Fueling the FIRES: Hemophagocytic lymphohistiocytosis in febrile infection-related epilepsy syndrome

Severe, Refractory Seizures: New-Onset Refractory Status Epilepticus and Febrile Infection-Related Epilepsy Syndrome

NORSE (new-onset refractory status epilepticus) and FIRES (febrile infection-related epilepsy syndrome) represent presentations of new-onset status epilepticus without apparent underlying structural, metabolic, or toxic etiology. The cause of NORSE/FIRES remains cryptogenic in up to half of cases, and an abnormal response of the innate immune system has been implicated. Consensus guidelines recommend broad diagnostic investigation and empiric treatment with immunotherapy. NORSE/FIRES is associated with poor outcomes including cognitive impairment and epilepsy, but early recognition and treatment may be important for improving outcomes.

Potential significance of high-mobility group protein box 1 in cerebrospinal fluid

High-mobility group protein box 1 (HMGB1) is a cytokine with multiple functions (according to its subcellular location) that serves a marker of inflammation. CSF HMGB1 could be the part of pathological mechanisms that underlie the complications associated with CNS diseases. HMGB1 actively or passively released into the CSF is detected in the CSF in many diseases of the central nervous system (CNS) and thus may be useful as a biomarker. Pathological alterations in distant areas were observed due to lesions in a specific region, and the level of HMGB1 in the CSF was found to be elevated. Reducing the HMGB1 level via intraventricular injection of anti-HMGB1 neutralizing antibodies can improve the outcomes of CNS diseases. The results indicated that CSF HMGB1 could serve as a biomarker for predicting disease progression and may also act as a pathogenic factor contributing to pathological alterations in distant areas following focal lesions in the CNS. In this mini-review, the characteristics of HMGB1 and progress in research on CSF HMGB1 as a biomarker of CNS diseases were discussed. CSF HMGB1 is useful not only as a biomarker of CNS diseases but may also be involved in interactions between different brain regions and the spinal cord.

Mechanisms and Emerging Therapies for Treatment of Seizures in Pediatric Autoimmune Encephalitis and Autoinflammatory/Autoimmune-Associated Epilepsy

There has been increasing understanding of the role of inflammation in seizures and epilepsy, as well as targeted immunomodulatory treatments. In children, immune-mediated seizures often present acutely in the setting of autoimmune encephalitis and are very responsive to immunotherapy with low rates of subsequent epilepsy. Conversely, seizures in autoimmune-associated epilepsies, such as Rasmussen syndrome, can remain refractory to multimodal therapy, including immunomodulation. In this review, the authors discuss the presentations of immune-mediated seizures in children, underlying mechanisms, and emerging therapies.

Secondary hemophagocytic lymphohistiocytosis in children (Review)

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening condition characterized by hyperinflammation in an uncontrolled and ineffective immune response. Despite great improvement in diagnosis and treatment, it still represents a challenge in clinical management, with poor prognosis in the absence of an aggressive therapeutic approach. The present literature review focuses on secondary HLH at pediatric age, which represents a heterogeneous group in terms of etiology and therapeutic approach. It summarizes the most recent evidence on epidemiology, pathophysiology, diagnosis, treatment and prognosis, and provides a detailed description and comparison of the major subtypes of secondary HLH. Finally, it addresses the open questions with a focus on diagnosis and new treatment insights.

Drug-resistant seizures associated with hyperinflammatory monocytes in FIRES

OBJECTIVE

Therapeutic strategies for patients with febrile infection-related epilepsy syndrome (FIRES) are limited, ad hoc, and frequently ineffective. Based on evidence that inflammation drives pathogenesis in FIRES, we used ex vivo stimulation of peripheral blood mononuclear cells (PBMCs) to characterize the monocytic response profile before and after therapy in a child successfully treated with dexamethasone delivered intrathecally six times between hospital Day 23 and 40 at 0.25 mg/kg/dose.

