xbp1, and these ISC were sustained by elevated levels of T cell derived homeostatic and effector cytokines. The detection of high affinity pathogenic autoantibodies toward target organs indicated defaults in B cell selection and tolerance induction. We hypothesize that impaired B cell receptor (BCR) editing and a serum B cell activating factor (BAFF) abundance might contribute toward the development of a pathogenic B cell repertoire in hypomorphic Rag2(R229Q) knock-in mice. BAFF-R blockade reduced serum levels of nucleic acid-specific autoantibodies and significantly ameliorated inflammatory tissue damage. These findings highlight a role for B cells in OS pathogenesis.
  Journal of Experimental Medicine 07/2010; 207(7):1525-40. · 13.85 Impact Factor
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  Available from: Tim Niehues

  Article: Expansion of immunoglobulin-secreting cells and defects in B cell tolerance in Rag-dependent immunodeficiency

  Jolan E. Walter, Francesca Rucci, Laura Patrizi, Mike Recher, Stephan Regenass, Tiziana Paganini, Marton Keszei, Itai Pessach, Philipp A. Lang, Pietro Luigi Poliani, [......], Hamid M. Alenezi, Javier Chinen, Ghassan Dbaibo, Gehad ElGhazali, Adriano Fontana, Srdjan Pasic, Cynthia Detre, Cox Terhorst, Frederick W. Alt, Luigi D. Notarangelo
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  ABSTRACT: The contribution of B cells to the pathology of Omenn syndrome and leaky severe combined immunodeficiency (SCID) has not been previously investigated. We have studied a mut/mut mouse model of leaky SCID with a homozygous Rag1 S723C mutation that impairs, but does not abrogate, V(D)J recombination activity. In spite of a severe block at the pro–B cell stage and profound B cell lymphopenia, significant serum levels of immunoglobulin (Ig) G, IgM, IgA, and IgE and a high proportion of Ig-secreting cells were detected in mut/mut mice. Antibody responses to trinitrophenyl (TNP)-Ficoll and production of high-affinity antibodies to TNP–keyhole limpet hemocyanin were severely impaired, even after adoptive transfer of wild-type CD4+ T cells. Mut/mut mice produced high amounts of low-affinity self-reactive antibodies and showed significant lymphocytic infiltrates in peripheral tissues. Autoantibody production was associated with impaired receptor editing and increased serum B cell–activating factor (BAFF) concentrations. Autoantibodies and elevated BAFF levels were also identified in patients with Omenn syndrome and leaky SCID as a result of hypomorphic RAG mutations. These data indicate that the stochastic generation of an autoreactive B cell repertoire, which is associated with defects in central and peripheral checkpoints of B cell tolerance, is an important, previously unrecognized, aspect of immunodeficiencies associated with hypomorphic RAG mutations.
  Journal of Experimental Medicine 07/2010; 207(7):1541-1554. · 13.85 Impact Factor
• Article: Intra-tumoral dendritic cells increase efficacy of peripheral vaccination by modulation of glioma microenvironment.

  Serena Pellegatta, Pietro Luigi Poliani, Elena Stucchi, Daniela Corno, Chiara Agnese Colombo, Francesca Orzan, Maria Ravanini, Gaetano Finocchiaro
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  ABSTRACT: Pilot data showed that adding intratumoral (IT) injection of dendritic cells (DCs) prolongs survival of patients affected by glioblastoma multiforme (GBM) treated by subcutaneous (SC) delivery of DCs. Using a murine model resembling GBM, we investigated the immunological mechanisms underlying this effect. C57BL6/N mice received brain injections of GL261 glioma cells. Seven days later, mice were treated by 3 SC injections of DCs with or without 1 IT injection of DCs. DC maturation, induced by pulsing with GL261 lysates, was necessary to develop effective immune responses. IT injection of pulsed (pDC), but not unpulsed DCs (uDC), increased significantly the survival, either per se or in combination with SC-pDC (P < .001 vs controls). Mice treated by IT-pDC plus SC-pDC survived longer than mice treated by SC-pDC only (P = .03). Injected pDC were detectable in tumor parenchyma, but not in cervical lymph nodes. In gliomas injected with IT-pDC, CD8+ cells were significantly more abundant and Foxp3+ cells were significantly less abundant than in other groups. Using real-time polymerase chain reaction, we also found enhanced expression of IFN-gamma and TNF-alpha and decreased expression of transforming growth factor-beta (TGF-beta) and Foxp3 in mice treated with SC-pDC and IT-pDC. In vitro, pDC produced more TNF-alpha than uDC: addition of TNF-alpha to the medium decreased the proliferation of glioma cells. Overall, the results suggest that IT-pDC potentiates the anti-tumor immune response elicited by SC-pDC by pro-immune modulation of cytokines in the tumor microenvironment, decrease of Treg cells, and direct inhibition of tumor proliferation by TNF-alpha.
  Neuro-Oncology 04/2010; 12(4):377-88. · 5.72 Impact Factor
• Article: Human peripheral lymphoid tissues contain autoimmune regulator-expressing dendritic cells.

