Insulin analogues may accelerate progression of diabetic retinopathy after impairment of inner blood-retinal barrier

Incidence, progression and regression of diabetic retinopathy in a northeastern Chinese population

AIM

To determine the incidence, progression and regression of diabetic retinopathy (DR), with corresponding risk factors, in a northeastern Chinese population of patients with type 2 diabetes.

METHODS

Among 2006 patients who completed baseline examinations in 2012-2013 and underwent re-examination after a mean interval of 21.2 months, 1392 patients with gradable fundus photographs for both baseline and follow-up examinations were included. Incidence was defined as new development of any DR among patients without DR at baseline. An increase of ≥2 scales (concatenating Early Treatment Diabetic Retinopathy Study levels of both eyes) in eyes with DR at baseline was defined as progression, while a reduction of ≥2 scales was defined as regression.

RESULTS

The age- and sex-standardised incidence, progression and regression were 5.8% (95% CI 4.7% to 6.9%), 26.8% (95% CI 24.8% to 28.8%) and 10.0% (95% CI 8.6% to 11.3%), respectively. In addition to poor blood glucose control, wider central retinal venular equivalent was associated with both incidence (relative risk (RR) 2.17, 95% CI 1.09 to 4.32, for ≥250 µm vs <210 µm) and progression (RR 2.00, 95% CI 1.02 to 3.96, for ≥250 µm vs <210 µm). Patients without insulin therapy (RR 0.64, 95% CI 0.43 to 0.97) and patients with wider central retinal arteriolar equivalent (RR 1.14, 95% CI 1.02 to 1.26, per 10 µm increase) were likely to exhibit DR regression.

CONCLUSION

We determined the incidence, progression and regression of DR among northeastern Chinese patients with type 2 diabetes. Retinal vessel diameters, in addition to blood glucose level, influence the natural evolution of DR.

Neuroprotective effect of He-Ying-Qing-Re formula on retinal ganglion cell in diabetic retinopathy

ETHNOPHARMACOLOGY RELEVANCE

He-Ying-Qing-Re Formula (HF) was empirically modified from Si-Miao-Yong-An Decoction (SD), which was recorded in the literature of Divine Doctor's Secret Transmission, and has been utilized for centuries to treat vasculopathy through clearing heat and accelerating bloodstream. HF has been used as an effective holistic treatment of diabetic retinopathy (DR) for decades and experimentally reported to ameliorate retinal condition in diabetic mice.

AIM OF THE STUDY

Our study aims to investigate the effect of HF in preventing sustained hyperglycemia and hyperlipidemia-associated retinal ganglion cell (RGC) cell death and its possible mechanism.

MATERIALS AND METHODS

Chromatographic fingerprint of HF was obtained upon the UPLC-based analytic system; Diabetic retinopathy was established in streptozotocin (STZ) injection-induced hyperglycemic mice; Alterations of retinal structure was assayed by H&E staining. Expression of PSD-95 and CHOP in retinae was assessed by immunofluorescence; RGC cell line (mRGC) was used for in vitro study. Cell death was analyzed by flow cytometry; Intracellular reactive oxygen species (ROS) was measured by 2',7'-dichlorofluorescin diacetate (DCFDA); Apoptosis-related proteins and signaling were monitored with immunoblotting and colorimetric assay.

RESULTS

Chlorogenic acid, ferulic acid, and rutin were identified in HF. HF attenuates the loss of RGCs, thinning of inner retinal layers in diabetic mice. Furthermore, expressions of Brn3a and PSD-95 were restored while CHOP level was downregulated upon HF treatment. In vitro study, HF alleviates H₂O₂-induced apoptosis of mRGCs and loss of postsynaptic protein via scavenging ROS and suppressing ATF4/CHOP-mediated endoplasmic reticulum stress and mitochondria-related pro-apoptotic factors, probably as cleaved-caspase-3, and phospho-p38 mitogen-activated protein kinase (MARK). Meanwhile, both pro-survival protein levels like Bcl-2/Bcl-xL and postsynaptic protein of PSD-95 were upregulated upon HF treatment.

CONCLUSION

HF administration was a valid therapeutic approach for DR treatment, oriented at the blockade of endoplasmic reticulum- and mitochondria-dependent oxidative stress-induced retinal neurodegeneration including RGC apoptosis.

Oxidative stress impact on growth hormone secretion in the eye

Aim

To evaluate the influence of oxidative stress on extrapituitary growth hormone (GH) secretion in the eye and to analyze the interdependence between eye and serum GH levels under normal and hypoxic conditions.

Methods

Pars plana vitrectomy (PPV) was performed in 32 patients with developed proliferative diabetic retinopathy (PDR) and 49 non-diabetic controls, both of whom required this procedure as part of their regular treatment in the period from April 2013 to December 2014. During PPV, vitreous samples were taken and blood was simultaneously collected from the cubital vein. GH levels in serum and vitreous samples were measured by electrochemical luminescence assay. Oxidative stress was measured by enzyme-linked immunosorbent assay of advanced oxidation protein products (AOPP) and lipid hydroperoxide (LPO) in serum and vitreous.

Results

Serum AOPP levels were significantly higher than vitreous levels in both groups (P < 0.001 for each group) and LPO levels were significantly higher only in PDR group (P < 0.001). There was a significant positive correlation between serum and vitreous LPO levels in PDR group (r = 0.909; P < 0.001). Serum GH levels were significantly higher than vitreous levels in both groups (P < 0.001 for each group). Serum GH levels were significantly higher in PDR group than in controls (P = 0.012). Vitreous GH values were slightly higher in PDR group, but the difference was not significant.

Conclusion

Our study confirms that GH production in the eye is autonomous and independent of oxidative stress or pituitary GH influence.

Effect of the blockade of the IL-23-Th17-IL-17A pathway on streptozotocin-induced diabetic retinopathy in rats

PURPOSE

T helper 17 (Th17) cells are believed to play a critical role in the chronic inflammatory and immune response in streptozotocin (STZ)-induced retinopathy. The purpose of our study was to investigate the effect of the IL-23-Th17-IL-17A pathway via the blood-retinal barrier on STZ-induced diabetic retinopathy in rats.

METHODS

The ratio of IL-17A(+)CD4(+) T cells in peripheral blood mononuclear cells of STZ-treated and wild-type rats was determined using flow cytometry. The IL-17A mRNA levels in the retinas were measured using real-time PCR. The protein expression of IL-17A in the peripheral blood and retinas was measured using an ELISA kit. The retinal structure in the wild-type and STZ-treated rats was examined using hematoxylin and eosin (H&E) staining. Additionally, the permeability of the blood-retinal barrier was quantified using the Evans blue technique.

RESULTS

The ratio of IL-17A(+)CD4(+) T cells in peripheral blood mononuclear cells was markedly increased in rats treated with STZ compared to the wild-type group. IL-17A protein levels in the peripheral blood and retinas were also significantly elevated in STZ-treated rats. However, when the anti-IL 23Rp19 antibody was injected into the vitreous cavity in the eyes of STZ-treated rats for a period of one week, retinal pigment epithelium cells became markedly tighter, and micrangium and endothelial cells were significantly reduced. The expression of IL-17A mRNA and protein in the retina also decreased significantly compared with the placebo-treated group.

CONCLUSIONS

This study provided further insight into the function of the IL-23-Th17-IL-17A pathway in STZ-induced diabetic retinopathy in rats. Local injection of the anti-IL-23Rp19 antibody may improve the structure of the blood-retinal barrier, thus offering the potential for treatment using intravitreal anti-IL-23Rp19 antibodies.