Fundus changes in (type II) mesangiocapillary glomerulonephritis simulating drusen: a histopathological report

Giant retinal pigment epithelium tears with membranous nephropathy: a case report and literature review

BACKGROUND

Kidney and eye diseases may be closely linked. Tears of the retinal pigment epithelium (RPE) have been reported to be related to kidney diseases, such as IgA nephropathy and light-chain deposition disease. However, pigment epithelium tears associated with membranous nephropathy have not been reported or systematically analysed.

CASE PRESENTATION

A 68-year-old man presented with decreased right eye visual acuity. Optical coherence tomography (OCT) revealed cystic macular edema, localized serous detachment of the retina and loss of the outer retinal structure in the right eye and retinal pigment epithelium detachment (PED) combined with serous detachment of the retina in the left eye. Fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) revealed giant RPE tears in the right eye and exudative age-related macular degeneration in the left eye. The patient also suffered from severe membranous nephropathy-autoimmune glomerulonephritis. Renal biopsy immunofluorescence revealed a roughly granular pattern, with immunoglobulin G (IgA), immunoglobulin G (IgG), IgM, complement C3(Components 3), λ light chain and κ light chain subepithelial staining.

CONCLUSIONS

It is hypothesized that severe membranous nephropathy caused immune complex deposition on the surface of Bruch membrane, resulting in weakened adhesion between the RPE and Bruch membrane and impaired RPE pump function, combined with age-related macular degeneration, leading to giant RPE tears in the right eye. Close attention should be given to the ocular condition of patients with membranous nephropathy to facilitate timely treatment and avoid serious consequences.

Clearance of lipid droplets by chimeric autophagy-tethering compound ameliorates the age-related macular degeneration phenotype in mice lacking APOE

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness among the elderly, and there is currently no clinical treatment targeting the primary impairment of AMD. The earliest clinical hallmark of AMD is drusen, which are yellowish spots mainly composed of lipid droplets (LDs) accumulated under the retinal pigment epithelium (RPE). However, the potential pathogenic role of this excessive LD accumulation in AMD is yet to be determined, partially due to a lack of chemical tools to manipulate LDs specifically. Here, we employed our recently developed Lipid Droplets·AuTophagy Tethering Compounds (LD∙ATTECs) to degrade LDs and to evaluate its consequence on the AMD-like phenotypes in apoe-/- (apolipoprotein E; B6/JGpt-Apoeem1Cd82/Gpt) mouse model. apoe-/- mice fed with high-fat diet (apoe-/--HFD) exhibited excessive LD accumulation in the retina, particularly with AMD-like phenotypes including RPE degeneration, Bruch's membrane (BrM) thickening, drusen-like deposits, and photoreceptor dysfunction. LD·ATTEC treatment significantly cleared LDs in RPE/choroidal tissues without perturbing lipid synthesis-related proteins and rescued RPE degeneration and photoreceptor dysfunction in apoe-/--HFD mice. This observation implied a causal relationship between LD accumulation and AMD-relevant phenotypes. Mechanically, the apoe-/--HFD mice exhibited elevated oxidative stress and inflammatory signals, both of which were mitigated by the LD·ATTEC treatment. Collectively, this study demonstrated that LD accumulation was a trigger for the process of AMD and provided entry points for the treatment of the initial insult of AMD by degrading LDs.Abbreviations: AMD: age-related macular degeneration; APOE: apolipoprotein E; ATTECs: autophagy-tethering compounds; BODIPY: boron-dipyrromethene; BrM: Bruch's membrane; ERG: electroretinogram; HFD: high-fat diet; LD·ATTECs: Lipid Droplets·AuTophagy Tethering Compounds; LDs: lipid droplets; OA: oleic acid; OPL: outer plexiform layer; ROS: reactive oxygen species; RPE: retinal pigment epithelium.

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.

Bruch's Membrane: A Key Consideration with Complement-Based Therapies for Age-Related Macular Degeneration

The complement system is crucial for immune surveillance, providing the body's first line of defence against pathogens. However, an imbalance in its regulators can lead to inappropriate overactivation, resulting in diseases such as age-related macular degeneration (AMD), a leading cause of irreversible blindness globally affecting around 200 million people. Complement activation in AMD is believed to begin in the choriocapillaris, but it also plays a critical role in the subretinal and retinal pigment epithelium (RPE) spaces. Bruch's membrane (BrM) acts as a barrier between the retina/RPE and choroid, hindering complement protein diffusion. This impediment increases with age and AMD, leading to compartmentalisation of complement activation. In this review, we comprehensively examine the structure and function of BrM, including its age-related changes visible through in vivo imaging, and the consequences of complement dysfunction on AMD pathogenesis. We also explore the potential and limitations of various delivery routes (systemic, intravitreal, subretinal, and suprachoroidal) for safe and effective delivery of conventional and gene therapy-based complement inhibitors to treat AMD. Further research is needed to understand the diffusion of complement proteins across BrM and optimise therapeutic delivery to the retina.

Increased retinal drusen in IgA glomerulonephritis are further evidence for complement activation in disease pathogenesis

Drusen are retinal deposits comprising cell debris, immune material and complement that are characteristic of macular degeneration but also found in glomerulonephritis. This was a pilot cross-sectional study to determine how often drusen occurred in IgA glomerulonephritis and their clinical significance. Study participants underwent non-mydriatic retinal photography, and their deidentified retinal images were examined for drusen by two trained graders, who compared central drusen counts, counts ≥ 10 and drusen size with those of matched controls. The cohort comprised 122 individuals with IgA glomerulonephritis including 89 males (73%), 49 individuals (40%) of East Asian or Southern European ancestry, with an overall median age of 54 years (34-64), and median disease duration of 9 years (4-17). Thirty-nine (33%) had an eGFR < 60 ml/min/1.73 m² and 72 had previously reached kidney failure (61%). Overall mean drusen counts were higher in IgA glomerulonephritis (9 ± 27) than controls (2 ± 7, p < 0.001). Central counts ≥ 10 were also more common (OR = 3.31 (1.42-7.73, p = 0.006), and were associated with longer disease duration (p = 0.03) but not kidney failure (p = 0.31). Larger drusen were associated with more mesangial IgA staining (p = 0.004). Increased drusen counts were also present in IgA glomerulonephritis secondary to Crohn's disease but not with Henoch-Schonlein purpura. The finding of retinal drusen in IgA glomerulonephritis is consistent with complement activation and represents a model for better understanding glomerular immune deposition and a supporting argument for treatment with anti-complement therapies.

