Cellular Contractility Profiles of Human Diabetic Corneal Stromal Cells

Diabetic keratopathy is a corneal complication of diabetes mellitus (DM). Patients with diabetic keratopathy are prone to developing corneal haze, scarring, recurrent erosions, and significant wound healing defects/delays. The purpose of this study was to determine the contractility profiles in the diabetic human corneal stromal cells and characterize their molecular signatures. Primary human corneal fibroblasts from healthy, Type 1 DM (T1DM), and Type 2 DM (T2DM) donors were cultured using an established 3D collagen gel model. We tracked, measured, and quantified the contractile footprint over 9 days and quantified the modulation of specific corneal/diabetes markers in the conditional media and cell lysates using western blot analysis. Human corneal fibroblasts (HCFs) exhibited delayed and decreased contractility compared to that from T1DMs and T2DMs. Compared to HCFs, T2DMs demonstrated an initial downregulation of collagen I (day 3), followed by a significant upregulation by day 9. Collagen V was significantly upregulated in both T1DMs and T2DMs based on basal secretion, when compared to HCFs. Cell lysates were upregulated in the myofibroblast-associated marker, α-smooth muscle actin, in T2DMs on day 9, corresponding to the significant increase in contractility rate observed at the same time point. Furthermore, our data demonstrated a significant upregulation in IGF-1 expression in T2DMs, when compared to HCFs and T1DMs, at day 9. T1DMs demonstrated significant downregulation of IGF-1 expression, when compared to HCFs. Overall, both T1DMs and T2DMs exhibited increased contractility associated with fibrotic phenotypes. These findings, and future studies, may contribute to better understanding of the pathobiology of diabetic keratopathy and ultimately the development of new therapeutic approaches.

Role of nicergoline in corneal wound healing in diabetic rats

Background To investigate the effect of nicergoline on the rate of complete corneal ulcer reepithelialization (CCUR) in diabetic rats with diabetic keratopathy. Methods Forty-eight streptozotocin-induced diabetic rats were randomly divided into two groups. The experimental group (n = 24) received nicergoline (10 mg.kg− 1.day− 1), while the control group (n = 24) received a placebo. A corneal epithelial defect was induced using a corneal diamond burr, and defect area was compared at time points of 0, 12, 24, 48 and 72 h after the injury using image analysis software. The probability of CCUR within 72 h was assessed using the Kaplan–Meier survival analysis log-rank test. Results When compared, 4 of the 24 rats (17%) in the placebo group and 12 of the 24 rats (50%) in the nicergoline group were found to have CCUR within 72 h (log-rank = 0.027). Cox regression analysis found no effect of the covariates blood glucose (P = 0.601) or weight (P = 0.322) on the corneal reepithelialization (survival) curve. Conclusions Nicergoline increased wound healing rates relative to placebo and may therefore be investigated as a treatment option in diabetic keratopathy.

Role of Nicergoline in Corneal Wound Healing in Diabetic Rats

Background: To investigate the effect of nicergoline on the rate of complete corneal ulcer reepithelialization (CCUR) in diabetic rats with diabetic keratopathy.Methods: Forty-eight streptozotocin-induced diabetic rats were randomly divided into two groups. The experimental group (n=24) received nicergoline (10 mg.kg-1.day-1), while the control group (n=24) received a placebo. A corneal epithelial defect was induced using a corneal diamond burr, and defect area was compared at timepoints of 0, 12, 24, 48 and 72 hours after the injury using image analysis software. The probability of CCUR within 72 hours was assessed using the Kaplan–Meier survival analysis log-rank test. Results: When compared, 4 of the 24 rats (17%) in the placebo group and 12 of the 24 rats (50%) in the nicergoline group were found to have CCUR within 72 hours (log-rank = 0.027). Cox regression analysis found no effect of the covariates blood glucose (P=0.601) or weight (P=0.322) on the corneal reepithelialization (survival) curve. Conclusions: Nicergoline increased wound healing rates relative to placebo and may therefore be investigated as a treatment option in diabetic keratopathy.

Role of VIP and Sonic Hedgehog signaling pathways in mediating epithelial wound healing, sensory nerve regeneration and their defects in diabetic corneas

Diabetic Keratopathy, a sight-threatening corneal disease, comprises several symptomatic conditions including delayed epithelial wound healing, recurrent erosions, and sensory nerve (SN) neuropathy. We investigated the role of neuropeptides in mediating corneal wound healing, including epithelial wound closure and SN regeneration. Denervation by Resiniferatoxin severely impaired corneal wound healing and markedly up-regulated pro-inflammatory gene expression. Exogenous neuropeptides CGRP, SP, and VIP partially reversed Resiniferatoxin’s effects, with VIP specifically inducing IL-10 expression. Hence, we focused on VIP and observed that wounding induced VIP and VIPR1 expression in normal (NL), but not diabetic (DM) mouse corneas. Targeting VIPR1 in <em>NL</em> corneas attenuated corneal wound healing, dampened wound-induced expression of neurotrophic factors, and exacerbated inflammatory responses while exogenous VIP had the opposite effects in DM corneas. Remarkably, wounding and diabetes also affected the expression of Sonic Hedgehog (SHH) in a VIP-dependent manner. Downregulating SHH expression in NL corneas decreased, while exogenous SHH in DM corneas increased the rates of corneal wound healing. Furthermore, inhibition of SHH signaling dampened VIP-promoted corneal wound healing. We conclude that VIP regulates epithelial wound he<a></a><a>aling, inflammatory response, and nerve regeneration in the corneas in a</a> SHH-dependent manner, suggesting a therapeutic potential for these molecules in treating diabetic keratopathy.

Role of VIP and Sonic Hedgehog signaling pathways in mediating epithelial wound healing, sensory nerve regeneration and their defects in diabetic corneas

Diabetic Keratopathy, a sight-threatening corneal disease, comprises several symptomatic conditions including delayed epithelial wound healing, recurrent erosions, and sensory nerve (SN) neuropathy. We investigated the role of neuropeptides in mediating corneal wound healing, including epithelial wound closure and SN regeneration. Denervation by Resiniferatoxin severely impaired corneal wound healing and markedly up-regulated pro-inflammatory gene expression. Exogenous neuropeptides CGRP, SP, and VIP partially reversed Resiniferatoxin’s effects, with VIP specifically inducing IL-10 expression. Hence, we focused on VIP and observed that wounding induced VIP and VIPR1 expression in normal (NL), but not diabetic (DM) mouse corneas. Targeting VIPR1 in <em>NL</em> corneas attenuated corneal wound healing, dampened wound-induced expression of neurotrophic factors, and exacerbated inflammatory responses while exogenous VIP had the opposite effects in DM corneas. Remarkably, wounding and diabetes also affected the expression of Sonic Hedgehog (SHH) in a VIP-dependent manner. Downregulating SHH expression in NL corneas decreased, while exogenous SHH in DM corneas increased the rates of corneal wound healing. Furthermore, inhibition of SHH signaling dampened VIP-promoted corneal wound healing. We conclude that VIP regulates epithelial wound he<a></a><a>aling, inflammatory response, and nerve regeneration in the corneas in a</a> SHH-dependent manner, suggesting a therapeutic potential for these molecules in treating diabetic keratopathy.