Immunology of the ocular surface and contact lens wear: theoretical fundamentals

Abstract

Abstract

Immunomodulation on the ocular surface: a review

“…Actually, the tear film, cornea, palpebral and bulbar conjunctiva, main and accessory lacrimal glands, Meibomian glands, as well as eyelids and eyelashes with the associated glands, which constitute the structural and functional components of the ocular surface, show a characteristic immune profile [ 4 – 6 ]. It was also shown that the immunomodulation of this response is possible, which helps avoiding a potential detrimental effect of the excessive response or persistent immune activation [ 5 – 7 ]. It is essential as the two partly opposing roles of the immune protection include destroying the invading pathogens and limiting the inflammatory response, which may damage delicate ocular structures at the same time [ 8 ].…”

Material, Immunological, and Practical Perspectives on Eye Drop Formulation

“…Tears lubricate and smooth the ocular surface and the components of the tear film work to trap debris (mucins), kill pathogens (lysozymes, phospholipase, etc. ), facilitate the aggregation of the neutralized foreign bodies (sIgA), and assist with the removal of said bodies through blinking 16…”

“…Mucins act to promote an optimally lubricated ocular surface by supporting the spreading of the bulk of the tear film over the corneal and conjunctival tissues. In particular, secreted, gel‐forming MUC5AC and cell adhesive MUC1 facilitate pathogen removal by trapping the pathogen and preventing its adhesion to the underlying epithelial tissue 16b,19. The longer, surface adhesive mucins also allow for the formation of reservoirs of oxidative enzymes, defensins, lysozymes, and lactoferrin—proteins produced by scavenger cells, neutrophilic granulocytes, that are attracted to inflammation—which work to reduce the adhesion of bacteria and remove damaged host tissue 16b,20.…”

“…In particular, secreted, gel‐forming MUC5AC and cell adhesive MUC1 facilitate pathogen removal by trapping the pathogen and preventing its adhesion to the underlying epithelial tissue 16b,19. The longer, surface adhesive mucins also allow for the formation of reservoirs of oxidative enzymes, defensins, lysozymes, and lactoferrin—proteins produced by scavenger cells, neutrophilic granulocytes, that are attracted to inflammation—which work to reduce the adhesion of bacteria and remove damaged host tissue 16b,20. Certain molecules are bactericidal: Gram‐negative bacteria are killed by lysozymes which split their muramic acid linkages,16a,21 whereas secretory phospholipase A2 acts against Gram‐positive bacteria,16 as do lactoferrin and transferrin which—as the names indicate—bind iron 16a,20.…”

“…The primary antibody present in tears is sIgA, which is produced in the lacrimal gland and works to prevent bacterial adhesion, aggregate neutralized pathogens, and allow clearance of the pathogens from the ocular surface 16b,26. It has also been associated with the increased chemotaxis of neutrophils and other immune cells during the prolonged period of eyelid closure during sleep 27.…”