Influenza Virus-associated Encephalopathy Research Articles

Early steroid pulse therapy among children with influenza virus-associated encephalopathy

BackgroundInfluenza virus-associated encephalopathy (IAE) can lead to neurological sequela and mortality among children. Therefore, instant recognition and therapeutic intervention for IAE are crucial. In some clinical subtypes of IAE, steroid pulse therapy might be beneficial, especially when it is administered in the early phase. However, early identification of patients who may benefit from steroid pulse therapy is sometimes difficult. We aimed to assess the effectiveness of early steroid pulse therapy among children with IAE.MethodsIn this retrospective observational study, we used a national database that covers half of the acute care inpatients across Japan to identify inpatients aged ≤ 18 years with a diagnosis of IAE between July 2010 and March 2017. Unfavorable outcome was defined as a composite outcome of sequela including Japan Coma Scale ≥ 10 at discharge, requiring tracheostomy, mechanical ventilation, enteral tube feeding, rehabilitation at discharge, or in-hospital death. Propensity score matching was performed to compare unfavorable outcome and in-hospital mortality between patients with and without steroid pulse therapy within 2 days of admission.ResultsAmong 692 patients included in the study, the mean age was 5.8 years, and 55.8% were male. The overall in-hospital mortality was 1.3%, and the proportion of the unfavorable outcome was 15.0%. We observed no significant difference in the unfavorable outcome between matched patients (168 patients in each group) with and without early steroid pulse therapy (13.7% vs 8.3%; P = 0.16) or in-hospital mortality (0.6% vs 1.2%; P = 1.0).ConclusionsWe did not observe the effectiveness of early steroid pulse therapy on patient outcomes among children with IAE in our study population including all clinical subtypes of IAE. Further studies considering severity of illness are warranted to determine whether steroid pulse therapy is beneficial, especially for specific clinical subtypes of IAE.

Neurotropism of influenza A virus

Influenza A virus is a crucial zoonotic pathogen that is prevalent in diverse avian and mammalian species. With the widespread emergence of novel avian influenza viruses (AIVs), diseases in humans caused by these viruses have increased. Thus, AIVs have become a critical concern to public health. Apart from respiratory symptoms, neurological symptoms can also be caused by AIV infections. The neurotropism of AIV can cause serious illnesses; therefore, it is considered a key criterion in the prognosis of the disease. To summarize the neurotropism of influenza viruses, we review the related findings on neurotropism of human influenza virus and AIV in the following three aspects: the clinical features of influenza virus-associated encephalopathy, the mechanism by which influenza virus invades the central nervous system, and the molecular mechanism of neurotropism.

Elevated serum levels of neutrophil elastase in patients with influenza virus-associated encephalopathy

We examined serum levels of various cytokines, chemokines, growth factors, and adhesion molecules in patients with uncomplicated influenza (n=20) and influenza virus-associated encephalopathy (IE) (n=18) to understand the underlying mechanism of IE. We found that IL-1β, IL-2, IL-5, IL-6, IL-7, IL-8, IL-10, IL-13, G-CSF, GM-CSF, TNF-α, TIMP-1, MMP-9, sE-selectin, and neutrophil elastase were elevated significantly in sera from patients with uncomplicated influenza and those with IE, compared with normal controls (n=20). Of note, neutrophil elastase, sE-selectin, IL-8, and IL-13 were elevated significantly in IE as compared with uncomplicated influenza. In the present study, for the first time, we found that serum levels of neutrophil elastase were increased in patients with IE compared with uncomplicated influenza, which suggested that cerebral endothelial damage in the development of IE was mediated by neutrophil elastase. The present study implied that anti-elastase agents are possibly an effective therapeutic protocol for IE, but this needs further elucidation.

