Characteristic Cytokine and Chemokine Profiles in Encephalitis of Infectious, Immune-Mediated, and Unknown Aetiology

Diagnostic markers of acute encephalitis syndrome and COVID-associated multisystem inflammatory syndrome in children from Southern India

Acute encephalitis syndrome (AES) in children poses a significant public health challenge in India. This study aims to explore the utility of host inflammatory mediators and neurofilament (NfL) levels in distinguishing etiologies, assessing disease severity, and predicting outcomes in AES. We assessed 12 mediators in serum (n = 58) and 11 in cerebrospinal fluid (CSF) (n = 42) from 62 children with AES due to scrub typhus, viral etiologies, and COVID-associated multisystem inflammatory syndrome (MIS-C) in Southern India. Additionally, NfL levels in serum (n = 20) and CSF (n = 18) were examined. Clinical data, including Glasgow coma scale (GCS) and Liverpool outcome scores, were recorded. Examining serum and CSF markers in the three AES etiology groups revealed notable distinctions, with scrub typhus differing significantly from viral and MIS-C causes. Viral causes had elevated serum CCL11 and CCL2 compared with scrub typhus, while MIS-C cases showed higher HGF levels than scrub typhus. However, CSF analysis showed a distinct pattern with the scrub typhus group exhibiting elevated levels of IL-1RA, IL-1β, and TNF compared with MIS-C, and lower CCL2 levels compared with the viral group. Modeling the characteristic features, we identified that age ≥3 years with serum CCL11 < 180 pg/mL effectively distinguished scrub typhus from other AES causes. Elevated serum CCL11, HGF, and IL-6:IL-10 ratio were associated with poor outcomes (p = 0.038, 0.005, 0.02). Positive CSF and serum NfL correlation, and negative GCS and serum NfL correlation were observed. Median NfL levels were higher in children with abnormal admission GCS and poor outcomes. Measuring immune mediators and brain injury markers in AES provides valuable diagnostic insights, with the potential to facilitate rapid diagnosis and prognosis. The correlation between CSF and serum NfL, along with distinctive serum cytokine profiles across various etiologies, indicates the adequacy of blood samples alone for assessment and monitoring. The association of elevated levels of CCL11, HGF, and an increased IL-6:IL-10 ratio with adverse outcomes suggests promising avenues for therapeutic exploration, warranting further investigation.

Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses

To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1-11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely.

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.

Cytokine Patterns as Predictors of Antibiotic Treatment Effect in Chronic Low Back Pain with Modic Changes: Subgroup Analyses of a Randomized Trial (AIM Study)

Objective

Randomized trials testing the effect of antibiotics for chronic low back pain (LBP) with vertebral bone marrow changes on MRI (Modic changes) report inconsistent results. A proposed explanation is subgroups with low grade discitis where antibiotics are effective, but there is currently no method to identify such subgroups. The objective of the present study was to evaluate whether distinct patterns of serum cytokine levels predict any treatment effect of oral amoxicillin at one-year follow-up in patients with chronic low back pain and Modic changes at the level of a previous lumbar disc herniation.

Design

We used data from an overpowered, randomized, placebo-controlled trial (the AIM study) that tested 100 days of oral 750 mg amoxicillin vs placebo three times daily in hospital outpatients with chronic (>6 months) LBP with pain intensity ≥5 on a 0-10 numerical rating scale and Modic changes type 1 (oedema type) or 2 (fatty type). We measured serum levels of 40 inflammatory cytokines at baseline and analysed six predefined potential predictors of treatment effect based on cytokine patterns in 78 randomized patients; three analyses with recursive partitioning, one based on cluster analysis and two based on principal component analyses. The primary outcome was the Roland-Morris Disability Questionnaire score at one-year follow-up in the intention to treat population. The methodology and overall results of the AIM study were published previously.

Results

The 78 patients were 25-62 years old and 47 (60%) were women. None of the three recursive partitioning analyses resulted in any suggested subgroups. Of all main analyses, the largest effect estimate (mean difference between antibiotic and placebo groups) was seen in a subgroup not predefined as of main interest (Cluster category 3+4; -2.0, 95% CI: -5.2-1.3, RMDQ points; p-value for interaction 0.54).

Conclusion

Patterns of inflammatory serum cytokine levels did not predict treatment effect of amoxicillin in patients with chronic LBP and Modic changes.

Clinical Trial Registration Number

ClinicalTrials.gov (identifier: NCT02323412).

Stop Being So Negative: Favorable Outcome and Response to Immune Therapies in Antibody-Negative Probable Autoimmune Encephalitis

Seronegative Autoimmune Encephalitis: Clinical Characteristics and Factors Associated With Outcomes

Lee WJ, Lee HS, Kim DY, Lee HS, Moon J, Park KI, Lee SK, Chu K, Lee ST. Brain. 2022;145(10):3509-3521. doi:10.1093/brain/awac166

Seronegative autoimmune encephalitis is autoimmune encephalitis without any identifiable pathogenic antibody. Although it is a major subtype of autoimmune encephalitis, many unmet clinical needs exist in terms of clinical characteristics, treatments and prognosis. In this institutional cohort study, patients diagnosed with seronegative autoimmune encephalitis with available 2-year outcomes were analysed for the disease course, 2-year outcome prediction system, effect of immunotherapy, necessity of further immunotherapy at 6 or 12 months and pattern of brain atrophy. Seronegative autoimmune encephalitis was subcategorized into antibody-negative probable autoimmune encephalitis, autoimmune limbic encephalitis and acute disseminated encephalomyelitis. Poor 2-year outcome was defined by modified Rankin scale scores 3–6, and the 2-year serial data of Clinical Assessment Scales in Autoimmune Encephalitis score was used for longitudinal data analyses. A total of 147 patients were included. The frequency of achieving a good 2-year outcome (modified Rankin scale 0–2) was 56.5%. The antibody-negative probable autoimmune encephalitis subtype exhibited the poorest outcomes, although the baseline severity was similar among the subtypes. The RAPID score, consisting of five early usable clinical factors, refractory status epilepticus, age of onset ≥60 years, probable autoimmune encephalitis (antibody-negative probable autoimmune encephalitis subtype), infratentorial involvement and delay of immunotherapy ≥1 month, was associated with poorer 2-year outcomes. Any immunotherapy was associated with clinical improvement in the patients with low risk for poor 2-year outcomes (RAPID scores 0–1), and the combination immunotherapy of steroid, immunoglobulin, rituximab and tocilizumab was associated with better outcomes in the patients with high risk for poor 2-year outcomes (RAPID scores 2–5). In patients with persistent disease at 6 months, continuing immunotherapy was associated with more improvement, while the effect of continuing immunotherapy for more than 12 months was unclear. In the longitudinal analysis of MRI, the development of cerebellar atrophy indicated poor outcomes, while the absence of diffuse cerebral atrophy or medial temporal atrophy indicated the possibility of a good outcome. This study provides information about the clinical characteristics and courses, the effect of immunotherapy and its duration, and prognostic factors in seronegative autoimmune encephalitis.