Structural Features of Patients with Drusen-like Deposits and Systemic Lupus Erythematosus

Background: The relevance of drusen-like deposits (DLD) in patients with systemic lupus erythematosus (SLE) is to a large extent uncertain. Their genesis is proposed to be correlated to immune-complex and complement depositions in the framework of SLE. The intention of this study was to determine potential morphological differences in the choroid and retina as well as potential microvascular changes comparing two cohorts of SLE patients divergent in the presence or absence of DLD using multimodal imaging. Methods: Both eyes of 16 SLE patients with DLD were compared to an age- and sex-matched control-group consisting of 16 SLE patients without detectable DLD. Both cohorts were treated with hydroxychloroquine (HCQ) and did not differ in the treatment duration or dosage. Using spectral-domain optical coherence tomography (SD-OCT) choroidal volume measures, choroidal vascularity indices (CVI) and retinal layer segmentation was performed and compared. In addition, by the exploitation of optical coherence tomography angiography vascular density, perfusion density of superficial and deep retinal capillary plexuses and the choriocapillaris were analyzed. For the choroidal OCT-scans, a subset of 51 healthy individuals served as a reference-group. Results: CVI measures revealed a significant reduction in eyes with DLD compared to healthy controls (0.56 (0.54−0.59) versus 0.58 (0.57−0.59) (p = 0.018) and 0.56 (0.54−0.58) versus 0.58 (0.57−0.60) (p < 0.001)). The photoreceptor cell layer presented significant thinning in both eyes of subjects with DLD compared to control subjects without DLD (68.8 ± 7.7 µm vs. 77.1 ± 7.3 µm for right eyes, p = 0.008, and 66.5 ± 10.5 µm vs. 76.1 ± 6.3 µm for left eyes, p = 0.011). OCTA scans revealed no significant changes, yet there could be observed numerically lower values in the capillary plexuses of the retina in eyes with DLD than in eyes without DLD. Conclusions: Our results illustrated significant alterations in the choroidal and retinal analyzes, suggesting a correlation between DLD and the progression of inflammatory processes in the course of SLE leading to retinal degeneration. For this reason, DLD could serve as a biomarker for a more active state of disease.

Retinal drusen in glomerulonephritis with or without immune deposits suggest systemic complement activation in disease pathogenesis

Retinal drusen are characteristic of macular degeneration and complement activation, but also occur in C3, lupus and IgA nephropathy. This cross-sectional observational study compared drusen counts in different forms of glomerulonephritis. Consecutive individuals with glomerulonephritis attending a general renal or transplant clinic underwent retinal imaging with a non-mydriatic camera. Drusen were counted in deidentified images by trained graders, compared with matched hospital patients, and correlated with clinical features. Eighty-four individuals with glomerulonephritis had a mean drusen count of 10 ± 27 compared with 3 ± 8 in hospital controls (p = 0.007). Fourteen individuals with glomerulonephritis (17%) and 4 hospital controls (4/49, 8%) had increased drusen counts (≥ 10) (p = 0.20). Increased drusen counts ≥ 10 were present in 13 (13/63, 21%)  of those with glomerulonephritis and immune deposits [membranous (n = 8), antiglomerular basement membrane nephritis (n = 6), FSGS (n = 49)], and one of the 21 (5%) with glomerulonephritis without immune deposits [ANCA-associated (n = 15), minimal change disease (n = 6)]. In antibody-mediated glomerulonephritis (n = 14), mean drusen counts were 2 ± 3 in individuals with normal kidney function, 16 ± 41 with impaired function and 5 ± 7 with kidney failure . Mean counts were 24 ± 56 in individuals with glomerular IgG deposits and 1 ± 1 in those without (p = 0.76), and 23 ± 60 with complement deposits and 4 ± 8 in those without. Drusen counts were also less in immunosuppressed individuals (p = 0.049). The demonstration of retinal drusen in some forms of glomerulonephritis is consistent with systemic complement activation, and suggests that treatment targeting the complement pathways is worthwhile.

Retinal drusen are more common and larger in SLE with renal impairment

Introduction

Complement has been implicated in systemic lupus erythematosus (SLE) pathogenesis on the basis of the associations with inherited complement defects and genome-wide association study risk alleles, glomerular deposits, reduced serum levels, and occasional reports of retinal drusen. This study examined drusen in SLE and their clinical significance.

Methods

This cross-sectional observational study compared individuals with SLE recruited from renal and rheumatology clinics with hospital controls. Participants were reviewed for clinical features and underwent imaging with a nonmydriatic retinal camera. Deidentified images were examined by 2 trained graders for drusen number and size using a grid overlay.

Results

The cohort with SLE (n = 65) comprised 55 women (85%) and 10 men (15%) with a median age of 47 years (interquartile range 35–59), where 23 (35%) were of southern European or Asian ancestry, and 32 (49%) had biopsy-proven lupus nephritis. Individuals with SLE had higher mean drusen numbers than controls (27 ± 60, 3 ± 9, respectively, P = 0.001), more drusen counts ≥10 (31, 48% and 3, 5%, respectively, P < 0.001), and more medium-large drusen (14, 22% and 3, 5%, respectively, P < 0.001). In SLE, mean drusen counts were higher, and drusen were larger, with an estimated glomerular filtration rate (eGFR) <90 ml/min per 1.73 m² (P = 0.02, P = 0.02, respectively) or class IV nephritis (P = 0.03, P = 0.02).

Conclusion

Drusen composition resembles that of glomerular immune deposits. CFH controls complement activation in the extracellular matrix and CFH risk variants are shared by drusen in macular degeneration and by SLE. CFH represents a possible treatment target for SLE especially with renal impairment.

Retinal findings in glomerulonephritis

The complement system is part of the innate immune system activated by three distinct pathways: classical, lectin and alternative. It is also involved in retinal development and homoeostasis. Dense deposit disease is a rare renal disease associated with mutations in Complement factor H and overactivity of the alternative complement pathway. As well as glomerulonephritis, many affected individuals have retinal drusen and may be at risk of vision loss due to macular atrophy or choroidal neovascularisation. We discuss the reclassification of dense deposit disease as a type of C3 glomerulonephropathy, and hypothesise on the mechanisms of retinal abnormalities. Drusen have also been described in individuals with other types of glomerulonephritis involving abnormalities of the classical (membranoproliferative glomerulonephritis type 1) or lectin (IgA nephropathy, lupus nephritis) complement pathways. Although drusen are found in abnormalities of all three complement pathways, the age at onset, aetiology, and the threat to vision differs. This review describes drusen and other retinal abnormalities associated with the glomerulonephritides due to abnormal activation in each of the three complement activation pathways, and provides the first report of drusen occurring in a patient with the recently reclassified C3 glomerulonephritis with homozygous variant V62I in complement factor H. Optometric management of young patients presenting with retinal drusen is discussed, and complement-based therapies for visual loss are reviewed.

