Nerve cells in the human eye have a crucial relationship with immune cells to maintain healthy vision, new research suggests.
In a paper published in Progress in Retinal and Eye Research, researchers from the University of Birmingham in the UK and the University of Melbourne in Australia have brought together key publications on the interaction between immune and nerve cells in the cornea.
The paper describes how the unique tissue in the cornea, which has a dense network of sensory nerves and receptors that sense tissue damage, communicates with immune cells to ensure cooperation to keep the cornea clear of inflammation and nerve damage.
In particular, the growing picture from research suggests that immune cells in the cornea are unusual compared to other immune responses. Trauma in cornea activates a range of different, timed immune responses including bringing in new immune cells that are more closely coordinated to ensure that inflammation is avoided as much as possible.
Dr Lisa Hill, Associate Professor in Ocular disease and Therapeutics at the University of Birmingham said:
“We know that there are new immune cells that enter the cornea after it is damaged. These cells are typically newly recruited in all tissues after trauma and damage, but in the cornea cells that normally live in the tissue likely contribute to the early process of nerve recovery and decorin treatment enhances these neuroprotective behaviours”.
Co-lead author Associate Professor Laura Downie from the University of Melbourne said:
“The cornea recruits more dendritic cells during the early phase of the wound healing process. Notably, at later stages after corneal injury, our novel therapeutic – decorin – dampens the recruitment of other immune cells that typically cause tissue damage.”
Dr Holly Chinnery, Senior Lecturer in Optometry and Vision Sciences at the University of Melbourne and lead author of the study said:
“Over the past 20 years, there has been a large shift in the understanding of corneal immune cells. Initially these cells were considered absent from the centre of the cornea, and they were mostly considered as cells that bridged the innate and adaptive immune system. Studies have more recently proposed that their close association with sensory nerves reflects their important functions in tissue homeostasis and nerve regeneration after injury. In particular, dendritic cells in the epithelium, in the presence of topically applied decorin, may shape the inflammatory response that follows after sterile trauma.
“This makes these cells, which are present in normal healthy human corneas, an attractive target to improve nerve regeneration after injury, which is a common consequence after refractive surgery and other ocular surgical procedures. Going forward, therapeutic strategies could consider combining the power of the resident immune cells, together with novel topical treatments such as decorin, to treat sensory nerve repair in injured corneas.”