METHODS

PBMCs were isolated from serial blood draws acquired during refractory status epilepticus (RSE) and following resolution associated with intrathecal dexamethasone therapy in a previously healthy 9-year-old male that presented with seizures following Streptococcal pharyngitis. Cells were stimulated with bacterial or viral ligands and cytokine release was measured and compared to responses in age-matched healthy control PBMCs. Levels of inflammatory factors in the blood and CSF were also measured and compared to pediatric healthy control ranges.

RESULTS

During RSE, serum levels of IL6, CXCL8, HMGB1, S100A8/A9, and CRP were significantly elevated. IL6 was elevated in CSF. Ex vivo stimulation of PBMCs collected during RSE revealed hyperinflammatory release of IL6 and CXCL8 in response to bacterial stimulation. Following intrathecal dexamethasone, RSE resolved, inflammatory levels normalized in serum and CSF, and the PBMC hyperinflammatory response renormalized.

SIGNIFICANCE

FIRES may be associated with a hyperinflammatory monocytic response to normally banal bacterial pathogens. This hyperinflammatory response may induce a profound neutrophil burden and the consequent release of factors that further exacerbate inflammation and drive neuroinflammation. Intrathecal dexamethasone may resolve RSE by resetting this inflammatory feedback loop.

Inflammatory epilepsy (FIRES) and haemophagocytic lymphohistiocytosis (HLH): an adult case

We describe a man in his 30s with haemophagocytic lymphohistiocytosis (HLH), secondary to an upper respiratory tract infection, with subsequent febrile infection-related epilepsy syndrome. He had a prolonged hospital admission, during which he was treated with chemotherapy for HLH and antiepileptic medications for refractory seizures. He was discharged fully dependent to a care facility and died from aspiration pneumonia 11 months later. This case report highlights his management and discusses these conditions' pathophysiology and future management.

Seizure burden and neuropsychological outcomes of new-onset refractory status epilepticus: Systematic review

Background

Long-term sequelae of the new onset refractory status epilepticus (NORSE) include the development of epilepsy, cognitive deficits, and behavioral disturbances. The prevalence of these complications has been previously highlighted in case reports and case series: however, their full scope has not been comprehensively assessed.

Methods

We conducted a systematic review of the literature (PROSPERO ID CRD42022361142) regarding neurological and functional outcomes of NORSE at 30 days or longer following discharge from the hospital. A systematic review protocol was developed using guidance from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

Results

Of the 1,602 records for unique publications, 33 reports on adults and 52 reports on children met our inclusion criteria. They contained the description of 280 adults and 587 children of whom only 75.7 and 85% of patients, respectively had data on long-term follow-up. The mean age of adult and pediatric patients was 34.3 and 7.9 years, respectively; and the longest duration of follow up were 11 and 20 years, respectively. Seizure outcomes received major attention and were highlighted for 93.4 and 96.6% of the adult and pediatric NORSE patients, respectively. Seizures remained medically refractory in 41.1% of adults and 57.7% of children, while seizure freedom was achieved in only 26 and 23.3% of these patients, respectively. The long-term cognitive outcome data was provided for just 10.4% of the adult patients. In contrast, cognitive health data were supplied for 68.9% of the described children of whom 31.9% were moderately or severely disabled. Long-term functional outcomes assessed with various standardized scales were reported in 62.2 and 25.5% of the adults and children, respectively with majority of patients not being able to return to a pre-morbid level of functioning. New onset psychiatric disorders were reported in 3.3% of adults and 11.2% of children recovering from NORSE.

Conclusion

These findings concur with previous observations that the majority of adult and pediatric patients continue to experience recurrent seizures and suffer from refractory epilepsy. Moderate to severe cognitive disability, loss of functional independence, and psychiatric disorders represent a hallmark of chronic NORSE signifying the major public health importance of this disorder.

Functional outcomes of patients with NORSE and FIRES treated with immunotherapy: A systematic review

OBJECTIVE

To determine the frequency of good functional outcomes in patients with NORSE and FIRES treated with immunotherapy.

