Primary amoebic meningoencephalitis is a rare but fatal central nervous system (CNS) disease caused by the "brain-eating amoeba" Naegleria fowleri. A major obstacle is the requirement for drugs with the ability to cross the blood-brain barrier, which are used in extremely high doses, cause severe side effects, and are usually ineffective. We discovered that the 4-aminomethylphenoxy-benzoxaborole AN3057 exhibits nanomolar potency against N. fowleri, and experimental treatment of infected mice significantly prolonged survival and demonstrated a 28% relapse-free cure rate.
- MeSH
- amébiáza * farmakoterapie MeSH
- hematoencefalická bariéra MeSH
- meningoencefalitida * MeSH
- myši MeSH
- Naegleria fowleri * MeSH
- protozoární infekce centrálního nervového systému * farmakoterapie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: The opportunistic pathogen Naegleria fowleri establishes infection in the human brain, killing almost invariably within 2 weeks. The amoeba performs piece-meal ingestion, or trogocytosis, of brain material causing direct tissue damage and massive inflammation. The cellular basis distinguishing N. fowleri from other Naegleria species, which are all non-pathogenic, is not known. Yet, with the geographic range of N. fowleri advancing, potentially due to climate change, understanding how this pathogen invades and kills is both important and timely. RESULTS: Here, we report an -omics approach to understanding N. fowleri biology and infection at the system level. We sequenced two new strains of N. fowleri and performed a transcriptomic analysis of low- versus high-pathogenicity N. fowleri cultured in a mouse infection model. Comparative analysis provides an in-depth assessment of encoded protein complement between strains, finding high conservation. Molecular evolutionary analyses of multiple diverse cellular systems demonstrate that the N. fowleri genome encodes a similarly complete cellular repertoire to that found in free-living N. gruberi. From transcriptomics, neither stress responses nor traits conferred from lateral gene transfer are suggested as critical for pathogenicity. By contrast, cellular systems such as proteases, lysosomal machinery, and motility, together with metabolic reprogramming and novel N. fowleri proteins, are all implicated in facilitating pathogenicity within the host. Upregulation in mouse-passaged N. fowleri of genes associated with glutamate metabolism and ammonia transport suggests adaptation to available carbon sources in the central nervous system. CONCLUSIONS: In-depth analysis of Naegleria genomes and transcriptomes provides a model of cellular systems involved in opportunistic pathogenicity, uncovering new angles to understanding the biology of a rare but highly fatal pathogen.
- MeSH
- genomika MeSH
- modely nemocí na zvířatech MeSH
- myši MeSH
- Naegleria fowleri * genetika MeSH
- transkriptom MeSH
- trogocytóza MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Copper is a trace metal that is necessary for all organisms but toxic when present in excess. Different mechanisms to avoid copper toxicity have been reported to date in pathogenic organisms such as Cryptococcus neoformans and Candida albicans. However, little if anything is known about pathogenic protozoans despite their importance in human and veterinary medicine. Naegleria fowleri is a free-living amoeba that occurs naturally in warm fresh water and can cause a rapid and deadly brain infection called primary amoebic meningoencephalitis (PAM). Here, we describe the mechanisms employed by N. fowleri to tolerate high copper concentrations, which include various strategies such as copper efflux mediated by a copper-translocating ATPase and upregulation of the expression of antioxidant enzymes and obscure hemerythrin-like and protoglobin-like proteins. The combination of different mechanisms efficiently protects the cell and ensures its high copper tolerance, which can be advantageous both in the natural environment and in the host. Nevertheless, we demonstrate that copper ionophores are potent antiamoebic agents; thus, copper metabolism may be considered a therapeutic target.
- MeSH
- adenosintrifosfatasy metabolismus MeSH
- Amoeba MeSH
- antioxidancia fyziologie MeSH
- lidé MeSH
- měď metabolismus MeSH
- mozek MeSH
- Naegleria fowleri * fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Primary amoebic meningoencephalitis (PAM) is a rapidly fatal infection caused by the free-living amoeba Naegleria fowleri The amoeba migrates along the olfactory nerve to the brain, resulting in seizures, coma, and, eventually, death. Previous research has shown that Naegleria gruberi, a close relative of N. fowleri, prefers lipids over glucose as an energy source. Therefore, we tested several already-approved inhibitors of fatty acid oxidation alongside the currently used drugs amphotericin B and miltefosine. Our data demonstrate that etomoxir, orlistat, perhexiline, thioridazine, and valproic acid inhibited growth of N. gruberi We then tested these compounds on N. fowleri and found etomoxir, perhexiline, and thioridazine to be effective growth inhibitors. Hence, not only are lipids the preferred food source for N. gruberi, but also oxidation of fatty acids seems to be essential for growth of N. fowleri Inhibition of fatty acid oxidation could result in new treatment options, as thioridazine inhibits N. fowleri growth in concentrations that can be reached at the site of infection. It could also potentiate currently used therapy, as checkerboard assays revealed synergy between miltefosine and etomoxir. Animal testing should be performed to confirm the added value of these inhibitors. Although the development of new drugs and randomized controlled trials for this rare disease are nearly impossible, inhibition of fatty acid oxidation seems a promising strategy as we showed effectivity of several drugs that are or have been in use and that thus could be repurposed to treat PAM in the future.
