Association of CRP levels with ARMS2 and CFH variants in age-related macular degeneration

The Impact of Blood and Urine Biomarkers on Age-Related Macular Degeneration: Insights from Mendelian Randomization and Cross-sectional Study from NHANES

INTRODUCTION

Age-related macular degeneration (AMD) is a leading cause of blindness, affecting millions worldwide. Its complex pathogenesis involves a variety of risk factors, including lipid metabolism and inflammation. This study aims to elucidate the causal relationships between biomarkers related to these processes and AMD, leveraging Mendelian randomization (MR) and cross-sectional analysis from the National Health and Nutrition Examination Survey (NHANES).

METHOD

We conducted a two-phase study, initially using MR to explore the causality between 35 biomarkers and various AMD subtypes, followed by observational analysis with NHANES data to validate these findings.

RESULTS

MR analysis identified a protective role of TG and a risk factor role of HDL-C and CRP in AMD development. NHANES data corroborated these findings, highlighting a nuanced relationship between these biomarkers and AMD. Notably, lipid metabolism-related biomarkers showed stronger associations with early AMD, whereas CRP's significance was pronounced in late AMD.

CONCLUSION

This comprehensive analysis, combining MR with NHANES data, reinforces the importance of lipid metabolism and inflammation in AMD's etiology. Future research should further investigate these biomarkers' mechanisms and their potential as therapeutic targets for AMD prevention and treatment.

C-reactive protein-complement factor H axis as a biomarker of activity in early and intermediate age-related macular degeneration

Purpose

To determine and compare the serum levels of complement Factor H (FH), monomeric C-Reactive Protein (mCRP) and pentameric C-Reactive protein (pCRP) in patients with age-related macular degeneration (AMD) and to correlate them with clinical, structural and functional parameters.

Methods

Cross-sectional observational study. One hundred thirty-nine individuals (88 patients and 51 healthy controls) from two referral centers were included and classified into three groups: early or intermediate AMD (n=33), advanced AMD (n=55), and age and sex matched healthy controls (n=51). Serum levels of FH, mCRP, and pCRP were determined and correlated with clinical and imaging parameters.

Results

Patients with intermediate AMD presented FH levels significantly lower than controls [186.5 (72.1-931.8) µg/mL vs 415.2 (106.1-1962.2) µg/mL; p=0.039] and FH levels <200 µg/mL were associated with the presence of drusen and pigmentary changes in the fundoscopy (p=0.002). While no differences were observed in pCRP and mCRP levels, and mCRP was only detected in less than 15% of the included participants, women had a significantly higher detection rate of mCRP than men (21.0% vs. 3.8%, p=0.045). In addition, the ratio mCRP/FH (log) was significantly lower in the control group compared to intermediate AMD (p=0.031). Visual acuity (p<0.001), macular volume (p<0.001), and foveal thickness (p=0.034) were significantly lower in the advanced AMD group, and choroidal thickness was significantly lower in advanced AMD compared to early/intermediate AMD (p=0.023).

Conclusion

Intermediate AMD was associated in our cohort with decreased serum FH levels together with increased serum mCRP/FH ratio. All these objective serum biomarkers may suggest an underlying systemic inflammatory process in early/intermediate AMD patients.

A Treat-and-Extend Regimen of Intravitreal Brolucizumab for Exudative Age-Related Macular Degeneration Refractory to Aflibercept: A 12-Month Result

We aimed to investigate whether a treat-and-extend regimen of intravitreal brolucizumab (6.0 mg/0.05 mL) is effective for eyes with exudative age-related macular degeneration (AMD) refractory to aflibercept for 12 months. Sixty eyes from 56 patients receiving brolucizumab for exudative AMD refractory to aflibercept were included. Patients received a mean of 30.1 aflibercept administrations for a mean 67.9-month follow-up. All patients exhibited exudation on optical coherence tomography (OCT) despite regular 4-8 weeks of aflibercept administration. Visit 1 was scheduled at the same interval from the last aflibercept injection to the baseline. The treatment interval was extended or shortened by 1-2 weeks depending on the presence or absence of exudation on OCT. After switching to brolucizumab, the follow-up interval significantly extended at 12 months (before switching: 7.6 ± 3.8 weeks vs. at 12 months: 12.1 ± 6.2 weeks, p = 1.3 × 10^-7). Forty-three percent of the eyes achieved a dry macula at 12 months after switching. However, the best-corrected visual acuity did not improve at any visit. Morphologically, the central retinal thickness and subfoveal choroidal thickness significantly decreased from baseline at 12 months (p = 3.6 × 10^-3 and 1.0 × 10^-3, respectively). Switching to brolucizumab can be considered to extend the treatment interval in eyes with exudative AMD refractory to aflibercept.

Consequences of a Rare Complement Factor H Variant for Age-Related Macular Degeneration in the Amish

Purpose

Genetic variants in the complement factor H gene (CFH) have been consistently implicated in age-related macular degeneration (AMD) risk. However, their functional effects are not fully characterized. We previously identified a rare, AMD-associated variant in CFH (P503A, rs570523689) in 19 Amish individuals, but its functional consequences were not investigated.