METHODS

We performed a systematic search of the MedLine and EMBASE databases to gather studies including at least 5 patients with NORSE or FIRES and at least one patient treated with immunotherapy, and reporting functional outcomes. Good functional outcome was defined as a modified Rankin Scale (mRS) score ≤ 2 (or an equivalent measure) at the last available follow-up assessment. Only patients with known functional outcomes were included in the analysis.

RESULTS

We analyzed 16 studies including a total of 161 patients with NORSE. Six studies were carried out only with FIRES patients (n = 64). Of the 161 patients with NORSE, 141 (87.5%) received immunotherapy. Outcome data were available for 135, 56 of whom (41.4%) achieved good functional outcomes. Twenty-four of the 58 patients with FIRES treated with immunotherapy and for whom outcome data were available achieved good functional outcomes (41.3%). Mortality rates in patients with NORSE and FIRES treated with immunotherapy were 20/121 (16.5%) and 6/58 (10.3%), respectively. By type of immunotherapy, good functional outcomes were achieved in 36/89 patients receiving glucocorticoids (40.4%), 27/71 patients receiving IV immunoglobulins (38%), 11/37 patients treated with plasma exchange (29.7%), 5/17 patients receiving rituximab (29.4%), and 2/13 patients receiving cyclophosphamide (15.3%).

CONCLUSION

Despite the lack of randomised clinical trials, immunotherapy is frequently prescribed to patients with NORSE and FIRES. However, rates of functional dependence and mortality remain high in these patients. Second-line therapies achieved lower rates of good outcomes, probably because they were administered to patients with more severe, refractory disease.

International consensus recommendations for management of New Onset Refractory Status Epilepticus (NORSE) incl. Febrile Infection-Related Epilepsy Syndrome (FIRES): Statements and Supporting Evidence

OBJECTIVE

To develop consensus-based recommendations for the management of adult and paediatric patients with NORSE/FIRES based on best evidence and experience.

METHODS

The Delphi methodology was followed. A facilitator group of 9 experts was established, who defined the scope, users and suggestions for recommendations. Following a review of the current literature, recommendation statements concerning diagnosis, treatment and research directions were generated which were then voted on a scale of 1 (strongly disagree) to 9 (strongly agree) by a panel of 48 experts in the field. Consensus that a statement was appropriate was reached if the median score was greater or equal to 7, and inappropriate if the median score was less than or equal to 3. The analysis of evidence was mapped to the results of each statement included in the Delphi survey.

RESULTS

Overall, 85 recommendation statements achieved consensus. The recommendations are divided into five sections: 1) disease characteristics, 2) diagnostic testing and sampling, 3) acute treatment, 4) treatment in the post-acute phase, and 5) research, registries and future directions in NORSE/FIRES. The detailed results and discussion of all 85 statements are outlined herein. A corresponding summary of findings and practical flowsheets are presented in a companion article.

SIGNIFICANCE

This detailed analysis offers insight into the supporting evidence and the current gaps in the literature that are associated with expert consensus statements related to NORSE/FIRES. The recommendations generated by this consensus can be used as a guide for the diagnosis, evaluation, and management of patients with NORSE/FIRES, and for planning of future research.

Inflammation in pediatric epilepsies: Update on clinical features and treatment options

The role of inflammation is increasingly recognized in triggering or sustaining epileptic activity. In the last decades, increasing research has provided definite evidence to support the link between immunity, inflammatory process, and epilepsy. Neuro- and systemic inflammation play a pivotal role in driving epileptogenesis through different pathogenetic mechanisms: the activation of innate immunity in glia, neurons, and microvasculature, the brain mediated by blood-brain barrier (BBB) impairment, and the imbalance of pro- and anti-inflammatory molecules produced by both arms of immunity. More recently, research has focused on the adverse effects of maternal or early-life immune activation and cytokine imbalance on fetal neurodevelopment and postnatal epilepsy. A complex crosstalk between the immune and nervous system, and a crucial interplay of genetic, epigenetic, and environmental factors may influence structures and functions of the developing brain. A better understanding of the inflammatory process in promoting epilepsy implies that targeting specific pathways may be effective in seizure control. Multiple targets have been identified so far, and several antiseizure interventions are obtained by inhibiting inflammatory signaling or protecting/restoring BBB. All this evidence has changed the field of epilepsy research and neuropharmacology. Further developments and new treatments will rapidly emerge to improve seizure management in inflammation-related epilepsies. This article is part of the Special Issue "Severe Infantile Epilepsies".

