Effects of Topical 1,25 and 24,25 Vitamin D on Diabetic, Vitamin D Deficient and Vitamin D Receptor Knockout Mouse Corneal Wound Healing

Abstract

Delayed or prolonged corneal wound healing and non-healing corneas put patients at risk for ocular surface infections and subsequent stromal opacification, resulting in discomfort or visual loss. It is important to enhance corneal wound healing efficiency and quality. Vitamin D (Vit D) is both a hormone and a vitamin, and its insufficiency has been linked to immune disorders and diabetes. For this study, wound healing and recruitment of CD45+ cells into the wound area of normoglycemic and diabetic mice were examined following corneal epithelial debridement and treatment with 1,25-dihyroxyvitamin D (1,25 Vit D) or 24,25-dihydroxyvitamin D (24,25 Vit D). Treatment with topical 1,25-dihyroxyvitamin D (1,25 Vit D) resulted in significantly increased corneal wound healing rates of normoglycemic, diabetic and diabetic Vit D deficient mice. Furthermore, 24,25-dihydroxyvitamin D (24,25 Vit D) significantly increased corneal wound healing of diabetic Vit D deficient and Vit D receptor knockout (VDR KO) mice. In addition, CD45+ cell numbers were reduced in diabetic and VDR KO mouse corneas compared to normoglycemic mice, and 24,25 Vit D increased the recruitment of CD45+ cells to diabetic mouse corneas after epithelial debridement. CD45+ cells were found to infiltrate into the corneal basal epithelial layer after corneal epithelial debridement. Our data indicate that topical Vit D promotes corneal wound healing and further supports previous work that the Vit D corneal wound healing effect is not totally VDR-dependent.

Effects of 1,25-Vitamin D3 and 24,25-Vitamin D3 on Corneal Nerve Regeneration in Diabetic Mice

“…The current study found that CD45+ cells with a dendriform morphology were significantly decreased in the basal epithelial layer of wounded diabetic mouse corneas compared to normoglycemic mice, with topical 24,25 Vit D increasing their numbers. These results are in agreement with an earlier study from our laboratory in which the corneas received only an epithelial abrasion with no stromal damage, and cells were counted at the level of the highest cell density, as opposed to the basal epithelium, where corneal nerves terminate [19]. Pertinant to the current study, it has been shown that CD45+ cells and macrophages play a pivotal role in the mechanisms involved in peripheral nerve regeneration and degeneration [56].…”

“…CD45+ cells and macrophages in the basal epithelium were immunostained after the corneas were wounded as described above and treated with 1,25 Vit D or 24,25 Vit D three times over 8 h. CD45 and F4/80 antibodies were used to immunolabel hematopoieticderived immune cells and macrophages, respectively [19,39,40]. The eyes were fixed with Zamboni fixative (American MasterTech Scientific, Lodi, CA, USA) for 75 min and then washed three times with PBS.…”

“…Resident immune cells distributed throughout the corneal epithelium and stroma include dendritic cells, macrophages, mast cells, and innate lymphoid cells [14,15]. Large numbers of CD45+ cells invade the stroma after mouse cornea epithelial debridement, including monocytes, macrophages, neutrophils, lymphocytes, and stem cells [16][17][18][19]. Stromal macrophages were found to promote nerve remodeling after epithelial abrasion [20] and to contribute to corneal homeostasis and pathology [21].…”

Exploring Skin Wound Healing Models and the Impact of Natural Lipids on the Healing Process

“…Recently, the Zhang laboratory conducted a clinical trial demonstrating the efficacy of topical vitamin D 3 in treating chloasma, a condition of hypermelanosis occurring during pregnancy, as well as in enhancing wound healing outcomes [28]. In another study, the Watsky laboratory found that both topical 1,25(OH) 2 D 3 and 24,25(OH) 2 D 3 accelerate corneal wound healing in mice [29]. Additionally, in a recent review, Bikle emphasized the importance of vitamin D and calcium signaling in epidermal wound healing, highlighting their role in stem cell activation and re-epithelialization [30].…”