  Pietro Luigi Poliani, Kai Kisand, Veronica Marrella, Maria Ravanini, Luigi Daniele Notarangelo, Anna Villa, Pärt Peterson, Fabio Facchetti
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  ABSTRACT: Autoimmune regulator (AIRE) modulates the expression of tissue-restricted antigens (TSAs) and promotes central tolerance in the thymus. However, few autoreactive T cells escape negative selection and reach the periphery, where peripheral tolerance is required to avoid autoimmunity. Murine lymph nodes (LNs) have been shown to contain "stromal" cells expressing AIRE and TSAs. Here we report the occurrence of AIRE-expressing cells in human peripheral lymphoid tissues, including LNs, tonsils, and gut-associated lymphoid tissue, with the exception of the spleen. Notably, AIRE+ cells are absent in fetal LNs and, in postnatal life, they are more numerous in abdominal than in superficial LNs, thus suggesting that their development in periphery may depend on instructive signals from microenvironment and antigen challenge. Extrathymic AIRE+ cells show a dendritic morphology, consistently express human leukocyte antigen-DR (HLADR) and fascin, and are largely positive for CD11c and S100 and for the dendritic cell-activation markers CD40, CD83, DC-LAMP/CD208, and CCR7. Lymphoid, myelomonocytic, mesenchymal, and epithelial cell lineage markers are negative. The HLADRhigh/AIRE+ cell fraction isolated from mesenteric LNs expressed TSAs (insulin, CYP17A1, and CYP21A2), as well as molecules associated with tolerogenic functions, such as interleukin-10 and indoleamine 2,3-dioxygenase. Data indicate that AIRE+ cells in human peripheral lymphoid tissues correspond to a subset of activated interdigitating dendritic cells expressing TSAs and the tolerogenic molecules indoleamine 2,3-dioxygenase and interleukin-10, suggestive of a potential tolerogenic function.
  American Journal Of Pathology 03/2010; 176(3):1104-12. · 4.89 Impact Factor
• Article: Homozygous DNA ligase IV R278H mutation in mice leads to leaky SCID and represents a model for human LIG4 syndrome.

  Francesca Rucci, Luigi D Notarangelo, Alex Fazeli, Laura Patrizi, Thomas Hickernell, Tiziana Paganini, Kristen M Coakley, Cynthia Detre, Marton Keszei, Jolan E Walter, [......], Pietro Luigi Poliani, Jing H Wang, Barbara B Balter, Mike Recher, Emma-Maria Andersson, Shan Zha, Silvia Giliani, Cox Terhorst, Frederick W Alt, Catherine T Yan
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  ABSTRACT: DNA ligase IV (LIG4) is an essential component of the nonhomologous end-joining (NHEJ) repair pathway and plays a key role in V(D)J recombination. Hypomorphic LIG4 mutations in humans are associated with increased cellular radiosensitivity, microcephaly, facial dysmorphisms, growth retardation, developmental delay, and a variable degree of immunodeficiency. We have generated a knock-in mouse model with a homozygous Lig4 R278H mutation that corresponds to the first LIG4 mutation reported in humans. The phenotype of homozygous mutant mice Lig4(R278H/R278H) (Lig4(R/R)) includes growth retardation, a decreased life span, a severe cellular sensitivity to ionizing radiation, and a very severe, but incomplete block in T and B cell development. Peripheral T lymphocytes show an activated and anergic phenotype, reduced viability, and a restricted repertoire, reminiscent of human leaky SCID. Genomic instability is associated with a high rate of thymic tumor development. Finally, Lig4(R/R) mice spontaneously produce low-affinity antibodies that include autoreactive specificities, but are unable to mount high-affinity antibody responses. These findings highlight the importance of LIG4 in lymphocyte development and function, and in genomic stability maintenance, and provide a model for the complex phenotype of LIG4 syndrome in humans.
  Proceedings of the National Academy of Sciences 02/2010; 107(7):3024-9. · 9.68 Impact Factor
• Article: Defect of regulatory T cells in patients with Omenn syndrome.

