Complement C3 variant and the risk of age-related macular degeneration

Clinical Characteristics and Progression of Pachychoroid and Conventional Geographic Atrophy

Purpose

To elucidate the clinical characteristics and progression rates of pachychoroid and conventional geographic atrophy (GA).

Design

Retrospective, multicenter, observational study.

Participants

A total of 173 eyes from 173 patients (38 eyes with pachychoroid GA and 135 with conventional GA) from 6 university hospitals in Japan were included. All patients were Japanese, aged ≥50 years and with fundus autofluorescence images having analyzable image quality. A total of 101 eyes (22 with pachychoroid GA and 79 with conventional GA) were included in the follow-up group.

Methods

The studied eyes were classified as having pachychoroid or conventional GA; the former was diagnosed if the eye had features of pachychoroid and no drusen. The GA area was semiautomatically measured on fundus autofluorescence images, and the GA progression rate was calculated for the follow-up group. Multivariable linear regression analysis was used to determine whether the rate of GA progression was associated with GA subtype.

Main Outcome Measures

Clinical characteristics and progression rates of pachychoroid and conventional GA.

Results

The pachychoroid GA group was significantly younger (70.3 vs. 78.7 years; P < 0.001), more male-dominant (89.5 vs. 55.6%; P < 0.001), and had better best-corrected visual acuity (0.15 vs. 0.40 in logarithm of the minimum angle of resolution; P = 0.002), thicker choroid (312.4 vs. 161.6 μm; P < 0.001), higher rate of unifocal GA type (94.7 vs. 49.6%; P < 0.001), and smaller GA area (0.59 vs. 3.76 mm2;P < 0.001) than the conventional GA group. In the follow-up group, the mean GA progression rate (square-root transformation) was significantly lower in the pachychoroid GA group than in the conventional GA group (0.11 vs. 0.27 mm/year; P < 0.001).

Conclusions

Demographic and ocular characteristics differed between GA subtypes. The progression rate of pachychoroid GA, adjusted for age and baseline GA area, was significantly lower than that of conventional GA. Japanese patients with conventional GA showed characteristics and progression rates similar to those in White populations. Some characteristics of GA in Japanese population differ from those in Waucasian populations, which may be due to the inclusion of pachychoroid GA.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Natural History of Visual Acuity and Microperimetry-Based Functional Outcome Measures of the Macula in Patients with Geographic Atrophy: A Retrospective Chart Review Study in Germany

Background/Objectives: Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD) leading to the progressive and irreversible loss of visual function. Characteristics of GA include atrophic lesions resulting from the loss of photoreceptors, retinal pigment epithelium, and choriocapillaris. During GA progression, atrophic lesions typically advance from the macular periphery to the center, affecting foveal light sensitivity and visual acuity. This study analyzed changes in light sensitivity and visual acuity during the natural course of GA progression using the topographic analysis of structural and functional changes based on Early Treatment Diabetic Retinopathy Study (ETDRS) charts, multimodal imaging, and microperimetry assessment. Methods: Medical chart data of GA patients between 2014 and 2022 from the Internationale Innovative Ophthalmochirurgie GbR (I.I.O.) research center (Düsseldorf, Germany) were retrospectively analyzed. All patient eyes fulfilling the phase 3 OAKS study inclusion criteria were included and followed up for 60 months. The imputation of missing measurements and dropouts was performed by linear mixed models. Results: A total of 20 GA eyes from 13 GA patients were included in the study. At the index, 53.8% of patients had bilateral GA, with 70.0% of the eyes showing multifocal GA and 30.0% subfoveal encroachment (SFE). A total of 35.0% of the eyes had 2-5, and 15.0% over 20, areas of atrophy. Over time, the GA lesion size increased from 6.4 mm2 to 11.8 mm2 (1.08 mm2/year). After an average observation time of 2.9 years, 78.6% of the initially unaffected study eyes developed SFE. The percentage of study eyes without visual impairment decreased from 55.0% to 30.0%, with mean normal-luminance best-corrected visual acuity (NL-BCVA) reducing from 63.7 to 55.7 ETDRS letters. The share of absolute scotoma points in microperimetry assessment increased from 15.7% to 43.5% while overall average macular sensitivity declined from 15.7 dB to 7.4 dB. Conclusions: The substantial deterioration of macular outcomes and visual function was comprehensively detected. The results were a documentation of structural and functional aspects of the natural progression of GA for a 60-month follow-up, providing a typical outline for AMD patients with GA.

Genetic Insights into Age-Related Macular Degeneration

One of the major causes of vision impairment among elderly people in developed nations is age-related macular degeneration (AMD). The distinctive features of AMD are the accumulation of extracellular deposits called drusen and the gradual deterioration of photoreceptors and nearby tissues in the macula. AMD is a complex and multifaceted disease influenced by several factors such as aging, environmental risk factors, and a person's genetic susceptibility to the condition. The interaction among these factors leads to the initiation and advancement of AMD, where genetic predisposition plays a crucial role. With the advent of high-throughput genotyping technologies, many novel genetic loci associated with AMD have been identified, enhancing our knowledge of its genetic architecture. The common genetic variants linked to AMD are found on chromosome 1q32 (in the complement factor H gene) and 10q26 (age-related maculopathy susceptibility 2 and high-temperature requirement A serine peptidase 1 genes) loci, along with several other risk variants. This review summarizes the common genetic variants of complement pathways, lipid metabolism, and extracellular matrix proteins associated with AMD risk, highlighting the intricate pathways contributing to AMD pathogenesis. Knowledge of the genetic underpinnings of AMD will allow for the future development of personalized diagnostics and targeted therapeutic interventions, paving the way for more effective management of AMD and improved outcomes for affected individuals.

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.

Immunogenetic and Environmental Factors in Age-Related Macular Disease

Age-related macular degeneration (AMD) is a chronic disease, which often develops in older people, but this is not the rule. AMD pathogenesis changes include the anatomical and functional complex. As a result of damage, it occurs, in the retina and macula, among other areas. These changes may lead to partial or total loss of vision. This disease can occur in two clinical forms, i.e., dry (progression is slowly and gradually) and exudative (wet, progression is acute and severe), which usually started as dry form. A coexistence of both forms is possible. AMD etiology is not fully understood. Extensive genetic studies have shown that this disease is multifactorial and that genetic determinants, along with environmental and metabolic-functional factors, are important risk factors. This article reviews the impact of heavy metals, macro- and microelements, and genetic factors on the development of AMD. We present the current state of knowledge about the influence of environmental factors and genetic determinants on the progression of AMD in the confrontation with our own research conducted on the Polish population from Kuyavian-Pomeranian and Lubusz Regions. Our research is concentrated on showing how polluted environments of large agglomerations affects the development of AMD. In addition to confirming heavy metal accumulation, the growth of risk of acute phase factors and polymorphism in the genetic material in AMD development, it will also help in the detection of new markers of this disease. This will lead to a better understanding of the etiology of AMD and will help to establish prevention and early treatment.

Complement regulation in the eye: implications for age-related macular degeneration

Careful regulation of the complement system is critical for enabling complement proteins to titrate immune defense while also preventing collateral tissue damage from poorly controlled inflammation. In the eye, this balance between complement activity and inhibition is crucial, as a low level of basal complement activity is necessary to support ocular immune privilege, a prerequisite for maintaining vision. Dysregulated complement activation contributes to parainflammation, a low level of inflammation triggered by cellular damage that functions to reestablish homeostasis, or outright inflammation that disrupts the visual axis. Complement dysregulation has been implicated in many ocular diseases, including glaucoma, diabetic retinopathy, and age-related macular degeneration (AMD). In the last two decades, complement activity has been the focus of intense investigation in AMD pathogenesis, leading to the development of novel therapeutics for the treatment of atrophic AMD. This Review outlines recent advances and challenges, highlighting therapeutic approaches that have advanced to clinical trials, as well as providing a general overview of the complement system in the posterior segment of the eye and selected ocular diseases.

The Role of Glutathione in Age-Related Macular Degeneration (AMD)

Age-related macular degeneration (AMD) is a chronic disease that usually develops in older people. Pathogenetic changes in this disease include anatomical and functional complexes. Harmful factors damage the retina and macula. These changes may lead to partial or total loss of vision. The disease can occur in two clinical forms: dry (the progression is slow and gentle) and exudative (wet-progression is acute and severe), which usually starts in the dry form; however, the coexistence of both forms is possible. The etiology of AMD is not fully understood, and the precise mechanisms of the development of this illness are still unknown. Extensive genetic studies have shown that AMD is a multi-factorial disease and that genetic determinants, along with external and internal environmental and metabolic-functional factors, are important risk factors. This article reviews the role of glutathione (GSH) enzymes engaged in maintaining the reduced form and polymorphism in glutathione S-transferase theta-1 (GSTT1) and glutathione S-transferase mu-1 (GSTM1) in the development of AMD. We only chose papers that confirmed the influence of the parameters on the development of AMD. Because GSH is the most important antioxidant in the eye, it is important to know the influence of the enzymes and genetic background to ensure an optimal level of glutathione concentration. Numerous studies have been conducted on how the glutathione system works till today. This paper presents the current state of knowledge about the changes in GSH, GST, GR, and GPx in AMD. GST studies clearly show increased activity in ill people, but for GPx, the results relating to activity are not so clear. Depending on the research, the results also suggest higher and lower GPx activity in patients with AMD. The analysis of polymorphisms in GST genes confirmed that mutations lead to weaker antioxidant barriers and may contribute to the development of AMD; unfortunately, a meta-analysis and some research did not confirm that connection. Unspecific results of many of the parameters that make up the glutathione system show many unknowns. It is so important to conduct further research to understand the exact mechanism of defense functions of glutathione against oxidative stress in the human eye.