Cytokines and chemokines profile in encephalitis patients: A meta-analysis

BACKGROUND

Encephalitis is caused by autoimmune or infectious agents marked by brain inflammation. Investigations have reported altered concentrations of the cytokines in encephalitis. This study was conducted to determine the relationship between encephalitis and alterations of cytokine levels in cerebrospinal fluid (CSF) and serum.

METHODS

We found possibly suitable studies by searching PubMed, Embase, Scopus, and Web of Science, systematically from inception to August 2021. 23 articles were included in the meta-analysis. To investigate sources of heterogeneity, subgroup analysis and sensitivity analysis were conducted. The protocol of the study has been registered in PROSPERO with a registration ID of CRD42021289298.

RESULTS

A total of 23 met our eligibility criteria to be included in the meta-analysis. A total of 12 cytokines were included in the meta-analysis of CSF concentration. Moreover, 5 cytokines were also included in the serum/plasma concentration meta-analysis. According to the analyses, patients with encephalitis had higher CSF amounts of IL-6, IL-8, IL-10, CXCL10, and TNF-α than healthy controls. The alteration in the concentration of IL-2, IL-4, IL-17, CCL2, CXCL9, CXCL13, and IFN-γ was not significant. In addition, the serum/plasma levels of the TNF-α were increased in encephalitis patients, but serum/plasma concentration of the IL-6, IL-10, CXCL10, and CXCL13 remained unchanged.

CONCLUSIONS

This meta-analysis provides evidence for higher CSF concentrations of IL-6, IL-8, IL-10, CXCL10, and TNF-α in encephalitis patients compared to controls. The diagnostic and prognostic value of these cytokines and chemokines should be investigated in future studies.

Exploring the management approaches of cytokines including viral infection and neuroinflammation for neurological disorders

Considerable evidence supports that cytokines are important mediators of pathophysiologic processes within the central nervous system (CNS). Numerous studies have documented the increased production of various cytokines in the human CNS in various neurological and neuropsychiatric disorders. Deciphering cytokine actions in the intact CNS has important implications for our understanding of the pathogenesis and treatment of these disorders. The purpose of this study is to discuss the recent research on treating cytokine storm and amyloids, including stroke, Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's condition, Multi-sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS). Neuroinflammation observed in neurological disorders has a pivotal role in exacerbating Aβ burden and tau hyperphosphorylation, suggesting that stimulating cytokines in response to an undesirable external response could be a checkpoint for treating neurological disorders. Furthermore, the pro-inflammatory cytokines help our immune system through a neuroprotective mechanism in clearing viral infection by recruiting mononuclear cells. This study reveals that cytokine applications may play a vital role in providing novel regulation and methods for the therapeutic approach to neurological disorders and the causes of the deregulation, which is responsible for neuroinflammation and viral infection. However, it needs to be further investigated to clarify better the mechanisms of cytokine release in response to various stimuli, which could be the central point for treating neurological disorders.

Age-related changes in the inflammatory responses to viral infections in the central nervous system during childhood

BACKGROUND

The developmental stages and function of immune cells in the central nervous system during infancy and childhood are poorly understood. We analyzed whether cytokine and chemokine profiles in children and adolescents with viral central nervous system infections were different depending on age.

METHODS

The acute phase cerebrospinal fluid of 80 children (mean age 98 months, range 1-206 months) were analyzed for protein levels of interleukin-1β (IL-1β), IL-1-RA, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-15, IL-17, IL-18, monocyte chemoattractant protein-1 (MCP-1), interferon (IFN) gamma-induced protein 10 (IP-10), IFN-γ, and macrophage migration inhibitory factor (MIF).

RESULTS

We found an age-dependent increased expression of IL-4, IL-6, IL-13, MIF, IP-10, and IFN-γ and a decreased expression of MCP-1 and IL-15 in response to a viral infection of the central nervous system. In contrast, all other cytokines and chemokine were unaffected by the age of the patient.

CONCLUSION

These findings demonstrate that the immunological response to a viral infection matures during childhood and adolescence. This may in turn be of importance for the outcome of a viral infection and the risk for subsequent sequela. It also demonstrates that age is a factor that needs to be considered when using cytokines and chemokines as biomarkers for infections in the central nervous system.

IMPACT

The immunological response to a viral infection matures during childhood and adolescence. This may be of importance for the outcome of a viral infection and the risk for subsequent sequela. It also demonstrates that age is a factor that needs to be considered when using cytokines and chemokines as biomarkers for infections in the central nervous system.

Protocol for DexEnceph: a randomised controlled trial of dexamethasone therapy in adults with herpes simplex virus encephalitis

INTRODUCTION

Herpes simplex virus (HSV) encephalitis is a rare severe form of brain inflammation that commonly leaves survivors and their families with devastating long-term consequences. The virus particularly targets the temporal lobe of the brain causing debilitating problems in memory, especially verbal memory. It is postulated that immunomodulation with the corticosteroid, dexamethasone, could improve outcomes by reducing brain swelling. However, there are concerns (so far not observed) that such immunosuppression might facilitate increased viral replication with resultant worsening of disease. A previous trail closed early because of slow recruitment.