  Barbara Cassani, Pietro Luigi Poliani, Daniele Moratto, Cristina Sobacchi, Veronica Marrella, Laura Imperatori, Donatella Vairo, Alessandro Plebani, Silvia Giliani, Paolo Vezzoni, Fabio Facchetti, Fulvio Porta, Luigi D Notarangelo, Anna Villa, Raffaele Badolato
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  ABSTRACT: Omenn syndrome (OS) is an autosomal-recessive disorder characterized by severe immunodeficiency and T-cell-mediated autoimmunity. The disease is caused by hypomorphic mutations in recombination-activating genes that hamper the process of Variable (V) Diversity (D) Joining (J) recombination, leading to the generation of autoreactive T cells. We have previously shown that in OS the expression of autoimmune regulator, a key factor governing central tolerance, is markedly reduced. Here, we have addressed the role of peripheral tolerance in the disease pathogenesis. We have analyzed forkhead box protein P3 (FOXP3) expression in peripheral blood T cells of 4 patients with OS and in lymphoid organs of 8 patients with OS and have tested the suppressive activity of sorted CD4(+) CD25(high) peripheral blood T cells in 2 of these patients. We have observed that CD4(+)CD25(high)T cells isolated ex vivo from patients with OS failed to suppress proliferation of autologous or allogenic CD4(+) responder T cells. Moreover, despite individual variability in the fraction of circulating FOXP3(+) CD4 cells in patients with OS, the immunohistochemical analysis of FOXP3 expression in lymph nodes and thymus of patients with OS demonstrated a severe reduction of this cell subset compared with control tissues. Overall, these results suggest a defect of regulatory T cells in OS leading to a breakdown of peripheral tolerance, which may actively concur to the development of autoimmune manifestations in the disease.
  The Journal of allergy and clinical immunology 01/2010; 125(1):209-16. · 9.17 Impact Factor
• Article: Thymus microenvironment in human primary immunodeficiency diseases.

  Pietro Luigi Poliani, William Vermi, Fabio Facchetti
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  ABSTRACT: Severe combined immunodeficiencies represent a heterogeneous group of genetic disorders affecting genes of both early and late steps in lymphocytes development, a process tightly controlled by thymic epithelial cells. Detailed analysis of thymic morphology aids to the assessment of the severity of the immune disorder and may be critical to the understanding of the role of the genetic defects in the pathophysiology of these diseases. In this review, we highlight recent advancements in the characterization of the thymic microenvironment in primary immunodeficiencies. Crosstalk between thymocytes and thymic epithelial cells is essential to preserve thymic architecture and function, and therefore to promote T-cell maturation and development of self-tolerance. Early severe defects in T-cell development result in profound abnormalities of thymic epithelial cells differentiation with loss of AIRE expression and severe reduction of thymic dendritic and T-regulatory cells. Differently, later defects in T-cell development that are permissive for normal thymocytes development allow cortico-medullary differentiation with partially preserved AIRE expression and dendritic/T-regulatory cells distribution. Hypomorphic mutations in the same genes partially permissive to T-cell development may result in a more complex phenotype with immunodysreactivity and peculiar thymic alterations. Although the molecular and genetic bases of primary immunodeficiencies directly aid to both diagnosis and management of the patients, the detailed analysis of thymic morphology critically contributes to unveil the pathophysiology of these diseases.
  Current Opinion in Allergy and Clinical Immunology 12/2009; 9(6):489-95. · 4.11 Impact Factor
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  Available from: Silvia Lonardi

  Article: Cutaneous distribution of plasmacytoid dendritic cells in lupus erythematosus. Selective tropism at the site of epithelial apoptotic damage.

  William Vermi, Silvia Lonardi, Mauro Morassi, Cristina Rossini, Regina Tardanico, Marina Venturini, Raffaella Sala, Angela Tincani, Pietro Luigi Poliani, Pier Giacomo Calzavara-Pinton, Lorenzo Cerroni, Amerigo Santoro, Fabio Facchetti
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  ABSTRACT: Recent evidences suggest a significant role of Plasmacytoid dendritic cells (PDC) role in the pathogenesis of lupus erythematosus (LE) via production of type I IFN. Taking advantage on the availability of multiple reagents (CD123, BDCA2, and CD2ap) specifically recognizing PDC on fixed tissues, we investigated the occurrence of PDC in a cohort of 74 LE patients. The large majority of LE biopsies (67/74; 90.5%) showed cutaneous infiltration of PDC. PDC were more frequently observed (96.4 vs 72.2) and numerous in cutaneous LE compared to systemic LE (SLE) and correlated with the density of the inflammatory infiltrate (r=0.40; p<0.001). PDC reduction in SLE might be related to a broader tissue distribution of this cellular population, as indicated by their occurrence in kidneys in 11 out of 24 (45.8%) cases studied. The distribution of cutaneous PDC showed two distinct patterns. More commonly, PDC were observed within perivascular inflammatory nodules in the dermis, associated with CD208+ mature DC and T-bet+ cells [D-PDC]. A second component was observed along the dermal-epithelial junction [J-PDC], in association with cytotoxic T-cells in areas of severe epithelial damage. Notably, chemerin reactivity was observed in 64% of LE biopsies on endothelial cells and in the granular layer keratinocytes. Cutaneous PDC in LE strongly produced type I IFN, as indicated by the diffuse MxA expression, and the cytotoxic molecule granzyme B. This study confirms cutaneous PDC infiltration as hallmark of LE. The topographical segregation in D-PDC and J-PDC suggests a novel view of the role of these cells in skin autoimmunity.
  Immunobiology 08/2009; 214(9-10):877-86. · 3.20 Impact Factor