Increased risk for central serous chorioretinopathy in nephrotic syndrome patients: A population-based cohort study

BACKGROUND

Nephrotic syndrome (NS) is characterized by various etiologies that damage the glomerulus. Central serous chorioretinopathy (CSCR) is a retinal disease characterized by neurosensory detachment of the retina. Several case reports have described the relationship between both. Therefore, we try to analyze the epidemiological associations between NS and CSCR using the National Health Insurance Research Database in Taiwan.

METHODS

Data spanning 14 years were extracted from the National Health Insurance Research Database and sub-grouped. The variables were analyzed using Pearson's chi-squared test and Fisher's exact test. The risk factors for disease development with or without comorbidities were examined using an adjusted hazard ratio (aHR). Kaplan-Meier analysis was performed to evaluate the cumulative incidence of CSCR with or without NS.

RESULTS

A total of 14 794 patients with NS and 14 794 matched controls without NS were enrolled in this cohort study. The incidence rate of CSCR was higher in the study cohort than in the control cohort (aHR = 3.349, p < 0.001). The overall incidence of CSCR was 44.51 per 100 000 person-years in the study cohort and 33.39 per 100 000 person-years in the control cohort. In both groups, CSCR occurred more frequently in males than in females. Patients aged 40-49, 50-59, and ≥60 years in the study cohort had a significantly higher risk of developing CSCR than those in the control cohort (aHR = 3.445, 5.421, and 4.957, all p < 0.001). NS patient with a 4-week history of steroid usage has a higher risk of developing CSCR (aHR = 2.010, p < 0.001).

CONCLUSION

Our data showed that patients with NS have an increased risk of developing subsequent CSCR. Physician should routinely refer their NS patients to ophthalmologist for ophthalmic evaluation. This is the first nationwide epidemiological study reporting the association between these two diseases. Further studies are needed to clarify this relationship.

Characterization of Calcium Phosphate Spherical Particles in the Subretinal Pigment Epithelium-Basal Lamina Space in Aged Human Eyes

Purpose

Micrometer-sized spherules formed of hydroxyapatite or whitlockite were identified within extracellular deposits that accumulate in the space between the basal lamina (BL) of retinal pigment epithelium (RPE) and the inner collagenous layer of Bruch's membrane (sub-RPE-BL space). This investigation aimed to characterize the morphologic features, structure, and distribution of these spherules in aged human eyes with and without clinical indications of age-related macular degeneration (AMD).

Design

Experimental study.

Participants

Five human eyes with varying degrees of sub-RPE-BL deposits were obtained from the University College London Institute of Ophthalmology and Moorfield's Eye Hospital Tissue Repository or the Advancing Sight Network. Two eyes were reported as having clinical indications of AMD (age, 76-87 years), whereas 3 were considered healthy (age, 69-91 years).

Methods

Cadaveric eyes with sub-RPE-BL deposits were embedded in paraffin wax and sectioned to a thickness of 4-10 μm. Spherules were identified and characterized using high-resolution scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy, and time-of-flight secondary ion mass spectroscopy.

Main Outcome Measures

High-resolution scanning electron micrographs of spherules, the size-frequency distribution of spherules including average diameter, and the distribution of particles across the central-peripheral axis. Elemental maps and time-of-flight secondary ion mass spectra also were obtained.

Results

The precipitation of spherules is ubiquitous across the central, mid-peripheral, and far-peripheral axis in aged human eyes. No significant difference was found in the frequency of spherules along this axis. However, statistical analysis indicated that spherules exhibited significantly different sizes in these regions. In-depth analysis revealed that spherules in the sub-RPE-BL space of eyes with clinical signs of AMD were significantly larger (median diameter, 1.64 μm) than those in healthy aged eyes (median diameter, 1.16 μm). Finally, spherules showed great variation in surface topography and internal structure.

Conclusions

The precipitation of spherules in the sub-RPE-BL space is ubiquitous across the central-peripheral axis in aged human eyes. However, a marked difference exists in the size and frequency of spherules in eyes with clinical signs of AMD compared to those without, suggesting that the size and frequency of spherules may be associated with AMD.

Pathogenic Variants in the Genes Affected in Alport Syndrome (COL4A3-COL4A5) and Their Association With Other Kidney Conditions: A Review

Massively Parallel Sequencing identifies pathogenic variants in the genes affected in Alport syndrome (COL4A3 - COL4A5) in up to 30 % of individuals with focal and segmental glomerulosclerosis (FSGS), 10 % of those with kidney failure of unknown cause and 20 % with familial IgA glomerulonephritis. FSGS associated with COL4A3 - COL4A5 variants is usually present by kidney failure onset and may develop because the abnormal glomerular membranes result in podocyte loss and secondary hyperfiltration. The association of COL4A3 - COL4A5 variants with kidney failure or IgA glomerulonephritis may be coincidental and not pathogenic. However, since some of these variants occur more often than they should by chance, some may be pathogenic. COL4A3 - COL4A5 variants are sometimes also found in cystic kidney diseases after autosomal dominant polycystic kidney disease (ADPKD) has been excluded. COL4A3 - COL4A5 variants should be suspected in individuals with FSGS, kidney failure of unknown cause, or familial IgA glomerulonephritis, especially where there is persistent haematuria, and a family history of haematuria or kidney failure.

Revisiting the role of factor H in age-related macular degeneration: Insights from complement-mediated renal disease and rare genetic variants

Ophthalmologists are long familiar with the eye showing signs of systemic disease, but the association between age-related macular degeneration and abnormal complement activation, common to several renal disorders, has only recently been elucidated. Although complement activation products were identified in drusen almost three decades ago, it was not until the early 21st century that a single-nucleotide polymorphism in the complement factor H gene was identified as a major heritable determinant of age-related macular degeneration, galvanizing global efforts to unravel the pathogenesis of this common disease. Advances in proteomic analyses and familial aggregation studies have revealed distinctive clinical phenotypes segregated by the functional effects of common and rare genetic variants on the mature protein and its splice variant, factor H-like protein 1. The predominance of loss-of-function, N-terminal mutations implicate age-related macular degeneration as a disease of general complement dysregulation, offering several therapeutic avenues for its modulation. Here, we explore the molecular impact of these mutations/polymorphisms on the ability of variant factor H/factor H-like protein 1 to localize to polyanions, pentraxins, proinflammatory triggers, and cell surfaces across ocular and renal tissues and exert its multimodal regulatory functions and their clinical implications. Finally, we critically evaluate key therapeutic and diagnostic efforts in this rapidly evolving field.

