Lauren Walker

Inflammation and Epilepsy: The Foundations for a New Therapeutic Approach in Epilepsy?

Emerging data from experimental epilepsy models and resected human brain tissue support the proposed involvement of innate immune system activation and consequent inflammation in epilepsy. Key mediators of this process include interleukin-1β, high-mobility group box protein 1 (HMGB1), and Toll-like receptor (TLR) signaling. These recent findings constitute the basis for a novel avenue of drug development in epilepsy, one that is not only distinct from previous approaches but uniquely based on sound neurobiological evidence.

Molecular isoforms of high-mobility group box 1 are mechanistic biomarkers for epilepsy

Approximately 30% of epilepsy patients do not respond to antiepileptic drugs, representing an unmet medical need. There is evidence that neuroinflammation plays a pathogenic role in drug-resistant epilepsy. The high-mobility group box 1 (HMGB1)/TLR4 axis is a key initiator of neuroinflammation following epileptogenic injuries, and its activation contributes to seizure generation in animal models. However, further work is required to understand the role of HMGB1 and its isoforms in epileptogenesis and drug resistance. Using a combination of animal models and sera from clinically well-characterized patients, we have demonstrated that there are dynamic changes in HMGB1 isoforms in the brain and blood of animals undergoing epileptogenesis. The pathologic disulfide HMGB1 isoform progressively increased in blood before epilepsy onset and prospectively identified animals that developed the disease. Consistent with animal data, we observed early expression of disulfide HMGB1 in patients with newly diagnosed epilepsy, and its persistence was associated with subsequent seizures. In contrast with patients with well-controlled epilepsy, patients with chronic, drug-refractory epilepsy persistently expressed the acetylated, disulfide HMGB1 isoforms. Moreover, treatment of animals with antiinflammatory drugs during epileptogenesis prevented both disease progression and blood increase in HMGB1 isoforms. Our data suggest that HMGB1 isoforms are mechanistic biomarkers for epileptogenesis and drug-resistant epilepsy in humans, necessitating evaluation in larger-scale prospective studies.

Personalized medicine approaches in epilepsy

Epilepsy affects 50 million persons worldwide, a third of whom continue to experience debilitating seizures despite optimum anti‐epileptic drug (AED) treatment. Twelve‐month remission from seizures is less likely in female patients, individuals aged 11–36 years and those with neurological insults and shorter time between first seizure and starting treatment. It has been found that the presence of multiple seizures prior to diagnosis is a risk factor for pharmacoresistance and is correlated with epilepsy type as well as intrinsic severity. The key role of neuroinflammation in the pathophysiology of resistant epilepsy is becoming clear. Our work in this area suggests that high‐mobility group box 1 isoforms may be candidate biomarkers for treatment stratification and novel drug targets in epilepsy. Furthermore, transporter polymorphisms contributing to the intrinsic severity of epilepsy are providing robust neurobiological evidence on an emerging theory of drug resistance, which may also provide new insights into disease stratification. Some of the rare genetic epilepsies enable treatment stratification through testing for the causal mutation, for example SCN1A mutations in patients with Dravets syndrome. Up to 50% of patients develop adverse reactions to AEDs which in turn affects tolerability and compliance. Immune‐mediated hypersensitivity reactions to AED therapy, such as toxic epidermal necrolysis, are the most serious adverse reactions and have been associated with polymorphisms in the human leucocyte antigen (HLA) complex. Pharmacogenetic screening for HLA‐B*15:02 in Asian populations can prevent carbamazepine‐induced Stevens–Johnson syndrome. We have identified HLA‐A*31:01 as a potential risk marker for all phenotypes of carbamazepine‐induced hypersensitivity with applicability in European and other populations. In this review, we explore the currently available key stratification approaches to address the therapeutic challenges in epilepsy.

WONOEP appraisal: Molecular and cellular biomarkers for epilepsy.

Peripheral biomarkers have myriad potential uses for treatment, prediction, prognostication, and pharmacovigilance in epilepsy. To date, no single peripheral biomarker has demonstrated proven effectiveness, although multiple candidates are in development. In this review, we discuss the major areas of focus including inflammation, blood–brain barrier dysfunction, redox alterations, metabolism, hormones and growth factors.

