Dry eye evaluation in an ocular GVHD murine model

Abstract

Purpose: Dry eye is a disease that results in tear film instability with potential damage to the ocular surface and is accompanied by an increased osmolarity of the tear film. One of the possible causes of dry eye is inflammation, as occurs in patients with graft versus host disease (GVHD). The purpose of the present study was to develop a new model of murine dry eye, secondary to GVHD, to be used for better characterization of the immune pathogeny of dry eye and for the subsequent testing of new therapeutic strategies.

Methods: Bone marrow and spleen were harvested from male C57BL/6 mice. Female BALB/c mice were the recipients in the GVHD model. Non transplanted female BALB/c mice were used as control. Recipient mice received total body irradiation from a Cs source. Irradiation was followed by the infusion of 5x10⁶ allogeneic donor BM cells intravenously together with splenocytes (5x10⁶ cells) as a source of allogeneic T cells. Mice were monitored twice a week. Ocular affectation was evaluated according to three clinical features: loss of periocular fur, crusting of the eyelid margin/erythematous lids and, blepharospasm. Tear film osmolarity was measured using TearLab Osmolarity System. Basal tear production was measured with the phenol red thread test (PRT). Mice were euthanized one month after allogeneic transplant. Then, both corneas were extracted, fixed and processed for histological analysis.

Results: Each eye was scored between 0-2 depending on the grade of ocular GVHD manifestations. All mice showed signs of ocular affectation 30 days after transplant, while the moment of its appearance was variable. These signs began around 7-10 days post-transplant. Tear osmolarity in GVHD affected mice with no ocular manifestations (331,7±5,67mOsm/L) was significantly higher than the observed in 1 valued GVHD mice (363,5 ± 10,63 mOsm/L; P <0,05) and 2 valued GVHD mice (375,9±9,19mOsm/L; P<0,001). No differences were observed between the control group and mice developing GVHD scored 0 and 1 ; however significant differences were observed when compared with 2 valued GVHD mice. PRT test indicated differences between GVHD affected eyes and healthy eyes. Histological analysis of the corneas demonstrated significant differences between control and GVHD mice in terms of epithelium thickness and number of cell layers.

Conclusions: These data support the use of our GVHD murine model of to characterize the immune pathogeny of dry eye syndrome.