Choroidal Neovascularization in Primary Membranous Nephropathy

Patient: Male, 61-year-old

Final Diagnosis: Choroidal neovascularization

Symptoms: Decrease in the visual acuity • metamorphopsia

Medication:—

Clinical Procedure: —

Specialty: Nephrology • Ophthalmology

EYES WITH SUBRETINAL DRUSENOID DEPOSITS AND NO DRUSEN: Progression of Macular Findings

PURPOSE

To investigate the macular changes over time in eyes containing subretinal drusenoid deposits (also known as pseudodrusen) with no drusen >63 µm.

METHODS

A consecutive series of patients were examined with color fundus photography, optical coherence tomography, and autofluorescence imaging with fluorescein angiography used as necessary. Exclusionary criteria included macular neovascularization, history of retinal surgery, pseudoxanthoma elasticum, and drusen >63 µm.

RESULTS

There were 85 eyes of 54 patients. The mean age at baseline was 83.6 (±7.8) years, and there were 17 men. The mean follow-up was 5.0 (±2.9) years. At initial optical coherence tomography examination, 12 eyes had extrafoveal atrophy and 17 eyes had vitelliform deposits, which were yellowish white subretinal collections that showed intense hyperautofluorescence. During follow-up, 11 eyes lost vitelliform material. After the disappearance of small deposits, focal hyperpigmentation remained. Loss of larger deposits was associated with noteworthy sequela; six developed subfoveal atrophy and one macular neovascularization close to regressing vitelliform material. Subfoveal geographic atrophy developed in four other eyes without vitelliform material by extension from areas of extrafoveal atrophy. Macular neovascularization developed in seven eyes over follow-up. The CFH Y402H and ARMS2 A69S allele frequencies were 57% and 48.9%, respectively, which is similar to a group of age-related macular degeneration controls. One patient had a novel PRPH2 mutation, but did not have a vitelliform deposit; the remainder had a normal PRPH2 and BEST1 coding sequences.

CONCLUSION

Eyes with subretinal drusenoid deposits and no drusen >63 mm have significant risk for the development of both neovascularization and geographic atrophy, the fundamental components of late age-related macular degeneration. An intermediate step in some eyes was the development of a vitelliform deposit, an entity not traditionally associated with age-related macular degeneration, but in these patients, the material seemed to be an important component of the disease pathophysiology. This vitelliform deposit was not associated with genetic markers for pattern dystrophy or Best disease.

The story of complement factor I

Factor I was first discovered in 1966. Its importance became apparent with the description of the original Factor I deficient patient in Boston in 1967. This patient presented with a hyperactive alternative complement pathway resulting in secondary complement deficiency due to continuous complement consumption. On the basis of these findings, the mechanism of the alternative pathway was worked out. In 1975, the surprise finding was made that elevating levels of Factor I in plasma down-regulated the alternative pathway. Attempts to exploit this finding for clinical use had a long and frustrating history and it was not until 2019 that the first patient was treated with the gene therapy vector for age related macular degeneration by Professor Sir Robert MacLaren in Oxford. This review follows the long and contorted course from initial observations to clinical use of complement Factor I.

Retinal Basal Laminar Deposits in Complement fH/fP Mouse Model of Dense Deposit Disease

Purpose

Dense deposit disease (DDD) is caused by dysregulation of the alternative pathway of the complement cascade and characterized by electron-dense deposits in the kidney glomerular basement membrane (GBM) and drusen in Bruch's membrane (BrM). Complement factor H (fH) and factor properdin (fP) regulate complement activation; fH inhibits alternative pathway (AP) activation, whereas fP promotes it. We report pathologic changes in eyes of an fH and fP double-mutant mouse, which we previously showed have dense deposits in the GBM and early mortality from nephropathy.

Methods

fH^m/m, fP^−/−, and fH^m/m/fP^−/− mice were generated on a C57BL/6–129J background. Fundus imaging at 8 weeks of age was followed by analysis via light and electron microscopy. Retinal function was assessed by electroretinography (ERG). Complement levels and localization were tested by immunohistochemistry and ELISA. Retinas of fH^m/m/fP^−/− mice treated with intraperitoneal injections of an anti-C5 antibody were compared to those of age- and genotype-matched mice injected with an isotype control antibody.

Results

fH^m/m/fP^−/− mice suffered early-onset retinal hypopigmented spots detected using in vivo retinal photography, and histologic examination showed basal laminar deposits (BLamD), degeneration of the photoreceptors, and RPE vacuolization. ERG showed diminished retinal function. The anti-C5 antibody was retina-protective.

Conclusions

This unique mouse represents a new model of complement-mediated rapid-onset DDD, and could be useful in exploring the pathologic changes associated with BLamD in age-related macular degeneration.

Choroid thickness profile in patients with lupus nephritis

BACKGROUND

Choroidopathy is a rare manifestation of systemic lupus erythematosus (SLE). This entity is associated with active phases of severe SLE and it is frequently accompanied by acute kidney failure, central nervous system involvement and coagulopathy.

PURPOSE

To evaluate the choroid thickness of patients with lupus nephritis (LN) without choroidopathy, and to compare this with that of age-matched SLE patients without LN and healthy control subjects.

STUDY DESIGN

Cross-sectional case control study.

MATERIAL AND METHODS

Fifteen women with LN in remission phase (study group), 15 women with SLE in remission without LN (SLE control group), and 15 healthy women (healthy control group), without ocular diseases or significant refractive error, were recruited. Full ophthalmological examination and a macular optical coherence tomography in enhanced depth imaging mode were performed. The choroid thickness was measured at nine macular points and six lines of mean choroidal thickness were determined. A comparative analysis between the three groups was performed using the one-way ANOVA test and the paired t-test. The choroid thickness of patients under corticotherapy was also compared to that of patients without corticotherapy. Additionally, the correlation between choroid thickness and disease duration was evaluated using the Pearson analysis.

