Comprehensive functional characterization of complement factor I rare variant genotypes identified in the SCOPE geographic atrophy cohort.

Rare variants (RVs) in the gene encoding the regulatory enzyme complement factor I (CFI; FI) that reduce protein function or levels increase age-related macular degeneration risk. A total of 3357 subjects underwent screening in the SCOPE natural history study for geographic atrophy secondary to age-related macular degeneration, including CFI sequencing and serum FI measurement. Eleven CFI RV genotypes that were challenging to categorize as type I (low serum level) or type II (normal serum level, reduced enzymatic function) were characterized in the context of pure FI protein in C3b and C4b fluid phase cleavage assays and a novel bead-based functional assay (BBFA) of C3b cleavage. Four variants predicted or previously characterized as benign were analyzed by BBFA for comparison. In all, three variants (W51S, C67R, and I370T) resulted in low expression. Furthermore, four variants (P64L, R339Q, G527V, and P528T) were identified as being highly deleterious with IC50s for C3b breakdown >1 log increased versus the WT protein, while two variants (K476E and R474Q) were ∼1 log reduced in function. Meanwhile, six variants (P50A, T203I, K441R, E548Q, P553S, and S570T) had IC50s similar to WT. Odds ratios and BBFA IC50s were positively correlated (r = 0.76, p < 0.01), while odds ratios versus combined annotation dependent depletion (CADD) scores were not (r = 0.43, p = 0.16). Overall, 15 CFI RVs were functionally characterized which may aid future patient stratification for complement-targeted therapies. Pure protein in vitro analysis remains the gold standard for determining the functional consequence of CFI RVs.

Retinoic acid related orphan receptor α is a genetic modifier that rescues retinal degeneration in a mouse model of Stargardt disease and Dry AMD.

Degeneration of the macula is associated with several overlapping diseases including age-related macular degeneration (AMD) and Stargardt Disease (STGD). Mutations in ATP Binding Cassette Subfamily A Member 4 (ABCA4) are associated with late-onset dry AMD and early-onset STGD. Additionally, both forms of macular degeneration exhibit deposition of subretinal material and photoreceptor degeneration. Retinoic acid related orphan receptor α (RORA) regulates the AMD inflammation pathway that includes ABCA4, CD59, C3 and C5. In this translational study, we examined the efficacy of RORA at attenuating retinal degeneration and improving the inflammatory response in Abca4 knockout (Abca4-/-) mice. AAV5-hRORA-treated mice showed reduced deposits, restored CD59 expression and attenuated amyloid precursor protein (APP) expression compared with untreated eyes. This molecular rescue correlated with statistically significant improvement in photoreceptor function. This is the first study evaluating the impact of RORA modifier gene therapy on rescuing retinal degeneration. Our studies demonstrate efficacy of RORA in improving STGD and dry AMD-like disease.

Chemokine Receptor Profile of T Cells and Progression Rate of Geographic Atrophy Secondary to Age-related Macular Degeneration.

Purpose: Geographic atrophy (GA) secondary to age-related macular degeneration is a progressive retinal degenerative disease. Systemic chemokine receptors and known risk-associated single-nucleotide polymorphisms have been associated with GA pathogenesis. Because halting progression is pivotal for patients, we investigated the association of candidate chemokine receptors and progression rate (PR) of atrophic lesions in patients with GA. Methods: This prospective observational study conducted at a single center included 85 patients with GA and 45 healthy controls. Patients were followed up after 13 months on average. Serial fundus autofluorescence images were used to determine the PR of atrophic lesions. The proportion of chemokine receptors on peripheral lymphocytes were determined by flow cytometric analysis. Results: Patients with GA had a lower proportion of CCR6 on CD8+T cells compared to healthy controls. Importantly, the proportion of CCR6 on CD4+T cells was lower in patients with fast GA progression compared to patients with slow progression of disease, suggesting that dysregulation of CCR6 could be involved in progression of GA. We also found that GA patients had a markedly higher percentage of CCR5 on CD4+ and CD8+T cells compared to healthy controls. After stratification according to ARMS2 polymorphism, we found a significantly lower level of CCR5 on CD8+T cells among patients with high-risk genotypes compared with patients with the low-risk genotype. Conclusions: Our study finds that chemokine receptors are dysregulated in patients with GA and that CCR6 might be involved in GA progression, making it a potential target for intervention.