Spontaneous Hemothorax Following Anticoagulation with Low-Molecular-Weight Heparin

Objective: To report a case of spontaneous hemothorax following anticoagulation with low-molecular-weight heparin (LMWH) for the management of suspected pulmonary embolism. Case Summary: A 66-year-old man with a background history of breast carcinoma was admitted with pleuritic chest pain. He was initially managed as a suspected case of pulmonary embolism. Dalteparin, an LMWH, was started at a maximum dose of 18,000 units subcutaneously once daily, according to British national prescribing guidelines. On day 4, following 3 doses of dalteparin, the patient developed acute respiratory distress attributable to a massive right hemothorax confirmed by computed tomography pulmonary angiography (CTPA) and intercostal drainage of 1500 mL of frank blood. CTPA identified no pulmonary embolus or vascular abnormalities. Reaccumulation of hemothorax occurred over the 48 hours following drain removal, necessitating insertion of a second drain, which removed 1400 mL of blood-stained fluid. The patients hemoglobin decreased from 12.7 to 8.5 g/dL and he received a 3-unit blood transfusion. Histologic assessment of pleural fluid revealed no malignancy and results of video-assisted thoracoscopic surgery were normal. Discontinuation of dalteparin on day 4 led to resolution of symptoms. Discussion: The causal association between anticoagulant therapy and spontaneous hemothorax remains relatively uncommon. The striking temporal relationship between commencing dalteparin on day 1 and subsequent development of effusion on day 4, following 3 doses of LMWH, led us to believe that the bleed occurred as a result of the therapy. Exclusion of other causes strengthened this conclusion. Application of the Naranjo probability scale categorized this adverse reaction as being probably due to LMWH. Conclusions: Spontaneous hemothorax is a rare phenomenon in conjunction with LMWH but should be considered in cases of acute respiratory distress following commencement of LMWH.

High mobility group box 1 in the inflammatory pathogenesis of epilepsy: profiling circulating levels after experimental and clinical seizures

Abstract Background High mobility group box 1 (HMGB1) is a chromatin binding protein that is passively released by necrotic cells and actively secreted in response to inflammatory stimuli in a hyperacetylated form. HMGB1 is upregulated in the brain after injury and can regulate localised inflammatory reactions resulting in seizures. Antiepileptic drugs prevent seizures but have no disease modifying effect or influence on natural history. Immunomodulatory antiepileptic drugs have huge potential, but can have serious adverse effects. Patient stratification is required to maximise the benefit to risk ratio. We investigated serum and brain concentrations of HMGB1 in rodent models of seizures and epilepsy and in people with refractory epilepsy. Methods We used three experimental models in this study. Adult male C57BL/6J mice received repeated intraperitoneal injections of kainic acid (KA) until the onset of convulsive status epilepticus; status epilepticus was terminated after 2 h with diazepam, with brain and blood samples obtained at 3, 6, 24, and 72 h and 7 and 14 days thereafter. Tonic seizures were induced in adult male CF1 mice by maximal electroshock (MES) delivered via corneal electrodes, with brain and blood samples obtained at 1, 4, 8, 16, and 24 h after seizure induction. Finally, serial samples were obtained at baseline, 1, 4, 8, and 12 h after an observed seizure from people with drug refractory epilepsy undergoing videoelectroencephalograph telemetry. Total HMGB1 expression was measured by western blot and immunohistochemistry in brain and by ELISA in serum. Expression of individual HMGB1 isoforms was determined by liquid-chromatography tandem mass-spectrometry (LC-MS/MS). Findings HMGB1 expression was significantly raised in hippocampus and cortex (p vs 3 h 16·5 [1·5], p vs 4 h 19·7 [11·3], p vs 4 h 15·2 [7·0], p vs 0·7 [0·3], p vs 1·25 [0·71], p Interpretation These findings suggest that blood and brain HMGB1 concentrations are increased as a result of seizures in both animal models and patients with epilepsy. Increases in HMGB1 might occur as a consequence of seizures. Patients with refractory epilepsy have higher baseline HMGB1, which might predispose them to recurrent seizure activity. The association between HMGB1 and seizures requires further exploration. Funding UK Medical Research Council, ICON, GlaxoSmithKline, AstraZeneca, the Medical Evaluation Unit.