RESULTS

The mean macular choroidal thickness was 295.73 ± 67.62 μm in the study group, 233.34 ± 41.01 µm in the SLE control group, and 240.98 ± 37.93 μm in the control group ( p = 0.00006 and p = 0.0003, respectively). Additionally, the choroid thickness was significantly thicker than in the SLE and healthy control groups at the foveal ( p = 0.004 and p < 0.000), nasal ( p < 0.000 and p = 0.001), superior ( p = 0.002 and p < 0.000) and inferior ( p < 0.000 and p = 0.001) mean lines. The choroidal thickness in this group was not associated with the duration of the disease. The subgroup of patients with LN under corticotherapy did not reveal a significantly different choroidal thickness.

CONCLUSION

This study suggests a relationship between LN and choroidal changes, which may represent an increased risk for choroidopathy in these patients. Choroid thickening was not related with the duration of the disease. This thickening may be correlated with histopathological changes similar to those occurring in kidney glomeruli.

On the origin of proteins in human drusen: The meet, greet and stick hypothesis

Retinal drusen formation is not only a clinical hallmark for the development of age-related macular degeneration (AMD) but also for other disorders, such as Alzheimer's disease and renal diseases. The initiation and growth of drusen is poorly understood. Attention has focused on lipids and minerals, but relatively little is known about the origin of drusen-associated proteins and how they are retained in the space between the basal lamina of the retinal pigment epithelium and the inner collagenous layer space (sub-RPE-BL space). While some authors suggested that drusen proteins are mainly derived from cellular debris from processed photoreceptor outer segments and the RPE, others suggest a choroidal cell or blood origin. Here, we reviewed and supplemented the existing literature on the molecular composition of the retina/choroid complex, to gain a more complete understanding of the sources of proteins in drusen. These "drusenomics" studies showed that a considerable proportion of currently identified drusen proteins is uniquely originating from the blood. A smaller, but still large fraction of drusen proteins comes from both blood and/or RPE. Only a small proportion of drusen proteins is uniquely derived from the photoreceptors or choroid. We next evaluated how drusen components may "meet, greet and stick" to each other and/or to structures like hydroxyapatite spherules to form macroscopic deposits in the sub-RPE-BL space. Finally, we discuss implications of our findings with respect to the previously proposed homology between drusenogenesis in AMD and plaque formation in atherosclerosis.

A long history of dense deposit disease

BACKGROUND

Dense Deposit Disease is a rare condition affecting the Bruch's membrane and the glomerular basement membrane. We report the progression of the ocular manifestations over a 30 year follow up period, longer than any previous report.

CASE PRESENTATION

A 44 year old male presented with pigmentary changes at the macula noted by his optician. Best corrected visual acuity at presentation was good in both eyes. Fundoscopy showed pigmentary changes and drusen, and investigation using intravenous fundus fluorescein angiography did not demonstrate any choroidal neovascular membrane. The patient subsequently developed renal failure and received a dual renal transplant. The transplanted kidneys also failed over the coming year. The patient's vision gradually deteriorated and comparison between the images in 2010 and 1985 demonstrated a clear progression of the macula changes. Optical coherence tomography showed multiple subretinal hyper reflective drusenoid deposits. These deposits were also noted to be autofluorescent on blue auto-fluorescence. The young age at presentation of drusen, combined with the history of recurrent kidney failure and progression of subretinal deposits led to a diagnosis of dense deposit disease.

CONCLUSIONS

Dense deposit disease is a rare condition affecting Bruch's membrane, but should be considered in the differential diagnosis of any patient under the age of 50 years presenting with drusen.

Sequential Observation of Fundus Changes in Patients with Long Standing Membranoproliferative Glomerulonephritis Type II (MPGN type II)

Specific fundus changes have been reported in patients with membranoproliferative glomerulonephritis type II (MPGN type II). We studied the clinical course of this retinopathy in four patients who all had a long follow-up with several fundus examinations. Sequential observation was indicative of a slow progression of the retinopathy. Most eyes maintained in the chronic stages a nearly normal visual acuity, and a full visual field despite the existence of marked drusen and atrophic changes. The prognosis however must be somewhat guarded, since choroidal neovascularization developed in three eyes and caused bilateral severe visual loss in one patient.

Fundus changes in type III membranoproliferative glomerulonephritis: a case report

Background

Membranoproliferative glomerulonephritis (MPGN) is characterized by mesangial cell proliferation and is classified into types I, II and III based on structural changes in the glomerular capillary walls. The drusen-like deposits of MPGN type II have been studied, but the fundus changes in MPGN type III have yet to be clarified. We report a case of MPGN type III with multiple deposits in the retinal pigment epithelium (RPE).

Case presentation

A 40-year-old Japanese woman with MPGN type III developed numerous yellow-white patches in the central macula of both eyes. Optical coherence tomography (OCT) showed deposits between the RPE and Bruch’s membrane. Fluorescein angiography showed choroidal neovascularization (CNV) and OCT confirmed it as type 1 (sub RPE) CNV with fibrin tissue and subretinal fluid in the right eye. After 12 months, the CNV and subretinal fluid resolved spontaneously but the RPE deposits remained in both eyes. Her final visual acuity was 20/20 in the right eye and 20/16 in the left eye.

Conclusion

We report a case of MPGN type III with multiple deposits in the RPE and CNV, suggesting that various fundus changes occur in MPGN type III and careful fundus follow-up is necessary to prevent vision loss.

Retinal findings in membranoproliferative glomerulonephritis

Purpose

To assess the evolution of retinal findings in patients with membranoproliferative glomerulonephritis (MPGN) by funduscopy, intravenous fluorescein angiography and optical coherence tomography.

Observations

Three women and one man were followed for a period of 1.5–37 years. Four patients (8 eyes) had drusen detected at first fundus exam at age 24, 29, 50 and 55. Three patients (6 eyes) had diffuse thickening of Bruch's membrane, and two patients (3 eyes) had detachment of the retinal pigment epithelium with serous retinal detachment. Drusen tended to widen over a period of 10-year follow-up in one case.

Conclusions and importance

Drusen remain the ocular stigmata for MPGN occuring at an early age. The retinal disease is progressive with gradual thickening of Bruch's membrane and occurrence of retinal pigment epithelium detachment.

Benign Yellow Dot Maculopathy: A New Macular Phenotype

PURPOSE

To describe a novel macular phenotype that is associated with normal visual function.

