Clinical Features and Vitreous Biomarkers of Early-Onset Type 2 Diabetes Mellitus Complicated with Proliferative Diabetic Retinopathy

Association between age at diabetes diagnosis and the development and progression of diabetic retinopathy

This study aimed to investigate the relationship between age at diabetes diagnosis (ADD) and the development and progression of diabetic retinopathy (DR). This study combined analysis of the National Health and Nutrition Examination Survey (NHANES) data with Mendelian randomization (MR). We employed regression models, propensity score matching, generalized additive model smoothing splines (GAM), random forest algorithms, and other analytical techniques. Cross-sectional analysis of NHANES data (n = 877) showed that the DR group had a significantly younger ADD compared to the DR-free group (P < 0.001). Regression analysis revealed a significant inverse association between ADD and DR prevalence (OR = 0.96, P < 0.001). MR analysis further supported this inverse relationship (OR = 0.42, P = 0.003). Two non-linear analytical approaches identified peak DR occurrence probability at ages 24.45 (GAM) and 24.2 (Shapley additive explanations dependence plots). Additionally, younger ADD was associated with increased DR severity across all categories (P < 0.05). In conclusion, older ADD was associated with a protective effect against the development and progression of DR, as supported by both analysis of NHANES data and MR. These findings underscore the importance of increased vigilance and more frequent screening for DR in patients diagnosed with diabetes at a young age.

Genetically predicted inflammatory cytokine levels and risk of retinitis pigmentosa

PURPOSE

This study aims to estimate the potential causal relationship between genetically predicted levels of inflammatory cytokine and retinitis pigmentosa (RP) by performing Mendelian randomization (MR).

METHODS

Single nucleotide polymorphisms (SNPs) were identified as instrumental variables (IVs) from publicly available genome-wide association study datasets. Inverse-variance weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode methods were applied in this MR analysis. IVW and MR-Egger were used to confirm heterogeneity and pleiotropy of identified IVs. Leave-one-SNP-out analysis was used to identify SNPs with potential impact.

RESULTS

IVW results revealed that elevated levels of Tumor Necrosis Factor Alpha (TNF-α), Macrophage Inflammatory Protein-1a (MIP1a), and Monokine Induced by Gamma Interferon (MIG) were associated with higher RP risk (OR = 2.358, p = 0.050; OR = 2.583, p = 0.013; OR = 1.851, p = 0.015), while elevated levels of Interleukin-16 (IL-16) were associated with reduced RP risk (OR = 0.723, p = 0.019). The results of heterogeneity and pleiotropy (p > 0.05) confirmed there was no pleiotropy and heterogeneity in our IVW analysis. The association of TNF-α, MIP1a, MIG and IL-16 with RP from sensitivity analyses using these two sets of restricted IVs remained stable.

CONCLUSION

Our study provides evidence of potential causal relationships between several circulating cytokine levels and RP. Elevated levels of TNF-α, MIP1a, and MIG are associated with a higher risk of RP, while elevated levels of IL-16 are associated with a lower risk of RP. These cytokines may be novel biomarkers and therapeutic targets for RP.

Transcriptional patterns of human retinal pigment epithelial cells under protracted high glucose

BACKGROUND

The retinal pigment epithelium (RPE) is essential for retinal homeostasis. Comprehensively exploring the transcriptional patterns of diabetic human RPE promotes the understanding of diabetic retinopathy (DR).

METHODS AND RESULTS

A total of 4125 differentially expressed genes (DEGs) were screened out from the human primary RPE cells subjected to prolonged high glucose (HG). The subsequent bioinformatics analysis is divided into 3 steps. In Step 1, 21 genes were revealed by intersecting the enriched genes from the KEGG, WIKI, and Reactome databases. In Step 2, WGCNA was applied and intersected with the DEGs. Further intersection based on the enrichments with the GO biological processes, GO cellular components, and GO molecular functions databases screened out 12 candidate genes. In Step 3, 13 genes were found to be simultaneously up-regulated in the DEGs and a GEO dataset involving human diabetic retinal tissues. VEGFA and ERN1 were the 2 starred genes finally screened out by overlapping the 3 Steps.