Molecular Mechanisms in the Genesis of Seizures and Epilepsy Associated With Viral Infection

Seizures are a common presenting symptom during viral infections of the central nervous system (CNS) and can occur during the initial phase of infection ("early" or acute symptomatic seizures), after recovery ("late" or spontaneous seizures, indicating the development of acquired epilepsy), or both. The development of acute and delayed seizures may have shared as well as unique pathogenic mechanisms and prognostic implications. Based on an extensive review of the literature, we present an overview of viruses that are associated with early and late seizures in humans. We then describe potential pathophysiologic mechanisms underlying ictogenesis and epileptogenesis, including routes of neuroinvasion, viral control and clearance, systemic inflammation, alterations of the blood-brain barrier, neuroinflammation, and inflammation-induced molecular reorganization of synapses and neural circuits. We provide clinical and animal model findings to highlight commonalities and differences in these processes across various neurotropic or neuropathogenic viruses, including herpesviruses, SARS-CoV-2, flaviviruses, and picornaviruses. In addition, we extensively review the literature regarding Theiler's murine encephalomyelitis virus (TMEV). This picornavirus, although not pathogenic for humans, is possibly the best-characterized model for understanding the molecular mechanisms that drive seizures, epilepsy, and hippocampal damage during viral infection. An enhanced understanding of these mechanisms derived from the TMEV model may lead to novel therapeutic interventions that interfere with ictogenesis and epileptogenesis, even within non-infectious contexts.

Unraveling the enigma of new-onset refractory status epilepticus: a systematic review of aetiologies

BACKGROUND AND PURPOSE

New-onset refractory status epilepticus (NORSE) is a clinical presentation, neither a specific diagnosis nor a clinical entity. It refers to a patient without active epilepsy or other pre-existing relevant neurological disorder, with a NORSE without a clear acute or active structural, toxic or metabolic cause. This study reviews the currently available evidence about the aetiology of patients presenting with NORSE and NORSE-related conditions.

METHODS

A systematic search was carried out for clinical trials, observational studies, case series and case reports including patients who presented with NORSE, febrile-infection-related epilepsy syndrome or the infantile hemiconvulsion-hemiplegia and epilepsy syndrome.

RESULTS

Four hundred and fifty records were initially identified, of which 197 were included in the review. The selected studies were retrospective case-control (n = 11), case series (n = 83) and case reports (n = 103) and overall described 1334 patients both of paediatric and adult age. Aetiology remains unexplained in about half of the cases, representing the so-called 'cryptogenic NORSE'. Amongst adult patients without cryptogenic NORSE, the most often identified cause is autoimmune encephalitis, either non-paraneoplastic or paraneoplastic. Infections are the prevalent aetiology of paediatric non-cryptogenic NORSE. Genetic and congenital disorders can have a causative role in NORSE, and toxic, vascular and degenerative conditions have also been described.

CONCLUSIONS

Far from being a unitary condition, NORSE is a heterogeneous and clinically challenging presentation. The development and dissemination of protocols and guidelines to standardize diagnostic work-up and guide therapeutic approaches should be implemented. Global cooperation and multicentre research represent priorities to improve the understanding of NORSE.

Hemophagocytic Lymphohistiocytosis

CONTEXT.—

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder of immune regulation that can eventually result in end-organ damage and death. HLH is characterized by uncontrolled activation of cytotoxic T lymphocytes, natural killer cells, and macrophages that can lead to a cytokine storm. The diagnosis of HLH is often challenging due to the diverse clinical manifestations and the presence of several diagnostic mimics. The prognosis is generally poor, warranting rapid diagnosis and aggressive management.

