Peripheral blood expression levels of inflammasome complex components in two different focal epilepsy syndromes

Seizures in brain tumors: pathogenesis, risk factors and management (Review)

Seizures in the context of brain tumors are a relatively common symptom, with higher occurrence rates observed in glioneuronal tumors and gliomas. It is a serious burden that can have a significant impact on the quality of life (QoL) of patients and influence the disease's prognosis. Brain tumor‑related epilepsy (BTRE) is a challenging entity because the pathophysiological mechanisms are not fully understood yet. Nonetheless, neuroinflammation is considered to play a pivotal role. Next to neuroinflammation, findings on the pathogenesis of BTRE have established that certain genetic mutations are involved, of which the most known would be IDH mutations in gliomas. Others discussed more thoroughly in the present review include genes such as PTEN, TP53, IGSF3, and these findings all provide fresh and fascinating insights into the pathogenesis of BTRE. Treatment for BTRE presents unique challenges, mainly related to burdens of polytherapy, debated necessity of anti‑epileptic prophylaxis, and overall impact on the QoL. In fact, there are no established anti‑seizure medications (ASMs) of choice for BTRE, nor is there any protocol to guide the use of these medications at every step of disease progression. Treatment strategies aimed at the tumor, that is surgical procedures, radio‑ and chemotherapy appear to influence seizure control. Conversely, some ASMs have also shown antitumor properties. The present review summarizes and retrospectively analyzes the literature on the pathogenesis and management of BTRE to provide an updated comprehensive understanding. Furthermore, the challenges and opportunities for developing future therapies aimed at BTRE are discussed.

Neutrophil-to-Lymphocyte Ratio as a Potential Predictive Marker for Epileptic Seizures: Unveiling the "V"-Shaped Link

Objective: The neutrophil-to-lymphocyte ratio (NLR) is an important marker of inflammation. An increased NLR has been detected in the blood of patients with epilepsy. However, the correlation between varying NLRs and epileptic seizures (ESs) is still unclear. Methods: A retrospective analysis was conducted, and patients were divided into two groups based on whether they had ES upon admission. Comprehensive data were collected, including routine blood tests, demographic information, and medical histories. The NLR was calculated by dividing the percentage of neutrophils by the percentage of lymphocytes. Results: In total, 414 patients were included (284 males, 151 females; aged 18-90 years), with 271 in the experimental group and 143 in the control group. No significant differences in the NLR were found between the groups (p=0.164). Nonetheless, when NLRs were categorized, a "V"-shaped link with ES was observed. An NLR of 2-3 correlated with the lowest seizure incidence. Higher NLRs were associated with increased neutrophil and decreased lymphocyte counts. Patients with an NLR < 2 had the lowest infection rates and the highest cerebrovascular disease exposure, whereas those with an NLR > 3 had the highest infection rates and were the oldest. Conclusions: NLR modifications can serve as potential predictive markers for ES. However, the relationship between the NLR and ES is not linear. The factors contributing to these variations are multiple and complex. An NLR of 2-3 may represent an equilibrium point. An elevated NLR indicates pronounced inflammatory responses, while a low NLR can have more complex causes.

Potential inflammatory mechanisms of the ketogenic diet against febrile infection-related epilepsy syndrome

Febrile infection-related epilepsy syndrome (FIRES) is a rare epilepsy syndrome with unclear pathogenesis, characterized by fever-induced, super-refractory status epilepticus and high mortality. Studies have shown that ketogenic diet (KD) is effective in controlling convulsions in FIRES, but its mechanisms are unclear. This paper intends to summarize the mechanisms by which KD may exert effects against FIRES. Clinical studies have shown that patients with FIRES have elevated levels of various inflammatory factors such as interleukin (IL)-6, IL-8, IL-10, and so on. KD may exert anti-FIRES effects through several potential inflammatory pathways, including nuclear factor -κB (NF-κB) and NLR family pyrin domain containing 3 (NLRP3). Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) network suggested that KD may play an anti-inflammatory role through several pathways such as cellular senescence and neutrophil extracellular trap formation. These mechanisms need to be further investigated.

