Abstract
Purpose: :
Toll-like receptors (TLRs), pattern-recognition receptors that sense conserved pathogen-associated molecular patterns (PAMPs), are the key receptors for the recognition of microbes. TLR5 recognizes bacterial flagellin, a component protein of bacterial flagella. Flagella are present in both gram-positive and gram-negative bacteria, and are essential for bacterial motility, invasion, and chemotaxis. We previously reported that human ocular-surface epithelial cells, both corneal and conjunctival, express TLR5 and secrete pro-inflammatory cytokines in response to flagellin derived from pathogenic ocular bacteria, but not from non-pathogenic ocular bacteria. The purpose of this present study was to examine the expression of TLR5 in various ocular surface disorders.
Methods: :
Immunohistochemistry was performed on nearly normal conjunctival tissues obtained during surgery for conjunctivochalasis as a control, and on human conjunctival tissues obtained from patients undergoing surgical reconstruction of the ocular surface due to chemical eye burns, Stevens-Johnson syndrome (SJS), or ocular cicatricial pemphigoid (OCP). For TLR5 staining, mouse anti-human TLR5 monoclonal antibody (mAb; Abcam, Cambridge, UK) was used.
Results: :
TLR5 protein was consistently and abundantly expressed in human conjunctival epithelium and detected only at the basal- and wing sites in conjunctival epithelium obtained from the patients with conjunctivochalasis, indicating its spatially selective presence on the basolateral- but not the apical side. On the other hand, in the conjunctival epithelium obtained from the patients with chemical eye burns, SJS, and OCP, the TLR5 protein was detected at not only the basolateral side but also in the near apical side.
Conclusions: :
The findings of this study suggest that TLR5 protein might be up-regulated in the conjunctival epithelium of patients with chemical eye burns, SJS, or OCP.
Keywords: cornea: epithelium • conjunctiva