OBJECTIVE.—

To provide a comprehensive review of the pathogenesis, clinical features, diagnosis, and management of HLH.

DATA SOURCES.—

Peer-reviewed literature.

CONCLUSIONS.—

HLH is a condition where a complete understanding of the pathogenesis, early diagnosis, and proper management has an important role in determining patient outcome. Genetic mutations causing impairment in the function of cytotoxic T lymphocytes and natural killer cells have been identified as the root cause of familial HLH; however, the specific pathogenesis of acquired HLH is unclear. The HLH-2004 protocol used in the diagnosis of HLH was originally developed for the pediatric population. The HLH-2004 protocol still forms the basis of the diagnosis of HLH in adults, although its use in adults has not been formally validated yet. Treatment of HLH is primarily based on the HLH-94 protocol, which involves suppressing the inflammatory response, but the treatment needs to be modified in adults depending on the underlying cause and comorbidities.

Dramatic Course of Paediatric Cryptogenic Febrile Infection-Related Epilepsy Syndrome with Unusual Chronic Phase Presentation-A Case Report with Literature Study

Febrile Infection-Related Epilepsy Syndrome (FIRES) is a catastrophic, extremely rare epileptic encephalopathy. It strikes previously healthy school-aged children and is usually cryptogenic. Its dramatic onset with refractory status epilepticus is always preceded by a nonspecific febrile illness. The seizure activity in FIRES may last for several weeks with little to no response to antiepileptic treatment, usually resulting in the usage of anaesthetics. This acute phase is followed by a chronic, refractory epilepsy and cognitive deficit, that persist for the rest of the patient’s life. Still to this day no definite cause has been described. In this study we review the current finding in FIRES and describe a case of a 4-year-old patient with a dramatic course of the acute phase in FIRES and unusual presentation of the chronic phase, which is dominated by extrapyramidal symptoms such as dystonia. This case highlights that the clinical presentation of FIRES may differ from those frequently described in literature.

Chanwuyi Lifestyle Medicine Program Alleviates Immunological Deviation and Improves Behaviors in Autism

Given the association between deviated inflammatory chemokines, the pathogenesis of autism spectrum disorders (ASD), and our previous findings of the Chanwuyi Lifestyle Medicine Program regarding improved cognitive and behavioral problems in ASD, the present study aims to explore if this intervention can alter pro-inflammatory chemokines concentration. Thirty-two boys with ASD were assigned to the experimental group receiving the Chanwuyi Lifestyle Medicine Program for 7 months or the control group without a change in their lifestyle. The experimental group, but not the control group, demonstrated significantly reduced CCL2 and CXCL8, a trend of reduction in CCL5, and elevation of CXCL9. The experimental group also demonstrated significantly reduced social communication problems, repetitive/stereotypic behaviors, and hyperactive behaviors. The present findings support the potential efficacy and applicability of the Chanwuyi Lifestyle Medicine Program for reducing both behavioral problems and immunological dysfunction in ASD. Further studies are warranted to verify its treatment effect and its association with brain functions.

Brain dysfunction in COVID-19 and CAR-T therapy: cytokine storm-associated encephalopathy

OBJECTIVE

Many neurological manifestations are associated with COVID-19, including a distinct form of encephalopathy related to cytokine storm, the acute systemic inflammatory syndrome present in a subgroup of COVID-19 patients. Cytokine storm is also associated with immune effector cell-associated neurotoxicity syndrome (ICANS), a complication of chimeric antigen receptor T-cell (CAR-T) therapy, a highly effective treatment for refractory hematological malignancies. We investigated whether COVID-19-related encephalopathy, ICANS, and other encephalopathies associated with cytokine storm, share clinical and investigative findings.

METHODS

Narrative literature review.

