Ocular inflammation in uveal tract in aged obese type 2 diabetic rats (Spontaneously Diabetic Torii fatty rats)

Diabetes, Diabetic Retinopathy, and Inflammatory Disorders

This review summarizes the impact of systemic and ocular inflammatory disorders on diabetes mellitus (DM) and diabetic retinopathy (DR). Local inflammation is a key pathology in diabetic retinopathy (DR) and is also an evolving target for clinical therapy. The legacy effects of local inflammation at the intracellular level make DR a persistent self-driven vicious process. Ocular inflammation is accompanied as well as incited by systemic inflammation due to diabetes mellitus (DM) itself. Over the years, a multitude of studies have evaluated the impact of systemic inflammatory disorders (SIDs, like rheumatoid arthritis, lupus, psoriasis, etc.) and anti-inflammatory drugs prescribed for managing them on manifestations of DM. Recent studies have indicated increased insulin resistance to be a result of chronic inflammation, and the anti-inflammatory drugs to have a protective effect towards DM. Very few studies have evaluated the impact of SIDs on DR. Furthermore, the evidence from these studies is conflicting, and while local anti-inflammatory therapy has shown a lot of clinical potential for use in DR, the results of systemic anti-inflammatory therapies have been inconsistent. The impact of local ocular inflammation due to uveitis on DR is a crucial aspect that has not been evaluated well at present. Initial pre-clinical studies and small-sized clinical reports have shown a strong and positive relationship between the presence of uveitis and the severity of DR as well as its progression, while larger cross-sectional patient surveys have refuted the same. The long term impact of ocular inflammation due to uveitis on DR needs to be studied while adjusting for confounders.

Phosphorylation of αB-Crystallin Involves Interleukin-1β-Mediated Intracellular Retention in Retinal Müller Cells: A New Mechanism Underlying Fibrovascular Membrane Formation

Purpose

Chronic inflammation plays a pivotal role in the pathology of proliferative diabetic retinopathy (PDR), in which biological alterations of retinal glial cells are one of the key elements. The phosphorylation of αB-crystallin/CRYAB modulates its molecular dynamics and chaperone activity, and attenuates αB-crystallin secretion via exosomes. In this study, we investigated the effect of phosphorylated αB-crystallin in retinal Müller cells on diabetic mimicking conditions, including interleukin (IL)-1β stimuli.

Methods

Human retinal Müller cells (MIO-M1) were used to examine gene and protein expressions with real-time quantitative PCR, enzyme linked immunosorbent assay (ELISA), and immunoblot analyses. Cell apoptosis was assessed by Caspase-3/7 assay and TdT-mediated dUTP nick-end labeling staining. Retinal tissues isolated from the Spontaneously Diabetic Torii (SDT) fatty rat, a type 2 diabetic animal model with obesity, and fibrovascular membranes from patients with PDR were examined by double-staining immunofluorescence.

Results

CRYAB mRNA was downregulated in MIO-M1 cells with the addition of 10 ng/mL IL-1β; however, intracellular αB-crystallin protein levels were maintained. The αB-crystallin serine 59 (Ser59) residue was phosphorylated with IL-1β application in MIO-M1 cells. Cell apoptosis in MIO-M1 cells was induced by CRYAB knockdown. Immunoreactivity for Ser59-phosphorylated αB-crystallin and glial fibrillary acidic protein was colocalized in glial cells of SDT fatty rats and fibrovascular membranes.

Conclusions

The Ser59 phosphorylation of αB-crystallin was modulated by IL-1β in Müller cells under diabetic mimicking inflammatory conditions, suggesting that αB-crystallin contributes to the pathogenesis of PDR through an anti-apoptotic effect.

Clinical features of patients with diabetic anterior uveitis

AIM

To describe clinical features and outcomes of new-onset anterior uveitis associated with poorly controlled or undiagnosed diabetes mellitus.

METHODS

Retrospective analysis of 25 eyes of 18 patients (14 men, 4 women; mean age 44 years) who presented between December 2001 and October 2016 to the Kyorin Eye Center.

RESULTS

Ocular findings at presentation included posterior synechiae (15 eyes, 60%), anterior chamber fibrin (13 eyes, 52%), keratic precipitates (10 eyes, 40%), Descemet membrane folds (7 eyes, 28%) and hypopyon (3 eyes, 12%). Seven cases were bilateral. Intraocular pressure >21 mm Hg (7 eyes, 28%) and diabetic retinopathy (7 eyes, 28%, all non-proliferative) were also noted. The mean random blood glucose was 332 mg/dL (range 135-604 mg/dL) and the mean haemoglobin A1c was 12.6% (range 9.7%-16.7%). Seven patients (39%) were unaware of their hyperglycaemic state, and the remainder had either poor glucose control or had discontinued their diabetes treatment. Systemic examination and ancillary testing ruled out other possible causes of the uveitis. The ocular inflammation was managed in all cases using local corticosteroid therapy (drops and subconjunctival injections) in addition to internal medicine intervention for the diabetes. The best-corrected visual acuity (BCVA) was improved or maintained in all eyes at 3 months. The BCVA was ≤0.5 in two eyes due to both cataract and diabetic macular oedema.

CONCLUSIONS

We characterised new-onset anterior uveitis in 18 patients in association with poorly controlled or undiagnosed diabetes mellitus. The uveitis was managed in all cases with local corticosteroid therapy in addition to proper diabetes systemic treatment.

Diabetic macular edema-like ocular lesions in male spontaneously diabetic torii fatty rats

Diabetic macular edema (DME) is a major factor contributing to visual disabilities in diabetic patients, and the number of patients is increasing. Animal models play a key role in the development of novel therapies. In this study, pathophysiological analyses of ocular lesions in Spontaneously Diabetic Torii (SDT) fatty rats were performed. First, vascular endothelial growth factor (VEGF) concentrations in vitreous humor, retinal vascular permeability and retinal thickness were measured in SDT fatty rats (Experiment 1). Furthermore, the pharmacological effects of two anti-diabetic drugs, phlorizin and pioglitazone, on retinal lesions were evaluated (Experiment 2). As results, the SDT fatty rats exhibited VEGF increase in vitreous humor at 8 and 16 weeks of age, and both retinal vascular hyperpermeability and retinal thickening at 16 weeks of age. In particular, the layers between the retinal internal limiting membrane and the outer nuclear layer were thickened. Phlorizin treatment from 4 to 16 weeks of age improved hyperglycemia and normalized retinal thickness; however, the effect of pioglitazone on retinal thickness was not strong despite the normalization of hyperglycemia. These data demonstrate that the male SDT fatty rat is a useful model for developing new therapeutic approaches in DME.