Critical Dependence on Area in Relationship between ARMS2/HTRA1 Genotype and Faster Geographic Atrophy Enlargement: Age-Related Eye Disease Study 2 Report Number 33.

PURPOSE: To analyze ARMS2/HTRA1 as a risk factor for faster geographic atrophy (GA) enlargement according to (1) GA area and (2) contiguous enlargement versus progression to multifocality. DESIGN: Age-Related Eye Disease Study 2 (AREDS2) cohort analysis. PARTICIPANTS: Eyes with GA: 546 eyes of 406 participants. METHODS: Geographic atrophy area was measured from color fundus photographs at annual visits. Mixed-model regression of square root of GA area and proportional hazards regression of progression to multifocality were analyzed by ARMS2 genotype. MAIN OUTCOME MEASURES: Change in square root GA area and progression to multifocality. RESULTS: Geographic atrophy enlargement was significantly faster with ARMS2 risk alleles (P < 0.0001) at 0.224 mm/year (95% CI, 0.195-0.252 mm/year), 0.298 mm/year (95% CI, 0.271-0.324 mm/year), and 0.317 mm/year (95% CI, 0.279-0.355 mm/year), for 0 to 2 risk alleles, respectively. However, a significant interaction (P = 0.011) was observed between genotype and baseline area. In eyes with very small area (< 1.9 mm2), enlargement was significantly faster with ARMS2 risk alleles (P < 0.0001) at 0.193 mm/year (95% CI, 0.162-0.225 mm/year) versus 0.304 mm/year (95% CI, 0.280-0.329 mm/year) for 0 versus 1 to 2 risk alleles, respectively. With moderately small (1.9-3.8 mm2) or medium to large (≥ 3.8 mm2) area, enlargement was not significantly faster with ARMS2 risk alleles (P = 0.66 and P = 0.70, respectively). In nonmultifocal GA, enlargement was significantly faster with ARMS2 risk alleles (P = 0.001) at 0.175 mm/year (95% CI, 0.142-0.209 mm/year), 0.226 mm/year (95% CI, 0.193-0.259 mm/year), and 0.287 mm/year (95% CI, 0.237-0.337 mm/year) with 0 to 2 risk alleles, respectively. ARMS2 genotype was not associated significantly with progression to multifocal GA. CONCLUSIONS: The relationship between ARMS2/HTRA1 genotype and faster GA enlargement depends critically on GA area: risk alleles represent a strong risk factor for faster enlargement only in eyes with very small area. They increase the growth rate more through contiguous enlargement than progression to multifocality. ARMS2/HTRA1 genotype is more important in increasing risk of progression to GA and initial GA enlargement (contiguously) than in subsequent enlargement or progression to multifocality. These findings may explain some discrepancies between previous studies and have implications for both research and clinical practice. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

RPE-Directed Gene Therapy Improves Mitochondrial Function in Murine Dry AMD Models.

Age-related macular degeneration (AMD) is the most common cause of blindness in the aged population. However, to date there is no effective treatment for the dry form of the disease, representing 85-90% of cases. AMD is an immensely complex disease which affects, amongst others, both retinal pigment epithelium (RPE) and photoreceptor cells and leads to the progressive loss of central vision. Mitochondrial dysfunction in both RPE and photoreceptor cells is emerging as a key player in the disease. There are indications that during disease progression, the RPE is first impaired and RPE dysfunction in turn leads to subsequent photoreceptor cell degeneration; however, the exact sequence of events has not as yet been fully determined. We recently showed that AAV delivery of an optimised NADH-ubiquinone oxidoreductase (NDI1) gene, a nuclear-encoded complex 1 equivalent from S. cerevisiae, expressed from a general promoter, provided robust benefit in a variety of murine and cellular models of dry AMD; this was the first study employing a gene therapy to directly boost mitochondrial function, providing functional benefit in vivo. However, use of a restricted RPE-specific promoter to drive expression of the gene therapy enables exploration of the optimal target retinal cell type for dry AMD therapies. Furthermore, such restricted transgene expression could reduce potential off-target effects, possibly improving the safety profile of the therapy. Therefore, in the current study, we interrogate whether expression of the gene therapy from the RPE-specific promoter, Vitelliform macular dystrophy 2 (VMD2), might be sufficient to rescue dry AMD models.

