Role of Cytokines in Ranibizumab Therapy for Macular Edema in Patients with Central Retinal Vein Occlusion

Development of high-performance point-of-care aqueous VEGF detection system and proof-of-concept validation in RVO patients

OBJECTIVES

To develop a sensitive point-of-care testing (POCT) aqueous vascular endothelial growth factor (VEGF) detection system, and assess its role for predicting the response to anti-VEGF treatment in macular edema secondary to retinal vein occlusion (RVO-ME) patients.

METHODS

An automatic point-of-care aqueous humor Magnetic Particle Chemiluminescence Enzyme Immuno-Assay (MPCLEIA) VEGF detection system was developed. The predictive values of aqueous cytokine levels, in combination with imaging parameters, on anatomical treatment response (ATR, the relative central macular thickness change [ΔCMT/bl-CMT]) were analyzed.

RESULTS

The automatic MPCLEIA system was able to provide results in 45 min with only 20 μL sample. Among the 57 eyes with available pre- and post-treatment evaluation, ATR significantly correlated with levels of interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1) and VEGF measured by Luminex xMAP platform, and VEGF measured by MPCLEIA. Optimal cut-off values for these biomarkers were 13.26 ng/L, 23.57 ng/L, 1,110.12 ng/L, 105.52 ng/L, and 85.39 ng/L, respectively. Univariate analysis showed significant associations between ATR category (good response if ATR≤-25 % or poor response otherwise) and IL-6, IL-8, MCP-1, VEGF-xMAP, and VEGF-MPCLEIA (p<0.05). Multivariate logistic regression revealed that ATR category was significantly associated with aqueous VEGF-MPCLEIA (p=0.006) and baseline(bl)-CMT (p=0.008). Receiver operating characteristics analysis yielded an AUC of 0.959 for the regression model combining VEGF-MPCLEIA and bl-CMT, for predicting ATR category.

CONCLUSIONS

Our novel MPCLEIA-based automatic VEGF detection system enables accurate POCT of aqueous VEGF, which shows promise in predicting the treatment response of RVO-ME to anti-VEGF agents when combined with bl-CMT.

Longitudinal analysis of aqueous humour cytokine expression and OCT-based imaging biomarkers in retinal vein occlusions treated with anti-vascular endothelial growth factor therapy in the IMAGINE study

BACKGROUND/OBJECTIVES

Retinal vein occlusion (RVO) is the second most common retinal vascular disorder. Despite promising advances with anti-VEGF therapy, select patients are unresponsive to therapy. A precision medicine-based approach for therapeutic decision-making based on underlying biomarkers may facilitate treatment based on the underlying pathway. This study aims to identify the baseline and longitudinal cytokine profiles of RVO-related macular oedema and correlating these expression profiles with higher order OCT features using a novel retinal segmentation and feature extraction platform.

SUBJECTS/METHODS

The IMAGINE study is a post-hoc assessment of aqueous humour cytokines with correlation to higher level analysis of imaging studies. OCT scans underwent machine learning enhanced segmentation of the internal limiting membrane (ILM), ellipsoid zone (EZ) and retinal pigment epithelium (RPE), as well as evaluating volumetric fluid metrics. Samples of aqueous humour were obtained at baseline, as well as months 4 and 9 prior to treatment. These samples were analysed for the expression of multiple cytokines. Patients were divided into Responders and Non-Responders based on OCT profiles. Additionally, patients were categorised as a Rebounder if their CST increased by 50% after initial improvement.

RESULTS

Twenty-six eyes were included. The OCT-based response schema identified 21 Responders (81%) and 5 Non-Responders (19%). VEGF levels directly correlated with intraretinal fluid volume and angiogenin was inversely correlated with fluid indices. Multiple cytokines, including ANGPTL4, were directly correlated with ellipsoid zone disruption. The baseline VEGF levels were significantly higher in all responders compared to Non-Responders (p = 0.02). Rebounders tended to have significantly decreased levels of angiogenin and TIMP-1 (p = 0.019, p = 0.015).

