Amoebic Meningoencephalitis Research Articles

841Estimation of Undiagnosed Neuroinfectious Deaths with the Epidemiologic Pattern of Primary Amebic Meningoencephalitis Caused by Naegleria fowleri

841Estimation of Undiagnosed Neuroinfectious Deaths with the Epidemiologic Pattern of Primary Amebic Meningoencephalitis Caused by Naegleria fowleri

842First Primary Amebic Meningoencephalitis Death Associated with Exposure to Tap Water from a Treated Public Drinking Water System

842First Primary Amebic Meningoencephalitis Death Associated with Exposure to Tap Water from a Treated Public Drinking Water System

Amebic Meningitis from Nasal Rinsing

Primary amebic meningoencephalitis can ensue when fresh water containing Naegleria fowleri is forcibly introduced into the nose. Such introduction most

Water Recreation and Disease: Plausibility of Associated Infections: Acute Effects, Sequelae and Mortality

Worldwide, the popularity of recreational activities which involve contact with water is continuing to grow. Moreover, ease of travel and change in human behaviour has altered the use of water for recreational purposes. Users should be aware that recreational exposures to pathogens may result in disease. Susceptible populations including people with reduced immune function (e.g., resulting from disease (cancer, HIV), genetic susceptibility, age, etc.) or lack of immunity to locally endemic diseases (e.g., tourists) may be at higher risk of contracting illnesses. In most cases the primary disease symptoms associated with recreational water contact are acute, such as diarrhoea and respiratory infections. Although less frequently reported, more serious and potentially fatal disease is a risk to recreational users of water especially in certain susceptible populations.In addition to diseases which have severe primary outcomes (e.g., primary amoebic meningoencephalitis, typhoid, leptospirosis), a number of infections may lead to sequelae with serious consequences including renal disease (from E. coli O157:H7 for example), cardiac and nutritional disorders. This is the first book to provide a comprehensive review and analysis of potential severe disease outcomes, including acute effects and sequelae, associated with recreational water activities. This book will be useful to all those concerned with recreational water quality, including environmental and public health professionals, local authorities, user groups, and tourists.Water Recreation and Disease sets out to identify the more severe waterborne diseases and their sequelae which may be acquired while undertaking water-based recreation in marine, freshwater, spas/whirlpools and swimming pools. The review systematically brings information together on the ecology and health aspects of a variety of pathogens where cases attributed to recreational use of water have been documented.This is the only available guide to bring together information on the more severe waterborne diseases to assist decision-making in recreational water management.This title belongs to WHO Emerging Issues in Water & Infectious Disease Series..ISBN: 9781780405827 (eBook)ISBN: 9781843390664 (Print)

Expression profile of human neuroblastoma cells after exposure to Naegleria fowleri

Background: Naegleria fowleri, a free-living amoeboflagellate, is the causative agent of life threatening primary amoebic meningoencephalitis with up to a 98% mortality rate. The pathogenesis involves neuronal dysfunction and damages the host central nervous system. Understanding the interactions of the target cells and the protozoa may facilitate an integrated approach to address important biological questions. Objective: We investigated changes in protein expression of the host cells post Naegleria fowleri infection. Methods: The analysis was based on two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) of the proteins extracted from human neuroblastoma SK-N-MC after exposure to N. fowleri trophozoites over a period of six hours. We observed differences in protein expression as early as 15 minutes after the exposure, and the differences remained throughout the six hours study. Results: The identified protein spots corresponded to 53 proteins unique to human and 24 of these proteins were identified as involved in signal transduction, translation, immune response, cytoskeleton, and stress response. We also observed changes in the abundance of these proteins after cocultivating SK-N-MC with N. fowleri, especially those involved in angiogenesis, fatty acid metabolism, signal transduction, translation, stress response, signal pathway, and respiration. Conclusions: The proteomics analysis from this report suggested how and by which means the SK-N-MC responded after N. fowleri infection. Keywords: Host response trophozoites, human neuroblastoma SK-N-MC, Naegleria fowleri infection proteomics

Vaccination with Lentiviral Vector Expressing thenfa1Gene Confers a Protective Immune Response to Mice Infected with Naegleria fowleri

