Glucosamine sulfate inhibits TNF-alpha and IFN-gamma-induced production of ICAM-1 in human retinal pigment epithelial cells in vitro.
OBJECTIVE
Glucosamine sulfate (GS) is a naturally occurring sugar that possesses some immunosuppressive effects in vitro and in vivo, but its mechanism is unknown. We investigated whether GS could modulate the proinflammatory cytokine-induced expression of the gene for intercellular adhesion molecule (ICAM)-1, an inflammatory protein in human retinal pigment epithelial (RPE) cells.


METHODS
ARPE-19 cells were used as a model to determine the effects of GS on the expression of the ICAM-1 gene upregulated by TNF-alpha or IFN-gamma, by Western blot analysis and semiquantitative reverse transcription polymerase chain reaction (RT-PCR). The activation and nuclear translocation of the nuclear factors NF-kappaB and STAT1 were evaluated by immunocytochemistry, Western blot analysis, and electrophoretic mobility shift assay (EMSA).


RESULTS
Both TNF-alpha and IFN-gamma increased the expression of ICAM-1 at the mRNA and protein levels in a time- and dose-dependent manner in ARPE-19 cells. GS effectively downregulated the TNF-alpha- or IFN-gamma-induced expression of ICAM-1 in the protein and mRNA level in a dose-dependent manner. GS further inhibited the nuclear translocation of p65 proteins in TNF-alpha and phosphorylated STAT1 in IFN-gamma-stimulated ARPE-19 cells.


CONCLUSIONS
GS inhibits the expression of the ICAM-1 gene in ARPE-19 cell stimulated with TNF-alpha or IFN-gamma through blockade of NF-kappaB subunit p65 and nuclear translocation of STAT1. This study has demonstrated a potentially important property of GS in reducing ICAM-1 mediated inflammatory mechanisms in the eye.
Chen
Jiann-Torng
JT
Department of Ophthalmology, Tri-Service General Hospital, Taipei, Taiwan.
Liang
Jy-Been
JB
Chou
Chung-Long
CL
Chien
Ming-Wei
MW
Shyu
Ruey-Ching
RC
Chou
Ping-I
PI
Lu
Da-Wen
DW
D015153:Blotting, Western; D018929:Cell Culture Techniques; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D019084:Fluorescent Antibody Technique, Indirect; D005944:Glucosamine / Q000494:pharmacology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis* / Q000235:genetics; D007371:Interferon-gamma / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015854:Up-Regulation
D016328:NF-kappa B; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma; D005944:Glucosamine