Journal of Eye & Cataract Surgery Open Access

Introduction

"This is really the firstdemonstration that surveillance byimmune cells of the lens in response to injury somewhere else inthe eye," Dr. Menko says. The researchers also found that someimmune cells were able to cross the lens capsule, a membranousstructure that helps to keep the lens under tension. The resultscould point to a role for immune cells in cataract formation.Together, the findings indicate that in response to damage ordisease, the eye utilizesalternative mechanisms - rather thandirect contact with the bloodstream like non-transparent tissuesdo - to ensure that immune cells get to sites to provide healingand protection. "We're excited to go from thinking this doesn'tmake sense to proving that the body is amazing and can adaptto anything. You just have to go in and look for it," Dr. Menkosays. "We should be willing to challenge dogma because that'swhere discovery is," she adds. "It can enlighten what we know ifwe always keep our mind open to what doesn't make sense andwhat maybe should be challenged to understand things better.The lens of the eye is an unusual organ.

Unlike most of thebody's organs, blood vessels don't reach the lens. If they did,they'd obscure our vision and we wouldn't be able to see. Thelack of vasculature led scientists to believe immune cells, whichtravel via the bloodstream, couldn't get to this part of the bodyeither. But a few years ago, Jefferson researchers challenged thislong held assumption by demonstrating that immune cellspopulate the lens in response to degeneration. Now theJefferson team finds the eye also launches an immune responsein the lens after injury. The discovery adds to a growing body ofevidence that is working to overturn the accepted dogma of thefield. "Why would we evolve a tissue that is so central to ourbeing able to see without ways to ensure its protection, itsability to repair itself?" says, Sue Menko, PhD, Professor in theDepartment of Pathology, Anatomy and Cell Biology at ThomasJefferson University, who led the research. "Immune cells arecentral to that protection and repair." The lens of the eye workslike a camera lens. Its main purpose is to focus images coming inthrough the cornea - the transparent front layer of the eye -onto the retina at the back of the eye. The images are detectedby the retina and then translated in the brain as what we see.That lens must be crystal clear. As a result, scientists have alwaysdescribed the lens as a tissue without vasculature and thereforeno source of immune cells either. The puzzle led Dr. Menko andher team to investigate whether immune cells are present in theeye. In a previous study, they discovered that when the lens is ina diseased state, immune cells are not only recruited there, butthey also show up in the cornea, retina, and vitreous body - allparts of the eye that don't normally have immune cells. Dr.Menko's work suggested that the immune cells come from theciliary body, a sort of muscle that helps squeeze and pull thelens, changing its shape, and helping it focus. Now, in the latestwork, Dr. Menko and colleagues show that after injury to thecornea, immune cells travel from the ciliary body to the lensalong fibers known as ciliaryzonules. The researchers usedfluorescent markers and high-powered microscopes to observestructures of mouse eyes one day after receiving a scratch onthe cornea. The high-tech imaging analysis Dr. Menko's teamused revealed that following injury to the cornea, the immunesystem launches a response to protect the lens. Immune cellsare recruited to the lens via the ciliaryzonules, and crawl alongthe surface of the lens to surveille and protect from adverseimpacts of the corneal wound.