Role of inflammasomes and neuroinflammation in epilepsy

Epilepsy is a brain disorder characterized by recurrent seizures, which are brief episodes of abnormal electrical activity in the brain and involuntary movement that can lead to physical injury and loss of consciousness. Seizures are canonically accompanied by increased inflammatory cytokine production that promotes neuroinflammation, brain pathology, and seizure propagation. Understanding the source of pro-inflammatory cytokines which promote seizure pathogenesis could be a gateway to precision epilepsy drug design. This review discusses the inflammasome in epilepsy including its role in seizure propagation and negative impacts on brain health. The inflammasome is a multiprotein complex that coordinates IL-1β and IL-18 production in response to tissue damage, cellular stress, and infection. Clinical evidence for inflammasome signaling in epileptogenesis is reviewed followed by a discussion of emerging strategies to modulate inflammasome activity in epilepsy.

NLRP1 inflammasome in neurodegenerative disorders: From pathology to therapies

Neuroinflammation is a critical component in neurodegenerative disorders. The inflammasome, facilitates the cleavage of caspase-1, leading to the maturation and subsequent secretion of inflammatory factors interleukin (IL)-1β and IL-18. Consequently, pyroptosis mediated by gasdermin D, exacerbates neuroinflammation. Among the inflammasomes, NLRP1/3 are predominant in the central nervous system (CNS), Although NLRP1 was the earliest discovered inflammasome, the specific involvement of NLRP1 in neurodegenerative diseases remains to be fully elucidated. Recently, the discovery of an endogenous inhibitor of NLRP1, dipeptidyl peptidase 9, suggests the feasibility of producing of small-molecule drugs targeting NLRP1. This review describes the latest findings on the role of the NLRP1 inflammasome in the pathology of neurodegenerative disorders, including Alzheimer's disease, and summarises the regulatory mechanisms of NLRP1 inflammasome activation in the CNS. Furthermore, we highlight the recent progress in developing small-molecule and biological inhibitors that modulate the NLRP1 infammasome for the treatment of neurodegenerative disorders, some of which are advancing to preclinical testing. SIGNIFICANCE STATEMENT: The objective of this review is to synthesise the research on the structure, activation, and regulatory mechanisms of the NLRP1 inflammasome, along with its potential impact on both acute and chronic neurodegenerative conditions. The discovery of endogenous inhibitors, such as dipeptidyl peptidase 9 and thioredoxin, and their interaction with NLRP1 suggest the possibility of developing NLRP1-targeted small-molecule drugs for the treatment of neurodegenerative disorders. This review also discusses the use of both direct and indirect NLRP1 inhibitors as prospective therapeutic strategies for these conditions.

Ulinastatin modulates NLRP3 inflammasome pathway in PTZ-induced epileptic mice: A potential mechanistic insight

Objective

The NLRP3 (NOD-like receptor family, pyrin domain containing 3) inflammasome-driven immune-inflammatory response has been shown to play a critical role in epilepsy progression across multiple studies. While Ulinastatin (UTI), an immunomodulatory agent known to target the NLRP3 pathway in neurological disorders, its implications in epilepsy have not been extensively studied. This investigation aims to explore UTI's role and underlying mechanisms in epilepsy.

Methods

To assess UTI's effects on epilepsy severity, neuroinflammation, and BBB integrity, a pentylenetetrazole (PTZ)-induced epilepsy model in mice and a co-culture system involving BV2 and HT22 cells stimulated by lipopolysaccharide (LPS) and ATP were employed. Techniques utilized included qPCR, Western blotting, ELISA, immunohistochemistry (IHC) staining, Evans Blue dye extravasation, glutamate assays, the Morris water maze, and Annexin V apoptosis assays.

Results

In the PTZ model, UTI administration led to a substantial decrease in seizure intensity and susceptibility, inhibited NLRP3 inflammasome activation, reduced neuroinflammatory interactions, lowered hippocampal and systemic inflammatory mediator levels, and improved cognitive performance. Furthermore, UTI upregulated claudin-5 expression, a tight junction protein in the endothelium, and diminished Evans Blue dye leakage, indicating improved BBB integrity. In BV2 and HT22 cell co-culture models, UTI exerted neuroprotective effects by mitigating microglia-mediated neurotoxicity and fostering neuronal recovery.

Conclusions

The findings demonstrate that UTI exerts transformative regulatory effects on the NLRP3 inflammasome in epilepsy models. This intervention effectively suppresses neuroinflammation, lessens seizure severity and susceptibility, and ameliorates epilepsy-related BBB dysfunction and cognitive impairments.

