Case report of atypical hemolytic uremic syndrome with retinal arterial and venous occlusion treated with eculizumab

Atypical Hemolytic-Uremic Syndrome: Genetic Basis, Clinical Manifestations, and a Multidisciplinary Approach to Management

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy (TMA) defined by the triad of hemolytic anemia, thrombocytopenia, and acute kidney injury. Microthrombi develop in the glomerular capillaries secondary to endothelial damage and exert shear stress on red blood cells, consume platelets, and contribute to renal dysfunction and failure. Per current understanding of pathophysiology, HUS is classified into infectious, secondary, and atypical disease. The most common etiology is infectious sequelae of Shiga toxin-producing Escherichia coli (STEC); other causative organisms include shigella and salmonella. Secondary HUS arises from cancer, chemotherapy, solid organ and hematopoietic stem cell transplant, pregnancy, or autoimmune disorders. Primary atypical hemolytic-uremic syndrome (aHUS) is associated with genetic mutations in complement and complement regulatory proteins. Under physiologic conditions, complement regulators keep the alternative complement system continuously active at low levels. In times of inflammation, mutations in complement-related proteins lead to uncontrolled complement activity. The hyperactive inflammatory state leads to glomerular endothelial damage, activation of the coagulation cascade, and TMA findings. Atypical hemolytic-uremic syndrome is a rare disorder with a prevalence of 2.21 to 9.4 per million people aged 20 years or younger; children between the ages of 0 and 4 are most affected. Multidisciplinary health care is necessary for timely management of its extra-renal manifestations. These include vascular disease of the heart, brain, and skin, pulmonary hypertension and hemorrhage, and pregnancy complications. Adequate screening is required to monitor for sequelae. First-line treatment is the monoclonal antibody eculizumab, but several organ systems may require specialized interventions and coordination of care with sub-specialists.

[Retinal tomography features of thrombotic microangiopathy associated with atypical hemolytic-uremic syndrome]

OBJECTIVE

To evaluate structural and morphological changes in the retina using optical coherence tomography (OCT) in patients with thrombotic microangiopathy (TMA) associated with atypical hemolytic-uremic syndrome (aHUS).

MATERIAL AND METHODS

The study analyzed OCT data of 14 patients (28 eyes) with an established diagnosis of aHUS including such indicators as central retinal thickness (CRT), thickness of the retinal nerve fiver layer (RNFL), ganglion cell layer (GCL), retinal pigment epithelium (RPE), etc.

RESULTS

Patients with aHUS were noted to have an increase in CRT, paracentral acute middle maculopathy in the form of a hyperreflective defect primarily of the inner nuclear layer of paracentral localization, as well as disorganization of the RPE, which was observed statistically significantly more often compared to healthy persons (p=0.0001, p=0.001 and p=0.009 respectively). In the subgroup with thrombotic retinopathy (6 people) a statistically significant increase in CRT and peripapillary RNFL was found (p=0.004 and p=0.001) compared to patients without thrombotic retinopathy, as well as the presence of paracentral acute middle maculopathy and transudative macular retinoschisis (p=0.0001 and p=0.004). A statistically significant thinning of the peripapillary RNFL was revealed (p=0.0001) in the subgroup with symptoms of Purtscher-like retinopathy (PLR) found retrospectively (4 people) compared to patients without retrospective PLR symptoms. A statistically significant decrease in CRT was revealed (p=0.018) in the subgroup of patients receiving systemic therapy with eculizumab (5 people) compared with patients not receiving this therapy. Statistically significant correlations were recorded between the studied OCT indicators, laboratory indicators, and the level of systolic blood pressure (p<0.05).

CONCLUSION

According to OCT, paracentral acute middle maculopathy is a biomarker of thrombotic retinopathy and the activity of systemic TMA associated with aHUS. Arterial hypertension is an additional aggravating factor in the development of paracentral acute middle maculopathy and transudative macular retinoschisis. Targeted therapy with eculizumab leads to an effective decrease in CRT, which is potentially associated with regression of ischemic edema. The outcome of PLR involves thinning of peripapillary RNFL.

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.

[Ocular manifestations of primary thrombotic microangiopathy]

The article reviews literature on ocular manifestations of primary thrombotic microangiopathy. Thrombotic microangiopathy is a clinical and morphological syndrome that characterizes a systemic disseminated lesion of the microcirculatory bed, it is a special type of vascular damage that combines thrombosis and inflammation of the vascular wall leading to occlusion of the vessel lumen, causing ischemic damage to various organs and tissues. The classic types of primary thrombotic microangiopathy are thrombotic thrombocytopenic purpura, shigatoxin-associated hemolytic uremic syndrome (STEC-HUS) and atypical hemolytic uremic syndrome. Thrombotic thrombocytopenic purpura and atypical hemolytic uremic syndrome are characterized by ischemic damage to the visual organ as a result of suspected thrombotic microangiopathy in the microcirculatory bed of the eye. The clinical picture of ocular manifestations of these diseases is similar, however the damage to the eye in the form of ischemic Purtscher-like retinopathy is more characteristic of atypical hemolytic uremic syndrome, which may be due to chronic uncontrolled activation of the alternative complement pathway in this disorder. Timely initiation of systemic therapy of the underlying disease in most cases leads to complete restoration of visual functions. A thorough ophthalmological examination of patients with these diseases is required.

