Fundus changes in mesangiocapillary glomerulonephritis type II: clinical and fluorescein angiographic findings

Insights into human health from phenome- and genome-wide analyses of UK Biobank retinal optical coherence tomography phenotypes

The human retina is a complex multi-layered tissue which offers a unique window into systemic health and disease. Optical coherence tomography (OCT) is widely used in eye care and allows the non-invasive, rapid capture of retinal measurements in exquisite detail. We conducted genome- and phenome-wide analyses of retinal layer thicknesses using macular OCT images from 44,823 UK Biobank participants. We performed phenome-wide association analyses, associating retinal thicknesses with 1,866 incident ICD-based conditions (median 10-year follow-up) and 88 quantitative traits and blood biomarkers. We performed genome-wide association analyses, identifying inherited genetic markers which influence the retina, and replicated our associations among 6,313 individuals from the LIFE-Adult Study. And lastly, we performed comparative association of phenome- and genome- wide associations to identify putative causal links between systemic conditions, retinal layer thicknesses, and ocular disease. Independent associations with incident mortality were detected for photoreceptor thinning and ganglion cell complex thinning. Significant phenotypic associations were detected between retinal layer thinning and ocular, neuropsychiatric, cardiometabolic and pulmonary conditions. Genome-wide association of retinal layer thicknesses yielded 259 loci. Consistency between epidemiologic and genetic associations suggested putative causal links between thinning of the retinal nerve fiber layer with glaucoma, photoreceptor segment with AMD, as well as poor cardiometabolic and pulmonary function with PS thinning, among other findings. In conclusion, retinal layer thinning predicts risk of future ocular and systemic disease. Furthermore, systemic cardio-metabolic-pulmonary conditions promote retinal thinning. Retinal imaging biomarkers, integrated into electronic health records, may inform risk prediction and potential therapeutic strategies.

Physiology and pathology of the C3 amplification cycle: A retrospective

The C3 "Tickover" hypothesis, a mechanism whereby the host maintains constant surveillance of potential invading pathogens, targeting them for elimination through amplified C3b generation and C3-dependent effector mechanisms, was proposed by the late Professor Peter Lachmann in 1973. This unique insight came from a combined understanding of the complement system as it was then defined and the nature of the disease process in rare complement deficiencies and complement-driven diseases. In this review, I give a personal perspective of how understanding of "Tickover" has developed in the subsequent 50 years, culminating in the introduction into the clinic of therapeutic agents designed to combat amplification-driven disease.

Retinal obliterative vasculitis associated to contralateral retinal neovascularization in membranoproliferative glomerulonephritis

PURPOSE

To report our experience with a peculiar case of asynchronous bilateral retinal vascular occlusion in a patient suffering from membranoproliferative glomerulonephritis.

CASE REPORT

A 57-year-old dialysed male affected by membranoproliferative glomerulonephritis who underwent kidney transplantation complained of a sudden vision loss in his right eye (RE). His best-corrected visual acuity (BCVA) was 20/40 in RE and 20/20 in the left eye (LE); ophthalmological and fluorangiographic examinations revealed unilateral retinal obliterative vasculitis with panuveitis and apparent sparing of contralateral eye. About 6 months later the patient developed a branch retinal vein occlusion associated with a papillary neovascular membrane in LE. Corticosteroid therapy was administered and immunosuppressant dosage was increased with macular oedema reduction in both events.

CONCLUSION

We report a case of unilateral retinal obliterative vasculitis and subsequent contralateral retinal neovascularization and branch retinal vein occlusion in a patient affected by membranoproliferative glomerulonephritis.

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.

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.

Cloudy Cornea with Arcus Juvenilis in a Case of Dense Deposit Disease

A 25-year-old male patient presented with complaints of blurred vision in both eyes since 2 years. The patient was a known case of nephrotic syndrome with dyslipidaemia for which he was on diuretics and lipid-lowering agents for 3 years. On examination, his visual acuity was 6/9 in both eyes with cloudy cornea and arcus juvenilis. Fundus examination was within normal limits. On systemic work-up, his lipid profile was deranged with increased serum total cholesterol, very low density lipoprotein, low density lipoprotein and triglyceride. The serum high density lipoprotein was decreased. Renal function test revealed elevated serum creatinine with significant proteinuria. Renal biopsy was suggestive of dense deposit disease on immunofluorescence and transmission electron microscopy. Ocular manifestation of dense deposit disease is characterised by retinal drusen, pigmentary atrophy, choroidal neovascular membrane and atypical serous retinopathy. To the best of our knowledge, anterior segment changes in dense deposit disease has not been reported. This is the first case reporting cloudy cornea with arcus juvenilis in a case of dense deposit disease.

