Inflammatory Factors of Macular Atrophy in Eyes With Neovascular Age-Related Macular Degeneration Treated With Aflibercept

Abstract

Background: Neovascular age-related macular degeneration (nAMD) is a leading cause of blindness in older people. Low-grade inflammation is well-known as one of the pathogenic mechanisms in nAMD. Anti-vascular endothelial growth factor (VEGF) therapy is the first-line treatment for nAMD, although macula atrophy (MA) developed under anti-VEGF therapy causes irreversible visual function impairment and is recognized as a serious disorder. Here, we show specific expression patterns of aqueous humor (AH) cytokines in nAMD eyes developing MA under intravitreal injection of aflibercept (IVA) as an anti-VEGF antibody and present predictive cytokines as biomarkers for the incidence of MA in nAMD eyes under IVA treatment.

Methods: Twenty-eight nAMD patients received three consecutive monthly IVA, followed by a pro re nata regimen for 2 years. AH specimens were collected before first IVA (pre-IVA) and before third IVA (post-IVA). AH cytokine levels, visual acuity (VA), and central retinal thickness (CRT) were measured.

Results: Two-year incidence of MA was 21.4%. In nAMD eyes developing MA [MA (+) group], pre-IVA levels of monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1β, VEGF and post-IVA level of MCP-1 were higher than those in nAMD eyes without MA [MA (-) group]. In hierarchical cluster analysis, pre-IVA MCP-1 and VEGF were grouped into the same subcluster, as were post-IVA MCP-1 and CRT. In principal component analysis, principal component loading (PCL) of pre-IVA interferon-γ-inducible protein 10 (IP-10) was 0.61, but PCL of post-IVA IP-10 decreased to -0.09. In receiver operating characteristic analysis and Kaplan-Meier curves, pre-IVA MCP-1, MIP-1β, and VEGF and post-IVA interleukin-6, MCP-1, and MIP-1β were detected as predictive factors for MA incidence. In 2-year clinical course, changes of VA in groups with high levels of pre-IVA MIP-1β (over 39.9 pg/ml) and VEGF (over 150.4 pg/ml) were comparable to those in MA (+) group.

Conclusion: Substantial loss of IP-10 effects and persistent inflammation contribute to incidence of MA, and screening of AH cytokine levels could be a useful method to predict MA incidence in nAMD eyes under anti-VEGF therapy.

Keywords: aflibercept; aqueous humor cytokine; interferon-γ-inducible protein 10; macrophage inflammatory protein-1β; macular atrophy; monocyte chemoattractant protein-1; neovascular age-related macular degeneration; vascular endothelial growth factor.

Figure 1

Trial profile. Flowchart of treatment-naive nAMD patients enrolled for IVA treatment is shown. Finally, 28 patients were eligible for analysis in this study. *One patient with branch retinal vein occlusion, one with central serous chorioretinopathy, and one with diabetic macular edema. ^#One had vitrectomy for epiretinal membrane, and one had scleral buckling for rhegmatogenous retinal detachment. AH, aqueous humor; CRT, central retinal thickness; IOL, intraocular lens; IVA, intravitreal injection of aflibercept; LPI, laser peripheral iridotomy; nAMD, neovascular age-related macular degeneration.

Figure 2

Hierarchical cluster analysis for the variables of visual acuity, central macula thickness, and aqueous humor cytokines in nAMD eyes with or without incidence of macular atrophy under aflibercept treatment. Heat maps of logMAR VA, CRT, and AH cytokines in (A) MA (+) group pre-IVA, (B) MA (−) group pre-IVA, (C) MA (+) group post-IVA, and (D) MA (−) group post-IVA are shown. Color scale: low values, red; middle to high values, black to green. Vertical axis shows subtypes of nAMD, and horizontal axis demonstrates logMAR VA, CRT, and aqueous humor cytokines. AH, aqueous humor; CRT, central retinal thickness; IVA, intravitreal injection of aflibercept; MA, macular atrophy; MA (+) group, nAMD eyes developing MA; MA (−) group, nAMD eyes without MA; logMAR, logarithm of the minimum angle of resolution; nAMD, neovascular age-related macular degeneration; VA, visual acuity.