Methods

We performed genotyping for CFH P503A in 1326 Amish individuals to identify additional risk allele carriers. We examined differences for age at AMD diagnosis between carriers and noncarriers. In blood samples from risk allele carriers and noncarriers, we quantified (i) CFH RNA expression, (ii) CFH protein expression, and (iii) C-reactive protein (CRP) expression. Potential changes to the CFH protein structure were interrogated computationally with Phyre² and Chimera software programs.

Results

We identified 39 additional carriers from Amish communities in Ohio and Indiana. On average, carriers were younger than noncarriers at AMD diagnosis, but this difference was not significant. CFH transcript and protein levels in blood samples from Amish carriers and noncarriers were also not significantly different. CRP levels were also comparable in plasma samples from carriers and noncarriers. Computational protein modeling showed slight changes in the CFH protein conformation that were predicted to alter interactions between the CFH 503 residue and other neighboring residues.

Conclusions

In total, we have identified 58 risk allele carriers for CFH P503A in the Ohio and Indiana Amish. Although we did not detect significant differences in age at AMD diagnosis or expression levels of CFH in blood samples from carriers and noncarriers, we observed modest structural changes to the CFH protein through in silico modeling. Based on our functional and computational observations, we hypothesize that CFH P503A may affect CFH binding or function rather than expression, which would require additional research to confirm.

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.

Do Oral Pathogens Inhabit the Eye and Play a Role in Ocular Diseases?

Fascinatingly, the immune-privileged healthy eye has a small unique population of microbiota. The human microbiome project led to continuing interest in the ocular microbiome. Typically, ocular microflorae are commensals of low diversity that colonize the external and internal sites of the eye, without instigating any disorders. Ocular commensals modulate immunity and optimally regulate host defense against pathogenic invasion, both on the ocular surface and neuroretina. Yet, any alteration in this symbiotic relationship culminates in the perturbation of ocular homeostasis and shifts the equilibrium toward local or systemic inflammation and, in turn, impaired visual function. A compositional variation in the ocular microbiota is associated with surface disorders such as keratitis, blepharitis, and conjunctivitis. Nevertheless, innovative studies now implicate non-ocular microbial dysbiosis in glaucoma, age-related macular degeneration (AMD), uveitis, and diabetic retinopathy. Accordingly, prompt identification of the extra-ocular etiology and a methodical understanding of the mechanisms of invasion and host-microbial interaction is of paramount importance for preventative and therapeutic interventions for vision-threatening conditions. This review article aims to explore the current literature evidence to better comprehend the role of oral pathogens in the etiopathogenesis of ocular diseases, specifically AMD.

The combination therapy of subtenon triamcinolone acetonide injection and intravitreal brolucizumab for brolucizumab-related intraocular inflammation

RATIONALE

Brolucizumab is a novel anti-vascular endothelial growth factor agent with clinical trials demonstrating excellent efficacy for neovascular age-related macular degeneration (AMD) in both visual and anatomic outcomes. However, there is concern of intraocular inflammation (IOI), and we propose concurrent subtenon triamcinolone acetonide (STTA) to prevent IOI.

PATIENT CONCERN

A 73-year-old man was treated with aflibercept for neovascular AMD in his right eye. Despite 11 months of monthly intravitreal aflibercept injections, optical coherence tomography demonstrated persistent exudation. Ten days following his second brolucizumab injection, the patient presented with decreased vision due to vitritis in his right eye.

DIAGNOSIS

Brolucizumab-related IOI in neovascular AMD refractory to aflibercept.

INTERVENTIONS

A combination therapy involving of intravitreal brolucizumab and STTA.

OUTCOMES

The anti-vascular endothelial growth factor inhibitor was changed back to aflibercept; however, exudation persisted. Therefore, a combination therapy involving STTA (5 mg/0.5 mL) and intravitreal injection of brolucizumab (6.0 mg/0.05 mL) was performed to treat the exudation and as prophylaxis to recurrent IOI. Combination therapy achieved no recurrent IOI and resolution of exudation with 8-week treatment intervals.

LESSONS

This case might indicate that STTA is not only an optimal treatment option for brolucizumab-related IOI but also a preventive agent for this condition.

Five-Year Outcome of Aflibercept Monotherapy for Exudative Age-Related Macular Degeneration with Good Baseline Visual Acuity

We investigated the long-term visual and anatomical outcomes of aflibercept monotherapy for exudative age-related macular degeneration (AMD) with good baseline best-corrected visual acuity (BCVA). A medical chart review was performed for 40 consecutive patients with baseline decimal BCVA ≥ 0.6 secondary to exudative AMD. Three monthly injections were administrated, and thereafter additional injection was performed if needed over 5 years. In total, 13 eyes with neovascular AMD (nAMD) and 27 eyes with polypoidal choroidal vasculopathy (PCV) were enrolled. In both groups, the mean BCVA significantly improved at the 12-month visit (p < 0.05). However, the significant improvement in BCVA disappeared at the 24-month visit, and the final mean BCVA was equivalent to that at baseline (p = 0.17 in the nAMD group and p = 0.15 in the PCV group). The median number of injections required after the loading dose was 15.0 during the 5-year follow-up (nAMD:15.0 vs. PCV:15). During the study period, 37 (92.5%) eyes required retreatment(s). Cox regression analysis demonstrated that the protective allele of ARMS2 A69S was associated with a retreatment-free period from the initial injection (p = 0.041, repeated forward selection method). As-needed aflibercept monotherapy is a preferable treatment option for exudative AMD with good initial visual acuity regardless of nAMD or PCV during the 5-year study period.