Acute Encephalopathy With Pandemic (H1N1) 2009 Virus Infection

In April 2009, a novel influenza A (H1N1) pdm virus was identified in Mexico and spread quickly around the world. However, the clinical features of acute encephalopathy associated with 2009 pandemic influenza have not yet been elucidated. We treated 8 patients (3 boys and 5 girls) aged 4 to 11 years (average age, 8 y 3 months) with influenza virus-associated encephalopathy, who presented at our 2 hospitals between July 2009 and March 2010. We investigated the clinical characteristics, treatments, and outcomes in the patients. In all patients, brain computed tomography showed mild to severe diffuse cerebral edema, and electroencephalography revealed diffuse high-voltage slow waves. They were all treated with oseltamivir and methylprednisolone pulse therapy. Six patients recovered without any sequelae; however, the remaining 2 had residual neurological sequelae. These 2 patients presented with severe disturbance of consciousness, and their central nervous system symptoms appeared within 12 hours after the onset of fever. One patient had periventricular leukomalacia and symptomatic epilepsy by perinatal brain hypoxia, and the other patient had 1 complex febrile and 2 febrile seizures. This study showed that patients with influenza-associated encephalopathy caused by influenza A (H1N1) pdm infection were all older than those with seasonal influenza. Underlying neurological disease or history may be associated with poor prognosis.

パンデミック（H1N1）2009インフルエンザ脳症の1剖検例

A 16-year-old male was admitted to our hospital because of fever, altered consciousness and subsequent tonic convulsions of upper and lower extremities. A head CT scan revealed evidence of diffuse brain edema. Novel influenza H1N1 viral RNA was detected in nasopharyngeal specimens by specific PCR examination. Oseltamivir, steroid pulse and intravenous immunoglobulin were administered without any effect. On day 3 after admission, the patient died of complications of DIC and multiple organ failure. Autopsy revealed neuropathological changes of the central nervous system, including congestion and marked edema of the brain. However, inflammatory cell infiltration in the meninges or brain parenchyma was not observed. Extensive disruption of astrocytic projections (clasmatodendrosis), which is indicative of acute encephalopathy, was detected by anti-glial fibrillary acidic protein (GFAP) immunostaining of brain tissue. This is the first autopsy case report of pandemic (H1N1) 2009 influenza virus-associated encephalopathy. The clinical course, laboratory profiles and pathological findings were similar to those of conventional seasonal influenza encephalopathy in children that are reported previously.

Serum and cerebrospinal fluid cytokine profile of patients with 2009 pandemic H1N1 influenza virus-associated encephalopathy

PurposeSince April 2009, the number of patients with 2009 pandemic H1N1 influenza virus infection has been increasing in Japan just as in the rest of the world. Patients with 2009 pandemic H1N1 influenza-associated encephalopathy (pIE) have also been reported. The common clinical symptoms of this condition are seizures and progressive coma with high-grade fever. We previously reported the possible association between seasonal influenza-associated encephalopathy (sIE) and proinflammatory cytokines. However, the pathogenesis of pIE remains to be elucidated. ResultsIn pIE patients with a poor outcome, the serum levels of interleukin (IL)-6, IL-10, and soluble tumor necrosis factor (TNF) receptor (sTNFR1) were significantly higher than those in pIE patients without neurological sequelae. Similarly, the cerebrospinal fluid (CSF) IL-6 levels in pIE patients with a poor outcome were significantly higher than those in pIE patients without neurological sequelae. ConclusionOur results suggest that IL-6, TNF-α, and IL-10 play important roles in pIE, and that the serum levels of IL-6, IL-10, and sTNFR1 and the CSF levels of IL-6 are related to neurological complications.

232 Csf Cytokine and Chemokine Profiles in Japanese Patients with West Syndrome

Background and aims: We assessed the cytokine and chemokine profiles of cerebrospinal fluid (CSF) in patients with West syndrome to elucidate whether immunological processes are concerned with the pathophysiology of West syndrome.Methods: We analyzed the CSF levels of Japanese ten patients with West syndrome (WS), eight Influenza virus-associated encephalopathy (IE), as a representative disease with high cytokines storms and twelve controls (cont). All samples of CSF were obtained the first 24 hours after the tonic spasms with informed consent. Seventeen items were measured using the Bio-Plex Multiplex Cytokine Assay, Interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17, G-CSF, GM-CSF, INF-γ, MCP-1, MIP-1β and TNF-α. Statistical differences between three independent groups were tested using the nonparametric Kruskal-Wallis test followed by paired testing using the Mann-Whitney test. A p value of 0.05 was considered significant.Results: All of the CSF of cytokine and chemokine levels in the WS and IE groups was significantly higher than those in the cont group. The CSF levels of IL-6, IL-8, G-CSF, INF-γ and TNF-α in the WS group were significantly lower than those in the IE group. No significant differences of the other cytokines were detected between the WS and IE groups.Conclusions: Our results demonstrate that the increased CSF levels of cytokine and chemokine profiles in patients with West syndrome. A larger study should be conducted to clarify which cytokines are mainly concerned with the pathophysiology of WS.