Potential Causal Association between C-Reactive Protein Levels in Age-Related Macular Degeneration: A Two-Sample Mendelian Randomization Study

Researchers have proposed a possible correlation between age-related macular degeneration (AMD) and inflammation or C-reactive protein (CRP) levels. We investigated the potential causal relationship between CRP levels and AMD. Single-nucleotide polymorphisms (SNPs) associated with CRP exposure were selected as the instrumental variables (IVs) with significance (p < 5 × 10-8) from the genome-wide association study (GWAS) meta-analysis data of Biobank Japan and the UK Biobank. GWAS data for AMD were obtained from 11 International AMD Genomics Consortium studies. An evaluation of causal estimates, utilizing the inverse-variance-weighted (IVW), weighted-median, MR-Egger, MR-Pleiotropy-Residual-Sum, and Outlier tests, was conducted in a two-sample Mendelian randomization (MR) study. We observed significant causal associations between CRP levels and AMD (odds ratio [OR] = 1.13, 95% CI = [1.02-1.24], and p = 0.014 in IVW; OR = 1.18, 95% CI = [1.00-1.38], and p = 0.044 in weight median; OR = 1.31, 95% CI = [1.13-1.52], and p < 0.001 in MR-Egger). The causal relationship between CRP and AMD warrants further research to address the significance of inflammation as a risk factor for AMD.

The contribution of pattern recognition receptor signalling in the development of age related macular degeneration: the role of toll-like-receptors and the NLRP3-inflammasome

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss, characterised by the dysfunction and death of the photoreceptors and retinal pigment epithelium (RPE). Innate immune cell activation and accompanying para-inflammation have been suggested to contribute to the pathogenesis of AMD, although the exact mechanism(s) and signalling pathways remain elusive. Pattern recognition receptors (PRRs) are essential activators of the innate immune system and drivers of para-inflammation. Of these PRRs, the two most prominent are (1) Toll-like receptors (TLR) and (2) NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3)-inflammasome have been found to modulate the progression of AMD. Mutations in TLR2 have been found to be associated with an increased risk of developing AMD. In animal models of AMD, inhibition of TLR and NLRP3 has been shown to reduce RPE cell death, inflammation and angiogenesis signalling, offering potential novel treatments for advanced AMD. Here, we examine the evidence for PRRs, TLRs2/3/4, and NLRP3-inflammasome pathways in macular degeneration pathogenesis.

The Association Between Metformin Use and New-Onset ICD Coding of Geographic Atrophy

Purpose

Metformin has been suggested to protect against the development of age-related macular degeneration (AMD) in multiple observational studies. However, the association between metformin and geographic atrophy (GA), a debilitating subtype of AMD, has not been analyzed.

Methods

We conducted a case-control study of patients ages 60 years and older with new-onset International Classification of Diseases (ICD) coding of GA in the Merative MarketScan Commercial and Medicare Databases between 2017 and 2021. Cases were matched with propensity scores estimated by age, region, hypertension, and Charlson Comorbidity Index to a control without GA of the same year. Exposure to metformin was assessed for cases and controls in the year prior to their index visit. Conditional multivariable logistic regression, adjusting for AMD risk factors, was used to calculate odd ratios and 95% confidence intervals (CIs). This study design and analysis were repeated in a sample of patients without diabetes.

Results

In the full sample, we identified 10,505 cases with GA and 10,502 matched controls without GA. In total, 1149 (10.9%) cases and 1277 (12.2%) controls were exposed to metformin, and in multivariable regression, metformin decreased the odds of new-onset ICD coding of GA by 12% (95% CI, 0.79-0.99). In the sample of patients without diabetes, we identified 7611 cases with GA and 7608 matched controls without GA. Twenty-nine (0.4%) cases and 63 (0.8%) controls were exposed to metformin, and in multivariable regression, metformin decreased the odds of new-onset ICD coding of GA by 47% (95% CI, 0.33-0.83).

Conclusions

Metformin may hold promise as a noninvasive, alternative agent to prevent the development of GA. This finding is notable due to shortcomings in recently approved therapeutics for GA and metformin's overall ease of use and few adverse effects. Additional studies are required to explore our findings further and motivate a clinical trial.

Gliosis-dependent expression of complement factor H truncated variants attenuates retinal neurodegeneration following ischemic injury

Inherited, age-related, and acute retinal diseases are often exacerbated by an aberrant or excessive activity of the complement system. Consequently, cells not directly affected by an acute event or genetic variants may degenerate, resulting in enhanced visual impairment. The therapeutic potential of supplementation of complement factor H (FH), a key regulator of the complement cascade, is therefore particularly promising in the context of retinal diseases caused by complement activation. In this study, we engineered adeno-associated viruses (AAVs) containing sequences of two truncated human FH variants. The expression of these variants was regulated by the glial fibrillary acidic protein (GFAP) promoter, which is selectively active in gliotic Müller cells. Both FH variants consisted of FH domains 19-20, which were connected to domains 1-4 and 1-7, respectively, by a polyglycine linker. These AAVs were intravitreally injected following ischemic injury of C57BL/6J mouse retinas. We observed transgene expression in gliotic Müller cells and to some extent in astrocytes. The expression correlated directly with damage severity. Interventions resulted in decreased complement activation, accelerated normalization of microglia activity and morphological improvements. Reduced levels of C3 transcripts and C3d protein in conjunction with higher transcript levels of inhibitory regulators like Cfi and Cfh, hinted at attenuated complement activity. This study demonstrates the great potential of complement regulatory gene addition therapy. With further in vivo testing it could be applied to treat a wide range of retinal diseases where no causative therapies are available.

The Role of Complement Dysregulation in Glaucoma

Glaucoma is a progressive neurodegenerative disease characterized by damage to the optic nerve that results in irreversible vision loss. While the exact pathology of glaucoma is not well understood, emerging evidence suggests that dysregulation of the complement system, a key component of innate immunity, plays a crucial role. In glaucoma, dysregulation of the complement cascade and impaired regulation of complement factors contribute to chronic inflammation and neurodegeneration. Complement components such as C1Q, C3, and the membrane attack complex have been implicated in glaucomatous neuroinflammation and retinal ganglion cell death. This review will provide a summary of human and experimental studies that document the dysregulation of the complement system observed in glaucoma patients and animal models of glaucoma driving chronic inflammation and neurodegeneration. Understanding how complement-mediated damage contributes to glaucoma will provide opportunities for new therapies.

The role of the retinal vasculature in age-related macular degeneration: a spotlight on OCTA

Age-related macular degeneration (AMD) remains a disease with high morbidity and an incompletely understood pathophysiological mechanism. The ocular blood supply has been implicated in the development of the disease process, of which most research has focused on the role of the choroid and choriocapillaris. Recently, interest has developed into the role of the retinal vasculature in AMD, particularly with the advent of optical coherence tomography angiography (OCTA), which enables non-invasive imaging of the eye's blood vessels. This review summarises the up-to-date body of work in this field including the proposed links between observed changes in the retinal vessels and the development of AMD and potential future directions for research in this area. The review highlights that the strongest evidence supports the observation that patients with early to intermediate AMD have reduced vessel density in the superficial vascular complex of the retina, but also emphasises the need for caution when interpreting such studies due to their variable methodologies and nomenclature.

CRISPR Manipulation of Age-Related Macular Degeneration Haplotypes in the Complement System: Potential Future Therapeutic Applications/Avenues

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss among the elderly in the developed world. Whilst AMD is a multifactorial disease, the involvement of the complement system in its pathology is well documented, with single-nucleotide polymorphisms (SNPs) in different complement genes representing an increased risk factor. With several complement inhibitors explored in clinical trials showing limited success, patients with AMD are still without a reliable treatment option. This indicates that there is still a gap of knowledge in the functional implications and manipulation of the complement system in AMD, hindering the progress towards translational treatments. Since the discovery of the CRISPR/Cas system and its development into a powerful genome engineering tool, the field of molecular biology has been revolutionised. Genetic variants in the complement system have long been associated with an increased risk of AMD, and a variety of haplotypes have been identified to be predisposing/protective, with variation in complement genes believed to be the trigger for dysregulation of the cascade leading to inflammation. AMD-haplotypes (SNPs) alter specific aspects of the activation and regulation of the complement cascade, providing valuable insights into the pathogenic mechanisms of AMD with important diagnostic and therapeutic implications. The effect of targeting these AMD-related SNPs on the regulation of the complement cascade has been poorly explored, and the CRISPR/Cas system provides an ideal tool with which to explore this avenue. Current research concentrates on the association events of specific AMD-related SNPs in complement genes without looking into the effect of targeting these SNPs and therefore influencing the complement system in AMD pathogenesis. This review will explore the current understanding of manipulating the complement system in AMD pathogenesis utilising the genomic manipulation powers of the CRISPR/Cas systems. A number of AMD-related SNPs in different complement factor genes will be explored, with a particular emphasis on factor H (CFH), factor B (CFB), and complement C3 (C3).