DESIGN

Retrospective, observational case series.

PARTICIPANTS

Thirty-six affected individuals from 23 unrelated families.

METHODS

This was a retrospective study of patients who had a characteristic macular phenotype. Subjects underwent a full ocular examination, electrophysiologic studies, spectral-domain optical coherence tomography (OCT), and fundus autofluorescence imaging. Genomic analyses were performed using haplotype sharing analysis and whole-exome sequencing.

MAIN OUTCOME MEASURES

Visual acuity, retinal features, electroretinography, and whole-exome sequencing.

RESULTS

Twenty-six of 36 subjects were female. The median age of subjects at presentation was 15 years (range, 5-59 years). The majority of subjects were asymptomatic and presented after a routine eye examination (22/36 subjects) or after screening because of a positive family history (13/36 subjects) or by another ophthalmologist (1/36 subjects). Of the 3 symptomatic subjects, 2 had reduced visual acuity secondary to nonorganic visual loss and bilateral ametropic amblyopia with strabismus. Visual acuity was 0.18 logarithm of the minimum angle of resolution (logMAR) or better in 30 of 33 subjects. Color vision was normal in all subjects tested, except for the subject with nonorganic visual loss. All subjects had bilateral symmetric multiple yellow dots at the macula. In the majority of subjects, these were evenly distributed throughout the fovea, but in 9 subjects they were concentrated in the nasal parafoveal area. The dots were hyperautofluorescent on fundus autofluorescence imaging. The OCT imaging was generally normal, but in 6 subjects subtle irregularities at the inner segment ellipsoid band were seen. Electrophysiologic studies identified normal macular function in 17 of 19 subjects and normal full-field retinal function in all subjects. Whole-exome analysis across 3 unrelated families found no pathogenic variants in known macular dystrophy genes. Haplotype sharing analysis in 1 family excluded linkage with the North Carolina macular dystrophy (MCDR1) locus.

CONCLUSIONS

A new retinal phenotype is described, which is characterized by bilateral multiple early-onset yellow dots at the macula. Visual function is normal, and the condition is nonprogressive. In familial cases, the phenotype seems to be inherited in an autosomal dominant manner, but a causative gene is yet to be ascertained.

Multimodal imaging of membranoproliferative glomerulonephritis type II

To report the fundus findings on multimodal imaging of a membranoproliferative glomerulonephritis type II (MPGNII) patient. A 41-year-old woman had a medical history of renal transplantation for MPGNII 5 years prior to presentation to our clinic for ophthalmic examination. Fundus examination showed macular retinal pigment epithelial changes and large peripapillary atrophy in the right eye, and yellowish bilateral drusen-like deposits peripherally. Fundus fluorescein angiography and indocyanine green angiography revealed multifocal hyperfluorescence in the peripheral retina with accompanying deposits. A hyperautofluorescence pattern was seen in the fundus autofluorescence (FAF) images of the deposits. Spectral domain optical coherence tomography (SD-OCT) scans of the drusen-like material showed retinal pigment epithelium (RPE) elevations with moderate hyperreflectivity underneath. Multiple imaging modalities of the posterior segment can provide detailed information about the ocular involvement of MPGNII and help us to confirm the diagnosis and to follow the lesions.

Atypical hemolytic uremic syndrome and C3 glomerulopathy: conclusions from a "Kidney Disease: Improving Global Outcomes" (KDIGO) Controversies Conference

In both atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy (C3G) complement plays a primary role in disease pathogenesis. Herein we report the outcome of a 2015 Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference where key issues in the management of these 2 diseases were considered by a global panel of experts. Areas addressed included renal pathology, clinical phenotype and assessment, genetic drivers of disease, acquired drivers of disease, and treatment strategies. In order to help guide clinicians who are caring for such patients, recommendations for best treatment strategies were discussed at length, providing the evidence base underpinning current treatment options. Knowledge gaps were identified and a prioritized research agenda was proposed to resolve outstanding controversial issues.

Manifestations of Complement-Mediated and Immune Complex-Mediated Membranoproliferative Glomerulonephritis: A Comparative Consecutive Series

PURPOSE

Membranoproliferative glomerulonephritis (MPGN) recently was reclassified to reflect the underlying cause as a complement-mediated and immune complex-mediated disease. This classification is based on renal biopsy immunofluorescence examination, making the former electron-microscopy classification obsolete. In this report, we describe related eye findings in patients with MPGN based on the new classification.

DESIGN

Retrospective case series.

PARTICIPANTS

All Mayo Clinic Rochester patients with pathology-confirmed complement- and immune complex-mediated MPGN who had available ophthalmology records from 1997 through 2014 were included in this study.

METHODS

The medical and pathologic records of patients with MPGN and eye examination results were reviewed from years 1997 through 2014.

MAIN OUTCOME MEASURES

The number of patients and the number of eyes with MPGN-related pathologic features were examined. Visual acuity also was considered.

RESULTS

There were 23 patients with complement-mediated MPGN and available eye examination results. Of these, 9 patients (39%) and 17 eyes (37%) had retinal pathologic features that likely were related to the same underlying pathophysiologic process as their renal disease. Five patients (22%) and 6 eyes (13%) had significant vision loss. There were 23 patients with immune complex-mediated MPGN and available eye examination results. Only 2 (9%) of these patients (4 eyes) had retinal pathologic features that potentially could be related to the same underlying pathophysiologic process as their renal disease, and neither had vision loss.

CONCLUSIONS

Retinal abnormalities are more prominent among patients with complement-mediated MPGN when compared with patients with immune complex-mediated MPGN. It is critical for ophthalmologists to recognize the updated MPGN classification system, and all patients with complement-mediated MPGN require screening eye examinations.

Overview of C3 Glomerulopathy

C3 glomerulopathy is an umbrella term, which includes several rare forms of glomerulonephritis (GN) with underlying defects in the alternate complement cascade. A common histological feature noted in all these GN is dominant C3 deposition in the glomerulus. In this review, we will provide an overview of the complement system as well as mediators, with an introduction to pharmaceutical agents that can alter the pathway.

SHEDDING LIGHT ON FUNDUS DRUSEN ASSOCIATED WITH MEMBRANOPROLIFERATIVE GLOMERULONEPHRITIS: BREAKING STEREOTYPES OF TYPES I, II, AND III

PURPOSE

Membranoproliferative glomerulonephritis (MPGN) classification has been changed from purely anatomic to molecular. This report describes two cases of MPGN with associated drusen that exemplify the importance of this change and the need for ophthalmologists to understand it.

