Nerve influence on the metabolism of type I and type II diabetic corneal stroma: an in vitro study

Corneal innervation plays a major role in the pathobiology of diabetic corneal disease. However, innervation impact has mainly been investigated in the context of diabetic epitheliopathy and wound healing. Further studies are warranted in the corneal stroma-nerve interactions. This study unravels the nerve influence on corneal stroma metabolism. Corneal stromal cells were isolated from healthy (HCFs) and diabetes mellitus (Type1DM and Type2 DM) donors. Cells were cultured on polycarbonate membranes, stimulated by stable Vitamin C, and stroma-only and stroma-nerve co-cultures were investigated for metabolic alterations. Innervated compared to stroma-only constructs exhibited significant alterations in pyrimidine, glycerol phosphate shuttle, electron transport chain and glycolysis. The most highly altered metabolites between healthy and T1DMs innervated were phosphatidylethanolamine biosynthesis, and pyrimidine, methionine, aspartate metabolism. Healthy and T2DMs main pathways included aspartate, glycerol phosphate shuttle, electron transport chain, and gluconeogenesis. The metabolic impact on T1DMs and T2DMs was pyrimidine, purine, aspartate, and methionine. Interestingly, the glucose-6-phosphate and oxaloacetate was higher in T2DMs compared to T1DMs. Our in vitro co-culture model allows the examination of key metabolic pathways corresponding to corneal innervation in the diabetic stroma. These novel findings can pave the way for future studies to fully understand the metabolic distinctions in the diabetic cornea.

Altered Corneal Innervation and Ocular Surface Homeostasis in FHV-1-Exposed Cats: A Preliminary Study Suggesting Metaherpetic Disease

Metaherpetic disease is recognized in humans affected by herpes simplex virus-1 but is not reported in cats affected by feline herpesvirus-1 (FHV-1) despite the high prevalence of herpetic disease in this species and strong similarities in viral biology between alphaherpesviruses of humans and cats. This preliminary work evaluated cats naïve to FHV-1 (n = 9 cats, 18 eyes; control population) and cats naturally exposed to FHV-1 (n = 4 cats, 7 eyes), as confirmed by serologic testing and review of medical records. Antemortem assessment included clinical scoring, blink rate, corneal aesthesiometry, tear film breakup time (TFBUT), and Schirmer tear test-1 (STT-1) with or without the nasolacrimal reflex. Post-mortem assessment involved confocal microscopy of the corneas and evaluation of corneal nerves with ImageJ. Groups were compared with Student's t-tests and results are presented as mean ± standard deviation. Compared to control, herpetic cats had significantly higher (P ≤ 0.010) clinical scores (0.2 ± 0.4 vs. 4.6 ± 2.8) and response to nasolacrimal stimulation (7.8 ± 10.8% vs. 104.8 ± 151.1%), significantly lower (P < 0.001) corneal sensitivity (2.9 ± 0.6 cm vs. 1.4 ± 0.9 cm), STT-1 (20.8 ± 2.6 mm/min vs. 10.6 ± 6.0 mm/min), TFBUT (12.1 ± 2.0 s vs. 7.1 ± 2.9 s), and non-significantly lower blink rate (3.0 ± 1.5 blinks/min vs. 2.7 ± 0.5 blinks/min; P = 0.751). All parameters evaluated for corneal nerves (e.g., nerve fiber length, branching, occupancy) were notably but not significantly lower in herpetic vs. control cats (P ≥ 0.268). In sum, cats exposed to FHV-1 had signs suggestive of corneal hypoesthesia and quantitative/qualitative tear film deficiencies when compared to cats naïve to the virus. It is possible these are signs of metaherpetic disease as reported in other species.