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.

Bilateral Diffuse and Cluster Pigment Epithelial Detachment Associated with Diffuse Proliferative Glomerulonephritis

Retinal pigment epithelium detachment (PED) is an area of retinal pigment epithelium (RPE) elevation with minimal or no sensory retinal detachment resulting from the accumulation of sub-RPE fluid. There are many etiological factors that lead to the development of PED. PED may be observed as an isolated finding or in association with ocular and systemic conditions. In this case we report a 23-year-old male with bilateral cluster PED associated with diffuse proliferative glomerulonephritis (DPGN). The importance of current report is that development of PED and DPGN is more than a simple incidental event. Patients with DPGN should have regular fundus examinations, and follow-up should be conducted by an ophthalmologist who is aware of the possible presence of these diseases.

Multimodal imaging of retinal pigment epithelial detachments in patients with C3 glomerulopathy: case report and review of the literature

Background

To describe the optical coherence tomography angiograhy (OCTA) of drusenoid pigment epithelial detachments (PEDs) in a woman affected by Complement 3 (C3) glomerulopathy, which represents a spectrum of glomerular diseases characterized on fluorescent microscopy by C3 accumulation with absent, or scanty, immunoglobulin deposits. It is due to acquired or genetically defective alternative pathway control and is generally associated with drusen-like deposits in Bruch’s membrane, as well as choriocapillaris. These retinal lesions can be associated with choroidal neovascularization and central serous chorioretinopathy (CSCR). OCTA is useful to detect neovascularization without injecting a contrast product, particularly in these patients who may have renal insufficiency.

Case presentation

A 28-year-old woman affected by C3 glomerulpathy was diagnosed with asymptomatic multiple bilateral PEDs during a routine ophthalmologic consultation. To better characterize the lesions, multimodal imaging was performed and included: optic coherence tomography (OCT), en-face OCT, OCTA, fluorescence and indocyanine angiography. The OCTA clearly identified vascular network rarefaction with decreased choriocapillary vascularization. It confirmed that PEDs associated with C3 glomerulonephritis are not vascularized, but rather of serous type.

Conclusions

Patients affected by C3 glomerulopathy can develop neovascular membranes as retinal complications of pigment epithelial detachments. Optical coherence angiography may be indicated to identify this complication, without injecting any contrast product that could produce further kidney damage.

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.

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.

Retinal disease in the C3 glomerulopathies and the risk of impaired vision

BACKGROUND

Dense deposit disease and atypical hemolytic uremic syndrome are often caused by Complement Factor H (CFH) mutations. This study describes the retinal abnormalities in dense deposit disease and, for the first time, atypical haemolytic uremic syndrome. It also reviews our understanding of drusen pathogenesis and their relevance for glomerular disease.

METHODS

Six individuals with dense deposit disease and one with atypical haemolytic uremic syndrome were studied from 2 to 40 years after presentation. Five had renal transplants. All four who had genetic testing had CFH mutations. Individuals underwent ophthalmological review and retinal photography, and in some cases, optical coherence tomography, and further tests of retinal function.

RESULTS

All subjects with dense deposit disease had impaired night vision and retinal drusen or whitish-yellow deposits. Retinal atrophy, pigmentation, and hemorrhage were common. In late disease, peripheral vision was restricted, central vision was distorted, and there were scotoma from sub-retinal choroidal neovascular membranes and atypical serous retinopathy. Drusen were present but less prominent in the young person with atypical uremic syndrome due to a heterozygous CFH mutation.

CONCLUSIONS

Drusen are common in forms of C3 glomerulopathy caused by compound heterozygous or heterozygous CFH mutations. They are useful diagnostically but also impair vision. Drusen have an identical composition to glomerular deposits. They are also identical to the drusen of age-related macular degeneration, and may respond to the same treatments. Individuals with a C3 glomerulopathy should be assessed ophthalmologically at diagnosis, and monitored regularly for vision-threatening complications.

