In-thrombus thrombin secretion: a new diagnostic marker of atrial fibrillation in cryptogenic stroke.

Endovascularly retrieved clots may be a potential resource for diagnosing stroke etiology. This method may influence secondary prevention treatment. We measure thrombin activity eluted by serially washing clots. We concluded that an assay measuring the change in thrombin in clots retrieved during acute stroke endovascular thrombectomy procedures may serve as a diagnostic marker of the origin of the clot. The suggested mechanism for these differences may be the clot location before its retrieval, with high blood flow causing thrombin washout in atherosclerotic clots, in contrast to atrium appendage low blood flow retaining high thrombin levels.

Autoantibodies to Annexin A2 and cerebral thrombosis: Insights from a mouse model.

INTRODUCTION: Antiphospholipid syndrome (APS) is an autoimmune disorder manifested by thromboembolic events, recurrent spontaneous abortions and elevated titers of circulating antiphospholipid antibodies. In addition, the presence of antiphospholipid antibodies seems to confer a fivefold higher risk for stroke or transient ischemic attack. Although the major antigen of APS is ß2 glycoprotein I, it is now well established that antiphospholipid antibodies are heterogeneous and bind to various targets. Recently, antibodies to Annexin A2 (ANXA2) have been reported in APS. This is of special interest since data indicated ANXA2 as a key player in fibrinolysis. Therefore, in the present study we assessed whether anti-ANXA2 antibodies play a pathological role in thrombosis associated disease. MATERIALS AND METHODS: Mice were induced to produce anti-ANXA2 antibodies by immunization with ANXA2 (iANXA2) and control mice were immunized with adjuvant only. A middle cerebral artery occlusion stroke model was applied to the mice. The outcome of stroke severity was assessed and compared between the two groups. RESULTS: Our results indicate that antibodies to ANXA2 lead to a more severe stroke as demonstrated by a significant larger stroke infarct volume (iANXA2 133.9 ± 3.3 mm3 and control 113.7 ± 7.4 mm3; p = 0.017) and a more severe neurological outcome (iANXA2 2.2 ± 0.2, and control 1.5 ± 0.18; p = 0.03). CONCLUSIONS: This study supports the hypothesis that auto-antibodies to ANXA2 are an independent risk factor for cerebral thrombosis. Consequently, we propose screening for anti-ANXA2 antibodies should be more widely used and patients that exhibit the manifestations of APS should be closely monitored by physicians.

In-thrombus thrombin secretion: a new diagnostic marker of atrial fibrillation in cryptogenic stroke.

BACKGROUND: Endovascularly retrieved clots are a potential resource for diagnosing stroke etiology, which may influence secondary prevention treatment. In this study we measured thrombin activity eluted by serially washing clots. METHODS: Clots were retrieved from 68 patients with acute ischemic stroke, freshly frozen and classified by standard criteria into proven atrial fibrillation (AF, 18 patients), atherosclerotic origin (AS, 15 patients), cryptogenic stroke (Cr, 17 patients) and other known causes (18 patients). Thawed clot samples were washed by transferring them into 1 mL buffer in seven hourly cycles and a fluorescent substrate assay was used to measure secreted thrombin activity. The clots were also examined histologically. Artificial fibrin and red blood cell-rich clots were similarly assayed for wash-eluted thrombin activity as an external control. RESULTS: Thrombin activity eluted from clots of AF origin decreased significantly with time in contrast to steady levels eluted from AS origin thrombi (P<0.0001 by repeated measures ANOVA). The Cr stroke group was indistinguishable from the AF group and differed statistically from the AS group (P=0.017 by repeated measures ANOVA). In artificial clots we found a biphasic activity pattern, with initially decreasing levels of eluted thrombin (AF pattern) and then, with continuing washes, steady eluted thrombin levels (AS pattern). CONCLUSIONS: An assay measuring the change in thrombin in clots retrieved during acute stroke endovascular thrombectomy procedures may serve as a diagnostic marker of the origin of the clot. The suggested mechanism for these differences may be the clot location before its retrieval, with high blood flow causing thrombin washout in atherosclerotic clots, in contrast to atrium appendage low blood flow retaining high thrombin levels.

Rituximab for refractory manifestations of the antiphospholipid syndrome: a multicentre Israeli experience.

