Abstract
Purpose :
Our previous studies provided the first evidence that despite the fact that the lens is avascular, it contains a subpopulation of tissue resident immune cells, a typical feature of most other tissues. As the properties of resident immune cells can include many tissue-protective functions, our purpose is to provide a deeper understanding of the properties specific of this unique lens cell population in order to begin to elucidate how they function in the lens.
Methods :
This study uses both human and chick embryo post-cataract surgery injury explant cultures. Properties of resident immune cells associated with the lens epithelium on their endogenous basement membrane capsule and after these cells migrate of the capsule and onto the rigid tissue culture plastic surrounding the explant are examined by confocal microscopy imaging following immunofluorescence labeling.
Results :
Resident immune cells that we have previously shown populate the lens during development were found to travel to the lens along the ciliary zonules in the absence of a vasculature. These cells were identified based on their expression of a monocyte/macrophage molecule. In the human post-cataract surgery explants CD45+ immune cells interspersed among the cells of the lens epithelium often extend dendritic processes consistent with the morphology of antigen presenting cells. These CD45+ cells migrate to the wound edge of the explant, where the transmembrane glycoprotein CD44, a hyaluronic acid receptor expressed by immune cells, is induced. With the chick post-cataract surgery explants we show that the CD44+ resident immune cells activated to migrate to the wound edge are vimentin-rich cells that express the TLR4 co-receptor CD14, identifying them as monocytes/macrophages and/or dendritic cells. Within 6 days after placing the human post-cataract surgery explants in culture, the CD45+ immune cells present remaining associated with the basement membrane capsule among the lens epithelial cells and those that had migrated onto the rigid substrate surrounding the explant, have acquired a myofibroblast phenotype.
Conclusions :
Resident immune cells of the lens function as immediate responders to injury with properties consistent with their function as the liaisons between the innate and adaptive immune response and with the potential to acquire a myofibroblast phenotype, the agents of fibrosis.
This is a 2021 ARVO Annual Meeting abstract.