Reticular Pseudodrusen Status, ARMS2/HTRA1 Genotype, and Geographic Atrophy Enlargement: Age-Related Eye Disease Study 2 Report 32.

PURPOSE: To determine whether reticular pseudodrusen (RPD) status, ARMS2/HTRA1 genotype, or both are associated with altered geographic atrophy (GA) enlargement rate and to analyze potential mediation of genetic effects by RPD status. DESIGN: Post hoc analysis of an Age-Related Eye Disease Study 2 cohort. PARTICIPANTS: Eyes with GA: n = 771 from 563 participants. METHODS: Geographic atrophy area was measured from fundus photographs at annual visits. Reticular pseudodrusen presence was graded from fundus autofluorescence images. Mixed-model regression of square root of GA area was performed by RPD status, ARMS2 genotype, or both. MAIN OUTCOME MEASURES: Change in square root of GA area. RESULTS: Geographic atrophy enlargement was significantly faster in eyes with RPD (P < 0.0001): 0.379 mm/year (95% confidence interval [CI], 0.329-0.430 mm/year) versus 0.273 mm/year (95% CI, 0.256-0.289 mm/year). Enlargement was also significantly faster in individuals carrying ARMS2 risk alleles (P < 0.0001): 0.224 mm/year (95% CI, 0.198-0.250 mm/year), 0.287 mm/year (95% CI, 0.263-0.310 mm/year), and 0.307 mm/year (95% CI, 0.273-0.341 mm/year) for 0, 1, and 2, respectively. In mediation analysis, the direct effect of ARMS2 genotype was 0.074 mm/year (95% CI, 0.009-0.139 mm/year), whereas the indirect effect of ARMS2 genotype via RPD status was 0.002 mm/year (95% CI, -0.006 to 0.009 mm/year). In eyes with incident GA, RPD presence was not associated with an altered likelihood of central involvement (P = 0.29) or multifocality (P = 0.16) at incidence. In eyes with incident noncentral GA, RPD presence was associated with faster GA progression to the central macula (P = 0.009): 157 µm/year (95% CI, 126-188 µm/year) versus 111 µm/year (95% CI, 97-125 µm/year). Similar findings were observed in the Age-Related Eye Disease Study. CONCLUSIONS: Geographic atrophy enlargement is faster in eyes with RPD and in individuals carrying ARMS2/HTRA1 risk alleles. However, RPD status does not mediate the association between ARMS2/HTRA1 genotype and faster enlargement. Reticular pseudodrusen presence and ARMS2/HTRA1 genotype are relatively independent risk factors, operating by distinct mechanisms. Reticular pseudodrusen presence does not predict central involvement or multifocality at GA incidence but is associated with faster progression toward the central macula. Reticular pseudodrusen status should be considered for improved predictions of enlargement rate. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Using Advanced Bioinformatics Tools to Identify Novel Therapeutic Candidates for Age-Related Macular Degeneration.