METHOD

DexEnceph is a pragmatic multicentre, randomised, controlled, open-label, observer-blind trial to determine whether adults with HSV encephalitis who receive dexamethasone alongside standard antiviral treatment with aciclovir for have improved clinical outcomes compared with those who receive standard treatment alone. Overall, 90 patients with HSV encephalitis are being recruited from a target of 45 recruiting sites; patients are randomised 1:1 to the dexamethasone or control arms of the study. The primary outcome measured is verbal memory as assessed by the Weschler Memory Scale fourth edition Auditory Memory Index at 26 weeks after randomisation. Secondary outcomes are measured up to 72 weeks include additional neuropsychological, clinical and functional outcomes as well as comparison of neuroimaging findings. Patient safety monitoring occurs throughout and includes the detection of HSV DNA in cerebrospinal fluid 2 weeks after randomisation, which is indicative of ongoing viral replication. Innovative methods are being used to ensure recrutiment targets are met for this rare disease.

DISCUSSION

DexEnceph aims to be the first completed randomised controlled trial of corticosteroid therapy in HSV encephalitis. The results will provide evidence for future practice in managing adults with the condition and has the potential to improve outcomes .

ETHICS AND DISSEMINATION

The trial has ethical approval from the UK National Research Ethics Committee (Liverpool Central, REF: 15/NW/0545, 10 August 2015). Protocol V.2.1, July 2019. The results will be published and presented as soon as possible on completion.

TRIAL REGISTRATION NUMBERS

ISRCTN11774734, EUDRACT 2015-001609-16.

Cytokines as a marker of central nervous system autoantibody associated epilepsy

OBJECTIVE

Autoantibodies to central nervous system (CNS) antigens are increasingly identified in patients with epilepsy. Alterations in cytokines and chemokines have also been demonstrated in epilepsy, but this has not been explored in subjects with autoantibodies. If antibody positive and antibody negative subjects show a difference in immune activation, as measured by cytokine levels, this could improve diagnostic and therapeutic approaches, and provide insights into the underlying pathophysiology. We aimed to evaluate serum and CSF cytokines and chemokines in patients with and without autoantibody positivity to identify any differences between the two groups.

METHODS

We studied participants who had undergone serum and CSF testing for CNS autoantibodies, as part of their clinical evaluation. Cases were classified as antibody positive or antibody negative for comparison. Stored CSF and sera were analysed for cytokine and chemokine concentrations.

RESULTS

25 participants underwent testing. 8 were antibody positive, 17 were antibody negative. Significant elevations in the mean concentration of IL-13 and RANTES in CSF were found in the antibody positive cases and significant elevation of CSF VEGF was found in the antibody negative cases. Significant elevations in the mean concentrations of serum TNFβ, INFγ, bNGF, IL-8, and IL-12 were seen in the antibody negative group, and there was poor correlation between the majority of serum and CSF concentrations.

SIGNIFICANCE

Measurement of cytokines and chemokines such as IL-13 and RANTES could be useful in diagnosis of autoimmune associated epilepsy. Such markers might also guide targeted immunotherapy to improve seizure control and provide insights into the underlying pathophysiology of epilepsy associated with CNS autoantibodies.

Neurofilament light chain as a biomarker of meningoencephalitis of unknown etiology in dogs

BACKGROUND

Neurofilament light chain (NfL) is a neuron-specific cytoskeletal protein expressed in axons. Damaged axons of the central nervous system release NfLs into the cerebrospinal fluid (CSF) and the blood. In humans with neurologic diseases, NfL is used as a biomarker.

OBJECTIVES

To identify the potential of NfL as a supportive tool for the diagnosis, prognosis, and monitoring of meningoencephalitis of unknown etiology (MUE) in dogs.

ANIMALS

Twenty-six client-owned healthy dogs, 10 normal Beagle dogs, and 38 client-owned MUE dogs.

METHODS

Cohort study. The concentrations of NfL in serum and CSF were measured using single-molecule array technology.

RESULTS

Median NfL concentration was significantly higher in MUE dogs (serum, 125 pg/mL; CSF, 14 700 pg/mL) than in healthy dogs (serum, 11.8 pg/mL, P < .0001; CSF, 1410 pg/mL, P = .0002). The areas under the receiver operating characteristic curves of serum and CSF NfL concentrations were 0.99 and 0.95, respectively. The cut-off values were 41.5 pg/mL (serum) and 4005 pg/mL (CSF) for differentiating between healthy and MUE dogs, with sensitivities of 89.19% and 90%, respectively, and specificities of 96.97% and 100%, respectively. The NfL concentration showed a significant decrease (pretreatment, 122 pg/mL; posttreatment, 36.6 pg/mL; P = .02) in the good treatment-response group and a significant increase (pretreatment, 292.5 pg/mL; posttreatment, 1880 pg/mL, P = .03) in the poor treatment-response group.

CONCLUSIONS AND CLINICAL IMPORTANCE

Neurofilament light chain is a potential biomarker for diagnosing MUE and evaluating response to treatment.

Diagnostic utility of cerebrospinal fluid (CSF) findings in seizures and epilepsy with and without autoimmune-associated disease

Patients with seizures and epilepsy routinely undergo multiple diagnostic tests, which may include cerebrospinal fluid (CSF) analysis. This review aims to outline different CSF parameters and their alterations in seizures or epilepsy. We then discuss the utility of CSF analysis in seizure patients in different clinical settings in depth. Some routine CSF parameters are frequently altered after seizures, but are not specific such as CSF protein and lactate. Pleocytosis and CSF specific oligoclonal bands are rare and should be considered as signs of infectious or immune mediated seizures and epilepsy. Markers of neuronal damage show conflicting results, and are as yet not established in clinical practice. Parameters of neuronal degeneration and more specific immune parameters are less well studied, and are areas of further research. CSF analysis in new-onset seizures or status epilepticus serves well in the differential diagnosis of seizure etiology. Here, considerations should include autoimmune-associated seizures. CSF findings in these disorders are a special focus of this review and are summarized in a comprehensive overview. Until now, CSF analysis has not yielded clinically helpful biomarkers for refractory epilepsy or for assessment of neuronal damage which is a subject of further studies.

