Association of serum inflammatory markers and diabetic retinopathy: a review of literature

Macular changes following cataract surgery in eyes with early diabetic retinopathy: an OCT and OCT angiography study

Background

To evaluate changes in macular status and choroidal thickness (CT) following phacoemulsification in patients with mild to moderate nonproliferative diabetic retinopathy (NPDR) using optical coherence tomography.

Methods

In this prospective study, all of the patients underwent uncomplicated phacoemulsification. Retinal superficial capillary plexus vascular density (SCP-VD), macular thickness (MT), and CT were measured pre- and postoperatively.

Results

Twenty-two eyes of 22 cataract patients with mild to moderate NPDR without diabetic macular edema (DME) and 22 controls were enrolled. BCVA increased in two groups at 3 months postoperatively. At 1 and 3 months postoperatively, SCP-VD in the diabetic retinopathy (DR) group significantly increased; changes in SCP-VD in parafovea were significantly greater in the DR group than in the control group. MT and CT in the DR group significantly increased at all visits postoperatively in the fovea and perifovea. Changes in parafoveal MT were significantly greater in the DR group than in the control group at all visits postoperatively. Changes in CT and MT in the fovea were significantly greater in patients with DR than in the controls 1 and 3 months postoperatively.

Conclusion

Uncomplicated phacoemulsification resulted in greater increases in SCP-VD, MT and CT in patients with early DR without preoperative DME than in controls.

Telemedicine-assisted structured self-monitoring of blood glucose in management of T2DM results of a randomized clinical trial

BACKGROUND

This prospective study aimed to compare telemedicine-assisted structured self-monitoring of blood glucose(SMBG) with a traditional blood glucose meter (BGM) in adults of type 2 diabetes mellitus (T2DM).

METHODS

Adult participants with T2DM were assigned to an intervention group or a control group. The patients in the intervention group received a connected BGM with real-time data submission as well as individual needs-based tele-coaching to address and improve motivation and daily diabetes self-management. The patients in the control group received a traditional BGM. Changes in glycated hemoglobin(HbA1c), low blood glucose index(LBGI), and diabetes self-management behaviors were analyzed.

RESULTS

The study demonstrated the superiority of the telemedicine-assisted structured SMBG versus the traditional BGM for improving HbA1c. Additionally, the telemedicine-assisted SMBG reduced the risk of hypoglycemia and enhanced diabetes self-management behaviors, as differences in the LBGI and the Diabetes Self-Management Questionnaire(DSMQ) results between the groups after 6 months were found to be significant.

CONCLUSIONS

Telemedicine-assisted structured SMBG helps physicians and patients to achieve a specific level of glycemic control and reduce hypoglycemia. The use of coaching applications and telemedicine-assisted SMBG indicated beneficial effects for T2DM self-management, which may help limit disease progression.

TRIAL REGISTRATION

Chinese Clinical Trail Registry No: ChiCTR2300072356 on 12/06/2023. Retrospectively registered.

Systemic and vitreous biomarkers - new insights in diabetic retinopathy

PURPOSE

Diabetic retinopathy (DR) is a microvascular inflammatory and neurodegenerative disease. The purpose of this study was to analyze the relationship between DR severity and the levels of potential biomarkers in the serum and/or vitreous.

METHODS

A prospective, consecutive, controlled, observational study was performed between June 2018 and January 2020. Blood and vitreous samples were collected on the day of vitrectomy in patients without diabetes and in patients with diabetes with epiretinal membrane, macular edema, and indication for vitrectomy.

RESULTS

Transthyretin (TTR) was the only blood biomarker with levels statistically higher in patients with diabetes (p = 0.037). However, no correlation with DR severity was observed. Erythropoietin (EPO) was the only blood biomarker whose levels were associated with DR severity (p = 0.036). In vitreous samples, levels of EPO (p = 0.011), interleukin (IL)-6 (p < 0.001), IL-8 (p < 0.001), IL-17 (p = 0.022), monokine induced by interferon-γ (MIG) (p < 0.001), and interferon gamma-induced protein 10 (IP-10) (p = 0.005) were significantly higher in patients with diabetes. Additionally, in vitreous, IL-6, IL-8, MIG, and IPL-10 levels were also higher in more severe DR cases (p < 0.05).

CONCLUSIONS

Among the studied biomarkers, vitreous IL-6, IL-8, MIG, and IP-10 were the ones whose levels had the strongest coherent relationship with DR severity prediction and, thus, have the best potential post-vitrectomy prognostic value.

Tasquinimod efficacy and S100A9 expression in glucose-treated HREC cells

PURPOSE

Diabetic retinopathy (DR) is one of the leading causes of blindness in working-aged people. Few studies were on the relationship between S100 Calcium Binding Protein A9 (S100A9) protein and DR, and none on endothelial cells induced by tasquinimod in high glucose. Therefore, we assessed the relationship between tasquinimod and S100A9 in DR.

