Glucosamine sulfate inhibits proinflammatory cytokine-induced icam-1 production in human conjunctival cells in vitro.
OBJECTIVE
We investigated whether glucosamine sulfate modulates the production of ICAM-1 induced by proinflammatory cytokines and whether glucosamine sulfate inhibits leukocyte adhesion to a monolayer of human conjunctival epithelial cells stimulated with proinflammatory cytokines.


METHODS
We used flow cytometry and either primary cultured human conjunctival cells or the Chang conjunctival cell model to determine the effects of glucosamine sulfate on the production of ICAM-1 in response to tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1beta, IL-6, TNF-alpha plus IFN-gamma, or TNF-alpha plus IL-1beta. The effects of glucosamine sulfate on the expression of the ICAM-1 gene, upregulated by various cytokines, were determined by semiquantitative reverse transcription-polymerase chain reaction. The activation and nuclear translocation of the nuclear factors NF-kappaB and STAT1 were evaluated by the transient transfection of reporter gene systems and immunocytochemistry. The influence of glucosamine-sulfate-modulated ICAM-1 on neutrophil adhesion was demonstrated in a model that measures the adherence of conjunctival cells and neutrophils.


RESULTS
TNF-alpha, IFN-gamma, and IL-1beta significantly increased the production of ICAM-1 by both primary cultured human conjunctival cells and Chang conjunctival cells. Glucosamine sulfate effectively downregulated the production of ICAM-1 induced by TNF-alpha, IFN-gamma, IL-1beta, TNF-alpha plus IFN-gamma, or TNF-alpha plus IL-1beta. This downregulation occurred through the interferon-stimulated response element, IFN-gamma activation sequence, and binding sequence of NF-kappaB at the mRNA and protein levels. Glucosamine sulfate further inhibited the nuclear translocation of p65 protein in TNF-alpha- and IL-1beta-stimulated Chang conjunctival cells and phosphorylated STAT1 in IFN-gamma-stimulated Chang conjunctival cells. Glucosamine sulfate also significantly reduced the number of neutrophils adhering to a conjunctival monolayer in response to TNF-alpha, IFN-gamma, or IL-1beta.


CONCLUSIONS
Our results suggest that glucosamine sulfate inhibits ICAM-1 production in conjunctival epithelial cells in vitro. Therefore, glucosamine sulfate might be valuable in the treatment of inflammatory ocular-surface conditions.
Chen
Jiann-Torng
JT
Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China. jt66chen@ms32.hinet.net
Chen
Chiao-Hong
CH
Horng
Chi-Ting
CT
Chien
Ming-Wei
MW
Lu
Da-Wen
DW
Liang
Jy-Been
JB
Tai
Ming-Cheng
MC
Chang
Yun-Hsiang
YH
Chen
Po Liang
PL
Chen
Yi-Hao
YH
D000328:Adult; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D003228:Conjunctiva / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000276:immunology*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter; D005944:Glucosamine / Q000494:pharmacology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis* / Q000235:genetics; D009504:Neutrophils / Q000166:cytology; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050794:STAT1 Transcription Factor / Q000096:biosynthesis
D016207:Cytokines; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D018799:Intercellular Adhesion Molecule-1; D005944:Glucosamine