RESULTS

Comparisons between COVID-19-related encephalopathy and ICANS revealed several overlapping features. Clinically, these included dysexecutive syndrome, language disturbances, akinetic mutism and delirium. EEG showed a prevalence of frontal abnormalities. Brain MRI was often unrevealing. CSF elevated cytokine levels have been reported. A direct correlation between cytokine storm intensity and severity of neurological manifestations has been shown for both conditions. Clinical recovery occurred spontaneously or following immunotherapies in most of the patients. Similar clinical and investigative features were also reported in other encephalopathies associated with cytokine storm, such as hemophagocytic lymphohistiocytosis, sepsis, and febrile infection-associated encephalopathies.

INTERPRETATION

COVID-19-related encephalopathy and ICANS are characterized by a predominant electro-clinical frontal lobe dysfunction and share several features with other encephalopathies associated with cytokine storm, which may represent the common denominator of a clinical spectrum of neurological disorders. Therefore, we propose a unifying definition of cytokine storm-associated encephalopathy (CySE), and its diagnostic criteria.

Super refractory status in a case of Febrile Infection-Related Epilepsy Syndrome due to hemophagocytic lymphocytic histiocytosis

A 14-year-old boy presented with a prodromal respiratory infection followed by super refractory status epilepticus. A diagnosis of Febrile Infection-Related Epilepsy Syndrome (FIRES) was made. Initial MRI study and CSF analysis were normal. He required multiple anticonvulsants owing to the refractory nature of the seizures. The course of the illness was rather stormy, laced with various medical problems viz. hepatic dysfunction, sepsis, hemodynamic, and hematological abnormalities which posed several challenges in the management. Hemophagocytic lymphocytic histiocytosis (HLH) was identified as the etiology of the illness and was treated but without success. The case report highlights the several immunomodulatory strategies that were employed to treat the disease, despite which the outcome was unfavorable.

Anakinra usage in febrile infection related epilepsy syndrome: an international cohort

Febrile-infection related epilepsy syndrome (FIRES) is a devastating neurological condition characterized by a febrile illness preceding new onset refractory status epilepticus (NORSE). Increasing evidence suggests innate immune dysfunction as a potential pathological mechanism. We report an international retrospective cohort of 25 children treated with anakinra, a recombinant interleukin-1 receptor antagonist, as an immunomodulator for FIRES. Anakinra was potentially safe with only one child discontinuing therapy due to infection. Earlier anakinra initiation was associated with shorter duration of mechanical ventilation, ICU and hospital length of stay. Our retrospective data lay the groundwork for prospective consensus-driven cohort studies of anakinra in FIRES.

Life-threatening secondary hemophagocytic lymphohistiocytosis following vagal nerve stimulator infection in a child with CHD2 myoclonic encephalopathy: a case report

Vagus nerve stimulation (VNS) is a surgical treatment available for patients affected by generalized refractory epilepsy. The authors report the case of a 15-year-old girl affected by CHD2-related myoclonic encephalopathy and BLM haploinsufficiency due to a deletion of 15q25.3q26.2 region, who suffered from secondary hemophagocytic lymphohistiocytosis (SHLH) after a VNS wound infection. SHLH has sporadically been described in epileptic patients. Based on indirect evidence that shows immune dysregulation in patients with CHD2 mutations and BLM mutations, we hypothesize that the genetic background of this patient may have played a critical role in the development of the syndrome.

Baicalein Ameliorates Epilepsy Symptoms in a Pilocarpine-Induced Rat Model by Regulation of IGF1R

Treatment for epilepsy, particularly temporal lobe epilepsy, is challenging. Baicalein has multiple effects, including anti-inflammatory action. However, little is known about its efficacy in treatment of epilepsy. In this study, we established a pilocarpine-induced rat model and used it for assessment of baicalein efficacy in vivo. We predicted the pharmacological mechanism of baicalein by network pharmacology and RNA sequencing analyses. Pilocarpine epileptic rats treated with baicalein exhibited improved average seizure severity, seizure frequency, seizure duration, and survival time. Network pharmacology and RNA sequencing identified the differentially expressed genes between the baicalein treatment and epileptic groups. Insulin-like growth factor 1 receptor (IGF1R) was chosen as the top candidate target because of its overlapping findings in RNA sequencing and network pharmacology data. Western blotting, immunofluorescence, and polymerase chain reaction analyses showed that baicalein inhibited microglial proliferation, IGF1R, and inflammatory cytokine expression. Moreover, baicalein improved epilepsy symptoms. Inhibition of IGF1R function by blocking with AXL1717 enhanced baicalein treatment efficacy both in vivo and in vitro. In conclusion, baicalein exerted antiepileptic effects by regulation of IGF1R in a pilocarpine-induced rat model.

