Supernatants of HIV-infected immune cells affect the barrier function of human HT-29/B6 intestinal epithelial cells.
OBJECTIVE
Characterization of the diarrhoea-inducing effect of altered cytokine production in HIV infection.


METHODS
Monocyte-derived macrophages (MDM) were infected with macrophagetropic (SF162) and lymphocytotropic (IIIB) HIV-1 strains and cocultured with autologous peripheral blood mononuclear cells (PBMC). After 24 h the supernatants were collected and tested for their immunoreactive levels of cytokines by enzyme-linked immunosorbent assay. The effects of the supernatants and the respective recombinant human cytokines on barrier function of HT-29/B6 cells were determined.


RESULTS
Infection of MDM with HIV-1 SF162 or IIIB led to increased production of tumour necrosis factor-alpha (TNFalpha), interleukin-1-beta, interferon-alpha and interferon-gamma after cell-cell contact with PBMC. Supernatants of infected cells decreased transepithelial resistance (R(t)), with higher effects on R(t) in HIV IIIB infection, which was due to higher cytokine concentrations. The effect was not due to cytotoxicity (negative LDH assay) or epithelial monolayer disruption [zonula occludens protein-1 (ZO-1) immunofluorescence staining]. The effect of HIV-1 IIIB coculture supernatants could be mimicked by the respective recombinant human cytokines. TNFalpha is an effector cytokine, because inhibition of TNFalpha by its soluble receptor decreased the effect of the supernatants on transepithelial resistance. Conductance scanning indicated the cytokine-induced barrier defect to be due to both, induction of epithelial apoptoses and tight junction alterations.


CONCLUSIONS
Cell-cell interaction of HIV-infected macrophages with PBMC leads to a release of cytokines sufficient to alter intestinal epithelial barrier function. The main effect was mediated by TNFalpha inducing a leak-flux which may contribute to the diarrhoea by HIV per se (HIV-enteropathy).
Schmitz
Heinz
H
Department of Gastroenterology, Infectious Diseases and Rheumatology, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, 12200 Berlin, Germany.
Rokos
Katharina
K
Florian
Peter
P
Gitter
Alfred H
AH
Fromm
Michael
M
Scholz
Peter
P
Ullrich
Reiner
R
Zeitz
Martin
M
Pauli
Georg
G
Schulzke
Jörg-Dieter
JD
D017209:Apoptosis; D002450:Cell Communication; D002478:Cells, Cultured / Q000378:metabolism / Q000821:virology; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism / Q000494:pharmacology*; D003967:Diarrhea / Q000209:etiology*; D017097:Electric Impedance; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D015658:HIV Infections / Q000150:complications*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism / Q000821:virology*; D008565:Membrane Proteins / Q000032:analysis; D010539:Permeability; D010750:Phosphoproteins / Q000032:analysis; D011994:Recombinant Proteins / Q000494:pharmacology; D019108:Tight Junctions / Q000187:drug effects* / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology; D062826:Zonula Occludens-1 Protein
D017077:Culture Media, Conditioned; D016207:Cytokines; D008565:Membrane Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; C569042:TJP1 protein, human; D014409:Tumor Necrosis Factor-alpha; D062826:Zonula Occludens-1 Protein