Circumlimbal suture provides a simple and cost-effective way to induce mild chronic ocular hypertension in rat eyes. This model produces preferential ganglion cell dysfunction and RNFL reduction.

The present study demonstrated that murine hyalocytes were responsive to aging, hyperglycemia, locally produced VEGF, and both systemic and ocular-derived TLR ligands. Thus hyalocytes or vitreous macrophages may be a valuable and previously unrecognized sensitive indicator of pathologic changes in the eye.

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Monocytes of bone marrow (BM) origin are circulating precursors that replenish dendritic cells and macrophage populations in peripheral tissues during homeostasis. The eye provides a unique range of varying tissue microenvironments in which to compare the different turnover rates of monocyte-derived cells. This was investigated in the present study using radiation chimeras, whereby BM from Cx3cr1(+/gfp) mice was used to rescue myeloablated wild-type (WT) BALB/c mice (conventional chimeras). The use of Cx3cr1(+/gfp) mice as BM donors allowed the clear visualization of newly recruited monocyte-derived cells. Following BM reconstitution, mice were killed at 2, 4, 6, and 8 weeks, and wholemount ocular tissues were processed for immunohistochemistry and confocal microscopy. "Reverse" chimeras (WT into Cx3cr1(+/gfp)) were also created to act as a further method of cross-referencing cell turnover rates. In conventional chimeras, Cx3cr1(+/gfp) cells began repopulating the uveal tract (iris, ciliary body, choroid) 2 weeks post-transplantation with close to complete replenishment by 8 weeks. By contrast, the earliest recruitment of Cx3cr1(+/gfp) cells into the host retina occurred at 4 weeks. In reverse chimeras, a steady accumulation of host Cx3cr1(+/gfp) macrophages in the subretinal space of Cx3cr1(+/gfp) adult mice suggests that these cells arise from long-term resident microglia and not newly recruited WT donor cells. In summary, chimeric mouse models, in which lineage-specific cells carry a fluorescent reporter, have been used in the present study to visualize the turnover of monocyte-derived cells in different tissue compartments of the eye. These data provide valuable insights into differential monocyte turnover rates within a single complex organ.

These data demonstrate that in the first 24 hours after injection of antigen into the anterior chamber of the eye, antigen reaches the lymphoid organs mainly in a soluble form via both the blood and lymph.

These data illustrate that homing or migration of DCs and macrophages to the uveal tract and retina in normal young mice is not Cx3cr1 dependent and provide a solid foundation for future studies of monocyte-derived cells and the role of Cx3cr1 in models of ocular disease.

PURPOSE. Diabetic retinopathy (DR) is a major cause of visual impairment in developed countries. While DR has been described classically as a microvascular disease, recent evidence suggests that changes to retinal microglia are an early feature of retinopathy. In our study, we assessed changes in microglial distribution and morphology in vivo and ex vivo in a mouse model of non-proliferative DR, and further examined effects of age and the absence of the functional chemokine receptor Cx 3 cr1 on the progression of these changes. METHODS.To isolate the effects of the three variables: diabetic status, age, and role of Cx 3 cr1, the Ins2Akita mouse was crossed with Cx 3 cr1-eGFP reporter mice. Eyes were assessed clinically in vivo at 10, 20, 30, and 46 weeks of age, and the retinal structure and arrangement of GFP þ microglia was examined ex vivo using whole mount immunofluorescence staining and confocal microscopy.RESULTS. Clinical examination of the fundus, vasculature, or GFP þ microglial distribution did not reveal any macroscopic changes related to diabetic status: however, ex vivo microscopic analysis revealed alterations in microglial network organization, and evidence of cell shape changes regarded classically as signs of activation, in Ins2Akita mice from 10 weeks of age. These changes were exacerbated in older diabetic mice whose microglia lacked Cx 3 cr1 (Ins2 Akita Cx 3 cr1 gfp/gfp mice). Diabetic status and Cx 3 cr1 deficiency led to accumulations of Iba-1 þ hyalocytes (vitreal macrophages) and subretinal macrophages.CONCLUSIONS. These data showed that changes to murine retinal microglia occur in response to systemic diabetic status in the absence of overt retinopathy and inflammation. These changes are exaggerated in mice lacking Cx 3 cr1, suggesting fractalkineCx 3 cr1 interactions may have a role in early neuronal changes in preproliferative DR. (Invest Ophthalmol Vis Sci.