CD8+ T cell-mediated endotheliopathy is a targetable mechanism of neuro-inflammation in Susac syndrome

Fatal Presentation of Susac Syndrome in a Congenitally Deaf Patient With a Cochlear Implant

OBJECTIVE

To report a fatal case of Susac syndrome in a congenitally deaf patient with a cochlear implant and a history of migraines, emphasizing the diagnostic challenges in patients with preexisting conditions.

PATIENT

A 33-year-old male with congenital hearing loss, a cochlear implant, and chronic migraines who presented with mild subacute auditory disturbance and headaches that later progressed to severe encephalopathy.

INTERVENTION

Explantation of a non-magnetic resonance imaging (MRI) compatible cochlear implant followed by MRI, fundoscopy, and the administration of immunosuppressive medications.

MAIN OUTCOME MEASURES

Diagnosis was confirmed by characteristic MRI appearance and the presence of a hemi-retinal artery occlusion.

RESULTS

After weeks of immunosuppressive treatment, the patient died of a global cerebral ischemic event of unknown origin.

CONCLUSIONS

For patients with preexisting sensorineural hearing loss and cochlear implants, Susac syndrome poses a diagnostic challenge. Auditory disturbances in the absence of cochlear implant failure should prompt further evaluation for visual disturbances and encephalopathy. MRI and fundoscopy should be performed to detect other features of the disease.

Risk factors for severe hearing loss in Susac syndrome: A national cohort study

BACKGROUND

Nonreversible hearing loss (HL) is the main sequelae of Susac syndrome (SuS). We aimed to identify risk factors for HL in SuS.

METHODS

The CARESS study is a prospective national cohort study that started in December 2011, including all consecutive patients with SuS referred to the French reference center. The CARESS study was designed with a follow-up including fundoscopy, audiometry, and brain magnetic resonance imaging at 1, 3, 6, and 12 months after diagnosis and then annually for 5 years. The primary outcome was the occurrence at last follow-up of severe HL defined as the loss of 70 dB in at least one ear on audiometry or the need for hearing aids.

RESULTS

Thirty-six patients (female 66.7%, median age 37.5 [range 24.5-42.5] years) included in the clinical study were analyzed for the primary outcome. Thirty-three patients (91.7%) had cochleovestibular involvement at SuS diagnosis including HL >20 dB in at least one ear in 25 cases. At diagnosis, 32 (88.9%), 11 (30.6%), and 7 (19.4%) patients had received steroids, intravenous immunoglobulin, and/or immunosuppressive (IS) drugs, respectively. After a median follow-up of 51.8 [range 29.2-77.6] months, 19 patients (52.8%) experienced severe HL that occurred a median of 13 [range 1.5-29.5] months after diagnosis. Multivariable analysis showed that the odds of severe HL were lower in patients who received IS drugs at diagnosis (OR 0.15, 95% CI 0.01-1.07, p = 0.058).

CONCLUSIONS

Severe HL in SuS is associated with the absence of IS drugs given at diagnosis. Our findings support the systematic use of IS drugs in SuS.

Clinical Characterization and Ancillary Tests in Susac Syndrome: A Systematic Review

Susac syndrome (SuS) is an orphan microangiopathic disease characterized by a triad of encephalopathy, visual disturbances due to branch retinal artery occlusions, and sensorineuronal hearing loss. Our previous systematic review on all cases of SuS reported until 2012 allowed for a better understanding of clinical presentation and diagnostic findings. Based on these data, we suggested diagnostic criteria in 2016 to allow early diagnosis and treatment of SuS. In view of the accumulation of new SuS cases reported in the last 10 years and improved diagnostic tools, we here aimed at updating the demographic and clinical features of SuS and to review the updated ancillary tests being used for SuS diagnosis. Therefore, based on the 2016 criteria, we systematically collected and evaluated data on SuS published from January 2013 to March 2022.

CD28null T cells in aging and diseases: From biology to assessment and intervention

CD28null T cells, an atypical subset characterized by the loss of CD28 costimulatory molecule expression, exhibit functional variants and progressively expand with age. Moreover, T cells with these phenotypes are found in both typical and atypical humoral immune responses. Consequently, they accumulate during infectious diseases, autoimmune disorders, cardiovascular conditions, and neurodegenerative ailments. To provide an in-depth review of the current knowledge regarding CD28null T cells, we specifically focus on their phenotypic and functional characteristics as well as their physiological roles in aging and diseases. While uncertainties regarding the clinical utility remains, we will review the following two crucial research perspectives to explore clinical translational applications of the research on this specific T cell subset: 1) addressing the potential utility of CD28null T cells as immunological markers for prognosis and adverse outcomes in both aging and disease, and 2) speculating on the potential of targeting CD28null T cells as an interventional strategy for preventing or delaying immune aging processes and disease progression.

Cognitive outcomes in Susac syndrome: A 2-year neuropsychological follow-up study

BACKGROUND AND PURPOSE

Susac syndrome (SuS) is a rare, autoimmune, neurological disease characterized by a clinical triad of branch retinal artery occlusion, sensorineural hearing loss and encephalopathy. Neuropsychological functioning in SuS is little researched and the prevalence, nature, and evolution over time of cognitive deficits in SuS remain unclear. This study aimed to better understand the long-term neuropsychological outcomes of patients with SuS.

METHODS

Thirteen patients with SuS (mean [SD] age 39.5 [11.1] years) were enrolled at the Ghent University Hospital by their treating neurologist. The cognitive functioning and emotional well-being of each patient was evaluated by means of a thorough neuropsychological test battery at baseline and after 2 years. Follow-up testing after 2 years was performed in 11 patients (mean [SD] age 42.2 [11.5] years).

RESULTS

Patients showed normal neuropsychological test results at a group level, both at baseline and follow-up testing. Significant improvements over time were found for information processing speed, verbal recognition, and semantic and phonological fluency. Individual test results showed interindividual variability at baseline, with most impairments being in attention, executive functioning and language, which improved after a 2-year period. In addition, patients reported significantly lower mental and physical well-being, both at baseline and follow-up testing.

CONCLUSIONS

Our results suggest that neuropsychological dysfunction in SuS is limited at a group level and improves over time. Nonetheless, individual test results reveal interindividual variability, making cognitive screening essential. Furthermore, a high psycho-emotional burden of the disease was reported, for which screening and follow-up are necessary.

Blood and CSF findings of cellular immunity in anti-NMDAR encephalitis

OBJECTIVES

To investigate the immunopathogenic mechanisms of anti-N-methyl-D-aspartate receptor encephalitis (NMDAR-E) by characterizing the changes of immune cells in both peripheral blood (PB) and cerebrospinal fluid (CSF) of patients with NMDAR-E.