METHODS

DR pathogenesis was simulated using high-glucose-induced human retinal endothelial cells (HRECs) to study the mRNA expression of s100a9, thrombospondin-1 (tsp-1), hypoxia-inducible factor 1-alpha (hif1-α), intercellular adhesion molecule 1 (icam-1), and vascular endothelial growth factor (vegf) after tasquinimod treatment. The protein expression of S100A9, TSP-1, extracellular signal-regulated kinase (ERK), ICAM-1 and VEGF was also analyzed.

RESULT

A total of 28 eyes of 26 patients were included in this experiment. A significantly higher expression of S100A9 as well as enhanced proliferation and mobility was observed in the high-glucose-treated HRECs compared with that in low-glucose-treated cells. However, these were significantly inhibited when treated with high glucose with 50 μM tasquinimod. The mRNA expression of tsp-1 was increased, whereas that of hif1-α, icam-1 and vegf was decreased after tasquinimod treatment. Western blot indicated the increased TSP-1 but decreased ERK, ICAM-1 and VEGF expression after treating with tasquinimod.

CONCLUSION

High glucose promoted the expression of s100a9, S100A9 protein in DR patients and HRECs. Tasquinimod inhibited the proliferation, migration and lumen formation of HRECs under a high glucose environment. Tasquinimod might play a vital role in inhibiting angiogenesis through inducing TSP-1 and inhibiting VEGF, ICAM-1 and ERK.

Circulating Biomarkers of Inflammation and Endothelial Activation in Diabetic Retinopathy

Inflammation and endothelial activation play a pivotal role in development and progression of diabetic retinopathy (DR), a vision-threatening complication of diabetes mellitus (DM) and the leading cause of blindness in the working age population. Easily accessible and validated biomarkers for DR early diagnosis and progression are required for use in clinical trials: here, we reviewed the available literature to understand the association of circulating levels of selected markers of inflammation and endothelial activation with the presence of nonproliferative and proliferative DR (NPDR and PDR) and investigate the relationship between their systemic and ocular levels. We additionally provide data synthesis and perform statistical analysis for interpretation of the collected evidence. CRP, IL-1β, IL-6, TNFα, sICAM1, and sVCAM1 circulating levels were increased in subjects with DM compared to healthy individuals. Moreover, TNFα and sVCAM1 showed increasing systemic levels with DR presence and severity; circulating CRP increased with the transition from no DR to NPDR, whereas IL-6 was increased in PDR compared to NDPR stages. The relationship between ocular and systemic concentrations of these proteins remained unclear due to the low number of studies with matched sampling. In conclusion, the available data supports the use of systemic biomarkers of inflammation and endothelial activation to identify DM status and DR severity. These systemic biomarkers are likely reflecting an overall state of inflammation and vascular activation in different tissues of the body, including the eyes. Prospective, longitudinal datasets are required to validate these biomarkers as predictors of early DR presence, of DR progression, or for disease monitoring.

Inflammatory and angiogenic biomarkers in diabetic retinopathy

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus (DM) and a leading cause of blindness in working-age adults in developed countries. Numerous investigations have recognised inflammation and angiogenesis as important factors in the development of this complication of diabetes. Current methods of DR treatment are predominantly used at advanced stages of the disease and could be associated with serious side effects. Therefore, new diagnostic methods are needed in order to identify the initial stages of DR as well as monitoring the effects of applied therapy. Biochemical biomarkers are molecules found in blood or other biological fluid and tissue that indicate the existence of an abnormal condition or disease. They could be a valuable tool in detecting early stages of DR, identifying patients most susceptible to retinopathy progression and monitoring treatment outcomes. Biomarkers related to DR can be measured in the blood, retina, vitreous, aqueous humour and recently in tears. As the retina represents a small part of total body mass, a circulating biomarker for DR needs to be highly specific. Local biomarkers are more reliable as indicators of the retinal pathology; however, obtaining a sample of aqueous humour, vitreous or retina is an invasive procedure with potential serious complications. As a non-invasive novel method, tear analysis offers a promising direction in further research for DR biomarker detection. The aim of this paper is to review systemic and local inflammatory and angiogenic biomarkers relevant to this sight threatening diabetic complication.

Elevated vitreous Lipocalin-2 levels of patients with proliferative diabetic retinopathy

BACKGROUND

Lipocalin-2 (LCN2) is a novel adipokine with potential roles in obesity, insulin resistance, and inflammation. This study aims to assess the concentrations of LCN2 and vascular endothelial growth factor (VEGF) expressed in the vitreous humors of patients with proliferative diabetic retinopathy (PDR).