The Relationship between Complements and Age-Related Macular Degeneration and Its Pathogenesis

Age-related macular degeneration is a retinal disease that causes permanent loss of central vision in people over the age of 65. Its pathogenesis may be related to mitochondrial dysfunction, inflammation, apoptosis, autophagy, complement, intestinal flora, and lipid disorders. In addition, the patient's genes, age, gender, cardiovascular disease, unhealthy diet, and living habits may also be risk factors for this disease. Complement proteins are widely distributed in serum and tissue fluid. In the early 21st century, a connection was found between the complement cascade and age-related macular degeneration. However, little is known about the effect of complement factors on the pathogenesis of age-related macular degeneration. This article reviews the factors associated with age-related macular degeneration, the relationship between each factor and complement, the related functions, and variants and provides new ideas for the treatment of this disease.

Retinal Vasculitis After Intravitreal Pegcetacoplan: Report From the ASRS Research and Safety in Therapeutics (ReST) Committee

Purpose: To analyze post-marketing cases of retinal vasculitis after intravitreal pegcetacoplan. Methods: The American Society of Retina Specialists (ASRS) Research and Safety in Therapeutics (ReST) Committee as well as an expert panel performed a retrospective review of cases of retinal vasculitis reported to the ASRS. Clinical and imaging characteristics were reviewed for evidence of retinal vasculitis and analyzed. Results: Fourteen eyes of 13 patients were confirmed to have retinal vasculitis by review of imaging studies. All cases occurred after the first pegcetacoplan injection. Occlusive retinal vasculopathy was confirmed in 11 eyes (79%). Patients presented a median of 10.5 days (range, 8-23 days) after pegcetacoplan injection. All eyes had anterior chamber inflammation, and 12 eyes (86%) had vitritis. Vasculopathy involved retinal veins (100%) more than arteries (73%), and 12 eyes (86%) had retinal hemorrhages. The median visual acuity (VA) was 20/60 (range, 20/30-5/200) at baseline, 20/300 (range, 20/100-no light perception [NLP]) at vasculitis presentation, and 20/200 (range 20/70-NLP) at the last follow-up. Eight eyes (57%) had more than a 3-line decrease in VA, and 6 eyes (43%) had more than a 6-line decrease in VA from baseline to the final follow-up, including 2 eyes that were enucleated. Six eyes (43%) developed signs of anterior segment neovascularization. Conclusions: There is currently no known etiology for vasculitis in this series. Optimum treatment strategies remain unknown. Infectious etiologies should be considered, and corticosteroid treatments may hasten resolution of inflammatory findings. Continued treatment of affected patients with pegcetacoplan should be avoided.

Treatment of geographic atrophy: an update on data related to pegcetacoplan

PURPOSE OF REVIEW

Geographic atrophy is an advanced and currently untreatable form of age-related macular degeneration (AMD), which leads to significant compromise of visual function and quality of life. Dysregulation of the complement cascade has been directly implicated in AMD pathogenesis. Pegcetacoplan is a pegylated highly selective bicyclic peptide that inhibits the cleavage of complement component 3 (C3), which represents a key step in propagation of the complement cascade. The phase 2 FILLY trial as well as the phase 3 OAKS and DERBY trials have evaluated the safety and efficacy of pegcetacoplan for the treatment of GA.

RECENT FINDINGS

The FILLY, OAKS and DERBY trials have demonstrated that local inhibition of C3 cleavage with pegcetacoplan can reduce geographic atrophy lesion growth compared with sham with an effect size of approximately 11-35% depending on the specific trial and specific geographic atrophy phenotype considered. Overall pegcetacoplan has appeared to be well tolerated with the notable side effect of a dose-dependent increase in the rate of exudative AMD development in treated eyes.

SUMMARY

The FILLY, OAKS and DERBY trials have demonstrated that pegcetacoplan is a potentially viable treatment for geographic atrophy. Additional data from the 2-year outcomes of DERBY and OAKS as well as data from the ongoing 3-year GALE extension study will provide additional insights into the potential therapeutic benefit of pegcetacoplan. Future studies assessing complement inhibition at earlier stages of AMD, with the goal of preventing geographic atrophy formation, are warranted.

Recent Developments in Gene Therapy for Neovascular Age-Related Macular Degeneration: A Review

Age-related macular degeneration (AMD) is a complex and multifactorial disease and a leading cause of irreversible blindness in the elderly population. The anti-vascular endothelial growth factor (anti-VEGF) therapy has revolutionized the management and prognosis of neovascular AMD (nAMD) and is currently the standard of care for this disease. However, patients are required to receive repeated injections, imposing substantial social and economic burdens. The implementation of gene therapy methods to achieve sustained delivery of various therapeutic proteins holds the promise of a single treatment that could ameliorate the treatment challenges associated with chronic intravitreal therapy, and potentially improve visual outcomes. Several early-phase trials are currently underway, evaluating the safety and efficacy of gene therapy for nAMD; however, areas of controversy persist, including the therapeutic target, route of administration, and potential safety issues. In this review, we assess the evolution of gene therapy for nAMD and summarize several preclinical and early-stage clinical trials, exploring challenges and future directions.

CCR1 mediates Müller cell activation and photoreceptor cell death in macular and retinal degeneration

Mononuclear cells are involved in the pathogenesis of retinal diseases, including age-related macular degeneration (AMD). Here, we examined the mechanisms that underlie macrophage-driven retinal cell death. Monocytes were extracted from patients with AMD and differentiated into macrophages (hMdɸs), which were characterized based on proteomics, gene expression, and ex vivo and in vivo properties. Using bioinformatics, we identified the signaling pathway involved in macrophage-driven retinal cell death, and we assessed the therapeutic potential of targeting this pathway. We found that M2a hMdɸs were associated with retinal cell death in retinal explants and following adoptive transfer in a photic injury model. Moreover, M2a hMdɸs express several CCRI (C-C chemokine receptor type 1) ligands. Importantly, CCR1 was upregulated in Müller cells in models of retinal injury and aging, and CCR1 expression was correlated with retinal damage. Lastly, inhibiting CCR1 reduced photic-induced retinal damage, photoreceptor cell apoptosis, and retinal inflammation. These data suggest that hMdɸs, CCR1, and Müller cells work together to drive retinal and macular degeneration, suggesting that CCR1 may serve as a target for treating these sight-threatening conditions.

NR4A1 deletion promotes pro-angiogenic polarization of macrophages derived from classical monocytes in a mouse model of neovascular age-related macular degeneration

BACKGROUND

Neovascular age-related macular degeneration causes vision loss from destructive angiogenesis, termed choroidal neovascularization (CNV). Cx3cr1-/- mice display alterations in non-classical monocytes and microglia with increased CNV size, suggesting that non-classical monocytes may inhibit CNV formation. NR4A1 is a transcription factor that is necessary for maturation of non-classical monocytes from classical monocytes. While Nr4a1-/- mice are deficient in non-classical monocytes, results are confounded by macrophage hyper-activation. Nr4a1se2/se2 mice lack a transcriptional activator, resulting in non-classical monocyte loss without macrophage hyper-activation.

MAIN BODY

We subjected Nr4a1-/- and Nr4a1se2/se2 mice to the laser-induced CNV model and performed multi-parameter flow cytometry. We found that both models lack non-classical monocytes, but only Nr4a1-/- mice displayed increased CNV area. Additionally, CD11c+ macrophages were increased in Nr4a1-/- mice. Single-cell transcriptomic analysis uncovered that CD11c+ macrophages were enriched from Nr4a1-/- mice and expressed a pro-angiogenic transcriptomic profile that was disparate from prior reports of macrophage hyper-activation.

CONCLUSIONS

These results suggest that non-classical monocytes are dispensable during CNV, and NR4A1 deficiency results in increased recruitment of pro-angiogenic macrophages.

Nucleocytoplasmic transport at the crossroads of proteostasis, neurodegeneration and neuroprotection

Nucleocytoplasmic transport comprises the multistep assembly, transport, and disassembly of protein and RNA cargoes entering and exiting nuclear pores. Accruing evidence supports that impairments to nucleocytoplasmic transport are a hallmark of neurodegenerative diseases. These impairments cause dysregulations in nucleocytoplasmic partitioning and proteostasis of nuclear transport receptors and client substrates that promote intracellular deposits - another hallmark of neurodegeneration. Disturbances in liquid-liquid phase separation (LLPS) between dense and dilute phases of biomolecules implicated in nucleocytoplasmic transport promote micrometer-scale coacervates, leading to proteinaceous aggregates. This Review provides historical and emerging principles of LLPS at the interface of nucleocytoplasmic transport, proteostasis, aging and noxious insults, whose dysregulations promote intracellular aggregates. E3 SUMO-protein ligase Ranbp2 constitutes the cytoplasmic filaments of nuclear pores, where it acts as a molecular hub for rate-limiting steps of nucleocytoplasmic transport. A vignette is provided on the roles of Ranbp2 in nucleocytoplasmic transport and at the intersection of proteostasis in the survival of photoreceptor and motor neurons under homeostatic and pathophysiological environments. Current unmet clinical needs are highlighted, including therapeutics aiming to manipulate aggregation-dissolution models of purported neurotoxicity in neurodegeneration.