METHODS

Cytology and flow cytometry were used to explore and compare different immunological parameters in PB and CSF of patients with NMDAR-E, viral encephalitis (VE) and healthy volunteers. Moreover, different models were established to assess the possibility of identifying NMDAR-E patients based on PB and CSF parameters.

RESULTS

The neutrophil counts and monocyte-to-lymphocyte ratios (MLR) in PB are higher in NMDAR-E patients than in both VEs and controls (P < 0.001, respectively), while the percentages of CD3 + T, CD4 + T lymphocytes, and the leukocytes count in CSF were lower in NMDAR-Es than in VEs (P < 0.01, respectively). The higher percentages of CD8 + T cells in blood and CSF were both correlated with more severe NMDAR-E (P < 0.05, respectively). The poor neurological status group had significantly higher PB leukocytes but lower CSF leukocyte count (P < 0.05). Longitudinal observations in patients with NMDAR-E showed a decreasing trend of leukocyte count, neutrophils count, neutrophil-to-monocyte ratios (NMR), and neutrophil-to-lymphocyte ratios (NLR) with the gradual recovery of neurological function.

CONCLUSIONS

The expression patterns of T lymphocyte subsets were different in patients with NMDAR-E and viral encephalitis. The changing trends of leukocyte and lymphocyte populations in peripheral blood and cerebrospinal fluid may provide clues for the diagnosis of different types of encephalitides, including NMDARE, and can be used as immunological markers to assess and predict the prognosis.

The Interplay between Ferroptosis and Neuroinflammation in Central Neurological Disorders

Central neurological disorders are significant contributors to morbidity, mortality, and long-term disability globally in modern society. These encompass neurodegenerative diseases, ischemic brain diseases, traumatic brain injury, epilepsy, depression, and more. The involved pathogenesis is notably intricate and diverse. Ferroptosis and neuroinflammation play pivotal roles in elucidating the causes of cognitive impairment stemming from these diseases. Given the concurrent occurrence of ferroptosis and neuroinflammation due to metabolic shifts such as iron and ROS, as well as their critical roles in central nervous disorders, the investigation into the co-regulatory mechanism of ferroptosis and neuroinflammation has emerged as a prominent area of research. This paper delves into the mechanisms of ferroptosis and neuroinflammation in central nervous disorders, along with their interrelationship. It specifically emphasizes the core molecules within the shared pathways governing ferroptosis and neuroinflammation, including SIRT1, Nrf2, NF-κB, Cox-2, iNOS/NO·, and how different immune cells and structures contribute to cognitive dysfunction through these mechanisms. Researchers' findings suggest that ferroptosis and neuroinflammation mutually promote each other and may represent key factors in the progression of central neurological disorders. A deeper comprehension of the common pathway between cellular ferroptosis and neuroinflammation holds promise for improving symptoms and prognosis related to central neurological disorders.

Endothelial cells and macrophages as allies in the healthy and diseased brain

Diseases of the central nervous system (CNS) are often associated with vascular disturbances or inflammation and frequently both. Consequently, endothelial cells and macrophages are key cellular players that mediate pathology in many CNS diseases. Macrophages in the brain consist of the CNS-associated macrophages (CAMs) [also referred to as border-associated macrophages (BAMs)] and microglia, both of which are close neighbours or even form direct contacts with endothelial cells in microvessels. Recent progress has revealed that different macrophage populations in the CNS and a subset of brain endothelial cells are derived from the same erythromyeloid progenitor cells. Macrophages and endothelial cells share several common features in their life cycle-from invasion into the CNS early during embryonic development and proliferation in the CNS, to their demise. In adults, microglia and CAMs have been implicated in regulating the patency and diameter of vessels, blood flow, the tightness of the blood-brain barrier, the removal of vascular calcification, and the life-time of brain endothelial cells. Conversely, CNS endothelial cells may affect the polarization and activation state of myeloid populations. The molecular mechanisms governing the pas de deux of brain macrophages and endothelial cells are beginning to be deciphered and will be reviewed here.

Central intra-lesional iron deposits as a possible novel imaging marker at 7 Tesla MRI in Susac Syndrome - an exploratory study

BACKGROUND

Susac syndrome (SuS) is a rare autoimmune disease that leads to hearing impairment, visual field deficits, and encephalopathy due to an occlusion of precapillary arterioles in the brain, retina, and inner ear. Given the potentially disastrous outcome and difficulties in distinguishing SuS from its differential diagnoses, such as multiple sclerosis (MS), our exploratory study aimed at identifying potential new SuS-specific neuroimaging markers.

METHODS

Seven patients with a definite diagnosis of SuS underwent magnetic resonance imaging (MRI) at 7 Tesla (7T), including T2* weighted and quantitative susceptibility mapping (QSM) sequences. T2 weighted hyperintense lesions were analyzed with regard to number, volume, localization, central vein sign, T1 hypointensity, and focal iron deposits in the center of SuS lesions ("iron dots"). Seven T MRI datasets from the same institute, comprising 75 patients with, among others, MS, served as controls.

RESULTS

The "iron dot" sign was present in 71.4% (5/7) of the SuS patients, compared to 0% in our control cohort. Thus, sensitivity was 71.4% and specificity 100%. A central vein sign was only incidentally detected.

CONCLUSION

We are the first to demonstrate this type of "iron dot" lesions on highly resolving 7T T2*w and QSM images in vivo as a promising neuroimaging marker of SuS, corroborating previous histopathological ex vivo findings.

Diffuse Cerebral Edema With Uncal Herniation Leading to Brain Death in Patient With Fulminant Susac syndrome: Rare Complication of Rare Disease

Susac Syndrome was first described as an inflammatory microangiopathy of the brain and retina. Since then, multiple articles have been published in attempts to improve the understanding of this rare disease. Clinically Susac Syndrome is known to present with triad of encephalopathy, sensorineural hearing loss and branch of retinal artery occlusion (BRAO), along with characteristic "snowball" or "spoke" appearing white matter lesions of the corpus callosum. It has been characterized by vast heterogeneity in terms of its presenting symptoms, severity, and clinical course. Although subset of patients present with severe forms of Susac Syndrome and can develop prominent residual neurologic deficits, it has been reported to be mostly non-life-threatening and only few fatal cases have been described in the literature. Based on the available case reports with fatal outcome, mortality has been related to the systemic complications either during acute disease flare or during chronic-progressive phase. We describe a case of fulminant Susac Syndrome complicated by the sudden and rapid progression of diffuse cerebral edema leading to brain herniation and ultimate brain death, in order to increase awareness of this rare and catastrophic complication.

Clinical characteristics and treatment approaches in patients with Susac syndrome: a scoping review of cases

BACKGROUND

Susac syndrome (SuS) is a rare disease characterized by encephalopathy, hearing impairment and visual disturbances. Immunosuppressive treatments are used based on the hypothesis that an autoimmune endotheliopathy drives the disease. However, a solid evidence-based treatment approach is lacking. The aim of this review is to provide an overview of patient characteristics, disease course and treatment patterns related to successful outcome that have been reported in literature since 2013.