CONCLUSION

In this study, multiple genes were identified as crucial in the pathological process of RPE under protracted HG, providing potential candidates for future researches on DR. The current study highlights the importance of RPE in DR pathogenesis.

Relaxation of mitochondrial hyperfusion in the diabetic retina via N6-furfuryladenosine confers neuroprotection regardless of glycaemic status

The recovery of mitochondrial quality control (MQC) may bring innovative solutions for neuroprotection, while imposing a significant challenge given the need of holistic approaches to restore mitochondrial dynamics (fusion/fission) and turnover (mitophagy and biogenesis). In diabetic retinopathy, this is compounded by our lack of understanding of human retinal neurodegeneration, but also how MQC processes interact during disease progression. Here, we show that mitochondria hyperfusion is characteristic of retinal neurodegeneration in human and murine diabetes, blunting the homeostatic turnover of mitochondria and causing metabolic and neuro-inflammatory stress. By mimicking this mitochondrial remodelling in vitro, we ascertain that N6-furfuryladenosine enhances mitochondrial turnover and bioenergetics by relaxing hyperfusion in a controlled fashion. Oral administration of N6-furfuryladenosine enhances mitochondrial turnover in the diabetic mouse retina (Ins2Akita males), improving clinical correlates and conferring neuroprotection regardless of glycaemic status. Our findings provide translational insights for neuroprotection in the diabetic retina through the holistic recovery of MQC.

Variability of Replicates of Intraocular Inflammatory Biomarkers in Ocular Fluid Samples Analyzed with Multiplex Assays

Purpose

Certain factors such as instrumental and sample processing errors may contribute to variability of ocular biofluid samples when they are run as replicates with multiplex assays. There is a paucity of literature on the variability of replicates in multiplex assays. This study aims to evaluate whether there is significant variability in replicate analyses of multiplex assays.

Methods

A total of 152 human ocular biofluid samples (51 aqueous humor and 101 vitreous) were collected and assayed for 27 cytokine biomarker concentrations (pg/mL). Samples were evaluated as replicates (duplicate analysis) at four different time points. Statistical methods including paired samples t-test, 3-way ANOVA, intraclass correlation coefficient (ICC; <0.5-0.75=poor-moderate, 0.75->0.90 =good-excellent reliability), and coefficients of variation (CV) were employed to evaluate for statistical significance, with Bonferroni corrected P=0.002.

Results

Among the 4104 biomarker replicate assays for aqueous humor and vitreous, two analytes (PDGF-BB and IL-7) had a statistically significant difference between the sampled concentrations of the replicates in vitreous samples (mean (diff)=2.05, P<0.001, mean (diff)=1.56, P<0.001, respectively). Majority of the ICC values fell within the good-excellent range (86% of samples) with a minority falling in the poor-moderate range (14% of samples). More variability was noted in the vitreous humour, with five analytes (IL-2, IL-10, IL-12(p70), IL-13, IL-17) demonstrating an average ICC of less than 0.5. The CV calculated for each set of replicates suggested that 93% of replicates had an acceptable level of quantitative assay variability (CV<20%).

Conclusion

This study demonstrates that the analysis of most biomarkers in ocular fluids may not require the use of replicates. However, certain analytes such as PDGF-BB and IL-7 may require the use of replicates to ensure reliable results. Caution should be taken when applying these findings to other laboratory settings as our study was conducted by an experienced technician using a standardized protocol. In less standardized settings, replicates may be required in order to ensure accuracy of results. These findings may guide researchers with the design of their studies on ophthalmic biomarker analysis.