Purpose: Age-related macular degeneration (AMD) is the most common cause of aging-related blindness in the developing world. Although medications can slow progressive wet AMD, currently, no drugs to treat dry-AMD are available. We use a systems or in silico biology analysis to identify chemicals and drugs approved by the Food and Drug Administration for other indications that can be used to treat and prevent AMD. Methods: We queried National Center for Biotechnology Information to identify genes associated with AMD, wet AMD, dry AMD, intermediate AMD, and geographic atrophy to date. We combined genes from various AMD subtypes to reflect distinct stages of disease. Enrichment analysis using the ToppGene platform predicted molecules that can influence AMD genes. Compounds without clinical indications or with deleterious effects were manually filtered. Results: We identified several drug/chemical classes that can affect multiple genes involved in AMD. The drugs predicted from this analysis include antidiabetics, lipid-lowering agents, and antioxidants, which could theoretically be repurposed for AMD. Metformin was identified as the drug with the strongest association with wet AMD genes and is among the top candidates in all dry AMD subtypes. Curcumin, statins, and antioxidants are also among the top drugs correlating with AMD-risk genes. Conclusions: We use a systematic computational process to discover potential therapeutic targets for AMD. Our systematic and unbiased approach can be used to guide targeted preclinical/clinical studies for AMD and other ocular diseases. Translational Relevance: Advanced bioinformatics models identify novel chemicals and approved drug candidates that can be efficacious for different subtypes of AMD.

Lateral gain is impaired in macular degeneration and can be targeted to restore vision in mice.

Macular degeneration is a leading cause of blindness. Treatments to rescue vision are currently limited. Here, we study how loss of central vision affects lateral feedback to spared areas of the human retina. We identify a cone-driven gain control mechanism that reduces visual function beyond the atrophic area in macular degeneration. This finding provides an insight into the negative effects of geographic atrophy on vision. Therefore, we develop a strategy to restore this feedback mechanism, through activation of laterally projecting cells. This results in improved vision in Cnga3-/- mice, which lack cone function, as well as a mouse model of geographic atrophy. Our work shows that a loss of lateral gain control contributes to the vision deficit in macular degeneration. Furthermore, in mouse models we show that lateral feedback can be harnessed to improve vision following retinal degeneration.

Differential Circulating MicroRNA Expression in Age-Related Macular Degeneration.

This study explored the expression of several miRNAs reported to be deregulated in age-related macular degeneration (AMD). Total RNA was isolated from sera from patients with dry AMD (n = 12), wet AMD (n = 14), and controls (n = 10). Forty-two previously investigated miRNAs were selected based on published data and their role in AMD pathogenesis, such as angiogenic and inflammatory effects, and were co-analysed using a miRCURY LNA miRNA SYBR® Green PCR kit via quantitative real-time polymerase chain reaction (qRT-PCR) to validate their presence. Unsupervised hierarchical clustering indicated that AMD serum specimens have a different miRNA profile to healthy controls. We successfully validated the differentially regulated miRNAs in serum from AMD patients versus controls. Eight miRNAs (hsa-let-7a-5p, hsa-let-7d-5p, hsa-miR-23a-3p, hsa-miR-301a-3p, hsa-miR-361-5p, hsa-miR-27b-3p, hsa-miR-874-3p, hsa-miR-19b-1-5p) showed higher expression in the serum of dry AMD patients than wet AMD patients and compared with healthy controls. Increased quantities of certain miRNAs in the serum of AMD patients indicate that these miRNAs could potentially serve as diagnostic AMD biomarkers and might be used as future AMD treatment targets. The discovery of significant serum miRNA biomarkers in AMD patients would provide an easy screening tool for at-risk populations.

Complement Factor D as a Strategic Target for Regulating the Alternative Complement Pathway.

The complement system is central to first-line defense against invading pathogens. However, excessive complement activation and/or the loss of complement regulation contributes to the development of autoimmune diseases, systemic inflammation, and thrombosis. One of the three pathways of the complement system, the alternative complement pathway, plays a vital role in amplifying complement activation and pathway signaling. Complement factor D, a serine protease of this pathway that is required for the formation of C3 convertase, is the rate-limiting enzyme. In this review, we discuss the function of factor D within the alternative pathway and its implication in both healthy physiology and disease. Because the alternative pathway has a role in many diseases that are characterized by excessive or poorly mediated complement activation, this pathway is an enticing target for effective therapeutic intervention. Nonetheless, although the underlying disease mechanisms of many of these complement-driven diseases are quite well understood, some of the diseases have limited treatment options or no approved treatments at all. Therefore, in this review we explore factor D as a strategic target for advancing therapeutic control of pathological complement activation.