Naegleria fowleri, a pathogenic free-living amoeba, causes fatal primary amoebic meningoencephalitis (PAM) in humans and animals. The nfa1 gene (360 bp), cloned from a cDNA library of N. fowleri, produces a 13.1-kDa recombinant protein which is located on pseudopodia, particularly the food cup structure. The nfa1 gene plays an important role in the pathogenesis of N. fowleri infection. To examine the effect of nfa1 DNA vaccination against N. fowleri infection, we constructed a lentiviral vector (pCDH) expressing the nfa1 gene. For the in vivo mouse study, BALB/c mice were intranasally vaccinated with viral particles of a viral vector expressing the nfa1 gene. To evaluate the effect of vaccination and immune responses of mice, we analyzed the IgG levels (IgG, IgG1, and IgG2a), cytokine induction (interleukin-4 [IL-4] and gamma interferon [IFN-γ]), and survival rates of mice that developed PAM. The levels of both IgG and IgG subclasses (IgG1 and IgG2a) in vaccinated mice were significantly increased. The cytokine analysis showed that vaccinated mice exhibited greater IL-4 and IFN-γ production than the other control groups, suggesting a Th1/Th2 mixed-type immune response. In vaccinated mice, high levels of Nfa1-specific IgG antibodies continued until 12 weeks postvaccination. The mice vaccinated with viral vector expressing the nfa1 gene also exhibited significantly higher survival rates (90%) after challenge with N. fowleri trophozoites. Finally, the nfa1 vaccination effectively induced protective immunity by humoral and cellular immune responses in N. fowleri-infected mice. These results suggest that DNA vaccination using a viral vector may be a potential tool against N. fowleri infection.

Identification and significance of Naegleria fowleri isolated from the hot spring which related to the first primary amebic meningoencephalitis (PAM) patient in Taiwan

Naegleria fowleri can cause primary amoebic meningoencephalitis, a rapidly developing and highly lethal infectious disease. The first confirmed case of primary amoebic meningoencephalitis in Taiwan was reported in November 2011, in which the patient visited a thermal spring recreational area 1week prior to hospitalisation. Water sampling was performed to verify the presence of Naegleria at the facility. According to our results, 32% and 20% of recreational water samples were contaminated with Naegleria spp. and Acanthamoeba spp., respectively. The genotypes of Naegleria identified at the hot spring included N. fowleri, Naegleria australiensis and Naegleria lovaniensis. Using PCR, it was determined that the strain of N. fowleri in one sample possessed the same genotype 2 as the clinical isolate. Thus, the thermal spring was suggested to be the likely source of infection. This is the first known instance of simultaneously isolating N. fowleri from both a patient as well as from a hot spring in Taiwan. Following this initial study, the pools at the thermal spring recreational area were drained, scrubbed and disinfected, and a follow-up study was performed 1month later. Naegleria fowleri was not detected in follow-up testing; however, other Naegleria spp. were identified. We postulate that the biofilm in the waterlines may have provided a reservoir for free-living amoebae. The presence/absence of Acanthamoeba and Naegleria spp. did not differ significantly with any measured parameters related to water quality; however, a high percentage of the thermal water pool samples were contaminated with Naegleria or Acanthamoeba. Thus, amoebic contamination may present a serious threat to the health of humans who engage in leisure activities at thermal springs.

A Fatal Case of Naegleria fowleri Meningoencephalitis in Taiwan

After bathing at a hot spring resort, a 75-year-old man presented to the emergency department because of seizure-like attack with loss of conscious. This is the first case of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri in Taiwan. PAM was diagnosed based on detection of actively motile trophozoites in cerebrospinal fluid using a wet-mount smear and the Liu's stain. The amoebae were further confirmed by PCR and gene sequencing. In spite of administering amphotericin B treatment, the patient died 25 days later.

IL‐1β and IL‐6 activate inflammatory responses of astrocytes against Naegleria fowleri infection via the modulation of MAPKs and AP‐1