METHODS

Three reviewers conducted a systematic literature search in February 2022. The primary outcome was treatment used, derived from cases classified as probable or definite SuS, describing successful treatment outcome (i.e. no signs of disease activity for ≥ 1 month). Secondary outcomes were time-to-relapse and follow-up time. Published case reports and case series were included. Various clinical characteristics and treatment(s) were extracted and categorized into different phases of treatment.

RESULTS

A total of 810 records was identified. 120 articles met inclusion criteria and 161 cases were extracted. Of these, 151 cases were classified as probable or definite SuS and included in the final analysis. Number of combinations of treatments used per treatment phase were: 6 empirically, 35 after confirmed diagnosis, 43 for maintenance treatment, 22 after relapse, 18 during maintenance post-relapse. Median follow-up time was 12.3 months (0.5; 120) and median time to relapse was 4 months (1; 120).

CONCLUSION

This scoping review summarizes treatment approaches in patients with SuS, highlighting variability. International efforts to collect clinical, imaging and treatment data from patients with SuS in registries are needed, in order to provide less biased and long-term follow-up information on treatment response, predictors of relapse and patient outcomes. This may lead to more evidence-based therapeutic approaches.

Susac syndrome: neurological update (clinical features, long-term observational follow-up and management of sixteen patients)

Susac syndrome is a likely autoimmune microangiopathy affecting the brain, retina and inner ear. Due to the rarity of this condition, diagnosis and treatment can be challenging. Diagnosis is based on the presence of the clinical triad of central nervous system dysfunction, branch retinal artery occlusions and sensorineural hearing loss. Typical MRI findings of callosal and peri-callosal lesions may assist in diagnosis. Clinical course can be monophasic, polycyclic or chronic continuous. It is important to look out for red flags to attain an accurate diagnosis and follow a therapeutic algorithm based on severity of the disease and response to treatment. Patients are treated with steroids and immunosuppressive agents with a variable response. Early aggressive treatment especially in severe cases, may help in preventing relapses and morbidity/disability. This study highlights important diagnostic features and proposes a treatment algorithm based on clinical experience from management of 16 patients from 2 neuroscience centres in the UK since 2007, who were followed up over a long period of 3-15 years.

Learning CNS immunopathology from therapeutic interventions

Modulation of immune cell trafficking across the blood-brain barrier has not only introduced a therapeutic avenue for multiple sclerosis (MS) but also represents an example of reverse translational medicine. Data from clinical trials of drugs such as natalizumab and fingolimod have revealed the involvement of different compartments in relapsing versus non-relapsing MS immune biology, contributed to our understanding of central nervous system (CNS) immune surveillance, and stimulated new fields of research. Here, we discuss the results of these trials, as well as patient biomaterial-based scientific projects, and how both have informed our understanding of CNS immunopathology.

Pathogenetic mechanisms and treatment targets in cerebral malaria

Malaria, the most prevalent mosquito-borne infectious disease worldwide, has accompanied humanity for millennia and remains an important public health issue despite advances in its prevention and treatment. Most infections are asymptomatic, but a small percentage of individuals with a heavy parasite burden develop severe malaria, a group of clinical syndromes attributable to organ dysfunction. Cerebral malaria is an infrequent but life-threatening complication of severe malaria that presents as an acute cerebrovascular encephalopathy characterized by unarousable coma. Despite effective antiparasite drug treatment, 20% of patients with cerebral malaria die from this disease, and many survivors of cerebral malaria have neurocognitive impairment. Thus, an important unmet clinical need is to rapidly identify people with malaria who are at risk of developing cerebral malaria and to develop preventive, adjunctive and neuroprotective treatments for cerebral malaria. This Review describes important advances in the understanding of cerebral malaria over the past two decades and discusses how these mechanistic insights could be translated into new therapies.

Lauric acid provides neuroprotection against oxidative stress in mouse model of hyperglycaemic stroke

During ischemic stroke, higher glucose level linked worse outcomes were reported even in patients without pre-existing diabetes. Evidence suggest that such worse stroke outcomes were mainly due to production of reactive, toxic glucose metabolites that expands oxidative damage inside the brain. As a consequence of high oxidative stress, microvasculature structures and tight junctions compromised their functionally, infarct volume expands and brain edema exacerbates. In a mouse model of ischemic stroke with induced acute hyperglycaemia, Lauric acid (LA) as a natural saturated fatty acid demonstrated neuroprotection by attenuating infarct volume and brain edema. In addition, in the ipsilateral hyperglycaemic brain, the LA significantly increased the expression of tight junction representative protein (occludin) as well as anti-oxidative markers; Manganese superoxide dismutase (Mn) SOD, Extracellular superoxide dismutase (Ec-SOD) and nuclear factor-erythroid factor 2-related factor 2 (Nrf2) in the ipsilateral region against hyperglycemic ischemic stroke. LA treated animals showed a significant reduction in the production of lipid peroxidation products (4-HNE) in the microvascular structures, maintained the blood brain barrier (BBB) integrity. LA linked neuroprotective outcomes were further confirmed by behavioral tests, where functional outcomes and motor coordination were improved significantly. Furthermore, LA treatment enhanced food intake, decreased mortality rate, and net body weight loss. Conclusively, LA modulated ischemic insult exacerbated by hyperglycemia and provided neuroprotection.

Clinically relevant increases in serum neurofilament light chain and glial fibrillary acidic protein in patients with Susac syndrome

BACKGROUND AND PURPOSE

Serum levels of neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) are promising neuro-axonal damage and astrocytic activation biomarkers. Susac syndrome (SS) is an increasingly recognized neurological condition and biomarkers that can help assess and monitor disease evolution are highly needed for the adequate management of these patients. sNfL and sGFAP levels were evaluated in patients with SS and their clinical relevance in the relapse and remission phase of the disease was assessed.

METHODS

As part of a multicentre study that enrolled patients diagnosed with SS from six international centres, sNfL and sGFAP levels were assessed in 22 SS patients (nine during a relapse and 13 in remission) and 59 age- and sex-matched healthy controls using SimoaTM assay Neurology 2-Plex B Kit.

RESULTS

Serum NfL levels were higher than those of healthy controls (p < 0.001) in SS patients and in both subgroups of patients in relapse and in remission (p < 0.001 for both), with significantly higher levels in relapse than in remission (p = 0.008). sNfL levels showed a negative correlation with time from the last relapse (r = -0.663; p = 0.001). sGFAP levels were slightly higher in the whole group of patients than in healthy controls (p = 0.046) and were more pronounced in relapse than in remission (p = 0.013).