Astrocyte- and Neuron-Derived CXCL1 Drives Neutrophil Transmigration and Blood-Brain Barrier Permeability in Viral Encephalitis

Herpes simplex virus (HSV)-1 encephalitis has significant morbidity partly because of an over-exuberant immune response characterized by leukocyte infiltration into the brain and increased blood-brain barrier (BBB) permeability. Determining the role of specific leukocyte subsets and the factors that mediate their recruitment into the brain is critical to developing targeted immune therapies. In a murine model, we find that the chemokines CXCL1 and CCL2 are induced in the brain following HSV-1 infection. Ccr2 (CCL2 receptor)-deficient mice have reduced monocyte recruitment, uncontrolled viral replication, and increased morbidity. Contrastingly, Cxcr2 (CXCL1 receptor)-deficient mice exhibit markedly reduced neutrophil recruitment, BBB permeability, and morbidity, without influencing viral load. CXCL1 is produced by astrocytes in response to HSV-1 and by astrocytes and neurons in response to IL-1α, and it is the critical ligand required for neutrophil transendothelial migration, which correlates with BBB breakdown. Thus, the CXCL1-CXCR2 axis represents an attractive therapeutic target to limit neutrophil-mediated morbidity in HSV-1 encephalitis.

Neuropsychiatric Disorders Due to Limbic Encephalitis: Immunologic Aspect

Limbic encephalitis (LE) is a rare cause of encephalitis presenting as an acute and subacute onset of neuropsychiatric manifestations, particularly with memory deficits and confusion as core features, along with seizure occurrence, movement disorders, or autonomic dysfunctions. LE is caused by neuronal antibodies targeting the cellular surface, synaptic, and intracellular antigens, which alter the synaptic transmission, especially in the limbic area. Immunologic mechanisms involve antibodies, complements, or T-cell-mediated immune responses in different degree according to different autoantibodies. Sensitive cerebrospinal fluid markers of LE are unavailable, and radiographic findings may not reveal a typical mesiotemporal involvement at neurologic presentations; therefore, a high clinical index of suspicions is pivotal, and a neuronal antibody testing is necessary to make early diagnosis. Some patients have concomitant tumors, causing paraneoplastic LE; therefore, tumor survey and treatment are required in addition to immunotherapy. In this study, a review on the molecular and immunologic aspects of LE was conducted to gain awareness of its peculiarity, which we found quite different from our knowledge on traditional psychiatric illness.

Pro-inflammatory dopamine-2 receptor-specific T cells in paediatric movement and psychiatric disorders

Objectives

A dysregulated inflammatory response against the dopamine‐2 receptor (D2R) has been implicated in movement and psychiatric disorders. D2R antibodies were previously reported in a subset of these patients; however, the role of T cells in these disorders remains unknown. Our objective was to identify and characterise pro‐inflammatory D2R‐specific T cells in movement and psychiatric disorders.

Methods

Blood from paediatric patients with movement and psychiatric disorders of suspected autoimmune and neurodevelopmental aetiology (n = 24) and controls (n = 16) was cultured in vitro with a human D2R peptide library, and D2R‐specific T cells were identified by flow cytometric quantification of CD4⁺CD25⁺CD134⁺ T cells. Cytokine secretion was analysed using a cytometric bead array and ELISA. HLA genotypes were examined in D2R‐specific T‐cell‐positive patients. D2R antibody seropositivity was determined using a flow cytometry live cell‐based assay.

Results

Three immunodominant regions of D2R, amino acid (aa)121–131, aa171–181 and aa396–416, specifically activated CD4⁺ T cells in 8/24 patients. Peptides corresponding to these regions were predicted to bind with high affinity to the HLA of the eight positive patients and had also elicited the secretion of pro‐inflammatory cytokines IL‐2, IFN‐ γ, TNF, IL‐6, IL‐17A and IL‐17F. All eight patients were seronegative for D2R antibodies.

Conclusion

Autoreactive D2R‐specific T cells and a pro‐inflammatory Th1 and Th17 cytokine profile characterise a subset of paediatric patients with movement and psychiatric disorders, further underpinning the theory of immune dysregulation in these disorders. These findings offer new perspectives into the neuroinflammatory mechanisms of movement and psychiatric disorders and can influence patient diagnosis and treatment.

Central nervous system complications associated with SARS-CoV-2 infection: integrative concepts of pathophysiology and case reports

Coronavirus disease 2019 (COVID-19) is a highly infectious pandemic caused by a novel coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It frequently presents with unremitting fever, hypoxemic respiratory failure, and systemic complications (e.g., gastrointestinal, renal, cardiac, and hepatic involvement), encephalopathy, and thrombotic events. The respiratory symptoms are similar to those accompanying other genetically related beta-coronaviruses (CoVs) such as severe acute respiratory syndrome CoV (SARS-CoV) and Middle East Respiratory Syndrome CoV (MERS-CoV). Hypoxemic respiratory symptoms can rapidly progress to Acute Respiratory Distress Syndrome (ARDS) and secondary hemophagocytic lymphohistiocytosis, leading to multi-organ system dysfunction syndrome. Severe cases are typically associated with aberrant and excessive inflammatory responses. These include significant systemic upregulation of cytokines, chemokines, and pro-inflammatory mediators, associated with increased acute-phase proteins (APPs) production such as hyperferritinemia and elevated C-reactive protein (CRP), as well as lymphocytopenia. The neurological complications of SARS-CoV-2 infection are high among those with severe and critical illnesses. This review highlights the central nervous system (CNS) complications associated with COVID-19 attributed to primary CNS involvement due to rare direct neuroinvasion and more commonly secondary CNS sequelae due to exuberant systemic innate-mediated hyper-inflammation. It also provides a theoretical integration of clinical and experimental data to elucidate the pathogenesis of these disorders. Specifically, how systemic hyper-inflammation provoked by maladaptive innate immunity may impair neurovascular endothelial function, disrupt BBB, activate CNS innate immune signaling pathways, and induce para-infectious autoimmunity, potentially contributing to the CNS complications associated with SARS-CoV-2 infection. Direct viral infection of the brain parenchyma causing encephalitis, possibly with concurrent neurovascular endotheliitis and CNS renin angiotensin system (RAS) dysregulation, is also reviewed.