Complement factor I: Regulatory nexus, driver of immunopathology, and therapeutic

Complement factor I (FI) is the nexus for classical, lectin and alternative pathway complement regulation. FI is an 88 kDa plasma protein that circulates in an inactive configuration until it forms a trimolecular complex with its cofactor and substrate whereupon a structural reorganization allows the catalytic triad to cleave its substrates, C3b and C4b. In keeping with its role as the master complement regulatory enzyme, deficiency has been linked to immunopathology. In the setting of complete FI deficiency, a consumptive C3 deficiency results in recurrent infections with encapsulated microorganisms. Aseptic cerebral inflammation and vasculitic presentations are also less commonly observed. Heterozygous mutations in the factor I gene (CFI) have been demonstrated to be enriched in atypical haemolytic uraemic syndrome, albeit with a very low penetrance. Haploinsufficiency of CFI has also been associated with decreased retinal thickness and is a strong risk factor for the development of age-related macular degeneration. Supplementation of FI using plasma purified or recombinant protein has long been postulated, however, technical difficulties prevented progression into clinical trials. It is only using gene therapy that CFI supplementation has reached the clinic with GT005 in phase I/II clinical trials for geographic atrophy.

Ocular Vascular Diseases: From Retinal Immune Privilege to Inflammation

The eye is an immune privileged tissue that insulates the visual system from local and systemic immune provocation to preserve homeostatic functions of highly specialized retinal neural cells. If immune privilege is breached, immune stimuli will invade the eye and subsequently trigger acute inflammatory responses. Local resident microglia become active and release numerous immunological factors to protect the integrity of retinal neural cells. Although acute inflammatory responses are necessary to control and eradicate insults to the eye, chronic inflammation can cause retinal tissue damage and cell dysfunction, leading to ocular disease and vision loss. In this review, we summarized features of immune privilege in the retina and the key inflammatory responses, factors, and intracellular pathways activated when retinal immune privilege fails, as well as a highlight of the recent clinical and research advances in ocular immunity and ocular vascular diseases including retinopathy of prematurity, age-related macular degeneration, and diabetic retinopathy.

A novel fasting regimen revealed protein reservation and complement C3 down-regulation after 14-day's continual dietary deprivation

Objectives

The aim is to evaluate the effect of a novel 14-day fasting regimen on the balance between skeletal muscle and adipose tissue composition which might associate with inflammatory factors. Our analysis includes basic physical examinations, clinical laboratory analysis, bioelectrical impedance and biochemical analytic assessments of healthy volunteers.

Methods

Eight healthy subjects were randomly selected from a pool of volunteers to undergo a continual dietary deprivation (CDD) regimen. Individuals were assigned to take Flexible Abrosia (FA, prebiotic combination) plus appropriate mineral supplement of potassium and magnesium at 3 mealtime every day to prevent potential injury from starved intestinal flora and avoid spasms of smooth muscle due to hunger. Physical and medical examinations were conducted and blood samples were collected at following timepoints: before CDD as self-control (0D), day 7 and day 14 during fasting, and 7-21days and/or 2~3mo after refeeding.

Results

The combination of FA and mineral supplements significantly decreased self-reported physical response of starvation, with tolerable hunger-mediated sensations experienced during CDD. Bioelectrical and biochemical results indicated significant reduction in both muscle lean and fat mass on day 7. Meanwhile, markers related to fat composition consistently decreased during and after CDD. In addition, most biochemical marker levels, including serum proteins, reached their inflection points at the 7th day of CDD as compared to the control measurements. Levels of these factors started to show a relative plateau, or reversed direction upon the 14th day of CDD. The exceptions of above factors were myostatin and complement protein C3, which remained at lower concentrations in the blood throughout CDD, and were unable to fully recover toward baseline levels even after 3 months' refeeding.

Conclusion

Our results indicated that human subjects undergoing prolonged dietary restriction were well protected by FA and mineral ions from gut injury or physical discomfort of starvation. Most factors showed a relative plateau response at the end of 14D-CDD. The muscle tissues were well preserved during prolonged fasting, and an improved protein/lipid ratio was observed. Upon refeeding, constant lower levels of myostatin and complement C3 were maintained after CDD implies a long-term beneficial effect in dealing with anti-aging and inflammation.

Complement inhibitors for age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a common eye disease and leading cause of sight loss worldwide. Despite its high prevalence and increasing incidence as populations age, AMD remains incurable and there are no treatments for most patients. Mounting genetic and molecular evidence implicates complement system overactivity as a key driver of AMD development and progression. The last decade has seen the development of several novel therapeutics targeting complement in the eye for the treatment of AMD. This review update encompasses the results of the first randomised controlled trials in this field.

OBJECTIVES

To assess the effects and safety of complement inhibitors in the prevention or treatment of AMD.

SEARCH METHODS

We searched CENTRAL on the Cochrane Library, MEDLINE, Embase, LILACS, Web of Science, ISRCTN registry, ClinicalTrials.gov, and the WHO ICTRP to 29 June 2022 with no language restrictions. We also contacted companies running clinical trials for unpublished data.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with parallel groups and comparator arms that studied complement inhibition for advanced AMD prevention/treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed search results and resolved discrepancies through discussion. Outcome measures evaluated at one year included change in best-corrected visual acuity (BCVA), untransformed and square root-transformed geographic atrophy (GA) lesion size progression, development of macular neovascularisation (MNV) or exudative AMD, development of endophthalmitis, loss of ≥ 15 letters of BCVA, change in low luminance visual acuity, and change in quality of life. We assessed risk of bias and evidence certainty using Cochrane risk of bias and GRADE tools.

MAIN RESULTS

Ten RCTs with 4052 participants and eyes with GA were included. Nine evaluated intravitreal (IVT) administrations against sham, and one investigated an intravenous agent against placebo. Seven studies excluded patients with prior MNV in the non-study eye, whereas the three pegcetacoplan studies did not. The risk of bias in the included studies was low overall. We also synthesised results of two intravitreal agents (lampalizumab, pegcetacoplan) at monthly and every-other-month (EOM) dosing intervals. Efficacy and safety of IVT lampalizumab versus sham for GA For 1932 participants in three studies, lampalizumab did not meaningfully change BCVA given monthly (+1.03 letters, 95% confidence interval (CI) -0.19 to 2.25) or EOM (+0.22 letters, 95% CI -1.00 to 1.44) (high-certainty evidence). For 1920 participants, lampalizumab did not meaningfully change GA lesion growth given monthly (+0.07 mm², 95% CI -0.09 to 0.23; moderate-certainty due to imprecision) or EOM (+0.07 mm², 95% CI -0.05 to 0.19; high-certainty). For 2000 participants, lampalizumab may have also increased MNV risk given monthly (RR 1.77, 95% CI 0.73 to 4.30) and EOM (RR 1.70, 95% CI 0.67 to 4.28), based on low-certainty evidence. The incidence of endophthalmitis in patients treated with monthly and EOM lampalizumab was 4 per 1000 (0 to 87) and 3 per 1000 (0 to 62), respectively, based on moderate-certainty evidence. Efficacy and safety of IVT pegcetacoplan versus sham for GA For 242 participants in one study, pegcetacoplan probably did not meaningfully change BCVA given monthly (+1.05 letters, 95% CI -2.71 to 4.81) or EOM (-1.42 letters, 95% CI -5.25 to 2.41), as supported by moderate-certainty evidence. In contrast, for 1208 participants across three studies, pegcetacoplan meaningfully reduced GA lesion growth when given monthly (-0.38 mm², 95% CI -0.57 to -0.19) and EOM (-0.29 mm², 95% CI -0.44 to -0.13), with high certainty. These reductions correspond to 19.2% and 14.8% versus sham, respectively. A post hoc analysis showed possibly greater benefits in 446 participants with extrafoveal GA given monthly (-0.67 mm², 95% CI -0.98 to -0.36) and EOM (-0.60 mm², 95% CI -0.91 to -0.30), representing 26.1% and 23.3% reductions, respectively. However, we did not have data on subfoveal GA growth to undertake a formal subgroup analysis. In 1502 participants, there is low-certainty evidence that pegcetacoplan may have increased MNV risk when given monthly (RR 4.47, 95% CI 0.41 to 48.98) or EOM (RR 2.29, 95% CI 0.46 to 11.35). The incidence of endophthalmitis in patients treated with monthly and EOM pegcetacoplan was 6 per 1000 (1 to 53) and 8 per 1000 (1 to 70) respectively, based on moderate-certainty evidence. Efficacy and safety of IVT avacincaptad pegol versus sham for GA In a study of 260 participants with extrafoveal or juxtafoveal GA, monthly avacincaptad pegol probably did not result in a clinically meaningful change in BCVA at 2 mg (+1.39 letters, 95% CI -5.89 to 8.67) or 4 mg (-0.28 letters, 95% CI -8.74 to 8.18), based on moderate-certainty evidence. Despite this, the drug was still found to have probably reduced GA lesion growth, with estimates of 30.5% reduction at 2 mg (-0.70 mm², 95% CI -1.99 to 0.59) and 25.6% reduction at 4 mg (-0.71 mm², 95% CI -1.92 to 0.51), based on moderate-certainty evidence. Avacincaptad pegol may have also increased the risk of developing MNV (RR 3.13, 95% CI 0.93 to 10.55), although this evidence is of low certainty. There were no cases of endophthalmitis reported in this study.