CONCLUSION

In SS patients, both sNFL and sGFAP levels increased compared with healthy controls. Both biomarkers had higher levels during clinical relapse and much lower levels in remission. sNFL was shown to be time sensitive to clinical changes and can be useful to monitor neuro-axonal damage in SS.

CD8+ T cell depletion prevents neuropathology in a mouse model of globoid cell leukodystrophy

Globoid cell leukodystrophy (GLD) or Krabbe's disease is a fatal genetic demyelinating disease of the central nervous system caused by loss-of-function mutations in the galactosylceramidase (galc) gene. While the metabolic basis for disease is known, the understanding of how this results in neuropathology is not well understood. Herein, we report that the rapid and protracted elevation of CD8+ cytotoxic T lymphocytes occurs coincident with clinical disease in a mouse model of GLD. Administration of a function-blocking antibody against CD8α effectively prevented disease onset, reduced morbidity and mortality, and prevented CNS demyelination in mice. These data indicate that subsequent to the genetic cause of disease, neuropathology is driven by pathogenic CD8+ T cells, thus offering novel therapeutic potential for treatment of GLD.

Cytolytic CD8+ T cell response to SARS-CoV-2 and non-SARS-CoV-2-related viruses is associated with severe manifestation of COVID-19

Little is known about the CD8+ T cell functionality in the coronavirus disease 2019 (COVID-19). Therefore, we examined twenty-five hospitalized COVID-19 patients with moderate (MD) or severe disease (SD) as well as seventeen SARS-CoV-2-unexposed persons regarding the cytolytic and cytokine-producing reactivity of their CD8+ T cells. Reactive CD8+ T cells were detectable in 90% of the unexposed persons, confirming high cross-reactive immune memory in the general population. Compared to unexposed persons and MD patients, SD patients had higher numbers of SARS-CoV-2 reactive CD8+ T cells with cytolytic function that can simultaneously produce inflammatory cytokines. In addition, SD patients showed higher CD8+ T cell reactivity against non-SARS-CoV-2-related viruses, which was mainly mediated by cytolytic response. Sequence alignments showed that cross-reactivities with the Spike protein could contribute to the expansion of such cells. Since insufficiently regulated cytolytic CD8+ T cells can damage peripheral and vascular tissue structures, high levels of both SARS-CoV-2-reactive and heterologously activated cytolytic CD8+ T cells could favor severe disease progression.

Case report: Granzyme-B expression by T- and B- cells during severe AQP4-positive Neuromyelitis Optica spectrum disorder with fatal venous thromboembolism outcome

Background

The expression of serine protease granzyme-B (GzmB) by circulating CD8+ T lymphocytes has been recently suggested as a biomarker for poor immunotherapy response and severe disability in patients with Neuromyelitis Optica spectrum disorders (NMOSD). In parallel, venous thromboembolism (VTE) has been reported mainly in NMOSD patients exhibiting transverse myelitis.

Case presentation

Here, we describe an Aquaporin-4 positive (AQP4-positive) NMOSD patient who showed short myelitis (SM) and experienced a fatal pulmonary thromboembolism/lower extremity deep vein thrombosis during anti-CD20 treatment. Flow cytometry analyses from the peripheral blood revealed an enhanced cytotoxic behavior through circulating CD8+GzmB+ T, CD4+GzmB+ T lymphocytes, and residual CD19+GzmB+ B cells.

Conclusions

Fatal VTE may be a rare outcome, particularly in patients exhibiting SM, and may share poorly understood immunological mechanisms with AQP4-positive NMOSD severity.

The role of the CD8+ T cell compartment in ageing and neurodegenerative disorders

CD8+ lymphocytes are adaptive immunity cells with the particular function to directly kill the target cell following antigen recognition in the context of MHC class I. In addition, CD8+ T cells may release pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), and a plethora of other cytokines and chemoattractants modulating immune and inflammatory responses. A role for CD8+ T cells has been suggested in aging and several diseases of the central nervous system (CNS), including Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, limbic encephalitis-induced temporal lobe epilepsy and Susac syndrome. Here we discuss the phenotypic and functional alterations of CD8+ T cell compartment during these conditions, highlighting similarities and differences between CNS disorders. Particularly, we describe the pathological changes in CD8+ T cell memory phenotypes emphasizing the role of senescence and exhaustion in promoting neuroinflammation and neurodegeneration. We also discuss the relevance of trafficking molecules such as selectins, mucins and integrins controlling the extravasation of CD8+ T cells into the CNS and promoting disease development. Finally, we discuss how CD8+ T cells may induce CNS tissue damage leading to neurodegeneration and suggest that targeting detrimental CD8+ T cells functions may have therapeutic effect in CNS disorders.

Effects of a Small-Molecule Perforin Inhibitor in a Mouse Model of CD8 T Cell-Mediated Neuroinflammation

BACKGROUND AND OBJECTIVES

Alteration of the blood-brain barrier (BBB) at the interface between blood and CNS parenchyma is prominent in most neuroinflammatory diseases. In several neurologic diseases, including cerebral malaria and Susac syndrome, a CD8 T cell-mediated targeting of endothelial cells of the BBB (BBB-ECs) has been implicated in pathogenesis.

METHODS

In this study, we used an experimental mouse model to evaluate the ability of a small-molecule perforin inhibitor to prevent neuroinflammation resulting from cytotoxic CD8 T cell-mediated damage of BBB-ECs.

RESULTS

Using an in vitro coculture system, we first identified perforin as an essential molecule for killing of BBB-ECs by CD8 T cells. We then found that short-term pharmacologic inhibition of perforin commencing after disease onset restored motor function and inhibited the neuropathology. Perforin inhibition resulted in preserved BBB-EC viability, maintenance of the BBB, and reduced CD8 T-cell accumulation in the brain and retina.

DISCUSSION

Therefore, perforin-dependent cytotoxicity plays a key role in the death of BBB-ECs inflicted by autoreactive CD8 T cells in a preclinical model and potentially represents a therapeutic target for CD8 T cell-mediated neuroinflammatory diseases, such as cerebral malaria and Susac syndrome.

Granzyme B + CD8 + T cells with terminal differentiated effector signature determine multiple sclerosis progression

BACKGROUND

Multiple sclerosis (MS) leads to demyelination and neurodegeneration with autoimmune responses in central nervous system. Patients begin with a relapsing-remitting (RR) course, and more than 80% of them may advance to secondary progressive MS (SPMS), which is characteristic for the gradual decline of neurological functions without demonstrated treating method to prevent. This study aims to investigate the contribution of peripheral CD8 + T cells during the conversion from RRMS to SPMS, as well as reveal potential diagnostic signature in distinguishing SPMS.