Naegleria fowleri, a free-living amoeba, has been found in diverse habitats throughout the world. It causes primary amoebic meningoencephalitis in children and young adults. The amoeba attaches to nasal mucosa, migrates along olfactory nerves and enters the brain. Astrocytes are involved in the defence against infection and produce inflammatory responses. In this study, we focus on the mechanism of immune responses in astrocytes. We showed, using RNase protection assay, RT-PCR and ELISA in an in vitro culture system, that N. fowleri lysates induce interleukin-1beta (IL-1β) and IL-6 expression of astrocytes. In addition, cytokine levels of astrocytes gradually decreased due to extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 inhibitors. To determine the transcription factor, we used transcription inhibitor (AP-1 inhibitor), which downregulated IL-1β and IL-6 expression. These results show that AP-1 is related to IL-1β and IL-6 production. N. fowleri-mediated IL-1β and IL-6 expression requires ERK, JNK and p38 mitogen-activated protein kinases (MAPKs) activation in astrocytes. These findings show that N. fowleri-stimulated astrocytes in an in vitro culture system lead to AP-1 activation and the subsequent expressions of IL-1β and IL-6, which are dependent on ERK, JNK and p38 MAPKs activation. These results may imply that proinflammatory cytokines have important roles in inflammatory responses to N. fowleri infection.

The mitochondrial genome and a 60-kb nuclear DNA segment from Naegleria fowleri, the causative agent of primary amoebic meningoencephalitis.

Naegleria fowleri is a unicellular eukaryote causing primary amoebic meningoencephalitis, a neuropathic disease killing 99% of those infected, usually within 7-14 days. Naegleria fowleri is found globally in regions including the US and Australia. The genome of the related nonpathogenic species Naegleria gruberi has been sequenced, but the genetic basis for N. fowleri pathogenicity is unclear. To generate such insight, we sequenced and assembled the mitochondrial genome and a 60-kb segment of nuclear genome from N. fowleri. The mitochondrial genome is highly similar to its counterpart in N. gruberi in gene complement and organization, while distinct lack of synteny is observed for the nuclear segments. Even in this short (60-kb) segment, we identified examples of potential factors for pathogenesis, including ten novel N. fowleri-specific genes. We also identified a homolog of cathepsin B; proteases proposed to be involved in the pathogenesis of diverse eukaryotic pathogens, including N. fowleri. Finally, we demonstrate a likely case of horizontal gene transfer between N. fowleri and two unrelated amoebae, one of which causes granulomatous amoebic encephalitis. This initial look into the N. fowleri nuclear genome has revealed several examples of potential pathogenesis factors, improving our understanding of a neglected pathogen of increasing global importance.

Differentially expressed genes of Naegleria fowleri during exposure to human neuroblastma cells

Background: Free-living amoeboflagellate, Naegleria fowleri causes acute fulminant primary amoebic meningoencephalitis (PAM). Interaction of N. fowleri with human cells is essential for the cytopathogenic process before phagocytosis and tissue invasion. Objective: In order to understand the pathogenesis mechanisms of N. fowleri, subtractive cDNA library was used to analyze overall induction in gene expression of N. fowleri during exposure to the human neuroblastoma cells. Methods: Co-cultivation of N. fowleri and human neuroblastoma SK-N-MC monolayer cultivation was performed. Subtractive cDNA libraries of inoculated N. fowleri at 15, 30, 45, 60, and 120 minutes were constructed. The PCR amplified products were cloned into E. coli. The specific clones were selected and further sequenced. Nucleotide sequences were compared with those deposited in the Genbank using BlastX. Significant probabilities were considered when E-value was less than 10-4. The induction of several gene expressions was validated by real-time RT-PCR. Results: Extensive changes in gene expression of N. fowleri during the interaction with the human neuroblastoma SK-N-MC in vitro were detected. One hundred twenty clones were obtained. Among these, five clones containing DNA sequence homologue to known genes were identified. These genes included acetyl Co-A synthetase, 18s ribosome RNA, naegleria pore B precursor, isocitrate dehydrogenase, and pyruvate kinase. Real-time quantitative RT-PCR indicated that the expression level of all five genes was up-regulated within 1 hour after exposure. The expression level of acetyl Co-A synthetase increased and reached 7-times significantly greater than that of the control while pyruvate kinase, isocitrate dehydrogenase, naegleria pore B precursor, and 18s ribosome RNA transcripts increased from 2- to 4-fold, respectively. Conclusions: A defined set of genes in N. fowleri that was differentially transcribed after contacting with the SKN- MC monolayer cells was identified. The transcription profiles unique for amoebic cell may help elucidate the transcriptional framework of N. fowleri pathogenicity and serve as a basis for identifying transcriptional virulence factors. Keyword: cDNA subtraction, human neuroblastoma cells, Naegleria fowleri

Survey of Naegleria fowleri in Geothermal Recreational Waters of Guadeloupe (French West Indies)