Prospective clinical trials to investigate clinical and molecular biomarkers

Among clinical studies, randomized studies as well as well‐designed observational studies are providing the highest quality data. In addition, these studies represent a good opportunity to examine biomarkers of ictogenesis and epileptogenesis. To date, no validated molecular or cellular biomarker exists for any aspect of epilepsy. We provide an overview of the inflammatory biomarkers under investigation in prospective clinical studies in epilepsy: proinflammatory cytokines in prolonged febrile seizure; High Mobility Group Box 1 (HMGB1) as a prognosis biomarker in epilepsy and the interaction between inflammation and metabolism, in particular, iron metabolism, in epilepsy. The designs of the European Union EPISTOP project following prospectively patients with tuberous sclerosis from birth to the start of the epilepsy and of the Standard and New Antiepileptic Drugs‐II study illustrate how such studies can be used to find new inflammatory biomarkers of ictogenesis and epileptogenesis. If we want to bridge the current gap between having numerous biomarker candidates from preclinical studies and their selective use in clinical practice, we need to explore multiple biologic systems, not just including inflammation. In addition, it is crucial that those involved in the design and support of relevant clinical studies recognize this gap and act accordingly, and in the interests of improving the diagnosis and prognosis for epilepsy.

TEMPORARY REMOVAL: Reference intervals for putative biomarkers of drug-induced liver injury and liver regeneration in healthy human volunteers

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A comparison of HMGB1 concentrations between cerebrospinal fluid and blood in patients with neurological disease

Abstract Aims: To determine whether a correlation exists between paired cerebrospinal fluid (CSF) and serum levels of a novel inflammatory biomarker, high-mobility group box 1 (HMGB1), in different neurological conditions. Methods: HMGB1 was measured in the serum and CSF of 46 neurological patients (18 idiopathic intracranial hypertension [IIH], 18 neurological infection/inflammation [NII] and 10 Rasmussen’s encephalitis [RE]). Results: Mean serum (± SD) HMGB1 levels were 1.43 ± 0.54, 25.28 ± 27.9 and 1.89 ± 1.49 ng/ml for the patients with IIH, NII and RE, respectively. Corresponding mean (± SD) CSF levels were 0.35 ± 0.22, 4.48 ± 6.56 and 2.24 ± 2.35 ng/ml. Both CSF and serum HMGB1 was elevated in NII. Elevated CSF HMGB1 was demonstrated in RE. There was no direct correlation between CSF and serum levels of HMGB1. Conclusion: Serum HMGB1 cannot be used as a surrogate measure for CSF levels. CSF HMGB1 was elevated in NII and RE, its role as a prognostic/stratification biomarker needs further study.

Chapter 20 – Adverse Drug Reactions

Adverse drug reactions (ADRs) are a major problem in clinical practice and drug development. Estimates suggest that they represent 6.5–6.7% of acute hospital admissions. ADRs represent the most common reason for drug withdrawal and the failure of new drugs to reach the market. They are commonly classified as type A (augmented) or type B (bizarre). Type A ADRs are predictable from the known pharmacology of the drug, and research has focused on genetic variation in drug metabolism pathways, such as cytochrome P450 enzymes, to explain the variation in ADR susceptibility. Success with this approach has been highlighted by the tailoring of azathioprine dosages according to thiopurine S-methyltransferase status. Type B ADRs are not predictable from the known pharmacology of the drug and include hypersensitivity reactions to antiepileptics and statin-induced myopathy. Several strong human leukocyte antigen (HLA) associations have been reported for type B ADRs, and testing for human leukocyte antigen B*57:01 is now routine prior to abacavir therapy. This chapter reviews the reported genetic associations with ADRs and explains their significance in clinical practice and the barriers to their clinical implementation.