METHODS

The medical and pathologic records of two patients with MPGN and drusen were examined.

RESULTS

Two patients with MPGN and risk-associated alleles of complement factor H were found to have drusen. In one case, the process led to severe visual impairment. Based on anatomic classification, one patient had MPGN Type I and the other had MPGN Type III. However, both patients had renal biopsy findings classic for C3 glomerulonephritis and the same genetic abnormality (risk-associated alleles of complement factor H).

CONCLUSION

The association of MPGN and drusen needs to be reevaluated. Previously only recognized in association with Type II MPGN, drusen have been demonstrated in 2 patients with C3 glomerulonephritis in this report. These drusen are likely the result of complement pathway abnormalities. The authors propose a new nomenclature in the ophthalmic literature to classify pathology as immune complex-mediated or complement-mediated rather than solely by the electron microscopy findings. This nomenclature will better characterize the underlying genetic abnormalities and pathophysiology of these disease processes.

Complement Activation and Inhibition in Retinal Diseases

Within the past several decades, a brigade of dedicated researchers from around the world has provided essential insights into the critical niche of immune-mediated inflammation in the pathogenesis of age-related macular degeneration (AMD). Yet, the question has lingered as to whether disease-initiating events are more or less dependent on isolated immune-related responses, unimpeded inflammation, endogenous pathways of age-related cell senescence and oxidative stress, or any of the other numerous molecular derangements that have been identified in the natural history of AMD. There is now an abundant cache of data signifying immune system activation as an impetus in the pathogenesis of this devastating condition. Furthermore, recent rigorous investigations have revealed multiple inciting factors, including several important complement-activating components, thus creating a new array of disease-modulating targets for the research and development of molecular therapeutic interventions. While the precise in vivo effects of complement activation and inhibition in the progression and treatment of AMD remain to be determined, ongoing clinical trials of the first generation of complement-targeted therapeutics are hoped to yield critical data on the contribution of this pathway to the disease process.

High-speed ultrahigh-resolution OCT of Bruch's membrane in membranoproliferative glomerulonephritis type 2

Membranoproliferative glomerulonephritis (MPGN) type 2 is characterized by electron-dense deposits in the glomerular basement membrane and drusen-like deposits in Bruch's membrane. Over time, atrophic changes in the retina and retinal pigment epithelium occur, which can progress to choroidal neovascularization (CNV). This report describes a patient with MPGN type 2 who developed progressive loss of vision secondary to CNV. High-speed ultrahigh-resolution optical coherence tomography (UHR-OCT) showed an irregular Bruch's membrane that measured 10 μm beneath the foveal center. High-speed UHR-OCT can potentially be used to analyze Bruch's membrane in secondary ocular manifestations of diseases such as MPGN type 2 and primary retinal diseases such as age-related macular degeneration.

Posterior segment findings in a patient with immunotactoid glomerulonephritis

PURPOSE

To present a case with posterior segment findings in a patient with cloudy corneas secondary to immunotactoid glomerulonephritis (ITG).

METHODS

A 57-year-old female was known to have bilateral cloudy corneas diagnosed 12 years ago secondary to immunotactoid glomerulonephritis. Clinically, fundus examination was difficult to visualise due to the density of her corneal opacities.

RESULTS

B-scan ultrasound revealed significant retino-choroidal & non-inflammatory scleral thickening. The macula also showed signs of thickening in both eyes. Optical coherence tomography (OCT) showed thinning of the inner retinal layers and significant choroidal folds in both eyes. Electrodiagnostic tests (EDT) concluded loss of retinal ganglion cells with preservation of retinal function in both eyes.

CONCLUSION

This case widens the spectrum of findings seen in patients diagnosed with Immunotactoid Glomerulonephritis and alerts us to undertake detailed posterior segment examination where possible. Ocular coherence tomography (OCT) and B-scan ultrasonography are important adjuvants to help assess the posterior segment in patients with corneal opacities secondary to ITG.

Current concepts in C3 glomerulopathy

Complement component 3 glomerulopathy (C3G) is a recently defined entity comprising of dense deposit disease and C3 glomerulonephritis. The key histological feature is the presence of isolated C3 deposits without immunoglobulins. Often masqueradng as some of the common glomerulonephritides this is a prototype disorder occurring from dysregulated alternate complement pathway with recently identified genetic defects and autoantibodies. We review the pathophysiology, clinical features, and diagnostic and treatment strategies.

Is renal function associated with early age-related macular degeneration?

PURPOSE

Age-related macular degeneration (AMD) and chronic kidney disease both involve immune dysregulation and may share underlying pathophysiologic changes to systemic homeostasis. Hence, we aim to evaluate associations between impaired kidney function and early AMD, in a search for urinary biomarkers for AMD.

METHODS

A population-based, cross-sectional analysis of persons aged 45 to 84 years was conducted with renal function measured using serum creatinine and cystatin C levels and the estimated glomerular filtration rate (eGFR) calculated. Age-related macular degeneration status was ascertained from retinal photographs.

RESULTS

Of 5874 participants, 221 had early AMD. High serum cystatin C and low eGFR (≤60 ml/min/1.73 m) were not associated with early AMD in our multivariate analyses. Among normotensive persons, however, highest versus other deciles of cystatin C were associated with an increased prevalence of early AMD (odds ratio, 1.80; 95% confidence interval, 1.00 to 3.23).

CONCLUSIONS

Results could not confirm an association between kidney function and early AMD. The borderline association between cystatin C and early AMD in normotensive persons require further verification.

Ocular complications after kidney transplantation: a case report and review of literature

Membranoproliferative glomerulonephritis type II (MPGN II), also known as a dense deposit disease, is a chronic progressive kidney disease that often progresses to end-stage renal disease within 10 years. Most patients also have multiple subretinal white spots or drusen-like deposits that are histopathologically identical to the glomerular basement membrane deposits. The purpose is to determine ocular findings in a patient with MPGN II before and after renal transplantation and to correlate them with clinical characteristics related to transplantation and review of literature. We present a case of a 45-year-old female with MPGN II who developed bilateral serous retinal detachment and retinal hemorrhages in the left eye, which appeared 6 months after a renal transplant. Ocular complications in our case, with the exception on the retina, were present at the cornea and iris. Changes to the eyes were independent of the renal disease, because there was no recurrence of MPGN II on the renal graft.