Association of HTRA1 and CFH gene polymorphisms with age-related macular degeneration in Ningbo, China

BACKGROUND

Age-related macular degeneration (AMD) is one of the major causes of blindness, and the incidence of this disease has been increasing in recent years.

OBJECTIVE

To investigate the association between the single nucleotide polymorphisms (SNPs) of the high temperature requirement factor A-1 (HTRA1) and complement factor H (CFH) genes and susceptibility to AMD in Ningbo, China.

METHODS

Ninety-eight patients with AMD and seventy-three controls were recruited at the Sixth Hospital of Ningbo from August 2017 to April 2019 in China. Genomic DNA was extracted from the venous blood provided by the hospital, and the genotypes of the AMD susceptibility genes CFH and HTAR1 were detected by polymerase chain reaction and sequenced directly. The SNPs rs11200638 on the HTRA1 gene and rs3753394 on the CFH gene were selected for genotype and association analysis. The correlations between the different genotypes of HTRA1 and CFH and AMD were analysed by the Chi-squared test.

RESULTS

All the genotypes adhered to the Hardy-Weinberg equilibrium. There were three genotypes (AA, AG and GG) in HTRA1 (rs11200638). The differences in genotypes and allele frequency between the AMD group and the control group were statistically significant (P < 0.05). The A allele was a risk allele (OR: 4.19, 95% Cl: 2.28 ~ 7.70, P < 0.05), with a frequency of 61.7% in patients versus 43.8% in controls. However, the rs3753394 SNP in CFH was not associated with AMD in our study (P > 0.05).

CONCLUSIONS

The rs11200638 SNP of the HTRA1 gene is associated with AMD, and the AA genotype is a risk factor for AMD in the Ningbo population. There is no significant correlation between the rs3753394 SNP of the CFH gene and AMD.

Eye on the Enigmatic Link: Dysbiotic Oral Pathogens in Ocular Diseases; The Flip Side

Mouth and associated structures were regarded as separate entities from the rest of the body. However, there is a paradigm shift in this conception and oral health is now considered as a fundamental part of overall well-being. In recent years, the subject of oral-foci of infection has attained a resurgence in terms of systemic morbidities while limited observations denote the implication of chronic oral inflammation in the pathogenesis of eye diseases. Hitherto, there is a paucity for mechanistic insights underlying the reported link between periodontal disease (PD) and ocular comorbidities. In light of prevailing scientific evidence, this review article will focus on the understudied theme, that is, the impact of oral dysbiosis in the induction and/or progression of inflammatory eye diseases like diabetic retinopathy, scleritis, uveitis, glaucoma, age-related macular degeneration (AMD). Furthermore, the plausible mechanisms by which periodontal microbiota may trigger immune dysfunction in the Oro-optic-network and promote the development of PD-associated AMD have been discussed.

Association between Polygenic Risk Score and One-Year Outcomes Following As-Needed Aflibercept Therapy for Exudative Age-Related Macular Degeneration

We investigated whether polygenic risk score (PRS) was associated with one-year outcome of as-needed aflibercept therapy for exudative age-related macular degeneration (AMD), including AMD (n = 129) and polypoidal choroidal vasculopathy (n = 132). A total of 261 patients were treated with as-needed intravitreal aflibercept injection (IAI) after three monthly IAIs and the completion of a one-year follow-up. One hundred and seventy-two healthy volunteers served as controls. Genotyping of ARMS2 A69S (rs10490924), CFH I62V (rs800292), SKIV2L-C2-CFB (rs429608), C3 (rs2241394), ADAMTS-9 (rs6795735) and CETP (rs3764261) was performed for all participants. A total of 63 PRSs were quantified. There was a positive association between the PRS involving ARMS2, CFH, C3, and ADAMTS-9 and best-corrected visual acuity at twelve months (p = 0.046, multiple regression analysis). When comparing PRSs of patients requiring retreatment and of patients without retreatment, 35 PRSs were significantly greater in patients requiring retreatment than in patients without requiring retreatment, with the PRS involving ARMS2 and CFH being most significantly associated (p = 1.6 × 10⁻⁴). The number of additional injections was significantly associated with 40 PRSs and the PRS involving ARMS2 and CFH showed a most significant p-value (p = 2.42 × 10⁻⁶). Constructing a PRS using a combination with high-risk variants might be informative for predicting the response to IAI for exudative AMD.