AUTHORS' CONCLUSIONS

Despite confirmation of the negative findings of intravitreal lampalizumab across all endpoints, local complement inhibition with intravitreal pegcetacoplan meaningfully reduces GA lesion growth relative to sham at one year. Inhibition of complement C5 with intravitreal avacincaptad pegol is also an emerging therapy with probable benefits on anatomical endpoints in the extrafoveal or juxtafoveal GA population. However, there is currently no evidence that complement inhibition with any agent improves functional endpoints in advanced AMD; further results from the phase 3 studies of pegcetacoplan and avacincaptad pegol are eagerly awaited. Progression to MNV or exudative AMD is a possible emergent adverse event of complement inhibition, requiring careful consideration should these agents be used clinically. Intravitreal administration of complement inhibitors is probably associated with a small risk of endophthalmitis, which may be higher than that of other intravitreal therapies. Further research is likely to have an important impact on our confidence in the estimates of adverse effects and may change these. The optimal dosing regimens, treatment duration, and cost-effectiveness of such therapies are yet to be established.

Geographic atrophy: Mechanism of disease, pathophysiology, and role of the complement system

Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD), characterized by atrophic lesions that first start in the outer retina and progressively expand to cover the macula and the fovea, the center of the macula, leading to irreversible loss of vision over time. GA is distinct from wet or neovascular AMD (nAMD), the other form of advanced AMD. Neovascular AMD is characterized by new invading leaky blood vessels in the macula that can lead to acute vision loss. GA and nAMD may coexist in the same eye. The underlying pathophysiology of GA is complex and thought to involve chronic inflammation due to overactivation of the complement system that leads to the loss of photoreceptors, retinal pigment epithelium (RPE), and the underlying choriocapillaris. The disappearance of these structures appears as sharply demarcated atrophic lesions that are typical of GA. Researchers have reported about 1 million reported cases of GA in the United States, and about 160,000 cases occur per year. The most important risk factors for GA are increasing age and family history. Diagnosis of GA is usually made by using multimodal imaging techniques. Lesions associated with GA are highly heterogeneous, and the growth rate may differ from patient to patient. Despite the progressive nature of GA, the fovea may be spared until much later in the disease, thereby retaining central vision in patients. With time, atrophic lesions may progressively grow to involve the fovea, thereby severely impairing central vision. Vision loss can happen rapidly once the lesions reach the fovea. However, even without the involvement of the fovea, ongoing vision impairment impacting daily life may be present. Median time from GA not involving the center of the fovea (without subfoveal involvement) to GA with lesion boundary affecting the foveal center (subfoveal involvement) ranges from 1.4 to 2.5 years. GA can greatly impact patients' functioning and quality of life and limit their independence by interfering with activities of daily living, including difficulties with reading, driving, watching television, recognizing faces, and being unable to do household chores. No treatments have been available until intravitreal pegcetacoplan was recently approved by the US Food and Drug Administration for GA secondary to AMD. DISCLOSURES: Dr Bakri serves as a consultant to Apellis Pharmaceuticals, as well as AbbVie, Adverum, Eyepoint, iLumen, Iveric Bio, Genentech, Novartis, Outlook Therapeutics, Pixium, Regeneron, Roche, and Regenxbio. Drs Sharp, Luo, and Sarda are employees of Apellis Pharmaceuticals. Dr Bektas and Ms Khan are employees of RTI Health Solutions. Apellis developed and led the concept design of this publication, review and interpretation, approval, and decision to publish. This research was developed under a research contract between RTI Health Solutions and Apellis Pharmaceuticals and was funded by Apellis Pharmaceuticals. This supplement is to describe the disease of geographic atrophy and was funded by Apellis. Apellis Pharmaceuticals has developed Syfovre (pegcetacoplan), the first and only treatment for geographic atrophy.

A Novel Bispecific Fusion Protein Targeting C3b/C4b and VEGF in Patients With nAMD: A Randomized, Open-Label, Phase 1b Study

PURPOSE

To evaluate the safety, tolerability, and efficacy of efdamrofusp alfa in patients with neovascular age-related macular degeneration (nAMD).

DESIGN

Prospective randomized, open-label, multiple ascending-dose, phase 1b study.

METHODS

Patients aged 50 years or older with active choroid neovascularization (CNV) secondary to nAMD were screened from 2 hospitals in 2 provinces in China. The first 9 patients were randomized 2:1 to intravitreally receive efdamrofusp alfa 2 mg at weeks 0, 4, and 8 or aflibercept 2 mg at weeks 0, 4, 8, and 16. After the dose-limiting toxicity assessment, 9 additional patients were randomized 2:1 to intravitreally receive efdamrofusp alfa 4 mg at weeks 0, 4, and 8 or aflibercept 2 mg at weeks 0, 4, 8, and 16. All patients were followed until week 20. Primary outcomes were safety and tolerability of efdamrofusp alfa. Secondary outcomes included changes from baseline in best-corrected visual acuity (BCVA), central subfield thickness (CST) as measured by spectral domain optical coherence tomography (SD-OCT), and CNV area as measured by fluorescein angiography (FA).

RESULTS

A total of 18 patients were enrolled. Six each of them received efdamrofusp alfa 2 mg, efdamrofusp alfa 4 mg, or aflibercept 2 mg, respectively. No dose-limiting toxicity was reported, and all patients completed the study. No ocular serious adverse events were reported. All ocular treatment-emergent adverse events were intravitreal injection related and were mild or moderate in severity. At week 20, mean changes from baseline in BCVA were 5.64 ± 3.56, 8.93 ± 3.59, and 7.92 ± 3.55 letters for patients receiving efdamrofusp alfa 2 mg, efdamrofusp alfa 4 mg and aflibercept 2 mg, respectively. Meanwhile, CST and CNV area reductions indicative of anatomic improvement were observed in the majority of the patients receiving both doses of efdamrofusp alfa and aflibercept.

CONCLUSIONS

Intravitreal efdamrofusp alfa dosed up to 4 mg every 4 weeks was well tolerated in nAMD patients with similar vision acuity and anatomic improvements.

Targeted genotyping of COVID-19 patients reveals a signature of complement C3 and factor B coding SNPs associated with severe infection

We have attempted to explore further the involvement of complement components in the host COVID-19 (Coronavirus disease-19) immune responses by targeted genotyping of COVID-19 adult patients and analysis for missense coding Single Nucleotide Polymorphisms (coding SNPs) of genes encoding Alternative pathway (AP) components. We have identified a small group of common coding SNPs in Survivors and Deceased individuals, present in either relatively similar frequencies (CFH and CFI SNPs) or with stark differences in their relative abundance (C3 and CFB SNPs). In addition, we have identified several sporadic, potentially protective, coding SNPs of C3, CFB, CFD, CFH, CFHR1 and CFI in Survivors. No coding SNPs were detected for CD46 and CD55. Our demographic analysis indicated that the C3 rs1047286 or rs2230199 coding SNPs were present in 60 % of all the Deceased patients (n = 25) (the rs2230199 in 67 % of all Deceased Males) and in 31 % of all the Survivors (n = 105, p = 0.012) (the rs2230199 in 25 % of all Survivor Males). When we analysed these two major study groups using the presence of the C3 rs1047286 or rs2230199 SNPs as potential biomarkers, we noticed the complete absence of the protective CFB rs12614 and rs641153 coding SNPs from Deceased Males compared to Females (p = 0.0023). We propose that in these individuals, C3 carrying the R102G and CFB lacking the R32W or the R32Q amino acid substitutions, may contribute to enhanced association dynamics of the C3bBb AP pre-convertase complex assembly, thus enabling the exploitation of the activation of the Complement Alternative pathway (AP) by SARS-CoV-2.

Latest Development on Genetics of Common Retinal Diseases

Many complex forms of retinal diseases are common and pan-ethnic in occurrence. Among them, neovascular age-related macular degeneration, polypoidal choroidal vasculopathy, and central serous choroid retinopathy involve both choroidopathy and neovascularization with multifactorial etiology. They are sight-threatening and potentially blinding. Early treatment is crucial to prevent disease progression. To understand their genetic basis, candidate gene mutational and association analyses, linkage analysis, genome-wide association studies, transcriptome analysis, next-generation sequencing, which includes targeted deep sequencing, whole-exome sequencing, and whole genome sequencing have been conducted. Advanced genomic technologies have led to the identification of many associated genes. But their etiologies are attributed to complicated interactions of multiple genetic and environmental risk factors. Onset and progression of neovascular age-related macular degeneration and polypoidal choroidal vasculopathy are affected by aging, smoking, lifestyle, and variants in over 30 genes. Although some genetic associations have been confirmed and validated, individual genes or polygenic risk markers of clinical value have not been established. The genetic architectures of all these complex retinal diseases that involve sequence variant quantitative trait loci have not been fully delineated. Recently artificial intelligence is making an impact in the collection and advanced analysis of genetic, investigative, and lifestyle data for the establishment of predictive factors for the risk of disease onset, progression, and prognosis. This will contribute to individualized precision medicine for the management of complex retinal diseases.

Serum 25-Hydroxyvitamin D Is Differentially Associated with Early and Late Age-Related Macular Degeneration in the United States Population

BACKGROUND

Age-related macular degeneration (AMD) has been the leading cause of irreversible blindness in industrialized countries. Emerging data suggest that serum vitamin D levels may be associated with AMD but show mixed results. National-level population data on the relationship between vitamin D and AMD severities are still lacking.