CONCLUSIONS

Cytokine expression was linked to specific OCT features and treatment response in RVO. Identification of an imaging phenotype that could serve as a surrogate for underlying active disease pathways could enhance treatment decision-making and precision medicine.

Analysis of the Cytokine Expression in the Aqueous Humor of Individuals with BRVO-Associated Macular Edema

Purpose

This study aimed to determine the expression levels of vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in the aqueous humor of patients with macular edema (ME) caused by branch retinal vein occlusion (BRVO), as well as to investigate the relationship between the cytokines as mentioned earlier and best-corrected visual acuity (BCVA), ME, and the degree of ME from the molecular level.

Methods

In a prospective observational study, fluorescein fundus angiography (FFA) and optical coherence tomography (OCT) were used to classify 58 patients with non-ischemic BRVO-ME into three groups according to the degree of ME: 14-mild, 17-moderate, and 27-severe. The specific concentration of IL-6, VEGF, ICAM-1, and VCAM-1 in the aqueous humor was detected using the BD CSCanto™ II Flow Cytometer (US). Spearman or Pearson correlation analysis was used to test the correlation between the levels of BCVA and severity of ME and the expression levels of IL-6, VEGF, ICAM-1, and VCAM-1 in the aqueous humor.

Results

According to the obtained data, BCVA did not correlate with the severity of ME, and these four cytokines expression levels in patients' aqueous humor (P > 0.05). Moreover, BCVA did not correlate with mild, moderate, or severe ME as well (P > 0.05). However, the levels of these four cytokines were correlated with the severity of the ME. These underlined cytokines were linked to the mild, moderate, and severe degrees of ME. VEGF was also significantly correlated (r > 0.8, P < 0.0001) with the severity of ME.

Conclusions

This study suggests that the severity of ME in BRVO-ME patients is significantly correlated with the expression levels of IL-6, VEGF, ICAM-1, and VCAM-1 in the aqueous humor. Lowering the level of disease-associated cytokines may potentially reduce the degree of ME. Therefore, an in-depth study of the levels and the relationship may provide some evidence for the pathogenesis, treatment, and prevention of BRVO-ME.

The impact of laboratory findings and optical coherence tomography biomarkers on response to intravitreal anti-VEGF treatment in patients with retinal vein occlusion

AIMS

To investigate potential laboratory and imaging biomarkers as treatment response predictors to intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents in patients with retinal vein occlusion (RVO).

METHODS

Participants in this prospective study were 53 patients with treatment naïve macular edema secondary to RVO, treated with intravitreal anti-VEGF agents and followed-up for 12 months. At baseline, all participants underwent best-corrected visual acuity measurement, dilated fundoscopy, optical coherence tomography and fluorescein angiography (FFA), while full blood count and biochemical analysis of various parameters was also performed. At month 12, treatment response was examined and classified as "favorable" or "non-response". Potential associations between laboratory/imaging biomarkers and treatment response were assessed.

RESULTS

Univariate analysis showed that "favorable" response at month 12 after initiation of anti-VEGF treatment was correlated with baseline central subfield thickness (CST) < 464 μm (p < 0.001), absence of subretinal fluid (p = 0.004), absence of hyperreflective foci (HF) (p = 0.004), intact ellipsoid zone (EZ) and external limiting membrane (ELM) (p < 0.001 and p = 0.001, respectively), absence of epiretinal membrane (ERM) (p = 0.020) and absence of macular ischemia on FFA (p < 0.001), while increased monocytes-to-lymphocytes ratio was also associated with "favorable" treatment response (p = 0.010). All other laboratory parameters did not reach statistical significance. However, at the multivariate analysis, EZ and ELM status, HF, macular ischemia and monocytes-to-lymphocytes ratio were found to be independent predictors of treatment response.

CONCLUSIONS

Intact EZ and ELM, absence of HF, absence of macular ischemia and increased monocytes-to-lymphocytes ratio at baseline can predict "favorable" treatment response in patients with treatment naïve macular edema secondary to RVO.