Age-related macular degeneration: genome-wide association studies to translation

In recent years, genome-wide association studies (GWAS), which are able to analyze the contribution to disease of genetic variations that are common within a population, have attracted considerable investment. Despite identifying genetic variants for many conditions, they have been criticized for yielding data with minimal clinical utility. However, in this regard, age-related macular degeneration (AMD), the most common form of blindness in the Western world, is a striking exception. Through GWAS, common genetic variants at a number of loci have been discovered. Two loci in particular, including genes of the complement cascade on chromosome 1 and the ARMS2/HTRA1 genes on chromosome 10, have been shown to convey significantly increased susceptibility to developing AMD. Today, although it is possible to screen individuals for a genetic predisposition to the disease, effective interventional strategies for those at risk of developing AMD are scarce. Ongoing research in this area is nonetheless promising. After providing brief overviews of AMD and common disease genetics, we outline the main recent advances in the understanding of AMD, particularly those made through GWAS. Finally, the true merit of these findings and their current and potential translational value is examined.Genet Med 18 4, 283-289.

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.

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.

Age-related macular degeneration: genetic and clinical findings

Age-related macular degeneration (AMD) is a sight threatening eye disease that affects millions of humans over the age of 65 years. It is considered to be the major cause of irreversible blindness in the elderly population in the developed world. The disease is prevalent in Europe and the United States, which has a large number of individuals of European descent. AMD is characterized by a progressive loss of central vision attributable to degenerative and neovascular changes that occur in the interface between the neural retina and the underlying choroid. This location contains the retinal photoreceptors, the retinal pigmented epithelium, a basement membrane complex known as Bruch's membrane and a network of choroidal capillaries. AMD is increasingly recognized as a complex genetic disorder where one or more genes contribute to an individual's susceptibility to development of the condition, while the prevailing view is that the disease stems from the interaction of multiple genetic and environmental factors. Although it has been proposed that a threshold event occurs during normal aging, the sequelae of biochemical, cellular, and molecular events leading to AMD are not fully understood. Here, we review the clinical aspects of AMD and summarize the genes which have been reported to have a positive association with the disease.

The significance of the complement system for the pathogenesis of age-related macular degeneration - current evidence and translation into clinical application

BACKGROUND

Dysregulation of the complement system has been shown to play a major role in the pathogenesis of age-related macular degeneration (AMD).

METHODS

The current evidence from human studies derives from immunohistochemical and proteomic studies in donor eyes, genetic association studies, and studies of blood complement protein levels. These lines of evidence are corroborated by in vitro and animal studies.

RESULTS

In AMD donor eyes, detection of complement proteins in drusen suggested local inflammatory processes involving the complement system. Moreover, higher levels of complement proteins in the Bruch's membrane/choroid complex could be detected in AMD donor eyes compared to controls. A large number of independent genetic studies have consistently confirmed the association of AMD with risk or protective variants in genes coding for complement proteins, including complement factor H (CFH), CFH-related proteins 1 and 3, factor B/C2, C3 and factor I. Another set of independent studies detected increased levels of complement activation products in plasma of AMD patients, suggesting that AMD may be a systemic disease and the macula a vulnerable anatomic site of minimal resistance to complement activation. Genotype-phenotype correlations, including the impact of genetic variants on disease progression, gene-environment and pharmacogenetic interactions, have been investigated. There is evidence that complement gene variants may be associated with the progression from early to late forms of AMD, whereas they do not appear to play a significant role when late atrophic AMD has already developed. There are indications for an interaction between genetic variants and supplementation and dietary factors. Also, there is some evidence that variants in the CFH gene influence treatment effects in patients with neovascular AMD.

CONCLUSIONS

Such data suggest that the complement system may have a significant role for developing new prophylactic and therapeutic interventions in AMD. In fact, several compounds acting on the complement pathway are currently in clinical trials. Therapeutics that modulate the complement system need to balance inhibition with preservation of sufficient functional activity in order to maintain adequate immune responses and tissue homeostasis. Specifically, targeting the dysfunction appears more adequate than a global suppression of complement activation in chronic diseases such as AMD.