Neurocritical care and target immunotherapy for febrile infection-related epilepsy syndrome

Febrile infection-related epilepsy syndrome (FIRES) is an intractable neurological disease characterized by an unexplained refractory status epilepticus triggered by febrile infection. A Consensus definition of FIRES was proposed in 2018, and its clinical features and prognosis are gradually being clarified. However, the development of effective treatments has been hindered as the etiology of this rare disease is as yet unelucidated. The basic approach to the management of FIRES, like other forms of epilepsy, is based on the control of seizures, however seizures are extremely intractable and require intravenous administration of large doses of anticonvulsants, mainly barbiturates. This treatment strategy produces various complications including respiratory depression and drug hypersensitivity syndrome, which make it more difficult to control seizures. Consequently, it is crucial to predict these events and to formulate a planned treatment strategy. As well, it is important to grow out of conventional treatment strategies that rely on only anticonvulsants, and alternative therapies are gradually being developed. One such example is the adoption of a ketogenic diet which may lead to reduced convulsions as well as improve intellectual prognosis. Further, overproduction of inflammatory cytokines in the central nervous system has been shown to be strongly related to the pathology of FIRES which has led to attempts at immunomodulation therapy including anti-cytokine therapy.

Serum high mobility group box protein 1 (HMGB1) levels reflect clinical features of childhood hemophagocytic lymphohistiocytosis

Purpose

Hemophagocytic lymphohistiocytosis (HLH) is a potentially lethal hyperinflammatory disorder. For further understanding of the pathogenesis of HLH, we examined serum levels of high mobility group box protein 1 (HMGB1) in children with HLH.

Patients and methods

Serum HMGB1 levels were measured in 28 patients with HLH and 6 normal controls using a quantitative enzyme-linked immunosorbent assay. The patients were 21 boys and 7 girls, aged from 10 days to 21 years, with a median age of 8.5 years. The underlying conditions of HLH were infection-associated HLH in 18 patients, malignancy-associated HLH in 7 patients, and genetic HLH in 3 patients. The relations between serum HMGB1 levels and clinical symptoms and laboratory parameters were analyzed.

Results

Serum HMGB1 levels were significantly higher in patients with HLH than in normal controls (median, 6.5 ng/mL, interquartile range, 4.25–13.1). The serial serum HMGB1 levels in one patient fell to reflect the disease activity. Serum HMGB1 levels were significantly higher in patients with disseminated intravascular coagulation (DIC) than in patients without DIC (p<0.001) and were also significantly higher in patients with central nervous system (CNS) complications than in patients without CNS complications (p<0.01). Serum HMGB1 levels were positively correlated with aspartate aminotransferase (r_s =0.48, p<0.01, Spearman’s rank correlation coefficient) and negatively correlated with fibrinogen (r_s = −0.475, p=0.011) and hemoglobin (r_s = −0.465, p=0.013).

Conclusion

Serum HMGB1 levels reflect clinical features of childhood HLH. HMGB1 is a potential mediator involved in the pathogenesis and determining the clinical findings of HLH.

