Aim: To investigate the mechanism of the tight junction (TJ) disruption and the association between tumor necrosis factor (TNF)-α and matrix metalloproteinase (MMPs) under hyperosmotic condition in primary human corneal epithelial cells (HCECs).
Methods: The cultured HCECs were exposed to media which adding sodium chloride (NaCl) for hyperosmolar stress or adding rh-TNF-α (10 ng/mL). NF-κB inhibitor (5 µmol/L) or GM-6001 (potent and broad spectrum MMP inhibitor, 20 µmol/L) was added 1h before that treatment. The integrity of TJ proteins was determined by immunofluorescent (IF) staining. The mRNA levels of TNF-α and MMPs were evaluated by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and the protein expression by enzyme-linked immunosorbent assay (ELISA).
Results: TJ proteins ZO-1 and Occludin were disrupted in primary HCECs exposed to hyperosmotic medium. The mRNA expression and protein production of TNF-α increased significantly in hyperosmotic media at 500 mOsM. TNF-α mediated the expression and production of MMP-1, MMP-13, MMP-9, and MMP-3 stimulated by hyperosmotic stress. The production of MMPs in hyperosmolar media were increased through the increase of TNF-α. GM-6001 prevent the destruction of ZO-1 and Occludin in hyperosmolar stress and rh-TNF-α treated medium. TNF-α induced activation of MMPs was involved in the TJ disruption by hyperosmolarity.
Conclusion: TJ proteins ZO-1 and Occludin are disrupted by hyperosmolar stress and TNF-α, but protected by MMP inhibitor (GM-6001). It suggests that TNF-α/MMP pathway mediates the TJ disruption in primary HCECs exposed to hyperosmotic stress.
Keywords: cornea epithelium; dry eye; hyperosmolarity; tight junction.
International Journal of Ophthalmology Press.