The amplification loop of the complement pathways

The C3 amplification loop lies at the core of all the complement pathways, rather than the alternative pathway alone. It is, in evolutionary terms, the oldest part of the complement system and its antecedents can be seen in insects and in echinoderms. The amplification loop is the balance between two competing cycles both acting on C3b: the C3 feedback cycle which enhances amplification and the C3 breakdown cycle which downregulates it. It is solely the balance between their rates of reaction on which amplification depends. The C3 breakdown cycle generates iC3b as its primary reaction product. iC3b, through its reaction with the leukocyte integrins (and complement receptors) CR3 (CD11b/CD18) and CR4 (CD11c/CD18), is the most important mechanism by which complement mediates inflammation. A variety of genetic polymorphisms in components of the amplification loop have been shown to predispose to two kidney diseases-dense deposit disease and atypical haemolytic uraemic syndrome-and to age-related macular degeneration. All predisposing alleles enhance amplification, whereas protective alleles downregulate amplification. This leads to the conclusion that there is a "hyperinflammatory complement phenotype" determined by these polymorphisms. This hyperinflammatory phenotype protects against bacterial infections in early life but in later life is associated with immunopathology. Besides the diseases already mentioned, there is evidence that this hyperinflammatory complement phenotype may predispose to accelerated atherosclerosis and also shows an association with Alzheimer's disease. Downregulation of the amplification loop therefore constitutes an important therapeutic target.

Localization of complement 1 inhibitor (C1INH/SERPING1) in human eyes with age-related macular degeneration

Age-related macular degeneration (AMD) is a common degenerative disease resulting in injury to the retina, retinal pigment epithelium and choriocapillaris. Recent data from histopathology, animal models and genetic studies have implicated altered regulation of the complement system as a major factor in the incidence and progression of this disease. A variant in the gene SERPING1, which encodes C1INH, an inhibitor of the classical and lectin pathways of complement activation, was recently shown to be associated with AMD. In this study we sought to determine the localization of C1INH in human donor eyes. Immunofluorescence studies using a monoclonal antibody directed against C1INH revealed localization to photoreceptor cells, inner nuclear layer neurons, choriocapillaris, and choroidal extracellular matrix. Drusen did not exhibit labeling. Genotype at rs2511989 did not appear to affect C1INH abundance or localization, nor was it associated with significant molecular weight differences when evaluated by Western blot. In a small number of eyes (n = 7 AMD and n = 7 control) AMD affection status was correlated with increased abundance of choroidal C1INH. These results indicate that C1INH protein is present in the retina and choroid, where it may regulate complement activation.

Complement factor H polymorphisms, renal phenotypes and age-related macular degeneration: the Blue Mountains Eye Study

Complement factor H (CFH) is a key regulator of the alternative pathway of complement and its mutations have been associated with membranoproliferative glomerulonephritis type II, atypical hemolytic uremic syndrome and age-related macular degeneration (AMD), suggesting that alternative pathway dysregulation is a common pathogenetic feature of these ocular and renal conditions. In this study we tested the hypothesis that common CFH variants have a global role in renal function in the Australian population-based Blue Mountains Eye Study (BMES). We replicated the association of I62V with estimated glomerular filtration rate (GFR; P=0.017) and creatinine clearance (CRCL; P=0.015). The minor allele of I62V (G) was deleterious: adding one copy of the G allele decreased GFR/CRCL by approximately 0.98 ml min(-1) per 1.73 m(2) (95% confidence interval (CI): 0.97, 0.99). We also replicated the association of Y402H with AMD and provided an unbiased estimate of population attributable risk (PAR). The minor allele of Y402H (C) was deleterious: the odds ratio estimate of CC genotype compared to TT was 1.87 (95% CI: 1.44, 2.45). The PAR of the C allele was estimated as 0.22 (95% CI: 0.15, 0.28). In summary, in the BMES population we confirmed the association between I62V and renal function, as measured by the estimated GFR, plus the association of Y402H with both early- and late-stage AMD.

Progress in defining the molecular biology of age related macular degeneration

Age related macular degeneration (AMD) is an extremely prevalent complex genetic disorder. Its incidence rises exponentially in the elderly to a frequency of 1 in 2 in the general population by age 85. It affects approximately 25 million people and is the commonest cause of irreversible visual loss in the Western world. It is therefore a major public health problem. However, until recently its aetiology was unknown. Our understanding of both the molecular biology of AMD and the relevant clinical treatments has progressed dramatically in the last 2 years. Two genes of large effect have been identified which together contribute to over 70% of the population attributable risk of AMD. Treatments which inhibit expression of vascular endothelial growth factor have been developed which can rescue vision in the "wet" form of the disease. The association of complement factor H with AMD highlights the importance of the alternative complement pathway in the development of AMD whilst the pathophysiology of the serine protease HTRA1 is now under intensive study. This review will give an insight into these developments and will summarise our current knowledge of the molecular biology of AMD.