Unveiling the hidden connection: the blood-brain barrier's role in epilepsy

Epilepsy is characterized by abnormal synchronous electrical activity of neurons in the brain. The blood-brain barrier, which is mainly composed of endothelial cells, pericytes, astrocytes and other cell types and is formed by connections between a variety of cells, is the key physiological structure connecting the blood and brain tissue and is critical for maintaining the microenvironment in the brain. Physiologically, the blood-brain barrier controls the microenvironment in the brain mainly by regulating the passage of various substances. Disruption of the blood-brain barrier and increased leakage of specific substances, which ultimately leading to weakened cell junctions and abnormal regulation of ion concentrations, have been observed during the development and progression of epilepsy in both clinical studies and animal models. In addition, disruption of the blood-brain barrier increases drug resistance through interference with drug trafficking mechanisms. The changes in the blood-brain barrier in epilepsy mainly affect molecular pathways associated with angiogenesis, inflammation, and oxidative stress. Further research on biomarkers is a promising direction for the development of new therapeutic strategies.

Inflammasomes at the crossroads of traumatic brain injury and post-traumatic epilepsy

Post-traumatic epilepsy (PTE) is one of the most debilitating consequences of traumatic brain injury (TBI) and is one of the most drug-resistant forms of epilepsy. Novel therapeutic treatment options are an urgent unmet clinical need. The current focus in healthcare has been shifting to disease prevention, rather than treatment, though, not much progress has been made due to a limited understanding of the disease pathogenesis. Neuroinflammation has been implicated in the pathophysiology of traumatic brain injury and may impact neurological sequelae following TBI including functional behavior and post-traumatic epilepsy development. Inflammasome signaling is one of the major components of the neuroinflammatory response, which is increasingly being explored for its contribution to the epileptogenic mechanisms and a novel therapeutic target against epilepsy. This review discusses the role of inflammasomes as a possible connecting link between TBI and PTE with a particular focus on clinical and preclinical evidence of therapeutic inflammasome targeting and its downstream effector molecules for their contribution to epileptogenesis. Finally, we also discuss emerging evidence indicating the potential of evaluating inflammasome proteins in biofluids and the brain by non-invasive neuroimaging, as potential biomarkers for predicting PTE development.

Peripheral blood regulatory B and T cells are decreased in patients with focal epilepsy

Patients with focal epilepsy of unknown cause (FEoUC) may display T cell infiltration in post-surgery brain specimens and increased serum levels of pro-inflammatory cytokines produced by B and T cells, indicating potential involvement of adaptive immunity. Our study aimed to investigate the peripheral blood distribution of B and T cell subgroups to find clues supporting the distinct organization of adaptive immunity in FEoUC. Twenty-two patients with FEoUC and 25 age and sex matched healthy individuals were included. Peripheral blood mononuclear cells were immunophenotyped by flow cytometry. Expression levels of anti-inflammatory cytokines and FOXP3 were measured by real-time PCR. Carboxyfluorescein succinimidyl ester (CFSE) proliferation assay was conducted using CD4+ T cells. Patients with FEoUC showed significantly decreased regulatory B (Breg), B1a, plasmablast and regulatory T (Treg) cell percentages, and increased switched memory B and Th17 cell ratios. Moreover, CD4+CD25+CD49d- Tregs of FEoUC patients displayed significantly reduced TGFB1 and FOXP3, but increased IL10 gene expression levels. CD4+ helper T cells of patients with FEoUC gave more exaggerated proliferation responses to phytohemagglutinin, anti-CD3 and anti-CD28 stimulation. Patients with FEoUC display increased effector lymphocyte, decreased regulatory lymphocyte ratios, and impaired Treg function and enhanced lymphocyte proliferation capacity. Overall, this pro-inflammatory phenotype lends support to the involvement of adaptive immunity in FEoUC.

Inflammasomes in neurological disorders - mechanisms and therapeutic potential

Inflammasomes are molecular scaffolds that are activated by damage-associated and pathogen-associated molecular patterns and form a key element of innate immune responses. Consequently, the involvement of inflammasomes in several diseases that are characterized by inflammatory processes, such as multiple sclerosis, is widely appreciated. However, many other neurological conditions, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, stroke, epilepsy, traumatic brain injury, sepsis-associated encephalopathy and neurological sequelae of COVID-19, all involve persistent inflammation in the brain, and increasing evidence suggests that inflammasome activation contributes to disease progression in these conditions. Understanding the biology and mechanisms of inflammasome activation is, therefore, crucial for the development of inflammasome-targeted therapies for neurological conditions. In this Review, we present the current evidence for and understanding of inflammasome activation in neurological diseases and discuss current and potential interventional strategies that target inflammasome activation to mitigate its pathological consequences.