METHODS

We used data from the National Health and Nutrition Examination Survey (NHANES) 2005 to 2008. Retinal photographs were taken and graded for AMD stage. The odds ratio (OR) of AMD and its subtype was calculated after adjusting for confounding factors. Restricted cubic spline (RCS) analyses were used to explore potential non-linear relations.

RESULTS

A total of 5041 participants with a mean age of 59.6 years were included. After adjusting for covariates, participants with higher level of serum 25-hydroxyvitamin D [25(OH)D] had significantly greater odds of early AMD (OR, 1.65; 95% CI, 1.08-2.51) and decreased risk of late AMD (OR, 0.29; 95% CI, 0.09-0.88). When stratified by age, a positive association between the level of serum 25(OH)D and early AMD was present in the <60 years group (OR, 2.79; 95% CI, 1.08-7.29), whereas a negative relation between the level of serum 25(OH)D and late AMD was detected in the ≥60 years group (OR, 0.24; 95% CI, 0.08-0.76).

CONCLUSIONS

A higher level of serum 25(OH)D was related to increased risk of early AMD in those <60 years and decreased risk of late AMD in those ≥60 years.

Knockout of AMD-associated gene POLDIP2 reduces mitochondrial superoxide in human retinal pigment epithelial cells

Genetic and epidemiologic studies have significantly advanced our understanding of the genetic factors contributing to age-related macular degeneration (AMD). In particular, recent expression quantitative trait loci (eQTL) studies have highlighted POLDIP2 as a significant gene that confers risk of developing AMD. However, the role of POLDIP2 in retinal cells such as retinal pigment epithelium (RPE) and how it contributes to AMD pathology are unknown. Here we report the generation of a stable human RPE cell line ARPE-19 with POLDIP2 knockout using CRISPR/Cas, providing an in vitro model to investigate the functions of POLDIP2. We conducted functional studies on the POLDIP2 knockout cell line and showed that it retained normal levels of cell proliferation, cell viability, phagocytosis and autophagy. Also, we performed RNA sequencing to profile the transcriptome of POLDIP2 knockout cells. Our results highlighted significant changes in genes involved in immune response, complement activation, oxidative damage and vascular development. We showed that loss of POLDIP2 caused a reduction in mitochondrial superoxide levels, which is consistent with the upregulation of the mitochondrial superoxide dismutase SOD2. In conclusion, this study demonstrates a novel link between POLDIP2 and SOD2 in ARPE-19, which supports a potential role of POLDIP2 in regulating oxidative stress in AMD pathology.

Contribution of animal models to the mechanistic understanding of Alternative Pathway and Amplification Loop (AP/AL)-driven Complement-mediated Diseases

This review aimed to capture the key findings that animal models have provided around the role of the alternative pathway and amplification loop (AP/AL) in disease. Animal models, particularly mouse models, have been incredibly useful to define the role of complement and the alternative pathway in health and disease; for instance, the use of cobra venom factor and depletion of C3 provided the initial insight that complement was essential to generate an appropriate adaptive immune response. The development of knockout mice have further underlined the importance of the AP/AL in disease, with the FH knockout mouse paving the way for the first anti-complement drugs. The impact from the development of FB, properdin, and C3 knockout mice closely follows this in terms of mechanistic understanding in disease. Indeed, our current understanding that complement plays a role in most conditions at one level or another is rooted in many of these in vivo studies. That C3, in particular, has roles beyond the obvious in innate and adaptive immunity, normal physiology, and cellular functions, with or without other recognized AP components, we would argue, only extends the reach of this arm of the complement system. Humanized mouse models also continue to play their part. Here, we argue that the animal models developed over the last few decades have truly helped define the role of the AP/AL in disease.

Polygenic Risk Score Impact on Susceptibility to Age-Related Macular Degeneration in Polish Patients

Age-related macular degeneration (AMD) is a common retina degenerative disease with a complex genetic and environmental background. This study aimed to determine the polygenic risk score (PRS) stratification between the AMD case and control patients. The PRS model was established on the targeted sequencing data of a cohort of 471 patients diagnosed with AMD and 167 healthy controls without symptoms of retinal degeneration. The highest predictive value to the target dataset was achieved for a 22-variant model with a p-value lower than threshold PT = 0.0123. The median PRS for cases was higher by 1.1 than for control samples (95% CI: (−1.19; −0.85)). The patients in the highest quantile had a significantly higher relative risk of developing AMD than those in the lowest reference quantile (OR = 35.13, 95% CI: (7.9; 156.1), p < 0.001). The diagnostic ability was investigated using ROC analysis with AUC = 0.76 (95% CI: (0.72; 0.80)). The polygenic susceptibility to AMD may be the starting point to expand AMD diagnostics based on rare highly penetrant variants and investigate associations with disease progression and treatment response in Polish patients in future studies.

A novel method for real-time analysis of the complement C3b:FH:FI complex reveals dominant negative CFI variants in age-related macular degeneration

Age-related macular degeneration (AMD) is linked to 2 main disparate genetic pathways: a chromosome 10 risk locus and the alternative pathway (AP) of complement. Rare genetic variants in complement factor H (CFH; FH) and factor I (CFI; FI) are associated with AMD. FH acts as a soluble cofactor to facilitate FI's cleavage and inactivation of the central molecule of the AP, C3b. For personalised treatment, sensitive assays are required to define the functional significance of individual AP genetic variants. Generation of recombinant FI for functional analysis has thus far been constrained by incomplete processing resulting in a preparation of active and inactive protein. Using an internal ribosomal entry site (IRES)-Furin-CFI expression vector, fully processed FI was generated with activity equivalent to serum purified FI. By generating FI with an inactivated serine protease domain (S525A FI), a real-time surface plasmon resonance assay of C3b:FH:FI complex formation for characterising variants in CFH and CFI was developed and correlated well with standard assays. Using these methods, we further demonstrate that patient-associated rare genetic variants lacking enzymatic activity (e.g. CFI I340T) may competitively inhibit the wild-type FI protein. The dominant negative effect identified in inactive factor I variants could impact on the pharmacological replacement of FI currently being investigated for the treatment of dry AMD.

Systems genomics in age-related macular degeneration

Genomic studies in age-related macular degeneration (AMD) have identified genetic variants that account for the majority of AMD risk. An important next step is to understand the functional consequences and downstream effects of the identified AMD-associated genetic variants. Instrumental for this next step are 'omics' technologies, which enable high-throughput characterization and quantification of biological molecules, and subsequent integration of genomics with these omics datasets, a field referred to as systems genomics. Single cell sequencing studies of the retina and choroid demonstrated that the majority of candidate AMD genes identified through genomic studies are expressed in non-neuronal cells, such as the retinal pigment epithelium (RPE), glia, myeloid and choroidal cells, highlighting that many different retinal and choroidal cell types contribute to the pathogenesis of AMD. Expression quantitative trait locus (eQTL) studies in retinal tissue have identified putative causal genes by demonstrating a genetic overlap between gene regulation and AMD risk. Linking genetic data to complement measurements in the systemic circulation has aided in understanding the effect of AMD-associated genetic variants in the complement system, and supports that protein QTL (pQTL) studies in plasma or serum samples may aid in understanding the effect of genetic variants and pinpointing causal genes in AMD. A recent epigenomic study fine-mapped AMD causal variants by determing regulatory regions in RPE cells differentiated from induced pluripotent stem cells (iPSC-RPE). Another approach that is being employed to pinpoint causal AMD genes is to produce synthetic DNA assemblons representing risk and protective haplotypes, which are then delivered to cellular or animal model systems. Pinpointing causal genes and understanding disease mechanisms is crucial for the next step towards clinical translation. Clinical trials targeting proteins encoded by the AMD-associated genomic loci C3, CFB, CFI, CFH, and ARMS2/HTRA1 are currently ongoing, and a phase III clinical trial for C3 inhibition recently showed a modest reduction of lesion growth in geographic atrophy. The EYERISK consortium recently developed a genetic test for AMD that allows genotyping of common and rare variants in AMD-associated genes. Polygenic risk scores (PRS) were applied to quantify AMD genetic risk, and may aid in predicting AMD progression. In conclusion, genomic studies represent a turning point in our exploration of AMD. The results of those studies now serve as a driving force for several clinical trials. Expanding to omics and systems genomics will further decipher function and causality from the associations that have been reported, and will enable the development of therapies that will lessen the burden of AMD.

Genome-Wide DNA Methylation Profile Indicates Potential Epigenetic Regulation of Aging in the Rhesus Macaque Thymus

We analyzed whole-genome bisulfite sequencing (WGBS) and RNA sequencing data of two young (1 year old) and two adult (9 years old) rhesus macaques (Macaca mulatta) to characterize the genomic DNA methylation profile of the thymus and explore the molecular mechanism of age-related changes in the thymus. Combining the two-omics data, we identified correlations between DNA methylation and gene expression and found that DNA methylation played an essential role in the functional changes of the aging thymus, especially in immunity and coagulation. The hypomethylation levels of C3 and C5AR2 and the hypermethylation level of C7 may lead to the high expressions of these genes in adult rhesus macaque thymuses, thus activating the classical complement pathway and the alternative pathway and enhancing their innate immune function. Adult thymuses had an enhanced coagulation pathway, which may have resulted from the hypomethylation and upregulated expressions of seven coagulation-promoting factor genes (F13A1, CLEC4D, CLEC4E, FCN3, PDGFRA, FGF2 and FGF7) and the hypomethylation and low expression of CPB2 to inhibit the degradation of blood clots. Furthermore, the functional decline in differentiation, activation and maturation of T cells in adult thymuses was also closely related to the changes in methylation levels and gene expression levels of T cell development genes (CD3G, GAD2, ADAMDEC1 and LCK) and the thymogenic hormone gene TMPO. A comparison of the age-related methylated genes among four mammal species revealed that most of the epigenetic clocks were species-specific. Furthermore, based on the genomic landscape of allele-specific DNA methylation, we identified several age-related clustered sequence-dependent allele-specific DNA methylated (cS-ASM) genes. Overall, these DNA methylation patterns may also help to assist with understanding the mechanisms of the aging thymus with the epigenome.