Macular degeneration: recent advances and therapeutic opportunities

The central retina mediates high acuity vision, and its progressive dysfunction due to macular degeneration is the leading cause of visual disability among adults in industrialized societies. Here, we summarize recent progress in understanding the pathophysiology of macular degeneration and the implications of this new knowledge for treatment and prevention. The past decade has witnessed remarkable advances in this field, including the development of new, non-invasive retinal imaging technologies, the development of animal models for macular disease, and the isolation of many of the genes responsible for both early- and late-onset macular diseases. These advances have set the stage for the development of effective mechanism-based therapies.

Microperimetric evaluation of macula in retinopathy of membranoproliferative glomerulonephritis type II: a case report

PURPOSE

To report on the microperimetric evaluation of the central visual field in a patient with retinopathy due to membranoproliferative glomerulonephritis.

METHODS

The central 20 degrees visual field was evaluated using fundus-related perimetry with (Nidek MP1) microperimeter in a patient with proven membranoproliferative glomerulonephritis type II, who had multiple drusen-like lesions involving the posterior pole of both eyes, with corresponding window defects on fundus fluorescein angiogram.

RESULTS

Static threshold perimetry of the central 20 degrees using a 10 dB threshold, Goldmann size II stimulus, with (Nidek-MP1) microperimeter showed reduction in retinal sensitivity in the parafoveal and in the temporal paramacular areas in both the eyes that had drusen-like lesions.

CONCLUSIONS

Early loss of function in retinopathy of membranoproliferative glomerulonephritis type II can probably be detected by fundus-related microperimetry.

Retinal changes associated with type 2 glomerulonephritis

AIMS

The aims of this study were to: Investigate retinal changes associated with type 2 membranoproliferative glomerulonephritis (type 2 MPGN). Assess whether there was a relationship between the severity of the kidney disease and ophthalmoscopically visible fundal changes. Find out if renal transplantation was linked with visual deterioration. Decide if patients with type 2 MPGN need to be referred for ophthalmological assessment.

METHODS

The patients were identified from pathology department records as having renal biopsy proven type 2 MPGN from January 1981 to October 2003. Patients were invited to attend for ophthalmic assessment.

RESULTS

A total of 26 biopsy proven cases of type 2 MPGN were identified. One patient lost vision from a possible occult choroidal neovascular membrane. The extent of ocular involvement did not consistently appear to be related to the severity of the renal involvement, although there was a relationship between the presence of ocular lesions and the duration of the disease. The longer the disease was present the more likely the patients were to have ophthalmoscopically visible fundal changes. Renal transplantation did not appear to have a detrimental effect on vision with the possible exception of one patient.

CONCLUSION

Referral of type 2 MPGN patients by the renal physician for an initial ophthalmological assessment may be beneficial so that symptoms of choroidal neovascularization can be explained and patients advised to seek urgent help if distortion of central vision occurs. Renal transplantation does not appear to be a risk factor for the development of choroidal neovascular membranes.

INDOCYANINE GREEN ANGIOGRAPHIC FINDINGS FOR PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS NEPHROPATHY

PURPOSE

To study indocyanine green (ICG) angiographic findings for patients with systemic lupus erythematosus (SLE) nephropathy. In particular, the presence of choroidal abnormalities at ICG angiography, which could not be detected by fluorescein angiography, was studied.

DESIGN

Observational case report study.

METHODS

Nine consecutive female patients (mean age +/- SD, 38.2 +/- 9.7 years) with SLE-related nephropathy underwent simultaneous ICG angiography and fluorescein angiography according to a standard angiographic protocol for uveitis.

RESULTS

Two findings were revealed by ICG angiography: focal, transient hypofluorescent areas in the early phase; and spots of choroidal hyperfluorescence visible from the intermediate to late phase.

CONCLUSIONS

ICG angiography can provide information that is not detectable by clinical or fluorescein angiographic examination for patients with lupus nephropathy. This information may prove useful in better understanding the pathogenesis of SLE choroidopathy.

Variations in the complement regulatory genes factor H (CFH) and factor H related 5 (CFHR5) are associated with membranoproliferative glomerulonephritis type II (dense deposit disease)

INTRODUCTION

Membranoproliferative glomerulonephritis type II or dense deposit disease (MPGN II/DDD) causes chronic renal dysfunction that progresses to end stage renal disease in about half of patients within 10 years of diagnosis. Deficiency of and mutations in the complement factor H (CFH) gene are associated with the development of MPGN II/DDD, suggesting that dysregulation of the alternative pathway of the complement cascade is important in disease pathophysiology.