Lipopolysaccharide treatment and inoculation of influenza A virus results in influenza virus–associated encephalopathy–like changes in neonatal mice

Influenza virus-associated encephalopathy (IAE) is a highly mortal neural complication of influenza A virus (IAV) infection, mostly affecting children younger than 5 years old, and the brain pathology of IAE is characterized by peracute brain edema with evidence of an impaired blood-brain barrier. The pathogenesis of IAE is unknown, but hypercytokinemia of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 is suspected of playing a central role in the development of IAE. Because the brain pathology of IAE is similar to that of septic encephalopathy due to endotoxemia, the effect of combined treatment of IAV and lipopolysaccharide (LPS) was tested using suckling mice. The results show that pulmonary infection with non-neurotropic IAV enhanced the neuropathogenicity of LPS and induced encephalopathy that was similar to IAE with respect to the occurrence of central nervous system (CNS) histopathology and the absence of direct infection of IAV in the brain. Influenza A virus also increased blood-brain barrier (BBB) permeability and induced inflammatory cytokines in the blood. These results suggested that the mice treated with IAV+LPS are possible animal models of IAE, and that hypercytokinemia and/or the involvement of endotoxemia in IAV infection are possible causes of IAE.

Mouse model of influenza virus-associated encephalopathy of childhood

Mouse model of influenza virus-associated encephalopathy of childhood

Diagnostic and predictive value of CSF d-ROM level in influenza virus-associated encephalopathy

The aim of this study was to assess the validity of serum and CSF oxidative status of patients with IE in their initial stage through the d-ROM (Diacron-Reactive Oxygen Metabolites, Italy) test, compared to those with other neurological diseases. The study was conducted on the following four groups: (1) influenza virus-associated encephalopathy (IE, n = 8), including four patients showing neurological sequelae or mortal; (2) influenza virus-associated febrile seizures (IFS, n = 11); (3) febrile convulsion (FC, n = 10): (4) enterovirus-associated encephalopathy (EE, n = 4), including one patient with neurological sequelae. The CSF d-ROM levels in the IE group were significantly higher than those in the IFS and the FC groups but not in the EE group. In addition, general laboratory findings such as leukocytes, platelets, C-reactive protein, aspartate aminotransferase, creatinine, creatinine kinase and LDH, including interleukin-6 (IL-6), were analyzed in each group. The CSF d-ROM levels in the IE group were significantly higher than those in the IFS and FC groups but not in the EE group. As for the serum d-ROM levels and general laboratory findings, with the exception of CSF IL-6 levels in IE, no significant differences were detected compared with the other groups. In patients with IE, the CSF d-ROM levels could be a valid predictive biomarker of the severity, and oxidative stress may be related to the pathogenesis of IE.

Analysis of serum soluble CD40 ligand in patients with influenza virus-associated encephalopathy

CD40 ligand (CD40L) is mainly expressed on activated platelets and CD4 + T cells, and it can be cleaved from the cell surface, releasing a soluble CD40L (sCD40L). Most sCD40L is derived from activated platelets. A previous paper revealed that the platelet number of patients with influenza virus-associated encephalopathy (IE) was correlated with the outcome. We determined the utility of sCD40L as a predictor for the prognosis of IE. We measured the serum concentration of sCD40L and the platelet number on the day of hospitalization in 34 patients with IE, 16 with influenza virus-associated febrile seizures (IFS), 19 with influenza virus infection without complications (Flu), and 7 with Epstein–Barr virus (EBV) infection. The serum sCD40L concentrations in IE and IFS were significantly lower than those in controls, Flu, and EBV infections. Serum sCD40L concentrations in the IE group were 0.70 ± 0.43 ng/ml for deceased patients, 1.73 ± 1.36 ng/ml for those with sequelae, and 3.85 ± 2.91 ng/ml for those without sequelae. There was no significant difference in platelet number between IE patients with and without sequelae, while the platelet number of deceased patients with IE was significantly lower than in controls, Flu, and IFS. Serum sCD40L concentration on the day of hospitalization was more correlated with the outcome of IE than platelet number. Our findings suggest that the serum sCD40L concentration during acute IE is important for predicting the prognosis at an early stage.