CSF levels of myelin basic protein in pediatric patients with ventriculoperitoneal shunt infection

Introduction

Hydrocephalus is a common disorder of the central nervous system (CNS) in the pediatric population. Surgical treatment options involve ventriculoperitoneal shunt (VPS) placement. VPS infection is the most common complication of surgically treated hydrocephalus in pediatric patients [1, 2],which may lead to neuronal damage. Myelin basic protein (MBP) has been proposed as a marker of neuronal injury in a variety of contexts, and MBP levels in the cerebrospinal fluid (CSF) may be used to assess the severity of neuronal damage [1, 3, 4]. Therefore, the aim of this study was to evaluate the CSF level of myelin basic protein (MBP) in a group of pediatric patients with VPS infection.

Material and methods

Thirty CSF samples were collected from pediatric patients with VPS infection. CSF levels of MBP were measured at three time points, marked by contamination detection, obtention of the first sterile CSF culture, and VPS shunt implantation. The collected data were compared with those of the control group composed of children with active congenital hydrocephalus and valid CSF values.

Results

The MBP level in the study group was higher than the corresponding control values in the second and third measurements. The highest MBP level was reached in the study group in the second and third measurements.

Conclusions

The lack of normalization of MBP level in the CSF of children with shunt infection could be connected with ongoing brain damage. It takes longer than the normalization of CSF protein level and pleocytosis. The delay is associated with a prolonged reaction of the immunological system.

Novel Surrogate Markers of CNS Inflammation in CSF in the Diagnosis of Autoimmune Encephalitis

Background: Autoimmune encephalitis (AE) is an important cause of refractory epilepsy, rapidly progressive cognitive decline, and unexplained movement disorders in adults. Whilst there is identification of an increasing number of associated autoantibodies, patients remain with a high clinical probability of autoimmune encephalitis but no associated characterized autoantibody. These patients represent a diagnostic and treatment dilemma. Objective: To evaluate routine and novel diagnostic tests of cerebrospinal fluid (CSF) in patients with a high probability of AE to attempt to identify better biomarkers of neuroinflammation. Methods: Over 18 months (2016-2018), adult patients with a high clinical probability of AE were recruited for a pilot cross-sectional explorative study. We also included viral polymerase-chain-reaction (PCR) positive CSF samples and CSF from neurology patients with "non-inflammatory" (NI) diagnoses for comparison. CSF was examined with standard investigations for encephalitis and novel markers (CSF light chains, and cytokines). Results and Conclusions: Thirty-two AE patients were recruited over 18 months. Twenty-one viral controls, 10 NI controls, and five other autoimmune neurological disease controls (AOND) were also included in the analysis. Our study found that conventional markers: presence of CSF monocytosis, oligoclonal bands, anti-neuronal immunofluorescence, and magnetic resonance imaging (MRI) changes could be suggestive of AE, but these investigations were neither sensitive nor specific. Promising novel makers of autoimmune encephalitis were the CSF cytokines IL-21 and IP10 which may provide better delineation between viral infections and autoimmune encephalitis than conventional markers, potentially leading to more immediate diagnosis and management of these patients.

Understanding and managing acute encephalitis

Encephalitis is an important cause of morbidity, mortality, and permanent neurologic sequelae  globally. Causes are diverse and include viral and non-viral infections of the brain as well as autoimmune processes. In the West, the autoimmune encephalitides are now more common than any single infectious cause, but, in Asia, infectious causes are still more common. In 2006, the World Health Organization coined the term "acute encephalitis syndrome", which simply means acute onset of fever with convulsions or altered consciousness or both. In 2013, the International Encephalitis Consortium set criteria for diagnosis of encephalitis on basis of clinical and laboratory features. The most important infectious cause in the West is herpes simplex virus, but globally Japanese encephalitis (JE) remains the single largest cause. Etiologic diagnosis is difficult because of the large number of agents that can cause encephalitis. Also, the responsible virus may be detectable only in the brain and is either absent or transiently found in blood or cerebrospinal fluid (CSF). Virological diagnosis is complex, expensive, and time-consuming. Different centres could make their own algorithms for investigation in accordance with the local etiologic scenarios. Magnetic resonance imaging (MRI) and electroencephalography are specific for few agents. Clinically, severity may vary widely. A severe case may manifest with fever, convulsions, coma, neurologic deficits, and death. Autoimmune encephalitis (AIE)  includes two major categories: (i) classic paraneoplastic limbic encephalitis (LE) with autoantibodies against intracellular neuronal antigens (Eg: Hu and Ma2) and (ii) new-type AIE with autoantibodies to neuronal surface or synaptic antigens (Eg: anti-N-methyl-D-aspartate receptor). AIE has prominent psychiatric manifestations: psychosis, aggression, mutism, memory loss, euphoria, or fear. Seizures, cognitive decline, coma, and abnormal movements are common. Symptoms may fluctuate rapidly. Treatment is largely supportive. Specific treatment is available for herpesvirus group and non-viral infections. Various forms of immunotherapy are used for AIE.

Inflammatory responses to a pathogenic West Nile virus strain

Background

West Nile virus (WNV) circulates across Australia and was referred to historically as Kunjin virus (WNV_KUN). WNV_KUN has been considered more benign than other WNV strains circulating globally. In 2011, a more virulent form of the virus emerged during an outbreak of equine arboviral disease in Australia.

Methods

To better understand the emergence of this virulent phenotype and the mechanism by which pathogenicity is manifested in its host, cells were infected with either the virulent strain (NSW2012), or less pathogenic historical isolates, and their innate immune responses compared by digital immune gene expression profiling. Two different cell systems were used: a neuroblastoma cell line (SK-N-SH cells) and neuronal cells derived from induced pluripotent stem cells (iPSCs).