Complications and Treatment of Early-Onset Type 2 Diabetes

Context

Global reports have revealed a dramatic rise in the number of patients diagnosed with type 2 diabetes (T2DM) over the past three decades in all age groups, even in children and adolescents. The physiologic phenomenon of insulin resistance during puberty, as well as genetic and epigenetic factors, are implicated in this phenomenon. It seems that patients with early-onset T2DM experience a more aggressive clinical course; however, limited treatments available for these patients pose a challenge. This narrative review intends to scrutinize the micro- and macrovascular complications and treatments of patients with early-onset T2DM.

Methods

The literature search was conducted in the PubMed database to identify all relevant original English articles published from the beginning of 2018 until January 2023.

Results

Vascular complications, such as albuminuria, hypertension, cardiovascular diseases, and retinopathy, were seen to be more common in early-onset T2DM compared to type 1 diabetes. The odds ratio of vascular complications was higher in early-onset compared to late-onset T2DM. In children and adolescents with T2DM, the only approved medications included metformin, insulin, and glucagon-like peptide-1 agonists. Treatment of early-onset T2DM with metformin monotherapy cannot yield durable glycemic control, and most patients need early combination therapy.

Conclusions

During the past years, the frequency of early-onset T2DM has been growing at an alarming rate. Vascular complications in these patients seem more aggressive and more challenging to control. Hence, further clinical trials should be conducted to develop novel therapeutic approaches and evaluate their long-term benefits in terms of glycemic control and preventing future complications.

Elucidating glial responses to products of diabetes-associated systemic dyshomeostasis

Diabetic retinopathy (DR) is a leading cause of blindness in working age adults. DR has non-proliferative stages, characterized in part by retinal neuroinflammation and ischemia, and proliferative stages, characterized by retinal angiogenesis. Several systemic factors, including poor glycemic control, hypertension, and hyperlipidemia, increase the risk of DR progression to vision-threatening stages. Identification of cellular or molecular targets in early DR events could allow more prompt interventions pre-empting DR progression to vision-threatening stages. Glia mediate homeostasis and repair. They contribute to immune surveillance and defense, cytokine and growth factor production and secretion, ion and neurotransmitter balance, neuroprotection, and, potentially, regeneration. Therefore, it is likely that glia orchestrate events throughout the development and progression of retinopathy. Understanding glial responses to products of diabetes-associated systemic dyshomeostasis may reveal novel insights into the pathophysiology of DR and guide the development of novel therapies for this potentially blinding condition. In this article, first, we review normal glial functions and their putative roles in the development of DR. We then describe glial transcriptome alterations in response to systemic circulating factors that are upregulated in patients with diabetes and diabetes-related comorbidities; namely glucose in hyperglycemia, angiotensin II in hypertension, and the free fatty acid palmitic acid in hyperlipidemia. Finally, we discuss potential benefits and challenges associated with studying glia as targets of DR therapeutic interventions. In vitro stimulation of glia with glucose, angiotensin II and palmitic acid suggests that: 1) astrocytes may be more responsive than other glia to these products of systemic dyshomeostasis; 2) the effects of hyperglycemia on glia are likely to be largely osmotic; 3) fatty acid accumulation may compound DR pathophysiology by promoting predominantly proinflammatory and proangiogenic transcriptional alterations of macro and microglia; and 4) cell-targeted therapies may offer safer and more effective avenues for DR treatment as they may circumvent the complication of pleiotropism in retinal cell responses. Although several molecules previously implicated in DR pathophysiology are validated in this review, some less explored molecules emerge as potential therapeutic targets. Whereas much is known regarding glial cell activation, future studies characterizing the role of glia in DR and how their activation is regulated and sustained (independently or as part of retinal cell networks) may help elucidate mechanisms of DR pathogenesis and identify novel drug targets for this blinding disease.

Novel biomarkers and therapeutic approaches for diabetic retinopathy and nephropathy: Recent progress and future perspectives

The global burden due to microvascular complications in patients with diabetes mellitus persists and even increases alarmingly, the intervention and management are now encountering many difficulties and challenges. This paper reviews the recent advancement and progress in novel biomarkers, artificial intelligence technology, therapeutic agents and approaches of diabetic retinopathy and nephropathy, providing more insights into the management of microvascular complications.