METHODS

Single-cell RNA sequencing was employed to reveal the heterogeneity of CD8 + T cells between SPMS and RRMS. In addition, flow cytometry was used to further characterized CD8 + T cell dynamic changes in patients. T cell receptor sequencing was performed to detect the clonal expansion of MS. Using Tbx21 siRNA, T-bet was confirmed to manipulate GzmB expression. The correlation between GzmB + CD8 + T cell subsets and clinical characteristics of MS and their potential diagnostic value for SPMS were evaluated by generalized linear regression models and receiver operating characteristic (ROC) curve respectively.

RESULTS

Other than diminished naïve CD8 + T cell, elevating of activated CD8 + T cell subsets were observed in SPMS patients. Meanwhile, this aberrant amplified peripheral CD8 + T cells not only exhibited terminal differentiated effector (EMRA) phenotype with GzmB expression, but also possessed distinct trajectory from clonal expansion. In addition, T-bet acted as a key transcriptional factor that elicited GzmB expression in CD8 + T_EMRA cells of patients with SPMS. Finally, the expression of GzmB in CD8 + T cells was positively correlated with disability and progression of MS, and could effectively distinguish SPMS from RRMS with a high accuracy.

CONCLUSIONS

Our study mapped peripheral immune cells of RRMS and SPMS patients and provided an evidence for the involvement of GzmB + CD8 + T_EMRA cells in the progression of MS, which could be used as a diagnostic biomarker for distinguishing SPMS from RRMS.

Antigen recognition detains CD8+ T cells at the blood-brain barrier and contributes to its breakdown

Blood-brain barrier (BBB) breakdown and immune cell infiltration into the central nervous system (CNS) are early hallmarks of multiple sclerosis (MS). High numbers of CD8+ T cells are found in MS lesions, and antigen (Ag) presentation at the BBB has been proposed to promote CD8+ T cell entry into the CNS. Here, we show that brain endothelial cells process and cross-present Ag, leading to effector CD8+ T cell differentiation. Under physiological flow in vitro, endothelial Ag presentation prevented CD8+ T cell crawling and diapedesis resulting in brain endothelial cell apoptosis and BBB breakdown. Brain endothelial Ag presentation in vivo was limited due to Ag uptake by CNS-resident macrophages but still reduced motility of Ag-specific CD8+ T cells within CNS microvessels. MHC class I-restricted Ag presentation at the BBB during neuroinflammation thus prohibits CD8+ T cell entry into the CNS and triggers CD8+ T cell-mediated focal BBB breakdown.

Use of disease assessment tools to increase the value of case reports on Susac syndrome: two case reports

BACKGROUND

Susac syndrome is an immune-mediated, ischemia-producing, occlusive microvascular endotheliopathy that threatens the brain, retina, and inner ear. There is a need for disease assessment tools that can help clinicians and patients to more easily, accurately, and uniformly track the clinical course and outcome of Susac syndrome. Ideally, such tools should simultaneously facilitate the clinical care and study of Susac syndrome and improve the value of future case reports. To meet this need, two novel clinical assessment tools were developed: the Susac Symptoms Form and the Susac Disease Damage Score. The former is a comprehensive self-report form that is completed by patients/families to serially document the clinical status of a patient. The latter documents the extent of damage perceived by individual patients/families and their physicians. Both forms were initially trialed with two particularly representative and instructive patients. The results of this trial are shared in this report.

CASE PRESENTATION

Patient 1 is a 21-year-old Caucasian female who presented with an acute onset of headache, paresthesias, cognitive dysfunction, and emotional lability. Patient 2 is a 14-year-old Caucasian female who presented with an acute onset of headache, cognitive dysfunction, urinary incontinence, ataxia, and personality change. Both patients fulfilled criteria for a definite diagnosis of Susac syndrome: both eventually developed brain, retinal, and inner ear involvement, and both had typical "snowball lesions" on magnetic resonance imaging. The Susac Symptoms Form documented initial improvement in both patients, was sufficiently sensitive in detecting a subsequent relapse in the second patient, and succinctly documented the long-term clinical course in both patients. The Disease Damage Score documented minimal disease damage in the first patient and more significant damage in the second.

CONCLUSIONS

The Susac Symptoms Form and the Disease Damage Score are useful disease assessment tools, both for clinical care and research purposes. Their use could enhance the value of future case reports on Susac syndrome and could improve opportunities to learn from a series of such reports.

Atypical clinical and novel radiological findings in Susac syndrome: Experience from a large monocentric cohort

Susac syndrome (SuS) is a rare immune-mediated endotheliopathy that affects the brain, retina and inner ear and is characterised by the variable clinical triad of encephalopathy, visual and vestibulocochlear dysfunction. Here, we present clinical and paraclinical data of 19 SuS patients followed at Ghent University Hospital and highlight some atypical clinical and novel radiological findings. Our findings suggest that spinal involvement expands the clinical phenotype of SuS. We further introduce dark blood sequences as a more sensitive technique to detect radiological disease activity in SuS. Our data add to the current understanding of the diagnosis, monitoring and treatment of SuS.

Fulminant Susac syndrome-a rare cause of coma: The history of the fatal course in a young man

Susac syndrome is a rare microangiopathy of indeterminate etiology, presumably autoimmune, characterized by a triad of encephalopathy, sensorineural hearing loss, and branch retinal artery occlusions occurring predominantly in women. The onset and progression patterns are multiple, mainly of three modes. Fulminant evolution is exceptional, rarely reported across literature. We report through this case a Susac syndrome in a young man in whom evolution was fatal. Magnetic resonance imaging is essential to raise the diagnosis and for follow-up, with almost pathognomonic findings, all the more useful as the clinical triad is usually incomplete and as the encephalopathy is the most limiting of the symptoms.

Diagnostic and therapeutic approach to adult central nervous system vasculitis

The clinical manifestations of central nervous system (CNS) vasculitis are highly variable. In the absence of a positive CNS biopsy, CNS vasculitis is particularly suspected when markers of both vascular disease and inflammation are present. To facilitate the clinical and therapeutic approach to this rare condition, CNS vasculitis can be classified according to the size of the involved vessels. Vascular imaging is used to identify medium vessel disease. Small vessel disease can only be diagnosed with a CNS biopsy. Medium vessel vasculitis usually presents with focal neurological signs, while small vessel vasculitis more often leads to cognitive deficits, altered level of consciousness and seizures. Markers of CNS inflammation include cerebrospinal fluid pleocytosis or elevated protein levels, and vessel wall, parenchymal or leptomeningeal enhancement. The broad range of differential diagnoses of CNS vasculitis can be narrowed based on the disease subtype. Common mimickers of medium vessel vasculitis include intracranial atherosclerosis and reversible cerebral vasoconstriction syndrome. The diagnostic workup aims to answer two questions: is the neurological presentation secondary to a vasculitic process, and if so, is the vasculitis primary (i.e., primary angiitis of the CNS) or secondary (e.g., to a systemic vasculitis, connective tissue disorder, infection, malignancy or drug use)? In primary angiitis of the CNS, glucocorticoids and cyclophosphamide are most often used for induction therapy, but rituximab may be an alternative. Based on the available evidence, all patients should receive maintenance immunosuppression. A multidisciplinary approach is necessary to ensure an accurate and timely diagnosis and to improve outcomes for patients with this potentially devastating condition.