Naegleria fowleri is a single-cell organism living in warm freshwater that can become a deadly human pathogen known as a brain-eating amoeba. The condition caused by N. fowleri, primary amoebic meningoencephalitis, is usually a fatal infection of the brain with rapid and severe onset. Iron is a common element on earth and a crucial cofactor for all living organisms. However, its bioavailable form can be scarce in certain niches, where it becomes a factor that limits growth. To obtain iron, many pathogens use different machineries to exploit an iron-withholding strategy that has evolved in mammals and is important to host-parasite interactions. The present study demonstrates the importance of iron in the biology of N. fowleri and explores the plausibility of exploiting iron as a potential target for therapeutic intervention. We used different biochemical and analytical methods to explore the effect of decreased iron availability on the cellular processes of the amoeba. We show that, under iron starvation, nonessential, iron-dependent, mostly cytosolic pathways in N. fowleri are downregulated, while the metal is utilized in the mitochondria to maintain vital respiratory processes. Surprisingly, N. fowleri fails to respond to acute shortages of iron by inducing the reductive iron uptake system that seems to be the main iron-obtaining strategy of the parasite. Our findings suggest that iron restriction may be used to slow the progression of infection, which may make the difference between life and death for patients.
- Klíčová slova
- primární amébová meningoencefalitida,
- MeSH
- amébiáza * diagnóza epidemiologie mortalita MeSH
- dějiny 20. století MeSH
- dějiny lékařství MeSH
- epidemický výskyt choroby MeSH
- lidé MeSH
- meningoencefalitida etiologie patologie MeSH
- mikrobiologie vody MeSH
- Naegleria fowleri * izolace a purifikace patogenita MeSH
- plavecké bazény MeSH
- protozoární infekce centrálního nervového systému * diagnóza epidemiologie mortalita MeSH
- Check Tag
- dějiny 20. století MeSH
- lidé MeSH
- Publikační typ
- historické články MeSH
- Geografické názvy
- Československo MeSH
Neglerióza alebo primárna amébová meningoencefalitída (PAM) je zriedkavé ochorenie CNS, pôvodcom ktorého je vo¾ne žijúca meòavka Naegleria fowleri. Medzi stovkami vo¾ne žijúcich meòaviek sú známe i ïalšie rody, ktorých zástupcovia sú schopní infikovaś èloveka a vyvolaś u neho ochorenie. Za patogény sú považovaní zástupcovia rodov Acanthamoeba a Naegleria a druhy Balamuthia mandrillaris a Sappinia diploidea. Infekcie spôsobené týmito organizmami vyvolávajú u ¾udí syndrómy v rozsahu od akútnych fatálnych ochorení po chronické, tkanivá napadajúce infekcie s granulomatóznymi prejavmi. Epidemiológia, imunológia, patológia a klinické prejavy týchto infekcií sa vzájomne ve¾mi líšia. Príspevok podáva preh¾ad o pôvodcovi ochorenia PAM, o jeho morfológii, životnom cykle, ekológii ako aj o patogenéze, symptomatike a spôsoboch laboratórnej diagnostiky negleriózy.
Naegleriasis or primary amoebic meningoencephalitis (PAM) is invariably an acute, often fulminant infection of CNS caused by Naegleria fowleri, a small, free-living amoeba. Pathogenic free-living amoebae can cause serious illnesses in humans. The amoebae belonging to the genus Naegleria, Acanthamoeba and Balamuthia mandrillaris and Sappinia diploidea produce syndromes in man ranging from acute fatal disease to chronic tissue invasion with granulomatous manifestation. The purpose of this report is to describe the clinical history, treatment, pathology and methods of laboratory diagnostic of naegleriasis.