In 2008 a fatal case of primary amoebic meningoencephalitis, due to the amoeboflagellate Naegleria fowleri, occurred in Guadeloupe, French West Indies, after a child swam in a bath fed with geothermal water. In order to improve the knowledge on free-living amoebae in this tropical part of France, we investigated on a monthly basis, the presence of Naegleria spp. in the recreational baths, and stream waters which feed them. A total of 73 water samples, 48 sediments and 54 swabs samples were collected from 6 sampling points between June 2011 and July 2012. The water samples were filtered and the filters transferred to non-nutrient agar plates seeded with a heat-killed suspension of Escherichia coli while sediment and swab samples were placed directly on these plates. The plates were incubated at 44°C for the selective isolation of thermophilic Naegleria. To identify the Naegleria isolates the internal transcribed spacers, including the 5.8S rDNA, were amplified by polymerase chain reaction and the sequence of the PCR products was determined. Thermophilic amoebae were present at nearly all collection sites. The pathogenic N. fowleri was the most frequently encountered thermophilic species followed by N. lovaniensis. The concentration of N. fowleri was rather low in most water samples, ranging from 0 to 22 per liter. Sequencing revealed that all N. fowleri isolates belonged to a common Euro-American genotype, the same as detected in the human case in Guadeloupe. These investigations need to be continued in order to counsel the health authorities about prevention measures, because these recreational thermal baths are used daily by local people and tourists.

Improved Method for the Detection and Quantification ofNaegleria fowleriin Water and Sediment Using Immunomagnetic Separation and Real-Time PCR

Primary amebic meningoencephalitis (PAM) is a rare and typically fatal infection caused by the thermophilic free-living ameba, Naegleria fowleri. In 2010, the first confirmed case of PAM acquired in Minnesota highlighted the need for improved detection and quantification methods in order to study the changing ecology of N. fowleri and to evaluate potential risk factors for increased exposure. An immunomagnetic separation (IMS) procedure and real-time PCR TaqMan assay were developed to recover and quantify N. fowleri in water and sediment samples. When one liter of lake water was seeded with N. fowleri strain CDC:V212, the method had an average recovery of 46% and detection limit of 14 amebas per liter of water. The method was then applied to sediment and water samples with unknown N. fowleri concentrations, resulting in positive direct detections by real-time PCR in 3 out of 16 samples and confirmation of N. fowleri culture in 6 of 16 samples. This study has resulted in a new method for detection and quantification of N. fowleri in water and sediment that should be a useful tool to facilitate studies of the physical, chemical, and biological factors associated with the presence and dynamics of N. fowleri in environmental systems.

Fatal consequences of freshwater pearl diving

In July, 2012, a 25-year-old man was admitted to our hospital with headache, fever, and reduced consciousness. He had an unremarkable medical history and took no regular medications. He worked as a peanut vendor and before becoming unwell had visited relatives in the countryside. During this time he had attended a wedding and dived for pearls in a freshwater lake. 1 week after returning to the city he developed headache and fever, for which he took paracetamol. The next day his headache worsened in severity and he presented to his local hospital, where staff noted that he was confused. He was given a dose of ceftriaxone to cover bacterial meningitis and was transferred to our hospital. On initial assessment, he had a temperature of 39°C. His Glasgow coma scale score was 10 (M=5, V=2, E=3). His neck was stiff . He had no rash and was haemodynamically stable. Initial blood tests showed raised white cell count of 13·34×109 per L with 89% neutrophils. Lumbar puncture was done, which showed an opening pressure of 38 cm H2O. Cerebrospinal fl uid (CSF) contained 3260 × 103 per mL white cells with 88% neutrophils. CSF protein was 7·9 g/L, and glucose was 0·15 mmol/L. Plasma glucose was 8·62 mmol/L. Gram and Zeil-Neilsen stains were negative. However, on wet mount microscopy numerous amoebae were seen (see fi gure and webvideo). He had already started ceftriaxone and dexamethasone for presumed bacterial meningitis. In view of the CSF fi ndings and history of exposure to freshwater a diagnosis of primary amoebic meningoencephalitis was considered. Amphotericin B and rifampicin were started. Later on the day of admission his condition deteriorated and he required intubation and ventilation. He subsequently went into cardiac arrest and could not be resuscitated. Polymerase chain reaction Lancet 2013; 381: 176