Effector Memory-Expressing CD45RA (TEMRA) CD8+ T Cells from Kidney Transplant Recipients Exhibit Enhanced Purinergic P2X4 Receptor-Dependent Proinflammatory and Migratory Responses

BACKGROUND

The mechanisms regulating CD8+ T cell migration to nonlymphoid tissue during inflammation have not been fully elucidated, and the migratory properties of effector memory CD8+ T cells that re-express CD45RA (TEMRA CD8+ T cells) remain unclear, despite their roles in autoimmune diseases and allotransplant rejection.

METHODS

We used single-cell proteomic profiling and functional testing of CD8+ T cell subsets to characterize their effector functions and migratory properties in healthy volunteers and kidney transplant recipients with stable or humoral rejection.

RESULTS

We showed that humoral rejection of a kidney allograft is associated with an accumulation of cytolytic TEMRA CD8+ T cells in blood and kidney graft biopsies. TEMRA CD8+ T cells from kidney transplant recipients exhibited enhanced migratory properties compared with effector memory (EM) CD8+ T cells, with enhanced adhesion to activated endothelium and transmigration in response to the chemokine CXCL12. CXCL12 directly triggers a purinergic P2×4 receptor-dependent proinflammatory response of TEMRA CD8+ T cells from transplant recipients. The stimulation with IL-15 promotes the CXCL12-induced migration of TEMRA and EM CD8+ T cells and promotes the generation of functional PSGL1, which interacts with the cell adhesion molecule P-selectin and adhesion of these cells to activated endothelium. Although disruption of the interaction between functional PSGL1 and P-selectin prevents the adhesion and transmigration of both TEMRA and EM CD8+ T cells, targeting VLA-4 or LFA-1 (integrins involved in T cell migration) specifically inhibited the migration of TEMRA CD8+ T cells from kidney transplant recipients.

CONCLUSIONS

Our findings highlight the active role of TEMRA CD8+ T cells in humoral transplant rejection and suggest that kidney transplant recipients may benefit from therapeutics targeting these cells.

Granzyme B in circulating CD8+ T cells as a biomarker of immunotherapy effectiveness and disability in neuromyelitis optica spectrum disorders

BACKGROUND AND OBJECTIVE

Neuromyelitis optica spectrum disorders (NMOSD) are chronical inflammatory demyelinating diseases of the central nervous system (CNS) and the underlying mechanism remains unclear. Several recent studies have demonstrated that T cells play a pivotal role in the pathogenesis of NMOSD.In this study, we investigated CD8+ T cell phenotypes and levels of the cytotoxic protein granzyme B (GzmB), as well as their potential clinical application in NMOSD.

METHODS

In this study, 90 peripheral blood samples were collected from 59 NMOSD patients with seropositive anti-aquaporin-4 (AQP4) antibodies and 31 sex- and age-matched healthy donors (HDs). Flow cytometry was used to detect circulating levels of GzmB and CD8+ T cell subpopulations, including naïve (TN, CCD7+CD45RA+), central memory (TCM, CCD7+CD45RA-), effector memory (TEM, CCD7-CD45RA-), terminal differentiation effector memory cells (TEMRA, CCD7-CD45RA+) in both groups. The associations between GzmB levels in CD8+T cells and clinical characteristics of NMOSD were evaluated.

RESULTS

NMOSD patients exhibited significantly decreased proportions of CD8+TN cells and increased proportions of highly differentiated CD8+T cells (TEMRA) compared with HDs. In addition, levels of GzmB in CD8+ T cells were markedly higher in NMOSD patients than in HDs. Moreover, we observed that high proportions of GzmB-expressing CD8+ T cells were more common in patients with a poor response to immunotherapies, and showed a good potential to distinguish poor responders from responders (ACU=0.89). Clinical correlation analysis indicated that high levels of GzmB in CD8+ T cells were not only related to severe disability but also significantly associated with increased serum levels of neurofilament light (NFL) and glial fibrillary acidic protein (GFAP). Multivariate linear regression analyses further suggested that GzmB expression in CD8+ T cells was predominantly associated with disability and immunotherapy effectiveness in NMOSD, independent of the sex, age, and disease phase. Transcription factor T-bet in CD8+ T cells were also significantly elevated in NMOSD and were associated with increasing number of circulating CD8+TEMRA cells and GzmB-expressing CD8+T cells.

CONCLUSIONS

Our study support the involvement of GzmB-expressing CD8+ T cells in the inflammatory response in patients with NMOSD and provide a potential biomarker for disease immunotherapy effectiveness and disability progression.

Susac Syndrome: Description of a Single-Centre Case Series

This study describes the clinical characteristics, diagnostic results, treatment regimens, and clinical course of a cohort of patients with Susac syndrome (SS). It is a retrospective observational study of all patients with the diagnosis of SS evaluated at the Hospital Clinic (Barcelona, Spain) between March 2006 and November 2020. Nine patients were diagnosed with SS. The median time from the onset of the symptoms to diagnosis was five months (IQR 9.0), and the median follow-up time was 44 months (IQR 63.5). There was no clear predominance of sex, and mean age of symptoms onset was 36 years (range 19–59). Six patients (67%) presented with incomplete classical clinical triad, but this eventually developed in six patients during the disease course. Encephalopathy, focal neurological signs, visual disturbances, and hearing loss were the most frequent manifestations. Brain magnetic resonance imaging showed callosal lesions in all patients. Most were in remission within two years. Only four patients met the proposed criteria for definite SS. When SS is suspected, a detailed diagnostic workup should be performed and repeated over time to identify the clinical manifestations that will lead to a definite diagnosis.

Small Molecule Inhibitors of Lymphocyte Perforin as Focused Immunosuppressants for Infection and Autoimmunity

New drugs that precisely target the immune mechanisms critical for cytotoxic T lymphocyte (CTL) and natural killer (NK) cell driven pathologies are desperately needed. In this perspective, we explore the cytolytic protein perforin as a target for therapeutic intervention. Perforin plays an indispensable role in CTL/NK killing and controls a range of immune pathologies, while being encoded by a single copy gene with no redundancy of function. An immunosuppressant targeting this protein would provide the first-ever therapy focused specifically on one of the principal cell death pathways contributing to allotransplant rejection and underpinning multiple autoimmune and postinfectious diseases. No drugs that selectively block perforin-dependent cell death are currently in clinical use, so this perspective will review published novel small molecule inhibitors, concluding with in vivo proof-of-concept experiments performed in mouse models of perforin-mediated immune pathologies that provide a potential pathway toward a clinically useful therapeutic agent.