Cluster Analysis and Genotype-Phenotype Assessment of Geographic Atrophy in Age-Related Macular Degeneration: Age-Related Eye Disease Study 2 Report 25.

PURPOSE: To explore whether phenotypes in geographic atrophy (GA) secondary to age-related macular degeneration can be separated into 2 or more partially distinct subtypes and if these have different genetic associations. This is important because distinct GA subtypes associated with different genetic factors might require customized therapeutic approaches. DESIGN: Cluster analysis of participants within a controlled clinical trial, followed by assessment of phenotype-genotype associations. PARTICIPANTS: Age-Related Eye Disease Study 2 participants with incident GA during study follow-up: 598 eyes of 598 participants. METHODS: Phenotypic features from reading center grading of fundus photographs were subjected to cluster analysis, by k-means and hierarchical methods, in cross-sectional analyses (using 15 phenotypic features) and longitudinal analyses (using 14 phenotypic features). The identified clusters were compared by 4 pathway-based genetic risk scores (complement, extracellular matrix, lipid, and ARMS2). The analyses were repeated in reverse (clustering by genotype and comparison by phenotype). MAIN OUTCOME MEASURES: Characteristics and quality of cluster solutions, assessed by Calinski-Harabasz scores, unexplained variance, and consistency; and genotype-phenotype associations, assessed by t test. RESULTS: In cross-sectional phenotypic analyses, k-means identified 2 clusters (labeled A and B), whereas hierarchical clustering identified 4 clusters (C-F); cluster membership differed principally by GA configuration but in few other ways. In longitudinal phenotypic analyses, k-means identified 2 clusters (G and H) that differed principally by smoking status but in few other ways. These 3 sets of cluster divisions were not similar to each other (r ≤ 0.20). Despite adequate power, pairwise cluster comparison by the 4 genetic risk scores demonstrated no significant differences (P > 0.05 for all). In clustering by genotype, k-means identified 2 clusters (I and J). These differed principally at ARMS2, but no significant genotype-phenotype associations were observed (P > 0.05 for all). CONCLUSIONS: Phenotypic clustering resulted in GA subtypes defined principally by GA configuration in cross-sectional analyses, but these were not replicated in longitudinal analyses. These negative findings, together with the absence of significant phenotype-genotype associations, indicate that GA phenotypes may vary continuously across a spectrum, rather than consisting of distinct subtypes that arise from separate genetic causes.

Prevalence and phenotype associations of complement factor I mutations in geographic atrophy.

Rare variants in the complement factor I (CFI) gene, associated with low serum factor I (FI) levels, are strong risk factors for developing the advanced stages of age-related macular degeneration (AMD). No studies have been undertaken on the prevalence of disease-causing CFI mutations in patients with geographic atrophy (GA) secondary to AMD. A multicenter, cross-sectional, noninterventional study was undertaken to identify the prevalence of pathogenic rare CFI gene variants in an unselected cohort of patients with GA and low FI levels. A genotype-phenotype study was performed. Four hundred and sixty-eight patients with GA secondary to AMD were recruited to the study, and 19.4% (n = 91) demonstrated a low serum FI concentration (below 15.6 µg/ml). CFI gene sequencing on these patients resulted in the detection of rare CFI variants in 4.7% (n = 22) of recruited patients. The prevalence of CFI variants in patients with low serum FI levels and GA was 25%. Of the total patients recruited, 3.2% (n = 15) expressed a CFI variant classified as pathogenic or likely pathogenic. The presence of reticular pseudodrusen was detected in all patients with pathogenic CFI gene variants. Patients with pathogenic CFI gene variants and low serum FI levels might be suitable for FI supplementation in therapeutic trials.

Association of relative leukocyte telomere length and genetic variants in telomere-related genes (TERT, TERT-CLPTM1, TRF1, TNKS2, TRF2) with atrophic age-related macular degeneration.