SUBJECTS

Patients with MPGN II/DDD were studied to determine whether specific allele variants of CFH and CFHR5 segregate preferentially with the MPGN II/DDD disease phenotype. The control group was compromised of 131 people in whom age related macular degeneration had been excluded.

RESULTS

Allele frequencies of four single nucleotide polymorphisms in CFH and three in CFHR5 were significantly different between MPGN II/DDD patients and controls.

CONCLUSION

We have identified specific allele variants of CFH and CFHR5 associated with the MPGN II/DDD disease phenotype. While our data can be interpreted to further implicate complement in the pathogenesis of MPGN II/DDD, these associations could also be unrelated to disease pathophysiology. Functional studies are required to resolve this question.

Membranoproliferative glomerulonephritis type II (dense deposit disease): an update

Membranoproliferative glomerulonephritis type II (MPGN II) is a rare disease characterized by the deposition of abnormal electron-dense material within the glomerular basement membrane of the kidney and often within Bruch's membrane in the eye. The diagnosis is made in most patients between the ages of 5 and 15 yr, and within 10 yr, approximately half progress to end-stage renal disease, occasionally with the late comorbidity of visual impairment. The pathophysiologic basis of MPGN II is associated with the uncontrolled systemic activation of the alternative pathway (AP) of the complement cascade. In most patients, loss of complement regulation is caused by C3 nephritic factor, an autoantibody directed against the C3 convertase of the AP, but in some patients, mutations in the factor H gene have been identified. For the latter patients, plasma replacement therapy prevents renal failure, but for the majority of patients, there is no proven effective treatment. The disease recurs in virtually all renal allografts, and a high percentage of these ultimately fail. The development of molecular diagnostic tools and new therapies directed at controlling the AP of the complement cascade either locally in the kidney or at the systemic level may lead to effective treatments for MPGN II.

Visual impairment caused by retinal abnormalities in mesangiocapillary (membranoproliferative) glomerulonephritis type II ("dense deposit disease")

Patients with mesangiocapillary glomerulonephritis (MCGN) type II usually present by early adulthood with hematuria, proteinuria, and renal impairment, and these features often are accompanied by a partial lipodystrophy and an autoantibody for the alternative complement pathway convertase (C3NeF). The diagnosis of MCGN type II depends on the demonstration of "dense deposits" in the glomerular basement membrane (GBM). Most patients also have multiple subretinal white spots or drusen that are histopathologically identical with the GBM deposits and evident ophthalmoscopically by the time renal failure develops. Initially visual acuity and visual fields are preserved, but fluorescein angiography and specialized tests of retinal function, such as dark adaptation, electroretinography, and electrooculography, may be abnormal and will worsen progressively. Over the next 20 years, vision often deteriorates because of retinal atrophy, and sometimes because of subretinal neovascular membranes, macular detachment, and central serous retinopathy. The authors describe a patient with MCGN type II who presented with renal failure and impaired vision at the age of 59. He already had widespread retinal atrophy, and subsequently a subretinal membrane developed. The drusen seen in MCGN type II, like the partial lipodystrophy, are a helpful clinical pointer to the diagnosis of this condition. All patients with MCGN type II should be warned of the risk of retinal complications and reviewed by an ophthalmologist at presentation and regularly after about 10 years to minimize the loss of visual acuity from complications of the retinopathy.

Structure and composition of drusen associated with glomerulonephritis: implications for the role of complement activation in drusen biogenesis

PURPOSE

The ocular fundi of many patients with membranoproliferative glomerulonephritis type II (MPGN-II) are characterised by the presence of deposits within Bruch's membrane that resemble drusen, hallmark lesions associated with age-related macular degeneration (AMD). Glomerulonephritis (GN)-associated drusen appear at a younger age, however, than do drusen in individuals with AMD. In light of recent evidence that immune-mediated events participate in drusen biogenesis and AMD, we examined the structure and composition of drusen in eyes obtained from human donors with two distinct glomerulopathies, both of which involve complement deposition within glomeruli. These features were compared with those of drusen from patients with clinically documented AMD.

METHODS

Eyes obtained from two human human donors diagnosed with membranous and post-streptococcal GN, respectively, were analysed histochemically, immunohistochemically and ultrastructurally.

