Co-expression of CXCR4/fusin and galactosylceramide in the human intestinal epithelial cell line HT-29.
OBJECTIVE
To detect the expression CXCR4/fusin in human intestinal epithelial cells and to assess its potential role in the pathway of HIV-1 infection mediated by the alternative gp120 receptor galactosylceramide (GalCer).


METHODS
GalCer+ (HT-29, HT-29/CD4+) and GalCer- (Caco-2/Cl2, Cl14 and Cl14/CD4+) human intestinal cell lines were analysed for CXCR4/fusin expression using the monoclonal antibody (MAb) 12G5. This MAb was then evaluated for its ability to inhibit HIV-1 infection in permissive cells. HIV-1 infection was measured by detection of p24 antigen, polymerase chain reaction amplification, and cocultivation with CD4+ cells.


RESULTS
CXCR4/fusin was detected on the surface of HT-29 and HT-29/CD4+, but not on Caco-2/Cl2, Cl14 and Cl14/CD4+ cells. Ninety per cent of CXCR4/fusin+ HT-29 and HT-29/CD4+ cells co-expressed GalCer. Infection of HT-29 cells by laboratory isolates of HIV-1 was inhibited by both anti-GalCer and anti-CXCR4/fusin MAbs. Expression of CD4 rendered HT-29 cells sensitive to HIV-1(89.6), a macrophage-tropic isolate that does not recognize GalCer. The 12G5 MAb blocked HIV-1 infection of HT-29/CD4+ cells. In contrast, the expression of HIV-1 receptors, i.e., CD4 GalCer or both, into CXCR4/fusin-negative intestinal cells did not confer sensitivity to HIV-1 infection. The resulting receptor-positive cell lines could, however, bind HIV-1, whereas the original cell lines could not.


CONCLUSIONS
HIV-1 entry into human intestinal cells involves both GalCer and CXCR4/fusin. HIV-1 isolates such as 89.6 that are able to use CXCR4/fusin as coreceptor, but do not bind to GalCer, do not infect these cells. These data raise the possibility that CXCR4/fusin may function as a coreceptor for HIV-1 entry into CD4-/GalCer+ intestinal epithelial cells.
Delézay
O
O
Laboratoire de Biochimie et Biologie de la Nutrition, URA-CNRS 1820, Faculté des Sciences de St Jérôme, Marseille, France.
Koch
N
N
Yahi
N
N
Hammache
D
D
Tourres
C
C
Tamalet
C
C
Fantini
J
J
D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D015496:CD4-Positive T-Lymphocytes; D018938:Caco-2 Cells; D002478:Cells, Cultured; D004279:DNA, Viral / Q000032:analysis / Q000235:genetics; D019084:Fluorescent Antibody Technique, Indirect; D005699:Galactosylceramides / Q000378:metabolism*; D016655:HIV Core Protein p24 / Q000032:analysis; D015658:HIV Infections / Q000378:metabolism*; D015497:HIV-1; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D016133:Polymerase Chain Reaction; D019718:Receptors, CXCR4; D015728:Receptors, HIV / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D013433:Sulfoglycosphingolipids / Q000494:pharmacology
D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D004279:DNA, Viral; D005699:Galactosylceramides; D016655:HIV Core Protein p24; D008565:Membrane Proteins; D019718:Receptors, CXCR4; D015728:Receptors, HIV; D013433:Sulfoglycosphingolipids