Therapeutic outcome of hypothermia therapy in children with influenza virus-associated encephalopathy

In Japan, influenza virus-associated encephalopathy (influenza encephalopathy) has become a topic of public interest, but there is no established reliable treatment. We have already reported that mild hypothermia therapy resulted in excellent recovery for children with acute encephalopathy. We decided to treat influenza encephalopathy using systemic, mild, hypothermia therapy. We investigated the clinical characteristics and therapeutic outcome of this therapy. Subjects were 11 consecutive patients, who were diagnosed with influenza encephalopathy. Systemic mild hypothermia was set at 34–36 °C. Ten children were infected by the Influenza A virus and one by the Influenza B virus. Nine children were medicated with nonsteroidal and antiinflammatory drugs (NSAIDs) prior to onset of encephalopathy. All patients had a blood coagulation abnormality and others. Following hypothermia therapy, 10 children survived, five with handicap and the remaining five without any problem. Considering the severity of encephalopathy in our subjects, mild hypothermia therapy may improve the outcome of children with influenza encephalopathy. Mild hypothermia therapy may be one of the most useful treatments for severe cases of influenza encephalopathy.

Analysis of cytokine levels and NF-κB activation in peripheral blood mononuclear cells in influenza virus-associated encephalopathy

Background Influenza virus-associated encephalopathy (IE) is suggested to be a proinflammatory cytokine-related disease. Methods We measured the concentrations of interleukin-6 (IL-6), TNF-α, soluble TNF receptor 1 (sTNFR1), IL-10, interferon-γ, IL-2, IL-4, and soluble E-selectin (sE-selectin) in serum and CSF during the acute stage in 30 children with IE, 20 with influenza virus-associated febrile seizures (IFS), and 39 with influenza virus infection without complications (Flu). Moreover, the activation of transcription factor NF-κB in peripheral blood mononuclear cells (PBMC) of 5 children with IE was examined. Results The serum IL-6, sTNFR1, and IL-10 levels in the IE group with a poor prognosis (Group A) were significantly higher than those in the IE group without sequelae in IE (Group B), IFS, and Flu. In particular, the serum levels of IL-6, sTNFR1, and IL-10 in 5 deceased patients were markedly higher. The CSF IL-6 levels in Group A were significantly higher than those in Group B and IFS. Flow cytometric analysis revealed that NF-κB activation in PBMC in Group A was higher than that in Group B, IFS, and Flu. Conclusion We suggest that cytokines are produced by PBMC in IE, and that the levels of serum IL-6, sTNFR1, and IL-10, CSF IL-6, and NF-κB activation in PBMC are useful indicators of the severity of the disease.

Predictive value of serum interleukin-6 level in influenza virus-associated encephalopathy.

In Japan, >200 children with influenza virus-associated encephalopathy were reported in 1999 and the mortality rate was high. The levels of tumor necrosis factor-alpha (TNFalpha) and interleukin-6 (IL-6) in both CSF and serum were significantly increased in severe cases. The authors found a correlation between elevated serum cytokine levels and mortality and neurologic morbidity. TNFalpha, IL-6, soluble tumor necrosis factor receptor 1 (sTNF-R1), interferon-gamma (IFNgamma), and IL-2 were measured by the ELISA method in sera from six children with encephalopathy before and during therapy, and in six age-matched controls with influenza type A virus infection. The increases in the serum TNFalpha, IL-6, and sTNF-R1 levels were statistically significant at the onset of symptoms before therapy, but the IL-6 level was most useful for diagnosis. The serum IL-6 levels were >6,000 pg/mL in children with brain stem dysfunction, about 150 pg/mL in children without brain stem dysfunction, and <80 pg/mL in controls. The time course of the serum IL-6 level also reflected the clinical condition. Once the serum IL-6 level was increased to >15,000 pg/mL, none of the children survived. The lower the maximal serum IL-6 level, the milder the CNS sequelae. The serum IL-6 level may be the most useful indicator for the diagnosis and the clinical severity of influenza virus-associated encephalopathy.