title: Neutrophil gelatinase-associated lipocalin increases HLA-G(+)/FoxP3(+) T-regulatory cell population in an in vitro model of PBMC.
abstract: BACKGROUND
  Neutrophil gelatinase-associated lipocalin (NGAL) is emerging as a mediator of various biological and pathological states. However, the specific biological role of this molecule remains unclear, as it serves as a biomarker for many conditions. The high sensitivity of NGAL as a biomarker coupled with relatively low specificity may hide important biological roles. Data point toward an acute compensatory, protective role for NGAL in response to adverse cellular stresses, including inflammatory and oxidative stress. The aim of this study was to understand whether NGAL modulates the T-cell response through regulation of the human leukocyte antigen G (HLA-G) complex, which is a mediator of tolerance.
  
  
  RESULTS
  Peripheral blood mononuclear cells (PBMCs) were obtained from eight healthy donors and isolated by centrifugation on a Ficoll gradient. All donors gave informed consent. PBMCs were treated with four different concentrations of NGAL (40-320 ng/ml) in an iron-loaded or iron-free form. Changes in cell phenotype were analyzed by flow cytometry. NGAL stimulated expression of HLA-G on CD4+ T cells in a dose- and iron-dependent manner. Iron deficiency prevented NGAL-mediated effects, such that HLA-G expression was unaltered. Furthermore, NGAL treatment affected stimulation of regulatory T cells and in vitro expansion of CD4(+) CD25(+) FoxP3(+) cells. An NGAL neutralizing antibody limited HLA-G expression and significantly decreased the percentage of CD4(+) CD25(+) FoxP3(+) cells.
  
  
  CONCLUSIONS
  We provide in vitro evidence that NGAL is involved in cellular immunity. The potential role of NGAL as an immunomodulatory molecule is based on its ability to induce immune tolerance by upregulating HLA-G expression and expansion of T-regulatory cells in healthy donors. Future studies should further evaluate the role of NGAL in immunology and immunomodulation and its possible relationship to immunosuppressive therapy efficacy, tolerance induction in transplant patients, and other immunological disorders.
authors.affiliation: Dialysis, Nephrology and Transplantation Unit, Department of Experimental, Diagnostic and Specialty Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: La Manna
authors.affiliation: Department of Internal and Experimental Medicine, Second University of Studies of Naples, Naples, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Ghinatti
authors.affiliation: Service of Immunohematology and Transfusion Medicine, Department of Hematology, Oncology and Laboratory Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Tazzari
authors.affiliation: Section of Histology, Embryology and Applied Biology, Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Alviano
authors.affiliation: Service of Immunohematology and Transfusion Medicine, Department of Hematology, Oncology and Laboratory Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Ricci
authors.affiliation: Dialysis, Nephrology and Transplantation Unit, Department of Experimental, Diagnostic and Specialty Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Capelli
authors.affiliation: Dialysis, Nephrology and Transplantation Unit, Department of Experimental, Diagnostic and Specialty Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Vania
authors.initials: V
authors.lastname: Cuna
authors.affiliation: Dialysis, Nephrology and Transplantation Unit, Department of Experimental, Diagnostic and Specialty Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Todeschini
authors.affiliation: Urology Unit, Department of Experimental, Diagnostic and Specialty Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Brunocilla
authors.affiliation: Service of Immunohematology and Transfusion Medicine, Department of Hematology, Oncology and Laboratory Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Pasqualepaolo
authors.initials: P
authors.lastname: Pagliaro
authors.affiliation: Section of Histology, Embryology and Applied Biology, Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bonsi
authors.affiliation: Dialysis, Nephrology and Transplantation Unit, Department of Experimental, Diagnostic and Specialty Medicine, St. Orsola University Hospital, Bologna, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Stefoni
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism* / Q000494:pharmacology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D004758:Enterobactin / Q000494:pharmacology; D051858:Forkhead Transcription Factors / Q000378:metabolism; D059951:HLA-G Antigens / Q000378:metabolism; D006801:Humans; D016130:Immunophenotyping; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D000071068:Lipocalin-2; D054834:Lipocalins / Q000378:metabolism* / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000378:metabolism* / Q000494:pharmacology; D016176:T-Lymphocyte Subsets; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*
chemical_list: D000209:Acute-Phase Proteins; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D059951:HLA-G Antigens; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D004758:Enterobactin