Abstract
Abstract: :
Staphylococcus aureus (SA) bacteria are found in large colony counts on the skin of 90% of patients with atopic dermatitis and could play a role in the pathophysiology of atopic keratoconjunctivitis (AKC). SA peptidoglycan (SA–PGN) can be recognized by Toll–like receptor 2 (TLR2) and Platelet Activating Factor Receptor (PAFR) expressed on epithelial cells resulting in release of pro–inflammatory cytokines such as TNFα. Purpose: To examine the roles of TLR2 and PAFR in SA–PGN mediated release of TNFα from human conjunctival epithelial cells (HCE). Methods: Primary HCE cultures were obtained by enzymatic digestion of cadaveric conjunctival tissues. TLR2 protein and mRNA expression by conjunctival epithelial cells (± IFNγ) were confirmed by flow cytometry and Northern blot analysis respectively. HCE were pre–incubated with/without TLR2 blocking antibody (A–TLR2) and/or PAFR antagonist (WEB2086) followed by stimulation with/without S. aureus PGN for 24 hrs. Supernates were harvested for TNFα ELISA. Results: HCE expressed TLR2 protein and mRNA, following stimulation with IFNγ. SA–PGN stimulated TNFα release from HCE (1504.45±340.15 vs. 700.64±126.36 pg/106 cells for SA–PGN vs. unstimulated HCE respectively, p<0.05), which was inhibited in a dose dependent manner by A–TLR2. Inhibition was 47.9 ± 8.9% of SA–PGN stimulated TNFα release (20 µg/ml dose A–TLR2, p<0.05). PAFR antagonist had no effect on SA–PGN stimulated TNFα release alone or in combination with TLR2 blocking antibody. Conclusion: SA–PGN mediated TNFα release from HCE via TLR2 may contribute to the pathogenesis of AKC and thus represent a target for treatment of this chronic ocular inflammatory disease.
Keywords: conjunctiva • inflammation • Staphylococcus