Background: In an experimental model, telomere shortening inhibits neovascularization. It is thus possible that telomere shortening might have a role in the pathogenesis of geographic atrophy in case of age-related macular degeneration (AMD). This is why we aimed to find any associated differences of telomere length and genetic variants in telomere-related genes (TERT, TERT-CLPTM1, TRF1, TNKS2, and TRF2) in patients with atrophic AMD compared to healthy controls.Methods: The study enrolled patients with atrophic AMD (n = 56) and healthy (n = 73) controls. Samples of DNA from peripheral blood leukocytes were extracted by DNA salting-out method. The genotyping of TERT rs2736098, rs401681 in TERT-CLPTM1 locus, TRF1 rs1545827, rs10107605, TNKS2 rs10509637, rs10509639, and TRF2 rs251796 and relative leukocyte telomere length (T/S) measurement were carried out using a real-time polymerase chain reaction method. The results were assessed using the statistical analysis method of "IBM SPSS Statistics 20.0".Results: We found statistically significantly higher T/S in atrophic AMD patients than in healthy controls (T/S, median (IQR): 1.638 (1.110) vs. 0.764 (0.801), p < .001). Also, statistically significant differences were found in TRF1 rs10107605 allele (A and C) distributions between the atrophic AMD and control groups (88.36% and 11.64% vs. 95.54% and 4.46%, respectively, p = .041), as well as between the short telomere and long telomere groups (86.92% and 13.08% vs. 96.09% and 3.91%, respectively, p = .008).Conclusions: Our research revealed the leukocyte telomere length having a role in atrophic AMD development, also the association between TRF1 rs10107605 and the telomere length.

Clinical and Genetic Analysis of 63 Families Demonstrating Early and Advanced Characteristic Fundus as the Signature of CRB1 Mutations.

PURPOSE: To reveal the characteristics of ocular changes in patients with biallelic CRB1 mutations. DESIGN: Comparative exome sequencing and retrospective case series on clinical data. METHODS: Seventy-four patients from 63 families with biallelic potential pathogenic variants in CRB1 were selected from our in-house exome sequencing. The clinical data were reviewed and evaluated in detail, including best-corrected visual acuity, fundus photography, optical coherence tomography (OCT), and electroretinogram (ERG). RESULTS: Biallelic CRB1 variants, involving 45 variants including 23 novel, were identified in 40 novel families based on exome sequencing. Analyzing clinical data of the 74 individuals from 63 families revealed the following CRB1-associated phenotypes: (1) early-onset reduced visual acuity with congenital nystagmus; (2) 2 types of characteristic retinal changes including yellowish geographic macular degeneration (YMD) or nummular pigment deposits (NPD) at posterior retina with bone-spicule pigmentation at midperipheral retina; (3) undetectable rod and cone responses on ERG; (4) cystoid macular edema or macular atrophy on OCT. YMD and NPD are unique and CRB1-associated. Long-term follow-up examination as well as age- and variant-dependent phenotypic analysis suggested YMD is the early fundus change that would gradually progress to NPD. CONCLUSIONS: YMD and NPD are 2 major characteristic CRB1-associated fundus changes and the former one will advance to the latter with age. Recognizing such characteristic signs associated with biallelic CRB1 variants may be of value in areas without widespread access to genetic testing where a more targeted approach is needed and might be biomarkers for evaluation of effects for future intervention.

Genotype- and Phenotype-Based Subgroups in Geographic Atrophy Secondary to Age-Related Macular Degeneration: The EYE-RISK Consortium.