Increased production of inflammatory cytokines by circulating monocytes in mesial temporal lobe epilepsy: A possible role in drug resistance

We analyzed peripheral blood mononuclear cells (PBMCs) and serum inflammatory biomarkers in patients with mesial temporal lobe epilepsy (drug-resistant - DR, vs. drug-sensitive - DS). Patients with epilepsy showed higher levels of serum CCL2, CCL3, IL-8 and AOPP, and lower levels of FRAP and thiols compared to healthy controls (HC). Although none of the serum biomarkers distinguished DR from DS patients, when analysing intracellular cytokines after in vitro stimulation, DR patients presented higher percentages of IL-1β and IL-6 positive monocytes compared to DS patients and HC. Circulating innate immune cells might be implicated in DR epilepsy and constitute potential new targets for treatments.

The Role of Histone Deacetylases in NLRP3 Inflammasomesmediated Epilepsy

Epilepsy is one of the most common brain disorders that not only causes death worldwide, but also affects the daily lives of patients. Previous studies have revealed that inflammation plays an important role in the pathophysiology of epilepsy. Activation of inflammasomes can promote neuroinflammation by boosting the maturation of caspase-1 and the secretion of various inflammatory effectors, including chemokines, interleukins, and tumor necrosis factors. With the in-depth research on the mechanism of inflammasomes in the development of epilepsy, it has been discovered that NLRP3 inflammasomes may induce epilepsy by mediating neuronal inflammatory injury, neuronal loss and blood-brain barrier dysfunction. Therefore, blocking the activation of the NLRP3 inflammasomes may be a new epilepsy treatment strategy. However, the drugs that specifically block NLRP3 inflammasomes assembly has not been approved for clinical use. In this review, the mechanism of how HDACs, an inflammatory regulator, regulates the activation of NLRP3 inflammasome is summarized. It helps to explore the mechanism of the HDAC inhibitors inhibiting brain inflammatory damage so as to provide a potential therapeutic strategy for controlling the development of epilepsy.

Distribution of peripheral blood mononuclear cell subtypes in patients with West syndrome: Impact of synacthen treatment

BACKGROUND

West Syndrome (WS) is an epileptic encephalopathy that typically occurs in infants and is characterized by hypsarrhythmia, infantile spasms, and neurodevelopmental impairment. Demonstration of autoantibodies and cytokines in some WS patients and favorable response to immunotherapy have implicated inflammation as a putative trigger of epileptiform activity in WS. Our aim was to provide additional support for altered inflammatory responses in WS through peripheral blood immunophenotype analysis.

METHODS

Eight WS cases treated with synacthen and 11 age- and sex-matched healthy volunteers were included. Peripheral blood mononuclear cells (PBMC) were isolated and immunophenotyping was performed in pre-treatment baseline (8 patients) and 3 months post-treatment (6 patients) samples. The analysis included PBMC expressing NFκB transcription and NLRP3 inflammasome factors.

RESULTS

In pre-treatment baseline samples, switched memory B cells (CD19+IgD-CD27+) were significantly reduced, whereas plasma cells (CD19+CD38+CD138+) and cytotoxic T cells (CD3+CD8+) were significantly increased. Regulatory T and B cell ratios were not significantly altered. Synacthen treatment only marginally reduced helper T cell ratios and did not significantly change other T, B, NK and NKT cell and monocyte ratios.

CONCLUSIONS

Our findings lend further support for the involvement of inflammation-related mechanisms in WS. New-onset WS patients are inclined to display increased plasma cells in the peripheral blood. Synacthen treatment does not show a beneficial effect on most effector acquired and innate immunity subsets.

Systemic inflammation as a biomarker of seizure propensity and a target for treatment to reduce seizure propensity

People with diabetes can wear a device that measures blood glucose and delivers just the amount of insulin needed to return the glucose level to within bounds. Currently, people with epilepsy do not have access to an equivalent wearable device that measures a systemic indicator of an impending seizure and delivers a rapidly acting medication or other intervention (e.g., an electrical stimulus) to terminate or prevent a seizure. Given that seizure susceptibility is reliably increased in systemic inflammatory states, we propose a novel closed-loop device where release of a fast-acting therapy is governed by sensors that quantify the magnitude of systemic inflammation. Here, we review the evidence that patients with epilepsy have raised levels of systemic indicators of inflammation than controls, and that some anti-inflammatory drugs have reduced seizure occurrence in animals and humans. We then consider the options of what might be incorporated into a responsive anti-seizure system.