A Review of Intraocular Biomolecules in Retinal Vein Occlusion: Toward Potential Biomarkers for Companion Diagnostics

Retinal vein occlusion (RVO) is one of the most common retinal vascular diseases. The pathogenesis of RVO is multifactorial and involves a complex interplay among a variety of vascular and inflammatory mediators. Many cytokines, chemokines, growth factors, and cell adhesion molecules have been reported to be implicated. Treatments for RVO are directed at the management of underlying risk factors and vision-threatening complications, including macula edema (ME) and neovascularization. Intravitreal anti-VEGF agents are currently considered as the first-line treatment for ME secondary to RVO (RVO-ME), but a substantial proportion of patients responded insufficiently to anti-VEGF agents. Since RVO-ME refractory to anti-VEGF agents generally responds to corticosteroids and its visual outcome is negatively correlated to disease duration, prediction of treatment response at baseline in RVO-ME may significantly improve both cost-effectiveness and visual prognosis. Several bioactive molecules in the aqueous humor were found to be associated with disease status in RVO. This review aims to present a comprehensive review of intraocular biomolecules reported in RVO, including VEGF, IL-6, IL-8, MCP-1, sICAM-1, IL-12, IL-13, sVEGFR-1, sVEGFR-2, PDGF-AA, etc., highlighting their association with disease severity and/or phenotype, and their potential roles in prognostic prediction and treatment selection. Some of these molecules may serve as biomarkers for aqueous humor-based companion diagnostics for the treatment of RVO in the future.

AQUEOUS HUMOR CYTOKINE LEVELS AND REBOUND MACULAR EDEMA AFTER CONBERCEPT TREATMENT IN PATIENTS WITH CENTRAL RETINAL VEIN OCCLUSION

PURPOSE

This study aimed to investigate the effect of intravitreal conbercept (IVC) injections on the aqueous humor concentrations of angiogenic and inflammatory cytokines in patients with macular edema (ME) due to central retinal vein occlusion and to determine whether changes in cytokine levels after IVC are associated with the development of rebound ME.

METHODS

Forty-nine patients with ME caused by central retinal vein occlusion were included in this retrospective study. Monthly doses of IVC were administered for three months, followed by a Pro Re Nata dosing regimen. Rebound ME was defined as ≥110% increase in the foveal thickness compared with the baseline. Whenever injections were administered, aqueous humor samples were obtained. Multiplex bead assay was used to measure seven angiogenic and inflammatory cytokines in aqueous humor samples.

RESULTS

At baseline, patients with central retinal vein occlusion showed significantly higher aqueous humor concentrations of vascular endothelial growth factor, placental growth factor, monocyte chemoattractant protein-1, platelet-derived growth factor-AA, IL-6, IL-8, and IL-12. At 1-month and 2-month follow-up after IVC, significantly decreased concentrations of all cytokines were observed. During the 12-month follow-up period, 6 of the 49 eyes (12.2%) showed rebound ME after IVC. Patients with rebound ME showed significantly elevated levels of inflammatory but not angiogenic cytokines.

CONCLUSION

Angiogenic and inflammatory cytokines were overexpressed in patients with ME caused by central retinal vein occlusion. Conbercept treatment influenced the concentrations of various inflammatory cytokines and reduced aqueous vascular endothelial growth factor and placental growth factor concentrations. Rebound ME may occur due to disruption of the balance between angiogenic and inflammatory cytokines and an accompanying excess of inflammatory cytokines but not angiogenic cytokines, after antivascular endothelial growth factor therapy.

A dynamic nomogram for predicting diabetic macular edema in type 2 diabetes patients based on plasma cytokines

OBJECTIVE

This study investigated changes of plasma cytokines and aimed to build a dynamic nomogram for diabetic macular edema (DME) in type 2 diabetes mellitus (T2DM).

METHODS

In a pilot cohort, plasma samples were selected from 9 T2DM patients and 9 DME patients to screen for cytokine differences. The screening cytokines were then validated by enzyme-linked immunoassay in a cohort, which contained 100 DME (DME group) and 100 T2DM patients without DME (T2DM group). A dynamic nomogram for predicting DME was developed, based on the plasma cytokines.