RESULTS

Subretinal pigment epithelial (RPE) deposits in both types of GN are numerous and indistinguishable, both structurally and compositionally, from drusen in donors with AMD. GN-associated drusen exhibit sudanophilia, bind filipin, and react with antibodies directed against vitronectin, complement C5 and C5b-9 complexes, TIMP-3 and amyloid P component. Drusen from the membranous GN donor, but not the post-streptococcal GN donor, reacted with peanut agglutinin and antibodies directed against MHC class II antigens and IgG. The ultrastructural characteristics of these deposits were also identical with those of AMD-associated drusen.

CONCLUSIONS

The composition and structure of ocular drusen associated with membranous and post-streptococcal/segmental GN are generally similar to those of drusen in individuals with AMD. In view of the recent data supporting the involvement of complement activation in drusen biogenesis and the pathobiology of AMD, further studies of the biological relationships between AMD and diseases associated with complement activation are warranted.

Retinal function abnormalities in membranoproliferative glomerulonephritis type II

PURPOSE

To characterize retinal electrophysiologic and psychophysical abnormalities associated with membranoproliferative glomerulonephritis type II.

METHODS

Three adults with membranoproliferative glomerulonephritis type II were studied. Retinal function was measured psychophysically (automated perimetry, Farnsworth D-15 color vision testing, and dark adaptometry) and electrophysiologically (full-field flash electroretinography and electro-oculography).

RESULTS

Two symptomatic individuals had prominent drusenlike deposits and retinal pigment epithelial disturbances, findings characteristic of membranoproliferative glomerulonephritis type II retinopathy. These individuals had mild visual field and color vision abnormalities, prolonged dark adaptation, and delayed electroretinographic dark-adapted dim and bright flash responses of normal amplitude. The electro-oculogram of the most severely affected individual was abnormal. The third individual who was asymptomatic had the mildest fundus abnormalities and exhibited normal psychophysical and electrophysiologic responses.

CONCLUSIONS

Membranoproliferative glomerulonephritis type II retinopathy may be associated with symptomatic and measurable psychophysical and electrophysiologic abnormalities of retinal function.

Electrophysiology of type II mesangiocapillary glomerulonephritis with associated fundus abnormalities

The retinal electrophysiology is reported in four patients with type II mesangiocapillary glomerulonephritis and partial lipodystrophy with associated fundus abnormalities and no visual symptoms. The histological hallmark of the condition is that of widespread electron dense deposits in the renal glomerulus and in the choriocapillaris and Bruch's membrane of the eye. Three of the four patients had the typical fundal appearance of multiple, yellow, drusen-like lesions at the posterior pole of the eye with normal visual acuity. These three patients had abnormally low Arden ratios on electro-oculography with normal electroretinography responses. This is the first clinical model of disease known to be isolated to the choriocapillaris and Bruch's membrane causing an electro-oculographic abnormality without any clinically detectable deficit in visual function.

Membranoproliferative glomerulonephritis type II associated with central serous retinopathy

Membranoproliferative glomerulonephritis type II is specifically associated with the presence of dense deposits in the basement membrane of Bruch's membrane, which result in lesions similar to basal laminar drusen, exudative drusen, and retinal pigment epithelial detachments. In advanced stages of this dense-deposit retinopathy, choroidal neovascularization may occur. We observed a 36-year-old patient with membranoproliferative glomerulonephritis type II who developed central serous retinopathy in the presence of specific dense-deposit-associated fundus lesions. The diffuse drusenlike dense deposits (at the level of Bruch's membrane) and associated retinal pigment epithelial detachments appear to contribute to the pathogenesis of central serous retinopathy. Thus changes in Bruch's membrane may be involved in the development of central serous retinopathy.

Posterior segment changes in membranoproliferative glomerulonephritis

Membranoproliferative glomerulonephritis is a renal disorder characterized by proliferation of cells and changes in the basement membrane of the glomerulus. The disease is divided into three subtypes: type I, characterized by the presence of subendothelial electrondense deposits; type II, characterized by deposition of electrondense material of unknown origin in the lamina densa of the glomerular basement membrane; and type III, characterized by lesions having both type I and type II qualities. Specific posterior segment changes have been reported with membranoproliferative glomerulonephritis type II. We examined three patients with membranoproliferative glomerulonephritis type II and two patients with type III disease. All three patients with type II disease had Bruch's membrane and retinal pigment epithelial changes, whereas both patients with type III disease had normal posterior segments.