Peripheral Ulcerative Keratitis Secondary to Atypical Hemolytic Uremic Syndrome

PURPOSE

To report a case of peripheral ulcerative keratitis secondary to atypical hemolytic uremic syndrome.

METHODS

We report the case of a 76-year-old man who presented with bilateral aggressive peripheral ulcerative keratitis. Clinical examinations and investigations are reported from the patients' admission.

RESULTS

The patient had an extended workup for autoimmune and infectious etiologies that all returned negative. The laboratory work in conjunction with renal biopsy and clinical symptoms were consistent with atypical hemolytic uremic syndrome. The patient was treated with systemic steroids for his peripheral ulcerative keratitis and underlying systemic disease. Corneal glueing and amniotic membrane grafting was also performed.

CONCLUSIONS

To our knowledge, we report the first known case of peripheral ulcerative keratitis secondary to atypical hemolytic uremic syndrome. In cases where the standard workup is negative, this diagnosis should be considered because it can have significant systemic morbidity.

Multidisciplinary Approach to the Diagnosis and In-Hospital Management of COVID-19 Infection: A Narrative Review

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2 or COVID-19 disease) was declared a pandemic on 11th March 2020 by the World Health Organization. This unprecedented circumstance has challenged hospitals' response capacity, requiring significant structural and organizational changes to cope with the surge in healthcare demand and to minimize in-hospital risk of transmission. As our knowledge advances, we now understand that COVID-19 is a multi-systemic disease rather than a mere respiratory tract infection, therefore requiring holistic care and expertise from various medical specialties. In fact, the clinical spectrum of presentation ranges from respiratory complaints to gastrointestinal, cardiac or neurological symptoms. In addition, COVID-19 pandemic has created a global burden of mental illness that affects the general population as well as healthcare practitioners. The aim of this manuscript is to provide a comprehensive and multidisciplinary insight into the complexity of this disease, reviewing current scientific evidence on COVID-19 management and treatment across several medical specialties involved in the in-hospital care of these patients.

Ocular Findings in COVID-19 Patients: A Review of Direct Manifestations and Indirect Effects on the Eye

The novel pandemic coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has challenged the medical community. While diagnostic and therapeutic efforts have been focused on respiratory complications of the disease, several ocular implications have also emerged. SARS-CoV-2 RNA has been found in tears of the infected patients, and reports suggest that the ocular surface could serve as a portal of entry and a reservoir for viral transmission. Clinically, COVID-19 has been associated with mild conjunctivitis, which can be the first and only symptom of the disease. Subtle retinal changes like hyperreflective lesions in the inner layers on optical coherence tomography (OCT), cotton-wool spots, and microhemorrhages have also been reported. In addition, COVID-19 has been associated with an increased incidence of systemic diseases like diabetes mellitus and Kawasaki disease, which are particularly relevant for ophthalmologists due to their potentially severe ocular manifestations. Several treatment strategies are currently under investigation for COVID-19, but none of them have been proved to be safe and effective to date. Intensive care unit patients, due to risk factors like invasive mechanical ventilation, prone position, and multiresistant bacterial exposure, may develop ocular complications like ocular surface disorders, secondary infections, and less frequently acute ischemic optic neuropathy and intraocular pressure elevation. Among the array of drugs that have shown positive results, the use of hydroxychloroquine and chloroquine has raised a concern due to their well-known retinal toxic effects. However, the risk of retinal toxicity with short-term high-dose use of antimalarials is still unknown. Ocular side effects have also been reported with other investigational drugs like lopinavir-ritonavir, interferons, and interleukin-1 and interleukin-6 inhibitors. The aim of this review was to summarize ophthalmological implications of SARS-CoV-2 infection to serve as a reference for eye care and other physicians for prompt diagnosis and management.

Extra-renal manifestations of atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is a rare and complex disease resulting from abnormal alternative complement activation with a wide range of clinical presentations. Extra-renal manifestations of aHUS can involve many organ systems, including the peripheral and central nervous, gastrointestinal, cardiovascular, integumentary, pulmonary, as well as the eye. While some of these extra-renal manifestations occur in the acute phase of aHUS, some can also occur as long-term sequelae of unopposed complement activation. Extra-renal symptoms are observed in approximately 20% of patients with aHUS, with the incidence of specific organ system complications ranging from a few case reports to 50% of described patients. Careful monitoring for extra-renal involvement is critical in patients with aHUS, as prompt evaluation and management may decrease the risk of high morbidity and mortality associated with aHUS.

