title: Extracellular high mobility group box-1 inhibits R5 and X4 HIV-1 strains replication in mononuclear phagocytes without induction of chemokines and cytokines.
abstract: OBJECTIVE
  High mobility group box-1 (HMGB1) is a nuclear chromatin protein. Furthermore, it induces chemotaxis and inflammation once released in the extracellular milieu, and it has been reported to upregulate, but also to inhibit HIV-1 replication in different cell types. We here investigated the potential role of extracellular HMGB1 in both R5 and X4 HIV-1 replication in primary human monocyte-derived macrophages (MDM) and U937 promonocytic cells, respectively.
  
  
  METHODS
  MDM or U937 cells were infected with R5 and X4 HIV-1 strains, respectively, in the presence or absence of endotoxin-free recombinant (r) HMGB1 or necrotic cell supernatants either containing or depleted of endogenous HMGB1.
  
  
  METHODS
  HIV replication was measured by means of virion-associated reverse transcriptase activity in culture supernatants and cell-associated viral protein expression. Cytokine and chemokine production were measured by enzyme-linked immunosorbent assay; cell surface expression of CD4, CC chemokine receptor 5, receptor for advanced glycation end-products, Toll-like receptor-2 and Toll-like receptor-4 were analyzed by flow cytometry.
  
  
  RESULTS
  Both rHMGB1 and necrotic cell supernatant-associated HMGB1 inhibited replication of R5 HIV-1 in MDM. Surprisingly enough, no upregulation of CC chemokine receptor 5-binding chemokines or of other chemokines and cytokines was observed in rHMGB1-stimulated MDM. HMGB1 also induced chemotaxis and strongly inhibited the replication of X4 HIV-1 in the 'Minus' subset of U937 cell clones expressing high levels of putative HMGB1 receptors (receptor for advanced glycation end-products, Toll-like receptors 2 and 4).
  
  
  CONCLUSIONS
  Extracellular HMGB1 is a potent inhibitor of both R5 and X4 HIV-1 replication in mononuclear phagocytic cells without inducing the release of HIV-Modulatory chemokines or cytokines.
authors.affiliation: AIDS Immunopathogenesis, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Cassetta
authors.forename: Orazio
authors.initials: O
authors.lastname: Fortunato
authors.forename: Leda
authors.initials: L
authors.lastname: Adduce
authors.forename: Chiara
authors.initials: C
authors.lastname: Rizzi
authors.forename: Julia
authors.initials: J
authors.lastname: Hering
authors.forename: Patrizia
authors.initials: P
authors.lastname: Rovere-Querini
authors.forename: Marco Emilio
authors.initials: ME
authors.lastname: Bianchi
authors.forename: Massimo
authors.initials: M
authors.lastname: Alfano
authors.forename: Guido
authors.initials: G
authors.lastname: Poli
mesh_terms: D000818:Animals; D019380:Anti-HIV Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D018925:Chemokines / Q000096:biosynthesis; D002633:Chemotaxis / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis; D004353:Drug Evaluation, Preclinical / Q000379:methods; D015658:HIV Infections / Q000276:immunology / Q000821:virology*; D015497:HIV-1 / Q000187:drug effects* / Q000502:physiology; D024243:HMGB1 Protein / Q000494:pharmacology* / Q000502:physiology; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000821:virology*; D051379:Mice; D055017:Monocyte-Macrophage Precursor Cells / Q000187:drug effects / Q000276:immunology / Q000821:virology; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D020298:U937 Cells; D014779:Virus Replication / Q000187:drug effects
chemical_list: D019380:Anti-HIV Agents; D018925:Chemokines; D016207:Cytokines; D024243:HMGB1 Protein; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D011994:Recombinant Proteins; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4