Figure 3

Expression patterns of visual acuity, central macula thickness, and aqueous humor cytokines by principal component analysis in nAMD eyes with or without development of macular atrophy under aflibercept treatment. Biplots of PCLs in PC1 and PC2 of (A) MA (+) group pre-IVA, (B) MA (−) group pre-IVA, (C) MA (+) group post-IVA, and (D) MA (−) group post-IVA are shown. Eigenvalues, CR, and CCR of PC1 and PC2 are presented in (E) MA (+) group and MA (−) group pre-IVA and (F) MA (+) group and MA (−) group post-IVA. CCR, cumulative contribution ratio; CR, contribution ratio; IVA, intravitreal injection of aflibercept; MA, macular atrophy; nAMD, neovascular age-related macular degeneration; PC, principal component; PCL, principal component loading; PC1, first principal component; PC2, second principal component.

Figure 4

Predictive factors for the incidence of macular atrophy in nAMD eyes under aflibercept treatment. (A) ROC curves of age, pre-IVA logMAR VA, and pre-IVA levels of MCP-1, MIP-1β, and VEGF are shown as predictive factors for MA incidence in nAMD eyes under IVA treatment for 2 years. (B) ROC curves of post-IVA logMAR VA and post-IVA levels of IL-6, MCP-1, and MIP-1β are presented. Cutoff value is defined by closest point to upper left-hand corner of graph. IL, interleukin; IVA, intravitreal injection of aflibercept; MA, macular atrophy; logMAR, logarithm of the minimum angle of resolution; MCP-1, monocyte chemotactic protein-1; MIP-1β, macrophage inflammatory protein; nAMD, neovascular age-related macular degeneration; ROC, receiver operating characteristic; VEGF, vascular endothelial growth factor.

Figure 5

Probability of incidence of macular atrophy depending on age, visual acuity, and aqueous humor cytokine levels in nAMD eyes under aflibercept treatment. Kaplan–Meier survival curves were used to estimate the probability of MA incidence in nAMD eyes under IVA treatment for 2 years. The nAMD group was divided by cutoff values: (A) age over or under 75 years at baseline, (B) pre-IVA logMAR VA higher or lower than 0.824, (C) pre-IVA level of MCP-1 higher or lower than 120.8 pg/ml, (D) pre-IVA level of MIP-1β higher or lower than 39.9 pg/ml, (E) pre-IVA level of VEGF higher or lower than 150.4 pg/ml, (F) post-IVA logMAR VA higher or lower than 0.301, and (G) post-IVA level of IL-6 higher or lower than 7.01 pg/ml. (H) Values of chi-square and p between high-value and low-value groups divided by each cutoff value. (I) Rates of MA incidence in high-value and low-value groups divided by each cutoff value. *percentage; IL, interleukin; IVA, intravitreal injection of aflibercept; MA, macular atrophy; logMAR, logarithm of the minimum angle of resolution; MCP-1, monocyte chemotactic protein-1; MIP-1β, macrophage inflammatory protein; mon., month; nAMD, neovascular age-related macular degeneration; VA, visual acuity; VEGF, vascular endothelial growth factor.

Figure 6

Two-year clinical courses of visual acuity and central macula thickness in nAMD group divided by the presence of macular atrophy, visual acuity, or levels of aqueous humor cytokines. Two-year clinical courses of (a) logMAR VA and (b) CRT in nAMD eyes under IVA treatment for 2 years, classified by (A) presence or absence of MA incidence and above or below cutoff values of (B) pre-IVA logMAR VA, (C) pre-IVA level of MCP-1, (D) pre-IVA level of MIP-1β, (E) pre-IVA level of VEGF, and (F) post-IVA logMAR VA are shown. The cutoff values were the same as those used in Kaplan–Meier curves (). Data are expressed in mean (close circle) and standard deviation (error bar). CRT, central retinal thickness; IVA, intravitreal injection of aflibercept; MA, macular atrophy; logMAR, logarithm of the minimum angle of resolution; MCP-1, monocyte chemotactic protein-1; MIP-1β, macrophage inflammatory protein; nAMD, neovascular age-related macular degeneration; VA, visual acuity; VEGF, vascular endothelial growth factor.