METHODS

The concentrations of LCN2 and VEGF were measured from the vitreous of 67 patients undergoing vitrectomy (20 controls and 47 PDR) via enzyme-linked immunosorbent assay (ELISA). Patients with non-ocular pathology that could elevate the LCN2 level in the vitreous were excluded. PDR activity and a history of panretinal photocoagulation were used for further grouping analysis.

RESULTS

The vitreous concentration of LCN2 was statistically significantly higher in the PDR group compared to the control group (63,522 (30,009) pg/ml versus 1663 (1191) pg/ml, respectively; P < 0.001). VEGF level was also significantly higher in the PDR group than in the control group (1038 (1326) pg/ml versus 9 pg/ml, respectively; P < 0.001). The mean vitreous LCN2 and VEGF levels in active PDR patients were significantly higher than that of the inactive PDR patients. The mean LCN2 concentration in vitreous humor was significantly lower in the 28 PDR patients with a history of complete PRP (37,304 (16,651) pg/mL) in comparison with 19 PDR patients without preperformed panretinal photocoagulation or with preperformed incomplete panretinal photocoagulation (79,796 (24,391) pg/mL). A significant correlation between the vitreous LCN2 level and VEGF level was found in patients with PDR (R = 0.34; P = 0.019).

CONCLUSIONS

This report shows a significant increase of LCN2 in the vitreous fluid of patients with PDR and present a significant correlation between LCN2 and VEGF, suggesting LCN2 might be involved in the pathogenesis of PDR.

Central Macular Thickness in Diabetic Macular Edema

Context

Retinal microvascular dysfunction differs in macular edema lesions in the two eyes of the same patient with diabetic retinopathy.

Objective

To evaluate the relationship between central macular thickness (CMT) and metabolic/systemic factors including anthropometric and laboratory findings, in patients with regressed diabetic retinopathy and a history of pars plana vitrectomy (PPV) combined with internal limiting membrane peeling in one eye.

Subjects and Methods

Forty-two eyes with PPV and the same patients' fellow 42 eyes (without PPV) included this study. Fasting blood samples of these 42 diabetics were collected to study adiponectin levels and other routine parameters.

Results

The average hemoglobinA1c value was 7.3±1.3%. CMT of the vitrectomized eyes were significantly correlated with atherogenic index of plasma, total cholesterol, low density lipoprotein cholesterol and uric acid (UA). On the other hand, CMT of the nonvitrectomized fellow eyes significantly correlated with glucose levels and diabetes duration. Adiponectin, adiponectin/body mass index, adiponectin/fibrinogen were found significantly higher in the subgroup with CMT≥300μm in the vitrectomized eyes (P<0.05). UA levels were higher in the subgroup with CMT≥300μm in the fellow (nonvitrectomized) eyes (P<0.05).

Conclusions

Although there was no relationship between CMT and hemoglobinA1c values, CMT seemed to be affected by atherogenicity, prooxidant chemical alterations in the course of inflammation, so determination of adiponectin and UA levels may be suggested before surgery to predict the atherosclerotic damage and the postoperative CMT value. Vitrectomy performed at the proper time may be helpful in metabolic remodeling process of the retinal tissue along with life style changes, well control of diabetes, and intraocular treatments.

Diabetic Retinopathy-An Underdiagnosed and Undertreated Inflammatory, Neuro-Vascular Complication of Diabetes

Diabetes mellitus is a world-wide epidemic and diabetic retinopathy, a devastating, vision-threatening condition, is one of the most common diabetes-specific complications. Diabetic retinopathy is now recognized to be an inflammatory, neuro-vascular complication with neuronal injury/dysfunction preceding clinical microvascular damage. Importantly, the same pathophysiologic mechanisms that damage the pancreatic β-cell (e.g., inflammation, epigenetic changes, insulin resistance, fuel excess, and abnormal metabolic environment), also lead to cell and tissue damage causing organ dysfunction, elevating the risk of all complications, including diabetic retinopathy. Viewing diabetic retinopathy within the context whereby diabetes and all its complications arise from common pathophysiologic factors allows for the consideration of a wider array of potential ocular as well as systemic treatments for this common and devastating complication. Moreover, it also raises the importance of the need for methods that will provide more timely detection and prediction of the course in order to address early damage to the neurovascular unit prior to the clinical observation of microangiopathy. Currently, treatment success is limited as it is often initiated far too late and after significant neurodegeneration has occurred. This forward-thinking approach of earlier detection and treatment with a wider array of possible therapies broadens the physician's armamentarium and increases the opportunity for prevention and early treatment of diabetic retinopathy with preservation of good vision, as well the prevention of similar destructive processes occurring among other organs.