Transcriptome analysis of AAV-induced retinopathy models expressing human VEGF, TNF-α, and IL-6 in murine eyes

Retinopathies are multifactorial diseases with complex pathologies that eventually lead to vision loss. Animal models facilitate the understanding of the pathophysiology and identification of novel treatment options. However, each animal model reflects only specific disease aspects and understanding of the specific molecular changes in most disease models is limited. Here, we conducted transcriptome analysis of murine ocular tissue transduced with recombinant Adeno-associated viruses (AAVs) expressing either human VEGF-A, TNF-α, or IL-6. VEGF expression led to a distinct regulation of extracellular matrix (ECM)-associated genes. In contrast, both TNF-α and IL-6 led to more comparable gene expression changes in interleukin signaling, and the complement cascade, with TNF-α-induced changes being more pronounced. Furthermore, integration of single cell RNA-Sequencing data suggested an increase of endothelial cell-specific marker genes by VEGF, while TNF-α expression increased the expression T-cell markers. Both TNF-α and IL-6 expression led to an increase in macrophage markers. Finally, transcriptomic changes in AAV-VEGF treated mice largely overlapped with gene expression changes observed in the oxygen-induced retinopathy model, especially regarding ECM components and endothelial cell-specific gene expression. Altogether, our study represents a valuable investigation of gene expression changes induced by VEGF, TNF-α, and IL-6 and will aid researchers in selecting appropriate animal models for retinopathies based on their agreement with the human pathophysiology.

Differential expression of plasma exosomal microRNA in severe acute pancreatitis

The incidence rate of acute pancreatitis is increasing, and severe acute pancreatitis (SAP) is associated with a high mortality rate, which may be reduced by a deeper understanding of its pathogenesis. In addition, an early determination of the severity of acute pancreatitis remains challenging. The aim of this study was to match potential biomarkers for early identification and monitoring of acute pancreatitis and to shed light on the underlying pathogenic mechanisms of SAP. The expression levels of plasma exosomal microRNA (miRNA) in patients with pancreatitis have been associated with the disease. Thus, this study compared the expression levels of exosomal miRNA in plasma collected from four patients with SAP and from four healthy participants. Analyses of the miRNA expression profiles indicated that three previously unreported miRNAs were differentially expressed in the patient group: Novel1, which was downregulated, and Novel2 and Novel3, which were upregulated. The miRNA target genes for those novel miRNAs were predicted using Metascape. Of these miRNA target genes, those that were also differentially expressed at different time points after disease induction in a mouse model of acute pancreatitis were determined. The gene for complement component 3 (C3), a target gene of Novel3, was the only gene matched in both the patient group and the mouse model. C3 appeared at most of the time points assessed after induction of acute pancreatitis in mice. These findings are foundational evidence that C3 warrants further study as an early biomarker of SAP, for investigating underlying pathogenic mechanisms of SAP, and as a therapeutic target for ameliorating the occurrence or development of SAP.

Targeting the Complement Cascade for Treatment of Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in the elderly population. AMD is characterized in its late form by neovascularization (wet type) or geographic atrophy of the retinal pigment epithelium cell layer (dry type). Regarding the latter type, there is growing evidence supporting an association between the pathophysiology of dry AMD and key proteins in the complement cascade. The complement cascade works as a central part of the innate immune system by defending against foreign pathogens and modified self-tissues. Through three distinct pathways, a series of plasma and membrane-associated serum proteins are activated upon identification of a foreign entity. Several of these proteins have been implicated in the development and progression of dry AMD. Potential therapeutic targets include C1q, C3, C5, complement factors (B, D, H, I), membrane attack complex, and properdin. In this review, we provide an understanding of the role of the complement system in dry AMD and discuss the emerging therapies in early phase clinical trials. The tentative hope is that these drugs may offer the potential to intervene at earlier stages in dry AMD pathogenesis, thereby preventing progression to late disease.

Transcriptomic and proteomic retinal pigment epithelium signatures of age-related macular degeneration

There are currently no treatments for geographic atrophy, the advanced form of age-related macular degeneration. Hence, innovative studies are needed to model this condition and prevent or delay its progression. Induced pluripotent stem cells generated from patients with geographic atrophy and healthy individuals were differentiated to retinal pigment epithelium. Integrating transcriptional profiles of 127,659 retinal pigment epithelium cells generated from 43 individuals with geographic atrophy and 36 controls with genotype data, we identify 445 expression quantitative trait loci in cis that are asssociated with disease status and specific to retinal pigment epithelium subpopulations. Transcriptomics and proteomics approaches identify molecular pathways significantly upregulated in geographic atrophy, including in mitochondrial functions, metabolic pathways and extracellular cellular matrix reorganization. Five significant protein quantitative trait loci that regulate protein expression in the retinal pigment epithelium and in geographic atrophy are identified - two of which share variants with cis- expression quantitative trait loci, including proteins involved in mitochondrial biology and neurodegeneration. Investigation of mitochondrial metabolism confirms mitochondrial dysfunction as a core constitutive difference of the retinal pigment epithelium from patients with geographic atrophy. This study uncovers important differences in retinal pigment epithelium homeostasis associated with geographic atrophy.

Molecular Genetic Mechanisms in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is among the leading causes of irreversible blindness worldwide. In addition to environmental risk factors, such as tobacco use and diet, genetic background has long been established as a major risk factor for the development of AMD. However, our ability to predict disease risk and personalize treatment remains limited by our nascent understanding of the molecular mechanisms underlying AMD pathogenesis. Research into the molecular genetics of AMD over the past two decades has uncovered 52 independent gene variants and 34 independent loci that are implicated in the development of AMD, accounting for over half of the genetic risk. This research has helped delineate at least five major pathways that may be disrupted in the pathogenesis of AMD: the complement system, extracellular matrix remodeling, lipid metabolism, angiogenesis, and oxidative stress response. This review surveys our current understanding of each of these disease mechanisms, in turn, along with their associated pathogenic gene variants. Continued research into the molecular genetics of AMD holds great promise for the development of precision-targeted, personalized therapies that bring us closer to a cure for this debilitating disease.

Bioengineering approaches for modelling retinal pathologies of the outer blood-retinal barrier

Alterations of the junctional complex of the outer blood-retinal barrier (oBRB), which is integrated by the close interaction of the retinal pigment epithelium, the Bruch's membrane, and the choriocapillaris, contribute to the loss of neuronal signalling and subsequent vision impairment in several retinal inflammatory disorders such as age-related macular degeneration and diabetic retinopathy. Reductionist approaches into the mechanisms that underlie such diseases have been hindered by the absence of adequate in vitro models using human cells to provide the 3D dynamic architecture that enables expression of the in vivo phenotype of the oBRB. Conventional in vitro cell models are based on 2D monolayer cellular cultures, unable to properly recapitulate the complexity of living systems. The main drawbacks of conventional oBRB models also emerge from the cell sourcing, the lack of an appropriate Bruch's membrane analogue, and the lack of choroidal microvasculature with flow. In the last years, the advent of organ-on-a-chip, bioengineering, and stem cell technologies is providing more advanced 3D models with flow, multicellularity, and external control over microenvironmental properties. By incorporating additional biological complexity, organ-on-a-chip devices can mirror physiologically relevant properties of the native tissue while offering additional set ups to model and study disease. In this review we first examine the current understanding of oBRB biology as a functional unit, highlighting the coordinated contribution of the different components to barrier function in health and disease. Then we describe recent advances in the use of pluripotent stem cells-derived retinal cells, Bruch's membrane analogues, and co-culture techniques to recapitulate the oBRB. We finally discuss current advances and challenges of oBRB-on-a-chip technologies for disease modelling.

Targeting C3b/C4b and VEGF with a bispecific fusion protein optimized for neovascular age-related macular degeneration therapy

Antiangiogenesis therapies targeting vascular endothelial growth factor (VEGF) have revolutionized the treatment of neovascular ocular diseases, including neovascular age-related macular degeneration (nAMD). Compelling evidence has implicated the vital role of complement system dysregulation in AMD pathogenesis, implying it as a potential therapeutic strategy for geographic atrophy in dry AMD and to enhance the efficacy of anti-VEGF monotherapies in nAMD. This study reports the preclinical assessment and phase 1 clinical outcomes of a bispecific fusion protein, efdamrofusp alfa (code: IBI302), which is capable of neutralizing both VEGF isoforms and C3b/C4b. Efdamrofusp alfa showed superior efficacy over anti-VEGF monotherapy in a mouse laser-induced choroidal neovascularization (CNV) model after intravitreal delivery. Dual inhibition of VEGF and the complement activation was found to further inhibit macrophage infiltration and M2 macrophage polarization. Intravitreal efdamrofusp alfa demonstrated favorable safety profiles and exhibited antiangiogenetic efficacy in a nonhuman primate laser-induced CNV model. A phase 1 dose-escalating clinical trial (NCT03814291) was thus conducted on the basis of the preclinical data. Preliminary results showed that efdamrofusp alfa was well tolerated in patients with nAMD. These data suggest that efdamrofusp alfa might be effective for treating nAMD and possibly other complement-related ocular conditions.