Involuntary crying episodes with Susac's syndrome-a rare presentation of a rare disease: a case report

BACKGROUND

In this case, we reported the pseudobulbar affect (PBA) in a patient with Susac's syndrome-a rare condition that was caused by a rare syndrome. Previous case reports of Susac syndrome described psychiatric symptoms such as emotional disturbances or personality changes. Only a few case reports have reported psychiatric disorders in patients with Susac's syndrome. There were no reported cases of Susac syndrome with PBA as an initial presentation.

CASE PRESENTATION

Our patient was 56 years old and presented with involuntary crying, left-sided headache, left-sided hearing loss, and tinnitus. Brain MRI showed numerous areas of restricted diffusion and enhancement involving the corpus callosum, bilateral hemispheres, and brainstem. Ophthalmological evaluation showed bilateral branch retinal artery occlusion. She was diagnosed with Susac's syndrome and PBA. She was treated with cyclophosphamide and dextromethorphan hydrobromide/quinidine sulfate with excellent recovery. This is a 2-year clinical course.

DISCUSSION AND CONCLUSIONS

Recognition of the clinical presentation of Susac's syndrome and PBA with early diagnosis and treatment are the keys to preventing further disability and impact on patients and their families.

Susac's syndrome - A new ocular finding and disease outcome

BACKGROUND

Susac's syndrome, a rare autoimmune vasculo-occlusive disease, may pose a diagnostic challenge and result in a devastating ocular and systemic outcome. Our study identifies a new retinal finding and evaluates disease outcome. We aimed to assess clinical and imaging findings, systemic manifestations and disease outcome in patients with ocular Susac's syndrome under immunosuppressive/immunomodulation therapies.

METHODS

Retrospective tertiary center study including patients with a diagnosis of Susac's syndrome with >12 months follow up. Medical record review including ocular, neurological and auditory clinical and imaging findings, and treatment modalities. Main outcome measures were clinical manifestations and disease outcome.

RESULTS

Seven patients (14 eyes) with a mean age of 34.1 years were included. Mean follow-up was 31.9 months (12.4-72.4). All had bilateral ocular disease. Retinal microaneurysms, a new ocular finding, were demonstrated in 5 patients and persisted at the final visit. In 5 eyes, they further extended during follow-up. All were treated with immunosuppressive drugs and 5/7 additional immunomodulation therapy. At last examination, best corrected visual acuity was >20/40 in all eyes, 1/10 eyes had visual field deterioration, no eye had active ocular disease, all patients achieved neurological stability, and 1 patient had auditory deterioration.

CONCLUSION

Retinal microaneurysms, a new ocular finding in Susac's syndrome, were present in most of our patients, indicating ischemic retinal damage. Immunosuppressive and immunomodulation therapies seem to be highly effective in the control of disease activity.

Diagnosis, differential diagnosis and misdiagnosis of Susac syndrome

Background and purpose

Susac syndrome (SuS) is an inflammatory condition of the brain, eye and ear. Diagnosis can be challenging, and misdiagnosis is common.

Methods

This is a retrospective review of the medical records of 32 adult patients from an Australasian cohort of SuS patients.

Results

An alternative diagnosis prior to SuS was made in 30 patients (94%) with seven patients receiving two or more diagnoses. The median time to diagnosis of SuS was 3 months (range 0.5–100 months). The commonest misdiagnoses were migraine in 10 patients (31%), cerebral vasculitis in six (19%), multiple sclerosis in five (16%) and stroke in five (16%). Twenty‐two patients were treated for alternative diagnoses, 10 of whom had further clinical manifestations prior to SuS diagnosis. At presentation seven patients (22%) met criteria for definite SuS, 19 (59%) for probable SuS and six (19%) for possible SuS. Six patients (19%) presented with brain–eye–ear involvement, 14 with brain–ear (44%), six with brain–eye (19%) and six (19%) with only brain involvement. In patients with the complete triad of symptoms the median delay to diagnosis was 3 months (range 1–9 months) compared to 5.25 months (range 0.5–100 months) for patients with encephalopathy and ocular symptoms at presentation.

Conclusions

Susac syndrome patients are frequently misdiagnosed at initial presentation, despite many having symptoms or radiological features that are red flags for the diagnosis. Delayed diagnosis can lead to patient morbidity. The varied ways in which SuS can present, and clinician failure to consider or recognize SuS, appear to be the main factors leading to misdiagnosis.

Role and Relevance of Cerebrospinal Fluid Cells in Diagnostics and Research: State-of-the-Art and Underutilized Opportunities

Cerebrospinal fluid (CSF) has recently experienced a revival in diagnostics and research. However, little progress has been made regarding CSF cell analysis. For almost a century, CSF cell count and cytomorphological examination have been central diagnostic parameters, with CSF pleocytosis as a hallmark finding of neuroinflammation and cytology offering valuable clues regarding infectious, autoimmune, and malignant aetiologies. A great deal of information, however, remains unattended as modern immune phenotyping technologies have not yet been broadly incorporated into routine CSF analysis. This is a serious deficit considering the central role of CSF cells as effectors in central nervous system (CNS) immune defence and autoimmune CNS processes, and the diagnostic challenges posed by clinically overlapping infectious and immune-mediated CNS diseases. Here, we summarize historical, specimen-intrinsic, methodological, and technical issues determining the state-of-the-art diagnostics of CSF cells and outline future perspectives for this underutilized window into meningeal and CNS immunity.

Efficacy and safety of fingolimod in stroke: A systemic review and meta-analysis

BACKGROUND

Brain tissue injury in stroke patients involves inflammation around the infarction lesion or hematoma, which is an important reason for disease deterioration and can result in a poor prognosis. The meta-analysis of animal experiments has concluded that fingolimod could treat stroke in animal models by effectively reducing lymphocyte infiltration. However, no evidence-based efficacy and safety evaluation of fingolimod in stroke patients is currently available.

AIM

To determine whether fingolimod could promote reduction of infarction lesion or hematoma and improve neurological prognosis in stroke patients.

METHODS

Data extracted for treatment effect included count of T-lymphocytes with cluster of differentiation 8 expression (CD8⁺ T cells, × 10⁶/mL), lesion volume (infarction or hematoma, mL), and modified Barthel indexes. Data extracted for safety was risk ratio (RR). Overall standard mean difference (SMD) with its 95% confidence interval (95%CI) and pooled effect with its 95%CI were calculated with a fixed-effects model. I-square (I²) was used to test the heterogeneity. Funnel plot symmetry and Egger's regression were used to evaluate publication bias.