Disruption of MDCK cell tight junctions by the free-living amoeba Naegleria fowleri

Naegleria fowleri is the aetiological agent of primary amoebic meningoencephalitis. This parasite invades its host by penetrating the olfactory mucosa. However, the mechanism of epithelium penetration is not well understood. In the present study, we evaluated the effect of N. fowleri trophozoites and the non-pathogenic Naegleria gruberi on Madin-Darby canine kidney (MDCK) tight junction proteins, including claudin-1, occludin and ZO-1, as well as on the actin cytoskeleton. Trophozoites from each of the free-living amoeba species were co-cultured with MDCK cells in a 1 : 1 ratio for 1, 3, 6 or 10 h. Light microscopy revealed that N. fowleri caused morphological changes as early as 3 h post-infection in an epithelial MDCK monolayer. Confocal microscopy analysis revealed that after 10 h of co-culture, N. fowleri trophozoites induced epithelial cell damage, which was characterized by changes in the actin apical ring and disruption of the ZO-1 and claudin-1 proteins but not occludin. Western blot assays revealed gradual degradation of ZO-1 and claudin-1 as early as 3 h post-infection. Likewise, there was a drop in transepithelial electrical resistance that resulted in increased epithelial permeability and facilitated the invasion of N. fowleri trophozoites by a paracellular route. In contrast, N. gruberi did not induce alterations in MDCK cells even at 10 h post-infection. Based on these results, we suggest that N. fowleri trophozoites disrupt epithelial monolayers, which could enable their penetration of the olfactory epithelium and subsequent invasion of the central nervous system.

The immune response induced by DNA vaccine expressing nfa1 gene against Naegleria fowleri

The pathogenic free-living amoeba, Naegleria fowleri, causes fatal primary amoebic meningoencephalitis in experimental animals and in humans. The nfa1 gene that was cloned from N. fowleri is located on pseudopodia, especially amoebic food cups and plays an important role in the pathogenesis of N. fowleri. In this study, we constructed and characterized retroviral vector and lentiviral vector systems for nfa1 DNA vaccination in mice. We constructed the retroviral vector (pQCXIN) and the lentiviral vector (pCDH) cloned with the egfp-nfa1 gene. The expression of nfa1 gene in Chinese hamster ovary cell and human primary nasal epithelial cell transfected with the pQCXIN/egfp-nfa1 vector or pCDH/egfp-nfa1 vector was observed by fluorescent microscopy and Western blotting analysis. Our viral vector systems effectively delivered the nfa1 gene to the target cells and expressed the Nfa1 protein within the target cells. To evaluate immune responses of nfa1-vaccinated mice, BALB/c mice were intranasally vaccinated with viral particles of each retro- or lentiviral vector expressing nfa1 gene. DNA vaccination using viral vectors expressing nfa1 significantly stimulated the production of Nfa1-specific IgG subclass, as well as IgG levels. In particular, both levels of IgG2a (Th1) and IgG1 (Th2) were significantly increased in mice vaccinated with viral vectors. These results show the nfa1-vaccination induce efficiently Th1 type, as well as Th2 type immune responses. This is the first report to construct viral vector systems and to evaluate immune responses as DNA vaccination in N. fowleri infection. Furthermore, these results suggest that nfal vaccination may be an effective method for treatment of N. fowleri infection.

Primary Amebic Meningoencephalitis Deaths Associated With Sinus Irrigation Using Contaminated Tap Water

Naegleria fowleri is a climate-sensitive, thermophilic ameba found in the environment, including warm, freshwater lakes and rivers. Primary amebic meningoencephalitis (PAM), which is almost universally fatal, occurs when N. fowleri-containing water enters the nose, typically during swimming, and N. fowleri migrates to the brain via the olfactory nerve. In 2011, 2 adults died in Louisiana hospitals of infectious meningoencephalitis after brief illnesses. Clinical and environmental testing and case investigations were initiated to determine the cause of death and to identify the exposures. Both patients had diagnoses of PAM. Their only reported water exposures were tap water used for household activities, including regular sinus irrigation with neti pots. Water samples, tap swab samples, and neti pots were collected from both households and tested; N. fowleri were identified in water samples from both homes. These are the first reported PAM cases in the United States associated with the presence of N. fowleri in household plumbing served by treated municipal water supplies and the first reports of PAM potentially associated with the use of a nasal irrigation device. These cases occurred in the context of an expanding geographic range for PAM beyond southern tier states with recent case reports from Minnesota, Kansas, and Virginia. These infections introduce an additional consideration for physicians recommending nasal irrigation and demonstrate the importance of using appropriate water (distilled, boiled, filtered) for nasal irrigation. Furthermore, the changing epidemiology of PAM highlights the importance of raising awareness about this disease among physicians treating persons showing meningitislike symptoms.