RESULTS

In the pilot cohort, 11 plasma cytokines were significantly increased in the DME group. In the validation cohort, platelet-derived growth factor (PDGF)-BB, tissue inhibitors of metalloproteinase (TIMP)-1, angiopoietin (ANG-1), and vascular endothelial cell growth factor receptor (VEGFR)-2 were confirmed to be significantly elevated in the DME group. The dynamic nomogram demonstrated good calibration and discrimination, with an area under the receiver operating characteristic curve (AUC) of 0.88. In the test set, sensitivity, specificity, and AUC were 73.3%, 80.0%, and 0.84, respectively.

CONCLUSION

Plasma cytokines were closely associated with DME. A novel dynamic monogram including ANG-1, PDGF-BB, TIMP-1, and VEGFR2 was a novel tool for predicting DME.

Establishment of a pigmented murine model abundant with characteristics of retinal vein occlusion

Retinal vein occlusion (RVO) is a vascular disease that represents characteristic retinal hemorrhage and dilated retinal veins. Despite its clinical importance, its pathogenesis remains largely unknown because of limited opportunities to acquire human retinal samples. Therefore, an animal model that reproduces the clinical features of RVO patients is required for further investigation. In this study, we established a pigmented murine RVO model that reproduced characteristic fundus appearances similar to human RVO findings. Retinal edema in this model was observed in both optical coherence tomography and histological analysis, which is a clinically important outcome. With quantitative real-time PCR analysis on retinal samples, we revealed that the mRNA level of vascular endothelial growth factor (VEGF) increased in the retina induced RVO. Moreover, this retinal edema was reduced by intravitreal injection of anti-VEGF antibody. These results were consistent with human clinical knowledge and suggested that this model could be a useful tool for research into new therapeutic approaches.

Retinal Microcirculation and Cytokines as Predictors for Recurrence of Macular Edema after Intravitreal Ranibizumab Injection in Branch Retinal Vein Occlusion

Purpose: To investigate the relationship between retinal blood flow, presence or absence of recurrence of macular edema, and levels of cytokines, after intravitreal ranibizumab injection (IRI) in patients with branch retinal vein occlusion (BRVO). Methods: In 47 patients with BRVO and macular edema, we used laser speckle flowgraphy (LSFG) to measure the relative flow volume (RFV) of the retinal arteries and veins passing through the optic disc in the occluded and non-occluded regions of the retina before and after IRI. Aqueous humor samples were obtained at the time of IRI. Levels of vascular endothelial growth factor (VEGF), soluble VEGF receptor (sVEGFR)-1, sVEGFR-2, placental growth factor (PlGF), platelet-derived growth factor (PDGF)-AA, soluble intercellular adhesion molecule (sICAM)-1, monocyte chemoattractant protein 1 (MCP-1), interleukin (IL)-6, IL-8, IL-12 (p70), IL-13 and interferon-inducible 10-kDa protein (IP-10) were measured by the suspension array method. Patients were categorized into two groups on the basis of whether or not macular edema recurred at 2 months after IRI: the nonrecurrent group, n = 24; and the recurrent group, n = 23. Results: In the veins of the occluded region, RFV showed a significant difference between baseline and 1 month after IRI (p < 0.001) in the recurrent group and the percent change of RFV showed a significant difference between the recurrent and nonrecurrent groups (p = 0.005). Furthermore, we found a significant negative correlation between RFV in the veins of the occluded region and aqueous levels of MCP-1, IL-8 and IP-10 at baseline (p = 0.029, p = 0.035, and p = 0.039, respectively). In the recurrent group, the arteries and veins of the non-occluded and occluded regions showed no significant association between RFV and the aqueous levels of any factors. Conclusions: These findings suggested that a decrease in RFV in the veins of the occluded region might be associated with the recurrence of macular edema and that the recurrence might depend on the change in RFV in the veins of the occluded region rather than the levels of cytokines.

