The nuclear-factor kappaB pathway is activated in pterygium.
OBJECTIVE
Pterygium is a prevalent ocular surface disease with unknown pathogenesis. The authors investigated the role of nuclear factor kappa B (NF-κB) transcription factors in pterygium.


METHODS
Surgically excised primary pterygia were studied compared with uninvolved conjunctiva tissues. NF-κB activation was evaluated using Western blot analysis, ELISA, and DNA-binding assays. Primary pterygium fibroblasts were treated with TNF-α (20 ng/mL), and NF-κB activation was evaluated using immunocytochemistry, Western blot analysis, phospho-IκBα ELISA, and DNA-binding assays. TNF-α stimulation of NF-κB target genes RelB, NFKB2, RANTES, MCP-1, ENA-78, MMP-1, MMP-2, and MMP-3 in pterygium fibroblasts was compared with that in primary tenon fibroblasts by real-time PCR.


RESULTS
Phosphorylation of IκBα (Ser32) was increased in pterygia tissues compared with uninvolved conjunctiva tissues, as determined by Western blot analysis and ELISA. IκBα expression was decreased, whereas nuclear RelA and p50 DNA-binding capacities were increased. Within 30 minutes of treatment with TNF-α, pterygium fibroblasts showed increased IκBα phosphorylation and nuclear translocation of RelA and p50. Treatment with TNF-α beyond 12 hours resulted in increased nuclear expression of RelB, p100, and p52. Furthermore, the upregulation of RANTES, MCP-1, ENA-78, MMP-1, MMP-2, and MMP-3 expression was more pronounced in TNF-α-treated pterygium fibroblasts than in tenon fibroblasts.


CONCLUSIONS
The NF-κB pathway is shown for the first time to be activated in pterygia tissues compared with normal conjunctiva tissues. Stimulation by the inflammatory cytokine TNF-α can activate both canonical and noncanonical NF-κB pathways in pterygium fibroblasts with concomitant upregulation of NF-κB target genes.
Siak
Jay Jyh Kuen
JJ
Singapore National Eye Centre, Singapore.
Ng
See Liang
SL
Seet
Li-Fong
LF
Beuerman
Roger W
RW
Tong
Louis
L
D015153:Blotting, Western; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D018946:Chemokine CCL5 / Q000378:metabolism; D054365:Chemokine CXCL5 / Q000378:metabolism; D003228:Conjunctiva / Q000166:cytology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011625:Pterygium / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
C111835:CCL2 protein, human; C483024:CCL5 protein, human; C486263:CXCL5 protein, human; D018932:Chemokine CCL2; D018946:Chemokine CCL5; D054365:Chemokine CXCL5; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D020782:Matrix Metalloproteinases