OBJECTIVES: The clinical manifestations of the antiphospholipid syndrome (APS) are heterogeneous and related to anti-phospholipid antibodies (aPL). There is some evidence that B cells are involved in the pathogenesis of this condition. Thus the ability of rituximab (RTX) to deplete B cells makes it an appealing potential therapy for refractory antiphospholipid syndrome (APS). Real world data on RTX treatment of APS are still lacking. This study was conducted to report outcomes of RTX administration in the treatment of different aspects of APS. METHODS: This is a retrospective case series study on APS patients from 3 medical centres in Israel who were treated with RTX during 2010-2019 for refractory manifestations of APS including diffuse alveolar haemorrhage, recurrent thrombosis, cytopenia, neurological and skin manifestations. Medical records were reviewed regarding the clinical indication for RTX treatment, concomitant medications, RTX protocol, aPL status and response to treatment. Outcomes were defined as complete response if full resolution of the "indicated manifestation" was achieved and maintained for at least 12 months, partial response or no response. RESULTS: We identified 40 APS patients who were treated with RTX for refractory manifestations of this condition, of whom, 24 patients (60%) were female with a mean age of 40 years, and 31 patients (78%) were diagnosed with primary APS. A favourable response to RTX was documented in 32 patients (80%) including a complete response in 22 patients (55%). Response to RTX treatment was associated with a rituximab protocol of 375mg/m2 x 4 compared to a fixed dose of 1000 mg x2 (100% vs. 65%; p=0.01). Complete response was associated with a decrease in aPL titres within 4-6 months post treatment, whereas no significant change in aPL titres was observed in patients with partial or no response. CONCLUSIONS: Consistent with previous small case series, we report a good therapeutic response to RTX in patients with difficult to treat manifestations of APS. In this cohort, treatment protocols were associated with outcomes. Although further studies are required to verify our observations, our data support a plausible role for B cell depletion in refractory APS.

Anti-neurofilament antibodies and neurodegeneration: Markers and generators.

Neuroaxonal injury and loss result in the release of cytoskeleton components, including neurofilaments, into the cerebrospinal fluid and peripheral blood. Once released, neurofilaments are highly immunogenic, inducing a specific antibody response. Anti-neurofilament antibody levels correlate with the progression of diverse neurological diseases; however, their role both in the pathogenesis of disease and as a tool for monitoring disease progression is not well understood. This study reviews the current literature on anti-neurofilament antibodies. We suggest the testing of anti-neurofilament antibodies be further developed for diagnosis and targeted for treatment.

Extrapyramidal signs in neurosarcoidosis versus multiple sclerosis: Is TNF alpha the link?

Specific inflammatory pathways and specifically Tumor Necrosis Factor alpha (TNF-α) have been associated with the neurodegeneration in Parkinson's disease (PD). TNFα is also known to play an important role in the pathogenesis of sarcoidosis and TNF blockers can ameliorate the disease. In contrast, multiple sclerosis (MS) is clearly exacerbated by anti- TNF-α medications. We have therefore hypothesized that Parkinson-like disease would be more common in neurosarcoidosis (NS) compared to MS. The aim of this case-control study was therefore to assess the frequency of extrapyramidal signs in patients with NS compared to MS patients. In order to do so the medical records of NS patients and of age and gender matched MS patients were reviewed and data regarding the clinical features, ancillary tests performed, treatment, and outcome were documented. Patients were then examined in a uniform manner for the presence of extrapyramidal signs. We found that in the NS group 8 patients had minor signs, one had mild functional disability and 3 subjects had significant extrapyramidal signs compatible with the diagnosis of Parkinson's disease. All extrapyramidal signs found in 5 of the MS group were minor. The proportional severity of extrapyramidal signs was significantly higher (p=0.045, chi square test) in the NS group compared to the MS group. We conclude that the specificity of extrapyramidal to NS raises the intriguing question of whether specific inflammatory pathways involving TNF-α play a role in the pathogenesis of PD and therefore may be a therapeutic target.

Diagnosis and classification of neuromyelitis optica (Devic's syndrome).

Neuromyelitis optica (NMO) is an autoimmune disorder, predominantly characterized by severe optic neuritis (ON) and transverse myelitis (TM). Historically considered a variant of Multiple sclerosis, the discovery that most NMO patients have autoantibodies against aquaporin-4 (AQP4) or NMO-IgG, dramatically changed our understanding of the disease. The finding of NMO-IgG revealed wider array of clinical presentations, including patients with recurrent ON of TM alone, now considered part of the NMO spectrum. Furthermore, symptoms other than optic-spinal involvement and the presence of brain lesions, do not exclude the diagnosis of NMO as traditionally accepted. We present an overview of the epidemiology, clinical manifestations and current diagnostic criteria for NMO and NMO spectrum disorders.