Comparison of the Effect of Intravitreal Conbercept and Ranibizumab on Aqueous Humor Cytokines in Central Retinal Vein Occlusion-Related Macular Edema

Purpose: To analyze changes in the levels of angiogenic and inflammatory cytokines following the administration of intravitreal conbercept (IVC) or intravitreal ranibizumab (IVR) in patients with macular edema (ME) due to central retinal vein occlusion (CRVO). Methods: This retrospective study was conducted between June 2015 and January 2016 in The First Hospital of China Medical University. We administered 3 consecutive monthly doses of IVC (23 eyes) or IVR (19 eyes) in 42 eyes with CRVO-ME. At each injection, we collected aqueous humor samples and used multiplex bead assays to measure 7 angiogenic and inflammatory cytokines [vascular endothelial growth factor (VEGF), placental growth factor (PlGF), platelet-derived growth factor (PDGF)-AA, monocyte chemoattractant protein (MCP)-1, and interleukins (ILs)-6, 8, and 12]. Results: Visual acuity and ME improved significantly in both groups during the treatment period. Compared with the baseline, all the cytokine concentrations in the aqueous humor samples decreased significantly at 1 and 2 months after the initial dose of IVC or IVR. The improvement of visual acuity and ME and the changes of aqueous humor cytokine levels were similar in both groups. Concentrations of VEGF, PlGF, MCP-1, PDGF-AA, IL-6, IL-8, and IL-12 levels did not show significant intergroup differences after 1 month (P = 0.369, 0.312, 0.185, 0.353, 0.135, 0.487, and 0.337, respectively) and 2 months (P = 0.305, 0.376, 0.230, 0.519, 0.114, 0.960, and 0.830, respectively) of follow-up. Conclusion: IVC and IVR induced comparable improvements in clinical parameters, along with equivalent reductions in the concentrations of angiogenic and inflammatory cytokines in the aqueous humor.

Changes in Aqueous and Vitreous Inflammatory Cytokine Levels in Retinal Vein Occlusion: A Systematic Review and Meta-analysis

Purpose:

Evidence suggests that inflammatory cytokines not only play a role in the pathogenesis of retinal vein occlusion (RVO) but also may be useful as biomarkers to predict disease severity and response to treatment. We aimed to quantitatively summarize data on inflammatory cytokines associated with RVO.

Methods:

A systematic search of peer-reviewed English-language articles was performed without year limitation up to August 19, 2019. Studies were included if they provided data on aqueous or vitreous cytokine concentrations in patients with RVO. Data were extracted from 116 studies that encompassed 3242 study eyes with RVO and 1402 control eyes. Effect sizes were generated as standardized mean differences (SMDs) of cytokine concentrations between patients with RVO vs controls.

Results:

Among the 4644 eyes in 116 studies, aqueous and vitreous concentrations (SMD, 95% CI, and P value) of interleukin (IL)-6 (aqueous: 1.23, 0.65 to 1.81, P < .001 vitreous: 0.70, 0.49 to 0.90, P < .001), IL-8 (aqueous: 1.11, 0.73 to 1.49, P < .001; vitreous: 1.19, 0.73 to 1.65, P < .001), monocyte chemoattractant protein 1(aqueous: 1.22, 0.72 to 1.72, P < .001; vitreous 1.42, 0.92 to 1.91, P < .001), vascular endothelial growth factor (VEGF) (aqueous: 1.52, 1.09 to 1.94, P < .001; vitreous: 0.99, 0.78 to 1.21, P < .001) were significantly higher in patients with RVO than in healthy controls. Only aqueous concentrations of IL-10 (0.81, 0.45 to 1.18, P < .001), angiopoietin 4 (1.96, 0.92 to 3.00, P < .001), and platelet-derived growth factor (PDGF)-AA (0.82, 0.35 to 1.30, P < .001) were significantly higher in patients with RVO than in healthy controls. Only the vitreous concentration of soluble intercellular adhesion molecule-1 (sICAM-1) (1.23, 0.83 to 1.63, P < .001) was significantly higher in patients with RVO. No differences, failed sensitivity analyses, or insufficient data were found between patients with RVO and healthy controls for the concentrations of the remaining cytokines.

Conclusions:

Several cytokines in addition to VEGF have the potential to be useful biomarkers and therapeutic targets in RVO.