Challenges in the diagnosis of hemophagocytic lymphohistiocytosis: Recommendations from the North American Consortium for Histiocytosis (NACHO)

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of pathologic immune activation, often associated with genetic defects of lymphocyte cytotoxicity. Though a distinctive constellation of features has been described for HLH, diagnosis remains challenging as patients have diverse presentations associated with a variety of triggers. We propose two concepts to clarify how HLH is diagnosed and treated: within the broader syndrome of HLH, "HLH disease" should be distinguished from "HLH disease mimics" and HLH subtypes should be categorized by specific etiologic associations, not the ambiguous dichotomy of "primary" and "secondary." We provide expert-based advice regarding the diagnosis and initiation of treatment for patients with HLH, rooted in improved understanding of its pathophysiology.

Hemophagocytic Lymphohistiocytosis: Prevalence, Risk Factors, Outcome, and Outcome-related Factors in Adult Idiopathic Inflammatory Myopathies

OBJECTIVE

To clarify the prevalence, risk factors, outcome, and outcome-related factors of hemophagocytic lymphohistiocytosis (HLH) in patients with dermatomyositis (DM), polymyositis (PM), or clinically amyopathic dermatomyositis (CADM).

METHODS

Data of patients with DM, PM, or CADM who were admitted to the First Affiliated Hospital of Zhejiang University from February 2011 to February 2019 were retrospectively collected. Patients diagnosed with HLH constituted the case group. A 1:4 case-control study was performed to identify risk factors for HLH in patients with DM, PM, or CADM through comparison, univariate, and multivariate logistic regression analysis. Intragroup comparison was made among patients with HLH to identify factors influencing unfavorable short-term outcome.

RESULTS

HLH was a rare (4.2%) but fatal (77.8%) complication in patients with DM, PM, or CADM. The retrospective case-control study revealed that higher on-admission disease activity (p = 0.008), acute exacerbation of interstitial lung disease (AE-ILD, p = 0.002), and infection (p = 0.002) were risk factors for complication of HLH in patients with DM, PM, or CADM. The following intragroup comparison showed that higher on-admission disease activity (p = 0.035) and diagnosis of CADM (p = 0.039) might influence the short-term outcome of patients with HLH. However, no risk factor was identified after false discovery rate correction.

CONCLUSION

In this study, secondary HLH was a fatal complication, with higher on-admission disease activity, AE-ILD, and infection working as risk factors. The underlying role of infection and autoimmune abnormality in HLH in connective tissue disease was subsequently noted. Clinical factors influencing the short-term outcome of patients with secondary HLH require further study.

Functional deficiency in endogenous interleukin-1 receptor antagonist in patients with febrile infection-related epilepsy syndrome

OBJECTIVE

We recently reported successful treatment of a child with febrile infection-related epilepsy syndrome (FIRES), a subtype of new onset refractory status epilepticus, with the recombinant interleukin-1 (IL1) receptor antagonist (IL1RA) anakinra. On this basis, we tested whether endogenous IL1RA production or function is deficient in FIRES patients.

METHODS

Levels of IL1β and IL1RA were measured in serum and cerebrospinal fluid (CSF). The inhibitory activity of endogenous IL1RA was assessed using a cell-based reporter assay. IL1RN gene variants were identified by sequencing. Expression levels for the secreted and intracellular isoforms of IL1RA were measured in patient and control cells by real-time polymerase chain reaction.

RESULTS

Levels of endogenous IL1RA and IL1β were elevated in the serum and CSF of patients with FIRES (n = 7) relative to healthy controls (n = 10). Serum from FIRES patients drove IL1R signaling activity and potentiated IL1R signaling in response to exogenous IL1β in a cell-based reporter assay. Functional assessment of endogenous IL1RA activity in 3 FIRES patients revealed attenuated inhibition of IL1R signaling. Sequencing of IL1RN in our index patient revealed multiple variants. This was accompanied by reduced expression of intracellular but not secreted isoforms of IL1RA in the patient's peripheral blood mononuclear cells.

INTERPRETATION

Our findings suggest that FIRES is associated with reduced expression of intracellular IL1RA isoforms and a functional deficiency in IL1RA inhibitory activity. These observations may provide insight into disease pathogenesis for FIRES and other inflammatory seizure disorders and may provide a valuable biomarker for therapeutic decision-making. Ann Neurol 2019;85:526-537.