Idiopathic membranoproliferative glomerulonephritis in childhood

Membranoproliferative glomerulonephritis (MPGN), recognized since 1965, is now known to have three forms, designated types I, II, and III. The types are similar in the frequency of hypocomplementemia and clinical course but are dissimilar in glomerular ultrastructure, pathogenesis, mechanisms of complement activation, predisposition to recur in the renal transplant, and, to some extent, in clinical presentation. Although glomerular proliferation is usually diffuse, it may be focal and segmental particularly in mild cases of MPGN I. Hypocomplementemia, present in about 80% of patients, is the result of hypercatabolism of C3 by three mechanisms as well as of diminished C3 synthesis. The hypocomplementemia is unrelated to clinical course or prognosis. Although MPGN I and III both have a high frequency of an extended haplotype on chromosome 6, which has known associations with autoimmune phenomena, and both have a high frequency of inherited complement defects, they are nevertheless dissimilar in glomerular ultrastructure, complement profile, and immunohistology in ways which suggest a wide difference in pathogenesis. Abnormalities in humoral immunity appear not to be involved in MPGN III. Treatment with anticoagulant, antiplatelet and cytotoxic drugs have, in controlled trials, been either ineffective or marginally effective. Long-term use of alternate-day prednisone in high dosage appears to be the most efficacious regimen in both controlled and uncontrolled studies.

Fundus changes in membranoproliferative glomerulonephritis type II. A fluorescein angiographic study of 23 patients

A total of 23 patients aged between 11 and 64 years who had biopsy-proven membranoproliferative glomerulonephritis type II (dense deposit disease) were studied using fluorescein angiography of the retina. With the exception of two adolescents, all patients exhibited small subretinal nodules that were similar to basal laminar drusen. Subjects with a long history of renal disease displayed more numerous and larger nodules as well as atrophic changes. Four subjects presented with subretinal neovascular membranes.

Specific eye fundus lesions in type II membranoproliferative glomerulonephritis

In three adolescents, suffering from membrano-proliferative glomerulonephritis type II, ophthalmoscopy and fluorescein angiography revealed retinal pigment epithelium lesions, referred to as basal laminar drusen. The patient with the longest renal history had the most pronounced fundus changes. These lesions, earlier described in adult patients, are believed to be specific for this particular form of chronic glomerulonephritis.

Subretinal neovascular membranes associated with chronic membranoproliferative glomerulonephritis type II

Subretinal neovascular membranes were observed in three patients with chronic membranoproliferative glomerulonephritis type II (dense deposit disease). The first signs of glomerulonephritis occurred at respective ages of 13, 10 and 10 years; subretinal neovascular membranes were noted at respective ages of 25, 32 and 32 years. All patients had bilateral, widespread retinal pigment epithelial abnormalities. Our findings indicate that subretinal neovascularization is a complication of dense deposit disease. In one patient, the early recognition and laser treatment of an extrafoveal subretinal neovascular membrane prevented further loss of vision.

Fundus changes in chronic membranoproliferative glomerulonephritis type II

Chronic membranoproliferative glomerulonephritis type II (dense deposit disease) is a renal disease characterized by dense deposits in the glomerular and tubular basement membranes. We report a retinopathy with diffuse retinal pigment alterations in 11 out of 12 patients with this disease. Four of the eleven patients also presented disciform macular detachment and choroidal neovascularisation. The lesions were observed at the earliest 1 year after the diagnosis of the renal disease. In a control group of 17 patients with chronic membranoproliferative glomerulonephritis type I none of the patients presented similar fundus lesions.

Alport syndrome, basement membranes and collagen

Alport syndrome, an inherited disorder of the kidney, eye and ear, has fascinated nephrologists, pathologists, and geneticists for nearly a century. With the recent application of molecular biochemical and genetic techniques, this mysterious disease has begun to yield some of its secrets. Alport syndrome can now be viewed as a generalized disorder of basement membranes that appears to result from mutations in an X-chromosome-encoded basement membrane collagen chain. This chain, along with two other novel collagen chains, is absent from Alport basement membranes, in contrast to the classical chains of collagen IV. Phenotypic heterogeneity in Alport syndrome probably arises from allelic mutations at a single genetic locus. The phenomenon of post-transplant anti-glomerular basement membrane nephritis may be a manifestation of specific mutations at the Alport locus that prevent synthesis of the gene's protein product and the establishment of immunological tolerance.