Results

Significant innate immune gene induction was observed in both systems. The NSW2012 isolate induced higher gene expression of two genes (IL-8 and CCL2) when compared with cells infected with less pathogenic isolates. Pathway analysis of induced inflammation-associated genes also indicated generally higher activation in infected NSW2012 cells. However, this differential response was not paralleled in the neuronal cultures.

Conclusion

NSW2012 may have unique genetic characteristics which contributed to the outbreak. The data herein is consistent with the possibility that the virulence of NSW2012 is underpinned by increased induction of inflammatory genes.

Synergy of Interleukin (IL)-5 and IL-18 in eosinophil mediated pathogenesis of allergic diseases

Eosinophils are circulating granulocytes that have pleiotropic effects in response to inflammatory signals in the body. In response to allergens or pathogens, exposure eosinophils are recruited in various organs that execute pathological immune responses. IL-5 plays a key role in the differentiation, development, and survival of eosinophils. Eosinophils are involved in a variety of allergic diseases including asthma, dermatitis and various gastrointestinal disorders (EGID). IL-5 signal transduction involves JAK-STAT-p38MAPK-NFκB activation and executes extracellular matrix remodeling, EMT transition and immune responses in allergic diseases. IL-18 is a classical cytokine also involved in immune responses and has a critical role in inflammasome pathway. We recently identified the IL-18 role in the generation, transformation, and maturation of (CD101+CD274+) pathogenic eosinophils. In, addition, several other cytokines like IL-2, IL-4, IL-13, IL-21, and IL-33 also contribute in advancing eosinophils associated immune responses in innate and adaptive immunity. This review discusses with a major focus (1) Eosinophils and its constituents, (2) Role of IL-5 and IL-18 in eosinophils development, transformation, maturation, signal transduction of IL-5 and IL-18, (3) The role of eosinophils in allergic disorders and (4) The role of several other associated cytokines in promoting eosinophils mediated allergic diseases.

Distinct serum and cerebrospinal fluid cytokine and chemokine profiles in autoantibody-associated demyelinating diseases

Background

Demyelinating diseases of the central nervous system associated with autoantibodies against aquaporin-4 and myelin-oligodendrocyte-glycoprotein are mediated by different immunopathological mechanisms compared to multiple sclerosis.

Objective

The purpose of this study was to evaluate serum and cerebrospinal fluid cytokine/chemokine profiles in patients with autoantibodies against aquaporin-4 or autoantibodies against myelin-oligodendrocyte-glycoprotein-associated demyelination compared to multiple sclerosis and autoimmune encephalitis.

Methods

Serum and cerebrospinal fluid cytokine/chemokine levels were analysed using Procartaplex Multiplex Immunoassays. First, we analysed a panel of 32 cytokines/chemokines in a discovery group (nine aquaporin-4-antibody seropositive, nine myelin oligodendrocyte glycoprotein-antibody seropositive, eight encephalitis, 10 multiple sclerosis). Significantly dysregulated cytokines/chemokines were validated in a second cohort (11 aquaporin-4-antibody seropositive, 18 myelin oligodendrocyte glycoprotein-antibody seropositive, 18 encephalitis, 33 multiple sclerosis).

Results

We found 11 significantly altered cytokines/chemokines in cerebrospinal fluid and serum samples in the discovery group (a proliferation-inducing ligand, fractalkine=CX3CL1, growth-regulated oncogene-α, interleukin-1 receptor antagonist, interleukin-6, interleukin-8=CXCL8, interleukin-10, interleukin-21, interferon-ɣ-induced protein-10=CXCL10, monokine induced by interferon-ɣ=CXCL9, macrophage inflammatory protein-1ß=CCL4). Most of these cytokines/chemokines were up-regulated in autoantibodies against aquaporin-4 or autoantibodies against myelin-oligodendrocyte-glycoprotein positive patients compared to multiple sclerosis. We confirmed these results for cerebrospinal fluid interleukin-6 and serum interleukin-8, growth-regulated oncogene-α, a proliferation-inducing ligand and macrophage inflammatory protein-1β in the validation set. Receiver-operating characteristic analysis revealed increased levels of cerebrospinal fluid interleukin-6, serum interleukin-8 and growth-regulated oncogene-α in most patients with autoantibody-associated neurological diseases.

Conclusion

This study suggests that distinctive cerebrospinal fluid and serum cytokine/chemokine profiles are associated with autoantibody-mediated demyelination, but not with multiple sclerosis.

Bacteroides fragilis polysaccharide A induces IL-10 secreting B and T cells that prevent viral encephalitis

The gut commensal Bacteroides fragilis or its capsular polysaccharide A (PSA) can prevent various peripheral and CNS sterile inflammatory disorders. Fatal herpes simplex encephalitis (HSE) results from immune pathology caused by uncontrolled invasion of the brainstem by inflammatory monocytes and neutrophils. Here we assess the immunomodulatory potential of PSA in HSE by infecting PSA or PBS treated 129S6 mice with HSV1, followed by delayed Acyclovir (ACV) treatment as often occurs in the clinical setting. Only PSA-treated mice survived, with dramatically reduced brainstem inflammation and altered cytokine and chemokine profiles. Importantly, PSA binding by B cells is essential for induction of regulatory CD4⁺ and CD8⁺ T cells secreting IL-10 to control innate inflammatory responses, consistent with the lack of PSA mediated protection in Rag^−/−, B cell- and IL-10-deficient mice. Our data reveal the translational potential of PSA as an immunomodulatory symbiosis factor to orchestrate robust protective anti-inflammatory responses during viral infections.

The capsular polysaccharide A (PSA) of Bacteroides fragilis is known to have immunomodulatory capability during sterile inflammatory disorders. Here Ramakrishna and colleagues show that PSA administration in a murine model of herpes simplex encephalitis induces IL-10 producing B and T cell populations that confer protection against lethal challenge and brain pathology.