RESULTS

Four high-quality randomized controlled trials were included. There was a significant difference in CD8⁺ T cell count (I² = 0, overall SMD = -3.59, 95%CI: -4.37-2.80, P = 0.737) and modified Barthel index (I² = 0, overall SMD = 2.42, 95%CI: 1.63-3.21, P = 0.290) between the fingolimod and control groups. However, there was no significant difference in lesion volume (I² = 10.6%, overall SMD = -0.17, 95%CI: -0.75-0.42, P = 0.917), fever (pooled RR = 0.93, 95%CI: 0.97-2.32, P = 0.864), suspected lung infection (pooled RR = 0.90, 95%CI: 0.33-2.43, P = 0.876), or any adverse events occurring at least once (pooled RR = 0.82, 95%CI: 0.36-1.87, P = 0.995) between the fingolimod and control groups. There was no publication bias. All of the results were stable as revealed by sensitivity analysis.

CONCLUSION

Fingolimod improves neurological function in stroke patients without promotion of lesion absorption. Taking fingolimod orally (0.5 mg/d, 3 consecutive days) is safe except for patients with rare severe adverse events.

Crosstalk of Microorganisms and Immune Responses in Autoimmune Neuroinflammation: A Focus on Regulatory T Cells

Regulatory T cells (Tregs) are the major determinant of peripheral immune tolerance. Many Treg subsets have been described, however thymus-derived and peripherally induced Tregs remain the most important subpopulations. In multiple sclerosis, a prototypical autoimmune disorder of the central nervous system, Treg dysfunction is a pathogenic hallmark. In contrast, induction of Treg proliferation and enhancement of their function are central immune evasion mechanisms of infectious pathogens. In accordance, Treg expansion is compartmentalized to tissues with high viral replication and prolonged in chronic infections. In friend retrovirus infection, Treg expansion is mainly based on excessive interleukin-2 production by infected effector T cells. Moreover, pathogens seem also to enhance Treg functions as shown in human immunodeficiency virus infection, where Tregs express higher levels of effector molecules such as cytotoxic T-lymphocyte-associated protein 4, CD39 and cAMP and show increased suppressive capacity. Thus, insights into the molecular mechanisms by which intracellular pathogens alter Treg functions might aid to find new therapeutic approaches to target central nervous system autoimmunity. In this review, we summarize the current knowledge of the role of pathogens for Treg function in the context of autoimmune neuroinflammation. We discuss the mechanistic implications for future therapies and provide an outlook for new research directions.

Inflammatory complications of CGRP monoclonal antibodies: a case series

BACKGROUND

Calcitonin gene-related peptide (CGRP) is expressed throughout the body and is a known mediator of migraine, exerting this biological effect through activation of trigeminovascular, meningeal and associated neuronal pathways located in close proximity to the central nervous system. Monoclonal antibodies (mAb) targeting the CGRP pathway are an effective new preventive treatment for migraine, with a generally favourable adverse event profile. Pre-clinical evidence supports an anti-inflammatory/immunoregulatory role for CGRP in other organ systems, and therefore inhibition of the normal action of this peptide may promote a pro-inflammatory response.

CASES

We present a case series of eight patients with new or significantly worsened inflammatory pathology in close temporal association with the commencement of CGRP mAb therapy.

CONCLUSION

This case series provides novel insights on the potential molecular mechanisms and side-effects of CGRP antagonism in migraine and supports clinical vigilance in patient care going forward.

INVESTIGATING MICROANGIOPATHY USING SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN PATIENTS WITH SUSAC SYNDROME

PURPOSE

To determine whether optical coherence tomography angiography is of diagnostic utility for Susac syndrome (SuS) by quantifying microvascular retinal changes.

METHODS

We enrolled 18 eyes of 9 healthy controls and 18 eyes of 9 patients with chronic SuS (12 had previous branch retinal artery occlusions and 6 were clinically unaffected). Images of the fovea were taken using an optical coherence tomography angiography system. Analysis included vessel density, fractal dimension, vessel diameter, and measurements of the foveal avascular zone (area, eccentricity, acircularity index, and axis ratio) in deep and superficial retinal layers.

RESULTS

Skeleton density and inner ring vessel density were significantly lower in patients with SuS (skeleton density: Susac 0.11 ± 0.01 vs. controls 0.12 ± 0.01, P = 0.027. VD: SuS 0.39 ± 0.04 vs. controls 0.42 ± 0.02, P = 0.041). Eccentricity and axis ratio were significantly higher in patients with SuS (EC: Susac 0.61 ± 0.11, controls 0.51 ± 0.10, P = 0.003; axis ratio: Susac 1.57 ± 0.28, controls 1.39 ± 0.11, P = 0.005). SuS eyes (affected and unaffected) had poorer outcomes of the remaining vascular parameters compared with controls (P > 0.05).

CONCLUSION

Optical coherence tomography angiography identified chronic microvascular changes in the eyes of patients with chronic SuS. Even clinically unaffected SuS eyes showed poorer vascular parameters. Although further research is needed, this noninvasive imaging modality seems to have the potential to serve as a valuable additive diagnostic tool.

Manifestation of Susac syndrome during interferon beta-1a and glatiramer acetate treatment for misdiagnosed multiple sclerosis: a case report

Background

Susac syndrome (SS) is characterized by the triad of encephalopathy, branch retinal artery occlusion, and sensorineural hearing loss. However, the diagnosis of SS remains difficult because the clinical triad rarely occurs at disease onset, and symptom severity varies. SS symptoms often suggest other diseases, in particular multiple sclerosis (MS), which is more common. Misdiagnosing SS as MS may cause serious complications because MS drugs, such as interferon beta-1a, can worsen the course of SS. This case report confirms previous reports that the use of interferon beta-1a in the course of misdiagnosed MS may lead to exacerbation of SS. Moreover, our case report shows that glatiramer acetate may also exacerbate the course of SS. To the best of our knowledge, this is the first reported case of exacerbation of SS by glatiramer acetate.

Case presentation

We present a case report of a patient with a primary diagnosis of MS who developed symptoms of SS during interferon beta-1a treatment for MS; these symptoms were resolved after the discontinuation of the treatment. Upon initiation of glatiramer acetate treatment, the patient developed the full clinical triad of SS. The diagnosis of MS was excluded, and glatiramer acetate therapy was discontinued. The patient’s neurological state improved only after the use of a combination of corticosteroids, intravenous immunoglobulins, and azathioprine.

Conclusions

The coincidence of SS signs and symptoms with treatment for MS, first with interferon beta-1a and then with glatiramer acetate, suggests that these drugs may influence the course of SS. This case report indicates that treatment with glatiramer acetate may modulate or even exacerbate the course of SS.