PURPOSE: Geographic atrophy (GA) secondary to age-related macular degeneration is considered a single entity. This study aimed to determine whether GA subgroups exist that can be defined by their genotype and phenotype. DESIGN: Retrospective analysis of cross-sectional data. PARTICIPANTS: Individuals (196 eyes of 196 patients) 50 years of age or older with GA from the EYE-RISK database. METHODS: Participants were graded for the presence of each of the following fundus features on color fundus photography: large soft drusen, reticular pseudodrusen (RPD), refractile drusen, hyperpigmentation, location of atrophy (foveal vs. extrafoveal), and multifocal lesions. Genotypes of 33 single nucleotide polymorphisms previously assigned to the complement, lipid metabolism, or extracellular matrix (ECM) pathways and ARMS2 also were included, and genetic risk scores (GRSs) for each of those 3 pathways were calculated. Hierarchical cluster analysis was used to determine subgroups of participants defined by these features. The discriminative ability of genotype, phenotype, or both for each subgroup was determined with 10-fold cross-validated areas under the receiver operating characteristic curve (cvAUCs), and the agreement between predicted and actual subgroup membership was assessed with calibration plots. MAIN OUTCOME MEASURES: Identification and characterization of GA subgroups based on their phenotype and genotype. RESULTS: Cluster analyses identified 3 subgroups of GA. Subgroup 1 was characterized by high complement GRS, frequently associated with large soft drusen and foveal atrophy; subgroup 2 generally showed low GRS, foveal atrophy, and few drusen (any type); and subgroup 3 showed a high ARMS2 and ECM GRS, RPD, and extrafoveal atrophy. A high discriminative ability existed between subgroups for the genotype (cvAUC, ≥0.94), and a modest discriminative ability existed for the phenotype (cvAUC, <0.65), with good calibration. CONCLUSIONS: We identified 3 GA subgroups that differed mostly by their genotype. Atrophy location and drusen type were the most relevant phenotypic features.

Chemokine Profile and the Alterations in CCR5-CCL5 Axis in Geographic Atrophy Secondary to Age-Related Macular Degeneration.

Purpose: Geographic atrophy (GA) secondary to age-related macular degeneration (AMD) is a progressive disease with no treatment option. Previous studies show chemokine-mediated recruitment of immune cells in the retina, and therefore we investigated systemic levels of chemokines and chemokine receptors in patients with GA. Methods: This observational prospective study was conducted at a single center. We included 122 participants with no immune disease: 41 participants with GA and no choroidal neovascularization, 51 patients with neovascular AMD, and 30 healthy control individuals. Flow cytometric analysis was used to detect expression level of C-C chemokine receptor (CCR)1, CCR2, CCR3, CCR5, and C-X-C motif chemokine receptor (CXCR)3 on peripheral blood mononuclear cells (CD14+ monocytes, CD4+ T cells, CD8+ T cells). Plasma levels of C-C motif ligand (CCL)11, C-X-C motif chemokine (CXCL)10, and CCL5 were measured by specific immunoassays. Enlargement rate of GA lesion was measured from autofluorescence images. Results: Participants with GA have a specific chemokine profile with a higher expression of CCR5 than healthy controls in peripheral blood mononuclear cells, and a higher plasma levels of CCL-5. Further, GA was associated with higher monocytic expression of CCR2 than in neovascular AMD. We found that a high expression level of CCR5 on CD8+ T cells was associated with slower enlargement rate of atrophic lesion. Conclusions: The study showed an association between systemic chemokine profile and GA formation. Further studies are needed to fully elucidate the possible role of systemic chemokine regulation in mediating pathogenesis of GA.

Development of a therapeutic anti-HtrA1 antibody and the identification of DKK3 as a pharmacodynamic biomarker in geographic atrophy.

Genetic polymorphisms in the region of the trimeric serine hydrolase high-temperature requirement 1 (HTRA1) are associated with increased risk of age-related macular degeneration (AMD) and disease progression, but the precise biological function of HtrA1 in the eye and its contribution to disease etiologies remain undefined. In this study, we have developed an HtrA1-blocking Fab fragment to test the therapeutic hypothesis that HtrA1 protease activity is involved in the progression of AMD. Next, we generated an activity-based small-molecule probe (ABP) to track target engagement in vivo. In addition, we used N-terminomic proteomic profiling in preclinical models to elucidate the in vivo repertoire of HtrA1-specific substrates, and identified substrates that can serve as robust pharmacodynamic biomarkers of HtrA1 activity. One of these HtrA1 substrates, Dickkopf-related protein 3 (DKK3), was successfully used as a biomarker to demonstrate the inhibition of HtrA1 activity in patients with AMD who were treated with the HtrA1-blocking Fab fragment. This pharmacodynamic biomarker provides important information on HtrA1 activity and pharmacological inhibition within the ocular compartment.