High neopterin and IP-10 levels in cerebrospinal fluid are associated with neurotoxic tryptophan metabolites in acute central nervous system infections

Background

The host response to intruders in the central nervous system (CNS) may be beneficial but could also be harmful and responsible for neurologic symptoms and sequelae in CNS infections. This immune response induces the activation of the kynurenine pathway (KP) with the production of neuroactive metabolites. Herein, we explored cytokine and KP responses in cerebrospinal fluid (CSF) and serum in patients with encephalitis, aseptic, and bacterial meningitis.

Methods

Cytokines were measured in CSF and serum by multiplex assay in adult patients with encephalitis of infectious, autoimmune or unknown etiology (n = 10), aseptic meningitis (ASM, n = 25), acute bacterial meningitis (ABM, n = 6), and disease control patients with similar symptoms but without pleocytosis in CSF (n = 42). Liquid chromatography-tandem mass spectrometry (LC-MS/ MS) was used to measure KP metabolites in CSF and serum.

Results

A characteristic pattern of increasing cytokine levels and KP metabolites was found in CSF from encephalitis to ASM, with the highest levels in ABM. In ASM and ABM, most inflammatory mediators, including IL-6, IL-8, and IFN-inducible protein-10 (IP-10), showed markedly elevated levels in CSF compared with serum, indicating production within the CNS. In contrast to most mediators, the highest level of IP-10 was found in the ASM group, suggesting a potential role for IP-10 in aseptic/viral meningitis. Neopterin and IP-10 were associated with marked changes in KP metabolites in CSF with increasing kynurenine/tryptophan ratio reflecting indoleamine 2,3-dioxygenase activity. Neopterin, a marker of IFN-γ activity, was associated with an unfavorable balance between neuroprotective and neurotoxic tryptophan metabolites.

Conclusion

We show that parenchymal and meningeal inflammations in CNS share a characteristic cytokine profile with a general immune response in the CSF with limited influence from the systemic circulation. IFN-γ activity, assessed by neopterin and IP-10 levels, may play a role in the activation of the KP pathway in these patients, potentially mediating neurotoxic effects.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1366-3) contains supplementary material, which is available to authorized users.

Potential role of CSF cytokine profiles in discriminating infectious from non-infectious CNS disorders

Current laboratory testing of cerebrospinal fluid (CSF) does not consistently discriminate between different central nervous system (CNS) disease states. Rapidly distinguishing CNS infections from other brain and spinal cord disorders that share a similar clinical presentation is critical. New approaches focusing on aspects of disease biology, such as immune response profiles that can have stimulus-specific attributes, may be helpful. We undertook this preliminary proof-of-concept study using multiplex ELISA to measure CSF cytokine levels in various CNS disorders (infections, autoimmune/demyelinating diseases, lymphomas, and gliomas) to determine the potential utility of cytokine patterns in differentiating CNS infections from other CNS diseases. Both agglomerative hierarchical clustering and mixture discriminant analyses revealed grouping of CNS disease types based on cytokine expression. To further investigate the ability of CSF cytokine levels to distinguish various CNS disease states, non-parametric statistical analysis was performed. Mann-Whitney test analysis demonstrated that CNS infections are characterized by significantly higher CSF lP-10/CXCL10 levels than the pooled non-infectious CNS disorders (p = 0.0001). Within the infection group, elevated levels of MDC/CCL22 distinguished non-viral from viral infections (p = 0.0048). Each disease group of the non-infectious CNS disorders independently showed IP-10/CXCL10 levels that are significantly lower than the infection group [(autoimmune /demyelinating disorders (p = 0.0005), lymphomas (p = 0.0487), gliomas (p = 0.0294), and controls (p = 0.0001)]. Additionally, of the non-infectious diseases, gliomas can be distinguished from lymphomas by higher levels of GRO/CXCL1 (p = 0.0476), IL-7 (p = 0.0119), and IL-8 (p = 0.0460). Gliomas can also be distinguished from autoimmune/demyelinating disorders by higher levels of GRO/CXCL1 (p = 0.0044), IL-7 (p = 0.0035) and IL-8 (p = 0.0176). Elevated CSF levels of PDGF-AA distinguish lymphomas from autoimmune/demyelinating cases (p = 0.0130). Interrogation of the above comparisons using receiver operator characteristic analysis demonstrated area under the curve (AUC) values (ranging from 0.8636–1.0) that signify good to excellent utility as potential diagnostic discriminators. In conclusion, our work indicates that upon formal validation, measurement of CSF cytokine levels may have clinical utility in both identifying a CNS disorder as infectious in etiology and, furthermore, in distinguishing viral from non-viral CNS infections.

Cerebrospinal fluid markers to distinguish bacterial meningitis from cerebral malaria in children

Background. Few hospitals in high malaria endemic countries in Africa have the diagnostic capacity for clinically distinguishing acute bacterial meningitis (ABM) from cerebral malaria (CM). As a result, empirical use of antibiotics is necessary. A biochemical marker of ABM would facilitate precise clinical diagnosis and management of these infections and enable rational use of antibiotics. Methods. We used label-free protein quantification by mass spectrometry to identify cerebrospinal fluid (CSF) markers that distinguish ABM (n=37) from CM (n=22) in Kenyan children. Fold change (FC) and false discovery rates (FDR) were used to identify differentially expressed proteins. Subsequently, potential biomarkers were assessed for their ability to discriminate between ABM and CM using receiver operating characteristic (ROC) curves. Results. The host CSF proteome response to ABM ( Haemophilusinfluenza and Streptococcuspneumoniae) is significantly different to CM. Fifty two proteins were differentially expressed (FDR<0.01, Log FC≥2), of which 83% (43/52) were upregulated in ABM compared to CM. Myeloperoxidase and lactotransferrin were present in 37 (100%) and 36 (97%) of ABM cases, respectively, but absent in CM (n=22). Area under the ROC curve (AUC), sensitivity, and specificity were assessed for myeloperoxidase (1, 1, and 1; 95% CI, 1-1) and lactotransferrin (0.98, 0.97, and 1; 95% CI, 0.96-1). Conclusion. Myeloperoxidase and lactotransferrin have a high potential to distinguish ABM from CM and thereby improve clinical management. Their validation requires a larger cohort of samples that includes other bacterial aetiologies of ABM.