Dense deposit disease and C3 glomerulopathy

C3 glomerulopathy refers to those renal lesions characterized histologically by predominant C3 accumulation within the glomerulus, and pathogenetically by aberrant regulation of the alternative pathway of complement. Dense deposit disease is distinguished from other forms of C3 glomerulopathy by its characteristic appearance on electron microscopy. The extent to which dense deposit disease also differs from other forms of C3 glomerulopathy in terms of clinical features, natural history, and outcomes of treatment including renal transplantation is less clear. We discuss the pathophysiology of C3 glomerulopathy, with evidence for alternative pathway dysregulation obtained from affected individuals and complement factor H (Cfh)-deficient animal models. Recent linkage studies in familial C3 glomerulopathy have shown genomic rearrangements in the Cfh-related genes, for which the novel pathophysiologic concept of Cfh deregulation has been proposed.

Recent insights into C3 glomerulopathy

‘C3 glomerulopathy’ is a recent disease classification comprising several rare types of glomerulonephritis (GN), including dense deposit disease (DDD), C3 glomerulonephritis (C3GN) and CFHR5 nephropathy. These disorders share the key histological feature of isolated complement C3 deposits in the glomerulus. A common aetiology involving dysregulation of the alternative pathway (AP) of complement has been elucidated in the past decade, with genetic defects and/or autoantibodies able to be identified in a proportion of patients. We review the clinical and histological features of C3 glomerulopathy, relating these to underlying molecular mechanisms. The role of uncontrolled C3 activation in pathogenesis is emphasized, with important lessons from animal models. Methods, advantages and limitations of gene testing in the assessment of individuals or families with C3 glomerulopathy are discussed. While no therapy has yet been shown consistently effective, clinical evaluation of agents targeting specific components of the complement system is ongoing. However, limits to current knowledge regarding the natural history and the appropriate timing and duration of proposed therapies need to be addressed.

Spontaneous Resolution of Retinal Pigment Epithelial Detachments and Visual Improvement in Patient with MPGN II: A Case Report

A 31-year-old female suffering from membranoproliferative glomerulonephritis type II (MPGN II) presented to the Eye Casualty Department reporting a history of blurred and distorted vision. The patient appeared to have drusenoid retinal epithelial detachments and minimal intraretinal fluid. The subretinal deposits, basal lamina drusen, and pigment epithelial detachment appeared to resemble a “stars in the sky” picture with no symmetry between the eyes. The retinal pigment epithelial detachments improved and flattened over 18 month. and the best corrected visual acuity improved in the most affected eye. There was no evidence of neovascularization, and the intraretinal fluid disappeared spontaneously.

Animal models of age related macular degeneration

Age related macular degeneration (AMD) is the leading cause of vision loss of those over the age of 65 in the industrialized world. The prevalence and need to develop effective treatments for AMD has lead to the development of multiple animal models. AMD is a complex and heterogeneous disease that involves the interaction of both genetic and environmental factors with the unique anatomy of the human macula. Models in mice, rats, rabbits, pigs and non-human primates have recreated many of the histological features of AMD and provided much insight into the underlying pathological mechanisms of this disease. In spite of the large number of models developed, no one model yet recapitulates all of the features of human AMD. However, these models have helped reveal the roles of chronic oxidative damage, inflammation and immune dysregulation, and lipid metabolism in the development of AMD. Models for induced choroidal neovascularization have served as the backbone for testing new therapies. This article will review the diversity of animal models that exist for AMD as well as their strengths and limitations.

Complement involvement in neovascular ocular diseases

Pathological neovascularization (NV) is a hallmark of late stage neovascular age-related macular degeneration (AMD), diabetic retinopathy (DR), and retinopathy of prematurity (ROP). There is accumulating evidence that alterations in inflammatory and immune system pathways that arise from genetic differences, injury, and disease can predispose individuals to retinal neovascular eye diseases. Yet the mechanism of disease progression with respect to the complement system in these maladies is not fully understood. Recent studies have implicated the complement system as an emerging player in the etiology of several retinal diseases. We will summarize herein several of the complement system pathways known to be involved in ocular neovascular pathologies. Current treatment for many neovascular eye diseases focuses on suppression of NV with laser ablation, photodynamic therapy, or anti-VEGF angiogenic inhibitors. However, these treatments do not address the underlying cause of many of these diseases. A clear understanding of the cellular and molecular mechanisms could bring a major shift in our approach to disease treatment and prevention.

The eye in renal disease

This article summarizes the ocular pathology that can be seen in conjunction with renal disease. Both the eye and the kidney can be the target of systemic disease processes, but the eye can also be affected as a consequence of either renal disease or its treatment.

Vision-threatening retinal abnormalities in chronic kidney disease stages 3 to 5

BACKGROUND AND OBJECTIVES

Retinal abnormalities are common in inherited and acquired renal disease. This study determined the prevalence of retinal abnormalities in chronic kidney disease (CKD) stages 3 to 5.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

One hundred fifty patients with CKD stages 3 to 5 and 150 age- and gender-matched hospital patients with CKD stages 1 to 2 underwent bilateral retinal photography. These images were reviewed for incidental abnormalities, microvascular (Wong and Mitchell classification) and diabetic retinopathy (Airlie House criteria), and macular degeneration (Seddon classification).

RESULTS

Three (2%) patients with CKD stages 3 to 5 had retinal features characteristic of inherited renal disease (atrophy in Myopathy, Encephalopathy, Lactic Acidosis, Stroke-like episodes [MELAS] syndrome; and 2 with drusen in dense deposit disease). Fifty-nine (39%) patients had moderate-severe microvascular retinopathy (hemorrhages, exudates, etc.) compared with 19 (13%) with CKD stages 1 to 2. Forty-one (28%) had moderate-severe diabetic retinopathy (microaneurysms, exudates, etc.) compared with 16 (11%) with CKD stages 1 to 2. Ten (7%) had severe macular degeneration (geographic atrophy, hemorrhage, exudates, membranes) compared with one (1%) with CKD stages 1 to 2. Renal failure was an independent risk factor for microvascular retinopathy, diabetic retinopathy, and macular degeneration. Eleven (7.3%) patients with renal failure and one (0.7%) with CKD stages 1 to 2 had previously unrecognized vision-threatening retinal abnormalities that required immediate ophthalmologic attention.

CONCLUSIONS

Retinal abnormalities are common in CKD stages 3 to 5, and are more severe and more likely to threaten vision than in hospital patients with CKD stages 1 to 2.