Development of a high- versus low-pathogenicity model of the free-living amoeba Naegleria fowleri

Species in the genus Naegleria are free-living amoebae of the soil and warm fresh water. Although around 30 species have been recognized, Naegleria fowleri is the only one that causes primary amoebic meningoencephalitis (PAM) in humans. PAM is an acute and fast progressing disease affecting the central nervous system. Most of the patients die within 1-2 weeks of exposure to the infectious water source. The fact that N. fowleri causes such fast progressing and highly lethal infections has opened many questions regarding the relevant pathogenicity factors of the amoeba. In order to investigate the pathogenesis of N. fowleri under defined experimental conditions, we developed a novel high- versus low-pathogenicity model for this pathogen. We showed that the composition of the axenic growth media influenced growth behaviour and morphology, as well as in vitro cytotoxicity and in vivo pathogenicity of N. fowleri. Trophozoites maintained in Nelson's medium were highly pathogenic for mice, demonstrated rapid in vitro proliferation, characteristic expression of surface membrane vesicles and a small cell diameter, and killed target mouse fibroblasts by both contact-dependent and -independent destruction. In contrast, N. fowleri cultured in PYNFH medium exhibited a low pathogenicity, slower growth, increased cell size and contact-dependent target cell destruction. However, cultivation of the amoeba in PYNFH medium supplemented with liver hydrolysate (LH) resulted in trophozoites that were highly pathogenic in mice, and demonstrated an intermediate proliferation rate in vitro, diminished cell diameter and contact-dependent target cell destruction. Thus, in this model, the presence of LH resulted in increased proliferation of trophozoites in vitro and enhanced pathogenicity of N. fowleri in mice. However, neither in vitro cytotoxicity mechanisms nor the presence of membrane vesicles on the surface correlated with the pathologic potential of the amoeba. This indicated that the pathogenicity of N. fowleri remains a complex interaction between as-yet-unidentified cellular mechanisms.

Youngest Survivor of Naegleria Meningitis

Primary amebic meningoencephalitis (PAME) is a rare condition, usually caused by free living motile amebae. These are universally fatal infections with very few survivors reported till now. The authors report a 25-d-old boy, the youngest survivor of Naegleria meningitis. The child was admitted with a diagnosis of partially treated meningitis. Cerebro-spinal fluid wet mount examination revealed free living motile amebae resembling Naegleria, which was further confirmed by culture. He was treated with amphoterecin B, rifampicin and fluconazole for 4 wk and ventriculoperitoneal shunt for obstructive hydrocephalous. At 8 mo follow up, child has survived with neurological sequlae.

Induction of interleukin-8 by Naegleria fowleri lysates requires activation of extracellular signal-regulated kinase in human astroglial cells

Naegleria fowleri is a pathogenic free-living amoeba which causes primary amoebic meningoencephalitis in humans and experimental animals. To investigate the mechanisms of such inflammatory diseases, potential chemokine gene activation in human astroglial cells was investigated following treatment with N. fowleri lysates. We demonstrated that N. fowleri are potent inducers for the expression of interleukin-8 (IL-8) genes in human astroglial cells which was preceded by activation of extracellular signal-regulated kinase (ERK). In addition, N. fowleri lysates induces the DNA binding activity of activator protein-1 (AP-1), an important transcription factor for IL-8 induction. The specific mitogen-activated protein kinase kinase/ERK inhibitor, U0126, blocks N. fowleri-mediated AP-1 activation and subsequent IL-8 induction. N. fowleri-induced IL-8 expression requires activation of ERK in human astroglial cells. These findings indicate that treatment of N. fowleri on human astroglial cells leads to the activation of AP-1 and subsequent expression of IL-8 which are dependent on ERK activation. These results may help understand the N. fowleri-mediated upregulation of chemokine and cytokine expression in the astroglial cells.