Dorsolateral medullary infarction registry: a study protocol for a prospective, multicentric registry

Background Dorsolateral medullary infarction is a typical cerebral infarction which is characterized by Wallenberg’s syndrome. Neurotrophic keratopathy is an uncommon consequence of dorsolateral medullary infarction. At present, the protocol is aimed to study the dynamic changes in corneal innervation and the ocular surface environment after dorsolateral medullary infarction. Methods This study will involve consecutive data from all medical records of patients within 7 days of acute dorsolateral medullary infarction onset at the Departments of Neurology from 10 collaborating stroke centers. Eligible patients will mainly be characterized based on detailed physical examinations, multimodal imaging, and corneal related examinations and patients will be followed-up for 2 years. Neurotrophic keratopathy after dorsolateral medullary infarction is the primary endpoint. The dynamic histological corneal innervation and ocular surface environment after dorsolateral medullary infarction will be observed during the follow-up period. Discussion This multicentric, prospective registry is the first to identify and characterize the dynamic changes of corneal innervation and the ocular surface environment after acute dorsolateral medullary infarction. The significance of the study is to emphasize that the curative effect is based on the doctors’ identification of the disease in the earliest stage before irreversible damage occurs to the cornea. Trial registration The registry was registered (ChiCTR-OPC-17,011,625) on June 11, 2017.

Effectiveness of Treatment of Bacterial Keratitis in Diabetes Patients Depending on the Severity of Diabetic Polyneuropathy

The aim of the study was to identify the features of bacterial keratitis in patients with diabetes mellitus, depending on the severity of diabetic polyneuropathy in complex treatment with eye drops which contain alpha-lipoic acid, citicoline, cyanocobalamine and hyaluronic acid. Materials and methods. 15 patients with type 1 diabetes mellitus and bacterial keratitis were observed. Ophthalmological examination except of standard methods, included bacteriological examination, fluorescein test, noncontact corneal esthesiometry. All patients were treated with instillations of the antibiotic ofloxacin, standard anti-inflammatory therapy, and instillations of eye drops Tioretin A and OMK 2 twice a day locally. Observations were made on the first, third, seventh, tenth, fourteenth, eighteenth and twenty-second days. Results and discussion. In all periods of observation, the severity of conjunctival hyperemia and corneal edema, as well as the size of corneal erosion at the stage of severe complications diabetic polyneuropathy exceeded the corresponding rates of patients with asymptomatic and symptomatic degree. Normalization of conjunctiva color, reepithelialization of the cornea and disappearance of corneal opacification in all patients with severe complications diabetic polyneuropathy occurred 4 days later than in patients with asymptomatic and symptomatic degree. Conclusions. The course of bacterial keratitis depends on the severity of diabetic polyneuropathy: more pronounced violation of corneal innervation is marked at the stage of severe complications diabetic polyneuropathy, which manifested by decrease in its sensitivity, and led to the prolongation of the disease.

PECULIARITIES OF BACTERIAL KERATITIS IN PATIENTS WITH DIABETES MELLITUS DEPENDING ON THE SEVERETY OF DIABETIC POLINEUROPATHY

Summery. The dependence of the peculiarities of bacterial keratitis on the severity of DPN was proven with the help of 15 patients with type 1 diabetes mellitus. During all periods of observation, the severity of conjunctival hyperemia, the size of erosion and the threshold of corneal sensitivity at the stage of severe complications exceeded the corresponding indicators of patients with asymptomatic DPN. Normalization of conjunctival color in all patients with severe complications occurred at 8 days, and reepithelialization of the cornea 4 days later than in asymptomatic DPN. On the last 22nd day of observation, the corneal opacification of the peripheral localization remained in 33.3% of patients (2 patients) with the stage of severe complications, whereas in all patients with asymptomatic DPN the cornea was already transparent on the 14th day of observation. The threshold of corneal sensitivity at 22nd day in patients with severe complications was 35.3% higher than with asymptomatic DPN (p <0.05). So, patients with severe complications DPN with bacterial keratitis show a more pronounced violation of corneal innervation, which manifests by decrease of its sensitivity, and leads to prolongation of the duration of the disease.