Extra-renal manifestations of atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is a rare and complex disease resulting from abnormal alternative complement activation with a wide range of clinical presentations. Extra-renal manifestations of aHUS can involve many organ systems, including the peripheral and central nervous, gastrointestinal, cardiovascular, integumentary, pulmonary, as well as the eye. While some of these extra-renal manifestations occur in the acute phase of aHUS, some can also occur as long-term sequelae of unopposed complement activation. Extra-renal symptoms are observed in approximately 20% of patients with aHUS, with the incidence of specific organ system complications ranging from a few case reports to 50% of described patients. Careful monitoring for extra-renal involvement is critical in patients with aHUS, as prompt evaluation and management may decrease the risk of high morbidity and mortality associated with aHUS.

Complement Factor H Mutation W1206R Causes Retinal Thrombosis and Ischemic Retinopathy in Mice

Single-nucleotide polymorphisms and rare mutations in factor H (FH; official name, CFH) are associated with age-related macular degeneration and atypical hemolytic uremic syndrome, a form of thrombotic microangiopathy. Mice with the FH W1206R mutation (FH^R/R) share features with human atypical hemolytic uremic syndrome. Herein, we report that FH^R/R mice exhibited retinal vascular occlusion and ischemia. Retinal fluorescein angiography demonstrated delayed perfusion and vascular leakage in FH^R/R mice. Optical coherence tomography imaging of FH^R/R mice showed retinal degeneration, edema, and detachment. Histologic analysis of FH^R/R mice revealed retinal thinning, vessel occlusion, as well as degeneration of photoreceptors and retinal pigment epithelium. Immunofluorescence showed albumin leakage from blood vessels into the neural retina, and electron microscopy demonstrated vascular endothelial cell irregularity with narrowing of retinal and choroidal vessels. Knockout of C6, a component of the membrane attack complex, prevented the aforementioned retinal phenotype in FH^R/R mice, consistent with membrane attack complex-mediated pathogenesis. Pharmacologic blockade of C5 also rescued retinas of FH^R/R mice. This FH^R/R mouse strain represents a model for retinal vascular occlusive disorders and ischemic retinopathy. The results suggest complement dysregulation can contribute to retinal vascular occlusion and that an anti-C5 antibody might be helpful for C5-mediated thrombotic retinal diseases.

[Ocular thrombotic microangiopathy in atypical hemolytic-uremic syndrome (a clinical case study)]

The article presents a clinical observation of ocular thrombotic microangiopathy in atypical hemolytic-uremic syndrome - a rare genetic disease characterized by systemic thrombosis caused by uncontrolled activation of alternative complement pathway. A typical manifestation of this ocular lesion in this disease is bilateral Purtscher-like retinopathy. Timely diagnostics of atypical hemolytic-uremic syndrome, including ophthalmologic examination, determines the early start of a highly effective pathogenetic therapy with complement inhibitor eculizumab.

Haemolytic uraemic syndrome

Haemolytic uraemic syndrome is a form of thrombotic microangiopathy affecting predominantly the kidney and characterised by a triad of thrombocytopenia, mechanical haemolytic anaemia, and acute kidney injury. The term encompasses several disorders: shiga toxin-induced and pneumococcus-induced haemolytic uraemic syndrome, haemolytic uraemic syndrome associated with complement dysregulation or mutation of diacylglycerol kinase ɛ, haemolytic uraemic syndrome related to cobalamin C defect, and haemolytic uraemic syndrome secondary to a heterogeneous group of causes (infections, drugs, cancer, and systemic diseases). In the past two decades, experimental, genetic, and clinical studies have helped to decipher the pathophysiology of these various forms of haemolytic uraemic syndrome and undoubtedly improved diagnostic approaches. Moreover, a specific mechanism-based treatment has been made available for patients affected by atypical haemolytic uraemic syndrome due to complement dysregulation. Such treatment is, however, still absent for several other disease types, including shiga toxin-induced haemolytic uraemic syndrome.

Ocular involvement in atypical haemolytic uraemic syndrome

CASE REPORT

The case is presented of a young man with an atypical haemolytic-uraemic syndrome (aHUS), complicated with bilateral serous retinal detachment, cotton wool spots, and a branch artery occlusion. Treatment with plasmapheresis, haemodialysis and systemic eculizumab led to the blood and urine parameters returning to normal, as well as resolution of the retinal anomalies. Genetic analysis show both mutations in complement factor H and C3.

DISCUSSION

Haemolytic-uraemic syndrome (HUS) is a thrombotic microangiopathy characterised by microangiopathic haemolytic anaemia, thrombocytopenia, and acute renal failure. Atypical HUS is caused by genetic mutation of complement system. Ocular involvement is an unusual manifestation of this rare syndrome.