Neuronal nitric oxide synthase/reactive oxygen species pathway is involved in apoptosis and pyroptosis in epilepsy

Dysfunction of neuronal nitric oxide synthase contributes to neurotoxicity, which triggers cell death in various neuropathological diseases, including epilepsy. Studies have shown that inhibition of neuronal nitric oxide synthase activity increases the epilepsy threshold, that is, has an anticonvulsant effect. However, the exact role and potential mechanism of neuronal nitric oxide synthase in seizures are still unclear. In this study, we performed RNA sequencing, functional enrichment analysis, and weighted gene coexpression network analysis of the hippocampus of tremor rats, a rat model of genetic epilepsy. We found damaged hippocampal mitochondria and abnormal succinate dehydrogenase level and Na⁺-K⁺-ATPase activity. In addition, we used a pilocarpine-induced N2a cell model to mimic epileptic injury. After application of neuronal nitric oxide synthase inhibitor 7-nitroindazole, changes in malondialdehyde, lactate dehydrogenase and superoxide dismutase, which are associated with oxidative stress, were reversed, and the increase in reactive oxygen species level was reversed by 7-nitroindazole or reactive oxygen species inhibitor N-acetylcysteine. Application of 7-nitroindazole or N-acetylcysteine downregulated the expression of caspase-3 and cytochrome c and reversed the apoptosis of epileptic cells. Furthermore, 7-nitroindazole or N-acetylcysteine downregulated the abnormally high expression of NLRP3, gasdermin-D, interleukin-1β and interleukin-18. This indicated that 7-nitroindazole and N-acetylcysteine each reversed epileptic cell death. Taken together, our findings suggest that the neuronal nitric oxide synthase/reactive oxygen species pathway is involved in pyroptosis of epileptic cells, and inhibiting neuronal nitric oxide synthase activity or its induced oxidative stress may play a neuroprotective role in epilepsy.

Neuroinflammation and Proinflammatory Cytokines in Epileptogenesis

Increasing evidence corroborates the fundamental role of neuroinflammation in the development of epilepsy. Proinflammatory cytokines (PICs) are crucial contributors to the inflammatory reactions in the brain. It is evidenced that epileptic seizures are associated with elevated levels of PICs, particularly interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), which underscores the impact of neuroinflammation and PICs on hyperexcitability of the brain and epileptogenesis. Since the pathophysiology of epilepsy is unknown, determining the possible roles of PICs in epileptogenesis could facilitate unraveling the pathophysiology of epilepsy. About one-third of epileptic patients are drug-resistant, and existing treatments only resolve symptoms and do not inhibit epileptogenesis; thus, treatment of epilepsy is still challenging. Accordingly, understanding the function of PICs in epilepsy could provide us with promising targets for the treatment of epilepsy, especially drug-resistant type. In this review, we outline the role of neuroinflammation and its primary mediators, including IL-1β, IL-1α, IL-6, IL-17, IL-18, TNF-α, and interferon-γ (IFN-γ) in the pathophysiology of epilepsy. Furthermore, we discuss the potential therapeutic targeting of PICs and cytokine receptors in the treatment of epilepsy.

Advances regarding Neuroinflammation Biomarkers with Noninvasive Techniques in Epilepsy

A rapidly growing body of evidence supports that neuroinflammation plays a major role in epileptogenesis and disease progression. The capacity to identify pathological neuroinflammation in individuals with epilepsy is a crucial step on the timing of anti-inflammatory intervention and patient selection, which will be challenging aspects in future clinical studies. The discovery of noninvasive biomarkers that are accessible in the blood or molecular neuroimaging would facilitate clinical translation of experimental findings into humans. These innovative and noninvasive approaches have the advantage of monitoring the dynamic changes of neuroinflammation in epilepsy. Here, we will review the available evidence for the measurement of neuroinflammation in patients with epilepsy using noninvasive techniques and critically analyze the major scientific challenges of noninvasive methods. Finally, we propose the potential for use in clinical applications.