Age-Related Maculopathy Susceptibility 2 and Complement Factor H Polymorphism and Intraocular Complement Activation in Neovascular Age-Related Macular Degeneration

Purpose

To investigate the association of risk alleles in complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) with complement activation products in the aqueous humor in eyes with neovascular age-related macular degeneration (nAMD) including polypoidal choroidal vasculopathy (PCV), retinal angiomatous proliferation (RAP), and pachychoroid neovasculopathy (PNV).

Design

Prospective, comparative, observational study.

Participants

Treatment-naïve patients with nAMD and cataract patients as controls.

Methods

The study included 236 eyes of 236 patients with nAMD and 49 control eyes of 49 patients. Aqueous humor samples were collected from 67 eyes with drusen-associated nAMD, 72 eyes with PCV, 26 eyes with RAP, and 71 eyes with PNV before intravitreal anti-VEGF injection and cataract surgery in the 49 control eyes. Clinical samples were measured for complement component 3a (C3a), C4a, and C5a using a bead-based immunoassay. Genotyping of the ARMS2 A69S (rs10490924), CFH I62V (rs800292), and CFH Y402H (rs1061170) was performed using TaqMan genotyping.

Main Outcome Measures

The levels of complement activation products (C3a, C4a, and C5a) in the aqueous humor in each genotype of ARMS2 and CFH.

Results

The C3a level in the aqueous humor was significantly elevated (P = 0.006) in patients with nAMD and the ARMS2 A69S risk allele, whereas the levels of the complement activation products were not associated with CFH I62V and Y402H genotypes. Among the control eyes, no significant differences were seen in any complement activation products for all genetic polymorphisms. The levels of the complement activation products in the aqueous humor of eyes with the nAMD subtypes for each genetic polymorphism did not show significant differences.

Conclusions

The C3a concentration in the aqueous humor was significantly higher in Japanese nAMD patients with the ARMS2 A69S risk allele, whereas it was not elevated in the patients with CFH I62V. Age-related maculopathy susceptibility 2 A69S polymorphism is strongly associated with local complement activation in nAMD patients.

The yin and the yang of early classical pathway complement disorders

The classical pathway of the complement cascade has been recognized as a key activation arm, partnering with the lectin activation arm and the alternative pathway to cleave C3 and initiate the assembly of the terminal components. While deficiencies of classical pathway components have been recognized since 1966, only recently have gain-of-function variants been described for some of these proteins. Loss-of-function variants in C1, C4, and C2 are most often associated with lupus and systemic infections with encapsulated bacteria. C3 deficiency varies slightly from this phenotypic class with membranoproliferative glomerulonephritis and infection as the dominant phenotypes. The gain-of- function variants recently described for C1r and C1s lead to periodontal Ehlers Danlos syndrome, a surprisingly structural phenotype. Gain-of-function in C3 and C2 are associated with endothelial manifestations including hemolytic uremic syndrome and vasculitis with C2 gain-of-function variants thus far having been reported in patients with a C3 glomerulopathy. This review will discuss the loss-of-function and gain-of-function phenotypes and place them within the larger context of complement deficiencies.

Biomarkers as Predictive Factors of Anti-VEGF Response

Age-related macular degeneration is the main cause of irreversible vision in developed countries, and intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections are the current gold standard treatment today. Although anti-VEGF treatment results in important improvements in the course of this disease, there is a considerable number of patients not responding to the standardized protocols. The knowledge of how a patient will respond or how frequently retreatment might be required would be vital in planning treatment schedules, saving both resource utilization and financial costs, but today, there is not an ideal biomarker to use as a predictive response to ranibizumab therapy. Whole blood and blood mononuclear cells are the samples most studied; however, few reports are available on other important biofluid samples for studying this disease, such as aqueous humor. Moreover, the great majority of studies carried out to date were focused on the search for SNPs in genes related to AMD risk factors, but miRNAs, proteomic and metabolomics studies have rarely been conducted in anti-VEGF-treated samples. Here, we propose that genomic, proteomic and/or metabolomic markers could be used not alone but in combination with other methods, such as specific clinic characteristics, to identify patients with a poor response to anti-VEGF treatment to establish patient-specific treatment plans.

Salivary Proteome, Inflammatory, and NETosis Biomarkers in Older Adult Practitioners and Nonpractitioners of Physical Exercise

Since aging has been associated with increased production of inflammatory biomarkers, the ability to monitor older adults repeatedly is highly desirable, and saliva is an interesting biofluid for the search of biomarkers, as it is easily accessible in a noninvasive manner. However, given the incipient knowledge of salivary biomarkers in aging and its relationship to physical exercise, the present study is aimed at evaluating the protein expression and the levels of inflammatory and NETosis biomarkers in the saliva of practitioners (PE) and nonpractitioners (NPE) of physical exercise older adults. Six (6) practitioner and 4 nonpractitioner older adults were enrolled in this study. Unstimulated whole saliva was collected for analysis of the proteome by label-free mass spectrometry, as well as of the inflammatory status by evaluation of C-reactive protein (CRP), vascular endothelial growth factor (VEGF), and cytokines (TNF-α, interleukin- (IL-) 1β, and IL-8), while NETosis was assessed by myeloperoxidase (MPO) and neutrophil elastase. Regarding oral health, the decayed, missing, and filled teeth (DMF-T) index, bleeding on probing, suppuration, and probing depth measurement (mm) were evaluated. In addition, functional capacity was investigated using the General Physical Fitness Index (GPFI). In relation to the proteome analysis, 93 and 143 proteins were found exclusively in the PE and NPE groups, respectively; 224 proteins were common to both groups. Among these proteins, 10 proteins showed statistical difference ( $p<0.05$ ) between the groups: alpha-2-macroglobulin, component 3 of the complement, serotransferrin, and protein soluble in brain acid 1 were less expressed, while lactotransferrin, alpha-amylase 1, S100-A8, S100-A9, lactoperoxidase, and galectin-3 binding protein were more expressed in the PE group. No differences between groups were observed in the analysis of inflammatory and NETosis biomarkers. This study shows the potential utility of saliva for detecting protein biomarkers in a noninvasive biological sample of the elderly population.

Association of Age-Related Macular Degeneration with Prior Hyperthyroidism and Hypothyroidism: A Case-Control Study

Prior studies suggest a possible association between thyroid disease and the subsequent development of age-related macular degeneration (AMD), although it remains inconclusive. This study aimed to evaluate the association of AMD with prior hyper-/hypothyroidism based on nationwide population-based data. We retrieved records of the study patients from the National Health Insurance Research Database, 7522 patients with a first-time diagnosis of AMD and 7522 propensity score-matched controls. Multiple logistic regression analyses were performed to explore the association of neovascular AMD with previously diagnosed hyperthyroidism or hypothyroidism. The Chi-square test shows that there was a statistically significant difference in the prevalence of prior hyperthyroidism between cases and controls (1.18 vs. 0.13%, p < 0.001). Furthermore, there was a statistically significant difference the prevalence of prior hypothyroidism between cases and controls (0.44 vs. 0.69%, p < 0.001). Multiple logistic regression analysis reveals that AMD was statistically and significantly associated with prior hyperthyroidism after adjusting for age, sex, monthly income, geographical location, urbanization level, hypertension, hyperlipidemia, diabetes, and coronary heart disease (odds ratio (OR) = 9.074, 95% CI = 4.713−17.471). The adjusted OR of prior hypothyroidism in patients with AMD was 3.794 (95% CI: 2.099~6.858) when compared to the controls. We conclude that patients with thyroid dysfunction are at higher risk of developing AMD Results suggest that these patients could benefit from proactive regular eye checkups to detect evolving eye pathology, even while vision remains normal during the initial phases.

Integrating external controls in case–control studies improves power for rare‐variant tests

Large-scale sequencing and genotyping data provide an opportunity to integrate external samples as controls to improve power of association tests. However, due to the systematic differences between genotyped samples from different studies, naively aggregating the controls could lead to inflation in Type I error rates. There has been recent effort to integrate external controls while adjusting for batch effect, such as the integrating External Controls into Association Test (iECAT) and its score-based single variant tests. Building on the original iECAT framework, we propose an iECAT-Score region-based test that increases power for rare-variant tests when integrating external controls. This method assesses the systematic batch effect between internal and external samples at each variant and constructs compound shrinkage score statistics to test for the joint genetic effect within a gene or a region, while adjusting for covariates and population stratification. Through simulation studies, we demonstrate that the proposed method controls for Type I error rates and improves power in rare-variant tests. The application of the proposed method to the association studies of age-related macular degeneration (AMD) from the International AMD Genomics Consortium and UK Biobank revealed novel rare-variant associations in gene DXO. Through the incorporation of external controls, the iECAT methods offer a powerful suite to identify disease-associated genetic variants, further shedding light on future directions to investigate roles of rare variants in human diseases.