title: Colorectal mucus binds DC-SIGN and inhibits HIV-1 trans-infection of CD4+ T-lymphocytes.
abstract: Bodily secretions, including breast milk and semen, contain factors that modulate HIV-1 infection. Since anal intercourse caries one of the highest risks for HIV-1 transmission, our aim was to determine whether colorectal mucus (CM) also contains factors interfering with HIV-1 infection and replication. CM from a number of individuals was collected and tested for the capacity to bind DC-SIGN and inhibit HIV-1 cis- or trans-infection of CD4+ T-lymphocytes. To this end, a DC-SIGN binding ELISA, a gp140 trimer competition ELISA and HIV-1 capture/ transfer assays were utilized. Subsequently we aimed to identify the DC-SIGN binding component through biochemical characterization and mass spectrometry analysis. CM was shown to bind DC-SIGN and competes with HIV-1 gp140 trimer for binding. Pre-incubation of Raji-DC-SIGN cells or immature dendritic cells (iDCs) with CM potently inhibits DC-SIGN mediated trans-infection of CD4+ T-lymphocytes with CCR5 and CXCR4 using HIV-1 strains, while no effect on direct infection is observed. Preliminary biochemical characterization demonstrates that the component seems to be large (>100kDa), heat and proteinase K resistant, binds in a α1-3 mannose independent manner and is highly variant between individuals. Immunoprecipitation using DC-SIGN-Fc coated agarose beads followed by mass spectrometry indicated lactoferrin (fragments) and its receptor (intelectin-1) as candidates. Using ELISA we showed that lactoferrin levels within CM correlate with DC-SIGN binding capacity. In conclusion, CM can bind the C-type lectin DC-SIGN and block HIV-1 trans-infection of both CCR5 and CXCR4 using HIV-1 strains. Furthermore, our data indicate that lactoferrin is a DC-SIGN binding component of CM. These results indicate that CM has the potential to interfere with pathogen transmission and modulate immune responses at the colorectal mucosa.
authors: Laboratory of Experimental Virology, Department of Medical Microbiology, Centre for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors: Martijn J
authors: MJ
authors: Stax
authors: Laboratory of Experimental Virology, Department of Medical Microbiology, Centre for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors: Emily E I M
authors: EE
authors: Mouser
authors: Laboratory of Experimental Virology, Department of Medical Microbiology, Centre for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors: Thijs
authors: T
authors: van Montfort
authors: Laboratory of Experimental Virology, Department of Medical Microbiology, Centre for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, United States of America.
authors: Rogier W
authors: RW
authors: Sanders
authors: Department of Dermatology, Medical Centre of the University of Amsterdam, Amsterdam, The Netherlands; STI outpatient clinic, Cluster Infectious Diseases, Public Health Service Amsterdam and Centre for Infections and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors: Henry J C
authors: HJ
authors: de Vries
authors: Mass Spectrometry of Biomacromolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, the Netherlands.
authors: Henk L
authors: HL
authors: Dekker
authors: Division of Infectious Diseases, Faculty of Medicine, Imperial College, London, United Kingdom.
authors: Carolina
authors: C
authors: Herrera
authors: Department of Medical Biochemistry, Medical Centre of the University of Amsterdam, Amsterdam, the Netherlands.
authors: Dave
authors: D
authors: Speijer
authors: Laboratory of Experimental Virology, Department of Medical Microbiology, Centre for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom.
authors: Georgios
authors: G
authors: Pollakis
authors: Laboratory of Experimental Virology, Department of Medical Microbiology, Centre for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom.
authors: William A
authors: WA
authors: Paxton
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000821:virology; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D045744:Cell Line, Tumor; D003106:Colon / Q000378:metabolism*; D003713:Dendritic Cells / Q000378:metabolism; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D007781:Lactoferrin / Q000378:metabolism; D037181:Lectins, C-Type / Q000378:metabolism*; D013058:Mass Spectrometry; D009093:Mucus / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012007:Rectum / Q000378:metabolism*; D054299:env Gene Products, Human Immunodeficiency Virus / Q000378:metabolism; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
chemical_list: D015815:Cell Adhesion Molecules; D007781:Lactoferrin; D037181:Lectins, C-Type; D011956:Receptors, Cell Surface; D054299:env Gene Products, Human Immunodeficiency Virus; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin; C097729:gp140 envelope protein, Human immunodeficiency virus 1