Abstract
Purpose :
We previously reported that Spontaneously Diabetic Torii (SDT) rats, an animal model of type 2 diabetes mellitus without obesity, showed delayed corneal wound healing and subclinical inflammation histologically. This study tested the hypothesis that SDT and SDT fatty model rats also develop corneal inflammation using the cornea suture inflammation model.
Methods :
Ten male SDT rats and 10 male SDT fatty rats over 43 weeks of age were used for experiment. Ten male Sparague-Dawley (SD) rats were used as control. Three 10-0 nylon sutures were placed in the para-central corneal stroma under deep general anesthesia. One week after suture placement, we checked corneal opacity and neovascularization by surgical microscope, and sacrificed animals for histological study. HE staining and expression of CD4, CD8, MMP9 and F4/80 were examined immunohistologically. We compared the number of positive staining cells per 1 mm2 in the central corneal, sutured area, and peripheral corneal area. Kruskal-Wallis test was used for statistical analysis.
Results :
Corneal opacity was not different in 3 groups. Corneal neovasculization staging (classified 0-4) was 2.0±0.43 in SDT, 2.7±0.52 in SDT fatty, and 2.0±0.43 in the SD group, and was found to the statistically higher in the SDT fatty group (p=0.04). HE staining showed a large number of infiltrating cells near the suture in all 3 groups. CD4 positive cells were observed only in sutured area of SDT fatty group. CD8 positive cells were observed in sutured and peripheral area of all groups, especially in the peripheral area of SDT group (p=0.04). Many MMP9 and F4/80 positive cells were observed in all areas of all groups. In particular, MMP9 positive cells were observed in the peripheral area of SDT group (p=0.004), and F4/80 positive cells were observed in the central area of SDT fatty group (p=0.04).
Conclusions :
In a corneal inflammation model of diabetic rats, angiogenesis was enhanced with more inflammatory cell infiltration. Onset and degree of inflammation may be stronger in the diabetic cornea.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.