Cerebrospinal fluid markers to distinguish bacterial meningitis from cerebral malaria in children

Background. Few hospitals in high malaria endemic countries in Africa have the diagnostic capacity for clinically distinguishing acute bacterial meningitis (ABM) from cerebral malaria (CM). As a result, empirical use of antibiotics is necessary. A biochemical marker of ABM would facilitate precise clinical diagnosis and management of these infections and enable rational use of antibiotics. Methods. We used label-free protein quantification by mass spectrometry to identify cerebrospinal fluid (CSF) markers that distinguish ABM (n=37) from CM (n=22) in Kenyan children. Fold change (FC) and false discovery rates (FDR) were used to identify differentially expressed proteins. Subsequently, potential biomarkers were assessed for their ability to discriminate between ABM and CM using receiver operating characteristic (ROC) curves. Results. The host CSF proteome response to ABM (Haemophilus influenza and Streptococcus pneumoniae) is significantly different to CM. Fifty two proteins were differentially expressed (FDR<0.01, Log FC≥2), of which 83% (43/52) were upregulated in ABM compared to CM. Myeloperoxidase and lactotransferrin were present in 37 (100%) and 36 (97%) of ABM cases, respectively, but absent in CM (n=22). Area under the ROC curve (AUC), sensitivity, and specificity were assessed for myeloperoxidase (1, 1, and 1; 95% CI, 1-1) and lactotransferrin (0.98, 0.97, and 1; 95% CI, 0.96-1). Conclusion. Myeloperoxidase and lactotransferrin have a high potential to distinguish ABM from CM and thereby improve clinical management. Their validation requires a larger cohort of samples that includes other bacterial aetiologies of ABM.

Acute Encephalitis Syndrome in Adults and Its Correlation with Cytokine Levels in the Serum and Cerebrospinal Fluid

Acute encephalitis syndrome (AES) is a major health problem in developing countries including India. Neuronal injury in encephalitis is attributed to direct toxicity from pathogens and proinflammatory cytokines. In this study, we assessed cytokine levels in serum and cerebrospinal fluid (CSF), and their correlation with clinical symptoms. In our study, patients with AES for a duration of less than 2 weeks underwent brain imaging followed by CSF analysis for routine parameters and viral studies. We assessed interleukin (IL)-6, IL-10, and regulated on activation, normal T cell expressed and secreted (RANTES) levels in the serum samples of all patients and in 50 CSF samples and compared them with serum cytokine levels of 64 age- and sex-matched controls. Of the 87 AES patients, 13 had Japanese encephalitis (JE). Serum IL-6, IL-10, and RANTES levels were significantly elevated in patients with AES compared with that in controls. Serum IL-10 levels were significantly reduced while RANTES levels were significantly elevated in patients who died. CSF IL-6 and IL-10 levels were significantly elevated in the non-JE group compared with that in JE patients. RANTES levels in the CSF were high in patients who had no seizures. IL-10 exerts its anti-inflammatory effect by modulating the innate and adaptive immune response, thus limiting the production of pro-inflammatory cytokines. Higher IL-10 levels were found to be protective in patients with acute encephalitis.

Utility of CSF Cytokine/Chemokines as Markers of Active Intrathecal Inflammation: Comparison of Demyelinating, Anti-NMDAR and Enteroviral Encephalitis

Background

Despite the discovery of CSF and serum diagnostic autoantibodies in autoimmune encephalitis, there are still very limited CSF biomarkers for diagnostic and monitoring purposes in children with inflammatory or autoimmune brain disease. The cause of encephalitis is unknown in up to a third of encephalitis cohorts, and it is important to differentiate infective from autoimmune encephalitis given the therapeutic implications.

Aim

To study CSF cytokines and chemokines as diagnostic biomarkers of active neuroinflammation, and assess their role in differentiating demyelinating, autoimmune, and viral encephalitis.

Methods

We measured and compared 32 cytokine/chemokines using multiplex immunoassay and APRIL and BAFF using ELISA in CSF collected prior to commencing treatment from paediatric patients with confirmed acute disseminated encephalomyelitis (ADEM, n = 16), anti-NMDAR encephalitis (anti-NMDAR E, n = 11), and enteroviral encephalitis (EVE, n = 16). We generated normative data using CSF from 20 non-inflammatory neurological controls. The sensitivity of CSF cytokine/chemokines to diagnose encephalitis cases was calculated using 95^th centile of control values as cut off. We correlated CSF cytokine/chemokines with disease severity and follow up outcome based on modified Rankin scale. One-way hierarchical correlational cluster analysis of molecules was performed in different encephalitis and outcome groups.

Results

In descending order, CSF TNF-α, IL-10, IFN-α, IL-6, CXCL13 and CXCL10 had the best sensitivity (>79.1%) when all encephalitis patients were included. The combination of IL-6 and IFN-α was most predictive of inflammation on multiple logistic regression with area under the ROC curve 0.99 (CI 0.97–1.00). There were no differences in CSF cytokine concentrations between EVE and anti-NMDAR E, whereas ADEM showed more pronounced elevation of Th17 related (IL-17, IL-21) and Th2 (IL-4, CCL17) related cytokine/chemokines. Unlike EVE, heat map analysis showed similar clustering of cytokine/chemokine molecules in immune mediated encephalitis (ADEM and anti-NMDAR E). Th1 and B cell (CXCL13 and CXCL10) molecules clustered together in patients with severe encephalopathy at admission and worse disability at follow up in all encephalitis. There was no correlation between CSF neopterin and IFN-γ or IFN-α.

Conclusion

A combination panel of cytokine/chemokines consisting of CSF TNF-α, IL-10, IFN-α, IL-6, CXCL13 and CXCL10 measured using multiplex immunoassay may be used to diagnose and monitor intrathecal inflammation in the brain. Given their association with worse outcome, certain key chemokines (CXCL13, CXCL10) could represent potential therapeutic targets in encephalitis.