Circulating P2X7 Receptor Signaling Components as Diagnostic Biomarkers for Temporal Lobe Epilepsy

Circulating molecules have potential as biomarkers to support the diagnosis of epilepsy and to assist with differential diagnosis, for example, in conditions resembling epilepsy, such as in psychogenic non-epileptic seizures (PNES). The P2X7 receptor (P2X7R) is an important regulator of inflammation and mounting evidence supports its activation in the brain during epilepsy. Whether the P2X7R or P2X7R-dependent signaling molecules can be used as biomarkers of epilepsy has not been reported. P2X7R levels were analyzed by quantitative ELISA using plasma samples from controls and patients with temporal lobe epilepsy (TLE) or PNES. Moreover, blood cell P2X7R expression and P2X7R-dependent cytokine signature was measured following status epilepticus in P2X7R-EGFP reporter, wildtype, and P2X7R-knockout mice. P2X7R plasma levels were higher in TLE patients when compared with controls and patients with PNES. Plasma levels of the broad inflammatory marker protein C-Reactive protein (CRP) were similar between the three groups. Using P2X7R-EGFP reporter mice, we identified monocytes as the main blood cell type expressing P2X7R after experimentally evoked seizures. Finally, cytokine array analysis in P2X7R-deficient mice identified KC/GRO as a potential P2X7R-dependent plasma biomarker following status epilepticus and during epilepsy. Our data suggest that P2X7R signaling components may be a promising subclass of circulating biomarkers to support the diagnosis of epilepsy.

A literature overview on epilepsy and inflammasome activation

Epilepsy is one of the most prevalent serious brain disorders worldwide. Accumulating evidence has suggested that inflammation participates in the progression and pathogenesis of epilepsy. During inflammation, a cytosolic multimolecular complex called the "inflammasome" is activated, driving the innate immune response. This inflammatory pathway by sensing various pathogens and molecules from damaged cells and then activation of caspase-1 enzyme initiates inflammatory responses. Activated caspase-1 leads to the proteolytic cleavage of the pro-inflammatory cytokines, interleukin-1β (IL-1β) and interleukin-18 (IL-18), and also induction of an inflammatory programmed cell death termed pyroptosis. NLR family pyrin domain-containing 1 (NLRP1) and NLRP3 are the two best-characterized inflammasome members, and both basic and clinical research has reported their activation during epilepsy. This overview is intended to summarize the current literature concerning NLRP1 and NLRP3 inflammasome activation and epilepsy.

The role of inflammatory mediators in epilepsy: Focus on developmental and epileptic encephalopathies and therapeutic implications

In recent years, there has been an increasing interest in the potential involvement of neuroinflammation in the pathogenesis of epilepsy. Specifically, the role of innate immunity (that includes cytokines and chemokines) has been extensively investigated either in animal models of epilepsy and in clinical settings. Developmental and epileptic encephalopathies (DEE) are a heterogeneous group of epileptic disorders, in which uncontrolled epileptic activity results in cognitive, motor and behavioral impairment. By definition, epilepsy in DEE is poorly controlled by common antiepileptic drugs but may respond to alternative treatments, including steroids and immunomodulatory drugs. In this review, we will focus on how cytokines and chemokines play a role in the pathogenesis of DEE and why expanding our knowledge about the role of neuroinflammation in DEE may be crucial to develop new and effective targeted therapeutic strategies to prevent seizure recurrence and developmental regression.

Comparison of multiplex cytokine assays in a pediatric cohort with epilepsy

Background

Multiplex analyses allow for detection of dozens of cytokines/chemokines in small sample volumes. Although several commercially available assay kits are available, there are no comparative data in plasma measurements among pediatric or epilepsy cohorts.

New method

Cohort study of 38 children with epilepsy. We evaluated plasma levels of cytokines/chemokines using three different assays: Luminex® xMAP high-sensitivity (HS) and standard-sensitivity (SS) assays, and Meso-Scale Discovery (MSD). We calculated recovery rates of each analyte, correlation coefficients between assays, and level of agreement between measurements. We repeated analyses in a subset of samples after a single freeze-thaw cycle.

Results

Among ten analytes common to all assays, HS had high recovery (<15% of values extrapolated or out-of- range [OOR]) for all analytes, SS for 50%, and MSD for 40%. While several analytes had a high correlation between assays, Bland-Altman plots demonstrated assays were not interchangeable. For most analytes, a single freeze-thaw cycle decreased cytokines/chemokine measurements. There was good correlation of measurements after a freeze-thaw cycle with acceptable agreement between measurements for six of 13 (46%) analytes using HS, one of 9 (11%) for SS, and none for MSD.

Comparison with existing methods

HS assays may optimize yield in plasma for proteins of particular interest in epilepsy research, limit values extrapolated beyond the standard curve, and improve precision compared to other SS and MSD assays.

Conclusion

Our results demonstrate assay choice may be critical to study results and support the need for a standardized approach to biomarker assessment across epilepsy research and other domains.